Liquid ejection device and control method thereof

Abstract

To provide a liquid discharge device which can execute inspection of a nozzle in a short time, and a liquid discharge device control method.SOLUTION: A liquid discharge device comprises a first actuator and a second actuator corresponding to a first nozzle and a second nozzle, and a controller. Each of the first actuator and the second actuator has a piezoelectric material which is deformed for discharging liquid from the nozzle, and at least two electrodes which hold the piezoelectric material therebetween. The controller detects a synthetic capacity of the piezoelectric materials of the first actuator and the second actuator, and determines whether a value based on the detected synthetic capacity is an abnormal value or not. When the control determines that the value based on the synthetic capacity is an abnormal value, the controller detects vibration waveforms generated by vibration of the piezoelectric materials after driving the first actuator and the second actuator for the first actuator and the second actuator respectively, and determines whether the detected vibration waveforms are abnormal waveforms.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present technology relates to a liquid ejection device that ejects liquid from nozzles and a control method for the liquid ejection device.

Background Art

[0002] There is a liquid ejection device including a plurality of nozzles that eject liquid and piezoelectric actuators corresponding to the respective nozzles. The piezoelectric actuator includes a pressure chamber, a diaphragm, and an electrode. By applying a voltage to the electrode, the diaphragm vibrates, and liquid is ejected from the nozzle.

[0003] After applying a voltage to the electrode, the diaphragm undergoes residual vibration (free vibration). Based on the waveform due to the residual vibration, that is, the residual wave, it is possible to inspect the state of the nozzle, for example, the presence or absence of liquid clogging or the mixing of air bubbles into the liquid (see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The inspection of the nozzle based on the residual wave requires two steps, namely, applying a voltage to the electrode and measuring the residual wave, and these two steps are executed for each nozzle. Therefore, it takes a long time to inspect the nozzles.

[0006] The present disclosure has been made in view of such circumstances, and an object thereof is to provide a liquid ejection device and a control method for the liquid ejection device that can execute the inspection of the nozzle in a short time.

Means for Solving the Problems

[0007] A liquid ejection device according to an embodiment of the present disclosure includes a first nozzle group having a plurality of nozzles including a first nozzle and a second nozzle, a first actuator and a second actuator corresponding to the first nozzle and the second nozzle, and a controller. Each of the first actuator and the second actuator has a piezoelectric body deformed to eject liquid from the nozzle and at least two electrodes sandwiching the piezoelectric body. The controller performs a first detection process of detecting a combined capacitance of the piezoelectric bodies of the first actuator and the second actuator, a first determination process of determining whether a value based on the combined capacitance detected in the first detection process is an abnormal value, a driving process of driving the first actuator and the second actuator when it is determined that the value based on the combined capacitance is an abnormal value, a second detection process of detecting a vibration waveform generated by vibration of the piezoelectric body after driving the first actuator and the second actuator for each of the piezoelectric bodies of the first actuator and the second actuator, and a second determination process of determining whether the vibration waveform detected in the second detection process is an abnormal waveform.

[0008] A control method for a liquid ejection device according to an embodiment of the present disclosure includes a first nozzle group having a plurality of nozzles including a first nozzle and a second nozzle, a first actuator and a second actuator corresponding to the first nozzle and the second nozzle, and a controller. Each of the first actuator and the second actuator has a piezoelectric body deformed to eject liquid from the nozzle and at least two electrodes sandwiching the piezoelectric body. The control method for the liquid ejection device is characterized in that the controller performs a first detection process of detecting the combined capacitance of the piezoelectric bodies of the first actuator and the second actuator, a first determination process of determining whether a value based on the combined capacitance detected in the first detection process is an abnormal value, a driving process of driving the first actuator and the second actuator when it is determined that the value based on the combined capacitance is an abnormal value, a second detection process of detecting, for each of the piezoelectric bodies of the first actuator and the second actuator, a vibration waveform generated by vibration of the piezoelectric body after driving the first actuator and the second actuator, and a second determination process of determining whether the vibration waveform detected in the second detection process is an abnormal waveform.

Advantages of the Invention

[0009] In the liquid ejection device and the control method for the liquid ejection device according to an embodiment of the present disclosure, it is determined whether there is an abnormality in the nozzle group based on a value based on the combined capacitance, and only when it is determined that there is an abnormality, an inspection based on the vibration waveform is performed on each nozzle included in the nozzle group, so that the time required for the inspection can be reduced.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Embodiments for Carrying Out the Invention

[0011] (Embodiment 1) Hereinafter, the present invention will be described based on the drawings showing a printing apparatus according to Embodiment 1. FIG. 1 is a plan view schematically showing the printing apparatus, and FIG. 2 is an explanatory diagram for explaining the flow of ink between a sub-tank and an inkjet head. In the following description, the front, rear, left, and right shown in FIG. 1 are used. The front-rear direction corresponds to the conveyance direction, and the left-right direction corresponds to the scanning direction. Also, the front side of FIG. 1 corresponds to the upper side, the back side corresponds to the lower side, and the up-down is also used. The printing apparatus corresponds to a liquid ejection apparatus.

[0012] As shown in FIG. 1, the printing apparatus 1 includes a platen 2, an ink ejection device 3, conveyance rollers 4, 5, etc. On the upper surface of the platen 2, a recording sheet 200, which is a recording medium, is placed. The ink ejection device 3 ejects ink onto the recording sheet 200 placed on the platen 2 to record an image. The ink ejection device 3 includes a carriage 6, a sub-tank 7, four inkjet heads 8, a circulation pump 10 (see FIG. 2), etc.

[0013] On the upper side of the platen 2, two guide rails 11, 12 extending left and right for guiding the carriage 6 are provided. An endless belt 13 extending left and right is connected to the carriage 6. The endless belt 13 is driven by a carriage drive motor 14. By driving the endless belt 13, the carriage 6 is guided by the guide rails 11, 12 and reciprocates in the scanning direction in the region facing the platen 2.

