Patent Publication Number: US-10308034-B2

Title: Liquid container, liquid remaining amount detection circuit of liquid container, liquid remaining amount detection method, liquid container identification method, ink mounting unit, printer, and print system

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2016-081816, filed on Apr. 15, 2016, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a liquid container, a liquid remaining amount detection circuit of the liquid container, a liquid remaining amount detection method, a liquid container identification method, an ink mounting unit, a printer, and a print system. 
     BACKGROUND 
     There have been proposed various mechanisms for detecting and managing the remaining amount of ink in an ink cartridge containing an ink used in ink jet printers and the like. 
     A method of detecting the ink remaining amount may include, for example, a dot count method, an optical method, and the like. 
     The dot count method is a method of estimating an approximate ink remaining amount by counting an amount of ink consumed for printing, nozzle cleaning, and the like. This method has a function of warning by displaying on a display of a printer main body or by sounding a buzzer, when the ink remaining amount becomes small. 
     The optical method is a method of detecting presence or absence of ink by reflection of light which is contacted on a visible ink through a prism part obtained by partially machining a bottom of an ink cartridge into a prism shape. 
     There has also been proposed an ink cartridge having an IC chip or the like provided with an ink remaining amount detection function. 
     In order to detect the ink remaining amount in an ink cartridge, it is necessary to stabilize a level of ink in the ink cartridge. For example, when a printer or the like having an ink cartridge mounted thereon is installed in a tilted state, the remaining ink amount in the ink cartridge cannot be accurately detected. In particular, in the case of detecting a remaining amount of fuel in a fuel tank of a car or the like, when the car is traveling or stopped on a non-flat road surface, it is difficult to accurately detect the remaining amount of fuel in the fuel tank. 
     In addition, in the case of detecting a remaining amount of liquid such as an ink or a fuel, when a liquid container and its content is predetermined, it is possible to detect the remaining amount of the liquid by comparing a preset detection reference capacitance value corresponding to the container and the content with a level of the liquid. In this case, it is necessary to prepare a dedicated IC and a memory for storing the detection reference capacitance value and enabling it to be read out when necessary. However, if an IC or the like is prepared for each product, for example, for each ink cartridge, this may result in an increase in cost and time required for designing the product. 
     In addition, in the case of mounting an ink cartridge for color printing on an ink mounting unit or the like of a printer main body, it is necessary to mount ink cartridges prepared for different colors in respective predetermined positions in the ink mounting unit. 
     SUMMARY 
     The present disclosure provides some embodiments of a liquid container, a liquid remaining amount detection circuit of the liquid container, a liquid remaining amount detection method, a liquid container identification method, an ink mounting unit, a printer, and a print system, which are capable of detecting a remaining amount of liquid such as ink with high precision with a simple and inexpensive mechanism and identifying a liquid container such as an ink cartridge with a simple and inexpensive mechanism. 
     According to one embodiment of the present disclosure, there is provided a liquid container for accommodating a liquid, including: a plurality of detection electrodes mounted on the liquid container and connected to a detection circuit installed outside the liquid container. The plurality of detection electrodes detects a tilt of the liquid container. 
     According to another embodiment of the present disclosure, there is provided a detection circuit connected to a plurality of detection electrodes mounted on a liquid container, including: a capacitor having a reference capacitance; a capacitance/voltage conversion circuit configured to determine a voltage value corresponding to a level of a liquid in the liquid container by comparing capacitances detected by the plurality of detection electrodes with the reference capacitance; an analog/digital converter connected to an output of the capacitance/voltage conversion circuit and configured to convert the voltage value into a digital signal: and a microcontroller unit connected to an output of the analog/digital converter and configured to receive the digital signal as a value of the level of the liquid. The detection circuit detects a degree of tilt of the liquid container based on the capacitance detected by the plurality of detection electrodes, and detects a remaining amount of the liquid in the liquid container according to the detected degree of tilt. 
     According to another embodiment of the present disclosure, there is provided an ink mounting unit that mounts the above-described liquid container as an ink cartridge. 
     According to another embodiment of the present disclosure, there is provided a printer including: one or more above-described ink mounting units; one or more above-described detection circuits, each of which is connected to the plurality of detection electrodes installed in corresponding one of the one or more ink cartridges; and a printer main body control part configured to output a warning message or a warning sound to an output part in response to a remaining amount information of the liquid and an identification information of the liquid container transmitted from the one or more ink mounting units. 
     According to another embodiment of the present disclosure, there is provided a print system including: the above-described printer; and an external control device connected to the printer directly or via a network. The printer outputs the warning message or the warning sound to the external control device in response to the remaining amount information of the liquid and the identification information of the liquid container which are transmitted from the one or more ink mounting units. 
     According to another embodiment of the present disclosure, there is provided a method of detecting the remaining amount of a liquid in a liquid container, which is executed in a detection circuit connected to a plurality of detection electrodes mounted on the liquid container. The method includes: detecting, by the detection circuit, a level of the liquid in the liquid container using the plurality of detection electrodes; determining whether or not there is a difference in values detected using the plurality of detection electrodes; detecting, by the detection circuit, a degree of tilt of the liquid container based on the detected values when there is the difference in the detected values; and detecting, by the detection circuit, the remaining amount of the liquid in the liquid container according to the detected degree of tilt. 
     According to another embodiment of the present disclosure, there is provided a method of identifying a liquid container, which is executed in a detection circuit connected to a plurality of detection electrodes mounted on the liquid container. The method includes: detecting, by the detection circuit, an arrangement pattern of the plurality of detection electrodes in the liquid container; determining, by the detection circuit, whether or not the detected arrangement pattern matches a predetermined arrangement pattern; and determining, by the detection circuit, that the liquid container is not mounted in a predetermined position if the detected arrangement pattern does not match the predetermined arrangement pattern, and outputting a warning. 
     According to another embodiment of the present disclosure, there is provided a method of detecting the remaining amount of a liquid in a liquid container, which is executed in a detection circuit connected to a plurality of detection electrodes mounted on the liquid container. The method includes: performing, by the detection circuit, a calibration using the plurality of detection electrodes and setting and storing a reference capacitance value according to a state of the liquid container; detecting, by the detection circuit, a level of the liquid in the liquid container using the plurality of detection electrodes based on the reference capacitance value; determining, by the detection circuit, whether or not there is a difference in values detected using the plurality of detection electrodes; and determining, by the detection circuit, that the level of the liquid is low when there is the difference in the detected values, and outputting a warning. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a schematic perspective view showing an example of a liquid container having a capacitance type detection electrode.  FIG. 1B  is a schematic perspective view showing a state in which the liquid container shown in  FIG. 1A  is tilted in the direction of an arrow A 2 .  FIG. 1C  is a schematic perspective view showing a state in which the liquid container shown in  FIG. 1A  is tilted in the direction of an arrow A 1 . 
