Storage amount detection device and liquid ejection device

Abstract

To avoid an increase in size of a circuit board to accurately determine a storage amount.SOLUTION: A storage amount detection device comprises: a storage unit that has a first surface and a second surface separated in a first direction from the first surface, and can store an object between the first surface and the second surface; a transmission electrode that is provided on the first surface; a first reception electrode that is provided on the second surface; a second reception electrode that is provided on the second surface; an output terminal; a selector circuit that switches whether to electrically connect the output terminal to at least one of the first reception electrode and the second reception electrode; and a detection circuit that detects the amount of the object stored in the storage unit based on an output from the output terminal.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a storage amount detection device and a liquid ejection device. [Background technology]

[0002] There is known a remaining amount detection sensor that detects the remaining amount of the contents of a container (for example, Patent Document 1). This remaining amount detection sensor includes a detection electrode arranged opposite the container and a guard electrode arranged opposite the detection electrode and connected to a reference potential, and detects the remaining amount of the contents of the container based on the electrostatic capacitance measured by the detection electrode. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-230227 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology described in Patent Document 1, one remaining amount detection circuit is electrically connected to a detection electrode. In this case, if multiple detection electrodes are provided, a remaining amount detection circuit needs to be provided for each detection electrode, which causes a problem of an increase in the size of the circuit board. [Means for solving the problem]

[0005] The storage amount detection device of the present invention comprises a storage section having a first surface and a second surface spaced apart from the first surface in a first direction and capable of storing an object between the first surface and the second surface, a transmitting electrode provided on the first surface, a first electrode provided on the second surface, a second electrode provided on the second surface, an output terminal, a selector circuit that switches whether or not the output terminal is electrically connected to at least one of the first receiving electrode and the second receiving electrode, and a detection circuit that detects the amount of the object stored in the storage section based on the output from the output terminal.

[0006] A liquid ejection device according to the present invention includes the storage amount detection device described above and an ejection section that ejects the liquid. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic diagram of a liquid ejection device according to a first embodiment. [Diagram 2] 1 is a schematic diagram of a storage amount detection device according to a first embodiment. [Diagram 3] FIG. [Figure 4] 1 is a graph showing the relationship between the liquid level and the output voltage from a capacitor. [Diagram 5] FIG. 2 is a circuit diagram of the storage amount detection device. [Figure 6] FIG. 2 is a block diagram of a storage amount detection device. [Figure 7] 4 is a flowchart showing the operation of a selector circuit. [Figure 8] FIG. 2 is a circuit diagram including a selector circuit. [Figure 9] 11 is a circuit diagram showing the connection relationship between a receiving electrode that is not connected to an output terminal and a constant voltage terminal. FIG. [Figure 10] 11 is a circuit diagram showing the connection relationship between a receiving electrode that is not connected to an output terminal and a constant voltage terminal. FIG. [Figure 11] 11 is a circuit diagram showing the connection relationship between a receiving electrode that is not connected to an output terminal and a constant voltage terminal. FIG. [Figure 12]FIG. 13 is a cross-sectional view showing a reservoir provided with a shield electrode. [Figure 13] FIG. 13 is a cross-sectional view taken along the line AA in FIG. [Figure 14] FIG. 2 is a diagram showing a transmitting electrode and a shield electrode. [Figure 15] FIG. 2 is a diagram showing a receiving electrode and a shield electrode. [Figure 16] FIG. 2 is a cross-sectional view of the reservoir illustrating electric field lines emanating from a transmitting electrode. [Figure 17] FIG. 4 is a diagram showing electric field lines received by a receiving electrode. [Figure 18] FIG. 13 is a cross-sectional view of multiple reservoirs illustrating electric field lines emanating from multiple transmitting electrodes. [Figure 19] 4 is a flowchart showing a processing procedure of the storage amount detection device. [Figure 20] 10 is a flowchart showing a procedure in a noise detection mode. [Figure 21] 10 is a flowchart showing a procedure in a liquid level measurement mode. [Figure 22] 6 is a flowchart showing a processing procedure of a storage amount detection device according to a first modified example. [Diagram 23] FIG. 11 is a circuit diagram showing the operation of a selector circuit according to a second modified example. [Figure 24] FIG. 11 is a circuit diagram showing the operation of a selector circuit according to a second modified example. [Diagram 25] FIG. 11 is a circuit diagram showing the operation of a selector circuit according to a second modified example. [Figure 26] FIG. 11 is a schematic diagram of a liquid ejection device according to a second embodiment. [Figure 27] FIG. 6 is a schematic diagram of a storage amount detection device according to a second embodiment. [Figure 28] FIG. 13 is a circuit diagram showing the operation of a selector circuit according to a third modified example. [Figure 29] FIG. 13 is a circuit diagram showing the operation of a selector circuit according to a third modified example. [Diagram 30] 13 is a flowchart showing a procedure for error determination in a detection circuit according to a third modified example. [Diagram 31] 11 is a table showing the relationship between the output voltage Vout and the detection result. [Diagram 32] 11 is a table showing the relationship between the output voltage Vout and the detection result. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the embodiments of the present invention will be described with reference to the drawings. However, in each drawing, the dimensions and scale of each part are appropriately different from the actual ones. In addition, since the embodiments described below are preferred specific examples of the present invention, various technically preferable limitations are attached, but the scope of the present invention is not limited to these embodiments unless otherwise specified in the following description to the effect that the present invention is limited.

[0009] 1 is a schematic diagram of a liquid ejection device 1A equipped with a storage amount detection device 20A. The liquid ejection device 1A is an inkjet printer that ejects ink 2 to form an image on recording paper P. The ink 2 is an example of a "liquid," and the recording paper P is an example of a "medium." The storage amount detection device 20A detects the amount of ink 2 stored in a storage unit 21A.

[0010] Print data indicating an image to be formed by the liquid ejection device 1A is supplied to the liquid ejection device 1A from a host computer such as a personal computer or a digital camera. The liquid ejection device 1A executes a print process to form on recording paper P an image indicated by the print data supplied from the host computer.

[0011] The liquid ejection device 1A is a serial printer. Specifically, when performing a printing process, the liquid ejection device 1A ejects ink 2 from an ejection unit 4 while transporting a recording paper P in a sub-scanning direction and reciprocating a head unit 3 in a main scanning direction intersecting the sub-scanning direction, thereby forming dots on the recording paper P according to the print data.

[0012] In Fig. 1, the X-axis direction, the Y-axis direction, and the Z-axis direction are illustrated. The X-axis direction is a direction along the sub-scanning direction. The Y-axis direction is a direction along the main scanning direction. The Z-axis direction is a direction along the height direction. The Y-axis direction is an example of a first direction that intersects with the height direction.

[0013] The liquid ejection device 1A includes a housing 5, a carriage 6, and a transport unit 7. When a printing process is performed, the transport unit 7 reciprocates the carriage 6 in the Y-axis direction and transports the recording paper P in the X-axis direction, thereby changing the relative position of the recording paper P with respect to the head unit 3 and enabling the ink 2 to land on the entire recording paper P. The transport unit 7 includes a carriage transport mechanism 8 for reciprocating the carriage 6, and a medium transport mechanism 9 for transporting the recording paper P.

[0014] The liquid ejection device 1A includes a medium storage unit 10 that stores recording paper P. The recording paper P is supplied from the medium storage unit 10 to a medium transport mechanism 9, and transported to the vicinity of the head unit 3.

[0015] The liquid ejection device 1A includes a notification unit 11. The notification unit 11 includes a liquid crystal display device. The notification unit 11 may be configured to notify by sound, vibration, or a blinking pattern of a lamp. A device with a communication function such as a computer screen or a smartphone may function as the notification unit. The notification unit 11 displays the detection result by a detection circuit 63 described later. The notification unit 11 can display other information.

[0016] Fig. 2 is a schematic diagram of the storage amount detection device 20A. Fig. 3 is a cross-sectional view of the storage unit 21A. As shown in Fig. 2, the storage amount detection device 20A includes the storage unit 21A, a transmitting electrode 22, a receiving electrode 30, a detection unit 50, and a control unit 60. The control unit 60 also functions as a control unit for each unit of the liquid ejection device 1A.

[0017] As shown in Fig. 3, the storage unit 21A has a cylindrical body 25, a bottom plate 26, and a top plate 27. The cylindrical body 25 includes a side plate 28 and a side plate 29 that are spaced apart in the Y-axis direction. The cylindrical body 25 includes a plurality of side plates (not shown) that are spaced apart in the X-axis direction. The bottom plate 26 is disposed so as to close an opening at the bottom of the cylindrical body 25. The top plate 27 closes an opening at the top of the cylindrical body 25. The space inside the cylindrical body 25 is a space for storing liquid.

[0018] The constituent material of the storage portion 21A is not particularly limited as long as it is impermeable to the ink 2 and is made of a dielectric material, and for example, various resin materials such as polyolefin, polycarbonate, polyester, etc. and various glass materials can be used. In addition, the storage portion 21A may be hard or soft, or may be partially hard and the remaining portion soft.

[0019] A discharge port (not shown) is formed in the bottom plate 26. Liquid stored in the storage section 21A is discharged through the discharge port. The discharge port is connected to the discharge section 4 of the head unit 3. When the ink 2 is discharged from the head unit 3, the amount of ink 2 stored in the storage section 21A decreases and the liquid level L drops. The storage amount detection device 20A detects the liquid level L of the ink 2 and can grasp the remaining amount of ink 2. The notification section 11 displays the remaining amount of ink 2 and notifies the user, thereby preventing the ink 2 from running out at an undesired time.

[0020] A transmitting electrode 22 is provided on an outer surface 28a of a side plate 28 of the storage unit 21A. The outer surface 28a of the side plate 28 is an example of a first surface of the storage unit 21A. A receiving electrode 30 is provided on an outer surface 29a of a side plate 29 of the storage unit 21A. The outer surface 29a of the side plate 29 is an example of a second surface of the storage unit 21A. The first surface and the second surface of the storage unit may be spaced apart in the X-axis direction, the Y-axis direction, or another direction.

[0021] The receiving electrode 30 includes receiving electrodes 31 to 33. The receiving electrode 31 is an example of a first receiving electrode. The receiving electrode 32 is an example of a second receiving electrode. The receiving electrode 33 is an example of a third receiving electrode.