[0014] Between the guide rails 11, 12, a cap 20 and a flushing receiver 21 are provided. The cap 20 and the flushing receiver 21 are arranged below the ink ejection device 3. The cap 20 is arranged at the right end of the guide rails 11, 12, and the flushing receiver 21 is arranged at the left end of the guide rails 11, 12. That is, the carriage 6 moves the inkjet head 8 between the cap 20 and the flushing receiver 21. Note that the cap 20 and the flushing receiver 21 may be arranged in reverse left and right, or both may be arranged on either the left or the right.

[0015] The sub-tank 7 and the four inkjet heads 8 are mounted on the carriage 6 and reciprocate in the scanning direction together with the carriage 6. The sub-tank 7 is connected via a cartridge holder 15 and a tube 17. One or more ink cartridges 16 of a plurality of colors (in this embodiment, 4 colors) are mounted on the cartridge holder 15. Examples of the 4 colors include black, yellow, cyan, and magenta.

[0016] As shown in FIG. 2, four ink chambers 19 are formed inside the sub-tank 7. The four ink chambers 19 store the four-color inks supplied from the four ink cartridges 16 respectively.

[0017] The four inkjet heads 8 are arranged side by side in the scanning direction below the sub-tank 7. A plurality of nozzles 80 (see FIG. 3) are formed on the lower surface of each inkjet head 8. As shown in FIG. 2, one inkjet head 8 corresponds to one color of ink and is connected to one ink chamber 19. That is, the four inkjet heads 8 respectively correspond to the four-color inks and are respectively connected to the four ink chambers 19.

[0018] As shown in FIG. 2, an ink supply port 8a and an ink discharge port 8b are provided on the upper surface of the inkjet head 8. The ink supply port 8a and the ink discharge port 8b are connected to the ink chamber 19 via a tube or the like. A circulation pump 10 is interposed between the ink supply port 8a and the ink chamber 19.

[0019] The circulation pump 10 is a tube pump that extrudes the liquid in the tube, for example, by squeezing the tube with a rotor. The circulation pump 10 sends the ink in the ink chamber 19 into the inkjet head 8.

[0020] The ink sent out from the ink chamber 19 by the circulation pump 10 flows into the inkjet head 8 through the ink supply port 8a and is ejected from the nozzles 80. The ink that is not ejected from the nozzles 80 returns to the ink chamber 19 through the ink discharge port 8b. The ink circulates between the ink chamber 19 and the inkjet head 8. Instead of the circulation pump 10, other power sources for circulation, for example, a device that sends compressed air into the sub-tank 7 to send the ink into the inkjet head 8, may be used. The four inkjet heads 8 eject the four-color inks supplied from the sub-tank 7 onto the recording paper 200 while moving in the scanning direction together with the carriage.

[0021] As shown in FIG. 1, the conveyance roller 4 is disposed on the upstream side (rear side) in the conveyance direction with respect to the platen 2. The conveyance roller 5 is disposed on the downstream side (front side) in the conveyance direction with respect to the platen 2. The two conveyance rollers 4 and 5 are driven synchronously by a motor (not shown). The two conveyance rollers 4 and 5 convey the recording paper 200 placed on the platen 2 in the conveyance direction orthogonal to the scanning direction. The printing apparatus 1 includes a control device 50. The control device 50 includes a CPU or a logic circuit (e.g., FPGA), a storage unit 50a such as a non-volatile memory and a RAM. The control device 50 receives a print job from an external device 100 and stores it in the storage unit 50a. Further, the storage unit 50a stores a table and threshold values to be described later. The control device 50 controls the driving of the ink ejection device 3, the conveyance roller 4, etc. based on the print job, and executes printing processing.

[0022] FIG. 3 is a schematic partial enlarged cross-sectional view of the inkjet head 8. The inkjet head 8 includes a plurality of pressure chambers 81. The plurality of pressure chambers 81 constitute a plurality of pressure chamber rows. A diaphragm 82 is formed above the pressure chamber 81. A layered piezoelectric body 83 is formed above the diaphragm 82. A common electrode 84 is formed between the piezoelectric body 83 and the diaphragm 82 above each pressure chamber 81. An individual electrode 85 is formed on the upper surface of the piezoelectric body 83 above each pressure chamber 81. The individual electrode 85 and the common electrode 84 face each other vertically with the piezoelectric body 83 interposed therebetween. A nozzle plate 87 is provided below each pressure chamber 81. A plurality of nozzles 80 penetrating vertically are formed in the nozzle plate 87. Each nozzle 80 is disposed below each pressure chamber 81. The plurality of nozzles 80 constitute a plurality of nozzle rows including a first nozzle row 80a and a second nozzle row 80b (see FIG. 6). The nozzle rows extend along the pressure chamber rows. The common electrode 84 is disposed across the first nozzle row 80a and the second nozzle row 80b.

[0023] The common electrode 84 is connected to the COM terminal, which is grounded in this embodiment. The individual electrode 85 is connected to the switch control unit 67. A High or Low voltage is applied to the individual electrode 85, causing the piezoelectric body 83 to deform and the diaphragm 82 to vibrate. Due to the vibration of the diaphragm 82, ink is ejected from the pressure chamber 81 through the nozzle 80. The pressure chamber 81, diaphragm 82, piezoelectric body 83, common electrode 84, and individual electrode 85 constitute the actuator 88.

[0024] FIG. 4 is a block diagram schematically showing the configuration of the controller 51 and the like. The printing apparatus 1 includes a controller 51, a D / A converter 52, a discharge amplifier 53, an A / D converter 54, a vibration waveform amplifier 55, a capacitance detection circuit 56, and a switching driver 57. The switching driver 57 includes a plurality of switch groups 57(1), 57(2), ···, 57(n). The plurality of nozzles 80 respectively correspond to the plurality of actuators 88. Hereinafter, the plurality of actuators 88 will also be described as actuators 88(1), 88(2), ···, 88(n).

[0025] The plurality of switch groups 57(1), 57(2), ···, 57(n) respectively correspond to the plurality of nozzles 80 (there are n nozzles) and also respectively correspond to the plurality of actuators 88(1), 88(2), ···, 88(n). Each switch group 57(1), 57(2), ···, 57(n) includes a first switch 571, a second switch 572, and a third switch 573. For example, the third switch 573 of the switch group 57(1) corresponds to the first switching element, and the third switch 573 of the switch group 57(2) corresponds to the second switching element. The second switch 572 of the switch group 57(1) corresponds to the third switching element, and the second switch 572 of the switch group 57(2) corresponds to the fourth switching element.