         FIGS. 2A to 2C  are schematic perspective views illustrating a liquid container according to a first embodiment.  FIG. 2A  illustrates an example of a liquid container having a plurality of detection electrodes formed on one side surface.  FIG. 2B  illustrates an example of a liquid container having a detection electrode formed on each of two opposing side surfaces.  FIG. 2C  illustrates an example of a liquid container having a plurality of detection electrodes formed on each of two opposing side surfaces. 
         FIGS. 3A to 3D  are schematic views illustrating a liquid container according to the first embodiment.  FIG. 3A  is a schematic perspective view illustrating a liquid container having a plurality of detection electrodes formed on the bottom surface.  FIG. 3B  is a schematic perspective view illustrating the liquid container shown in  FIG. 3A , which is seen from the bottom.  FIG. 3C  is a schematic side view showing an example in which the liquid container shown in  FIG. 3A  is tilted by an angle θ 1 .  FIG. 3D  is a schematic side view showing an example in which the liquid container shown in  FIG. 3A  is tilted by an angle θ 2 . 
         FIGS. 4A and 4B  are schematic views illustrating a liquid container according to the first embodiment.  FIG. 4A  is a schematic perspective view illustrating a liquid container having a plurality of detection electrodes formed on one side surface.  FIG. 4B  is a schematic side view illustrating the liquid container shown in  FIG. 4A , which is seen from the side surface on which the detection electrodes are formed. 
         FIG. 5  is a schematic side view showing an example in which a liquid container is tilted by an angle θ. 
         FIG. 6  is an explanatory view showing an example of a relationship (calculated value) among the number of detection electrodes, a hypotenuse, and an angle in a predetermined area (liquid amount) in the liquid container shown in  FIG. 5 . 
         FIGS. 7A and 7B  are schematic perspective views illustrating an example of a liquid container having an identification pattern.  FIG. 7A  illustrates an example of a liquid container having an identification pattern  50   1 .  FIG. 7B  illustrates an example of a liquid container having an identification pattern  50   2 . 
         FIGS. 8A to 8D  are schematic views illustrating an example of a liquid container having a projection for identifying the liquid container.  FIG. 8A  is a schematic side view showing an example of a liquid container in which the projection engages with a projection shape formed on a mounting part.  FIG. 8B  is a schematic side view showing an example of a liquid container in which the projection does not engage with a projection shape formed on a mounting part.  FIG. 8C  is a schematic perspective view showing an example in which the liquid container shown in  FIG. 8A  is mounted on the mounting part.  FIG. 8D  is a schematic perspective view showing an example in which the liquid container shown in  FIG. 8B  is mounted on the mounting part. 
         FIGS. 9A and 9B  are schematic perspective views illustrating a liquid container according to a second embodiment.  FIG. 9A  illustrates an example of a liquid container in which a maximum of three detection electrodes are formed on one side surface.  FIG. 9B  illustrates an example of the liquid container in which a maximum of two detection electrodes are formed on one side surface. 
         FIG. 10A  shows an example of the maximum of three detection electrodes formed in a liquid container.  FIG. 10B  shows another example of the maximum of three detection electrodes formed in a liquid container.  FIG. 10C  is an explanatory view illustrating an arrangement pattern of the maximum of three detection electrodes formed in a liquid container.  FIG. 10D  is an explanatory view illustrating an arrangement pattern of the maximum of two detection electrodes formed in a liquid container. 
         FIG. 11  is an explanatory view illustrating an arrangement pattern of the maximum of four detection electrodes and an arrangement pattern of four large and small detection electrodes. 
         FIG. 12  is a schematic side view showing an example of a liquid container configured to store a detection reference capacitance value in a built-in memory (ROM) of an IC. 
         FIG. 13  is a schematic side view showing an example of a liquid container configured to store a detection reference capacitance value in an external memory and to read and store it in a built-in memory (RAM) of an IC when necessary. 
         FIG. 14  is a schematic side view showing an example of a liquid container configured to store a detection reference capacitance value in a built-in memory (flash memory) of an IC. 
         FIG. 15  is an explanatory view showing an example of setting of a detection reference capacitance value for a liquid container according to a third embodiment. 
         FIG. 16  is an explanatory view showing an example of detection of the liquid remaining amount using a detection reference capacitance value for the liquid container according to the third embodiment. 
         FIG. 17  is a schematic side view showing an example in which the liquid container according to the first and third embodiments is applied to a fuel tank of a car. 
         FIGS. 18A and 18B  illustrate examples of detection of the liquid remaining amount in a state where a liquid surface in the liquid container according to the first and third embodiments is ruffled.  FIG. 18A  shows an example of a liquid level L 51 .  FIG. 18B  shows an example of a liquid level L 52 . 
         FIG. 19  is a schematic block diagram illustrating a block configuration of a detection circuit applicable to the first to third embodiments. 
         FIG. 20  is a schematic block diagram illustrating a first aspect of a print system applicable to the first to third embodiments. 
         FIG. 21  is a schematic block diagram illustrating a second aspect of the print system applicable to the first to third embodiments. 
         FIG. 22  is a schematic block diagram illustrating a third aspect of the print system applicable to the first to third embodiments. 
         FIG. 23  is a schematic block diagram illustrating a fourth aspect of the print system applicable to the first to third embodiments. 
         FIG. 24  is a schematic block diagram illustrating a fifth aspect of the print system applicable to the first to third embodiments. 
         FIG. 25  is a flowchart schematically illustrating a process sequence of a detection method of a liquid remaining amount in the liquid container according to the first embodiment. 
         FIG. 26  is a flowchart schematically illustrating a process sequence of identifying the liquid container according to the second embodiment. 
         FIG. 27  is a flowchart schematically illustrating a process sequence of a detection method of a liquid remaining amount in the liquid container according to the third embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure will now be described in detail with reference to the drawings. Throughout the drawings, the same or similar elements are denoted by the same or similar reference numerals. It is however noted that the drawings are just schematic and relationships between thickness and planar dimension of elements, thickness ratios of various layers and so on may be unrealistic. Accordingly, detailed thickness and dimensions should be determined in consideration of the following description. In addition, it is to be understood that the figures include different dimensional relationships and ratios. 