[0022] The transmitting electrode 22 and the receiving electrodes 31 to 33 are made of a conductive material, for example, a metallic material such as gold, silver, copper, aluminum, iron, nickel, cobalt, or an alloy containing these. The transmitting electrode 22 and the receiving electrodes 31 to 33 may be formed directly on the outer surfaces of the side plates 28, 29 by, for example, plating, vapor deposition, printing, or the like, or may be attached to the outer surfaces of the side plates 28, 29 via an adhesive layer (not shown), or may be supported by a supporting member (not shown) in contact with or without contact with the side plates 28, 29.

[0023] The receiving electrodes 31-33 are disposed at positions overlapping with the transmitting electrode 22 when viewed from the X-axis direction. The receiving electrodes 31-33 are disposed at different positions in the height direction. The receiving electrode 31 is disposed at a higher position than the receiving electrodes 32 and 33, and the receiving electrode 32 is disposed at a higher position than the receiving electrode 33. Note that the receiving electrode 31 may be disposed at a lower position than the receiving electrodes 32 and 33, and the receiving electrode 32 may be disposed at a lower position than the receiving electrode 33. Note that the "height direction" is the direction along the up-down direction when the liquid ejecting device 1A is in a normal usage state.

[0024] The receiving electrode 31 is disposed at a height position H1. The height position H1 is an example of a first height position. For example, the center position of the receiving electrode 31 in the height direction is disposed at the height position H1. Note that the lower end of the receiving electrode 31 may be disposed at the height position H1, or other portions of the receiving electrode 31 may be disposed at the height position H1.

[0025] The receiving electrode 32 is disposed at a height position H2. The height position H2 is an example of a second height position. For example, the center position of the receiving electrode 32 in the height direction is disposed at the height position H2. Note that the lower end of the receiving electrode 32 may be disposed at the height position H2, or other portions of the receiving electrode 32 may be disposed at the height position H2.

[0026] The receiving electrode 33 is disposed at a height position H3. The height position H3 is an example of a third height position. For example, the center position of the receiving electrode 33 in the height direction is disposed at the height position H3. Note that the lower end of the receiving electrode 33 may be disposed at the height position H3, or other portions of the receiving electrode 33 may be disposed at the height position H3.

[0027] The transmitting electrode 22 and the receiving electrode 31 form parallel plates and constitute a capacitor 71. The transmitting electrode 22 and the receiving electrode 32 form parallel plates and constitute a capacitor 72. The transmitting electrode 22 and the receiving electrode 33 form parallel plates and constitute a capacitor 73. The capacitors 71 to 73 may have the same structure or different structures.

[0028] The capacitance C [F] of the capacitors 71 to 73 is expressed by the following formula (1). C=ε 0 ε 1 S / d…(1) ε 0 is the dielectric constant of a vacuum. ε 1 is the relative dielectric constant of the object between the electrodes of the capacitors 71 to 73. The capacitance C of the capacitors 71 to 73 is the relative dielectric constant ε 1 It depends on the relative dielectric constant ε 1 varies depending on the ratio of the ink 2 and air present between the electrodes of the capacitors 71 to 73. ink is the relative dielectric constant of air, ε air Larger than the dielectric constant of ink 2, ε air is, for example, 80, and the relative dielectric constant of air, ε air is almost zero.

[0029] The AC power source 12 is electrically connected to the transmitting electrode 22. The AC power source 12 outputs a pulse wave of, for example, 3.3 [V] as a transmission signal to the transmitting electrode 22. FIG. 4 is a graph showing the relationship between the liquid level of the ink 2 and the output voltage of the capacitors 71-73. The horizontal axis shows the liquid level of the ink 2, with the liquid level increasing toward the right in the figure. The vertical axis shows the output voltage [V] of the capacitor, with the voltage increasing toward the top in the figure.

[0030] The liquid level range LV1 is the range in the height direction from the lower end to the upper end of the condenser 71. The liquid level range LV2 is the range in the height direction from the lower end to the upper end of the condenser 72. The liquid level range LV3 is the range in the height direction from the lower end to the upper end of the condenser 73. The liquid level range LV1 is set at the highest position, followed by the liquid level range LV2 and the liquid level range LV3, which are lower in this order.

[0031] When air is present between the electrodes of the capacitors 71 to 73 and ink 2 is not present, the output voltage V out V L [V]. As the proportion of ink 2 present between the electrodes of the capacitors 71 to 73 increases, the output voltage V out When the electrodes of the capacitors 71 to 73 are filled with ink 2 and no air is present, the output voltage V out V H [V]. For example, the output voltage V out is a given threshold V th When the threshold value V th V L That's all, V H The following values ​​are available: For example, V L to 0% and V H When the threshold value V is set to 100[%], th may be a value of 50%, a value of 30%, a value of 70%, or some other value.

[0032] Output voltage V from capacitor 71 31 is the threshold V th When the liquid level L of the ink 2 is in the liquid level range LV1, the output voltage V 32 is the threshold V th When the liquid level L of the ink 2 is in the liquid level range LV2, the output voltage V 33 is the threshold V th In this case, the liquid level L of the ink 2 is in the liquid level range LV3.

[0033] Next, the detection unit 50 will be described. FIG. 5 is a circuit diagram of the storage amount detection device 20A. FIG. 6 is a block diagram of the storage amount detection device 20A. As shown in FIG. 5, the detection unit 50 includes a selector circuit 36A, a buffer circuit 51, a BPF 52, an S / H 53, an LPF 54, and an amplifier circuit 55. The detection unit 50 has a filter circuit 37 that removes a predetermined frequency component from the input electrical signal. The detection unit 50 has the BPF 52 and the LPF 54 as the filter circuit 37.

[0034] The selector circuit 36A is electrically connected to the input terminals 41 to 43 and the output terminal 40A. The input terminal 41 is an example of a first input terminal. The input terminal 42 is an example of a second input terminal. The input terminal 43 is an example of a third input terminal. The input terminal 41 is electrically connected to the receiving electrode 31. The input terminal 42 is electrically connected to the receiving electrode 32. The input terminal 43 is electrically connected to the receiving electrode 33.

[0035] The selector circuit 36A switches whether or not the output terminal 40A is electrically connected to at least one of the input terminals 41 to 43. The output terminal 40A is electrically connected to at least one of the input terminals 41 to 43. The selector circuit 36A electrically connects the input terminal 41 and the output terminal 40A, thereby electrically connecting the receiving electrode 31 and the output terminal 40A. The selector circuit 36A electrically connects the input terminal 42 and the output terminal 40A, thereby electrically connecting the receiving electrode 32 and the output terminal 40A. The selector circuit 36A electrically connects the input terminal 43 and the output terminal 40A, thereby electrically connecting the receiving electrode 33 and the output terminal 40A. In this way, the selector circuit 36A switches whether or not the output terminal 40A is electrically connected to at least one of the receiving electrodes 31 to 33. A bias circuit 48 is electrically connected to the rear stage of the selector circuit 36A.

[0036] The buffer circuit 51 is electrically connected to the rear stage of the selector circuit 36A. The buffer circuit 51 is electrically connected to the output terminal 40A of the selector circuit 36A. Since the impedance of the receiving electrodes 31 to 33 is high, the buffer circuit 51 performs impedance conversion.

[0037] The BPF 52 includes a band-pass filter circuit. The BPF 52 is electrically connected to the rear stage of the buffer circuit 51. The BPF 52 passes frequency components in a predetermined band of the input electrical signal and removes frequency components in other bands.

[0038] The S / H 53 includes a sample-and-hold circuit. The S / H 53 is electrically connected to the rear stage of the BPF 52. The S / H 53 inputs the electrical signal output from the BPF 52. The S / H 53 samples the electrical signal at predetermined intervals and holds the electrical signal at a constant value until the A / D conversion operation is completed. The S / H 53 is also electrically connected to the AC power supply 12. A 3.3V pulse wave is input to the S / H 53 from the AC power supply 12.

[0039] The LPF 54 includes a low-pass filter circuit. The LPF 54 is electrically connected to the rear stage of the S / H 53. The LPF 54 inputs the electrical signal output from the S / H 53. The LPF 54 removes high-frequency components from the input electrical signal. Noise contained in the high-frequency components is removed by the LPF 54.

[0040] The amplifier circuit 55 is electrically connected to the rear stage of the LPF 54. The electrical signal output from the LPF 54 is input to the amplifier circuit 55. The amplifier circuit 55 amplifies the input electrical signal. The amplified electrical signal is input to the control unit 60 at the rear stage.

[0041] The detection unit 50 includes an A / D converter 38. The A / D converter 38 converts an analog electrical signal, which is an input electrical signal, into a digital electrical signal. The analog electrical signal input to the A / D converter 38 is converted into a digital electrical signal and output. The A / D converter 38 is connected to the rear stage of the amplifier circuit 55. The digital electrical signal output from the A / D converter 38 is input to the control unit 60.

[0042] Next, the control unit 60 will be described. As shown in Fig. 6, the control unit 60 includes a processing circuit 61, such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array), and a storage circuit 62, such as a semiconductor memory. The storage circuit 62 stores a control program and various parameters used to calculate the storage amount of the ink 2. The storage circuit 62 also functions as a working area for the processing circuit 61. The processing circuit 61 reads out the control program from the storage circuit 62. The processing circuit 61 executes the read out control program, thereby functioning as the control center of the liquid ejection device 1A.

[0043] The control unit 60 includes a detection circuit 63. The detection circuit 63 detects the amount of ink 2 stored in the storage unit 21A based on the output from the output terminal 40A. The detection circuit 63 detects the amount of ink 2 stored based on a determination result based on the output from the output terminal 40A when the output terminal 40A and the receiving electrode 31 are connected, a determination result based on the output from the output terminal 40A when the output terminal 40A and the receiving electrode 32 are connected, and a determination result based on the output from the output terminal 40A when the output terminal 40A and the receiving electrode 33 are connected. The detection result of the amount of ink 2 stored by the detection circuit 63 will be described later with reference to FIG. 31.