[0026] One end of the first switch 571 of each switch group 57(1), 57(2), ···, 57(n) is connected to the discharge amplifier 53. One end of the second switch 572 of each switch group 57(1), 57(2), ···, 57(n) is connected to the vibration waveform amplifier 55. One end of the third switch 573 of each switch group 57(1), 57(2), ···, 57(n) is connected to the capacitance detection circuit 56.

[0027] The other ends of the first switches 571 of the switch groups 57(1), 57(2), ···, 57(n) are respectively connected to the individual electrodes 85 of the actuators 88(1), 88(2), ···, 88(n). The other ends of the second switches 572 of the switch groups 57(1), 57(2), ···, 57(n) are respectively connected to the individual electrodes 85 of the actuators 88(1), 88(2), ···, 88(n). The other ends of the third switches 573 of the switch groups 57(1), 57(2), ···, 57(n) are respectively connected to the individual electrodes 85 of the actuators 88(1), 88(2), ···, 88(n).

[0028] The case of detecting the combined capacitance of the piezoelectric bodies 83 of each of the actuators 88(1) to (n) will be described. After applying a voltage to the individual electrodes 85 of each of the actuators 88(1) to (n), the controller 51 outputs an open / close signal to the switching driver 57. The controller 51 opens the first switches 571 and the second switches of each of the switch groups 57(1) to 57(n), and closes the third switches 573 of each of the switch groups 57(1) to 57(n). The charges accumulated in each piezoelectric body 83 are input to the capacitance detection circuit 56 through the third switch 573, and the capacitance detection circuit 56 detects the combined capacitance of each piezoelectric body 83 based on the input charges and outputs it to the controller 51.

[0029] When inspecting the state of the nozzle 80 based on the vibration waveform of the actuator 88, the controller 51 performs the following control. For example, it is assumed that the actuator 88(1) corresponds to the nozzle 80 to be inspected. The controller 51 closes the first switch 571 of the actuator 88(1). The controller 51 closes the second switch 572 and the third switch 573 of the actuator 88(1) to apply a voltage to the individual electrode 85 of the actuator 88(1).

[0030] After that, the controller 51 closes the second switch 572 of the actuator 88(1), and closes the first switch 571 and the third switch 573 of the actuator 88(1). The vibration waveform generated by the vibration of the piezoelectric body 83 of the actuator 88(1) is input to the vibration waveform amplifier 55. The vibration waveform input to the vibration waveform amplifier 55 is amplified and input to the A / D converter 54. The vibration waveform is an analog signal.

[0031] The A / D converter 54 converts the input vibration waveform into a digital signal and outputs it to the controller 51. The controller 51 inspects the state of the nozzle 80 based on the input vibration waveform. When inspecting the state of the nozzle 80 corresponding to the actuator 88(1), the first switches 571 to the third switches 573 of the other actuators 88(2) to 88(n) are open. The controller 51 executes the same control when inspecting the states of the nozzles 80 corresponding to the actuators 88(2) to 88(n). The capacitance detection circuit 56 corresponds to the first detection circuit, and the controller 51, the A / D converter 54, and the vibration waveform amplifier 55 correspond to the second detection circuit.

[0032] FIG. 5 is a conceptual diagram showing an example of a table stored in the storage unit 50a, and FIG. 6 is an explanatory diagram for explaining the relationship between nozzle addresses and group identifiers. The arrow in FIG. 6 schematically shows the flow of ink from the ink supply port 8a to the ink discharge port 8b in the inkjet head 8. That is, the side where the ink supply port 8a is located is the upstream, and the side where the ink discharge port 8b is located is the downstream. As shown in FIG. 6, the inkjet head 8 includes a first nozzle row 80a and a second nozzle row 80b. The first nozzle row 80a is arranged on the left side, and the second nozzle row 80b is arranged on the right side.

[0033] Nozzle addresses N(1), N(2), ···, N(p) are assigned to each of the plurality of nozzles 80 that constitute the first nozzle row 80a. In the present embodiment, the nozzle addresses N(1), N(2), ···, N(p) are assigned in order from upstream to downstream.

[0034] Nozzle addresses M(1), M(2), ···, M(p) are assigned to each of the plurality of nozzles 80 that constitute the second nozzle row 80b. In the present embodiment, the nozzle addresses M(1), M(2), ···, M(p) are assigned in order from upstream to downstream. Note that 2p = n.

[0035] As shown in FIG. 6, for example, the group identifier G(1) corresponds to the nozzle addresses N(1) and N(2), the group identifier G(2) corresponds to the nozzle addresses N(3) and the nozzle address N(4), the group identifier G(k - 1) corresponds to the nozzle addresses N(p - 3) and N(p - 2), and the group identifier G(k) corresponds to the nozzle addresses N(p - 1) and N(p). The nozzles 80 to which the same group identifier G(k) is assigned belong to the same group (k). The nozzle addresses N(1) to N(p) correspond to, for example, actuators 88(1) to 88(p).

[0036] Also, the group identifier G(1) corresponds to the nozzle addresses M(1) and M(2), the group identifier G(2) corresponds to the nozzle addresses M(3) and M(4), the group identifier G(k - 1) corresponds to the nozzle addresses M(p - 3) and M(p - 2), and the group identifier G(k) corresponds to the nozzle addresses M(p - 1) and M(p). The nozzle addresses M(1) to M(p) correspond to, for example, the actuators 88(p + 1) to 88(n).

[0037] The nozzle 80 with the nozzle address N(1) corresponds to the most upstream nozzle, the nozzle with the nozzle address N(2) corresponds to the first adjacent nozzle, the nozzle 80 with the nozzle address N(3) corresponds to the third adjacent nozzle, and the nozzle 80 with the nozzle address N(4) corresponds to the fourth adjacent nozzle.

[0038] Figure 7 is a flowchart for explaining the printing process by the control device 50. The control device 50 determines whether it has received a print job from the external device 100 (S1). If it has not received a print job (S1: NO), the control device 50 returns the process to step S1. If it has received a print job (S1: YES), the control device 50 executes a flushing process (S2). The flushing process is a process of discharging ink from the nozzles 80 for purposes other than printing.

