Patent Publication Number: US-11654689-B2

Title: Liquid discharge device

Description:
The present application is based on, and claims priority from JP Application Serial Number 2020-183187, filed Oct. 30, 2020, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a liquid discharge device. 
     2. Related Art 
     A residual quantity sensing sensor that detects a residual quantity of contents of a container is known (for example, JP-A-2008-230227). The residual quantity sensing sensor includes a detection electrode disposed to face the container and a guard electrode disposed to face the detection electrode to be coupled to a reference potential, in which the residual quantity of the contents of the container is detected based on electrostatic capacitance measured by the detection electrode. 
     In a technique described in JP-A-2008-230227, when a liquid level of the contents of the container fluctuates, electrostatic capacitance changes, so that there is a problem in that the liquid level cannot be detected accurately. 
     SUMMARY 
     According to an aspect of the present disclosure, there is provided a liquid discharge device including a discharge section that discharges a liquid, a storage section that includes a first surface and a second surface separated from the first surface in a first direction, and is configured to store the liquid between the first surface and the second surface, a transmission electrode that is provided on the first surface, a reception electrode that is provided on the second surface, a filter circuit that removes a predetermined frequency component from an electric signal supplied from the reception electrode, and a detection circuit that detects a storage amount of the liquid stored in the storage section based on an output from the filter circuit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram of a liquid discharge device according to a first embodiment. 
         FIG.  2    is a schematic diagram of a storage amount detection device according to the first embodiment. 
         FIG.  3    is a cross-sectional diagram of a storage section. 
         FIG.  4    is a graph showing a relationship between a liquid level and an output voltage from a capacitor. 
         FIG.  5    is a circuit diagram of the storage amount detection device. 
         FIG.  6    is a block diagram of the storage amount detection device. 
         FIG.  7    is a flowchart showing an operation of a selector circuit. 
         FIG.  8    is a circuit diagram including the selector circuit. 
         FIG.  9    is a circuit diagram showing a coupling relationship between a reception electrode, which is not coupled to an output terminal, and a constant voltage terminal. 
         FIG.  10    is a circuit diagram showing the coupling relationship between the reception electrode, which is not coupled to the output terminal, and the constant voltage terminal. 
         FIG.  11    is a circuit diagram showing the coupling relationship between the reception electrode, which is not coupled to the output terminal, and the constant voltage terminal. 
         FIG.  12    is a cross-sectional diagram showing the storage section provided with a shield electrode. 
         FIG.  13    is a cross-sectional diagram taken along a line XIII-XIII in  FIG.  12   . 
         FIG.  14    is a diagram showing a transmission electrode and the shield electrode. 
         FIG.  15    is a diagram showing the reception electrode and the shield electrode. 
         FIG.  16    is a cross-sectional diagram of the storage section, that is, a diagram showing lines of electric force emitted from the transmission electrode. 
         FIG.  17    is a diagram showing the lines of electric force received by the reception electrode. 
         FIG.  18    is a cross-sectional diagram of a plurality of storage sections, that is, a diagram showing lines of electric force emitted from a plurality of transmission electrodes. 
         FIG.  19    is a flowchart showing a processing procedure of the storage amount detection device. 
         FIG.  20    is a flowchart showing a procedure in a noise detection mode. 
         FIG.  21    is a flowchart showing a procedure in a liquid level measurement mode. 
         FIG.  22    is a flowchart showing a processing procedure of the storage amount detection device according to a first modification example. 
         FIG.  23    is a circuit diagram showing an operation of a selector circuit according to a second modification example. 
         FIG.  24    is a circuit diagram showing the operation of the selector circuit according to the second modification example. 
         FIG.  25    is a circuit diagram showing the operation of the selector circuit according to the second modification example. 
         FIG.  26    is a schematic diagram of a liquid discharge device according to a second embodiment. 
         FIG.  27    is a schematic diagram of a storage amount detection device according to the second embodiment. 
         FIG.  28    is a circuit diagram showing an operation of a selector circuit according to a third modification example. 
         FIG.  29    is a circuit diagram showing the operation of the selector circuit according to the third modification example. 
         FIG.  30    is a flowchart showing an error determination procedure in a detection circuit according to the third modification example. 
         FIG.  31    is a table showing a relationship between an output voltage and a detection result. 
         FIG.  32    is a table showing the relationship between the output voltage and the detection result. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Hereinafter, embodiments for carrying out the present disclosure will be described with reference to the accompanying drawings. However, in each drawing, a dimension and a scale of each section are appropriately different from actual ones. Further, since the embodiments which will be described below are suitable specific examples of the present disclosure, various technically preferable limitations are attached. However, the scope of the present disclosure is not limited to the embodiments unless the following description dos not particularly limit the present disclosure. 
       FIG.  1    is a schematic diagram of a liquid discharge device  1 A including a storage amount detection device  20 A. The liquid discharge device  1 A is an ink jet printer that discharges 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  20 A detects the storage amount of the ink  2  stored in the storage section  21 A. 
     Print data indicating an image to be formed by the liquid discharge device  1 A is supplied to the liquid discharge device  1 A from a host computer such as a personal computer or a digital camera. The liquid discharge device  1 A executes a printing process of forming the image, which is indicated by the print data supplied from the host computer, on the recording paper P. 
     The liquid discharge device  1 A is a serial printer. Specifically, when executing the printing process, the liquid discharge device  1 A transports the recording paper P in a sub scanning direction and discharges the ink  2  from the discharge section  4  while reciprocating a head unit  3  toward a main scanning direction that intersects the sub scanning direction, thereby forming dots corresponding to the print data on the recording paper P. 
     In  FIG.  1   , an X-axis direction, a Y-axis direction, and a Z-axis direction are shown. 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 a height direction. The Y-axis direction is an example of a first direction that intersects the height direction. 
     The liquid discharge device  1 A includes a housing  5 , a carriage  6 , and a transport unit  7 . When the printing process is executed, the transport unit  7  reciprocates the carriage  6  in the Y-axis direction and transports the recording paper P in the X-axis direction to change a relative position of the recording paper P with respect to the head unit  3 , so that the ink  2  can 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. 
     The liquid discharge device  1 A includes a medium storage section  10  that stores the recording paper P. The recording paper P is supplied from the medium storage section  10  to the medium transport mechanism  9  and is transported to the vicinity of the head unit  3 . 
     The liquid discharge device  1 A includes a notification section  11 . The notification section  11  includes a liquid crystal display device. The notification section  11  may be configured to provide a notification by voice, may be configured to provide a notification by vibration, or may be configured to provide a notification by a blinking pattern of a lamp. A screen of a personal computer or a device, such as a smartphone, having a communication function may function as the notification section. The notification section  11  displays a detection result by a detection circuit  63  which will be described later. The notification section  11  can display other information. 
       FIG.  2    is a schematic diagram of the storage amount detection device  20 A.  FIG.  3    is a cross-sectional diagram of the storage section  21 A. As shown in  FIG.  2   , the storage amount detection device  20 A includes a storage section  21 A, a transmission electrode  22 , a reception electrode  30 , a detection section  50 , and a control section  60 . The control section  60  serves as the control section for each section of the liquid discharge device  1 A. 
     As shown in  FIG.  3   , the storage section  21 A includes 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 separated from each other in the Y-axis direction. The cylindrical body  25  includes a plurality of side plates (not shown) that are separated from each other in the X-axis direction. The bottom plate  26  is disposed 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 . A space inside the cylindrical body  25  is a space that accommodates the liquid. 
     A constituent material of the storage section  21 A is not particularly limited as long as the constituent material does not transmit the ink  2  and is composed of a dielectric, and, for example, various resin materials, such as polyolefin, polycarbonate, polyester, and various glass materials can be used. Further, the storage section  21 A may be hard or soft, and a part thereof may be hard and a remaining part may be soft. 
     An outlet (not shown) is formed on the bottom plate  26 . The liquid stored in the storage section  21 A is discharged through the outlet. The outlet communicates with a discharge section  4  of the head unit  3 . When the ink  2  is discharged from the head unit  3 , the storage amount of the ink  2  stored in the storage section  21 A decreases, and a liquid level L decreases. The storage amount detection device  20 A can detect the liquid level L of the ink  2  to grasp a residual quantity of the ink  2 . The notification section  11  provides a notification to a user by displaying the residual quantity of the ink  2 , thereby preventing the ink  2  from running out at an undesired timing. 
     A transmission electrode  22  is provided on an outer surface  28   a  of the side plate  28  of the storage section  21 A. The outer surface  28   a  of the side plate  28  is an example of a first surface of the storage section  21 A. The reception electrode  30  is provided on an outer surface  29   a  of the side plate  29  of the storage section  21 A. The outer surface  29   a  of the side plate  29  is an example of a second surface of the storage section  21 A. The first surface and the second surface of the storage section may be separated in the X-axis direction, may be separated in the Y-axis direction, or may be separated in the other directions. 
     The reception electrode  30  includes reception electrodes  31  to  33 . The reception electrode  31  is an example of a first reception electrode. The reception electrode  32  is an example of a second reception electrode. The reception electrode  33  is an example of a third reception electrode. 
     The transmission electrode  22  and the reception electrodes  31  to  33  are made of a conductive material, for example, a metal material such as gold, silver, copper, aluminum, iron, nickel, cobalt, or an alloy containing the materials. The transmission electrode  22  and the reception electrodes  31  to  33  may be formed directly on the outer surfaces of the side plates  28  and  29  by, for example, plating, vapor deposition, printing, or the like, may be attached to the outer surfaces of the side plates  28  and  29  via an adhesive layer (not shown), or may be supported by a support member (not shown) in contact or non-contact with the side plates  28  and  29 . 
     The reception electrodes  31  to  33  are disposed at positions that overlap the transmission electrode  22  when viewed from the X-axis direction. The reception electrodes  31  to  33  are disposed at different positions from each other in the height direction. The reception electrode  31  is disposed at a position higher than the positions of the reception electrodes  32  and  33 , and the reception electrode  32  is disposed at a position higher than the position of the reception electrode  33 . The reception electrode  31  may be disposed at a lower position than the reception electrodes  32  and  33 , and the reception electrode  32  may be disposed at a lower position than the reception electrode  33 . The “height direction” is a direction along a vertical direction in a normal use state of the liquid discharge device  1 A. 