     The following embodiments are provided to illustrate devices and methods to embody the technical ideas of the present disclosure and are not limited to materials, forms, structures, arrangements and so on of elements detailed herein. The embodiments of the present disclosure may be modified in different ways without departing from the scope of the present disclosure defined in the claims. 
     First Embodiment 
     (Example of Liquid Container Having Detection Electrode) 
       FIG. 1A  schematically shows an example of a liquid container  20  having a capacitance type detection electrode  40  according to a first embodiment. As illustrated in  FIG. 1A , the liquid container  20  such as an ink cartridge includes one capacitance type detection electrode  40  mounted on one surface (for example, one side surface) of the liquid container  20 . The detection electrode  40  is connected to a detection circuit  30  (IC chip) (see  FIGS. 19 to 24 ) installed outside the liquid container  20 . The detection electrode  40  is vertically elongated from the vicinity of the bottom of the liquid container  20  (near the height of the minimum level of liquid  29  such as ink) to the vicinity of the top of the liquid container  20  (near the height of the maximum level of the liquid  29 ). The liquid  29  may include an aqueous solution, mixed water, and the like. The detection electrode  40  may be laid on the outer side or inner side surface of the liquid container  20 , or embedded in the outer wall of the liquid container  20 . When the detection electrode  40  is laid on the outer side surface of the liquid container  20  or is embedded in the outer wall, the detection electrode  40  may be installed with a predetermined distance (that is to say, a minimum distance required for the detection electrode  40  to detect the existence of the liquid  29 , for example, about 1 to 2 mm) from the liquid  29  so as to prevent the detection electrode  40  from making direct contact with the liquid  29 . 
     The detection electrode  40  is an electrode used to detect contact or non-contact of the liquid  29  with the detection electrode  40  (that is to say, presence or absence of the liquid  29 ) based on a change in capacitance. The detection circuit  30  has a reference value (reference capacitance value) serving as a reference for calibration and compares a capacitance sensed by the detection electrode  40  with the reference capacitance value to detect a level of the liquid  29  (that is to say, a liquid remaining amount) in the liquid container  20 . Instead of the capacitance type detection electrode, a pressure-sensitive resistive film type detection electrode may be adopted as the detection electrode  40 . 
     Here, when the liquid container  20  is stably installed as illustrated in  FIG. 1A , the level (the height of surface) of the liquid  29  in the liquid container  20  is also stable. Thus, it is possible to detect a change in capacitance by a rate exceeding a sampling (detection) cycle and recognize the detection result as a variation in the level of the liquid  29 . 
     In contrast, in a state where the liquid container  20  is shaken or tilted, for example, when the liquid container  20  is tilted in the direction of an arrow A 2  as illustrated in  FIG. 1B  or when the liquid container  20  is tilted in the direction of an arrow A 1  as illustrated in  FIG. 1C , the level of the liquid  29  becomes unstable and biased. In this case, it is difficult for the detection electrode  40  to accurately detect the amount (remaining amount) of the liquid  29 . 
     (Configuration Example of Liquid Container Having Detection Electrode for Tilt Detection) 
     The liquid container  20  according to the first embodiment is schematically illustrated in  FIGS. 2A to 2C . 
       FIG. 2A  illustrates a liquid container  20  having a plurality of (two in the illustrated example) detection electrodes  40   1  and  40   2  installed in one side surface of the liquid container  20  (on the outer side or inner side surface of the liquid container  20  or inside of the outer wall of the liquid container  20 ). Since the plurality of detection electrodes  40   1  and  40   2  is installed in this manner, even when the liquid container  20  is tilted, a degree of tilt (tilt angle) of the liquid container  20  can be detected by detecting a difference between the widths W 1  and W 2  of non-detection portions in the respective detection electrodes  40   1  and  40   2  and the level (remaining amount) of the liquid  29  can be accurately detected in consideration of the degree of tilt of the liquid container  20 . As such, the liquid container  20  having a plurality of (two or more) detection electrodes  40   1  and  40   2  installed in one side surface of the liquid container  20  can be effectively used to detect a change occurring between the plurality of (two or more) detection electrodes  40   1  and  40   2 . 
       FIG. 2B  illustrates a liquid container  20  having detection electrodes  40   1  and  40   2  installed in two opposing side surfaces of the liquid container  20  (one detection electrode for each of the two opposing side surfaces in the example of  FIG. 2B ). As illustrated in  FIG. 2B , when a change in the level of the liquid  29  is uniform with respect to a wall surface (in the direction of an arrow A 3  in the example of  FIG. 2B ), it is effective to install the detection electrodes  40   1  and  40   2  in the two opposing side surfaces of the liquid container  20  as described above. 
       FIG. 2C  illustrates a liquid container  20  having a plurality of detection electrodes  40   1 ,  40   2 ,  40   3 , and  40   4  installed in two opposing side surfaces of the liquid container  20  (two detection electrodes for each of the two opposing side surfaces in the example of  FIG. 2C ). Since the plurality of detection electrodes  40   1  and  40   2  and the plurality of detection electrodes  40   3  and  40   4  are respectively formed on two opposing side surfaces of the liquid container  20 , it is possible to accurately detect the level (remaining amount) of the liquid  29  in response to the direction and degree of tilt of the liquid container  20 . For example, it is possible to accurately detect the level (remaining amount) of the liquid  29  in a case where the liquid container  20  is tilted in the direction of the arrow A 3  in  FIG. 2B , in a case where the liquid container  20  is tilted in the direction of an arrow A 4  in  FIG. 2C , and the like. In addition, the plurality of detection electrodes  40  installed in the liquid container  20  as illustrated in  FIGS. 2A to 2C  can be used in common for identification of the liquid container  20 . Details of the identification of the liquid container  20  will be described later in a second embodiment. 