[0039] Next, the control device 50 causes the controller 51 to execute a non - discharge detection process (S3). Details of the non - discharge detection process will be described later. Next, the control device 50 executes one print task (S4). A print task is a unit that constitutes a print job. Specifically, the print task is a liquid discharge process performed while the inkjet head 8 moves the left - right width of the recording paper 200 to the right or left. Next, the control device 50 determines whether one print task has been completed (S5). If one print task has not been completed (S5: NO), the process returns to step S5. If one print task has been completed (S5: YES), the control device 50 determines whether the print job has been completed (S6).

[0040] When the printing job is completed (S6: YES), the control device 50 ends the printing process. When the printing job is not completed (S6: NO), the control device 50 determines whether the two-print task has been completed (S7). Note that the two-print task is an example, and it may be determined whether one-print task or three-print task has been completed. When the two-print task is completed (S7: YES), the control device 50 determines whether it is the timing to perform the flushing process (S8). The flushing process is periodically executed for the maintenance of the nozzles 80. When it is the timing to perform the flushing process (S8: YES), the control device 50 executes the flushing process (S9). The control device 50 executes the non-discharge detection process (S10) and returns the process to step S4.

[0041] In step S8, when it is not the timing to perform the flushing process (S8: NO), the control device 50 executes the non-discharge detection process (S15) and returns the process to step S4.

[0042] In step S7, when the two-print task is not completed (S7: NO), the control device 50 determines whether it is the timing to perform the flushing process (S11). When it is the timing to perform the flushing process (S11: YES), the control device 50 executes the flushing process (S12) and returns the process to step S4.

[0043] In step S11, when it is not the timing to perform the flushing process (S11: NO), the control device 50 determines whether it is the timing to execute the non-discharge flushing process. The non-discharge flushing process is a process for preventing the nozzles 80 from drying without discharging the liquid. Specifically, it is a process of slightly deforming the piezoelectric body 83 to shake the liquid surface (meniscus). The non-discharge flushing process is periodically executed. When it is the timing to execute the non-discharge flushing process (S13: YES), the control device 50 executes the non-discharge flushing process (S14) and returns the process to step S4. When it is not the timing to execute the non-discharge flushing process (S13: NO), the control device 50 returns the process to step S4.

[0044] Figure 8 is a flowchart for explaining the non-discharge detection process by the controller 51. In the above steps S3, S10, and S15, the control device 50 causes the controller 51 to execute the non-discharge detection process. The non-discharge detection process is executed by software installed in the controller 51. The controller 51 designates a group identifier for detecting capacitance (S21), closes the third switches 573 of all the nozzles 80 corresponding to the designated group identifier (S22), and detects the combined capacitance (S23). Step S23 corresponds to the first detection process.

[0045] For example, the controller 51 designates the group identifier G(1), refers to the table, and closes the third switches 573 of the actuators 88(1), 88(2), 88(p + 1), 88(p + 2) corresponding to the nozzles 80 given the group identifier G(1), that is, the nozzles with nozzle addresses N(1), N(2), M1, M(2), and detects the combined capacitance of the piezoelectric bodies 83 of the actuators 88(1), 88(2), 88(p + 1), 88(p + 2).

[0046] The controller 51 calculates the temperature based on the detected combined capacitance and stores it in the storage unit 50a (S24). The controller 51 calculates a value obtained by subtracting the temperature stored in the storage unit 50a in the previous non-discharge detection process from the temperature stored in the storage unit 50a this time, that is, the subtraction value (S25). When the non-discharge detection process is executed for the first time, the initial temperature stored in the storage unit 50a before the non-discharge detection process is subtracted from the temperature stored in the storage unit 50a this time. The process of calculating the temperature based on the detected combined capacitance in step S24 of the previous non-discharge detection process corresponds to the first calculation process. The process of calculating the temperature based on the detected combined capacitance in step S24 of the current non-discharge detection process corresponds to the second calculation process.

[0047] The controller 51 determines whether the subtracted value is greater than or equal to the threshold value (S26). The threshold value is stored in the storage unit 50a. Step S26 corresponds to the first determination process. When the subtracted value is not greater than or equal to the threshold value (S26: NO), that is, when the temperature rise is not excessive and the subtracted value is not an abnormal value, the controller 51 determines whether the detection of the combined capacity has been completed for all group identifiers, that is, for all groups (S27). When the detection of the combined capacity has not been completed for all groups (S27: NO), the process returns to step S21 to select the next group identifier. When the detection of the combined capacity has been completed for all groups (S27: YES), the controller 51 returns the process to step S4.

[0048] In step S26, when the subtracted value is greater than or equal to the threshold value (S26: YES), that is, when the temperature rise is excessive and the subtracted value is an abnormal value, the controller 51 stores an abnormal value flag in the storage unit 50a corresponding to the group identifier to be detected (S28), that is, sets the abnormal value flag. The controller 51 executes a vibration waveform detection process for each nozzle 80 corresponding to the group identifier for which the abnormal value flag has been set (S29), and proceeds to step S27. The vibration waveform detection process will be described later.

[0049] Note that after the processes of steps S21 to S28 have been executed for all groups first, the vibration waveform detection process may be executed. That is, first, it may be determined whether the subtracted value is greater than or equal to the threshold value for all groups, and then the vibration waveform detection process may be executed for the nozzles 80 of each group for which the abnormal value flag has been set.

[0050] The threshold value in step S26 may be a common value for all group identifiers, or may be a plurality of values corresponding to each group identifier. When there are a plurality of values corresponding to each group identifier, each time a group identifier is specified in step S21, the threshold value corresponding to the specified group identifier is used.

[0051] FIG. 9 is a flowchart for explaining the vibration waveform detection process. The vibration waveform detection process is executed by software installed in the controller 51. The controller 51 designates any nozzle 80 included in the group with the abnormal value flag set (S31), and closes the first switch 571 corresponding to the designated nozzle 80 (S32). The controller 51 outputs a drive signal for a predetermined time (S33), and opens the first switch 571 (S34).