     The reception electrode  31  is disposed at a height position H 1 . The height position H 1  is an example of a first height position. For example, in the height direction, a central position of the reception electrode  31  is disposed at the height position H 1 . A lower end of the reception electrode  31  may be disposed at the height position H 1 , and the other part of the reception electrode  31  may be disposed at the height position H 1 . 
     The reception electrode  32  is disposed at a height position H 2 . The height position H 2  is an example of a second height position. For example, in the height direction, a central position of the reception electrode  32  is disposed at the height position H 2 . A lower end of the reception electrode  32  may be disposed at the height position H 2 , and the other part of the reception electrode  32  may be disposed at the height position H 2 . 
     The reception electrode  33  is disposed at a height position H 3 . The height position H 3  is an example of a third height position. For example, in the height direction, a central position of the reception electrode  33  is disposed at the height position H 3 . A lower end of the reception electrode  33  may be disposed at the height position H 3 , and the other part of the reception electrode  33  may be disposed at the height position H 3 . 
     The transmission electrode  22  and the reception electrode  31  form a parallel flat plate, and compose a capacitor  71 . The transmission electrode  22  and the reception electrode  32  form a parallel flat plate, and compose a capacitor  72 . The transmission electrode  22  and the reception electrode  33  form a parallel flat plate, and compose a capacitor  73 . The capacitors  71  to  73  may have the same structure or different structures. 
     Electrostatic capacitance C [F] of the capacitors  71  to  73  is expressed by the following Equation (1).
 
 C=ε   0 ε 1   S/d   (1)
 
     ε 0  is a permittivity of vacuum. ε 1  is a relative permittivity due to an object existing between the electrodes of the capacitors  71  to  73 . The electrostatic capacitance C of the capacitors  71  to  73  differs depending on the relative permittivity ε 1  of the object existing between the electrodes of the capacitors  71  to  73 . The relative permittivity ε 1  changes depending on a ratio of the ink  2  and air existing between the electrodes of the capacitors  71  to  73 . A relative permittivity ε ink  of the ink  2  is larger than a relative permittivity of ε air . The relative permittivity ε ink  of the ink  2  is, for example, 80, and the relative permittivity ε air  of air is almost 0. 
     An AC power supply  12  is electrically coupled to the transmission electrode  22 . The AC power supply  12  outputs, for example, a pulse wave of 3.3 [V] as a transmission signal to the transmission electrode  22 .  FIG.  4    is a graph showing a relationship between the liquid level of the ink  2  and output voltages of the capacitors  71  to  73 . A horizontal axis indicates the liquid level of the ink  2 , and indicates that the liquid level is higher on a right side in the drawing. A vertical axis indicates the output voltage [V] of the capacitor, and indicates that the voltage is higher on an upper side in the drawing. 
     A liquid level range LV 1  is a range from a lower end to an upper end of the capacitor  71  in the height direction. A liquid level range LV 2  is a range from a lower end to an upper end of the capacitor  72  in the height direction. A liquid level range LV 3  is a range from a lower end to an upper end of the capacitor  73  in the height direction. The liquid level range LV 1  is set to the highest position, and the liquid level range LV 2  and the liquid level range LV 3  become lower positions in this order. 
     When air exists between the electrodes of the capacitors  71  to  73  and the ink  2  does not exist, the output voltage V out  from the capacitors  71  to  73  is V L  [V]. The output voltage V out  increases as a ratio of the ink  2  which exists between the electrodes of the capacitors  71  to  73  increases. When a space between the electrodes of the capacitors  71  to  73  is filled with the ink  2  and air does not exist, the output voltage V out  is V H  [V]. For example, when the output voltage V out  becomes a predetermined threshold value V th , it can be regarded that the liquid level L of the ink  2  exists between the liquid level ranges LV 1  to LV 3  including the height positions H 1  to H 3  in which the capacitors  71  to  73  are disposed. The threshold value V th  is a value which is equal to or larger than V L  and is equal to or less than V H . For example, when V L  is 0 [%] and V H  is 100 [%], the threshold value V th  may be a value of 50%, a value of 30%, or a value of 70%, or another value. 
     When an output voltage V 31  from the capacitor  71  is the threshold value V th , the liquid level L of the ink  2  exists in the liquid level range LV 1 . When an output voltage V 32  from the capacitor  72  is the threshold value V th , the liquid level L of the ink  2  exists in the liquid level range LV 2 . When an output voltage V 33  from the capacitor  73  is the threshold value V th , the liquid level L of the ink  2  exists in the liquid level range LV 3 . 
     Next, the detection section  50  will be described.  FIG.  5    is a circuit diagram of the storage amount detection device  20 A.  FIG.  6    is a block diagram of the storage amount detection device  20 A. As shown in  FIG.  5   , the detection section  50  includes a selector circuit  36 A, a buffer circuit  51 , a BPF  52 , an S/H  53 , an LPF  54 , and an amplifier circuit  55 . The detection section  50  includes a filter circuit  37  that removes a predetermined frequency component from an input electric signal. The detection section  50  includes the BPF  52  and the LPF  54  as the filter circuit  37 . 
     The selector circuit  36 A is electrically coupled to input terminals  41  to  43  and an output terminal  40 A. 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 coupled to the reception electrode  31 . The input terminal  42  is electrically coupled to the reception electrode  32 . The input terminal  43  is electrically coupled to the reception electrode  33 . 
     The selector circuit  36 A switches whether or not to electrically couple the output terminal  40 A to at least one of the input terminals  41  to  43 . The output terminal  40 A is electrically coupled to at least one of the input terminals  41  to  43 . The selector circuit  36 A electrically couples the reception electrode  31  to the output terminal  40 A by electrically coupling the input terminal  41  to the output terminal  40 A. The selector circuit  36 A electrically couples the reception electrode  32  to the output terminal  40 A by electrically coupling the input terminal  42  to the output terminal  40 A. The selector circuit  36 A electrically couples the reception electrode  33  to the output terminal  40 A by electrically coupling the input terminal  43  to the output terminal  40 A. In this way, the selector circuit  36 A switches whether or not to electrically couple at least one of the reception electrodes  31  to  33 . A bias circuit  48  is electrically coupled to a subsequent stage of the selector circuit  36 A. 
     The buffer circuit  51  is electrically coupled to the subsequent stage of the selector circuit  36 A. The buffer circuit  51  is electrically coupled to the output terminal  40 A of the selector circuit  36 A. Since the impedances of the reception electrodes  31  to  33  are high, the buffer circuit  51  performs impedance conversion. 
     The BPF  52  includes a bandpass filter circuit. The BPF  52  is electrically coupled to a subsequent stage of the buffer circuit  51 . The BPF  52  passes a frequency component of a predetermined band in the input electric signal, and removes frequency components of the other bands. 
     The S/H  53  includes a sample hold circuit. The S/H  53  is electrically coupled to a subsequent stage of the BPF  52 . An electric signal output from the BPF  52  is input to the S/H  53 . The S/H  53  samples the electric signal for each predetermined cycle and holds the electric signal at a constant value until an operation of A/D conversion ends. Further, the S/H  53  is electrically coupled to the AC power supply  12 . A pulse wave of 3.3 V is input to the S/H  53  from the AC power supply  12 . 
     The LPF  54  includes a low-pass filter circuit. The LPF  54  is electrically coupled to a subsequent stage of the S/H  53 . An electric signal output from the S/H  53  is input to the LPF  54 . The LPF  54  removes a high frequency component from the input electric signal. The noise contained in the high frequency component is removed by the LPF 54 . 
     The amplifier circuit  55  is electrically coupled to a subsequent stage of the LPF  54 . An electric signal output from the LPF  54  is input to the amplifier circuit  55 . The amplifier circuit  55  amplifies the input electric signal. The amplified electric signal is input to the control section  60  in a subsequent stage. 
     The detection section  50  includes an A/D converter  38 . The A/D converter  38  converts an analog electric signal, which is the input electric signal, into a digital electric signal. The analog electric signal input to the A/D converter  38  is converted into the digital electric signal and is output. The A/D converter  38  is coupled to a subsequent stage of the amplifier circuit  55 . The digital electric signal output from the A/D converter  38  is input to the control section  60 . 
     Next, the control section  60  will be described. As shown in  FIG.  6   , the control section  60  includes, for example, a processing circuit  61 , such as a Central Processing Unit (CPU) or a Field Programmable Gate Array (FPGA), 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 . Further, the storage circuit  62  functions as a work area of the processing circuit  61 . The processing circuit  61  reads the control program from the storage circuit  62 . The processing circuit  61  functions as a control center of the liquid discharge device  1 A by executing the read control program. 
     The control section  60  includes the detection circuit  63 . The detection circuit  63  detects the storage amount of the ink  2  in the storage section  21 A based on the output from the output terminal  40 A. The detection circuit  63  detects the storage amount of the ink  2  based on a determination result based on the output from the output terminal  40 A in a state in which the output terminal  40 A and the reception electrode  31  are coupled to each other, a determination result based on the output from the output terminal  40 A in a state in which the output terminal  40 A and the reception electrode  32  are coupled to each other, and a determination result based on the output from the output terminal  40 A in a state in which the output terminal  40 A and the reception electrode  33  are coupled to each other. The detection result of the storage amount of the ink  2  by the detection circuit  63  will be described later with reference to  FIG.  31   . 
     Next, the determination result based on the output from the output terminal  40 A in the state in which the output terminal  40 A and the reception electrode  31  are coupled to each other will be described. The detection circuit  63  determines whether or not the storage amount of the ink  2  is equal to or larger than a first amount based on the electric signal output from the output terminal  40 A in the state in which the reception electrode  31  is coupled. When an output voltage V 31  of the capacitor  71  exceeds the threshold value V th , the detection circuit  63  determines that the liquid level L is equal to or higher than the height position H 1  and the storage amount of the ink  2  is equal to or larger than the first amount. When the liquid level L is equal to or higher than the height position H 1 , the detection circuit  63  determines that the storage amount is equal to or larger than the first amount. When the liquid level L is less than the height position H 1 , the detection circuit  63  determines that the storage amount is less than the first amount. When the height position of the liquid level L of the ink  2  is detected, the storage amount of the ink  2  can be detected. The detection circuit  63  may arbitrarily set the height position of the liquid level L according to a value of the threshold value V th . When the output voltage V 31  exceeds the threshold value V th , the detection circuit  63  may determine that the storage amount of the ink  2  is the first amount. 