       FIGS. 3A to 3D  illustrate a liquid container  20  having a plurality of (n) detection electrodes  40   1 ,  40   2 , . . . ,  40   n  (n is an integer equal to or greater than 1) installed at predetermined intervals (for example, equal intervals) therebetween in the bottom surface of the liquid container  20  according to the first embodiment. By forming a plurality of (n) detection electrodes  40   1 ,  40   2 , . . . ,  40   n  in the bottom surface of the liquid container  20  as illustrated in  FIGS. 3A to 3D , even when the amount of shaking or tilt of the liquid container  20  is relatively large (even when the liquid container  20  is significantly shaken or tilted), it is possible to detect the degree of tilt (tilt angle) of the liquid container  20  with higher accuracy. As illustrated in  FIGS. 3C and 3D , the degree of tilt (tilt angle) of the liquid container  20  can be detected with high accuracy based on which of the plurality of detection electrodes  40   1 ,  40   2 , . . . ,  40   n  installed in the bottom surface of the liquid container  20  detects the presence or absence of the liquid container  20 .  FIG. 3C  shows an example in which the liquid container  20  is tilted by an angle θ 1  and  FIG. 3D  shows an example in which the liquid container  20  is tilted by an angle θ 2 . As illustrated in  FIGS. 4A and 4B , even when a plurality of (three in the example of  FIGS. 4A and 4B ) detection electrodes  40   1 ,  40   2  and  40   3  is installed at predetermined intervals (for example, at equal intervals) in one side surface of the liquid container  20 , it is possible to detect the degree of tilt (tilt angle) of the liquid container  20  with high accuracy. 
       FIG. 5  illustrates an example in which the liquid container  20  according to the first embodiment is tilted by an angle θ. As illustrated in  FIG. 5 , when an area α (the amount of the liquid  29 ) is fixed, a right triangle having the area α and sides x, y, and c is formed. Using this right triangle, the area α, the sides x, y, and c, a tilt height z of the liquid container  20 , and a tilt angle θ of the liquid container  20  can be obtained from the following equations (1) to (8).
 
α=( x·y )/2  (1)
 
 y= 2 a/x   (2)
 
 c =√( x   2   +y   2 )  (3)
 
 c =√( x   2 +(2α/ x ) 2 )  (4)
 
 z= 2α/ c   (5)
 
 z= 2α/√( x   2 +(2α/ x ) 2 )  (6)
 
θ=sin −1 (2α/( x ·√( x   2 +(2α/ x ) 2 )  (7)
 
 z=x  sin θ  (8)
 
     The calculation accuracy of the tilt angle θ of the liquid container  20  is improved in proportion to the number of detection electrodes  40   1 ,  40   2 , . . . ,  40   n  installed in the liquid container  20 . 
     When the detection circuit  30  is equipped in an IC chip, reference values (calculated values) illustrated in  FIG. 6  may be prepared in advance and stored in the detection circuit  30  so that they can be read out when necessary. This makes it possible to effectively reduce the circuit scale of the IC chip.  FIG. 6  shows an example of a relationship (calculated values) among the number of detection electrodes  40   1 ,  40   2 , . . . ,  40   n  that detect the liquid  29  forming a predetermined area α (for example, 5 cm 2 ), a hypotenuse c, and a tilt angle θ in the liquid container  20  illustrated in  FIG. 5 . For example, when the number of detection electrodes  40  that detected the liquid  29  is six, the hypotenuse c is 12 cm and the tilt angle θ of the liquid container  20  is 3.97 degree. When the number of detection electrodes  40  that detect the liquid  29  is one, the hypotenuse c is 2 cm and the tilt angle θ of the liquid container  20  is 68.20 degree. 
     As described above, according to the first embodiment, with a simple and inexpensive mechanism in which the detection electrodes  40  ( 40   1 ,  40   2 , . . . ,  40   n ) for tilt detection are installed in the liquid container  20 , the tilt of the liquid container  20  can be detected with high accuracy. Further, the detection circuit (IC chip)  30  can detect the level (remaining amount) of the liquid  29  in the liquid container  20  in response to the detected tilt of the liquid container  20  with high accuracy. 
     Second Embodiment 
     (Identification of Liquid Container) 
     For example, when an ink cartridge (liquid container)  20  for color printing is mounted on a mounting unit or the like of a printer main body, it is necessary to correctly mount the ink cartridges  20  prepared for different ink colors in respective predetermined positions in the mounting unit. Particularly, in many cases of mounting the ink cartridges  20  for color printing, the ink cartridges  20  being the same in shape and size but different in colors (for example, four colors, six colors, and the like) are arranged adjacent to each other. Even though the ink cartridges  20  have the common role and basic structure, it is necessary to identify the type of each of the ink cartridges  20  according to its contents (color or kind of ink) and mount each of the ink cartridges  20  on a correct mounting part. 
     An example of a liquid container  20  having an identification pattern (picture symbol)  50   1  or  50   2  of the liquid container  20  is schematically illustrated in  FIGS. 7A and 7B . For example, the detection circuit (IC chip)  30  reads the identification pattern  50   1  or  50   2  by means of, for example, a reading sensor (not shown). If the identification pattern  50   1  is provided (printed) in the liquid container  20 , the detection circuit  30  identifies the container as a yellow ink cartridge  20 , for example. If the identification pattern  50   2  is provided (printed) in the liquid container  20 , the detection circuit  30  identifies the container as a blue ink cartridge  20 , for example. As a result, it can be determined whether or not the ink cartridge  20  is mounted on an incorrect portion. 
     An example of a liquid container  20  having a projection  21   a  or  21   b  for identifying the liquid container  20  is schematically illustrated in  FIGS. 8A to 8D .  FIG. 8A  schematically shows an example of the liquid container  20  provided with the projection  21   a  which engages with the shape of a projection  200   a  formed on a mounting part and  FIG. 8B  schematically shows an example of the liquid container  20  provided with the projection  200   b  which does not engage with the shape of a projection  200   b  formed on a mounting part. As illustrated in  FIG. 8C , the liquid container  20  having the projection  21   a  can be mounted on the mounting part because the projection  21   a  engages with the shape of the projection  200   a , but as illustrated in  FIG. 8D , the liquid container  20  having the projection  20   b  cannot be mounted on the mounting part because the projection  20   b  does not engage with the shape of the projection  200   b . Thus, it is possible to mount the ink cartridge  20  in a correct place. 
     (Configuration Example of Liquid Container Having Detection Electrode for Container Identification) 
       FIGS. 9A and 9B  schematically illustrate examples of a liquid container  20  using the detection electrodes  40  ( 40   1 ,  40   2 , . . . ,  40   n ) in common for tilt detection as in the first embodiment and for container identification.  FIG. 9A  shows an example of the liquid container  20  having the maximum of three detection electrodes  40   1 ,  40   2  and  40   3  installed in one side surface of the liquid container  20 , and  FIG. 9B  shows an example of the liquid container  20  having the maximum of two detection electrodes  40   1  and  40   2  installed in one side surface of the liquid container  20 .  FIGS. 10A to 10D  shows various examples of the detection electrodes  40  ( 40   1 ,  40   2 , . . . ,  40   n ) for container identification. 