[0052] The controller 51 closes the second switch 572 (S35), detects the vibration waveform (S36), and opens the second switch 572 (S37). The controller 51 determines whether the detected vibration waveform is abnormal (S38). Step S36 corresponds to the second detection process, and step S38 corresponds to the second determination process.

[0053] FIG. 10 is a graph schematically showing the relationship between the viscosity of the ink and the vibration waveform, and FIG. 11 is a graph schematically showing the relationship between the mixing of air bubbles into the ink and the vibration waveform. In the vibration waveform detection process of step S29, the controller 51 detects the vibration waveform generated by the vibration of the piezoelectric body 83.

[0054] As shown in FIG. 10, the amplitude of the vibration waveform varies depending on the viscosity ratio of the ink. When viscosity ratio A < viscosity ratio B < viscosity ratio C, the amplitude of viscosity ratio A is the largest, and the amplitude of viscosity ratio C is the smallest. For example, when the ink near the nozzle 80 dries, the viscosity of the ink increases. When the viscosity of the ink increases, the flow path resistance increases, the vibration period and the decay of the residual vibration become larger, and there is a risk that the ink cannot be ejected from the nozzle 80. The controller 51 calculates the viscosity ratio of the ink based on the vibration waveform, and when the viscosity ratio of the ink is larger than the threshold value stored in the storage unit 50a in advance, that is, when the viscosity ratio is excessively large, it determines that the vibration waveform is abnormal.

[0055] As shown in FIG. 11, the period of the vibration waveform varies depending on whether or not bubbles are mixed into the ink. For example, when bubbles are mixed into the ink flow path or the nozzle tip, the weight of the ink decreases by the amount of the mixed bubbles compared to when the nozzle is normal, and the vibration period becomes shorter. If bubbles are mixed into the ink, there is a risk that the ink cannot be ejected from the nozzle 80. The controller 51 calculates the period of the vibration waveform, and when the calculated period is smaller than the threshold value stored in the storage unit 50a in advance, that is, when bubbles are mixed into the ink, it determines that the vibration waveform is abnormal.

[0056] When the detected vibration waveform is abnormal (S38: YES), the controller 51 stores an abnormal waveform flag in the storage unit 50a corresponding to the nozzle address of the nozzle 80 to be detected (S39). The controller 51 determines whether or not the vibration waveform has been detected for all the nozzles 80 included in the group in which the abnormal value flag is set (S40).

[0057] In step S38, when the detected vibration waveform is not abnormal (S38: NO), the controller 51 proceeds to step S40.

[0058] In step S40, when the vibration waveform has not been detected for all the nozzles 80 (S40: NO), the process returns to step S31. When the vibration waveform has been detected for all the nozzles 80 (S40: YES), the process returns to step S27 (see FIG. 8).

[0059] In Embodiment 1, although the non-ejection detection process and the vibration waveform detection process are executed by software, it is not limited thereto. For example, a first circuit that outputs different signals when the value based on the combined capacitance is an abnormal value and when it is not an abnormal value, and a second circuit that outputs different signals when the vibration waveform is abnormal and when it is not abnormal may be provided. The first circuit and the second circuit are, for example, logic circuits. In this case, the combined capacitance is input to the first circuit, and the first circuit outputs a signal to the controller 51. Also, the vibration waveform is input to the second circuit, and the second circuit outputs a signal to the controller 51. The controller 51 determines the presence or absence of an abnormality based on each input signal.

[0060] In the printing apparatus according to Embodiment 1, based on the value based on the combined capacitance, it is determined whether there is an abnormality in a plurality of nozzles 80 corresponding to a specified group identifier, that is, in a specified nozzle group. Then, the printing apparatus performs an inspection based on the vibration waveform only when it is determined that there is an abnormality, so that the time required for the inspection can be reduced.

[0061] Further, the printing apparatus calculates the temperature of the nozzle group based on the combined capacitance, and when the subtraction value obtained by subtracting the previously calculated temperature (the first temperature detected at the first time point) from the currently calculated temperature (the second temperature detected at the second time point) is equal to or greater than the threshold value, it is determined that the nozzle group includes an abnormal nozzle 80 whose temperature has risen excessively. An inspection based on the vibration waveform is performed only when it is determined that the abnormal nozzle 80 is included, and the time required for the inspection is reduced.

[0062] (Embodiment 2) Hereinafter, the present invention will be described based on the drawings showing the printing apparatus according to Embodiment 2. Among the configurations according to Embodiment 2, the same configurations as those in Embodiment 1 are denoted by the same reference numerals, and detailed descriptions thereof are omitted. FIG. 12 is a flowchart for explaining the non-ejection detection process by the controller 51.

[0063] The controller 51 designates a group identifier for detecting capacitance (S51), closes the third switches 573 of all the nozzles 80 corresponding to the designated group identifier (S52), detects the combined capacitance (S53), and stores the detected combined capacitance in the storage unit 50a (S54). The controller 51 determines whether the combined capacitance has been stored for all the group identifiers, that is, for all the groups (S55). If the combined capacitance has not been stored for all the groups (S55: NO), the process returns to step S51 to select the next group identifier.

[0064] If the combined capacitance has been stored for all the groups (S55: YES), the controller 51 determines the normal range of the combined capacitance based on the combined capacitances of all the stored groups (S56).

[0065] FIG. 13 is a graph schematically showing the relationship between the group identifier and the combined capacitance. As shown in FIG. 13, the combined capacitances corresponding to the respective group identifiers are stored in the storage unit 50a. The controller 51 calculates, for example, a range including 80% or more of the stored combined capacitances, and determines the calculated range as the normal range. Note that the normal range can be arbitrarily set, and a range including 70% or 90% or more of the stored combined capacitances may be set as the normal range.

[0066] The controller 51 designates a group identifier (S57), and the controller 51 determines whether the combined capacitance of the piezoelectric body 83 corresponding to the designated group identifier is greater than the maximum value Cmax of the normal range (S58). If the combined capacitance is not greater than the maximum value Cmax (S58: NO), the controller 51 determines whether the determination in step S58 has been executed for all the group identifiers, that is, for all the groups (S59). If the determination in step S58 has not been executed for all the groups, the controller 51 returns the process to step S57 to designate the next group identifier.