     Next, the determination result based on the output from the output terminal  40 A in the state in which the output terminal  40 A and the reception electrode  32  are coupled to each other will be described. The detection circuit  63  determines whether or not the storage amount of the ink  2  is equal to or larger than a second amount based on the output from the output terminal  40 A in the state in which the reception electrode  32  is coupled. When the output voltage V 32  of the capacitor  72  exceeds the threshold value V th , the detection circuit  63  determines that the liquid level L is equal to or higher than the height position H 2  and the storage amount of the ink  2  is equal to or larger than the second amount. When the liquid level L is equal to or higher than the height position H 2 , the detection circuit  63  determines that the storage amount is equal to or larger than the second amount. When the liquid level L is less than the height position H 2 , the detection circuit  63  determines that the storage amount is less than the second amount. 
     Next, the determination result based on the output from the output terminal  40 A in the state in which the output terminal  40 A and the reception electrode  33  are coupled to each other will be described. The detection circuit  63  determines whether or not the storage amount of the ink  2  is equal to or larger than a third amount based on the output from the output terminal  40 A in the state in which the reception electrode  33  is coupled. When the output voltage V 33  of the capacitor  73  exceeds the threshold value V th , the detection circuit  63  determines that the liquid level L is equal to or higher than the height position H 3 , and the storage amount of the ink  2  is equal to or larger than the third amount. When the liquid level L is equal to or higher than the height position H 3 , the detection circuit  63  determines that the storage amount is equal to or larger than the third amount. When the liquid level L is less than the height position H 3 , the detection circuit  63  determines that the storage amount is less than the third amount. 
     Next, a case where the detection result of the storage amount becomes an error will be described. For example, when the determination result based on the output from the output terminal  40 A includes an error, the detection result of the storage amount based on the determination result becomes an error. The detection circuit  63  determines that the detection result of the storage amount is error when it is determined that the storage amount of ink  2  is equal to or larger than the first amount based on the output from the output terminal  40 A in the state in which the reception electrode  31  is coupled and when it is determined that the storage amount of the ink  2  is less than the third amount based on the output from the output terminal  40 A in the state in which the reception electrode  32  is coupled. 
     The detection circuit  63  determines that the detection result of the storage amount is error when it is determined that the storage amount of the ink  2  is less than the first amount based on the electric signal output from the output terminal  40 A in the state in which the reception electrode  31  is coupled, when it is determined that the storage amount of the ink  2  is equal to or larger than the second amount based on the electric signal output from the output terminal  40 A in the state in which the reception electrode  32  is coupled, and when it is determined that the storage amount of the ink  2  is less than the third amount based on the electric signal output from the output terminal  40 A in the state in which the reception electrode  33  is coupled. 
     The notification section  11  is electrically coupled to the control section  60  and displays the detection result by the detection circuit  63 . The notification section  11  displays the storage amount of the ink  2 . The notification section  11  displays an error message indicating that the detection result of the storage amount is error. 
     Next, an operation in the selector circuit  36 A will be described with reference to  FIG.  7   .  FIG.  7    is a circuit diagram including the selector circuit  36 A. The selector circuit  36 A includes switches SW 1  to SW 3 . The selector circuit  36 A receives selection signals SG 1  to SG 3 , and switches the reception electrodes  31  to  33  used to detect the liquid level L according to the received selection signals SG 1  to SG 3 . The selector circuit  36 A may switch the reception electrodes  31  to  33  according to the other states regardless of the selection signals SG 1  to SG 3 . 
     The switch SW 1  is provided between the input terminal  41  and the output terminal  40 A. The switch SW 2  is provided between the input terminal  42  and the output terminal  40 A. The switch SW 3  is provided between the input terminal  43  and the output terminal  40 A. 
     A decoder DC 1  is electrically coupled to the selector circuit  36 A. The control section  60  transmits, to the decoder DC 1 , command signals SG-A and SG-B that designate any of the reception electrodes  31  to  33  used to measure the liquid level L of the ink  2 . 
     When the command signals SG-A and SG-B designate the reception electrode  31 , the decoder DC 1  sets the selection signal SG 1  to the H level and sets the selection signals SG 2  and SG 3  to the L level. When the command signals SG-A and SG-B designate the reception electrode  32 , the decoder DC 1  sets the selection signal SG 2  to the H level and sets the selection signals SG 1  and SG 3  to the L level. When the command signals SG-A and SG-B designate the reception electrode  33 , the decoder DC 1  sets the selection signal SG 3  to the H level and sets the selection signals SG 1  and SG 2  to the L level. 
     The switch SW 1  is turned on when the selection signal SG 1  is at the H level and electrically couples the input terminal  41  to the output terminal  40 A. The switch SW 1  is turned off when the selection signal SG 1  is at the L level and electrically disconnects the input terminal  41  from the output terminal  40 A. 
     The switch SW 2  is turned on when the selection signal SG 2  is at the H level and electrically couples the input terminal  42  to the output terminal  40 A. The switch SW 2  is turned off when the selection signal SG 2  is at the L level and electrically disconnects the input terminal  42  from the output terminal  40 A. 
     The switch SW 3  is turned on when the selection signal SG 3  is at the H level and electrically couples the input terminal  43  to the output terminal  40 A. The switch SW 3  is turned off when the selection signal SG 3  is at the L level and electrically disconnects the input terminal  43  from the output terminal  40 A. 
     Next, an error determination procedure in the detection circuit  63  will be described with reference to  FIG.  8   .  FIG.  8    is a flowchart showing the error determination procedure in the detection circuit  63 . First, in step S 21 , the detection circuit  63  determines whether or not the storage amount of the ink  2  is equal to or larger than the first amount based on the electric signal output from the output terminal  40 A in the state in which the reception electrode  31  is coupled. When the storage amount is equal to or larger than the first amount, the process proceeds to step S 22 . When the storage amount is not equal to or larger than the first amount, it is determined that the storage amount is less than the first amount and the process proceeds to step S 24 . 
     In step S 22 , the detection circuit  63  determines whether or not the storage amount of the ink  2  is less than the second amount based on the electric signal output from the output terminal  40 A in the state in which the reception electrode  32  is coupled. When the storage amount is less than the second amount, the process proceeds to step S 23 , and it is determined that detection of the storage amount is error. When the storage amount is equal to or larger than the second amount, the detection circuit  63  ends the process here. 
     In step S 24 , the detection circuit  63  determines whether or not the storage amount of the ink  2  is equal to or larger than the second amount based on the electric signal output from the output terminal  40 A in the state in which the reception electrode  32  is coupled. When the storage amount is equal to or larger than the second amount, the process proceeds to step S 25 , and, when the storage amount is not equal to or larger than the second amount, the detection circuit  63  ends the process here. 
     In step S 25 , the detection circuit  63  determines whether or not the storage amount of the ink  2  is less than the third amount based on the electric signal output from the output terminal  40 A in the state in which the reception electrode  33  is coupled. When the storage amount is less than the third amount, the process proceeds to step S 26 , and it is determined that the detection of the storage amount is error. When the storage amount is equal to or larger than the third amount, the detection circuit  63  ends the process here. The processing procedure shown in  FIG.  8    can be arbitrarily changed. For example, the detection circuit  63  may determine whether or not the storage amount is equal to or larger than the second amount after determining whether or not the storage amount is equal to or larger than the third amount. 
     Since the storage amount detection device  20 A according to the first embodiment includes the selector circuit  36 A, it is possible to switch whether or not to electrically couple to at least one of the reception electrodes  31  to  33 . In the storage amount detection device  20 A, it is not necessary to provide a determination circuit for each of the reception electrodes  31  to  33 , so that a circuit substrate can be miniaturized. In the storage amount detection device  20 A, it is not necessary to perform correction for suppressing a variation in a circuit characteristic that occurs when a plurality of determination circuits are used, so that the circuit substrate can be miniaturized and detection accuracy of the storage amount can be improved. 
     Since the storage amount detection device  20 A includes the filter circuit  37  at the subsequent stage of the selector circuit  36 A, noise can be removed from the electric signal output from the output terminal  40 A. In the storage amount detection device  20 A, the storage amount can be detected based on the electric signal from which noise is removed, so that the detection accuracy of the storage amount can be improved. 
     In the liquid discharge device  1 A, which is a serial-type ink jet printing device, the liquid level L of the ink  2  stored in the storage section  21 A is fluctuated when the carriage  6  reciprocates. When the liquid level L fluctuates, the electrostatic capacitance of the capacitors  71  to  73  changes. According to the storage amount detection device  20 A, the noise caused by the fluctuation of the liquid level L can be removed by the filter circuit  37 , so that the detection accuracy of the storage amount can be improved. 
     Next, a coupling circuit  80  will be described. As shown in  FIG.  2   , the storage amount detection device  20 A includes the coupling circuit  80 . The coupling circuit  80  couples at least one of the reception electrodes  31  to  33 , which are not electrically coupled to the output terminal  40 A, to a constant voltage terminal  14 . The coupling circuit  80  couples the reception electrodes  31  to  33 , which are not electrically coupled to the output terminal  40 A, of the reception electrodes  31  to  33  to the constant voltage terminal  14 . The coupling circuit  80  does not couple the reception electrodes  31  to  33 , which are coupled to the output terminal  40 A, to the constant voltage terminal  14 . 
     The coupling 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 to electrically couple the input terminal  41  to the constant voltage terminal  14 . The switch circuit  82  switches whether or not to couple the input terminal  42  to the constant voltage terminal  14 . The switch circuit  83  switches whether or not to couple the input terminal  43  to the constant voltage terminal  14 . The coupling circuit  80  electrically couples the reception electrodes  31  to  33 , which are not used to detect the liquid level L of the ink  2 , to the constant voltage terminal  14 . The coupling circuit  80  electrically disconnects the reception electrodes  31  to  33 , which are used to detect the liquid level L, from the constant voltage terminal  14 . 
     A decoder DC 2  is electrically coupled to the coupling circuit  80 . The control section  60  transmits, to the decoder DC 2 , command signals SG-C and SG-D indicating any of the reception electrodes  31  to  33  used to measure the liquid level L of the ink  2 . The decoder DC 2  that receives the command signals SG-C and SG-D supplies a selection signal SG 4  to the switch circuit  81 , supplies a selection signal SG 5  to the switch circuit  82 , and supplies a selection signal SG 6  to the switch circuit  83 . 
     When the reception electrode  31  is indicated by the command signals SG-C and SG-D, the decoder DC 2  sets the selection signal SG 4  to the L level and sets the selection signals SG 5  and SG 6  to the H level. When the reception electrode  32  is indicated by the command signals SG-C and SG-D, the decoder DC 2  sets the selection signal SG 5  to the L level and sets the selection signals SG 4  and SG 6  to the H level. When the reception electrode  33  is indicated by the command signals SG-C and SG-D, the decoder DC 2  sets the selection signal SG 6  to the L level and sets the selection signals SG 4  and SG 5  to the H level. 
     The switch circuit  81  is turned on when the selection signal SG 4  is at the H level and electrically couples the reception electrode  31  to the constant voltage terminal  14 . The switch circuit  81  is turned off when the selection signal SG 4  is at the L level and electrically disconnects the reception electrode  31  from the constant voltage terminal  14 . 
     The switch circuit  82  is turned on when the selection signal SG 5  is at the H level and electrically couples the reception electrode  32  to the constant voltage terminal  14 . The switch circuit  82  is turned off when the selection signal SG 5  is at the L level and electrically disconnects the reception electrode  32  from the constant voltage terminal  14 . 
     The switch circuit  83  is turned on when the selection signal SG 6  is at the H level and electrically couples the reception electrode  33  to the constant voltage terminal  14 . The switch circuit  83  is turned off when the selection signal SG 6  is at the L level and electrically disconnects the reception electrode  33  from the constant voltage terminal  14 . 
       FIGS.  9  to  11    are circuit diagrams showing coupling relationships between the reception electrodes  31  to  33 , which are not coupled to the output terminal  40 A, and the constant voltage terminal  14 . The coupling circuit  80  performs switching such that all the reception electrodes  31  to  33 , which are not electrically coupled to the output terminal  40 A, among the reception electrodes  31  to  33  are electrically coupled to the constant voltage terminal  14 . The coupling circuit  80  switches whether or not to electrically disconnect only one of the reception electrodes  31  to  33  from the constant voltage terminal  14 . 
     As shown in  FIG.  9   , when the reception electrode  31  is selected to detect the liquid level L of the ink  2 , the selector circuit  36 A electrically couples the input terminal  41  to the output terminal  40 A, and does not couple the input terminal  42  and the input terminal  43  to the output terminal  40 A. The switch circuit  82  electrically couples the input terminal  42  to the constant voltage terminal  14 , the switch circuit  83  electrically couples the input terminal  43  to the constant voltage terminal  14 . The reception electrode  31  is not electrically coupled to the constant voltage terminal  14 . The reception electrode  31 , which is electrically coupled to the output terminal  40 A, is not shielded by the ground potential. 
     As shown in  FIG.  10   , when the reception electrode  32  is selected to detect the liquid level L of the ink  2 , the selector circuit  36 A electrically couples the input terminal  42  to the output terminal  40 A, and does not couple the input terminal  41  and the input terminal  43  to the output terminal  40 A. The switch circuit  81  electrically couples the input terminal  41  to the constant voltage terminal  14 , and the switch circuit  83  electrically couples the input terminal  43  to the constant voltage terminal  14 . The reception electrode  32  is not electrically coupled to the constant voltage terminal  14 . The reception electrode  32 , which is electrically coupled to the output terminal  40 A, is not shielded by the ground potential. 
     As shown in  FIG.  11   , when the reception electrode  33  is selected to detect the liquid level L of the ink  2 , the selector circuit  36 A electrically couples the input terminal  43  to the output terminal  40 A, and does not couple the input terminal  41  and the input terminal  42  to the output terminal  40 A. The switch circuit  81  electrically couples the input terminal  41  to the constant voltage terminal  14 , the switch circuit  82  electrically couples the input terminal  42  to the constant voltage terminal  14 . The reception electrode  33  is not electrically coupled to the constant voltage terminal  14 . The reception electrode  33 , which is electrically coupled to the output terminal  40 A, is not shielded by the ground potential. 
     According to the storage amount detection device  20 A, the reception electrode  30 , which is electrically coupled to the output terminal  40 A, is not electrically coupled to the constant voltage terminal  14 , and the reception electrode  30 , which is not electrically coupled to the output terminal  40 A, is electrically coupled to the constant voltage terminal  14 . Therefore, the reception electrode  30  that is not used to detect the liquid level L can be prevented from being a state of being electrically floated. In a state in which the reception electrode  30 , which is not used, is floated, there is a problem in that residual charges and the like affect detection of the liquid level L by the other reception electrodes  30  when the reception electrode  30  is electrically coupled to the output terminal  40 A. In the storage amount detection device  20 A, since the reception electrode  30  in the unused state is electrically coupled to the constant voltage terminal  14 , the influence of the residual charge and the like can be avoided. As a result, the storage amount detection device  20 A can improve detection accuracy of the liquid level L. 
     Next, shield electrodes  91  to  98  that cover the transmission electrode  22  and the reception electrode  30  will be described with reference to  FIGS.  12  to  15   .  FIG.  12    is a cross-sectional diagram of the storage section  21 A, that is, a diagram showing the shield electrodes  91  to  98  that cover the transmission electrode  22  and the reception electrode  30 .  FIG.  13    is a cross-sectional diagram taken along the line XIII-XIII in  FIG.  12   .  FIG.  14    is a diagram showing the transmission electrode  22  and the shield electrodes  92  and  93 .  FIG.  15    is a diagram showing the reception electrode  30  and the shield electrodes  95  to  98 . 
     As shown in  FIG.  12   , the transmission electrode  22  is shielded by the shield electrodes  91  to  93 . The shield electrodes  91  to  93  are coupled to the ground potential. The reception electrode  30  is shielded by the shield electrodes  94  to  98 . The shield electrodes  94  to  98  are coupled to the ground potential. As the constituent material of the shield electrodes  91  to  98 , the same constituent material as the constituent materials of the transmission electrode  22  and the reception electrodes  31  to  33  can be used. 
     The transmission electrode  22  includes a first surface  22   a  and a second surface  22   b  that are separated from each other in the Y-axis direction. The first surface  22   a  is a surface on a side of the storage section  21 A, and the second surface  22   b  is a surface on a side opposite to the storage section  21 A. The transmission electrode  22  includes a third surface  22   c  and a fourth surface  22   d  that are separated from each other in the Z-axis direction. The third surface  22   c  is an upper surface, and the fourth surface  22   d  is a lower surface. 
     The shield electrode  91  is disposed to cover the second surface  22   b  of the transmission electrode  22 . The shield electrode  91  and the transmission electrode  22  are separated from each other in the Y-axis direction. A gap is formed between the shield electrode  91  and the transmission electrode  22 . An insulator may be disposed between the shield electrode  91  and the transmission electrode  22 . The shield electrode  91  has a larger area than the transmission electrode  22 . The shield electrode  91  is disposed to cover an entire surface of the second surface  22   b  of the transmission electrode  22 . The shield electrode  91  may cover a part of the second surface  22   b  of the transmission electrode  22 . 
     The shield electrode  92  is disposed to cover the third surface  22   c  of the transmission electrode  22 . The shield electrode  92  is disposed on an upper side of the third surface  22   c . An insulator is disposed between the shield electrode  92  and the transmission electrode  22 . A gap may be formed between the shield electrode  92  and the transmission electrode  22 . The shield electrode  91  may be formed to cover an entire surface of the third surface  22   c , or may be formed to cover a part of the third surface  22   c.    
     The shield electrode  93  is disposed to cover the fourth surface  22   d  of the transmission electrode  22 . The shield electrode  93  is disposed on a lower side of the fourth surface  22   d . An insulator is disposed between the shield electrode  93  and the transmission electrode  22 . A gap may be formed between the shield electrode  93  and the transmission electrode  22 . The shield electrode  93  may be formed to cover an entire surface of the fourth surface  22   d , or may be formed to cover a part of the fourth surface  22   d . The shield electrodes may be disposed on both sides of the transmission electrode  22  in the X-axis direction. 
     The reception electrode  31  includes a first surface  31   a  and a second surface  31   b  that are separated from each other in the Y-axis direction. The first surface  31   a  is a surface on a side of the storage section  21 A, and the second surface  31   b  is a surface on a side opposite to the storage section  21 A. The reception electrode  31  includes a third surface  31   c  and a fourth surface  31   d  that are separated from each other in the Z-axis direction. The first surface  31   a  is a surface on a side of the storage section  21 A, and the second surface  31   b  is a surface on a side opposite to the storage section  21 A. The third surface  31   c  is an upper surface, and the fourth surface  31   d  is a lower surface. 
     Similarly, the reception electrode  32  includes a first surface  32   a , a second surface  32   b , a third surface  32   c , and a fourth surface  32   d . The first surface  32   a  and the second surface  32   b  are separated from each other in the Y-axis direction. The third surface  32   c  and the fourth surface  32   d  are separated from each other in the Z-axis direction. The first surface  32   a  is a surface on a side of the storage section  21 A, and the second surface  32   b  is a surface on a side opposite to the storage section  21 A. The third surface  32   c  is an upper surface, and the fourth surface  32   d  is a lower surface. 
     The reception electrode  33  includes a first surface  33   a , a second surface  33   b , a third surface  33   c , and a fourth surface  33   d . The first surface  33   a  and the second surface  33   b  are separated from each other in the Y-axis direction. The third surface  33   c  and the fourth surface  33   d  are separated from each other in the Z-axis direction. The first surface  33   a  is a surface on a side of the storage section  21 A, and the second surface  33   b  is a surface on a side opposite to the storage section  21 A. The third surface  33   c  is an upper surface, and the fourth surface  33   d  is a lower surface. 
     The shield electrode  94  is disposed to cover the second surface  31   b  of the reception electrode  31 , the second surface  32   b  of the reception electrode  32 , and the second surface  33   b  of the reception electrode  33 . The shield electrode  94  and the reception electrode  30  are separated from each other in the Y-axis direction. A gap is formed between the shield electrode  91  and the reception electrode  30 . An insulator may be disposed between the shield electrode  94  and the reception electrode  30 . The shield electrode  94  is disposed to cover an entire surface including the second surface  31   b  of the reception electrode  31 , the second surface  32   b  of the reception electrode  32 , and the second surface  33   b  of the reception electrode  33 . The shield electrode  94  may cover a part of the second surface  31   b  of the reception electrode  31 , the second surface  32   b  of the reception electrode  32 , and the second surface  33   b  of the reception electrode  33 . 
     The shield electrode  95  is disposed to cover the third surface  31   c  of the reception electrode  31 . The shield electrode  95  is disposed on an upper side of the third surface  31   c . An insulator is disposed between the shield electrode  95  and the reception electrode  31 . A gap may be formed between the shield electrode  95  and the reception electrode  31 . The shield electrode  95  may be formed to cover an entire surface of the third surface  31   c , or may be formed to cover a part of the third surface  31   c.    
     The shield electrode  96  is disposed between the reception electrode  31  and the reception electrode  32  in the Z-axis direction. The shield electrode  96  is disposed to cover the fourth surface  31   d  of the reception electrode  31  and the third surface  32   c  of the reception electrode  32 . An insulator is disposed between the shield electrode  96  and the reception electrode  31 . An insulator is disposed between the shield electrode  96  and the reception electrode  32 . A gap may be formed between the shield electrode  96  and the reception electrode  31 . A gap may be formed between the shield electrode  96  and the reception electrode  32 . The shield electrode  96  may be formed to cover an entire surface including the fourth surface  31   d  of the reception electrode  31  and the third surface  32   c  of the reception electrode  32 , and may be formed to cover a part of the fourth surface  31   d  and the third surface  32   c.    
     The shield electrode  97  is disposed between the reception electrode  32  and the reception electrode  33  in the Z-axis direction. The shield electrode  97  is disposed to cover the fourth surface  32   d  of the reception electrode  32  and the third surface  33   c  of the reception electrode  33 . An insulator is disposed between the shield electrode  97  and the reception electrode  32 . An insulator is disposed between the shield electrode  97  and the reception electrode  33 . A gap may be formed between the shield electrode  97  and the reception electrode  32 . A gap may be formed between the shield electrode  97  and the reception electrode  33 . The shield electrode  97  may be formed to cover an entire surface including the fourth surface  32   d  of the reception electrode  32  and the third surface  33   c  of the reception electrode  33 , and may be formed to cover a part of the fourth surface  32   d  and the third surface  33   c.    
     The shield electrode  98  is disposed to cover the fourth surface  33   d  of the reception electrode  33 . The shield electrode  98  is disposed on a lower side of the fourth surface  33   d . An insulator is disposed between the shield electrode  98  and the reception electrode  33 . A gap may be formed between the shield electrode  98  and the reception electrode  33 . The shield electrode  98  may be formed to cover an entire surface of the fourth surface  33   d , or may be formed to cover a part of the fourth surface  33   d.    
     According to the storage amount detection device  20 A, the transmission electrode  22  and the reception electrode  30  are covered by the shield electrodes  91  to  98 , so that the influence due to noise is reduced. 
     Next, the influence due to noise will be described with reference to  FIGS.  16  to  18   .  FIG.  16    is a cross-sectional diagram of the storage section  21 A, that is, a diagram showing lines of electric force emitted from the transmission electrode  22 .  FIG.  17    is a diagram showing the enlarged reception electrode  30 , that is, a diagram showing the lines of electric force received by the reception electrode  30 .  FIG.  18    is a cross-sectional diagram of the plurality of storage sections  21 A and  21 B, that is, a diagram showing lines of electric force emitted from a plurality of transmission electrodes  22 . In each drawing, the lines of electric force are indicated by broken lines with arrows. 
     As shown in  FIG.  16   , the lines of electric force are emitted from the first surface  22   a , the second surface  22   b , the third surface  22   c , and the fourth surface  22   d  of the transmission electrode  22 . The lines of electric force, which are emitted from the first surface  22   a  and extend in the Y-axis direction, may be received by the reception electrode  31 , the reception electrode  32 , and the reception electrode  33 . There is a case where lines of electric force radiated from the third surface  22   c  and the fourth surface  22   d  interfere with surrounding conductors, so that noise is generated. As a surrounding conductor that has a problem of the interference, there is a housing grounding. 
     In  FIG.  17   , the reception electrode  33  is shown, and the liquid level L of the ink  2  exists at a position which is a lower side than the fourth surface  33   d  of the reception electrode  33  and is close to the fourth surface  33   d . The liquid level L exists outside a range of the liquid level range LV 3 . When the lines of electric force radiated from the third surface  22   c  and the fourth surface  22   d  of the transmission electrode  22  interfere with the surrounding conductors, there is a problem in that a part of the lines of electric force that passes through the ink  2  is curved toward a side of the reception electrode  33  in the vicinity of the reception electrode  33  and is received by the fourth surface  33   d . Therefore, there is a case where a value of an output voltage L out  is not lower than VL [V] regardless that the liquid level L is on a lower side than the liquid level range LV. Therefore, there is a problem in that erroneous detection, in which the liquid level L exists within the liquid level range LV 3 , is performed. There is a problem in that the influence due to noise occurs. There is a problem in that the influence of noise also occurs in the reception electrode  31  and the reception electrode  32 , similarly to the reception electrode  33 . 
     As described above, in the storage amount detection device  20 A, the second surface  22   b , the third surface  22   c , and the fourth surface  22   d  of the transmission electrode  22  are covered by the shield electrodes  91  to  93 . The shield electrodes  91  to  93  suppress the lines of electric force emitted from the second surface  22   b , the third surface  22   c , and the fourth surface  22   d , so that the problem of interfering with the surrounding conductors is reduced. 
     In the storage amount detection device  20 A, the second surface  33   b , the third surface  33   c , and the fourth surface  33   d  of the reception electrode  33  are covered by the shield electrodes  94 ,  97 , and  98 . Therefore, the lines of electric force surrounding the reception electrode  33  are suppressed from being received by the second surface  33   b , the third surface  33   c , and the fourth surface  33   d . As described above, when the liquid level L exists on a lower side than the fourth surface  33   d , the lines of electric force that pass through the ink  2  are suppressed from being received by the fourth surface  33   d . Therefore, a decrease in detection accuracy of a value of the output voltage V out  is suppressed. As a result, detection accuracy of the height position of the liquid level L is improved. Since the reception electrode  31  and the reception electrode  32  are similarly covered by the shield electrodes  94  to  97 , the decrease in the detection accuracy of the value of the output voltage V out  is suppressed, so that the detection accuracy of the height position of the liquid level L is improved. Therefore, in the storage amount detection device  20 A, the storage amount of the ink  2  can be accurately detected. Further, in the storage amount detection device  20 A, the lines of electric force emitted from other conductors are prevented from being received by the reception electrodes  31  to  33 . 
     Next, with reference to  FIG.  18   , influence of noise when a plurality of storage sections  21 A and  21 B are provided will be described. As shown in  FIG.  18   , the storage section  21 A and the storage section  21 B are disposed to be separated from each other in the Y-axis direction. The transmission electrode  22  of the storage section  21 B is disposed next to the reception electrodes  31  to  33  of the storage section  21 A. 
     As shown in  FIG.  18   , the lines of electric force are emitted from the first surface  22   a , the second surface  22   b , the third surface  22   c , and the fourth surface  22   d  of the transmission electrode  22  of the storage section  21 B. The lines of electric force, which are emitted from the first surface  22   a  and extend in the Y-axis direction, may be received by the reception electrode  31 , the reception electrode  32 , and the reception electrode  33 . There is a problem in that a part of the lines of electric force emitted from the second surface  22   b  of the storage section  21 B is received by the reception electrode  30  of the storage section  21 A. 
     In the storage amount detection device  20 A, the second surface  33   b , the third surface  33   c , and the fourth surface  33   d  of the reception electrode  33  are covered by the shield electrodes  94 ,  97 , and  98 . Therefore, the lines of electric force emitted from the transmission electrode  22  of the adjacent storage section  21 B are suppressed from being received by the reception electrode  33  of the storage section  21 A. Therefore, a decrease in detection accuracy of a value of the output voltage V out  is suppressed. As a result, detection accuracy of the height position of the liquid level L is improved. Since the reception electrode  31  and the reception electrode  32  are similarly covered by the shield electrodes, the decrease in the detection accuracy of the value of the output voltage V out  is suppressed, so that the detection accuracy of the height position of the liquid level L is improved. Therefore, in the storage amount detection device  20 A, the storage amount of the ink  2  can be accurately detected. 
     Next, a switch circuit  13  and a noise detection mode will be described. As shown in  FIG.  2   , the storage amount detection device  20 A includes the switch circuit  13  coupled between the AC power supply  12  and the transmission electrode  22 . The storage amount detection device  20 A can switch between the 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  20 A switches the reception electrodes  31  to  33 , and executes the noise detection mode and the liquid level detection mode for each of the reception electrodes  31  to  33 . The storage amount detection device  20 A can alternately execute a measurement mode and the noise detection mode. 
     The control section  60  outputs a designation signal that designates an operation mode of the storage amount detection device  20 A. When receiving the designation signal, the switch circuit  13  performs switch OFF, cuts the coupling between the AC power supply  12  and the transmission electrode  22 , and executes the noise detection mode. After executing the noise detection mode, the switch circuit  13  performs switch ON, couples the AC power supply  12  to the transmission electrode  22  for conduction, and executes the measurement mode. 
     Next, a processing procedure in the storage amount detection device  20 A will be described with reference to  FIGS.  19  to  21   .  FIG.  19    is a flowchart showing the processing procedure of the storage amount detection device  20 A.  FIG.  20    is a flowchart showing a procedure in the noise detection mode.  FIG.  21    is a flowchart showing a procedure in the liquid level measurement mode. 
     As shown in  FIG.  19   , the storage amount detection device  20 A executes the noise detection mode as step S 31 . In the noise detection mode, the processes in steps S 41  to S 48  shown in  FIG.  20    are executed. In step S 41 , the switch circuit  13  performs switch OFF and cuts the coupling between the AC power supply  12  and the transmission electrode  22 . 
     In step S 42 , the reception electrode is selected. The selector circuit  36 A selects the reception electrodes  31  to  33  by coupling at least one of the input terminals  41  to  43  to the output terminal  40 A. In step S 43 , the AC power supply  12  outputs a transmission pulse to the S/H  53 . 
     In step S 44 , the control section  60  measures the output voltage V out  based on outputs from the selected reception electrodes  31  to  33 . The electric signals output from the reception electrodes  31  to  33  are input to the control section  60  after passing through the buffer circuit  51 , the BPF  52 , the S/H  53 , the LPF  54 , and the amplifier circuit  55 . The detection circuit  63  of the control section  60  calculates the output voltage V out  based on the output from the amplifier circuit  55 . 
     In step S 45 , the detection circuit  63  determines whether or not the output voltage V out  is less than a threshold value V thN . The threshold value V thN  is a determination threshold value for determining whether or not noise exists at the output voltage V out . When the output voltage V out  is less than the threshold value V thN , the process proceeds to step S 46 , the control section  60  records that noise does not exist. When the output voltage V out  is equal to or larger than the threshold value V thN , the process proceeds to step S 47 , and the control section  60  records that noise exists. In the subsequent step S 48 , the AC power supply  12  stops to output the transmission pulse to the S/H  53 . 
     After executing step S 48 , the noise detection mode ends, and step S 32  shown in  FIG.  19    is executed. In step S 32 , it is determined whether or not noise is detected in the noise detection mode. When being recorded that noise does not exist in step S 46 , the process proceeds to step S 33 , the liquid level detection mode is executed, and, when being recorded that noise exists in step S 47 , the process proceeds to step S 34 , a measurement error is recorded, and the liquid level detection mode is not executed. In a case of the measurement error, the storage amount detection device  20 A can provide a notification to the user by performing display using the notification section  11 . 
     In the ink liquid level detection mode of step S 33 , processes from step S 51  to step S 58 , which are shown in  FIG.  21   , are executed. In step S 51 , the switch circuit  13  performs switch ON, and couples the AC power supply  12  to the transmission electrode  22  for conduction. 
     In step S 52 , the reception electrodes  31  to  33  are selected. The selector circuit  36 A selects the reception electrodes  31  to  33  by coupling at least one of the input terminals  41  to  43  to the output terminal  40 A. In step S 53 , the AC power supply  12  outputs a transmission pulse to the S/H  53 . 
     In step S 54 , the control section  60  measures the output voltage V out  based on the outputs from the selected reception electrodes  31  to  33 . The electric signals output from the reception electrodes  31  to  33  are input to the control section  60  after passing through the buffer circuit  51 , the BPF  52 , the S/H  53 , the LPF  54 , and the amplifier circuit  55 . The detection circuit  63  of the control section  60  measures the output voltage V out . 
     In step S 55 , the detection circuit  63  determines whether or not the output voltage V out  is less than the threshold value V th . The threshold value V th  is a determination threshold value for determining whether or not the liquid level L of the ink  2  exists at a relevant height position. When the output voltage V out  is less than the threshold value V th , the process proceeds to step S 56 , and the control section  60  records that the liquid level L does not reach the height position of the selected reception electrode. When the output voltage V out  is equal to or larger than the threshold value V th , the process proceeds to step S 57 , and the control section  60  records that the liquid level L is equal to or higher than the height position of the selected reception electrode. In the following step S 58 , the AC power supply  12  stops the output of the transmission pulse to the S/H  53 . After executing step S 58 , the control section  60  ends the liquid level detection mode. 
     The storage amount detection device  20 A includes the switch circuit  13 , cuts the coupling between the AC power supply  12  and the transmission electrode  22 , thereby enabling the noise detection mode to be executed. In the storage amount detection device  20 A, when 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  20 A, the erroneous detection due to the influence of noise is prevented, so that a decrease in detection accuracy is avoided. 
     Since the storage amount detection device  20 A includes the selector circuit  36 A, it is not necessary to provide the detection circuits for the respective reception electrodes  31  to  33  in order to execute the noise detection mode, so that the circuit substrate can be miniaturized. 
     Next, with reference to  FIG.  22   , a processing procedure of the storage amount detection device  20 A according to a first modification example will be described.  FIG.  22    is a flowchart showing the processing procedure of the storage amount detection device  20 A according to the first modification example. The difference between the storage amount detection device  20 A according to the first modification example and the storage amount detection device  20 A according to the first embodiment is that the processing procedure shown in  FIG.  22    is executed instead of the processing procedure shown in  FIG.  19   . 
     First, as step S 61 , the control section  60  of the storage amount detection device  20 A resets an NG number count. The NG count number is the number of times recorded that noise exists in the noise detection mode. The NG count number is counted in step S 62 , which will be described later. After executing step S 61 , the process proceeds to step S 32 , and the storage amount detection device  20 A executes the noise detection mode shown in  FIG.  20   . 
     After executing the noise detection mode, the process proceeds to step S 33 , and, when noise detection is not performed, the liquid level detection mode of step S 34  is executed. When noise is detected in the noise detection mode, the process proceeds to step S 62  and the NG number is counted. The control section  60  adds “1” to the NG number. 
     Subsequently, in step S 63 , the control section  60  determines whether or not the NG number reaches the limit. The limit of the NG number can be set arbitrarily. When the NG number reaches the limit, the process proceeds to step S 34 , a measurement error is recorded, and the liquid level detection mode is not executed. 
     When the NG number does not reach the limit, the process proceeds to step S 64  and the waiting time is set. Next, in step S 65 , it is determined whether or not the waiting time elapses. When the waiting time does not elapse, the process in step S 65  is repeated, and, when the waiting time elapses, the process returns to step S 31  and the noise detection mode is executed. 
     In the storage amount detection device  20 A according to the first modification example, when noise is detected, the noise detection mode can be executed again after waiting for the elapse of the waiting time. Therefore, even when noise is detected, the liquid level detection mode can be executed after waiting for noise to be not detected. Therefore, reliability of the device can be improved. 
     Next, a storage amount detection device  20 A according to a second modification example will be described.  FIGS.  23  to  25    are schematic diagrams of a selector circuit  63 A of the storage amount detection device  20 A according to the second modification example. The difference between the storage amount detection device according to the second modification example and the storage amount detection device  20 A according to the first embodiment is that an operation of the selector circuit  36 A is different. 
     The selector circuit  36 A of the storage amount detection device  20 A according to the second modification example switches whether or not to electrically couple the output terminal  40 A to at least two of the input terminals  41  to  43 . As shown in  FIG.  23   , the selector circuit  36 A can switch to a state in which the input terminal  41  is electrically coupled to the output terminal  40 A and the input terminal  42  is electrically coupled to the output terminal  40 A. As shown in  FIG.  24   , the selector circuit  36 A can switch to a state in which the input terminal  42  is electrically coupled to the output terminal  40 A and the input terminal  43  is electrically coupled to the output terminal  40 A. As shown in  FIG.  25   , the selector circuit  36 A can switch to a state in which the input terminal  41  is electrically coupled to the output terminal  40 A and the input terminal  42  is electrically coupled to the output terminal  40 A. 
     In the storage amount detection device  20 A according to the second modification example, in a state in which the input terminal  41  and the input terminal  42  are coupled to the output terminal  40 A, a capacitor  74  is configured to include the reception electrode  31  and the reception electrode  32  as the reception electrodes. When the output voltage by the capacitor  74  exceeds the threshold value V th , the detection circuit  63  determines that the liquid level L exists in the liquid level range LV 1  or the liquid level range LV 2 . 
     In the storage amount detection device  20 A, in a state in which the input terminal  42  and the input terminal  43  are coupled to the output terminal  40 A, a capacitor  75  is configured to include the reception electrode  32  and the reception electrode  33  as the reception electrodes. When the output voltage by the capacitor  75  exceeds the threshold value V t h, the detection circuit  63  determines that the liquid level L exists in the liquid level range LV 2  or the liquid level range LV 3 . 
     In the storage amount detection device  20 A, in a state in which the input terminal  41  and the input terminal  43  are coupled to the output terminal  40 A, a capacitor  76  is configured to include the reception electrode  31  and the reception electrode  33  as the reception electrodes. When the output voltage by the capacitor  76  exceeds the threshold value V th , the detection circuit  63  determines that the liquid level L exists in the liquid level range LV 1  or the liquid level range LV 3 . 
     The storage amount detection device  20 A according to the second modification example also has the same effect as in the storage amount detection device  20 A of the first embodiment. 
     Next, a liquid discharge device  1 B according to a second embodiment will be described with reference to  FIGS.  26  and  27   . In the description of the second embodiment, the same description as in the above-described embodiment will not be repeated. 
       FIG.  26    is a schematic diagram of the liquid discharge device  1 B according to the second embodiment.  FIG.  27    is a schematic diagram of a storage amount detection device  20 B according to the second embodiment. The liquid discharge device  1 B includes a storage amount detection device  20 B. The liquid discharge device  1 B is a serial-type ink jet printer. The liquid discharge device  1 B includes a carriage  6  that can reciprocate. The carriage  6  stores four ink cartridges  15 A to  15 D that one-to-one correspond with four colors of ink. The carriage  6  is provided with respective discharge sections  4  for the four ink cartridges  15 A to  15 D. 
     The ink cartridge  15 A includes a storage section  21 A that stores yellow ink  2 . The ink cartridge  15 B includes a storage section  21 B that stores magenta ink  2 . The ink cartridge  15 C includes a storage section  21 C that stores cyan ink  2 . The ink cartridge  15 D includes a storage section  21 D that stores black ink  2 . 
     The storage amount detection device  20 B shown in  FIG.  27    is different from the storage amount detection device  20 A according to the first embodiment in that the storage amount detection device  20 B includes a plurality of storage sections  21 A to  21 D and a storage section selection circuit  45 . The storage sections  21 A to  21 D have the same configuration as the storage section  21 A of the first embodiment. The four storage sections  21 A to  21 D are provided with selector circuits  36 A to  36 D, respectively. The selector circuits  36 A to  36 D have output terminals  40 A to  40 D, respectively. The selector circuits  36 B to  36 D have the same configuration as the selector circuit  36 A according to the above-described embodiment, and the output terminals  40 B to  40 D have the same configuration as the output terminal  40 A according to the above-described embodiment. 
     The storage section selection circuit  45  includes a plurality of switch circuits  46 A to  46 D. The output terminal  47  of the storage section selection circuit  45  is electrically coupled to a buffer circuit  51  at a subsequent stage. 
     The storage section selection circuit  45  switches whether or not to couple the output terminal  47  to one of the plurality of selector circuits  36 A to  36 D. The switch circuit  46 A switches whether or not to electrically couple the selector circuit  36 A to the output terminal  47 . The switch circuit  46 A switches whether or not to electrically couple the selector circuit  36 A to the output terminal  47 . The switch circuit  46 B switches whether or not to electrically couple the selector circuit  36 B to the output terminal  47 . The switch circuit  46 C switches whether or not to electrically couple the selector circuit  36 C to the output terminal  47 . The switch circuit  46 D switches whether or not to electrically couple the selector circuit  36 D to the output terminal  47 . 
     The control section  60  outputs a command signal indicating ON/OFF of the switch circuits  46 A to  46 D. The command signal is input to the storage section selection circuit  45 . The storage section selection circuit  45  switches the switch circuits  46 A to  46 D based on the storage section selection signal. When detecting the liquid level L of the ink  2  stored in the storage section  21 A, the storage section selection circuit  45  performs switch ON of the switch circuit  46 A and electrically couples the selector circuit  36 A to the output terminal  47 . In this case, the storage section selection circuit  45  performs switch OFF on the remaining selector circuits  36 B to  38 D, and electrically disconnects the selector circuits  36 B to  36 D from the output terminal  47 . Therefore, only the selector circuit  36 A of the selector circuits  36 A to  36 D is electrically coupled to the output terminal  47 . 
     Similarly, when detecting the liquid level L of the ink  2  stored in the storage section  21 B, the storage section selection circuit  45  electrically couples the selector circuit  36 B to the output terminal  47 , and electrically disconnects the selector circuits  36 A,  36 C, and  36 D from the output terminal  47 . 
     When detecting the liquid level L of the ink  2  stored in the storage section  21 C, the storage section selection circuit  45  electrically couples the selector circuit  36 C to the output terminal  47 , and electrically disconnects the selector circuits  36 A,  36 B, and  36 D from the output terminal  47 . 
     When detecting the liquid level L of the ink  2  stored in the storage section  21 D, the storage section selection circuit  45  electrically couples the selector circuit  36 D to the output terminal  47 , and electrically disconnects the selector circuits  36 A,  36 B, and  36 C from the output terminal  47 . 
     According to the storage amount detection device  20 B according to the second embodiment, the storage section selection circuit  45  is provided, so that it is possible to switch whether or not couple the output terminal  47  to one of the plurality of selector circuits  36 A to  36 D. In the storage amount detection device  20 B, it is not necessary to provide respective detection circuits for the plurality of storage sections  21 A to  21 D, so that the circuit substrate can be miniaturized. In the storage amount detection device  20 B, it is not necessary to perform correction for suppressing variation in circuit characteristic occurring when a plurality of detection circuits are used, so that the circuit substrate can be miniaturized and the detection accuracy of the storage amount can be improved. 
     Next, a storage amount detection device  20 C according to a third modification example will be described with reference to  FIGS.  28  and  29   . The difference between the storage amount detection device according to the third modification example and the storage amount detection device  20 A according to the first embodiment is that the reception electrode  30  includes four reception electrodes  31  to  34 . The selector circuit  36 A includes an input terminal  44  that is electrically coupled to the reception electrode  34 . The reception electrode  34  is disposed at a lower height position than the reception electrodes  31  to  33 . 
     As shown in  FIG.  28   , the selector circuit  36 A of the storage amount detection device  20 C switches whether or not to electrically couple at least one of the input terminals  41  to  44  of the input terminals  41  to  44  to the output terminal  40 A. When the reception electrode  34  is selected to detect the liquid level L, the selector circuit  36 A electrically couples the output terminal  40 A to the reception electrode  34 , and electrically disconnects the output terminal  40 A from the reception electrodes  31  to  33 . 
     The detection circuit  63  determines whether or not the storage amount of the ink  2  is equal to or larger than a fourth amount based on the output from the output terminal  40 A in a state in which the reception electrode  34  is coupled. The fourth amount is less than the third amount. 
     The selector circuit  36 A of the storage amount detection device  20 C can switch whether or not to electrically couple at least two of the input terminals  41  to  44  of the input terminals  41  to  44  to the output terminal  40 A. The selector circuit  36 A can electrically couple the input terminals  43  and  44  to the output terminal  40 A, and can electrically disconnect the input terminals  41  and  43  from the output terminal  40 A. 
     As shown in  FIG.  29   , the selector circuit  36 A of the storage amount detection device  20 C switches whether or not to electrically couple at least two of the input terminals  41  to  44  of the input terminals  41  to  44  to the output terminal  40 A. The selector circuit  36 A electrically couples the input terminals  41  to  43  to the output terminal  40 A, and electrically disconnects the input terminal  44  from the output terminal  40 A. The selector circuit  36 A electrically disconnects only one of the input terminals  41  to  44  from the output terminal  40 A. 
     The selector circuit  36 A may electrically couple two input terminals  41  to  44  of the plurality of input terminals  41  to  44  to the output terminal  40 A, and may electrically disconnect the two remaining input terminals  41  to  44  from the output terminal  40 A. For example, the selector circuit  36 A can electrically couple the input terminals  43  and  44  to the output terminal  40 A and can electrically disconnect the remaining input terminals  41  and  42  from the output terminal  40 A. 
     Next, with reference to  FIG.  30   , error determination in the storage amount detection device  20 C according to the third modification example will be described.  FIG.  30    is a flowchart showing the error determination procedure in the detection circuit  63  of the storage amount detection device  20 C. In the storage amount detection device  20 C, the detection of the liquid level L is performed using the reception electrode disposed at a low position, and, sequentially, detection of the liquid level L is performed using the reception electrode disposed at a higher position. In the storage amount detection device  20 C, the detection of the liquid level L is performed in order of the reception electrode  34 , the reception electrode  33 , the reception electrode  32 , and the reception electrode  31 . 
     As shown in  FIG.  30   , first, in step S 71 , the detection circuit  63  determines whether or not the storage amount of the ink  2  is equal to or larger than the fourth amount based on the output from the output terminal  40 A in the state in which the reception electrode  34  is electrically coupled. When the storage amount is equal to or larger than the fourth amount, the process proceeds to step S 42 , and, when the storage amount is not equal to or larger than the fourth amount, it is determined that the storage amount is less than the fourth amount, and the process proceeds to step S 74 . 
     In step S 72 , the detection circuit  63  determines whether or not the storage amount of the ink  2  is less than the third amount based on the electric signal output from the output terminal  40 A in a state in which the reception electrodes  31  to  33  are coupled. In the state in which the reception electrodes  31  to  33  are electrically coupled to the output terminal  40 A, the reception electrode  34  is electrically disconnected from the output terminal  40 A. When the liquid level L is detected by the reception electrodes  31  to  33 , the detection circuit  63  determines that the storage amount is equal to or larger than the third amount. When the liquid level L is not detected by the reception electrodes  31  to  33 , the detection circuit  63  determines that the storage amount is less than the third amount. 
     When the storage amount is less than the third amount, the process proceeds to step S 73  and the detection circuit  63  determines that the detection of the storage amount is error. The case where the process proceeds to step S 73  is a case where it is determined that the storage amount is equal to or larger than the fourth amount and it is determined that the storage amount is less than the third amount, so that the detection of the storage amount is determined to be an error. When the storage amount is equal to or larger than the third amount, the detection circuit  63  ends the process here. 
     In step S 74 , the detection circuit  63  determines whether or not the storage amount of the ink  2  is equal to or larger than the third amount based on the electric signal output from the output terminal  40 A in the state in which the reception electrode  33  is coupled. In the state in which the reception electrode  33  is electrically coupled to the output terminal  40 A, the reception electrodes  31 ,  32 , and  34  are electrically disconnected from the output terminal  40 A. The detection circuit  63  proceeds to step S 75  when the storage amount is equal to or larger than the third amount, and proceeds to step S 77  when the storage amount is not equal to or larger than the third amount. 
     In step S 75 , the detection circuit  63  determines whether or not the storage amount of the ink  2  is less than the second amount based on the electric signal output from the output terminal  40 A in the state in which the reception electrodes  31  and  32  are coupled. In the state in which the reception electrodes  31  and  32  are electrically coupled to the output terminal  40 A, the reception electrodes  33  and  34  are electrically disconnected from the output terminal  40 A. When the liquid level L is detected by the reception electrodes  31  and  32 , the detection circuit  63  determines that the storage amount is equal to or larger than the second amount. When the liquid level L is not detected by the reception electrodes  31  and  32 , the detection circuit  63  determines that the storage amount is less than the second amount. 
     When the storage amount is less than the second amount, the detection circuit  63  proceeds to step S 76  and determines that the detection of the storage amount is error. The case where the process proceeds to step S 76  is a case where it is determined that the storage amount is equal to or larger than the third amount and the storage amount is less than the second amount, so that the detection of the storage amount is determined to be an error. When the storage amount is equal to or larger than the second amount, the detection circuit  63  ends the process here. 
     In step S 77 , the detection circuit  63  determines whether or not the storage amount of the ink  2  is equal to or larger than the second amount based on the electric signal output from the output terminal  40 A in the state in which the reception electrode  32  is coupled. In the state in which the reception electrode  32  is electrically coupled to the output terminal  40 A, the reception electrodes  31 ,  33 , and  34  are electrically disconnected from the output terminal  40 A. When the storage amount is equal to or larger than the second amount, the process proceeds to step S 78 , and, when the storage amount is not equal to or larger than the second amount, the detection circuit  63  ends the process here. 