     For example, for the liquid container  20  in which up to three detection electrodes  40   1 ,  40   2  and  40   3  can be installed, there may be an arrangement pattern illustrated in  FIG. 10A  in which two detection electrodes  40   1  and  40   3  are installed but the detection electrode  40   2  is not installed in the liquid container  20 . In addition, there may be an arrangement pattern illustrated in  FIG. 10B  in which two detection electrodes  40   2  and  40   3  are installed but the detection electrode  40   1  is not installed in the liquid container  20 . As such, using the combination of arrangement patterns of the detection electrodes  40   1 ,  40   2 , and  40   3 , as illustrated in  FIG. 10C , it is possible to identify liquid containers  20  of eight types which are exponential multiples of 2. 
     Further, as illustrated in  FIG. 10D , for the liquid container  20  in which up to two detection electrodes  40   1  and  40   2  can be formed, liquid containers  20  of four types which are exponential multiples of 2 can be identified. The arrangement pattern  8  “000” illustrated in  FIG. 10C  and the arrangement pattern  4  “00” illustrated in  FIG. 10D  can be applied to a case where the detection electrodes  40  are used for detection of level and tilt of the liquid  29  (the first embodiment) but does not used for identification of the liquid container  20  (the second embodiment). 
       FIG. 11  illustrates an arrangement pattern based on the presence or absence of up to four detection electrodes  40  (see upper portion in  FIG. 11 ) and an arrangement pattern of four large and small detection electrodes  40  (see lower portion in  FIG. 11 ). As illustrated in  FIG. 11 , four ink colors of “red”, “yellow”, “blue” and “black” are allocated to each of the arrangement patterns. 
     As described above, according to the second embodiment, the detection electrodes  40  ( 40   1 ,  40   2 , . . . ,  40   n ) used for tilt detection in the first embodiment can also be used for container identification. Therefore, it is possible to identify the liquid containers  20  without printing arrangement patterns (picture symbols)  50  on the liquid containers  20  or without forming individual projections  21   a  and  21   b  in the liquid containers  20 , which contributes to cost reduction. 
     Third Embodiment 
     (Built-in of Reference Capacitance for Calibration) 
     As described in the first embodiment, in the case of detecting the remaining amount of the liquid  29  such as ink or fuel, when the contents of the liquid  29  and the shape and size of the liquid container  20  containing the liquid  29  are predetermined, a remaining amount detection reference capacitance value (calculated value) for the container or contents may be prepared in advance to detect the remaining amount of the liquid by comparing the level of the liquid with the reference capacitance value. In this case, it is necessary to prepare a dedicated IC and a memory for storing the reference capacitance value and enabling it to be read out when necessary. However, if an IC or the like is prepared for each product (for example, for each liquid container), this may result in an increase in cost and time required for designing the product. 
     In order to avoid this, if a setting value of a factor is not predetermined, it is effective to set the factor in a later time. In this case, a setting value as a reference may be extracted under a state where the container is installed in a set such as a mounting unit for trial production and the like, and stored in a memory of an IC. As a specific example of a storage for the setting value, a built-in memory (for example, a flash memory) or an external memory (for example, an EEPROM) may be used. However, using an external memory or an IC having a built-in flash memory may incur additional costs. 
       FIG. 12  shows an example of a liquid container  20  configured to store a reference capacitance value in a built-in memory (ROM  91 ) of an IC  90 .  FIG. 13  shows an example of a liquid container  20  configured to store a reference capacitance value in an external memory (EEPROM  95 ) and read and store the same in a built-in memory (RAM  92 ) of an IC  90  when necessary.  FIG. 14  shows an example of a liquid container  20  configured to store a reference capacitance value in an internal memory (flash memory  93 ) of an IC  90 . In general, the ROM  91 , the RAM  92 , and the flash memory  93  establish a size relationship of ROM  91 &lt;RAM  92 &lt;flash memory  93 . 
     In order to eliminate storage elements such as memories and achieve further cost reduction, a reference capacitance setting value is extracted by a calibration at a system start-up time and the like, and the extracted reference capacitance setting value is stored so as to be read out when necessary. 
       FIG. 15  schematically shows an example of a reference capacitance value set for the liquid container  20  according to the third embodiment. 
     In a configuration requiring a calibration, when detection is started under a state in which the liquid  29  fully fills a tank (the liquid  29  is the maximum amount) as illustrated in the left side of  FIG. 15  or a state in which the current remaining amount of the liquid  29  is considered to fully fill a tank (the current remaining amount of the liquid  29  is considered to be the maximum amount), it is possible to carry out the calibration in the actual state. In some embodiments, a reference capacitance value C 31  corresponding to a state (level L 2 ) detected by the detection electrode  40   1  or a capacitance value close thereto may be stored as a reference value in an external memory or the like. In this case, the level of the liquid  29  is changed in a way of going down from a full state. 
     However, as illustrated in the right side of  FIG. 15 , in the case of restarting detection of the remaining amount of the liquid  29  in the middle of the process, i.e., in the case where it is necessary to recognize a previous state (a state before the restart, for example, the level L 1 ) and restart detection, a structure such as a memory circuit for storing the previous state is required. In this case, a state in which the level of the liquid  29  in the liquid container  20  is lowered with respect to the full state (a previously detected capacitance value C 32  which corresponds to the level L 1  previously detected by the detection electrode  40   3 ) is stored and this information is inherited when restarting the detection (at a next power-on time). 
     In the third embodiment, the reference capacitance value C 31  as described above is fixed and stored in advance (for example, at the time of factory shipment and the like), and the previously detected capacitance value C 32  corresponding to the previously detected level L 1  is stored at each time when the remaining amount detection process is performed (for example, when a power supply is turned off after detection) in the RAM  92 , flash memory  93 , and the like of the built-in IC  90 . W 1 th this configuration, the remaining amount detection, i.e., determining whether or not the level of the liquid  29  has fallen below the reference capacitance value, can be realized without using an external capacitor or a memory circuit. The reference capacitance value to be set for all environments where the value is commonly used is checked in advance and the minimum required capacitance value is stored as a reference value in the built-in IC  90 . The storage of the reference capacitance value in the built-in IC  90  may be achieved by means of any methods including incorporation into an LSI, using an SiP (System in Package) which integrates an LSI and storage means of capacitances (the reference capacitance value C 31  and the previously-detected capacitance value C 32 ) in one IC package, writing digitized reference capacitance values into ROM, and the like. 