[0044] Next, a description will be given of the determination result based on the output from the output terminal 40A when the output terminal 40A and the receiving electrode 31 are connected. The detection circuit 63 determines whether the stored amount of ink 2 is equal to or greater than the first amount based on the electrical signal output from the output terminal 40A when the receiving electrode 31 is connected. The detection circuit 63 detects the output voltage V 31 is the threshold V th , the detection circuit 63 determines that the liquid level L is equal to or higher than the height position H1 and that the stored amount of ink 2 is equal to or higher than the first amount. When the liquid level L is equal to or higher than the height position H1, the detection circuit 63 determines that the liquid level L is equal to or higher than the first amount. When the liquid level L is below the height position H1, the detection circuit 63 determines that the liquid level L is less than the first amount. By detecting the height position of the liquid level L of the ink 2, the stored amount of ink 2 can be detected. The detection circuit 63 detects the liquid level L based on a threshold value V th The height position of the liquid level L may be set arbitrarily according to the value of the output voltage V 31 is the threshold V th If the stored amount of ink 2 exceeds the first amount, it may be determined that the stored amount of ink 2 is the first amount.

[0045] Next, a description will be given of the determination result based on the output from the output terminal 40A when the output terminal 40A and the receiving electrode 32 are connected. The detection circuit 63 determines whether or not the stored amount of ink 2 is equal to or greater than the second amount based on the output from the output terminal 40A when the receiving electrode 32 is connected. The detection circuit 63 detects the output voltage V 32 is the threshold V th If the liquid level L exceeds the height position H2, the detection circuit 63 determines that the liquid level L is equal to or higher than the height position H2 and that the stored amount of ink 2 is equal to or higher than the second amount. If the liquid level L is equal to or higher than the height position H2, the detection circuit 63 determines that the liquid level L is equal to or higher than the second amount. If the liquid level L is below the height position H2, the detection circuit 63 determines that the liquid level L is less than the second amount.

[0046] Next, a description will be given of the determination result based on the output from the output terminal 40A when the output terminal 40A and the receiving electrode 33 are connected. The detection circuit 63 determines whether the stored amount of the ink 2 is equal to or greater than a third amount based on the output from the output terminal 40A when the receiving electrode 33 is connected. The detection circuit 63 detects the output voltage V 33 is the threshold V th If the liquid level L exceeds the height position H3, the detection circuit 63 determines that the liquid level L is equal to or greater than the height position H3 and that the stored amount of ink 2 is equal to or greater than the third amount. If the liquid level L is equal to or greater than the height position H3, the detection circuit 63 determines that the liquid level L is equal to or greater than the third amount. If the liquid level L is below the height position H3, the detection circuit 63 determines that the liquid level L is less than the third amount.

[0047] Next, a case where the detection result of the stored amount is an error will be described. For example, if the determination result based on the output from output terminal 40A contains an error, the detection result of the stored amount based on this determination result will be an error. Detection circuit 63 determines that the detection result of the stored amount is an error when it is determined that the stored amount of ink 2 is equal to or greater than a first amount based on the output from output terminal 40A with receiving electrode 31 connected, and when it is determined that the stored amount of ink 2 is less than a third amount based on the output from output terminal 40A with receiving electrode 32 connected.

[0048] The detection circuit 63 determines that the stored amount of ink 2 is less than a first amount based on the electrical signal output from the output terminal 40A when the receiving electrode 31 is connected, determines that the stored amount of ink 2 is a second amount or more based on the electrical signal output from the output terminal 40A when the receiving electrode 32 is connected, and determines that the stored amount of ink 2 is less than a third amount based on the electrical signal output from the output terminal 40A when the receiving electrode 33 is connected.

[0049] The notification unit 11 is electrically connected to the control unit 60, and displays the detection result by the detection circuit 63. The notification unit 11 displays the stored amount of ink 2. The notification unit 11 displays an error message indicating that the detection result of the stored amount is an error.

[0050] Next, the operation of the selector circuit 36A will be described with reference to Fig. 7. Fig. 7 is a circuit diagram including the selector circuit 36A. The selector circuit 36A has switches SW1 to SW3. The selector circuit 36A receives selection signals SG1 to SG3, and switches the receiving electrodes 31 to 33 used to detect the liquid level L in accordance with the received selection signals SG1 to SG3. Note that the selector circuit 36A may switch the receiving electrodes 31 to 33 in accordance with other states, regardless of the selection signals SG1 to SG3.

[0051] The switch SW1 is provided between the input terminal 41 and the output terminal 40A. The switch SW2 is provided between the input terminal 42 and the output terminal 40A. The switch SW3 is provided between the input terminal 43 and the output terminal 40A.

[0052] The selector circuit 36A is electrically connected to a decoder DC1. The control unit 60 transmits command signals SG-A and SG-B to the decoder DC1, which specify one of the receiving electrodes 31 to 33 to be used for measuring the liquid level L of the ink 2.

[0053] When the command signals SG-A and SG-B designate the receiving electrode 31, the decoder DC1 sets the selection signal SG1 to an H level and the selection signals SG2 and SG3 to an L level. When the command signals SG-A and SG-B designate the receiving electrode 32, the decoder DC1 sets the selection signal SG2 to an H level and the selection signals SG1 and SG3 to an L level. When the command signals SG-A and SG-B designate the receiving electrode 33, the decoder DC1 sets the selection signal SG3 to an H level and the selection signals SG1 and SG2 to an L level.

[0054] When the selection signal SG1 is at H level, the switch SW1 turns on to electrically connect the input terminal 41 and the output terminal 40A. When the selection signal SG1 is at L level, the switch SW1 turns off to electrically disconnect the input terminal 41 and the output terminal 40A.

[0055] When the selection signal SG2 is at H level, the switch SW2 is turned on to electrically connect the input terminal 42 and the output terminal 40A. When the selection signal SG2 is at L level, the switch SW2 is turned off to electrically disconnect the input terminal 42 and the output terminal 40A.

[0056] When the selection signal SG3 is at H level, the switch SW3 turns on to electrically connect the input terminal 43 and the output terminal 40A. When the selection signal SG3 is at L level, the switch SW3 turns off to electrically disconnect the input terminal 43 and the output terminal 40A.

[0057] Next, the procedure for error determination in the detection circuit 63 will be described with reference to Fig. 8. Fig. 8 is a flowchart showing the procedure for error determination in the detection circuit 63. First, in step S21, the detection circuit 63 determines whether or not the stored amount of ink 2 is equal to or greater than a first amount, based on an electrical signal output from the output terminal 40A with the receiving electrode 31 connected. If the stored amount is equal to or greater than the first amount, the process proceeds to step S22, and if the stored amount is not equal to or greater than the first amount, the process determines that the stored amount is less than the first amount, and proceeds to step S24.

[0058] In step S22, the detection circuit 63 determines whether the stored amount of ink 2 is less than the second amount based on the electrical signal output from the output terminal 40A with the receiving electrode 32 connected. If the stored amount is less than the second amount, the process proceeds to step S23, where it is determined that the detection of the stored amount is an error. If the stored amount is equal to or greater than the second amount, the detection circuit 63 ends the process here.

[0059] In step S24, the detection circuit 63 determines whether or not the stored amount of ink 2 is equal to or greater than the second amount, based on the electrical signal output from the output terminal 40A in a state in which the receiving electrode 32 is connected. If the stored amount is equal to or greater than the second amount, the process proceeds to step S25, and if the stored amount is not equal to or greater than the second amount, the detection circuit 63 ends the process here.

[0060] In step S25, the detection circuit 63 determines whether the stored amount of ink 2 is less than the third amount based on the electrical signal output from the output terminal 40A with the receiving electrode 33 connected. If the stored amount is less than the third amount, the process proceeds to step S26 and determines that the detection of the stored amount is an error. If the stored amount is the third amount or more, the detection circuit 63 ends the process here. Note that the process procedure shown in FIG. 8 can be changed arbitrarily. For example, the detection circuit 63 may determine whether the stored amount is the second amount or more after determining whether the stored amount is the third amount or more.

[0061] The storage amount detection device 20A according to the first embodiment includes a selector circuit 36A, which allows switching between electrically connecting to at least one of the receiving electrodes 31-33. The storage amount detection device 20A does not need to provide a determination circuit for each of the receiving electrodes 31-33, which allows the circuit board to be made smaller. The storage amount detection device 20A does not need to perform correction to suppress variations in circuit characteristics that occur when multiple determination circuits are used, which allows the circuit board to be made smaller and the storage amount detection accuracy to be improved.

[0062] In storage amount detection device 20A, filter circuit 37 is provided after selector circuit 36A, so that noise can be removed from the electrical signal output from output terminal 40A. In storage amount detection device 20A, storage amount detection can be performed based on the electrical signal from which noise has been removed, so that the accuracy of detection of storage amount can be improved.

[0063] In liquid ejection device 1A, which is a serial-type inkjet printing device, the carriage 6 reciprocates, causing the liquid level L of the ink 2 stored in storage unit 21A to sway. When the liquid level L sways, the electrostatic capacitance of capacitors 71-73 changes. In storage amount detection device 20A, the filter circuit 37 can remove noise caused by the swaying of the liquid level L, thereby improving the accuracy of detecting the storage amount.

[0064] Next, the connection circuit 80 will be described. As shown in Fig. 2, the storage amount detection device 20A includes a connection circuit 80. The connection circuit 80 connects at least one of the receiving electrodes 31-33 that is not electrically connected to the output terminal 40A to the constant voltage terminal 14. The connection circuit 80 connects the receiving electrodes 31-33 that are not electrically connected to the output terminal 40A, among the receiving electrodes 31-33, to the constant voltage terminal 14. The connection circuit 80 does not connect the receiving electrodes 31-33 that are connected to the output terminal 40A to the constant voltage terminal 14.

[0065] The connection circuit 80 includes switch circuits 81 to 83. The switch circuit 81 is an example of a first switch circuit. The switch circuit 82 is an example of a second switch circuit. The switch circuit 83 is an example of a third switch circuit. The switch circuit 81 switches whether or not the input terminal 41 and the constant voltage terminal 14 are electrically connected. The switch circuit 82 switches whether or not the input terminal 42 and the constant voltage terminal 14 are connected. The switch circuit 83 switches whether or not the input terminal 43 and the constant voltage terminal 14 are connected. The connection circuit 80 electrically connects the receiving electrodes 31 to 33 that are not used to detect the liquid level L of the ink 2 to the constant voltage terminal 14. The connection circuit 80 electrically disconnects the receiving electrodes 31 to 33 that are used to detect the liquid level L from the constant voltage terminal 14.