     In step S 75 , the detection circuit  63  determines whether or not the storage amount of the ink  2  is less than the first amount based on the electric signal output from the output terminal  40 A in the state in which the reception electrode  31  is coupled. In the state in which the reception electrode  31  is electrically coupled to the output terminal  40 A, the reception electrodes  32  to  34  are electrically disconnected from the output terminal  40 A. When the liquid level L is detected by the reception electrode  31 , the detection circuit  63  determines that the storage amount is equal to or larger than the first amount. When the liquid level L is not detected by the reception electrode  31 , the detection circuit  63  determines that the storage amount is less than the first amount. 
     When the storage amount is less than the first amount, the detection circuit  63  proceeds to step S 79  and determines that the detected result of the storage amount is error. The case where the process proceeds to step S 78  is a case where it is determined that the storage amount is equal to or larger than the second amount and the storage amount is less than the first amount, so that the detection result of the storage amount is determined to be an error. When the storage amount is equal to or larger than the first amount, the detection circuit  63  ends the process here. 
     According to the storage amount detection device  20 C according to the third modification example, the liquid level L can be detected by electrically coupling the plurality of reception electrodes  31  to  34  to the output terminal  40 A by the selector circuit  36 A. The liquid level L is detected by coupling the plurality of reception electrodes  31  to  34  and it is determined whether or not the detection result of the storage amount is error. Therefore, it is not necessary to perform measurement of the liquid level L for each of the reception electrodes  31  to  34 . Therefore, the error determination can be rapidly performed, and the increase in the processing load in the detection circuit  63  is suppressed. 
     Next, a relationship between the output voltage V out  of the reception electrodes  31  to  33  and the detection result of the storage amount will be described with reference to  FIG.  31   .  FIG.  31    is a table showing the relationship between the output voltage V out  and the detection result.  FIG.  31    shows whether the detection result of the storage amount in the storage amount detection device  20 A including the three reception electrodes  31  to  33  is normal or error. As shown in  FIG.  31   , “H” indicates a case where the output voltage V out  is equal to or larger than the threshold value V th , and “L” indicates a case where the output voltage V out  is less than the threshold value V th , and “H/L” indicates a case of “H” or “L”. 
     In case  1 , all the output voltages V out  of the reception electrodes  31  to  33  are “H”, so that 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 larger than the first amount as the detection result of the storage amount. In case  2 , the output voltage V out  of the reception electrode  31  is “H”, the output voltage V out  of the reception electrode  32  is “L”, so that the detection circuit  63  determines that the detection result of the storage amount is error regardless of the output voltage V out  of the reception electrode  33 . In case  3 , the output voltage V out  of the reception electrode  31  is “H”, the output voltage V out  of the reception electrode  32  is “H”, and the output voltage V out  of the reception electrode  33  is “L”, so that the detection circuit  63  determines that the detection result of the storage amount is error. 
     In case  4 , the output voltage V out  of the reception electrode  31  is “L”, the output voltage V out  of the reception electrode  32  is “H/L”, and the output voltage V out  of the reception electrode  33  is “H”, so that the detection circuit  63  determines that the detection result of the storage amount is normal. In case  4 , when the output voltage V out  of the reception electrode  32  is “H”, the detection circuit  63  determines that the storage amount is equal to or larger than the second amount as the detection result of the storage amount. In case  4 , when the output voltage V out  of the reception electrode  32  is “L”, the detection circuit  63  determines that the storage amount is equal to or larger than the third amount as the detection result of the storage amount. In case  5 , the output voltage V out  of the reception electrode  31  is “L”, the output voltage V out  of the reception electrode  32  is “H”, the reception electrode  33  is “L”, so that the detection circuit.  63  determines that the detection result of the storage amount is error. In case  6 , the output voltage V out  of the reception electrode  31  is “L”, the output voltage V out  of the reception electrode  32  is “L”, and the output voltage V out  of the reception electrode  33  is “L”, so that 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 storage amount is less than the third amount as the detection result of the storage amount. 
     Next, with reference to  FIG.  32   , the relationship between the output voltages V out  of the reception electrodes  31  to  34  and the detection result of the storage amount will be described.  FIG.  32    is a table showing the relationship between the output voltage V out  and the detection result.  FIG.  32    shows whether the detection result of the storage amount in the storage amount detection device  20 C including the four reception electrodes  31  to  34  shown in  FIGS.  28  and  29    is normal or error. 
       FIG.  32    illustrates a case where two or more of the four reception electrodes  31  to  34  are electrically coupled to the output terminal  40 A to perform error determination.  FIG.  32    illustrates a part of the case where two or more reception electrodes  31  to  34  are coupled to the output terminal  40 A. In the case shown in  FIG.  32   , as shown in  FIG.  30   , measurement is performed first using the reception electrode  34  disposed at the low position, and, subsequently, measurement is performed using the reception electrode  33 , the reception electrode  32 , and the reception electrode  31  disposed at the higher positions. 
     In cases  1  to  3 , the storage amount detection device  20 C first performs measurement using the reception electrode  34 , and, thereafter, performs measurement using the reception electrodes  31  to  33 . In cases  1  to  3 , the detection circuit  63  performs the error determination based on an output in the state in which the reception electrodes  31  to  33  are simultaneously coupled to the output terminal  40 A. In case  1 , the output voltage V out  of the reception electrode  34  is “L” and the output voltages V out  of the reception electrodes  31  to  33  are “L”, so that 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 less than the fourth amount as the detection result of the storage amount. In case  2 , the output voltage V out  of the reception electrode  34  is “L” and the output voltages V out  of the reception electrodes  31  to  33  are “H”, so that the detection circuit  63  determines that the detection result of the storage amount is error. In case  3 , the output voltage V out  of the reception electrode  34  is “H” and the output voltages V out  of the reception electrodes  31  to  33  are “L”, so that 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 storage amount is equal to or larger than the fourth amount as the detection result of the storage amount. 
     In cases  4  to  6 , the storage amount detection device  20 C first performs the measurement using the reception electrodes  33  and  34 , and, thereafter, performs the measurement using the reception electrodes  31  and  32 . In the measurement using the reception electrodes  33  and  34 , the detection circuit  63  performs the error determination based on an output in a state in which the reception electrodes  33  and  34  are simultaneously coupled to the output terminal  40 A. In the measurement using the reception electrodes  31  and  32 , the detection circuit  63  performs the error determination based on an output in a state in which the reception electrodes  31  and  32  are simultaneously coupled to the output terminal  40 A. 
     In case  4 , the output voltages V out  of the reception electrodes  33  and  34  are “L” and the output voltages V out  of the reception electrodes  31  and  32  are “L”, so that 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 voltages V out  of the reception electrodes  33  and  34  are “L” and the output voltages V out  of the reception electrodes  31  and  32  are “H”, so that the detection circuit  63  determines that the detection result of the storage amount is error. In case  6 , the output voltages V out  of the reception electrodes  33  and  34  are “H” and the output voltages V out  of the reception electrodes  31  and  32  are “L”, so that 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 storage amount is equal to or larger than the third amount or equal to or larger than the fourth amount, as the detection result of the storage amount. 
     In cases  7  to  9 , the storage amount detection device  20 C first performs the measurement using the reception electrodes  32  to  34 , and, thereafter, performs the measurement using the reception electrode  31 . In the measurement using the reception electrodes  32  to  34 , the detection circuit  63  performs the error determination based on an output in a state in which the reception electrodes  32  to  34  are simultaneously coupled to the output terminal  40 A. 
     In case  7 , the output voltages V out  of the reception electrodes  32  to  34  are “L” and the output voltage V out  of the reception electrode  31  is “H”, so that the detection circuit  63  determines that the detection result of the storage amount is error. In case  8 , the output voltages V out  of the reception electrodes  32  to  34  are “L” and the output voltage V out  of the reception electrode  31  is “L”, so that 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 voltages V out  of the reception electrodes  32  to  34  are “H” and the output voltage V out  of the reception electrode  31  is “H/L”, so that the detection circuit  63  determines that the detection result of the storage amount is normal. In case  9 , when the output voltage V out  of the reception electrode  31  is “H”, the detection circuit  63  determines that the storage amount is equal to or larger than the first amount as the detection result of the storage amount. In case  9 , when the output voltage V out  of the reception electrode  31  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. 
     According to the storage amount detection device  20 C, it is possible to determine whether or not the detection result of the storage amount is error by using the output voltage V out  in the state in which the plurality of reception electrodes  31  to  34  are coupled to the output terminal  40 A. Therefore, it is not necessary to perform the measurement by individually switching the reception electrodes  31  to  34  for the reception electrodes  31  to  34 . According to the storage amount detection device  20 C, an increase in processing loads of the control section  60  is suppressed when performing an error determination. 
     The above-described embodiments merely show typical aspects of the present disclosure, and the present disclosure is not limited to the above-described embodiments, and various modifications and additions are possible in a scope that does not deviate from the gist of the present disclosure. 
     In the above-described embodiments, the storage amount detection device  20 A is configured to include three reception electrodes  31  to  33 , but the storage amount detection device  20 A is not limited to the configuration including the three reception electrodes  30 . The storage amount detection device  20 A may be configured to include one reception electrode  30 , may be configured to include two reception electrodes  30 , or may be configured to include four or more reception electrodes  30 . 
     In the above-described embodiments, the reception electrodes  31  to  33  are configured to be disposed at height positions different from each other, but a plurality of reception electrodes  31  to  33  may be configured to be disposed at the same height position. 
     In the above-described embodiments, the ink  2  is exemplified as an object stored in the storage sections  21 A to  21 D. However, the object stored in the storage sections  21 A to  21 D may be another liquid, a solid, or a gas. 
     In the above-described embodiments, the liquid discharge devices  1 A and  1 B in which the discharge section  4  and the storage sections  21 A to  21 D are mounted on the carriage  6  are described. However, the liquid discharge devices  1 A and  1 B are not limited thereto, and the discharge section  4  and the storage section  21 A may not be mounted on the carriage  6 . Further, the liquid discharge devices  1 A and  1 B are not limited to the serial-type ink jet printer, and may be other printing devices. 
     In the above-described embodiments, the storage sections  21 A to  21 D are exemplified as the ink cartridges of the liquid discharge devices  1 A and  1 B. However, the storage sections  21 A to  21 D may be ink tanks for storing the ink  2  used in other printing devices. The storage sections  21 A to  21 D may be mounted on an ink server that supplies the ink  2  to the printing device.