       FIG. 16  schematically illustrates an example of detection of the remaining amount of the liquid  29  using a reference capacitance value for the liquid container  20  according to the third embodiment. 
     A reference capacitance value corresponding to the level in the vicinity of the detection electrodes  40   1  and  40   2  is embedded as a set reference in the IC  90 . At the time of detection, a detected capacitance value is compared with the reference capacitance value to determine the status of the level of the liquid  29 . When the detected capacitance value is equal to or smaller than the reference capacitance value, it may be determined that the level of the liquid  29  is lower than the positions of the detection electrodes  40   1  and  40   2 . 
     In  FIG. 16 , when a calibration is performed on a level range L 3 - 1 , the same capacitance value is detected regardless of a change in the level until the level reaches the detection electrode  40   2 . Thereafter, when a calibration is performed on a level range L 3 - 2 , a change in capacitance value in the width of the detection electrode  40   2  is detected. Further, when a calibration is performed on a level range L 3 - 3 , since a difference occurs between detection capacitance values in the detection electrode  40   1  and in the detection electrode  40   2 , a fall of the liquid level below the detection electrode  40   2  can be detected. Here, the structure of the liquid container  20  is set such that the liquid level exists in the width of the lowest detection electrode  40   1 . 
     As described above, according to the third embodiment, even in the case where the detection is temporarily stopped in the middle of the process and then is restarted, it is possible to detect the remaining amount of the liquid with high accuracy by comparing the liquid level with the reference capacitance value C 31 , without using a dedicated IC or a memory for storing the reference capacitance value C 31  and enabling it to be read out when necessary. 
     (Application Example to Fuel Tank) 
       FIG. 17  schematically shows an application example of the liquid container  20  according to the embodiments to a fuel tank of a car or the like. A fuel tank of a car or the like has various shapes according to the body shape of the car. The fuel tank (liquid container  20 ) as illustrated in  FIG. 17  includes detection electrodes  40   1-1 ,  40   1-2 ,  40   1-3  and  40   1-4  for detecting the remaining amount of the fuel (liquid)  29  within a range from a full level to a liquid level L 4 , and detection electrodes  40   2-1 ,  40   2-2 ,  40   2-3  and  40   2-4  for detecting the remaining amount of the fuel  29  within a range from the liquid level L 4  to an empty level. Accordingly, it is possible to detect the remaining amount of the fuel  29  with high accuracy even in a case where the liquid container  20  has a distorted structure. 
       FIGS. 18A and 18B  illustrate examples of detection of the liquid remaining amount in a state in which a liquid surface  29   a  in the liquid container  20  according to the embodiment is ruffled. Especially in the case of the fuel tank of the car, when the car is traveling, the liquid surface  29   a  of the fuel  29  is ruffled due to the vibration of the car. In addition, even when the car is stopped, since the parking place is not limited to a flat road surface, there are some cases where the liquid surface  29   a  is also not flattened. As illustrated in  FIGS. 18A and 18B , since the liquid container  20  according to the embodiment includes a plurality of detection electrodes  40   1 ,  40   2 , . . . ,  40   6  and  40   7 , it is possible to detect the liquid level L 51  as shown in  FIG. 18A  by comparing detected capacitance values of the detection electrodes  40   2  and  40   3  and detect the liquid level L 52  as shown in  FIG. 18B  by comparing detected capacitance values of the detection electrodes  40   4  and  40   5 . 
     (Detection Circuit) 
       FIG. 19  is a schematic block configuration view of the detection circuit  30  applicable to the first to third embodiments. For the sake of simplicity of explanation, an example using two electrodes of the detection electrode  40   1  and the detection electrode  40   2  are shown in  FIG. 19 . 
     The detection circuit  30  includes: a switch group including a plurality of switches SW- 1 , SW- 2 , and SW- 3 , which selectively switches and connects one of the detection electrode  40   1  and the detection electrode  40   2  and a capacitor having a reference capacitance C 1  to a capacitance/voltage conversion circuit  32 ; the capacitance/voltage conversion circuit  32  connected to the output side of the switch group; an analog/digital (AD) converter  33  connected to the output of the capacitance/voltage conversion circuit  32 ; an analog front end (AFE)  34  connected to the detection electrode  40   1  and the detection electrode  40   2 ; and a micro controller unit (MCU)  35  connected to the output of the A/D converter  33  and the output of the AFE  34 . The capacitance/voltage conversion circuit  32  receives the capacitance C 1  as the reference capacitance value and one of the detection electrode  40   1  and the detection electrode  40   2 , which is selectively connected by the switch group, as measurement electrodes, and detects a displacement based on a comparison of a capacitance C 2  of a capacitor connected to an inverting input of an operational amplifier OP and a capacitance C 3  of a capacitor connected between the inverting input and an output of the operational amplifier OP. The output of the capacitance/voltage conversion circuit  32  is converted into a digital signal by the A/D converter  33 , supplied to the MCU  35 , and then detected as a value of the level (that is, the ink remaining amount) of the ink  29  in the liquid container  20 . 
     The detection circuit  30  configured as above can function as the detection circuit  30  for detecting the remaining amount as described in the first embodiment and the third embodiment. 
     The AFE  34  connected to the detection electrode  40   1  and the detection electrode  40   2  detects the presence or absence (of the electrical connection) of the detection electrode  40   1  and the detection electrode  40   2  and supplies a result of the detection to the MCU  35 . By detecting the presence or absence of the detection electrode  40   1  and the detection electrode  40   2 , the detection circuit  30  can function, for example, as the detection circuit  30  for identifying the liquid container  20  as described in the second embodiment. 
     (Application Example to Print System) 
     (Print System (First Aspect)) 
       FIG. 20  schematically illustrates a block configuration of a first aspect of a print system applicable to the first to third embodiments. 
     As illustrated in  FIG. 20 , the print system of the first aspect includes a printer main body  100  and an external control device  200  which are connected with each other directly or via a wired/wireless network  300  such as a cloud network. 
     The printer main body  100  includes an ink mounting unit  10 , a printer main body control part  101 , an input part  102 , an output part  103 , a storage part  104 , and an I/F part  109 . 