[0066] A decoder DC2 is electrically connected to the connection circuit 80. The control unit 60 transmits to the decoder DC2 command signals SG-C and SG-D indicating which of the receiving electrodes 31-33 is to be used to measure the liquid level L of the ink 2. Having received the command signals SG-C and SG-D, the decoder DC2 supplies a selection signal SG4 to the switch circuit 81, a selection signal SG5 to the switch circuit 82, and a selection signal SG6 to the switch circuit 83.

[0067] When the command signals SG-C and SG-D indicate the receiving electrode 31, the decoder DC2 sets the selection signal SG4 to an L level and the selection signals SG5 and SG6 to an H level. When the command signals SG-C and SG-D indicate the receiving electrode 32, the decoder DC2 sets the selection signal SG5 to an L level and the selection signals SG4 and SG6 to an H level. When the command signals SG-C and SG-D indicate the receiving electrode 33, the decoder DC2 sets the selection signal SG6 to an L level and the selection signals SG4 and SG5 to an H level.

[0068] When the selection signal SG4 is at H level, the switch circuit 81 turns on to electrically connect the receiving electrode 31 and the constant voltage terminal 14. When the selection signal SG4 is at L level, the switch circuit 81 turns off to electrically disconnect the receiving electrode 31 and the constant voltage terminal 14.

[0069] When the selection signal SG5 is at H level, the switch circuit 82 is turned on to electrically connect the receiving electrode 32 and the constant voltage terminal 14. When the selection signal SG5 is at L level, the switch circuit 82 is turned off to electrically disconnect the receiving electrode 32 and the constant voltage terminal 14.

[0070] When the selection signal SG6 is at H level, the switch circuit 83 turns on to electrically connect the receiving electrode 33 and the constant voltage terminal 14. When the selection signal SG6 is at L level, the switch circuit 83 turns off to electrically disconnect the receiving electrode 33 and the constant voltage terminal 14.

[0071] 9 to 11 are circuit diagrams showing the connection relationship between the receiving electrodes 31-33 that are not connected to the output terminal 40A and the constant voltage terminal 14. The connection circuit 80 switches so that all of the receiving electrodes 31-33 that are not electrically connected to the output terminal 40A are electrically connected to the constant voltage terminal 14. The connection circuit 80 switches whether or not to electrically disconnect only one of the receiving electrodes 31-33 from the constant voltage terminal 14.

[0072] 9, when the receiving electrode 31 is selected to detect the liquid level L of the ink 2, the selector circuit 36A electrically connects the input terminal 41 to the output terminal 40A, and does not connect the input terminal 42 and the input terminal 43 to the output terminal 40A. The switch circuit 82 electrically connects the input terminal 42 to the constant voltage terminal 14, and the switch circuit 83 electrically connects the input terminal 43 to the constant voltage terminal 14. The receiving electrode 31 is not electrically connected to the constant voltage terminal 14. The receiving electrode 31, which is electrically connected to the output terminal 40A, is not shielded by ground potential.

[0073] 10, when the receiving electrode 32 is selected to detect the liquid level L of the ink 2, the selector circuit 36A electrically connects the input terminal 42 to the output terminal 40A, and does not connect the input terminal 41 and the input terminal 43 to the output terminal 40A. The switch circuit 81 electrically connects the input terminal 41 to the constant voltage terminal 14, and the switch circuit 83 electrically connects the input terminal 43 to the constant voltage terminal 14. The receiving electrode 32 is not electrically connected to the constant voltage terminal 14. The receiving electrode 32, which is electrically connected to the output terminal 40A, is not shielded by ground potential.

[0074] 11, when the receiving electrode 33 is selected to detect the liquid level L of the ink 2, the selector circuit 36A electrically connects the input terminal 43 to the output terminal 40A, and does not connect the input terminal 41 and the input terminal 42 to the output terminal 40A. The switch circuit 81 electrically connects the input terminal 41 to the constant voltage terminal 14, and the switch circuit 82 electrically connects the input terminal 42 to the constant voltage terminal 14. The receiving electrode 33 is not electrically connected to the constant voltage terminal 14. The receiving electrode 33, which is electrically connected to the output terminal 40A, is not shielded by ground potential.

[0075] According to such a storage amount detection device 20A, the receiving electrode 30 electrically connected to the output terminal 40A is not electrically connected to the constant voltage terminal 14, and the receiving electrode 30 not electrically connected to the output terminal 40A is electrically connected to the constant voltage terminal 14. This makes it possible to prevent the receiving electrode 30 not used for detecting the liquid level L from being electrically floating. If the receiving electrode 30 not used is floating, when this receiving electrode 30 is electrically connected to the output terminal 40A, there is a risk that residual charges or the like may affect the detection of the liquid level L by the other receiving electrodes 30. In the storage amount detection device 20A, the receiving electrode 30 not used is electrically connected to the constant voltage terminal 14, so that the influence of residual charges or the like can be avoided. As a result, the storage amount detection device 20A improves the detection accuracy of the liquid level L.

[0076] Next, with reference to Figs. 12 to 15, the shield electrodes 91 to 98 covering the transmitting electrode 22 and the receiving electrode 30 will be described. Fig. 12 is a cross-sectional view of the storage section 21A, showing the shield electrodes 91 to 98 covering the transmitting electrode 22 and the receiving electrode 30. Fig. 13 is a cross-sectional view taken along line AA in Fig. 12. Fig. 14 is a view showing the transmitting electrode 22 and the shield electrodes 92, 93. Fig. 15 is a view showing the receiving electrode 30 and the shield electrodes 95 to 98.

[0077] 12, the transmitting electrode 22 is shielded by shield electrodes 91-93. The shield electrodes 91-93 are connected to the ground potential. The receiving electrode 30 is shielded by shield electrodes 94-98. The shield electrodes 94-98 are connected to the ground potential. The shield electrodes 91-98 may be made of the same material as the transmitting electrode 22 and the receiving electrodes 31-33.

[0078] The transmitting electrode 22 has a first surface 22a and a second surface 22b spaced apart in the Y-axis direction. The first surface 22a is the surface on the storage unit 21A side, and the second surface 22b is the surface opposite to the storage unit 21A. The transmitting electrode 22 has a third surface 22c and a fourth surface 22d spaced apart in the Z-axis direction. The third surface 22c is the upper surface, and the fourth surface 22d is the lower surface.

[0079] The shield electrode 91 is disposed so as to cover the second surface 22b of the transmitting electrode 22. The shield electrode 91 and the transmitting electrode 22 are spaced apart in the Y-axis direction. A gap is formed between the shield electrode 91 and the transmitting electrode 22. An insulator may be disposed between the shield electrode 91 and the transmitting electrode 22. The shield electrode 91 has a larger area than the transmitting electrode 22. The shield electrode 91 is disposed so as to cover the entire surface of the second surface 22b of the transmitting electrode 22. The shield electrode 91 may cover a portion of the second surface 22b of the transmitting electrode 22.

[0080] The shield electrode 92 is disposed so as to cover the third surface 22c of the transmitting electrode 22. The shield electrode 92 is disposed above the third surface 22c. An insulator is disposed between the shield electrode 92 and the transmitting electrode 22. A gap may be formed between the shield electrode 92 and the transmitting electrode 22. The shield electrode 91 may be formed so as to cover the entire third surface 22c, or may be formed so as to cover a portion of the third surface 22c.

[0081] The shield electrode 93 is disposed so as to cover the fourth surface 22d of the transmitting electrode 22. The shield electrode 93 is disposed below the fourth surface 22d. An insulator is disposed between the shield electrode 93 and the transmitting electrode 22. A gap may be formed between the shield electrode 93 and the transmitting electrode 22. The shield electrode 93 may be formed so as to cover the entire fourth surface 22d, or may be formed so as to cover a part of the fourth surface 22d. The shield electrode may be disposed on both sides of the transmitting electrode 22 in the X-axis direction.

[0082] The receiving electrode 31 has a first surface 31a and a second surface 31b spaced apart in the Y-axis direction. The first surface 31a is the surface on the storage unit 21A side, and the second surface 31b is the surface opposite the storage unit 21A. The receiving electrode 31 has a third surface 31c and a fourth surface 31d spaced apart in the Z-axis direction. The first surface 31a is the surface on the storage unit 21A side, and the second surface 31b is the surface opposite the storage unit 21A. The third surface 31c is the upper surface, and the fourth surface 31d is the lower surface.

[0083] Similarly, the receiving electrode 32 has a first surface 32a, a second surface 32b, a third surface 32c, and a fourth surface 32d. The first surface 32a and the second surface 32b are spaced apart in the Y-axis direction. The third surface 32c and the fourth surface 32d are spaced apart in the Z-axis direction. The first surface 32a is the surface on the storage unit 21A side, and the second surface 32b is the surface on the opposite side to the storage unit 21A. The third surface 32c is the upper surface, and the fourth surface 32d is the lower surface.

[0084] The receiving electrode 33 has a first surface 33a, a second surface 33b, a third surface 33c, and a fourth surface 33d. The first surface 33a and the second surface 33b are spaced apart in the Y-axis direction. The third surface 33c and the fourth surface 33d are spaced apart in the Z-axis direction. The first surface 33a is the surface on the storage unit 21A side, and the second surface 33b is the surface on the opposite side to the storage unit 21A. The third surface 33c is the upper surface, and the fourth surface 33d is the lower surface.

[0085] The shield electrode 94 is disposed so as to cover the second surface 31b of the receiving electrode 31, the second surface 32b of the receiving electrode 32, and the second surface 33b of the receiving electrode 33. The shield electrode 94 and the receiving electrode 30 are spaced apart in the Y-axis direction. A gap is formed between the shield electrode 91 and the receiving electrode 30. An insulator may be disposed between the shield electrode 94 and the receiving electrode 30. The shield electrode 94 is disposed so as to cover the entire surfaces of the second surface 31b of the receiving electrode 31, the second surface 32b of the receiving electrode 32, and the second surface 33b of the receiving electrode 33. The shield electrode 94 may cover parts of the second surface 33b of the receiving electrode 31, the second surface 32b of the receiving electrode 32, and the second surface 33b of the receiving electrode 33.

[0086] The shield electrode 95 is disposed so as to cover the third surface 31c of the receiving electrode 31. The shield electrode 95 is disposed above the third surface 31c. An insulator is disposed between the shield electrode 95 and the receiving electrode 31. A gap may be formed between the shield electrode 95 and the receiving electrode 31. The shield electrode 95 may be formed so as to cover the entire third surface 31c, or may be formed so as to cover a portion of the third surface 31c.

[0087] The shield electrode 96 is disposed between the receiving electrode 31 and the receiving electrode 32 in the Z-axis direction. The shield electrode 96 is disposed so as to cover the fourth surface 31d of the receiving electrode 31 and the third surface 32c of the receiving electrode 32. An insulator is disposed between the shield electrode 96 and the receiving electrode 31. An insulator is disposed between the shield electrode 96 and the receiving electrode 32. A gap may be formed between the shield electrode 96 and the receiving electrode 31. A gap may be formed between the shield electrode 96 and the receiving electrode 32. The shield electrode 96 may be formed so as to cover the entire surfaces of the fourth surface 31d of the receiving electrode 31 and the third surface 32c of the receiving electrode 32, or may be formed so as to cover parts of the fourth surface 31d and the third surface 32c.

[0088] The shield electrode 97 is disposed between the receiving electrode 32 and the receiving electrode 33 in the Z-axis direction. The shield electrode 97 is disposed so as to cover the fourth surface 32d of the receiving electrode 32 and the third surface 33c of the receiving electrode 33. An insulator is disposed between the shield electrode 97 and the receiving electrode 32. An insulator is disposed between the shield electrode 97 and the receiving electrode 33. A gap may be formed between the shield electrode 97 and the receiving electrode 32. A gap may be formed between the shield electrode 97 and the receiving electrode 33. The shield electrode 97 may be formed so as to cover the entire surfaces of the fourth surface 32d of the receiving electrode 32 and the third surface 33c of the receiving electrode 33, or may be formed so as to cover parts of the fourth surface 32d and the third surface 33c.

[0089] The shield electrode 98 is disposed so as to cover the fourth surface 33d of the receiving electrode 33. The shield electrode 98 is disposed below the fourth surface 33d. An insulator is disposed between the shield electrode 98 and the receiving electrode 33. A gap may be formed between the shield electrode 98 and the receiving electrode 33. The shield electrode 98 may be formed so as to cover the entire fourth surface 33d, or may be formed so as to cover a portion of the fourth surface 33d.

[0090] According to the storage amount detection device 20A, the transmitting electrode 22 and the receiving electrode 30 are covered with the shield electrodes 91 to 98, so that the influence of noise is reduced.

[0091] Next, the influence of noise will be described with reference to Figs. 16 to 18. Fig. 16 is a cross-sectional view of storage unit 21A, showing electric field lines emitted from transmitting electrode 22. Fig. 17 is an enlarged view of receiving electrode 30, showing electric field lines received by receiving electrode 30. Fig. 18 is a cross-sectional view of multiple storage units 21A, 21B, showing electric field lines emitted from multiple transmitting electrodes 22. In each figure, the electric field lines are indicated by dashed lines with arrows.

[0092] 16, electric field lines are emitted from the first surface 22a, the second surface 22b, the third surface 22c, and the fourth surface 22d of the transmitting electrode 22. The electric field lines extending in the Y-axis direction emitted from the first surface 22a can be received by the receiving electrodes 31, 32, and 33. The electric field lines radiated from the third surface 22c and the fourth surface 22d may interfere with surrounding conductors, causing noise. One example of a surrounding conductor that may cause interference is the housing ground.

[0093] 17 shows the receiving electrode 33, and the liquid level L of the ink 2 is located below and close to the fourth surface 33d of the receiving electrode 33. The liquid level L is located outside the liquid level range LV3. If the electric field lines radiated from the third surface 22c and the fourth surface 22d of the transmitting electrode 22 interfere with surrounding conductors, some of the electric field lines that have passed through the ink 2 may bend toward the receiving electrode 33 in the vicinity of the receiving electrode 33 and be received by the fourth surface 33d. As a result, even though the liquid level L is below the liquid level range LV, the output voltage L out The value may not fall below VL [V]. Therefore, the liquid level L may be erroneously detected as being within the liquid level range LV3. There is a risk of such an influence due to noise. The receiving electrodes 31 and 32 may also be influenced by noise in the same manner as the receiving electrode 33.

[0094] As described above, in the storage amount detection device 20A, the second surface 22b, the third surface 22c, and the fourth surface 22d of the transmitting electrode 22 are covered with the shield electrodes 91 to 93. The shield electrodes 91 to 93 suppress the electric field lines emitted from the second surface 22b, the third surface 22c, and the fourth surface 22d, reducing the possibility of interference with surrounding conductors.

[0095] In the storage amount detection device 20A, the second surface 33b, the third surface 33c, and the fourth surface 33d of the receiving electrode 33 are covered by shield electrodes 94, 97, and 98. This prevents the electric field lines around the receiving electrode 33 from being received by the second surface 33b, the third surface 33c, and the fourth surface 33d. As described above, when the liquid level L is below the fourth surface 33d, the electric field lines that have passed through the ink 2 are prevented from being received by the fourth surface 33d. This prevents the output voltage V out As a result, the accuracy of detecting the height position of the liquid level L is improved. The receiving electrodes 31 and 32 are also covered with the shield electrodes 94 to 97, so that the output voltage V out This suppresses a decrease in the detection accuracy of the value of ink 2, and improves the detection accuracy of the height position of the liquid level L. As a result, storage amount detection device 20A can accurately detect the storage amount of ink 2. Furthermore, storage amount detection device 20A prevents electric field lines emitted from other conductors from being received by receiving electrodes 31-33.

[0096] Next, the influence of noise when multiple storage units 21A, 21B are provided will be described with reference to Fig. 18. As shown in Fig. 18, storage unit 21A and storage unit 21B are arranged spaced apart in the Y-axis direction. Transmission electrode 21 of storage unit 21B is arranged next to receiving electrodes 31-33 of storage unit 21A.

[0097] 18, electric field lines are emitted from the first surface 22a, the second surface 22b, the third surface 22c, and the fourth surface 22d of the transmitting electrode 22 of the storage unit 21B. The electric field lines extending in the Y-axis direction emitted from the first surface 22a can be received by the receiving electrodes 31, 32, and 33. Some of the electric field lines emitted from the second surface 22b of the storage unit 21B may be received by the receiving electrode 30 of the storage unit 21A.

[0098] In the storage amount detection device 20A, the second surface 33b, the third surface 33c, and the fourth surface 33d of the receiving electrode 33 are covered by the shield electrodes 94, 97, and 98. This prevents the electric field lines emitted from the transmitting electrode 22 of the adjacent storage unit 21B from being received by the receiving electrode 33 of the storage unit 21A. This reduces the output voltage V out As a result, the accuracy of detecting the height position of the liquid level L is improved. The receiving electrodes 31 and 32 are also covered by the shield electrode, so that the output voltage V out This suppresses a decrease in the detection accuracy of the value of ink L, and improves the detection accuracy of the height position of the liquid level L. As a result, the storage amount detection device 20A can detect the storage amount of ink 2 with high accuracy.

[0099] Next, the switch circuit 13 and the noise detection mode will be described. As shown in Fig. 2, the storage amount detection device 20A includes a switch circuit 13 connected between the AC power supply 12 and the transmitting electrode 22. The storage amount detection device 20A can switch between a noise detection mode for detecting noise and a liquid level detection mode for detecting the storage amount of the ink 2. The storage amount detection device 20A switches the receiving electrodes 31-33 to execute the noise detection mode and the noise detection mode for each of the receiving electrodes 31-33. The storage amount detection device 20A can alternately execute the measurement mode and the noise detection mode.

[0100] The control unit 60 outputs a designation signal that designates the operation mode of the storage amount detection device 20A. When the switch circuit 13 receives the designation signal, it switches OFF, cuts off the connection between the AC power source 12 and the transmitting electrode 22, and executes the noise detection mode. After executing the noise detection mode, the switch circuit 13 switches ON, connects and conducts the AC power source 12 and the transmitting electrode 22, and executes the measurement mode.

[0101] Next, the processing procedure in the storage amount detection device 20A will be described with reference to Fig. 19 to Fig. 21. Fig. 19 is a flowchart showing the processing procedure in the storage amount detection device 20A. Fig. 20 is a flowchart showing the procedure in the noise detection mode. Fig. 21 is a flowchart showing the procedure in the liquid level measurement mode.

[0102] As shown in Fig. 19, the storage amount detection device 20A executes a noise detection mode in step S31. In the noise detection mode, the processes of steps S41 to S48 shown in Fig. 20 are executed. In step S41, the switch circuit 13 is switched OFF to cut off the connection between the AC power supply 12 and the transmitting electrode 22.

[0103] In step S42, the receiving electrodes are selected. The selector circuit 36A connects at least one of the input terminals 41 to 43 to the output terminal 40A, thereby selecting the receiving electrodes 31 to 33. In step S43, the AC power supply 12 outputs a transmission pulse to the S / H 53.

[0104] In step S44, the control unit 60 calculates the output voltage V out The electric signals output from the receiving electrodes 31 to 33 pass through the buffer circuit 51, the BPF 52, the S / H 53, the LPF 54, and the amplifier circuit 55, and are input to the control unit 60. The detection circuit 63 of the control unit 60 detects the output voltage V out Calculate.

[0105] In step S45, the detection circuit 63 detects the output voltage V out is the threshold V thN It is determined whether the threshold value V thN is the output voltage V out This is the threshold value for determining whether or not there is noise in the output voltage V out is the threshold V thN If it is less than 100%, the process proceeds to step S46, where the control unit 60 records that there is no noise and sets the output voltage V out is the threshold V thNIf so, the process proceeds to step S47, where it is recorded that there is noise. In the following step S48, the AC power supply 12 stops outputting the transmission pulse to the S / H 53.

[0106] After executing step S48, the noise detection mode is ended, and step S32 shown in Fig. 19 is executed. In step S32, it is determined whether or not noise has been detected in the noise detection mode. If it is recorded that there is no noise in step S46, the process proceeds to step S33, and the liquid level detection mode is executed, and if it is recorded that there is noise in step S47, the process proceeds to step S34, and a measurement error is recorded, and the liquid level detection mode is not executed. If there is a measurement error, the storage amount detection device 20A can notify the user by displaying it using the notification unit 11.

[0107] In the ink level detection mode in step S33, the processes from step S51 to step S58 shown in Fig. 21 are executed. In step S51, the switch circuit 13 turns the switch ON to connect the AC power supply 12 and the transmitting electrode 22 to establish electrical continuity.

[0108] In step S52, the receiving electrodes 31 to 33 are selected. The selector circuit 36A connects at least one of the input terminals 41 to 43 to the output terminal 40A, thereby selecting the receiving electrodes 31 to 33. In step S53, the AC power supply 12 outputs a transmission pulse to the S / H 53.

[0109] In step S54, the control unit 60 calculates the output voltage V out The electric signals output from the receiving electrodes 31 to 33 pass through the buffer circuit 51, the BPF 52, the S / H 53, the LPF 54, and the amplifier circuit 55, and are input to the control unit 60. The detection circuit 63 of the control unit 60 detects the output voltage V out Measure.

[0110] In step S55, the detection circuit 63 detects the output voltage V out is the threshold V th It is determined whether the threshold value Vth is a judgment threshold value for judging whether the liquid level L of the ink 2 is present at the corresponding height position. out is the threshold V th If it is less than 1 V, the process proceeds to step S56, where the control unit 60 records that the liquid level L is less than the height position of the selected receiving electrode. out is the threshold V th If so, the process proceeds to step S57, where the control unit 60 records that the liquid level L is equal to or higher than the height position of the selected receiving electrode. In the following step S58, the AC power supply 12 stops outputting the transmission pulse to the S / H 53. After executing step S58, the control unit 60 ends the liquid level detection mode.

[0111] Such a storage amount detection device 20A includes a switch circuit 13, and can execute the noise detection mode by cutting off the AC power supply 12 and the transmitting electrode 22. In the storage amount detection device 20A, if a measurement error occurs in the noise detection mode, the liquid level detection mode is not executed, so that erroneous detection due to the influence of noise is prevented. In the storage amount detection device 20A, erroneous detection due to the influence of noise is prevented, so that a decrease in detection accuracy is avoided.

[0112] Since the storage amount detection device 20A includes the selector circuit 36A, it is not necessary to provide a detection circuit for each of the receiving electrodes 31 to 33 in order to execute the noise detection mode, and therefore the circuit board can be made smaller.

[0113] Next, the processing procedure of the storage amount detection device 20A according to the first modified example will be described with reference to Fig. 22. Fig. 22 is a flowchart showing the processing procedure of the storage amount detection device 20A according to the first modified example. The storage amount detection device 20A according to the first modified example differs from the storage amount detection device 20A according to the first embodiment in that the processing procedure shown in Fig. 22 is executed instead of the processing procedure shown in Fig. 19.

[0114] First, in step S61, the control unit 60 of the storage amount detection device 20A resets the NG number count. The NG count number is the number of times that it is recorded that there is noise in the noise detection mode. The NG count number is counted in step S62, which will be described later. After executing step S61, the process proceeds to step S32, where the storage amount detection device 20A executes the noise detection mode shown in FIG. 20.

[0115] After executing the noise detection mode, the process proceeds to step S33. If no noise is detected, the liquid level detection mode is executed in step S34. If noise is detected in the noise detection mode, the process proceeds to step S62, where the number of NGs is counted. The control unit 60 adds "1" to the number of NGs.

[0116] In the next step S63, the control unit 60 judges whether the NG number has reached a limit. The NG number limit can be set arbitrarily. If the NG number has reached the limit, the process proceeds to step S34, where a measurement error is recorded and the liquid level detection mode is not executed.

[0117] If the number of NGs does not reach the limit, the process proceeds to step S64 and sets the waiting time. Next, in step S65, it is determined whether the waiting time has elapsed. If the waiting time has not elapsed, the process of step S65 is repeated, and if the waiting time has elapsed, the process returns to step S31 and executes the noise detection mode.

[0118] In the storage amount detection device 20A according to the first modification, when noise is detected, the device can wait for the standby time to elapse and then execute the noise detection mode again, so even if noise is detected, the device can wait until the noise is no longer detected before executing the liquid level detection mode, thereby improving the reliability of the device.

[0119] Next, a storage amount detection device 20A according to a second modification will be described. Figures 23 to 25 are schematic diagrams of a selector circuit 63A of the storage amount detection device 20A according to the second modification. The storage amount detection device according to the second modification differs from the storage amount detection device 20A according to the first embodiment in that the operation of the selector circuit 36A is different.

[0120] The selector circuit 36A of the storage amount detection device 20A according to the second modification switches whether or not the output terminal 40A is electrically connected to at least two of the input terminals 41 to 43. As shown in FIG. 23, the selector circuit 36A can switch to a state in which the input terminal 41 and the output terminal 40A are electrically connected, and the input terminal 42 and the output terminal 40A are electrically connected. As shown in FIG. 24, the selector circuit 36A can switch to a state in which the input terminal 42 and the output terminal 40A are electrically connected, and the input terminal 43 and the output terminal 40A are electrically connected. As shown in FIG. 25, the selector circuit 36A can switch to a state in which the input terminal 41 and the output terminal 40A are electrically connected, and the input terminal 42 and the output terminal 40A are electrically connected.

[0121] In the storage amount detection device 20A of the second modification, when the input terminal 41 and the input terminal 42 are connected to the output terminal 40A, a capacitor 74 is formed with the receiving electrodes 31 and 32 as receiving electrodes. th If it exceeds this range, the detection circuit 63 determines that the liquid level L is in the liquid level range LV1 or LV2.

[0122] In this storage amount detection device 20A, when the input terminal 42 and the input terminal 43 are connected to the output terminal 40A, a capacitor 75 is formed with the receiving electrodes 32 and 33 as receiving electrodes. th If it exceeds this range, the detection circuit 63 determines that the liquid level L is in the liquid level range LV2 or LV3.

[0123] In this storage amount detection device 20A, when the input terminal 41 and the input terminal 43 are connected to the output terminal 40A, a capacitor 76 is formed with the receiving electrodes 31 and 33 as receiving electrodes. th If it exceeds this range, the detection circuit 63 determines that the liquid level L is in the liquid level range LV1 or LV3.

[0124] The storage amount detection device 20A according to the second modified example also exhibits the same effects as those of the storage amount detection device 20A according to the first embodiment.

[0125] Next, a liquid ejection device 1B according to a second embodiment will be described with reference to Figures 26 and 27. Note that in the description of the second embodiment, descriptions similar to those of the previous embodiment will be omitted.

[0126] FIG. 26 is a schematic diagram of a liquid ejection device 1B according to a second embodiment. FIG. 27 is a schematic diagram of a storage amount detection device 20B according to a second embodiment. The liquid ejection device 1B is equipped with a storage amount detection device 20B. The liquid ejection device 1B is a serial type inkjet printer. The liquid ejection device 1B is equipped with a carriage 6 that can move back and forth. The carriage 6 stores four ink cartridges 15A to 15D that correspond one-to-one to the four colors of ink. The carriage 6 is provided with an ejection unit 4 for each of the four ink cartridges 15A to 15D.

[0127] Ink cartridge 15A has a storage portion 21A that stores yellow ink 2. Ink cartridge 15B has a storage portion 21B that stores magenta ink 2. Ink cartridge 15C has a storage portion 21C that stores cyan ink 2. Ink cartridge 15D has a storage portion 21D that stores black ink 2.

[0128] The storage amount detection device 20B shown in FIG. 27 differs from the storage amount detection device 20A according to the first embodiment in that it includes a plurality of storage units 21A-21D and a storage unit selection circuit 45. The storage units 21A-21D have the same configuration as the storage unit 21A according to the first embodiment. Selector circuits 36A-36D are provided for the four storage units 21A-21D, respectively. The selector circuits 36A-36D have output terminals 40A-40D, respectively. The selector circuits 36B-36D have the same configuration as the selector circuit 36A according to the previous embodiment, and the output terminals 40B-40D have the same configuration as the output terminal 40A according to the previous embodiment.

[0129] The storage section selection circuit 45 includes a plurality of switch circuits 46 A to 46 D. An output terminal 47 of the storage section selection circuit 45 is electrically connected to a buffer circuit 51 in the subsequent stage.

[0130] The storage unit selection circuit 45 switches whether the output terminal 47 is connected to one of the multiple selector circuits 36A to 36D. The switch circuit 46A switches whether the selector circuit 36A and the output terminal 47 are electrically connected or not. The switch circuit 46A switches whether the selector circuit 36A and the output terminal 47 are electrically connected or not. The switch circuit 46B switches whether the selector circuit 36B and the output terminal 47 are electrically connected or not. The switch circuit 46C switches whether the selector circuit 36C and the output terminal 47 are electrically connected or not. The switch circuit 46D switches whether the selector circuit 36D and the output terminal 47 are electrically connected or not.

[0131] The control unit 60 outputs a command signal indicating ON / OFF of the switch circuits 46A-46D. The command signal is input to the storage unit selection circuit 45. The storage unit selection circuit 45 switches the switch circuits 46A-46D based on the storage unit selection signal. When detecting the liquid level L of the ink 2 stored in the storage unit 21A, the storage unit selection circuit 45 switches ON the switch circuit 46A to electrically connect the selector circuit 36A to the output terminal 47. In this case, the storage unit selection circuit 45 switches OFF the remaining selector circuits 36B-38D to electrically disconnect the selector circuits 36B-36D from the output terminal 47. As a result, of the selector circuits 36A-36D, only the selector circuit 36A is electrically connected to the output terminal 47.