[0067] In step S58, when the combined capacitance is greater than the maximum value Cmax (S58: YES), that is, when the temperature rise is excessive and the combined capacitance is an abnormal value, an abnormal value flag is stored in the storage unit 50a corresponding to the group identifier to be detected (S60), that is, the abnormal value flag is set. The controller 51 executes a vibration waveform detection process for each nozzle 80 corresponding to the group identifier for which the abnormal value flag has been set (S61), and proceeds to step S59.

[0068] In the printing apparatus according to the second embodiment, the combined capacitance of the piezoelectric body 83 corresponding to each group identifier is detected, and a normal range is determined based on the detected combined capacitances. The controller 51 designates any one of the group identifiers, and when the combined capacitance of the designated group identifier is greater than the normal range, it is determined that the plurality of nozzles corresponding to the designated group identifier, that is, the nozzle group, includes the abnormal nozzle 80 in which the temperature has risen excessively. Only when it is determined that the abnormal nozzle 80 is included, an inspection based on the vibration waveform is performed on the nozzle group, and the time required for the inspection is reduced.

[0069] (Embodiment 3) Hereinafter, the present invention will be described based on the drawings showing the printing apparatus according to the third embodiment. Among the configurations according to the third embodiment, the same configurations as those in the first or second embodiment are denoted by the same reference numerals, and detailed descriptions thereof are omitted. FIG. 14 is an explanatory diagram for explaining the relationship between the nozzle address and the group identifier.

[0070] As shown in FIG. 14, the inkjet head 8 includes a first nozzle row 80a and a second nozzle row 80b. The first nozzle row 80a is arranged on the left side, and the second nozzle row 80b is arranged on the right side.

[0071] Nozzle addresses N(1), N(2), ···, N(p) are assigned to each of the plurality of nozzles 80 that make up the first nozzle row 80a. In this embodiment, the nozzle addresses N(1), N(2), ···, N(p) are assigned in order from upstream to downstream. That is, the nozzle 80 with the nozzle address N(1) corresponds to the most upstream nozzle, the nozzle address N(p) corresponds to the most downstream nozzle, the nozzle 80 with the nozzle address N(2) corresponds to the first adjacent nozzle, and the nozzle 80 with the nozzle address N(p - 1) corresponds to the second adjacent nozzle.

[0072] Nozzle addresses M(1), M(2), ···, M(p) are assigned to each of the plurality of nozzles 80 that make up the second nozzle row 80b. In this embodiment, the nozzle addresses M(1), M(2), ···, M(p) are assigned in order from upstream to downstream. That is, the nozzle 80 with the nozzle address M(1) corresponds to the most upstream nozzle, the nozzle address M(p) corresponds to the most downstream nozzle, the nozzle 80 with the nozzle address M(2) corresponds to the first adjacent nozzle, and the nozzle 80 with the nozzle address M(p - 1) corresponds to the second adjacent nozzle.

[0073] As shown in FIG. 14, for example, the group identifier G(1) corresponds to the nozzle addresses N(1) and N(p), the group identifier G(2) corresponds to the nozzle address N(2) and the nozzle address N(p - 1), the group identifier G(3) corresponds to the nozzle address N(3) and the nozzle address N(p - 2), and the group identifier G(4) corresponds to the nozzle address N(4) and the nozzle address N(p - 3). Also in Embodiment 3, as in Embodiment 1 or 2, the state of the nozzle 80 is inspected.

[0074] In the printing apparatus according to Embodiment 3, a group identifier G(1) is assigned to the most upstream nozzle and the most downstream nozzle, and a group identifier G(2) is assigned to the first adjacent nozzle and the second adjacent nozzle. That is, the nozzle closest to the ink supply port 8a and the nozzle farthest from the ink supply port 8a are made to belong to the same group, and then the nozzle closest to the ink supply port 8a and the nozzle farthest from the ink supply port 8a next are made to belong to the same group. Since the temperature of the ink rises as it goes downstream, by performing grouping as described above, the average temperature in each group can be made uniform. Therefore, the difference in the combined capacity of each group becomes small, and it becomes easier to make the threshold value for comparison with the value based on the combined capacity common to each group.

[0075] The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The technical features described in each embodiment can be combined with each other, and the scope of the present invention is intended to include all modifications within the scope of the claims and the scope equivalent to the claims.

Explanation of Signs

[0076] 1 Printing apparatus 51 Controller 80 Nozzle 83 Piezoelectric body 84 Common electrode 85 Individual electrode 88 Actuator

Claims

1. A first nozzle group having a plurality of nozzles including a first nozzle and a second nozzle, a first actuator and a second actuator corresponding to the first nozzle and the second nozzle, and a controller provided with, Each of the first actuator and the second actuator includes a piezoelectric body deformed to discharge liquid from the nozzle, and at least two electrodes sandwiching the piezoelectric body and has, The controller performs a first detection process of detecting a combined capacitance of the piezoelectric bodies of the first actuator and the second actuator, a first determination process of determining whether a value based on the combined capacitance detected in the first detection process is an abnormal value, When it is determined that the value based on the combined capacitance is an abnormal value, a driving process of driving the first actuator and the second actuator, After driving the first actuator and the second actuator, a second detection process of detecting a vibration waveform generated by vibration of the piezoelectric body for each of the piezoelectric bodies of the first actuator and the second actuator, and a second determination process of determining whether the vibration waveform detected in the second detection process is an abnormal waveform are executed Liquid discharge device.

2. The controller performs a first calculation process of calculating a first temperature based on the combined capacitance detected at a first time point, and a second calculation process of calculating a second temperature based on the combined capacitance detected at a second time point after the first time point and executes, In the first determination process, when a subtraction value obtained by subtracting the first temperature from the second temperature is equal to or greater than a threshold value, it is determined that the subtraction value is an abnormal value The liquid discharge device according to claim 1.