     The printer main body control part  101  transmits a setting value and a threshold value input from the input part  102  to the ink mounting unit  10  or stores them in the storage part  104 . In addition, upon receiving ink shortage information or the like transmitted from the ink mounting unit  10 , in response to the information, the printer main body control part  101  may output a warning message, a warning sound or the like to the output part  103  or notify the external control device  200  of the information via the L/F part  109 . 
     The ink mounting unit  10  is configured to mount, for example, up to N (N is an integer equal to or greater than 1) ink cartridges (liquid containers)  20  ( 20 - 1 ,  20 - 2 , . . . ,  20 -N). The ink mounting unit  10  includes N detection circuits  30  ( 30 - 1 ,  30 - 2 , . . . ,  30 -N), each of which is connected to the detection electrodes  40   1 , . . . ,  40   N  of corresponding one of the N ink cartridges  20 , and an I/F part  39  for controlling communication between each of the detection circuits  30  and the printer main body control part  101 . The ink mounting unit  10  can appropriately mount the ink cartridges (liquid containers)  20  according to the first to third embodiments. Each of the detection circuits  30  ( 30 - 1 ,  30 - 2 , . . . ,  30 -N) has an internal storage part  14  for storing a reference capacitance value for detection and a previous detected capacitance value. For example, the storage part  14  may be configured as an SiP (System in Package) that integrates an LSI and storage means for capacitances in one IC package. 
     In the print system according to the first aspect, since the detection circuits  30  are connected to the respective N ink cartridges  20  arranged for different ink colors, it is advantageous in terms of processing time over a detection operation of the plurality of ink cartridges  20  by using a single detection circuit  30 . 
     The external control device  200  may be configured with, for example, a personal computer, a tablet computer, a smartphone, or the like. The external control device  200  includes a control part  201 , an input part  202 , an output part  203 , a storage part  204 , and an I/F part  209 . The control part  201  transmits a setting value and a threshold value input from the input part  202  to the printer main body  100  or stores them in the storage part  204 . In addition, upon receiving ink shortage information or identification information of the ink cartridges  20  transmitted from the printer main body  100 , in response to the information, the control part  201  may output a warning message, a warning sound or the like to the output part  203 . 
     (Print System (Second Aspect)) 
       FIG. 21  schematically illustrates a block configuration of a second aspect of the print system applicable to the first to third embodiments. 
     As illustrated in  FIG. 21 , in the print system according to the second aspect, the ink mounting unit  10  includes a single detection circuit  30  corresponding to the N ink cartridges  20 - 1 ,  20 - 2 , . . . ,  20 -N, instead of the N detection circuits  30 - 1 ,  30 - 2 , . . . ,  30 -N corresponding respectively to the N ink cartridges  20 - 1 ,  20 - 2 , . . . ,  20 -N. The remaining parts have the same configurations as those in the print system according to the first aspect. 
     In the print system according to the second aspect, since the detection operation of the plurality of ink cartridges  20  is performed by the single detection circuit  30 , it is possible to reduce the costs for the detection circuit  30 . 
     (Print System (Third Aspect)) 
       FIG. 22  schematically illustrates a block configuration of a third aspect of the print system applicable to the first to third embodiments. 
     As illustrated in  FIG. 22 , in the print system according to the third aspect, instead of the ink mounting unit  10 , the printer main body  100  includes a single detection circuit  30  corresponding to the N ink cartridges  20 - 1 ,  20 - 2 , . . . ,  20 -N. The remaining parts have the same configurations as those in the print system according to the second aspect. Although not shown, the detection circuit  30  may include the storage part  14 , separately from the storage part  104  included in the printer main body  100 . 
     In the print system according to the third aspect, since the printer main body  100  includes the single detection circuit  30  that performs the detection operation of the plurality of ink cartridges  20 , it is possible to reduce the costs for the ink mounting unit  10 . 
     (Print System (Fourth Aspect)) 
       FIG. 23  schematically illustrates a block configuration of a fourth aspect of the print system applicable to the first to third embodiments. 
     As illustrated in  FIG. 23 , in the print system according to the fourth aspect, instead of the ink mounting unit  10 , the printer main body  100  includes the N detection circuits  30 - 1 ,  30 - 2 , . . . ,  30 -N corresponding respectively to the N ink cartridges  20 - 1 ,  20 - 2 , . . . ,  20 -N. The remaining parts have the same configurations as those in the print system according to the first aspect. Although not shown, each of the detection circuits  30 - 1 ,  30 - 2 , . . . ,  30 -N may include the storage part  14 , separately from the storage part  104  included in the printer main body  100 . 
     In the print system according to the fourth aspect, since the printer main body  100  includes the N detection circuits  30 - 1 ,  30 - 2 , . . . ,  30 -N that perform the respective detection operations of the plurality of ink cartridges  20 , it is possible to reduce the costs for the ink mounting unit  10 . In addition, it is more advantageous in terms of processing time than performing the detection operations of the plurality of ink cartridges  20  by using a single detection circuit  30 . 
     (Print System (Fifth Aspect)) 
       FIG. 24  schematically illustrates a block configuration of a fifth aspect of the print system applicable to the first to third embodiments. 
     As illustrated in  FIG. 24 , in the print system according to the fifth aspect, instead of the ink mounting unit  10  and the printer main body  100 , the external control device  200  includes the single detection circuit  30  corresponding to the N ink cartridges  20 - 1 ,  20 - 2 , . . . ,  20 -N. The remaining parts have the same configurations as those in the print system according to the first to fourth aspects. Although not shown, the detection circuit  30  in the external control device  200  may include the storage part  14 , separately from the storage part  204  included in the external control device  200 . 
     In the print system according to the fifth aspect, since the external control device  200  includes the single detection circuit  30  that performs the detection operation of the plurality of ink cartridges  20 , it is possible to reduce the costs for the ink mounting unit  10  and the printer main body  100 . 
     (Method of Detecting Liquid Remaining Amount in Liquid Container According to First Embodiment) 
       FIG. 25  schematically illustrates a process sequence of a method of detecting the liquid remaining amount in the liquid container  20  according to the first embodiment. 
     For example, when the printer main body  100  or the like is powered on (or the engine of a car is started), the process is started (step S 100 ). 
     First, in step S 101 , a calibration is performed. Next, in step S 102 , the detection circuit  30  detects the liquid  29  in the liquid container  20  using the detection electrodes  40  ( 40   1 ,  40   2 , . . . ,  40   n ). 