[0132] Similarly, when detecting the liquid level L of the ink 2 stored in the storage unit 21B, the storage unit selection circuit 45 electrically connects the selector circuit 36B to the output terminal 47 and electrically disconnects the selector circuits 36A, 36C, and 36D from the output terminal 47.

[0133] When detecting the liquid level L of the ink 2 stored in the storage unit 21C, the storage unit selection circuit 45 electrically connects the selector circuit 36C to the output terminal 47 and electrically disconnects the selector circuits 36A, 36B, and 36D from the output terminal 47.

[0134] When detecting the liquid level L of the ink 2 stored in the storage unit 21D, the storage unit selection circuit 45 electrically connects the selector circuit 36D to the output terminal 47 and electrically disconnects the selector circuits 36A, 36B, and 36C from the output terminal 47.

[0135] The storage amount detection device 20B according to the second embodiment includes a storage unit selection circuit 45, and can switch whether or not the output terminal 47 is connected to one of the multiple selector circuits 36A-36D. Since the storage amount detection device 20B does not need to provide a detection circuit for each of the multiple storage units 21A-21D, the circuit board can be made smaller. Since the storage amount detection device 20B does not need to perform correction to suppress variations in circuit characteristics that occur when multiple detection circuits are used, the circuit board can be made smaller and the storage amount detection accuracy can be improved.

[0136] Next, a storage amount detection device 20C according to a third modification will be described with reference to Figs. 28 and 29. The storage amount detection device according to the third modification differs from the storage amount detection device 20A according to the first embodiment in that the receiving electrode 30 has four receiving electrodes 31-34. The selector circuit 36A includes an input terminal 44 electrically connected to the receiving electrode 34. The receiving electrode 34 is disposed at a lower height position than the receiving electrodes 31-33.

[0137] 28, the selector circuit 36A of the storage amount detection device 20C switches whether or not at least one of the input terminals 41-44 is electrically connected to the output terminal 40A. When the receiving electrode 34 is selected to detect the liquid level L, the selector circuit 36A electrically connects the output terminal 40A to the receiving electrode 34 and electrically disconnects the output terminal 40A from the receiving electrodes 31-33.

[0138] The detection circuit 63 determines whether or not the stored amount of ink 2 is equal to or greater than a fourth amount, based on the output from the output terminal 40A in a state in which the receiving electrode 34 is connected. The fourth amount is less than the third amount.

[0139] The selector circuit 36A of the storage amount detection device 20C can switch whether or not at least two of the input terminals 41-44 are electrically connected to the output terminal 40A. The selector circuit 36A can electrically connect the input terminals 43, 44 to the output terminal 40A, and can electrically disconnect the input terminals 41, 43 from the output terminal 40A.

[0140] As shown in Fig. 29, the selector circuit 36A of the storage amount detection device 20C switches whether or not at least two of the input terminals 41-44 are electrically connected to the output terminal 40A. The selector circuit 36A electrically connects the input terminals 41-43 to the output terminal 40A, and electrically disconnects the input terminal 44 from the output terminal 40A. The selector circuit 36A electrically disconnects only one of the input terminals 41-44 from the output terminal 40A.

[0141] The selector circuit 36A may electrically connect two of the multiple input terminals 41-44 to the output terminal 40A and electrically disconnect the remaining two input terminals 41-44 from the output terminal 40A. For example, the selector circuit 36A can electrically connect the input terminals 43, 44 to the output terminal 40A and electrically disconnect the remaining input terminals 41, 42 from the output terminal 40A.

[0142] Next, with reference to Fig. 30, an error determination in the storage amount detection device 20C of the third modified example will be described. Fig. 30 is a flowchart showing the procedure of error determination in the detection circuit 63 of the storage amount detection device 20C. In the storage amount detection device 20C, the liquid level L is detected using a receiving electrode arranged at a low position, and the liquid level L is detected using receiving electrodes arranged at successively higher positions. In the storage amount detection device 20C, the liquid level L is detected in the order of receiving electrode 34, receiving electrode 33, receiving electrode 32, and receiving electrode 31.

[0143] 30, first, in step S71, detection circuit 63 determines whether the stored amount of ink 2 is a fourth amount or more based on the output from output terminal 40A with receiving electrode 34 electrically connected. If the stored amount is the fourth amount or more, the process proceeds to step S42, and if the stored amount is not the fourth amount or more, the process determines that the stored amount is less than the fourth amount and proceeds to step S74.

[0144] In step S72, the detection circuit 63 determines whether or not the stored amount of ink 2 is less than the third amount, based on the electrical signal output from the output terminal 40A with the receiving electrodes 31-33 connected. With the receiving electrodes 31-33 electrically connected to the output terminal 40A, the receiving electrode 34 is electrically disconnected from the output terminal 40A. If the liquid level L is detected by the receiving electrodes 31-33, the detection circuit 63 determines that the stored amount is equal to or greater than the third amount. If the liquid level L is not detected by the receiving electrodes 31-33, the detection circuit 63 determines that the stored amount is less than the third amount.

[0145] If the storage amount is less than the third amount, the detection circuit 63 proceeds to step S73 and determines that the detection of the storage amount is an error. The process proceeds to step S73 when the storage amount is determined to be equal to or greater than the fourth amount and is less than the third amount, and therefore the detection of the storage amount is determined to be an error. If the storage amount is equal to or greater than the third amount, the detection circuit 63 ends the process here.

[0146] In step S74, the detection circuit 63 determines whether the stored amount of ink 2 is equal to or greater than a third amount, based on the electrical signal output from the output terminal 40A with the receiving electrode 33 connected. With the receiving electrode 33 electrically connected to the output terminal 40A, the receiving electrodes 31, 32, and 34 are electrically disconnected from the output terminal 40A. If the stored amount is equal to or greater than the third amount, the detection circuit 63 proceeds to step S75, and if the stored amount is not equal to or greater than the third amount, the detection circuit 63 proceeds to step S77.

[0147] In step S75, the detection circuit 63 determines whether the stored amount of ink 2 is less than the second amount based on the electrical signal output from the output terminal 40A with the receiving electrodes 31, 32 connected. With the receiving electrodes 31, 32 electrically connected to the output terminal 40A, the receiving electrodes 33, 34 are electrically disconnected from the output terminal 40A. If the liquid level L is detected by the receiving electrodes 31, 32, the detection circuit 63 determines that the stored amount is equal to or greater than the second amount. If the liquid level L is not detected by the receiving electrodes 31, 32, the detection circuit 63 determines that the stored amount is less than the second amount.

[0148] If the storage amount is less than the second amount, the detection circuit 63 proceeds to step S76 and determines that the detection of the storage amount is an error. The process proceeds to step S76 when the storage amount is determined to be equal to or greater than the third amount and is less than the second amount, and therefore the detection of the storage amount is determined to be an error. If the storage amount is equal to or greater than the second amount, the detection circuit 63 ends the process here.

[0149] In step S77, the detection circuit 63 determines whether the stored amount of ink 2 is equal to or greater than the second amount, based on the electrical signal output from the output terminal 40A with the receiving electrode 32 connected. With the receiving electrode 32 electrically connected to the output terminal 40A, the receiving electrodes 32, 32, 34 are electrically disconnected from the output terminal 40A. If the stored amount is equal to or greater than the second amount, the process proceeds to step S78, and if the stored amount is not equal to or greater than the second amount, the detection circuit 63 ends the process here.

[0150] In step S75, the detection circuit 63 determines whether or not the stored amount of ink 2 is less than the first amount, based on the electrical signal output from the output terminal 40A with the receiving electrode 31 connected. With the receiving electrode 31 electrically connected to the output terminal 40A, the receiving electrodes 32-34 are electrically disconnected from the output terminal 40A. If the liquid level L is detected by the receiving electrode 31, the detection circuit 63 determines that the stored amount is equal to or greater than the first amount. If the liquid level L is not detected by the receiving electrode 31, the detection circuit 63 determines that the stored amount is less than the first amount.

[0151] If the storage amount is less than the first amount, the detection circuit 63 proceeds to step S79 and determines that the detection result of the storage amount is an error. If the storage amount is determined to be equal to or greater than the second amount and less than the first amount, the detection circuit 63 determines that the detection result of the storage amount is an error. If the storage amount is equal to or greater than the first amount, the detection circuit 63 ends the process here.

[0152] According to the storage amount detection device 20C of the third modified example, the selector circuit 36A electrically connects the multiple receiving electrodes 31-34 to the output terminal 40A, and the liquid level L can be detected. Since the multiple receiving electrodes 31-34 are connected to detect the liquid level L and it is determined whether or not the detection result of the storage amount is an error, it is not necessary to measure the liquid level L for each receiving electrode 31-34. Therefore, the error determination can be performed quickly, and an increase in the processing load on the detection circuit 63 is suppressed.

[0153] Next, referring to FIG. 31, the output voltage V out The relationship between the output voltage V out 31 is a table showing the relationship between the output voltage V out is the threshold V th "L" indicates that the output voltage is greater than or equal to Vout is the threshold V th "H / L" indicates that it is "H" or "L".

[0154] In case 1, the output voltage V of the receiving electrodes 31 to 33 out are all "H", and the detection circuit 63 determines that the detection result of the storage amount is normal. In case 1, the detection circuit 63 determines that the storage amount is equal to or greater than the first amount as the detection result of the storage amount. In case 2, the output voltage V out is “H”, the receiving electrode 32 is “L”, and the output voltage V out Regardless of the above, the detection circuit 63 determines that the detection result of the storage amount is an error. out is “H”, the receiving electrode 32 is “H”, and the output voltage V out is "L", and the detection circuit 63 determines that the detection result of the storage amount is an error.

[0155] In case 4, the output voltage V of the receiving electrode 31 out is "L", and the output voltage V out is "H / L", and the output voltage V out In case 4, the output voltage V of the receiving electrode 32 is “H”, and the detection circuit 63 determines that the detection result of the storage amount is normal. out In case 4, when the output voltage V of the receiving electrode 32 is “H”, the detection circuit 63 determines that the storage amount is equal to or greater than the second amount as the detection result of the storage amount. out In case 5, when the output voltage V of the receiving electrode 31 is “L”, the detection circuit 63 determines that the storage amount is equal to or greater than the third amount as the detection result of the storage amount. out is "L", and the output voltage V out In case 6, the output voltage V of the receiving electrode 31 is “H” and the output voltage V of the receiving electrode 31 is “L”. out is "L", and the output voltage V out is "L", and the output voltage V outis "L", and the detection circuit 63 determines that the detection result of the storage amount is normal. In case 6, the detection circuit 63 determines that the detection result of the storage amount is that the storage amount is less than the third amount.

[0156] Next, referring to FIG. 32, the output voltage V out The relationship between the output voltage V out 32 is a table showing the relationship between the detection result and the storage amount detection device 20C including the four receiving electrodes 31 to 34 shown in FIGS. 28 and 29 indicates whether the detection result is normal or erroneous.

[0157] In Fig. 32, a case where an error determination is performed by electrically connecting two or more of the four receiving electrodes 31-34 to the output terminal 40A will be described. In Fig. 32, a part of a case where two or more receiving electrodes 31-34 are connected to the output terminal 40A will be described. In the case shown in Fig. 32, as shown in Fig. 30, measurement is performed first using the receiving electrode 34 arranged at a low position, and then measurements are performed using the receiving electrodes 33, 32, and 31 arranged at higher positions.

[0158] In cases 1 to 3, the storage amount detection device 20C performs measurement using the receiving electrode 34 first, and then performs measurement using the receiving electrodes 31 to 33. In these cases 1 to 3, the detection circuit 63 performs error determination based on the output in a state in which the receiving electrodes 31 to 33 are simultaneously connected to the output terminal 40A. In case 7, the output voltage V out is "L", and the output voltage V out is "L", and the detection circuit 63 determines that the detection result of the storage amount is normal. In case 7, the detection circuit 63 determines that the storage amount is less than the fourth amount as the detection result of the storage amount. In case 2, the output voltage V out is "L", and the output voltage V out In case 3, the output voltage V of the receiving electrode 34 is “H”, and the detection circuit 63 determines that the detection result of the storage amount is an error. outis "H", and the output voltage V out is "L", and the detection circuit 63 determines that the detection result of the storage amount is normal. In case 3, the detection circuit 63 determines that the detection result of the storage amount is the fourth amount or more.

[0159] In cases 4 to 6, storage amount detection device 20C first performs measurement using receiving electrodes 33, 34, and then performs measurement using receiving electrodes 31, 32. In the measurement using receiving electrodes 33, 34, detection circuit 63 performs error determination based on the output when receiving electrodes 33, 34 are simultaneously connected to output terminal 40A. In the measurement using receiving electrodes 31, 32, detection circuit 63 performs error determination based on the output when receiving electrodes 31, 32 are simultaneously connected to output terminal 40A.

[0160] In case 4, the output voltage V of the receiving electrodes 33 and 34 out is "L", and the output voltage V out is "L", and the detection circuit 63 determines that the detection result of the storage amount is normal. In case 4, the detection circuit 63 determines that the storage amount is less than the fourth amount as the detection result of the storage amount. In case 5, the output voltage V out is "L", and the output voltage V out In case 6, the output voltage V out is "H", and the output voltage V out is "L", and the detection circuit 63 determines that the detection result of the storage amount is normal. In case 6, the detection circuit 63 determines that the detection result of the storage amount is the third amount or more, or the fourth amount or more.

[0161] In cases 7 to 9, storage amount detection device 20C first performs measurement using receiving electrodes 32 to 34, and then performs measurement using receiving electrode 31. In the measurement using receiving electrodes 32 to 34, detection circuit 63 performs error determination based on the output when receiving electrodes 32 to 34 are simultaneously connected to output terminal 40A.

[0162] In case 7, the output voltage V of the receiving electrodes 32 to 34 out is "L", and the output voltage V out In case 8, the output voltage V of the receiving electrodes 32 to 34 is “H”, and the detection circuit 63 determines that the detection result of the storage amount is an error. out is "L", and the output voltage V out is "L", and the detection circuit 63 determines that the detection result of the storage amount is normal. In case 8, the detection circuit 63 determines that the storage amount is less than the fourth amount as the detection result of the storage amount. In case 9, the output voltage V out is "H", and the output voltage V out In case 9, the output voltage V of the receiving electrode 31 is “H / L”, and the detection circuit 63 determines that the detection result of the storage amount is normal. out In case 9, when the output voltage V out is "L", the detection circuit 63 determines that the storage amount is equal to or less than the second amount as the detection result of the storage amount.

[0163] According to the storage amount detection device 20C, the output voltage V out can be used to determine whether or not the detection result of the storage amount is an error. This eliminates the need to perform measurement by switching the receiving electrodes 31 to 34 individually. According to the storage amount detection device 20C, an increase in the processing load of the control unit 60 when performing error determination is suppressed.

[0164] It should be noted that the above-described embodiment merely illustrates a typical form of the present invention, and the present invention is not limited to the above-described embodiment, and various modifications and additions are possible without departing from the gist of the present invention.

[0165] In the above-described embodiment, the storage amount detection device 20A is configured to have three receiving electrodes 31 to 33, but the storage amount detection device 20A may be configured to have two receiving electrodes 30, or may be configured to have four or more receiving electrodes 30.

[0166] In the above embodiment, the receiving electrodes 31 to 33 are arranged at different height positions, but the receiving electrodes 31 to 33 may be arranged at the same height position.

[0167] In the above embodiment, ink 2 is exemplified as the object stored in storage units 21A to 21D, but the object stored in storage units 21A to 21D may be another liquid, a solid, or a gas.

[0168] In the above embodiment, the liquid ejection devices 1A and 1B in which the ejection unit 4 and the storage units 21A to 21D are mounted on the carriage 6 have been described, but the liquid ejection devices 1A and 1B are not limited to this and may be ones in which the ejection unit 4 and the storage unit 21A are not mounted on the carriage 6. Furthermore, the liquid ejection devices 1A and 1B are not limited to serial type inkjet printers and may be other printing devices.

[0169] In the above-described embodiment, the storage units 21A-21D are exemplified as ink cartridges for the liquid ejection devices 1A and 1B, but the storage units 21A-21D may be ink tanks that store the ink 2 used in other printing devices. The storage units 21A-21D may be mounted on an ink server that supplies the ink 2 to the printing device. [Explanation of symbols]

[0170] Reference Signs List 1A, 1B...Liquid ejection device, 2...Ink, 4...Ejection section, 6...Carriage, 14...Constant voltage terminal, 20A, 20B, 20C...Storage amount detection device, 21A to 21D...Storage section, 22...Transmitting electrode, 28a...Outer surface of side plate (first surface of storage section), 29a...Outer surface of side plate (second surface of storage section), 30...Receiving electrode, 31...Receiving electrode (first receiving electrode), 32...Receiving electrode (second receiving electrode), 33...Receiving electrode (third receiving electrode), 34...Receiving electrode, 36A to 36D...Selector circuit, 37...Filter circuit, 38...A / D converter, 40A ~40D...output terminal, 41...input terminal (first input terminal), 42...input terminal (second input terminal), 43...input terminal (third input terminal), 52...BPF (band pass filter circuit), 53...S / H, 54...LPF (low pass filter circuit), 55...amplification circuit, 63...detection circuit, 80...connection circuit, 81...switch circuit (first switch circuit), 82...switch circuit (second switch circuit), 83...switch circuit (third switch circuit), L...liquid level, X...X-axis direction, Y...Y-axis direction (first direction), Z...Z-axis direction (height direction).

Claims

1. a storage section having a first surface and a second surface spaced apart from the first surface in a first direction, the storage section being capable of storing an object between the first surface and the second surface; A transmitting electrode provided on the first surface; a first receiving electrode provided on the second surface; a second receiving electrode provided on the second surface; An output terminal; a selector circuit that switches whether or not the output terminal is electrically connected to at least one of the first receiving electrode and the second receiving electrode; a detection circuit for detecting an amount of the object stored in the storage unit based on an output from the output terminal; A storage amount detection device comprising: The detection circuit includes: determining whether or not a storage amount of the object is equal to or greater than a first amount based on an output from the output terminal in a state in which the first receiving electrode is connected; Based on an output from the output terminal in a state in which the second receiving electrode is connected, it is determined whether or not the stored amount of the object is equal to or greater than a second amount that is smaller than the first amount. Storage volume detection device.

2. The detection circuit includes: a determination result based on an output from the output terminal in a state in which the selector circuit electrically connects the output terminal and the first receiving electrode; a determination result based on an output from the output terminal in a state in which the selector circuit electrically connects the output terminal and the second receiving electrode; The amount of the object stored in the storage unit is detected based on the The storage amount detection device according to claim 1 .

3. It is determined that the storage amount of the object is equal to or greater than the first amount based on an output from the output terminal in a state in which the first receiving electrode is connected, and When it is determined that the storage amount of the object is less than the second amount based on an output from the output terminal in a state in which the second receiving electrode is connected, The detection circuit determines that the detection of the stored amount is an error. The storage amount detection device according to claim 2.

4. a third receiving electrode provided on the second surface; the selector circuit switches whether or not the output terminal is electrically connected to at least one of the first receiving electrode, the second receiving electrode, and the third receiving electrode; The detection circuit determines whether the stored amount of the object is equal to or greater than a third amount that is less than the second amount, based on an output from the output terminal in a state in which the third receiving electrode is connected. The storage amount detection device according to claim 2 or 3.

5. It is determined that the stored amount of the object is less than the first amount based on an output from the output terminal in a state in which the first receiving electrode is connected, and It is determined that the storage amount of the object is equal to or greater than the second amount based on an output from the output terminal in a state in which the second receiving electrode is connected, and When it is determined that the storage amount of the object is less than the third amount based on an output from the output terminal in a state in which the third receiving electrode is connected, The detection circuit determines that the detection of the stored amount is an error. The storage amount detection device according to claim 4.

6. The selector circuit switches whether or not the output terminal is electrically connected to at least two of the first receiving electrode, the second receiving electrode, and the third receiving electrode. The storage amount detection device according to claim 4 or 5.

7. The storage amount detection device according to any one of claims 1 to 6, wherein the object is a liquid.

8. A storage amount detection device according to claim 7, a discharge unit that discharges the liquid; A liquid ejection device comprising:

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