3. A first nozzle group having a plurality of nozzles including a first nozzle and a second nozzle, a first actuator and a second actuator corresponding to the first nozzle and the second nozzle, and a controller provided, each of the first actuator and the second actuator includes a piezoelectric body deformed to discharge liquid from the nozzle, and at least two electrodes sandwiching the piezoelectric body and has, the controller a first detection process for detecting the combined capacitance of the piezoelectric bodies of the first actuator and the second actuator, a first determination process for determining whether a value based on the combined capacitance detected in the first detection process is an abnormal value, when it is determined that the value based on the combined capacitance is an abnormal value, a drive process for driving the first actuator and the second actuator, after driving the first actuator and the second actuator, a second detection process for detecting a vibration waveform generated by the vibration of the piezoelectric body for each of the piezoelectric bodies of the first actuator and the second actuator, and a second determination process for determining whether the vibration waveform detected in the second detection process is an abnormal waveform and executes, including a plurality of k-th nozzle groups (k = 1, 2,..., n, n is a natural number of 3 or more) including the first nozzle group and a second nozzle group having a plurality of nozzles including a third nozzle and a fourth nozzle, the controller in the first detection process, for each of the plurality of k-th nozzle groups, detects the combined capacitance, in the first determination process, a process of determining a normal range that is a range of values based on the combined capacitance and in which the combined capacitance of each of the plurality of k-th nozzle groups is included at a predetermined ratio or more, A process for determining whether a value based on the combined capacitance of the first nozzle group is within the normal range, and a process for determining that the value is an abnormal value when the value based on the combined capacitance of the first nozzle group is not within the normal range are executed. Liquid ejection device. **Claim 4** Comprising a manifold through which liquid flows, wherein the first nozzle of the first nozzle group is the most upstream nozzle located at the most upstream of the manifold, and the second nozzle of the first nozzle group is the most downstream nozzle located at the most downstream of the manifold. The liquid ejection device according to claim 2 or 3. **Claim 5** A first nozzle group having a plurality of nozzles including a first nozzle and a second nozzle, a first actuator and a second actuator corresponding to the first nozzle and the second nozzle, and a controller are provided. Each of the first actuator and the second actuator has a piezoelectric body deformed to eject liquid from the nozzle, and at least two electrodes sandwiching the piezoelectric body. The controller performs a first detection process for detecting the combined capacitance of the piezoelectric bodies of the first actuator and the second actuator, a first determination process for determining whether a value based on the combined capacitance detected in the first detection process is an abnormal value, a drive process for driving the first actuator and the second actuator when it is determined that the value based on the combined capacitance is an abnormal value, and a second detection process for detecting, for each of the piezoelectric bodies of the first actuator and the second actuator, a vibration waveform generated by the vibration of the piezoelectric body after driving the first actuator and the second actuator. ​A second determination process for determining whether or not the vibration waveform detected in the second detection process is an abnormal waveform is executed, A plurality of k-th nozzle groups (k = 1, 2,..., n, where n is a natural number of 3 or more) including the first nozzle group and a second nozzle group having a plurality of nozzles including the third nozzle and the fourth nozzle are provided, The controller, In the first detection process, for each of the plurality of k-th nozzle groups, the combined capacitance is detected, In the first determination process, A process of determining a normal range that is a range of values based on the combined capacitance and in which the combined capacitance of each of the plurality of k-th nozzle groups is included at a predetermined ratio or more, A process of determining whether or not a value based on the combined capacitance of the first nozzle group is within the normal range, When the value based on the combined capacitance of the first nozzle group is not within the normal range, a process of determining that the value is an abnormal value is executed, A manifold through which a liquid flows is provided, The first nozzle of the first nozzle group is the most upstream nozzle located at the most upstream of the manifold, and the second nozzle of the first nozzle group is the most downstream nozzle located at the most downstream of the manifold, The third nozzle of the second nozzle group is the first proximity nozzle located closest to the most upstream nozzle, and the fourth nozzle of the second nozzle group is the second proximity nozzle located closest to the most downstream nozzle, The k-th nozzle group (k is a natural number of 3 or more) includes a nozzle located one downstream of the nozzle located most upstream among the nozzles of the (k - 1)-th nozzle group and a nozzle located one upstream of the nozzle located most downstream among the nozzles of the (k - 1)-th nozzle group A liquid ejection device.

6. A manifold through which a liquid flows is provided, The first nozzle of the first nozzle group is the most upstream nozzle located at the most upstream of the manifold, and the second nozzle of the first nozzle group is the first proximity nozzle located at the position closest to the most upstream nozzle. The third nozzle of the second nozzle group is the third proximity nozzle located at the position closest to the most upstream nozzle next to the first proximity nozzle, and the fourth nozzle of the second nozzle group is the fourth proximity nozzle located at the position closest to the most upstream nozzle next to the third proximity nozzle. The liquid ejection device according to claim 3.

7. A first detection circuit for detecting the combined capacitance of the piezoelectric bodies of the first actuator and the second actuator; A second detection circuit for detecting a vibration waveform generated by the vibration of the piezoelectric body after driving the first actuator or the second actuator; A first switching element connected to the first actuator and the first detection circuit; A second switching element connected to the second actuator and the first detection circuit; A third switching element connected to the first actuator and the second detection circuit; A fourth switching element connected to the second actuator and the second detection circuit; comprising The liquid ejection device according to any one of claims 1 to 6.

8. The controller closes the first switching element and the second switching element, and detects the combined capacitance of the piezoelectric bodies of the first actuator and the second actuator by the first detection circuit; closes the third switching element, opens the fourth switching element, and detects the vibration waveform in the first actuator by the second detection circuit; closes the fourth switching element, opens the third switching element, and detects the vibration waveform in the second actuator by the second detection circuit. The liquid ejection device according to claim 7.

9. A control method for a liquid ejection device, comprising: a first nozzle group having a plurality of nozzles including a first nozzle and a second nozzle; a first actuator and a second actuator corresponding to the first nozzle and the second nozzle; and a controller, wherein each of the first actuator and the second actuator has a piezoelectric body deformed to eject liquid from the nozzle and at least two electrodes sandwiching the piezoelectric body, and the method comprises: The controller a first detection process of detecting a combined capacitance of the piezoelectric bodies of the first actuator and the second actuator; a first determination process of determining whether a value based on the combined capacitance detected in the first detection process is an abnormal value; when it is determined that the value based on the combined capacitance is an abnormal value, a driving process of driving the first actuator and the second actuator; after driving the first actuator and the second actuator, a second detection process of detecting a vibration waveform generated by vibration of the piezoelectric body for each of the piezoelectric bodies of the first actuator and the second actuator; a second determination process of determining whether the vibration waveform detected in the second detection process is an abnormal waveform A control method for a liquid ejection device that executes the above.

10. A control method for a liquid ejection device, comprising: a first nozzle group having a plurality of nozzles including a first nozzle and a second nozzle; a first actuator and a second actuator corresponding to the first nozzle and the second nozzle; and a controller, wherein each of the first actuator and the second actuator has a piezoelectric body deformed to eject liquid from the nozzle and at least two electrodes sandwiching the piezoelectric body, and the method comprises: The controller a first detection process of detecting a combined capacitance of the piezoelectric bodies of the first actuator and the second actuator; A first determination process for determining whether a value based on the combined capacitance detected in the first detection process is an abnormal value, When it is determined that the value based on the combined capacitance is an abnormal value, a drive process for driving the first actuator and the second actuator, After driving the first actuator and the second actuator, a second detection process for detecting a vibration waveform generated by the vibration of the piezoelectric body for each of the piezoelectric bodies of the first actuator and the second actuator, A second determination process for determining whether the vibration waveform detected in the second detection process is an abnormal waveform, and The liquid discharge device A first nozzle group having a plurality of nozzles including a first nozzle and a second nozzle, A first actuator and a second actuator corresponding to the first nozzle and the second nozzle, A controller And Each of the first actuator and the second actuator A piezoelectric body deformed to discharge liquid from the nozzle, At least two electrodes sandwiching the piezoelectric body And The controller A first detection process for detecting the combined capacitance of the piezoelectric bodies of the first actuator and the second actuator, A first determination process for determining whether a value based on the combined capacitance detected in the first detection process is an abnormal value, When it is determined that the value based on the combined capacitance is an abnormal value, a drive process for driving the first actuator and the second actuator, After driving the first actuator and the second actuator, a second detection process for detecting a vibration waveform generated by the vibration of the piezoelectric body for each of the piezoelectric bodies of the first actuator and the second actuator, A second determination process for determining whether or not the vibration waveform detected in the second detection process is an abnormal waveform is executed, A plurality of k-th nozzle groups (k = 1, 2,..., n) including a first nozzle group and a second nozzle group having a plurality of nozzles including a third nozzle and a fourth nozzle are provided, The controller, In the first detection process, for each of the plurality of k-th nozzle groups, the combined capacitance is detected, In the first determination process, A process of determining a normal range that is a range of values based on the combined capacitance and in which the combined capacitance of each of the plurality of k-th nozzle groups is included at a predetermined ratio or more, A process of determining whether or not a value based on the combined capacitance of the first nozzle group is within the normal range, When the value based on the combined capacitance of the first nozzle group is not within the normal range, a process of determining that the value is an abnormal value A control method for a liquid ejection device that executes.

11. A control method for a liquid ejection device including a first nozzle group having a plurality of nozzles including a first nozzle and a second nozzle, a first actuator and a second actuator corresponding to the first nozzle and the second nozzle, and a controller, wherein each of the first actuator and the second actuator has a piezoelectric body deformed to eject liquid from the nozzle and at least two electrodes sandwiching the piezoelectric body, The controller, A first detection process for detecting the combined capacitance of the piezoelectric bodies of the first actuator and the second actuator, A first determination process for determining whether or not a value based on the combined capacitance detected in the first detection process is an abnormal value, When it is determined that the value based on the combined capacitance is an abnormal value, a driving process for driving the first actuator and the second actuator, After driving the first actuator and the second actuator, a second detection process for detecting a vibration waveform generated by the vibration of the piezoelectric body for each of the piezoelectric bodies of the first actuator and the second actuator, a second determination process for determining whether or not the vibration waveform detected in the second detection process is an abnormal waveform, and the liquid ejection device has a first nozzle group having a plurality of nozzles including a first nozzle and a second nozzle, a first actuator and a second actuator corresponding to the first nozzle and the second nozzle, and a controller and each of the first actuator and the second actuator has a piezoelectric body deformed to eject liquid from the nozzle, and at least two electrodes sandwiching the piezoelectric body and the controller performs a first detection process for detecting a combined capacitance of the piezoelectric bodies of the first actuator and the second actuator, a first determination process for determining whether or not a value based on the combined capacitance detected in the first detection process is an abnormal value, when it is determined that the value based on the combined capacitance is an abnormal value, a driving process for driving the first actuator and the second actuator, after driving the first actuator and the second actuator, a second detection process for detecting a vibration waveform generated by the vibration of the piezoelectric body for each of the piezoelectric bodies of the first actuator and the second actuator, a second determination process for determining whether or not the vibration waveform detected in the second detection process is an abnormal waveform and performs, and includes a plurality of k-th nozzle groups (k = 1, 2,..., n) including the first nozzle group and a second nozzle group having a plurality of nozzles including a third nozzle and a fourth nozzle, the controller In the first detection process, for each of the plurality of k-th nozzle groups, detect the combined capacity, In the first determination process, Determine a normal range that is a range of values based on the combined capacity and in which the combined capacity of each of the plurality of k-th nozzle groups is included at a predetermined ratio or more, Determine whether a value based on the combined capacity of the first nozzle group is within the normal range, When the value based on the combined capacity of the first nozzle group is not within the normal range, execute a process of determining that the value is an abnormal value, The liquid ejection device includes a manifold through which liquid flows, The first nozzle of the first nozzle group is the most upstream nozzle located at the most upstream of the manifold, and the second nozzle of the first nozzle group is the most downstream nozzle located at the most downstream of the manifold, The third nozzle of the second nozzle group is the first proximity nozzle located closest to the most upstream nozzle, and the fourth nozzle of the second nozzle group is the second proximity nozzle located closest to the most downstream nozzle, The k-th nozzle group (k is a natural number of 3 or more) includes a nozzle located one downstream of the nozzle located most upstream among the nozzles of the (k - 1)-th nozzle group and a nozzle located one upstream of the nozzle located most downstream among the nozzles of the (k - 1)-th nozzle group, A control method for a liquid ejection device.

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