     In step S 103 , the detection circuit  30  determines whether or not there is a difference in capacitance values of the detection electrodes  40  ( 40   1 ,  40   2 , . . . ,  40   n ) detected in the step S 102 . 
     When it is determined in the step S 103  that there is no difference in capacitance values of the detection electrodes  40  ( 40   1 ,  40   2 , . . . ,  40   n ), the detection circuit  30  determines that the liquid container  20  is not tilted, and detects the remaining amount of the liquid  29  in a normal state (no-tilted state) (step S 104 ). 
     When it is determined in the step S 103  that there is a difference in capacitance values of the detection electrodes  40  ( 40   1 ,  40   2 , . . . ,  40   n ), the detection circuit  30  determines that the liquid container  20  is tilted, detects a tilt degree (angle and direction) of the liquid container  20  based on detected capacitance values (step S 105 ), and detects the level (remaining amount) of the liquid  29  in response to the angle and direction of the tilt of the liquid container  20  (step S 106 ). 
     When it is determined in the steps S 104  and S 106  that the liquid level is low, the detection circuit  30  may output a warning such as a warning message or a warning sound. 
     (Method of Identifying Liquid Container in Second Embodiment) 
       FIG. 26  schematically illustrates a process sequence for identifying the liquid container  20  according to the second embodiment. 
     For example, when the printer main body  100  or the like is powered on or an ink cartridge is replaced with a new one, the process is started (step S 200 ). Thereafter, identification is performed for all the liquid containers  20  mounted on the mounting part such as the ink mounting unit  10 . 
     First, in step S 201 , the detection circuit  30  initializes a number counter n of the liquid container  20  by setting the number counter n to be zero. 
     Next, in step S 202 , the detection circuit  30  increases the number counter n of the liquid container  20  by one and starts processing of the n th  liquid container  20 . 
     In step S 203 , based on the arrangement patterns of the detection electrodes  40  ( 40   1 ,  40   2 , . . . ,  40   n ) of the n th  liquid container  20 , the detection circuit  30  determines whether or not the n th  liquid container  20  is mounted in a predetermined position. 
     When it is determined in the step S 203  that the arrangement pattern of the n th  liquid container  20  does not match a predetermined arrangement pattern, the detection circuit  30  determines that the n th  liquid container  20  is not mounted in the predetermined position (step S 204 ), and outputs a warning such as a warning message or a warning sound (step S 205 ). 
     When it is determined in the step S 203  that the arrangement pattern of the n th  liquid container  20  matches the predetermined arrangement pattern, the detection circuit  30  determines that the n th  liquid container  20  is correctly mounted in the predetermined position, and then determines whether or not the number counter n of the liquid container  20  has reached the number of liquid containers  20  (step S 206 ). 
     When it is determined in the step S 206  that the number counter n of the liquid container  20  has not reached the number of liquid containers  20 , the detection circuit  30  returns to the step S 202  to perform the identification process of the next liquid container  20 . 
     When it is determined in the step S 206  that the number counter n of the liquid container  20  has reached the number of liquid containers  20 , the detection circuit  30  determines that all the liquid containers  20  are correctly mounted in the predetermined positions, and the process is ended (step S 207 ). 
     (Method of Detecting Liquid Remaining Amount of Liquid Container According to Third Embodiment) 
       FIG. 27  schematically illustrates a process sequence of a method of detecting the liquid remaining amount in the liquid container  20  according to the third embodiment. 
     For example, when the printer main body  100  or the like is powered on (or the engine of a car is started), the process is started (step S 300 ). 
     First, in step S 301 , the detection circuit  30  performs a calibration using the detection electrode  40   2 , and sets and stores a reference capacitance value according to a state of the liquid container  20 . 
     Next, in step S 302 , the detection circuit  30  detects the remaining amount of the liquid  29  while referring to the reference capacitance value and a previously detected capacitance value as necessary. The detection circuit  30  detects the remaining amount of the liquid  29  by determining whether or not there is a difference in capacitance values of the detection electrodes  40   1  and  40   2 . 
     When it is determined in the step S 302  that there is no difference in capacitance values of the detection electrodes  40   1  and  40   2 , the detection circuit  30  determines that the liquid level is not yet low (not lower than the position of the detection electrode  40   1 ), and enters a standby state (step S 303 ). Upon entering the standby state in the step S 303 , the detection circuit  30  detects the remaining amount of the liquid  29  regularly or irregularly, for example, using a timer (whether or not a predetermined period has elapsed) or an interrupt of an event (printing or the like) as a trigger. 
     When it is determined in the step S 302  that there is a difference in capacitance values of the detection electrodes  40   1  and  40   2 , the detection circuit  30  determines that the liquid level is low (lower than the position of the detection electrode  40   1 ) (step S 304 ), and outputs a warning such as a warning message or a warning sound (step S 305 ). 
     As described above, according to the first to third embodiments, it is possible to provide a liquid container, a liquid remaining amount detection circuit of the liquid container, a liquid remaining amount detection method, a liquid container identification method, an ink mounting unit, a printer, and a print system, which are capable of detecting the remaining amount of liquid such as ink with high precision with a simple and inexpensive mechanism and identifying a liquid container such as an ink cartridge with a simple and inexpensive mechanism. 
     OTHER EMBODIMENTS 
     As described above, although the first to third embodiments of the present disclosure has been illustrated, the description and drawings which constitute a part of this disclosure are presented by way of example only and should not be construed to limit the present disclosure. Various alternative embodiments, examples and operation techniques will be apparent to those skilled in the art from this disclosure. 
     For example, in the first to third embodiments, the ink for a printer and the fuel for a car have been described. However, the present disclosure can be equally applied to detection of a remaining amount of other fluids that can be detected by a capacitance method or a pressure-sensitive resistive film method. 
     Thus, the present disclosure encompasses various embodiments not described here. 
     The first to third embodiments are applicable to various application fields including a printer, a copying machine, a multifunction peripheral, a fuel cell of a car, a cash register at a retail store, a ticket machine at a restaurant, a ticket vending machine at a station or an airport, etc. 
     According to the present disclosure in some embodiments, it is possible to provide a liquid container, a liquid remaining amount detection circuit of the liquid container, a liquid remaining amount detection method, a liquid container identification method, an ink mounting unit, a printer, and a print system, which are capable of detecting the remaining amount of liquid such as ink with high precision with a simple and inexpensive mechanism and identifying a liquid container such as an ink cartridge with a simple and inexpensive mechanism. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosures. Indeed, the novel methods and apparatuses described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the disclosures. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosures.