Liquid discharge device and liquid storage device

Abstract

To detect a residual quantity of liquid in a storage container.SOLUTION: A liquid discharge device includes: a storage container configured to store conductive liquid; a reference electrode housed in the storage container; a first electrode housed in the storage container; a second electrode housed in the storage container; an output part which is electrically connected to the first electrode and the second electrode and outputs an output signal generated according to an electric signal from the first electrode and the second electrode; and an identification part which identifies the residual quantity of the liquid stored in the storage container on the basis of the output signal. The first electrode contacts with the liquid stored in the storage container when a first quantity of the liquid or larger is stored in the storage container, the second electrode contacts with the liquid stored in the storage container when a second quantity, which is larger than the first quantity, of the liquid or larger is stored in the storage container, and the reference electrode contacts with the liquid stored in the storage container when the first quantity of the liquid is stored in the storage container. A resistance value of a first wiring path ranging from the first electrode to an output circuit is higher than a resistance value of a second wiring path ranging from the second electrode to the output circuit.SELECTED DRAWING: Figure 15

Description

Technical Field

[0001] The present invention relates to a liquid ejection device and a liquid storage device.

Background Art

[0002] Various techniques for detecting the remaining amount of liquid in a storage container that stores a conductive liquid such as ink have been proposed. For example, Patent Document 1 proposes a technique for detecting the remaining amount of liquid in a storage container based on the resistance value between two rod-shaped electrode pins provided in the storage container that stores the liquid.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional technology, since the change amount of the resistance value between the two electrode pins is smaller than the change amount of the remaining amount of liquid in the storage container, it may be difficult to detect the remaining amount of liquid in the storage container.

Means for Solving the Problems

[0005] In order to solve the above problems, a liquid ejection device according to the present invention includes a storage container that stores a conductive liquid, a reference electrode stored in the storage container, a first electrode stored in the storage container, a second electrode stored in the storage container, an output unit that is electrically connected to the first electrode and the second electrode and outputs an output signal according to an electrical signal from the first electrode and the second electrode, and a specifying unit that specifies the remaining amount of the liquid stored in the storage container based on the output signal. The first electrode contacts the liquid stored in the storage container when the storage container stores a liquid in an amount equal to or greater than a first amount. The second electrode contacts the liquid stored in the storage container when the storage container stores a liquid in an amount equal to or greater than a second amount that is greater than the first amount. The reference electrode contacts the liquid stored in the storage container when the storage container stores a liquid in the first amount. A resistance value of a first wiring path from the first electrode to the output circuit is higher than a resistance value of a second wiring path from the second electrode to the output circuit.

[0006] Further, a liquid storage device according to the present invention includes a storage container that stores a conductive liquid, a reference electrode stored in the storage container, a first electrode stored in the storage container, a second electrode stored in the storage container, and an output unit that is electrically connected to the first electrode and the second electrode and outputs an output signal according to an electrical signal from the first electrode and the second electrode. The first electrode contacts the liquid stored in the storage container when the storage container stores a liquid in an amount equal to or greater than a first amount. The second electrode contacts the liquid stored in the storage container when the storage container stores a liquid in an amount equal to or greater than a second amount that is greater than the first amount. The reference electrode contacts the liquid stored in the storage container when the storage container stores a liquid in the first amount. A resistance value of a first wiring path from the first electrode to the output circuit is higher than a resistance value of a second wiring path from the second electrode to the output circuit.

Brief Description of the Drawings

[0007]

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Mode for Carrying Out the Invention

[0008] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, in each figure, the dimensions and scales of each part are appropriately different from the actual ones. Further, the embodiments described below are preferred specific examples of the present invention, and thus various technically preferable limitations are imposed. However, the scope of the present invention is not limited to these embodiments unless otherwise specified in the following description to limit the present invention.

[0009] <<1. First Embodiment>> Hereinafter, the inkjet printer 100 according to the first embodiment will be described.

[0010] <<1.1. Outline of Inkjet Printer>> FIG. 1 is an explanatory diagram showing an example of the configuration of the inkjet printer 100 according to the present embodiment.

[0011] The inkjet printer 100 is an inkjet printing device that discharges ink IK onto a medium PP. The medium PP is typically printing paper, but any printing target such as a resin film or fabric can be used as the medium PP. In the present embodiment, conductive ink is adopted as the ink IK. In addition, in the present embodiment, the inkjet printer 100 is an example of a "liquid ejection device", and the ink IK is an example of a "conductive liquid".

[0012] As shown in FIG. 1, the inkjet printer 100 includes an ink storage device 1A, a control device 8, a plurality of liquid ejection heads HU, a conveyance mechanism 91, and a movement mechanism 92.

[0013] The control device 8 includes, for example, a processing circuit such as a CPU or an FPGA, and a storage circuit such as a semiconductor memory, and controls each element of the inkjet printer 100. Here, the CPU is an abbreviation for Central Processing Unit, and the FPGA is an abbreviation for Field Programmable Gate Array.

[0014] Based on the control by the control device 8, the conveyance mechanism 91 conveys the medium PP in the sub-scanning direction MP1. Based on the control by the control device 8, the movement mechanism 92 reciprocates the plurality of liquid ejection heads HU in the main scanning direction MH1 intersecting the sub-scanning direction MP1 and the main scanning direction MH2 opposite to the main scanning direction MH1. The movement mechanism 92 includes a storage case 921 that houses the plurality of liquid ejection heads HU and an endless belt 922 to which the storage case 921 is fixed. Note that the storage case 921 may house the ink storage device 1A together with the liquid ejection heads HU.

[0015] The control device 8 supplies a drive signal Com for driving the liquid ejection head HU and a control signal SI for controlling the liquid ejection head HU to the liquid ejection head HU.

[0016] The liquid ejection head HU is driven by a drive signal Com based on control by a control signal SI, and ejects ink IK from some or all of a plurality of nozzles provided in the liquid ejection head HU. That is, the liquid ejection head HU ejects ink IK from some or all of the plurality of nozzles in conjunction with the conveyance of the medium PP by the conveyance mechanism 91 and the reciprocating movement of the liquid ejection head HU by the movement mechanism 92, and lands the ejected ink on the surface of the medium PP, thereby forming a desired image on the surface of the medium PP.

[0017] The ink storage device 1A stores ink IK. Further, the ink storage device 1A supplies the ink IK stored in the ink storage device 1A to the liquid ejection head HU based on control by the control device 8. In the present embodiment, the ink storage device 1A is an example of a "liquid storage device".

[0018] In the present embodiment, it is assumed that the ink storage device 1A stores M types of ink IK. Here, the value M is a natural number satisfying 1 ≦ M. More specifically, in the present embodiment, as an example, it is assumed that the ink storage device 1A stores four types of ink IK corresponding to cyan, magenta, yellow, and black. That is, in the present embodiment, as an example, the case of "M = 4" is assumed.

[0019] In the present embodiment, it is assumed that the inkjet printer 100 includes M liquid ejection heads HU corresponding to M types of ink IK. Specifically, in the present embodiment, as an example, it is assumed that the inkjet printer 100 includes four liquid ejection heads HU corresponding to four types of ink IK. Hereinafter, among the M liquid ejection heads HU, the m-th liquid ejection head HU may be referred to as the liquid ejection head HU[m]. Here, the variable m is a natural number satisfying 1 ≦ m ≦ M.

[0020] The ink storage device 1A includes an ink quantity detection circuit 2A that detects the remaining quantity of various types of ink IK stored in the ink storage device 1A and outputs an output signal Vout indicating the detection result. Note that the ink quantity detection circuit 2A will be described later with reference to FIG. 3.

[0021] <<1.2. Ink Storage Device>> Hereinafter, the outline of the ink storage device 1A will be described with reference to FIGS. 2 to 7.

[0022] FIG. 2 is a perspective view for explaining an example of the configuration of the ink storage device 1A.

[0023] As shown in FIG. 2, the ink storage device 1A includes M ink tanks TK that correspond one-to-one with M types of ink IK stored in the ink storage device 1A, and a storage case 11 that houses the M ink tanks TK. Specifically, in the present embodiment, the ink storage device 1A includes four ink tanks TK that correspond one-to-one with four types of ink IK: cyan, magenta, yellow, and black. Note that in the present embodiment, the ink tank TK is an example of a "storage container".

[0024] Hereinafter, among the M ink tanks TK, the m-th ink tank TK may be referred to as ink tank TK[m]. The ink tank TK[m] stores the type of ink IK corresponding to the ink tank TK[m] and supplies the ink IK to the liquid ejection head HU[m] corresponding to the ink tank TK[m].

[0025] In the present embodiment, the ink tank TK is provided with a supply port 12 for supplying the ink IK to the internal space of the ink tank TK. Further, the ink tank TK houses an electrode rod BT, an electrode rod B1, and an electrode rod B2, which are rod-shaped electrodes. Note that in the present embodiment, the electrode rod BT is an example of a "reference electrode", the electrode rod B1 is an example of a "first electrode", and the electrode rod B2 is an example of a "second electrode".

[0026] Hereinafter, when ink IK is supplied from the ink tank TK to the liquid ejection head HU and the ink IK stored inside the ink tank TK decreases, the direction in which the ink IK decreases in the ink tank TK is referred to as the Z1 direction. Further, in the present embodiment, as an example, a case where the electrode bar BT, the electrode bar B1, and the electrode bar B2 are provided so as to extend in the Z1 direction in the ink tank TK is assumed. Hereinafter, the Z1 direction and the Z2 direction opposite to the Z1 direction are collectively referred to as the Z-axis direction.

[0027] FIG. 3 is a circuit diagram showing an example of the configuration of the ink amount detection circuit 2A provided in the ink storage device 1A. In the present embodiment, a case where M ink amount detection circuits 2A corresponding one-to-one to M ink tanks TK[1] to TK[M] are provided in the ink storage device 1A is assumed.

[0028] As shown in FIG. 3, the ink amount detection circuit 2A includes an output circuit 20, an input terminal TnN, a detection terminal TnK1, a detection terminal TnK2, a reference potential connection terminal TnT, and an output terminal TnS.

[0029] The output circuit 20 includes a node NK and an input resistor RN provided between the input terminal TnN and the node NK. Note that in the present embodiment, the output circuit 20 is an example of an "output unit".

[0030] The node NK is electrically connected to the input terminal TnN, the detection terminal TnK1, the detection terminal TnK2, and the output terminal TnS. The detection terminal TnK1 is electrically connected to the electrode bar B1 via the detection wiring LK1. The detection terminal TnK2 is electrically connected to the electrode bar B2 via the detection wiring LK2. The reference potential connection terminal TnT is electrically connected to the ground wiring set to the ground potential and is also electrically connected to the electrode bar BT via the reference potential connection wiring LT.

[0031] In this embodiment, when ink IK is stored in ink tank TK and electrode rod BT and electrode rod B1 come into contact with the ink IK stored in ink tank TK, electrode rod BT and electrode rod B1 are electrically connected via the ink IK stored in ink tank TK. Hereinafter, when electrode rod BT and electrode rod B1 are electrically connected via the ink IK stored in ink tank TK, the electrical resistance of the ink IK that electrically connects electrode rod BT and electrode rod B1 is referred to as ink resistance RT1.

[0032] Also, in this embodiment, when ink IK is stored in ink tank TK and electrode rod BT and electrode rod B2 come into contact with the ink IK stored in ink tank TK, electrode rod BT and electrode rod B2 are electrically connected via the ink IK stored in ink tank TK. Hereinafter, when electrode rod BT and electrode rod B2 are electrically connected via the ink IK stored in ink tank TK, the electrical resistance of the ink IK that electrically connects electrode rod BT and electrode rod B2 is referred to as ink resistance RT2.

[0033] In this embodiment, an input signal Vin set to a constant input potential VN is input to input terminal TnN. Therefore, when electrode rod BT and electrode rod B1 are electrically connected via the ink IK stored in ink tank TK, the potential of node NK is determined based on the input potential VN of input signal Vin, the resistance value of input resistance RN, and the resistance value of ink resistance RT1. Also, when electrode rod BT and electrode rod B2 are electrically connected via the ink IK stored in ink tank TK, the potential of node NK is determined based on the input potential VN of input signal Vin, the resistance value of input resistance RN, and the resistance value of ink resistance RT2. In this embodiment, since the input potential VN of input signal Vin and the resistance value of input resistance RN are constant values, the potential of node NK will be determined based on the resistance values of ink resistance RT1 and ink resistance RT2. Then, an output signal Vout indicating the potential of node NK is output from output terminal TnS.

[0034] In the present embodiment, the control device 8 specifies the remaining amount of the ink IK stored in the ink tank TK based on the output signal Vout output by the output circuit 20. Note that in the present embodiment, the control device 8 is an example of the "specifying unit".

[0035] FIGS. 4 and 5 are configuration diagrams showing an example of the configurations of the electrode rod BT, the electrode rod B1, and the electrode rod B2.

[0036] As shown in FIGS. 4 and 5, the electrode rod BT includes a conductive electrode component GT extending in the Z1 direction, and a conductive connection portion GTt extending in the Z1 direction and electrically connecting the electrode component GT and the reference potential connection wiring LT. In the present embodiment, it is assumed that the electrode component GT is provided such that the distance in the Z-axis direction from the end portion of the electrode rod BT in the Z1 direction to the bottom surface TM of the ink tank TK is the distance HE.

[0037] Further, the electrode rod B1 includes a conductive electrode component G1 extending in the Z1 direction, and a conductive connection portion G1t extending in the Z1 direction and electrically connecting the electrode component G1 and the detection wiring LK1. In the present embodiment, it is assumed that the electrode component G1 is provided such that the distance in the Z-axis direction from the end portion of the electrode rod B1 in the Z1 direction to the bottom surface TM of the ink tank TK is the distance H1. Here, the distance H1 is a distance longer than the distance HE.

[0038] Further, the electrode rod B2 includes a conductive electrode component G2 extending in the Z1 direction, and a conductive connection portion G2t extending in the Z1 direction and electrically connecting the electrode component G2 and the detection wiring LK2. In the present embodiment, it is assumed that the electrode component G2 is provided such that the distance in the Z-axis direction from the end portion of the electrode rod B2 in the Z1 direction to the bottom surface TM of the ink tank TK is the distance H2. Here, the distance H2 is a distance longer than the distance H1.

[0039] In this embodiment, as an example, it is assumed that the electrode components GT, G1, and G2 are provided such that the distance in the Z-axis direction from the end portion of the electrode component GT in the Z2 direction to the bottom surface TM of the ink tank TK, the distance in the Z-axis direction from the end portion of the electrode component G1 in the Z2 direction to the bottom surface TM of the ink tank TK, and the distance in the Z-axis direction from the end portion of the electrode component G2 in the Z2 direction to the bottom surface TM of the ink tank TK are all the distance HF. Here, the distance HF is longer than the distance H2.

[0040] Hereinafter, the distance in the Z-axis direction from the bottom surface TM of the ink tank TK to the liquid surface SF of the ink IK accommodated in the ink tank TK is referred to as the ink liquid surface distance SZ.

[0041] As shown in FIG. 4, when ink IK exists between the electrode bar BT and the electrode bar B1, that is, when the ink liquid surface distance SZ is equal to or greater than the distance H1, the electrode bar BT and the electrode bar B1 are electrically connected by the ink IK. Therefore, when the ink liquid surface distance SZ is equal to or greater than the distance H1, the electrode bar BT and the electrode bar B1 are electrically connected by the ink IK having the ink resistance RT1. In this embodiment, the amount of ink in the ink tank TK such that the ink liquid surface distance SZ is equal to the distance H1 is an example of the "first amount".

[0042] As shown in FIG. 5, when ink IK exists between the electrode bar BT and the electrode bar B2, that is, when the ink liquid surface distance SZ is equal to or greater than the distance H2, the electrode bar BT and the electrode bar B2 are electrically connected by the ink IK. Therefore, when the ink liquid surface distance SZ is equal to or greater than the distance H2, the electrode bar BT and the electrode bar B2 are electrically connected by the ink IK having the ink resistance RT2. In this embodiment, the amount of ink in the ink tank TK such that the ink liquid surface distance SZ is equal to the distance H2 is an example of the "second amount".

[0043] Incidentally, hereinafter, the electrical resistance in the electrical connection path from the electrode bar BT to the node NK is referred to as the combined resistance RG. When the electrical resistances of the detection wiring LK1, the detection wiring LK2, the electrode bar B1, and the electrode bar B2 are sufficiently small, the combined resistance RG will have substantially the same resistance value as the combined resistance of the ink resistances RT1 and RT2.

[0044] In this specification, "substantially the same" is a concept that includes cases where, in addition to being exactly the same, it can be regarded as the same when considering errors. Specifically, in this specification, "substantially the same" is a concept that includes cases where it can be regarded as the same when considering an error of about 10%.

[0045] FIG. 6 and FIG. 7 are circuit diagrams for explaining the combined resistance RG. Among them, FIG. 6 is a diagram showing the combined resistance RG when the ink liquid surface distance SZ is equal to or greater than the distance H1 and less than the distance H2. FIG. 7 is a diagram showing the combined resistance RG when the ink liquid surface distance SZ is equal to or greater than the distance H2.

[0046] As shown in FIG. 6, when the ink liquid surface distance SZ is equal to or greater than the distance H1 and less than the distance H2, the electrode bar BT and the electrode bar B1 are electrically connected by the ink IK, while the electrode bar BT and the electrode bar B2 are not electrically connected. Therefore, when the ink liquid surface distance SZ is equal to or greater than the distance H1 and less than the distance H2, the combined resistance RG becomes substantially the same as the ink resistance RT1.

[0047] As shown in FIG. 7, when the ink liquid surface distance SZ is equal to or greater than the distance H2, the electrode bar BT and the electrode bar B1 are electrically connected by the ink IK, and the electrode bar BT and the electrode bar B2 are electrically connected by the ink IK. Therefore, when the ink liquid surface distance SZ is equal to or greater than the distance H2, the combined resistance RG becomes substantially the same as the combined resistance of the ink resistances RT1 and RT2 when the ink resistances RT1 and RT2 are connected in parallel.

[0048] In addition, in this embodiment, as an example, it is assumed that the resistance value of the first wiring path from the electrode bar B1 to the node NK via the detection wiring LK1 and the detection terminal TnK1 and the resistance value of the second wiring path from the electrode bar B2 to the node NK via the detection wiring LK2 and the detection terminal TnK2 are substantially the same.

[0049] <<1.3. Reference Example>> Hereinafter, with reference to FIGS. 8 to 14, the outline of the inkjet printer according to the reference example and the effects of the first embodiment will be described. Note that the inkjet printer according to the reference example differs from the inkjet printer 100 according to the first embodiment in that it includes an ink storage device 1W instead of the ink storage device 1A.

[0050] FIG. 8 is a circuit diagram for explaining the configuration of the ink storage device 1W.

[0051] As shown in FIG. 8, the ink storage device 1W differs from the ink storage device 1 according to the first embodiment in that it includes an ink tank TK-W instead of the ink tank TK and an ink amount detection circuit 2W instead of the ink amount detection circuit 2. The ink tank TK-W differs from the ink tank TK according to the first embodiment in that it does not include the electrode bar B2. That is, the ink tank TK-W houses the electrode bar BT and the electrode bar B1. The ink amount detection circuit 2W differs from the ink amount detection circuit 2 according to the first embodiment in that it does not include the detection terminal TnK2. That is, the ink amount detection circuit 2W includes a detection terminal TnK1 electrically connected to the electrode bar B1 via the detection wiring LK1 and a reference potential connection terminal TnT electrically connected to the electrode bar BT via the reference potential connection wiring LT.

[0052] Note that in the inkjet printer according to the reference example, the combined resistance RG, which is the electrical resistance in the electrical connection path from the electrode bar BT to the node NK, is substantially the same as the ink resistance RT1. Hereinafter, when distinction is necessary, the combined resistor RG in the first embodiment may be referred to as combined resistor RG-A, and the combined resistor RG in the reference example may be referred to as combined resistor RG-W.

[0053] <<1.4. Relationship between Ink Liquid Surface Distance, Combined Resistor, and Output Signal>> FIG. 9 is an explanatory diagram for explaining a resistance value change curve CRA according to the first embodiment and a resistance value change curve CRW according to the reference example. Here, the resistance value change curve CRA is a curve showing the relationship between the resistance value of the combined resistor RG-A in the first embodiment and the ink liquid surface distance SZ. The resistance value change curve CRW is a curve showing the relationship between the resistance value of the combined resistor RG-W in the reference example and the ink liquid surface distance SZ. In FIG. 9, the horizontal axis represents the ink liquid surface distance SZ, and the vertical axis represents the resistance value of the combined resistor RG, so that the relationship between the ink liquid surface distance SZ and the resistance value of the combined resistor RG is represented as the resistance value change curve CRA and the resistance value change curve CRW.

[0054] As described above, when the ink liquid surface distance SZ is less than the distance H1, the electrode bar B1 and the electrode bar B2 do not contact the ink IK. That is, when the ink liquid surface distance SZ is less than the distance H1, the electrode bar BT and the electrode bar B1 are in a non-electrically connected state, and the electrode bar BT and the electrode bar B2 are also in a non-electrically connected state. On the other hand, when the ink liquid surface distance SZ is greater than or equal to the distance H1, the electrode bar B1 contacts the ink IK. That is, when the ink liquid surface distance SZ is greater than or equal to the distance H1, the electrode bar BT and the electrode bar B1 are in an electrically connected state.

[0055] Therefore, as shown by the resistance value change curve CRA in FIG. 9, in the first embodiment, when the ink liquid surface distance SZ is greater than or equal to the distance H1, the combined resistor RG-A has a smaller resistance value compared to the case where the ink liquid surface distance SZ is less than the distance H1. That is, in the present embodiment, the resistance value change curve CRA has a change region A-RA1 where the combined resistor RG-A changes greatly at the boundary between the case where the ink liquid surface distance SZ is less than the distance H1 and the case where the ink liquid surface distance SZ is greater than or equal to the distance H1.

[0056] Similarly, as shown by the resistance value change curve CRW in Fig. 9, also in the reference example, when the ink liquid surface distance SZ is greater than or equal to the distance H1, the combined resistance RG-W has a smaller resistance value compared to the case where the ink liquid surface distance SZ is less than the distance H1. That is, in the present embodiment, the resistance value change curve CRW also has a change region A-RA1 where the combined resistance RG-W changes significantly at the boundary between the case where the ink liquid surface distance SZ is less than the distance H1 and the case where the ink liquid surface distance SZ is greater than or equal to the distance H1, similar to the resistance value change curve CRA.

[0057] Also, when the ink liquid surface distance SZ is greater than or equal to the distance H1 and less than the distance H2, the electrode bar B1 contacts the ink IK while the electrode bar B2 does not contact the ink IK. That is, when the ink liquid surface distance SZ is greater than or equal to the distance H1 and less than the distance H2, the electrode bar BT and the electrode bar B1 are electrically connected by the ink IK having the ink resistance RT1. And as the ink liquid surface distance SZ increases and the cross-sectional area of the ink IK that electrically connects the electrode bar BT and the electrode bar B1 increases, the resistance value of the ink resistance RT1 decreases.

[0058] Therefore, as shown by the resistance value change curve CRA in Fig. 9, in the first embodiment, when the ink liquid surface distance SZ is greater than or equal to the distance H1 and less than the distance H2, as the ink liquid surface distance SZ increases, the resistance value of the combined resistance RG-A decreases. Similarly, as shown by the resistance value change curve CRW in Fig. 9, also in the reference example, when the ink liquid surface distance SZ is greater than or equal to the distance H1 and less than the distance H2, as the ink liquid surface distance SZ increases, the resistance value of the combined resistance RG-W decreases.

[0059] Also, when the ink liquid surface distance SZ is greater than or equal to the distance H2, the electrode bar B1 and the electrode bar B2 come into contact with the ink IK. That is, when the ink liquid surface distance SZ is greater than or equal to the distance H2, the electrode bar BT and the electrode bar B1 are electrically connected by the ink IK having the ink resistance RT1, and the electrode bar BT and the electrode bar B2 are electrically connected by the ink IK having the ink resistance RT2. And when the ink resistance RT1 and the ink resistance RT2 are connected in parallel, the resistance value of the combined resistance of the ink resistance RT1 and the ink resistance RT2 is smaller than the individual resistance value of the ink resistance RT1.

[0060] Therefore, as shown by the resistance value change curve CRA in FIG. 9, in the first embodiment, when the ink liquid surface distance SZ is greater than or equal to the distance H2, the combined resistance RG-A has a smaller resistance value compared to when the ink liquid surface distance SZ is less than the distance H2. That is, in the first embodiment, the resistance value change curve CRA has a change region A-RA2 where the combined resistance RG-A changes significantly at the boundary between the case where the ink liquid surface distance SZ is less than the distance H2 and the case where the ink liquid surface distance SZ is greater than or equal to the distance H2.

[0061] On the other hand, in the reference example, the electrode bar B2 is not provided in the ink tank TK-W. That is, in the reference example, both the combined resistance RG-W when the ink liquid surface distance SZ is less than the distance H2 and the combined resistance RG-W when the ink liquid surface distance SZ is greater than or equal to the distance H2 are the ink resistance RT1. For this reason, as shown in FIG. 9, the resistance value change curve CRW according to the reference example does not have the change region A-RA2.

[0062] Also, as the ink liquid surface distance SZ increases and the cross-sectional area of the ink IK that electrically connects the electrode bar BT and the electrode bar B1 increases, the resistance value of the ink resistance RT1 decreases. Also, as the ink liquid surface distance SZ increases and the cross-sectional area of the ink IK that electrically connects the electrode bar BT and the electrode bar B2 increases, the resistance value of the ink resistance RT2 decreases. Therefore, as shown by the resistance value change curve CRA in FIG. 9, in the first embodiment, when the ink liquid surface distance SZ is greater than or equal to the distance H2, as the ink liquid surface distance SZ increases, the resistance value of the combined resistance RG-A decreases. Similarly, as shown by the resistance value change curve CRW in FIG. 9, also in the reference example, when the ink liquid surface distance SZ is greater than or equal to the distance H2, as the ink liquid surface distance SZ increases, the resistance value of the combined resistance RG-W decreases.

[0063] Thus, both the resistance value change curve CRA and the resistance value change curve CRW have a change region A-RA1. For this reason, the resistance value change curve CRA has substantially the same shape as the resistance value change curve CRW when the ink liquid surface distance SZ is less than the distance H2. Also, the resistance value change curve CRA has a change region A-RA2, while the resistance value change curve CRW does not have a change region A-RA2 and has a smooth shape in which the combined resistance RG-W continuously decreases as the ink liquid surface distance SZ increases. For this reason, the resistance value change curve CRA shows a lower resistance value than the resistance value change curve CRW when the ink liquid surface distance SZ is greater than or equal to the distance H2.

[0064] FIG. 10 is an explanatory diagram for explaining the potential change curve CVA according to the first embodiment and the potential change curve CVW according to the reference example. Here, the potential change curve CVA is a curve showing the relationship between the output signal Vout output from the ink amount detection circuit 2 in the first embodiment and the ink liquid surface distance SZ. Also, the potential change curve CVW is a curve showing the relationship between the output signal Vout output from the ink amount detection circuit 2W in the reference example and the ink liquid surface distance SZ. In FIG. 10, the horizontal axis represents the ink liquid surface distance SZ, and the vertical axis represents the potential of the output signal Vout, thereby representing the relationship between the ink liquid surface distance SZ and the potential of the output signal Vout as the potential change curve CVA and the potential change curve CVW. Hereinafter, when distinction is necessary, the output signal Vout output from the ink amount detection circuit 2 in the first embodiment may be referred to as the output signal Vout-A, and the output signal Vout output from the ink amount detection circuit 2W in the reference example may be referred to as the output signal Vout-W.

[0065] As described above, the potential of the output signal Vout, that is, the potential of the node NK, is determined based on the resistance value of the combined resistor RG. Specifically, when the resistance value of the combined resistor RG is large, the potential of the output signal Vout becomes higher compared to the case when it is small.

[0066] Therefore, as shown by the potential change curve CVA in FIG. 10, in the first embodiment, when the ink liquid surface distance SZ is equal to or greater than the distance H1, the output signal Vout-A has a lower potential compared to the case when the ink liquid surface distance SZ is less than the distance H1. Also, as shown by the potential change curve CVA, when the ink liquid surface distance SZ is equal to or greater than the distance H2, the output signal Vout-A has a lower potential compared to the case when the ink liquid surface distance SZ is less than the distance H2. That is, as shown by the potential change curve CVA, as the ink liquid surface distance SZ increases, the potential of the output signal Vout-A decreases.

[0067] Note that, as described above, the resistance value change curve CRA has the change regions A-RA1 and A-RA2. For this reason, as shown in FIG. 10, the potential change curve CVA also has the change regions A-VA1 and A-VA2 where the rate of change of the potential of the output signal Vout-A becomes large with respect to the change in the ink liquid surface distance SZ. Here, the change region A-VA1 is a region corresponding to the change region A-RA1, and is a region where the potential of the output signal Vout-A changes significantly at the boundary between the case where the ink liquid surface distance SZ is less than the distance H1 and the case where the ink liquid surface distance SZ is equal to or greater than the distance H1. Also, the change region A-VA2 is a region corresponding to the change region A-RA2, and is a region where the potential of the output signal Vout-A changes significantly at the boundary between the case where the ink liquid surface distance SZ is less than the distance H2 and the case where the ink liquid surface distance SZ is equal to or greater than the distance H2.

[0068] Also, as shown by the potential change curve CVW in FIG. 10, in the reference example, when the ink liquid surface distance SZ is greater than or equal to the distance H1, the output signal Vout-W is at a lower potential compared to the case where the ink liquid surface distance SZ is less than the distance H1. Further, as shown by the potential change curve CVW, when the ink liquid surface distance SZ is greater than or equal to the distance H2, the output signal Vout-W is at a lower potential compared to the case where the ink liquid surface distance SZ is less than the distance H2. That is, as shown by the potential change curve CVW, as the ink liquid surface distance SZ increases, the potential of the output signal Vout-W decreases.

[0069] As described above, the resistance value change curve CRW has the change region A-RA1 but does not have the change region A-RA2. Therefore, as shown in FIG. 10, the potential change curve CVW also has the change region A-VA1 but does not have the change region A-VA2.

[0070] Hereinafter, in the case where the temperature of the ink IK in the ink tank TK is the reference temperature t1 and the ink liquid surface distance SZ in the ink tank TK is the distance H1, the potential indicated by the output signal Vout-A in the first embodiment is referred to as the threshold potential Vth1. As shown in FIG. 10, in the case where the temperature of the ink IK in the ink tank TK-W is the reference temperature t1 and the ink liquid surface distance SZ in the ink tank TK-W is the distance H1, the potential indicated by the output signal Vout-W in the reference example is also the threshold potential Vth1. Also, hereinafter, in the case where the temperature of the ink IK in the ink tank TK is the reference temperature t1 and the ink liquid surface distance SZ in the ink tank TK is the distance H2, the potential indicated by the output signal Vout-A in the first embodiment is referred to as the threshold potential Vth2. As shown in FIG. 10, in the case where the temperature of the ink IK in the ink tank TK-W is the reference temperature t1 and the ink liquid surface distance SZ in the ink tank TK-W is the distance H2, the potential indicated by the output signal Vout-W represented by the potential change curve CVW in the reference example is at a potential higher than the threshold potential Vth2.

[0071] Here, the reference temperature t1 is, for example, the temperature of the ink IK in the ink tank TK when the inkjet printer 100 is used in a standard usage environment of the inkjet printer 100. Further, the reference temperature t1 may be, for example, the ambient temperature of the inkjet printer 100 when the inkjet printer 100 is used in a standard usage environment of the inkjet printer 100. Further, the reference temperature t1 may be, for example, the temperature of a standard usage environment of the ink IK.

[0072] As described above, in the first embodiment, the control device 8 identifies the remaining amount of the ink IK stored in the ink tank TK based on the output signal Vout-A.

[0073] Specifically, in the first embodiment, when the potential of the output signal Vout-A is higher than the threshold potential Vth1, the control device 8 identifies that the remaining amount of the ink IK in the ink tank TK is less than the ink amount corresponding to the distance H1, and when the potential of the output signal Vout-A is lower than the threshold potential Vth1, the control device 8 identifies that the remaining amount of the ink IK in the ink tank TK is more than the ink amount corresponding to the distance H1. Here, the ink amount corresponding to the distance H1 is an amount based on the minimum amount of the ink IK in the ink tank TK. Specifically, the amount based on the minimum amount of the ink IK in the ink tank TK may be the minimum ink amount that enables the ejection of the ink IK from the liquid ejection head HU by the ink IK supplied from the ink tank TK, or may be an ink amount such that the difference from the minimum ink amount is equal to or less than the first difference amount. Here, the first difference amount may be, for example, an ink amount equal to or less than the ink amount required for the inkjet printer 100 to form an image on a predetermined number of media PP, or may be an ink amount that enables the ejection of the ink IK from the liquid ejection head HU a predetermined number of times or less. That is, the ink amount corresponding to the distance H1 may be an ink amount corresponding to a state called a so-called "ink end". In addition, in the present embodiment, the ink amount corresponding to the distance H1, that is, the "first amount" is an example of the "amount based on the minimum amount of liquid in the storage container".

[0074] Also, in the first embodiment, when the potential of the output signal Vout-A is higher than the threshold potential Vth2, the control device 8 specifies that the remaining amount of the ink IK in the ink tank TK is less than the ink amount corresponding to the distance H2, and when the potential of the output signal Vout-A is lower than the threshold potential Vth2, the control device 8 specifies that the remaining amount of the ink IK in the ink tank TK is more than the ink amount corresponding to the distance H2. Here, the ink amount corresponding to the distance H2 is the amount based on the maximum amount of the ink IK in the ink tank TK. Specifically, the amount based on the maximum amount of the ink IK in the ink tank TK may be the maximum ink amount that can be stored in the ink tank TK, or may be an ink amount such that the difference from the maximum ink amount is equal to or less than the second difference amount. Here, the second difference amount may be, for example, the ink amount that can be supplied within a predetermined time when a user of the inkjet printer 100 supplies the ink IK into the ink tank TK through the supply port 12 from a bottle in which the ink IK is stored. Also, for example, the second difference amount may be the minimum ink amount of the ink IK that can be supplied to the ink tank TK by a bottle in which the ink IK is stored by the user of the inkjet printer 100. That is, the ink amount corresponding to the distance H2 may be the ink amount corresponding to a state called "full". In addition, in the present embodiment, the ink amount corresponding to the distance H2, that is, the "second amount" is an example of the "amount based on the maximum amount of liquid in the storage container".

[0075] Further, in the reference example, similar to the first embodiment, when the potential of the output signal Vout-W is higher than the threshold potential Vth1, the control device 8 specifies that the remaining amount of the ink IK in the ink tank TK-W is less than the ink amount corresponding to the distance H1, and when the potential of the output signal Vout-W is lower than the threshold potential Vth1, the control device 8 specifies that the remaining amount of the ink IK in the ink tank TK-W is greater than the ink amount corresponding to the distance H1. On the other hand, in the reference example, unlike the first embodiment, the control device 8 cannot specify whether the remaining amount of the ink IK in the ink tank TK-W is less than the ink amount corresponding to the distance H2 based on the determination result of whether the potential of the output signal Vout-W is higher than the threshold potential Vth2.

[0076] FIG. 11 is an explanatory diagram for explaining the temperature change of the resistance value change curve CRW accompanying the temperature change of the ink IK in the ink tank TK-W according to the reference example.

[0077] Specifically, in FIG. 11, the resistance value change curve CRW when the temperature of the ink IK in the ink tank TK-W is the reference temperature t1 is represented as the resistance value change curve CRW(t1), and the resistance value change curve CRW when the temperature of the ink IK in the ink tank TK-W is a temperature t2 different from the reference temperature t1 is represented as the resistance value change curve CRW(t2).

[0078] As shown in FIG. 11, when the temperature of the ink IK in the ink tank TK-W changes, the resistance value indicated by the resistance value change curve CRW also changes. Specifically, when the temperature of the ink IK in the ink tank TK-W changes from the reference temperature t1 to the temperature t2, the resistance value of the combined resistance RG-W indicated by the resistance value change curve CRW also changes. That is, when the ink liquid surface distance SZ is the same value, the resistance value of the combined resistance RG-W indicated by the resistance value change curve CRW(t1) and the resistance value of the combined resistance RG-W indicated by the resistance value change curve CRW(t2) are different. Note that, in FIG. 11, the case where the resistance value of the combined resistance RG-W indicated by the resistance value change curve CRW changes to a small value as the temperature of the ink IK in the ink tank TK-W changes is illustrated. However, the present invention is not limited to such a mode. As the temperature of the ink IK in the ink tank TK-W changes, the resistance value of the combined resistance RG-W indicated by the resistance value change curve CRW may change to a large value.

[0079] As described above, the resistance value change curve CRW according to the reference example has a change region A-RA1 at the portion where the ink liquid surface distance SZ is the distance H1. That is, in the change region A-RA1 including the portion where the ink liquid surface distance SZ is the distance H1 in the resistance value change curve CRW, the resistance value of the combined resistance RG-W indicated by the resistance value change curve CRW changes greatly. Therefore, in the vertical axis direction of the graph shown in FIG. 11, a part of the change region A-RA1 of the resistance value change curve CRW(t1) and a part of the change region A-RA1 of the resistance value change curve CRW(t2) overlap.

[0080] FIG. 12 is an explanatory diagram for explaining the temperature change of the potential change curve CVW accompanying the temperature change of the ink IK in the ink tank TK-W according to the reference example.

[0081] Specifically, in FIG. 12, the potential change curve CVW when the temperature of the ink IK in the ink tank TK-W is the reference temperature t1 is represented as the potential change curve CVW(t1), and the potential change curve CVW when the temperature of the ink IK in the ink tank TK-W is the temperature t2 is represented as the potential change curve CVW(t2).

[0082] As shown in FIG. 12, when the temperature of the ink IK in the ink tank TK-W changes, the potential indicated by the potential change curve CVW also changes. Specifically, when the temperature of the ink IK in the ink tank TK-W changes from the reference temperature t1 to the temperature t2, the potential of the output signal Vout-W indicated by the potential change curve CVW also changes. That is, even when the ink liquid surface distance SZ is the same value, the potential of the output signal Vout-W indicated by the potential change curve CVW(t1) and the potential of the output signal Vout-W indicated by the potential change curve CVW(t2) are different. In FIG. 12, an example is illustrated in which the potential of the output signal Vout-W indicated by the potential change curve CVW changes to a small value as the temperature of the ink IK in the ink tank TK-W changes. However, the present invention is not limited to such a mode. The potential of the output signal Vout-W indicated by the potential change curve CVW may change to a large value as the temperature of the ink IK in the ink tank TK-W changes.

[0083] Thus, in the ink storage device 1W according to the reference example, even when there is no change in the remaining amount of the ink IK in the ink tank TK-W, the potential of the output signal Vout-W output by the ink storage device 1W changes as the temperature of the ink IK in the ink tank TK-W changes. For this reason, the ink storage device 1W according to the reference example may not be able to appropriately detect the remaining amount of the ink IK.

[0084] Specifically, in the example shown in FIG. 12, when the temperature of the ink IK in the ink tank TK-W is the reference temperature t1 and the potential of the output signal Vout-W is less than the threshold potential Vth2, the remaining amount of the ink IK in the ink tank TK-W is larger than the ink amount corresponding to the distance H2. On the other hand, in the example shown in FIG. 12, when the temperature of the ink IK in the ink tank TK-W is the temperature t2 and the potential of the output signal Vout-W is less than the threshold potential Vth2, in addition to the possibility that the remaining amount of the ink IK in the ink tank TK-W is larger than the ink amount corresponding to the distance H2, there is also a possibility that it is larger than the ink amount corresponding to the distance H1. That is, even though the user of the inkjet printer recognizes that the potential of the output signal Vout-W is less than the threshold potential Vth2 and the remaining amount of the ink IK in the ink tank TK-W is larger than the ink amount corresponding to the distance H2, actually, there is also a possibility that the remaining amount of the ink IK in the ink tank TK-W is less than the ink amount corresponding to the distance H2. That is, in the ink storage device 1W according to the reference example, there is a possibility that it becomes difficult to detect the remaining amount of the ink IK in the ink tank TK-W based on the output signal Vout-W.

[0085] Note that in the ink storage device 1W, a temperature detection device for detecting the temperature of the ink IK in the ink tank TK-W is added, and by correcting the potential indicated by the output signal Vout-W according to the detection result of the temperature detection device, a mode of detecting the remaining amount of the ink IK in the ink tank TK-W based on the potential indicated by the corrected output signal Vout-W is also conceivable. However, in this case, there is a concern that the configuration of the ink storage device 1W becomes complicated as compared with the first embodiment described above.

[0086] FIG. 13 is an explanatory diagram for explaining the temperature change of the resistance value change curve CRA accompanying the temperature change of the ink IK in the ink tank TK according to the first embodiment.

[0087] Specifically, in FIG. 13, when the temperature of the ink IK in the ink tank TK is the reference temperature t1, the resistance value change curve CRA is represented as the resistance value change curve CRA(t1), and when the temperature of the ink IK in the ink tank TK is the temperature t2, the resistance value change curve CRA is represented as the resistance value change curve CRA(t2).

[0088] As shown in FIG. 13, when the temperature of the ink IK in the ink tank TK changes, the resistance value indicated by the resistance value change curve CRA also changes. Specifically, when the temperature of the ink IK in the ink tank TK changes from the reference temperature t1 to the temperature t2, the resistance value of the combined resistance RG-A indicated by the resistance value change curve CRA also changes. That is, when the ink liquid surface distance SZ is the same value, the resistance value of the combined resistance RG-A indicated by the resistance value change curve CRA(t1) and the resistance value of the combined resistance RG-A indicated by the resistance value change curve CRA(t2) are different. Note that in FIG. 13, an example is shown in which the resistance value of the combined resistance RG-A indicated by the resistance value change curve CRA changes to a smaller value as the temperature of the ink IK in the ink tank TK changes, but the present invention is not limited to such a mode. The resistance value of the combined resistance RG-A indicated by the resistance value change curve CRA may change to a larger value as the temperature of the ink IK in the ink tank TK changes.

[0089] As described above, the resistance value change curve CRA according to the first embodiment has a change region A-RA1 in the portion where the ink liquid surface distance SZ is the distance H1. That is, in the change region A-RA1 including the portion where the ink liquid surface distance SZ is the distance H1 in the resistance value change curve CRA, the resistance value of the combined resistance RG-A indicated by the resistance value change curve CRA changes greatly. Therefore, in the vertical axis direction of the graph shown in FIG. 13, a part of the change region A-RA1 of the resistance value change curve CRA(t1) and a part of the change region A-RA1 of the resistance value change curve CRA(t2) overlap.

[0090] Also, as described above, the resistance value change curve CRA according to the first embodiment has a change region A-RA2 in the portion where the ink liquid surface distance SZ becomes the distance H2. That is, in the change region A-RA2 including the portion where the ink liquid surface distance SZ becomes the distance H2 in the resistance value change curve CRA, the resistance value of the combined resistance RG-A indicated by the resistance value change curve CRA changes greatly. Therefore, in the vertical axis direction of the graph shown in FIG. 13, a part of the change region A-RA2 of the resistance value change curve CRA(t1) and a part of the change region A-RA2 of the resistance value change curve CRA(t2) overlap.

[0091] FIG. 14 is an explanatory diagram for explaining the temperature change of the potential change curve CVA accompanying the temperature change of the ink IK in the ink tank TK according to the first embodiment.

[0092] Specifically, in FIG. 14, the potential change curve CVA when the temperature of the ink IK in the ink tank TK is the reference temperature t1 is represented as the potential change curve CVA(t1), and the potential change curve CVA when the temperature of the ink IK in the ink tank TK is the temperature t2 is represented as the potential change curve CVA(t2).

[0093] As shown in FIG. 14, when the temperature of the ink IK in the ink tank TK changes, the potential indicated by the potential change curve CVA also changes. Specifically, when the temperature of the ink IK in the ink tank TK changes from the reference temperature t1 to the temperature t2, the potential of the output signal Vout-A indicated by the potential change curve CVA also changes. That is, when the ink liquid surface distance SZ is the same value, the potential of the output signal Vout-A indicated by the potential change curve CVA(t1) and the potential of the output signal Vout-A indicated by the potential change curve CVA(t2) are different. Note that in FIG. 14, the case where the potential of the output signal Vout-A indicated by the potential change curve CVA changes to a small value as the temperature of the ink IK in the ink tank TK changes is illustrated, but the present invention is not limited to such a mode. The potential of the output signal Vout-A indicated by the potential change curve CVA may change to a large value as the temperature of the ink IK in the ink tank TK changes.

[0094] As described above, the potential change curve CVA according to the first embodiment has a change region A-VA1, which is a region where the potential of the output signal Vout-A indicated by the potential change curve CVA changes greatly in a portion where the ink liquid surface distance SZ is the distance H1. In the vertical axis direction of the graph shown in FIG. 14, the change region A-VA1 of the potential change curve CVA(t1) includes a portion where the output signal Vout-A becomes the threshold potential Vth1. That is, the change region A-VA1 of the potential change curve CVA(t1) intersects the straight line "Vout = Vth1" in the graph shown in FIG. 14. Further, since the change region A-VA1 is a region where the potential of the output signal Vout-A indicated by the potential change curve CVA changes greatly, in the vertical axis direction of the graph shown in FIG. 14, a part of the change region A-VA1 of the potential change curve CVA(t1) and a part of the change region A-VA1 of the potential change curve CVA(t2) overlap. If the temperature difference between the reference temperature t1 and the temperature t2 is within a predetermined temperature difference, the change region A-VA1 of the potential change curve CVA(t2) also includes a portion where the output signal Vout-A becomes the threshold potential Vth1. That is, if the temperature difference between the reference temperature t1 and the temperature t2 is within a predetermined temperature difference, the change region A-VA1 of the potential change curve CVA(t2) intersects the straight line "Vout = Vth1" in the graph shown in FIG. 14.

[0095] Here, the predetermined temperature difference may be, for example, the temperature difference between the temperature of the ink IK in the ink tank TK and the reference temperature t1 when the inkjet printer 100 is used in the limit use environment of the inkjet printer 100. Further, the predetermined temperature difference may be, for example, the temperature difference between the ambient temperature of the inkjet printer 100 and the reference temperature t1 when the inkjet printer 100 is used in the limit use environment of the inkjet printer 100. Further, the predetermined temperature difference may be, for example, the temperature difference between the temperature of the limit use environment of the ink IK and the reference temperature t1.

[0096] In the reference example as well, the change region A-VA1 of the potential change curve CVW(t1) intersects the straight line "Vout = Vth1" in the graph shown in FIG. 12, and the change region A-VA1 of the potential change curve CVW(t2) also intersects the straight line "Vout = Vth1" in the graph shown in FIG. 12.

[0097] As described above, the potential change curve CVA according to the first embodiment has a change region A-VA2, which is a region where the potential of the output signal Vout-A indicated by the potential change curve CVA changes greatly at the portion where the ink liquid surface distance SZ is the distance H2. In the vertical axis direction of the graph shown in FIG. 14, the change region A-VA2 of the potential change curve CVA(t1) includes the portion where the output signal Vout-A becomes the threshold potential Vth2. That is, the change region A-VA2 of the potential change curve CVA(t1) intersects the straight line "Vout = Vth2" in the graph shown in FIG. 14. Also, since the change region A-VA2 is a region where the potential of the output signal Vout-A indicated by the potential change curve CVA changes greatly, in the vertical axis direction of the graph shown in FIG. 14, a part of the change region A-VA2 of the potential change curve CVA(t1) and a part of the change region A-VA2 of the potential change curve CVA(t2) overlap. Therefore, if the temperature difference between the reference temperature t1 and the temperature t2 is within a predetermined temperature difference, the change region A-VA2 of the potential change curve CVA(t2) also includes the portion where the output signal Vout-A becomes the threshold potential Vth2. That is, if the temperature difference between the reference temperature t1 and the temperature t2 is within a predetermined temperature difference, the change region A-VA2 of the potential change curve CVA(t2) intersects the straight line "Vout = Vth2" in the graph shown in FIG. 14.

[0098] Therefore, according to the first embodiment, when the temperature of the ink IK in the ink tank TK is the reference temperature t1 and when it is the temperature t2, based on the potential of the output signal Vout-A being higher than the threshold potential Vth1, it is specified that the remaining amount of the ink IK in the ink tank TK is less than the ink amount corresponding to the distance H1, and based on the potential of the output signal Vout-A being higher than the threshold potential Vth2, it can be specified that the remaining amount of the ink IK in the ink tank TK is less than the ink amount corresponding to the distance H2. On the other hand, according to the reference example, similar to the first embodiment, when the temperature of the ink IK in the ink tank TK-W is the reference temperature t1 and when it is the temperature t2, based on the potential of the output signal Vout-A being higher than the threshold potential Vth1, it can be specified that the remaining amount of the ink IK in the ink tank TK is less than the ink amount corresponding to the distance H1. However, according to the reference example, unlike the first embodiment, when the temperature of the ink IK in the ink tank TK-W is the reference temperature t1 and when it is the temperature t2, based on the potential of the output signal Vout-A being higher than the threshold potential Vth2, the remaining amount of the ink IK in the ink tank TK cannot be specified. That is, according to the inkjet printer 100 according to the first embodiment, compared with the inkjet printer according to the reference example, it is possible to accurately detect the remaining amount of the ink IK in the ink tank TK based on the output signal Vout.

[0099] In this embodiment, a case has been exemplified and described in which due to the temperature change of the ink IK in the ink tank TK, the resistance value of the combined resistor RG changes, and as a result, the potential of the output signal Vout-A shown by the potential change curve CVA changes. However, the present invention is not limited to such a mode. This embodiment can be applied to any case where the potential of the output signal Vout-A shown by the potential change curve CVA fluctuates.

[0100] For example, according to the present embodiment, even when the potential of the output signal Vout-A indicated by the potential change curve CVA changes due to deterioration or denaturation of the ink IK in the ink tank TK, compared with the reference example, based on the output signal Vout, it is possible to accurately detect the remaining amount of the ink IK in the ink tank TK. Further, according to the present embodiment, even when the potential of the output signal Vout-A indicated by the potential change curve CVA changes due to noise being superimposed on the output signal Vout-A, compared with the reference example, based on the output signal Vout, it is possible to accurately detect the remaining amount of the ink IK in the ink tank TK.

[0101] <<1.5. Conclusion of the First Embodiment>> As described above, the inkjet printer 100 according to the present embodiment includes an ink tank TK that stores conductive ink IK, an electrode rod BT stored in the ink tank TK, an electrode rod B1 stored in the ink tank TK, an electrode rod B2 stored in the ink tank TK, and an output circuit 20 that is electrically connected to the electrode rods B1 and B2 and outputs an output signal Vout-A corresponding to the electrical signals from the electrode rods B1 and B2, and a control device 8 that specifies the remaining amount of the ink IK stored in the ink tank TK based on the output signal Vout-A. The electrode rod B1 contacts the ink IK stored in the ink tank TK when the ink tank TK stores an amount of ink IK equal to or greater than the ink amount corresponding to the distance H1. The electrode rod B2 contacts the ink IK stored in the ink tank TK when the ink tank TK stores an amount of ink IK equal to or greater than the ink amount corresponding to the distance H2. The electrode rod BT contacts the ink IK stored in the ink tank TK when the ink tank TK stores an amount of ink IK corresponding to the distance H1. This is the feature.

[0102] Thus, in the present embodiment, in addition to the electrode rods BT and B1, the ink tank TK houses an electrode rod B2 having a height different from that of the electrode rod B1. That is, in the present embodiment, when the ink amount in the ink tank TK is equal to or more than the ink amount corresponding to the distance H1 and less than the ink amount corresponding to the distance H2, the output circuit 20 outputs an output signal Vout-A according to the resistance value of the ink IK between the electrode rods BT and B1. When the ink amount in the ink tank TK is equal to or more than the ink amount corresponding to the distance H2, the output circuit 20 outputs an output signal Vout-A according to the resistance value of the combined resistance RG of the ink IK between the electrode rods BT and B1 and the ink IK between the electrode rods BT and B2. In the present embodiment, the control device 8 specifies the remaining amount of the ink IK housed in the ink tank TK based on the output signal Vout-A according to the electrical signals from the electrode rods B1 and B2. Therefore, according to the present embodiment, compared with the mode in the reference example where the electrode rods BT and B1 are housed in the ink tank TK-W and the remaining amount of the ink IK housed in the ink tank TK-W is specified based on the output signal Vout-W according to the electrical signal from the electrode rod B1, it is possible to increase the potential change of the output signal Vout-A output by the output circuit 20 in the vicinity where the ink amount in the ink tank TK becomes the ink amount corresponding to the distance H2. Therefore, according to the present embodiment, it is possible to accurately detect the remaining amount of the ink IK in the ink tank TK as compared with the reference example.

[0103] <<2. Second Embodiment>> Hereinafter, an inkjet printer according to the second embodiment will be described with reference to FIGS. 15 to 21. In each of the embodiments illustrated below, for elements whose operations and functions are the same as those in the first embodiment, the reference numerals used in the description of the first embodiment are reused, and the detailed description of each is omitted as appropriate.

[0104] <<2.1. Outline of the Inkjet Printer According to the Second Embodiment>> The inkjet printer according to the second embodiment differs from the inkjet printer 100 according to the first embodiment in that it includes an ink storage device 1B instead of the ink storage device 1A.

[0105] FIG. 15 is a circuit diagram for explaining the configuration of the ink storage device 1B.

[0106] As shown in FIG. 15, the ink storage device 1B differs from the ink storage device 1A according to the first embodiment in that it includes an ink amount detection circuit 2B instead of the ink amount detection circuit 2A. Further, the ink amount detection circuit 2B differs from the ink amount detection circuit 2A according to the first embodiment in that a resistor RK1 is provided between the detection terminal TnK1 and the node NK. That is, in the second embodiment, it is assumed that the resistance value of the first wiring path from the electrode bar B1 to the node NK via the detection wiring LK1, the detection terminal TnK1, and the resistor RK1 is higher than the resistance value of the second wiring path from the electrode bar B2 to the node NK via the detection wiring LK2 and the detection terminal TnK2. In this embodiment, the resistor RK1 is an example of a "resistive element".

[0107] In the second embodiment, the combined resistance RG in the electrical connection path from the electrode bar BT to the node NK is referred to as the combined resistance RG-B.

[0108] FIGS. 16 and 17 are circuit diagrams for explaining the combined resistance RG-B according to the second embodiment. Among them, FIG. 16 is a diagram showing the combined resistance RG-B when the ink liquid surface distance SZ is equal to or greater than the distance H1 and less than the distance H2. FIG. 17 is a diagram showing the combined resistance RG-B when the ink liquid surface distance SZ is equal to or greater than the distance H2.

[0109] When the ink liquid level distance SZ is equal to or greater than the distance H1 and less than the distance H2, the electrode rod BT and the electrode rod B1 are electrically connected by the ink IK, while the electrode rod BT and the electrode rod B2 are not electrically connected. Therefore, when the ink liquid level distance SZ is equal to or greater than the distance H1 and less than the distance H2, as shown in FIG. 16, the combined resistance RG-B is approximately the same as the combined resistance of the ink resistance RT1 and the resistance RK1 when the ink resistance RT1 and the resistance RK1 are connected in series. That is, when the combined resistance RG-B when the ink liquid level distance SZ is equal to or greater than the distance H1 and less than the distance H2 is referred to as the combined resistance RG1, the resistance value of the combined resistance RG1 is represented by the following formula (1). In the following formula, the symbol of each resistance is used as the resistance value of the corresponding resistance. RG1 = RT1+RK1 …(1)

[0110] When the ink liquid level distance SZ is equal to or greater than the distance H2, the electrode rod BT and the electrode rod B1 are electrically connected by the ink IK, and the electrode rod BT and the electrode rod B2 are electrically connected by the ink IK. Therefore, when the ink liquid level distance SZ is equal to or greater than the distance H2, as shown in FIG. 17, the combined resistance RG-B is approximately the same as the combined resistance of the ink resistance RT1, the ink resistance RT2, and the resistance RK1 when the resistance obtained by connecting the ink resistance RT1 and the resistance RK1 in series and the ink resistance RT2 are connected in parallel. That is, when the combined resistance RG-B when the ink liquid level distance SZ is equal to or greater than the distance H2 is referred to as the combined resistance RG2, the resistance value of the combined resistance RG2 is represented by the following formula (2). RG2 = {(RT1+RK1)*RT2}÷{RT1+RT2+RK1} …(2)

[0111] <<2.2. Relationship between Ink Liquid Level Distance and Combined Resistance and Output Signal>> FIG. 18 is an explanatory diagram for explaining the resistance value change curve CRB according to the second embodiment and the resistance value change curve CRA according to the first embodiment. Here, the resistance value change curve CRB is a curve showing the relationship between the resistance value of the combined resistor RG-B and the ink liquid surface distance SZ in the second embodiment. In FIG. 18, by setting the horizontal axis as the ink liquid surface distance SZ and the vertical axis as the resistance value of the combined resistor RG, the relationship between the ink liquid surface distance SZ and the resistance value of the combined resistor RG-B is represented as the resistance value change curve CRB, and the relationship between the ink liquid surface distance SZ and the resistance value of the combined resistor RG-A is represented as the resistance value change curve CRA.

[0112] As shown by the resistance value change curve CRB in FIG. 18, also in the second embodiment, similar to the first embodiment, when the ink liquid surface distance SZ is equal to or greater than the distance H1, the combined resistor RG-B has a smaller resistance value compared to the case where the ink liquid surface distance SZ is less than the distance H1. That is, in the present embodiment, the resistance value change curve CRB has a change region A-RB1 where the combined resistor RG-B changes significantly at the boundary between the case where the ink liquid surface distance SZ is less than the distance H1 and the case where the ink liquid surface distance SZ is equal to or greater than the distance H1.

[0113] Also, as shown by the resistance value change curve CRB in FIG. 18, also in the second embodiment, similar to the first embodiment, when the ink liquid surface distance SZ is equal to or greater than the distance H1 and less than the distance H2, the resistance value of the combined resistor RG-B decreases as the ink liquid surface distance SZ increases.

[0114] Also, as shown by the resistance value change curve CRB in FIG. 18, also in the second embodiment, similar to the first embodiment, when the ink liquid surface distance SZ is equal to or greater than the distance H2, the combined resistor RG-B has a smaller resistance value compared to the case where the ink liquid surface distance SZ is less than the distance H2. That is, in the second embodiment, the resistance value change curve CRB has a change region A-RB2 where the combined resistor RG-B changes significantly at the boundary between the case where the ink liquid surface distance SZ is less than the distance H2 and the case where the ink liquid surface distance SZ is equal to or greater than the distance H2.

[0115] Also, as shown by the resistance value change curve CRB in Fig. 18, also in the second embodiment, as in the first embodiment, when the ink liquid surface distance SZ is greater than or equal to the distance H2, as the ink liquid surface distance SZ increases, the resistance value of the combined resistance RG-B decreases.

[0116] As described above, the ink amount detection circuit 2A according to the first embodiment does not include the resistor RK1, whereas the ink amount detection circuit 2B according to the second embodiment includes the resistor RK1. For this reason, as shown in Fig. 18, the resistance value of the combined resistance RG-B indicated by the resistance value change curve CRB is higher than the resistance value of the combined resistance RG-A indicated by the resistance value change curve CRA.

[0117] Fig. 19 is an explanatory diagram for explaining the potential change curve CVB according to the second embodiment and the potential change curve CVA according to the first embodiment. Here, the potential change curve CVB is a curve showing the relationship between the output signal Vout output by the ink amount detection circuit 2B in the second embodiment and the ink liquid surface distance SZ. In Fig. 19, by setting the horizontal axis as the ink liquid surface distance SZ and the vertical axis as the potential of the output signal Vout, the relationship between the ink liquid surface distance SZ and the potential of the output signal Vout according to the second embodiment is represented as the potential change curve CVB, and the relationship between the ink liquid surface distance SZ and the potential of the output signal Vout-A according to the first embodiment is represented as the potential change curve CVA. Hereinafter, when distinction is necessary, the output signal Vout output by the ink amount detection circuit 2B in the second embodiment may be referred to as the output signal Vout-B.

[0118] As shown by the potential change curve CVB in Fig. 19, also in the second embodiment, as in the first embodiment, as the ink liquid surface distance SZ increases, the potential of the output signal Vout-B decreases.

[0119] As described above, the resistance value change curve CRB has the change regions A-RB1 and A-RB2. Therefore, as shown in FIG. 19, the potential change curve CVB also has the change regions A-VB1 and A-VB2 where the rate of change of the potential of the output signal Vout-B increases with respect to the change in the ink liquid surface distance SZ. Here, the change region A-VB1 is a region corresponding to the change region A-RB1, and is a region where the potential of the output signal Vout-B changes greatly at the boundary between the case where the ink liquid surface distance SZ is less than the distance H1 and the case where the ink liquid surface distance SZ is greater than or equal to the distance H1. The change region A-VB2 is a region corresponding to the change region A-RB2, and is a region where the potential of the output signal Vout-B changes greatly at the boundary between the case where the ink liquid surface distance SZ is less than the distance H2 and the case where the ink liquid surface distance SZ is greater than or equal to the distance H2.

[0120] As shown in FIG. 19, in the second embodiment, when the temperature of the ink IK in the ink tank TK is the reference temperature t1 and the ink liquid surface distance SZ in the ink tank TK is the distance H1, the potential indicated by the output signal Vout-B is referred to as the threshold potential Vth1. In the second embodiment, when the temperature of the ink IK in the ink tank TK is the reference temperature t1 and the ink liquid surface distance SZ in the ink tank TK is the distance H2, the potential indicated by the output signal Vout-B is referred to as the threshold potential Vth2.

[0121] Then, in the second embodiment, the control device 8 specifies the remaining amount of the ink IK stored in the ink tank TK based on the output signal Vout-B. Specifically, in the second embodiment, when the potential of the output signal Vout-B is higher than the threshold potential Vth1, the control device 8 specifies that the remaining amount of the ink IK in the ink tank TK is less than the ink amount corresponding to the distance H1, and when the potential of the output signal Vout-B is lower than the threshold potential Vth1, the control device 8 specifies that the remaining amount of the ink IK in the ink tank TK is more than the ink amount corresponding to the distance H1. Also, in the second embodiment, when the potential of the output signal Vout-B is higher than the threshold potential Vth2, the control device 8 specifies that the remaining amount of the ink IK in the ink tank TK is less than the ink amount corresponding to the distance H2, and when the potential of the output signal Vout-B is lower than the threshold potential Vth2, the control device 8 specifies that the remaining amount of the ink IK in the ink tank TK is more than the ink amount corresponding to the distance H2.

[0122] Note that the change amount of the combined resistance RG-A in the change region A-RA2 according to the first embodiment is referred to as the change amount GPA, and the change amount of the combined resistance RG-B in the change region A-RB2 according to the second embodiment is referred to as the change amount GPB. In this case, the change amount GPA is represented by the following formula (3) as an example, and the change amount GPB is represented by the following formula (4) as an example. GPA = RT1 - [{RT1 * RT2} ÷ {RT1 + RT2}] …(3) GPB = RG1 - RG2 = [RT1 + RK1] - [{(RT1 + RK1) * RT2} ÷ {RT1 + RT2 + RK1}] …(4)

[0123] Here, for the sake of convenience of explanation, it is assumed that "RT1 = RT2 = RT0". In this case, the change amount GPA is represented by the following formula (5) as an example, and the change amount GPB is represented by the following formula (6) as an example. GPA = (1 / 2) * RT0 ……(5) GPB = [RT0 2 + RK1 2+2*RT0*RK1]÷[2*RT0+RK1] …(6)

[0124] Then, the value obtained by subtracting the change amount GPA from the change amount GPB is a non-negative value, for example, as shown in the following formula (7). GPB - GPA = [2*RK1 2 +3*RT0*RK1] ÷[2*(2*RT0+RK1)] …(7)

[0125] That is, according to the second embodiment, since the ink amount detection circuit 2B includes the resistor RK1, the change amount of the combined resistor RG-B in the change region A-RB2 of the resistance value change curve CRB can be made larger than the change amount of the combined resistor RG-A in the change region A-RA2 of the resistance value change curve CRA. Therefore, according to the second embodiment, compared with the first embodiment, the change amount of the potential of the output signal Vout-B in the change region A-VB2 of the potential change curve CVB can be made larger than the change amount of the potential of the output signal Vout-A in the change region A-VA2 of the potential change curve CVA. That is, according to the second embodiment, compared with the first embodiment, in the vicinity where the ink amount in the ink tank TK corresponds to the ink amount at the distance H2, the potential change of the output signal Vout-B output by the output circuit 20 can be increased. Therefore, according to the second embodiment, compared with the first embodiment, it is possible to accurately detect the remaining amount of the ink IK in the ink tank TK.

[0126] In the second embodiment, it is preferable that the resistor RK1 has a resistance value larger than the maximum value of the resistance value of the ink resistance RT1 when the ink liquid surface distance SZ is equal to or greater than the distance H1. Further, in the second embodiment, it is preferable that the resistor RK1 has a resistance value larger than the maximum value of the resistance value of the ink resistance RT2 when the ink liquid surface distance SZ is equal to or greater than the distance H2. By adopting a resistor having a large resistance value as the resistor RK1 in the second embodiment, it is possible to increase the potential change of the output signal Vout-B output by the output circuit 20 in the vicinity where the ink amount in the ink tank TK becomes the ink amount corresponding to the distance H2.

[0127] FIG. 20 is an explanatory diagram for explaining the temperature change of the resistance value change curve CRB accompanying the temperature change of the ink IK in the ink tank TK according to the second embodiment.

[0128] Specifically, in FIG. 20, the resistance value change curve CRB when the temperature of the ink IK in the ink tank TK is the reference temperature t1 is represented as the resistance value change curve CRB(t1), and the resistance value change curve CRB when the temperature of the ink IK in the ink tank TK is the temperature t2 is represented as the resistance value change curve CRB(t2).

[0129] As shown in FIG. 20, when the temperature of the ink IK in the ink tank TK changes, the resistance value indicated by the resistance value change curve CRB also changes. Specifically, when the ink liquid surface distance SZ is the same value, the resistance value of the combined resistance RG-B indicated by the resistance value change curve CRB(t1) is different from the resistance value of the combined resistance RG-B indicated by the resistance value change curve CRB(t2).

[0130] As described above, the resistance value change curve CRB has a change region A-RB1 where the ink liquid surface distance SZ is the distance H1. That is, in the change region A-RB1 including the portion where the ink liquid surface distance SZ is the distance H1 in the resistance value change curve CRB, the resistance value of the combined resistance RG-B indicated by the resistance value change curve CRB changes greatly. For this reason, in the vertical axis direction of the graph shown in FIG. 20, a part of the change region A-RB1 of the resistance value change curve CRB(t1) and a part of the change region A-RB2 of the resistance value change curve CRB(t2) overlap.

[0131] Also, as described above, the resistance value change curve CRB has a change region A-RB2 where the ink liquid surface distance SZ is the distance H2. That is, in the change region A-RB2 including the portion where the ink liquid surface distance SZ is the distance H2 in the resistance value change curve CRB, the resistance value of the combined resistance RG-B indicated by the resistance value change curve CRB changes greatly. For this reason, in the vertical axis direction of the graph shown in FIG. 20, a part of the change region A-RB2 of the resistance value change curve CRB(t1) and a part of the change region A-RB2 of the resistance value change curve CRB(t2) overlap.

[0132] FIG. 21 is an explanatory diagram for explaining the temperature change of the potential change curve CVB accompanying the temperature change of the ink IK in the ink tank TK according to the second embodiment.

[0133] Specifically, in FIG. 21, the potential change curve CVB when the temperature of the ink IK in the ink tank TK is the reference temperature t1 is represented as the potential change curve CVB(t1), and the potential change curve CVB when the temperature of the ink IK in the ink tank TK is the temperature t2 is represented as the potential change curve CVB(t2).

[0134] As shown in FIG. 21, when the temperature of the ink IK in the ink tank TK changes, the potential indicated by the potential change curve CVB also changes. Specifically, when the ink liquid surface distance SZ is the same value, the potential of the output signal Vout-B indicated by the potential change curve CVB(t1) and the potential of the output signal Vout-B indicated by the potential change curve CVB(t2) are different.

[0135] As described above, the potential change curve CVB has a change region A-VB1, which is a region where the potential of the output signal Vout-B indicated by the potential change curve CVB changes greatly at the portion where the ink liquid surface distance SZ becomes the distance H1. The change region A-VB1 of the potential change curve CVB(t1) intersects the straight line "Vout = Vth1" in the graph shown in FIG. 21. Further, since the change region A-VB1 is a region where the potential of the output signal Vout-B indicated by the potential change curve CVB changes greatly, in the vertical axis direction of the graph shown in FIG. 21, a part of the change region A-VB1 of the potential change curve CVB(t1) and a part of the change region A-VB1 of the potential change curve CVB(t2) overlap. And if the temperature difference between the reference temperature t1 and the temperature t2 is within a predetermined temperature difference, the change region A-VB1 of the potential change curve CVB(t2) intersects the straight line "Vout = Vth1" in the graph shown in FIG. 21.

[0136] As described above, the potential change curve CVB has a change region A-VB2, which is a region where the potential of the output signal Vout-B indicated by the potential change curve CVB changes greatly at the portion where the ink liquid surface distance SZ becomes the distance H2. The change region A-VB2 of the potential change curve CVB(t1) intersects the straight line "Vout = Vth2" in the graph shown in FIG. 21. Further, since the change region A-VB2 is a region where the potential of the output signal Vout-B indicated by the potential change curve CVB changes greatly, in the vertical axis direction of the graph shown in FIG. 21, a part of the change region A-VB2 of the potential change curve CVB(t1) and a part of the change region A-VB2 of the potential change curve CVB(t2) overlap. Therefore, if the temperature difference between the reference temperature t1 and the temperature t2 is within a predetermined temperature difference, the change region A-VB2 of the potential change curve CVB(t2) intersects the straight line "Vout = Vth2" in the graph shown in FIG. 21.

[0137] Therefore, according to the second embodiment, when the temperature of the ink IK in the ink tank TK is the reference temperature t1 and when it is the temperature t2, based on the fact that the potential of the output signal Vout-B is higher than the threshold potential Vth1, it is specified that the remaining amount of the ink IK in the ink tank TK is less than the ink amount corresponding to the distance H1, and based on the fact that the potential of the output signal Vout-B is higher than the threshold potential Vth2, it can be specified that the remaining amount of the ink IK in the ink tank TK is less than the ink amount corresponding to the distance H2. That is, according to the inkjet printer 100 according to the second embodiment, compared with the inkjet printer according to the above-described reference example, it becomes possible to accurately detect the remaining amount of the ink IK in the ink tank TK based on the output signal Vout.

[0138] Note that, similar to the first embodiment, the second embodiment can be applied to any case where the potential of the output signal Vout-B fluctuates, in addition to the case where the potential of the output signal Vout-B changes due to the temperature change of the ink IK in the ink tank TK.

[0139] <<2.3. Conclusion of the Second Embodiment>> As described above, the inkjet printer according to the second embodiment includes an ink tank TK that stores conductive ink IK, an electrode bar BT stored in the ink tank TK, an electrode bar B1 stored in the ink tank TK, an electrode bar B2 stored in the ink tank TK, and an output circuit 20 that is electrically connected to the electrode bars B1 and B2 and outputs an output signal Vout-B corresponding to the electrical signals from the electrode bars B1 and B2, and a control device 8 that specifies the remaining amount of the ink IK stored in the ink tank TK based on the output signal Vout-B. The electrode bar B1 contacts the ink IK stored in the ink tank TK when the ink tank TK stores an amount of ink IK equal to or greater than the ink amount corresponding to the distance H1. The electrode bar B2 contacts the ink IK stored in the ink tank TK when the ink tank TK stores an amount of ink IK equal to or greater than the ink amount corresponding to the distance H2. The electrode bar BT contacts the ink IK stored in the ink tank TK when the ink tank TK stores an amount of ink IK corresponding to the distance H1. The resistance value of the first wiring path from the electrode bar B1 to the output circuit 20 is higher than the resistance value of the second wiring path from the electrode bar B2 to the output circuit 20.

[0140] Therefore, according to the present embodiment, compared with the mode in which the electrode bar BT and the electrode bar B1 are stored in the ink tank TK-W and the remaining amount of the ink IK stored in the ink tank TK-W is specified based on the output signal Vout-W corresponding to the electrical signal from the electrode bar B1 as in the reference example, it is possible to increase the potential change of the output signal Vout-B output by the output circuit 20 in the vicinity where the ink amount in the ink tank TK becomes the ink amount corresponding to the distance H2. Therefore, according to the present embodiment, it is possible to accurately detect the remaining amount of the ink IK in the ink tank TK as compared with the reference example.

[0141] Also, according to the present embodiment, since the resistance value of the first wiring path is higher than that of the second wiring path, the potential change of the output signal Vout-B output by the output circuit 20 can be increased in the vicinity where the ink amount in the ink tank TK becomes the ink amount corresponding to the distance H2, as compared with the case where the resistance value of the first wiring path is less than or equal to the resistance value of the second wiring path. Therefore, according to the present embodiment, it is possible to accurately detect the remaining amount of the ink IK in the ink tank TK as compared with the first embodiment.

[0142] Further, in the inkjet printer according to the second embodiment, it is characterized in that a resistor RK1 is arranged in the first wiring path.

[0143] Therefore, according to the present embodiment, it is possible to accurately detect the remaining amount of the ink IK in the ink tank TK as compared with the aspect where the resistor RK1 is not arranged in the first wiring path.

[0144] Further, in the inkjet printer according to the second embodiment, it may be characterized in that the resistance value of the resistor RK1 is higher than the resistance value of the ink resistance RT1 between the electrode rod BT and the electrode rod B1.

[0145] Therefore, according to the present embodiment, it is possible to accurately detect the remaining amount of the ink IK in the ink tank TK as compared with the case where the resistance value of the resistor RK1 is less than or equal to the resistance value of the ink resistance RT1.

[0146] Further, in the inkjet printer according to the second embodiment, it may be characterized in that it is possible to add the ink IK from the supply port 12 to the ink tank TK, and the ink amount corresponding to the distance H2 is an amount based on the maximum amount of the ink IK that can be accommodated in the ink tank TK.

[0147] In this case, when adding the ink IK to the ink tank TK, it is possible to confirm in advance the possibility of the ink IK overflowing from the ink tank TK.

[0148] Also, in the inkjet printer according to the second embodiment, it may be characterized in that the ink amount corresponding to the distance H1 is an amount based on the minimum amount of the ink IK in the ink tank TK.

[0149] In this case, it becomes possible to confirm in advance the depletion of the ink IK in the ink tank TK.

[0150] <<3. Modification Example>> Each of the embodiments exemplified above can be variously modified. Specific modification modes are exemplified below. Two or more modes arbitrarily selected from the following examples can be appropriately combined within a range that does not conflict with each other.

[0151] <<3.1. Modification Example 1>> In the above-described first and second embodiments, in the ink tank TK, an aspect in which three electrode rods, namely, the electrode rod BT, the electrode rod B1, and the electrode rod B2, are accommodated has been exemplified and described. However, the present invention is not limited to such an aspect. Two electrode rods may be accommodated in the ink tank, or four or more electrode rods may be accommodated.

[0152] FIG. 22 is a circuit diagram for explaining the configuration of the ink storage device 1C. Note that the inkjet printer according to this modification example is different from the inkjet printer 100 according to the first embodiment in that it includes the ink storage device 1C instead of the ink storage device 1A.

[0153] As shown in FIG. 22, the ink storage device 1C is different from the ink storage device 1 according to the first embodiment in that it includes an ink amount detection circuit 2C instead of the ink amount detection circuit 2A and includes an ink tank TK-C instead of the ink tank TK.

[0154] Among these, the ink tank TK-C is different from the ink tank TK according to the first embodiment in that it includes an electrode bar B3 in addition to the electrode bar BT, the electrode bar B1, and the electrode bar B2. Hereinafter, when the ink IK is stored in the ink tank TK-C and the electrode bars BT and B3 come into contact with the ink IK stored in the ink tank TK-C, the electrical resistance of the ink IK that electrically connects the electrode bars BT and B3 is referred to as the ink resistance RT3.

[0155] Further, the ink amount detection circuit 2C is different from the ink amount detection circuit 2 according to the first embodiment in that it includes a detection terminal TnK3 and a resistor RK3. The detection terminal TnK3 is electrically connected to the electrode bar B3 via a detection wiring LK3. The resistor RK3 is disposed between the detection terminal TnK3 and the node NK and electrically connects the detection terminal TnK3 and the node NK.

[0156] In this modification, it is assumed that the resistance value of the resistor RK3 is lower than the resistance value of the resistor RK1. That is, in this modification, the resistance value of the third wiring path from the electrode bar B3 to the node NK via the detection wiring LK3, the detection terminal TnK3, and the resistor RK3 is lower than the resistance value of the first wiring path from the electrode bar B1 to the node NK via the detection wiring LK1, the detection terminal TnK1, and the resistor RK1, and is higher than the resistance value of the second wiring path from the electrode bar B2 to the node NK via the detection wiring LK2 and the detection terminal TnK2.

[0157] FIG. 23 is a configuration diagram showing an example of the configuration of the ink tank TK-C.

[0158] As shown in FIG. 23, the electrode bar B1 has a conductive electrode component G3 extending in the Z1 direction and a conductive connection portion G3t extending in the Z1 direction and electrically connecting the electrode component G3 and the detection wiring LK3. In this modification, it is assumed that the electrode bar B3 is provided such that the distance in the Z-axis direction from the end portion of the electrode bar B3 in the Z1 direction to the bottom surface TM of the ink tank TK is the distance H3. Here, the distance H3 is a distance that satisfies "H1 < H3 < H2".

[0159] Further, in this modified example, as an example, it is assumed that the electrode bar B3 is provided such that the distance in the Z-axis direction from the end portion of the electrode component G3 in the Z2 direction to the bottom surface TM of the ink tank TK is the distance HF.

[0160] As shown in FIG. 23, when ink IK exists between the electrode bar BT and the electrode bar B3, that is, when the ink liquid surface distance SZ is equal to or greater than the distance H3, the electrode bar BT and the electrode bar B3 are electrically connected by the ink IK. Therefore, when the ink liquid surface distance SZ is equal to or greater than the distance H3, the electrode bar BT and the electrode bar B3 are electrically connected by the ink IK having the ink resistance RT3. Note that, in the present embodiment, the amount of ink in the ink tank TK such that the ink liquid surface distance SZ is equal to the distance H3 is an example of the "third amount".

[0161] Note that, in this modified example, the electrical resistance in the electrical connection path from the electrode bar BT to the node NK is referred to as the combined resistance RG-C. When the electrical resistances of the detection wiring LK1, the detection wiring LK2, the detection wiring LK3, the electrode bar B1, the electrode bar B2, and the electrode bar B3 are sufficiently small, the combined resistance RG-C will have substantially the same resistance value as the combined resistance of the ink resistance RT1, the ink resistance RT2, the ink resistance RT3, the resistance RK1, and the resistance RK3.

[0162] As described above, the inkjet printer according to Modification 1 includes an ink tank TK-C that stores conductive ink IK, an electrode bar BT stored in the ink tank TK-C, an electrode bar B1 stored in the ink tank TK-C, an electrode bar B2 stored in the ink tank TK-C, an electrode bar B3 stored in the ink tank TK-C, and an output circuit 20 that is electrically connected to the electrode bars B1, B2, and B3 and outputs an output signal Vout corresponding to the electrical signals from the electrode bars B1, B2, and B3, and a control device 8 that specifies the remaining amount of the ink IK stored in the ink tank TK-C based on the output signal Vout. The electrode bar B1 contacts the ink IK stored in the ink tank TK-C when the ink tank TK-C stores an amount of ink IK equal to or greater than the ink amount corresponding to the distance H1. The electrode bar B2 contacts the ink IK stored in the ink tank TK-C when the ink tank TK-C stores an amount of ink IK equal to or greater than the ink amount corresponding to the distance H2. The electrode bar B3 contacts the ink IK stored in the ink tank TK-C when the ink tank TK-C stores an amount of ink IK equal to or greater than the ink amount corresponding to the distance H3. The electrode bar BT contacts the ink IK stored in the ink tank TK-C when the ink tank TK-C stores an amount of ink IK corresponding to the distance H1. The ink amount corresponding to the distance H3 is greater than the ink amount corresponding to the distance H1 and less than the ink amount corresponding to the distance H2. The resistance value of the third wiring path from the electrode bar B3 to the output circuit 20 is lower than the resistance value of the first wiring path from the electrode bar B1 to the output circuit 20 and higher than the resistance value of the second wiring path from the electrode bar B2 to the output circuit 20.

[0163] Therefore, according to Modification 1, as in the reference example, in the ink tank TK-W, the electrode rod BT and the electrode rod B1 are accommodated, and based on the output signal Vout-W corresponding to the electrical signal from the electrode rod B1, compared with the aspect of specifying the remaining amount of the ink IK accommodated in the ink tank TK-W, in the vicinity where the ink amount in the ink tank TK-C becomes the ink amount corresponding to the distance H3 and in the vicinity where the ink amount in the ink tank TK-C becomes the ink amount corresponding to the distance H2, it is possible to increase the potential change of the output signal Vout output by the output circuit 20. Therefore, according to Modification 1, compared with the reference example, it is possible to accurately detect the remaining amount of the ink IK in the ink tank TK-C.

[0164] Also, according to Modification 1, compared with the first embodiment, in the vicinity where the ink amount in the ink tank TK-C becomes the ink amount corresponding to the distance H3, it is possible to increase the potential change of the output signal Vout output by the output circuit 20. Therefore, according to Modification 1, compared with the first embodiment, it is possible to accurately detect the remaining amount of the ink IK in the ink tank TK-C.

[0165] <<3.2. Modification 2>> In the above-described first embodiment, second embodiment, and Modification 1, the case where the ink storage devices 1A to 1C include the output circuit 20 has been illustrated and described, but the present invention is not limited to such an aspect. The ink storage device 1 may be any device that includes an output circuit 20 capable of detecting the remaining amount of the ink IK accommodated in the ink tank TK based on an electrical signal from one or more electrode rods provided in the ink tank TK.

[0166] FIG. 24 is a circuit diagram showing an example of the configuration of an ink storage device 1Q included in an inkjet printer according to Modification 2. Note that the inkjet printer according to Modification 2 differs from the inkjet printer 100 according to the first embodiment in that it includes an ink storage device 1Q instead of the ink storage device 1A. Further, the ink storage device 1Q differs from the ink storage device 1A according to the first embodiment in that it includes an ink amount detection circuit 2Q instead of the ink amount detection circuit 2A.

[0167] As shown in FIG. 24, the ink amount detection circuit 2Q includes an input terminal TnN, a detection terminal TnK1, a detection terminal TnK2, a reference potential connection terminal TnT, an output terminal TnS, a resistor RK1, a capacitor CQ1, and an output circuit 20Q including a node NK.

[0168] An input signal Vin is input to the input terminal TnN. The detection terminal TnK1 is electrically connected to the electrode rod B1 via the detection wiring LK1. The detection terminal TnK2 is electrically connected to the electrode rod B2 via the detection wiring LK2. The reference potential connection terminal TnT is electrically connected to the electrode rod BT via the reference potential connection wiring LT. The output terminal TnS outputs an output signal Vout. One end of the resistor RK1 is electrically connected to the node NK, and the other end is electrically connected to the node NQ1. One of the two electrodes of the capacitor CQ1 is electrically connected to the reference potential connection terminal TnT, and the other electrode is electrically connected to a wiring set to the ground potential.

[0169] The output circuit 20Q includes a node NK, a node NQ1, a node NQ2, a node NQ3, an input resistor RN, a resistor RQ1, a resistor RQ2, a capacitor CQ2, and a switch SWQ.

[0170] The node NK is electrically connected to one end of the resistor RK1, one end of the input resistor RN, and further, the detection terminal TnK2. Node NQ1 is electrically connected to the other end of the input resistor RN, and is also electrically connected to the input terminal TnN. An input signal Vin is supplied through the input terminal TnN.

[0171] Switch SWQ has two input terminals, one output terminal, and one control terminal. Of the two input terminals of switch SWQ, one input terminal is electrically connected to node NK, and the other input terminal is electrically connected to one end of resistor RQ1. The output terminal of switch SWQ is electrically connected to node NQ2. An input signal Vin is supplied to the control terminal of switch SWQ through node NQ1.

[0172] In this modified example, the input signal Vin is a signal set to either a high level or a low level signal level. And in this modified example, when the input signal Vin supplied to switch SWQ is at a low level, switch SWQ electrically connects the output terminal of switch SWQ and one of the two input terminals of switch SWQ. That is, in this modified example, when the input signal Vin supplied to switch SWQ is at a low level, switch SWQ electrically connects node NK and node NQ2. Also, in this modified example, when the input signal Vin supplied to switch SWQ is at a high level, switch SWQ electrically connects the output terminal of switch SWQ and the other of the two input terminals of switch SWQ. That is, in this modified example, when the input signal Vin supplied to switch SWQ is at a high level, switch SWQ electrically connects one end of resistor RQ1 and node NQ2.

[0173] One end of resistor RQ1 is electrically connected to the other of the two input terminals of switch SWQ, and the other end is electrically connected to a wiring set to a ground potential. One end of resistor RQ2 is electrically connected to node NQ2, and the other end is electrically connected to node NQ3. The capacitance CQ2 has two electrodes. One of the electrodes is electrically connected to the node NQ3, and the other electrode is electrically connected to a wiring set to the ground potential. Note that the resistor RQ2 and the capacitance CQ2 function as a low-pass filter. The output terminal TnS is electrically connected to the node NQ3 and outputs an output signal Vout indicating the potential of the node NQ3.

[0174] FIG. 25 is a timing chart for explaining various signals flowing through the ink amount detection circuit 2Q.

[0175] As shown in FIG. 25, in this modification, it is assumed that the operation period of the ink amount detection circuit 2Q is divided into a plurality of unit periods TQ. And in this modification, it is assumed that each unit period TQ is divided into a control period TP1 and a control period TP2.

[0176] The input signal Vin is set to a high level during the control period TP1 within the unit period TQ and set to a low level during the control period TP2 within the unit period TQ.

[0177] The signal VQK is a signal indicating the potential of the node NK. Hereinafter, when the ink IK stored in the ink tank TK is less than the remaining ink amount corresponding to the distance H1, that is, when the ink IK in the ink tank TK is depleted, the signal VQK is referred to as the signal VQK-E. Also, when the ink IK stored in the ink tank TK is equal to or more than the remaining ink amount corresponding to the distance H2, that is, when the ink IK in the ink tank TK is abundant, the signal VQK is referred to as the signal VQK-F.

[0178] When the ink IK in the ink tank TK is depleted, the electrode rod BT and the electrode rod B1 are not electrically connected, and the electrode rod BT and the electrode rod B2 are not electrically connected. Therefore, the signal VQK-E shows a waveform in the shape linked to the input signal Vin. Specifically, the signal VQK-E rises from the low level to the high level with a delay of time TQK-E compared to the timing when the input signal Vin rises from the low level to the high level, and falls from the high level to the low level with a delay of time TQK-E compared to the timing when the input signal Vin falls from the high level to the low level. Here, the time TQK-E is shorter than the time length of the control period TP1 and shorter than the time length of the control period TP2, and is the time for charging the capacitances parasitic on the detection wiring LK1, the detection wiring LK2, the electrode rod B1, and the electrode rod B2, etc.

[0179] When the ink IK in the ink tank TK[m] is abundant, the electrode rod BT and the electrode rod B1 are electrically connected, and the electrode rod BT and the electrode rod B2 are electrically connected. Therefore, the signal VQK-F shows a waveform that smoothes the input signal Vin. Specifically, the signal VQK-F rises from the low level to the high level with a delay of time TQK-F compared to the timing when the input signal Vin rises from the low level to the high level, and falls from the high level to the low level with a delay of time TQK-F compared to the timing when the input signal Vin falls from the high level to the low level. Here, the time TQK-F is longer than the time TQK-E, and is the time for charging the capacitances parasitic on the detection wiring LK1, the detection wiring LK2, the electrode rod B1, and the electrode rod B2, etc., in addition to the capacitances parasitic on the reference potential connection wiring LT and the electrode rod BT, etc., and the capacitance CQ1.

[0180] The signal VQ2 is a signal indicating the potential of the node NQ2. Hereinafter, when the ink IK in the ink tank TK is depleted and the ink liquid level distance SZ in the ink tank TK is less than the distance H1, the signal VQ2 is referred to as the signal VQ2-E. Also, when the ink IK in the ink tank TK is abundant and the ink liquid level distance SZ in the ink tank TK is greater than or equal to the distance H2, the signal VQ2 is referred to as the signal VQ2-F.

[0181] As described above, in the control period TP1 when the input signal Vin is at a high level, the switch SWQ electrically connects the node NQ2 and one end of the resistor RQ1. Therefore, in the control period TP1, the signal VQ2 is set to a low level.

[0182] Also, in the control period TP2 when the input signal Vin is at a low level, the switch SWQ electrically connects the node NQ2 and the node NK. Therefore, in the control period TP2, the signal VQ2-E shows a waveform shaped such that it takes time TQK-E to fall from a high level to a low level. Also, in the control period TP2, the signal VQ2-F shows a waveform shaped such that it takes time TQK-F to fall from a high level to a low level.

[0183] The signal VQ3 is a signal indicating the potential of the node NQ3. Hereinafter, when the ink IK in the ink tank TK is depleted and the ink liquid level distance SZ in the ink tank TK is less than the distance H1, the signal VQ3 is referred to as the signal VQ3-E. Also, when the ink IK in the ink tank TK is abundant and the ink liquid level distance SZ in the ink tank TK is greater than or equal to the distance H2, the signal VQ3 is referred to as the signal VQ3-F.

[0184] As described above, the resistor RQ2 and the capacitor CQ2 function as a low-pass filter. Therefore, the signal VQ3 becomes a signal having a waveform obtained by removing the high-frequency component from the signal VQ2. And, as described above, the time TQK-F is longer than the time TQK-E. Therefore, the signal VQ3-F becomes a higher potential than the signal VQ3-E. That is, in this modification example, the ink amount detection circuit 2Q outputs a high-potential output signal Vout when the ink IK in the ink tank TK is abundant and the ink liquid surface distance SZ in the ink tank TK is equal to or greater than the distance H2, as compared with the case where the ink IK in the ink tank TK is depleted and the ink liquid surface distance SZ in the ink tank TK is less than the distance H1.

[0185] <<3.3. Modification Example 3>> In the above-described first embodiment, second embodiment, modification example 1, and modification example 2, the case where M ink amount detection circuits 2 corresponding one-to-one to M ink tanks TK[1] to TK[M] are provided in the ink storage device 1 has been exemplified and described. However, the present invention is not limited to such an aspect. The ink storage device 1 may be provided with fewer than M ink amount detection circuits 2.

[0186] For example, the ink storage device 1 may be provided with one ink amount detection circuit 2. In this case, the ink amount detection circuit 2 may, for example, divide the operation period of the ink amount detection circuit 2 into M unit operation periods, and detect the remaining amount of the ink IK stored in the ink tank TK[m] in the m-th unit operation period. Specifically, the ink amount detection circuit 2 may be configured to switch the ink tank TK[m] to which the ink amount detection circuit 2 is connected for each unit operation period.

[0187] <<3.4. Modification Example 4>> In the above-described first embodiment, second embodiment, and modification examples 1 to 3, the electrode rod B1 may be configured without having the connection portion G1t. In this case, the electrode rod B1 may have a configuration in which the electrode component G1 is connected to the detection wiring LK1. The same applies to the electrode rod B2, the electrode rod B3, and the electrode rod BT.

[0188] <<3.5. Modification Example 5>> In the above-described first embodiment, second embodiment, and modification examples 1 to 4, a serial inkjet printer that reciprocates a storage case 921 equipped with a liquid ejection head HU in the main scanning direction MH1 has been exemplified. However, the present invention is not limited to such a mode. The inkjet printer may be a line-type liquid ejection device including a liquid ejection head HU capable of ejecting ink IK over the entire width of the medium PP.

[0189] <<3.6. Modification Example 6>> In the above-described first embodiment, second embodiment, and modification examples 1 to 5, the liquid ejection device exemplified and described by using an inkjet printer can be adopted in various devices such as a facsimile machine and a copying machine in addition to a device dedicated to printing. However, the application of the liquid ejection device of the present invention is not limited to printing. For example, a liquid ejection device that ejects a colorant solution is used as a manufacturing device for forming a color filter of a liquid crystal display device. Further, a liquid ejection device that ejects a conductive material solution is used as a manufacturing device for forming wirings and electrodes of a wiring board.

Explanation of Reference Numerals

[0190] 1A... Ink storage device, 2A... Ink amount detection circuit, 8... Control device, 20... Output circuit, 100... Inkjet printer, BT... Electrode bar, B1... Electrode bar, B2... Electrode bar, TK... Ink tank, RK1... Resistor.

Claims

1. A storage container for storing a conductive liquid, A reference electrode stored in the storage container, A first electrode stored in the storage container, A second electrode stored in the storage container, An output unit electrically connected to the first electrode and the second electrode, and outputting an output signal according to the electrical signals from the first electrode and the second electrode, An identifying unit for identifying the remaining amount of the liquid stored in the storage container based on the output signal, Comprising, When the storage container stores a liquid in an amount equal to or greater than a first amount, the first electrode contacts the liquid stored in the storage container, When the storage container stores a liquid in an amount equal to or greater than a second amount, which is greater than the first amount, the second electrode contacts the liquid stored in the storage container, When the storage container stores a liquid in an amount equal to the first amount, the reference electrode contacts the liquid stored in the storage container, The resistance value of the first wiring path from the first electrode to the output circuit, Is higher than the resistance value of the second wiring path from the second electrode to the output circuit, A liquid discharge device characterized by the above.

2. A resistance element is arranged in the first wiring path, The liquid discharge device according to claim 1, characterized by the above.

3. The resistance value of the resistance element is higher than the resistance value between the reference electrode and the first electrode, The liquid discharge device according to claim 2, characterized by the above.

4. It is possible to add liquid to the storage container, The second amount is an amount based on the maximum amount of liquid that can be stored in the storage container, The liquid discharge device according to claim 1, characterized by the above.

5. The first amount is an amount based on the minimum amount of liquid in the storage container, The liquid discharge device according to claim 1, characterized by the above.

6. Comprising a third electrode stored in the storage container, The output unit is electrically connected to the third electrode and outputs an output signal according to the electrical signal from the third electrode, When the storage container stores a liquid in an amount equal to or greater than a third amount, which is greater than the first amount and less than the second amount, the third electrode contacts the liquid stored in the storage container, The resistance value of the third wiring path from the third electrode to the output circuit, Is lower than the resistance value of the first wiring path from the first electrode to the output circuit, Is higher than the resistance value of the second wiring path from the second electrode to the output circuit, The liquid discharge device according to claim 1, characterized by the above.

7. A storage container for storing a conductive liquid, The reference electrode housed in the storage container, The first electrode housed in the storage container, The second electrode housed in the storage container, Electrically connected to the first electrode and the second electrode, An output unit that outputs an output signal according to an electrical signal from the first electrode and the second electrode, Comprising, When the first electrode is in contact with the liquid contained in the storage container when the storage container contains a liquid in an amount equal to or greater than a first amount, When the second electrode is in contact with the liquid contained in the storage container when the storage container contains a liquid in an amount equal to or greater than a second amount, which is greater than the first amount, When the reference electrode is in contact with the liquid contained in the storage container when the storage container contains the liquid in the first amount, The resistance value of the first wiring path from the first electrode to the output circuit, Is higher than the resistance value of the second wiring path from the second electrode to the output circuit, A liquid storage device characterized by this.

8. A resistance element is arranged in the first wiring path, The liquid storage device according to claim 7, characterized by this.

9. The resistance value of the resistance element is higher than the resistance value between the reference electrode and the first electrode, The liquid storage device according to claim 8, characterized by this.

10. It is possible to add liquid to the storage container, The second amount is an amount based on the maximum amount of liquid that can be stored in the storage container, The liquid storage device according to claim 7, characterized by this.

11. The first amount is an amount based on the minimum amount of liquid in the storage container, The liquid storage device according to claim 7, characterized by this.

12. Comprising a third electrode housed in the storage container, The output unit, Electrically connected to the third electrode and outputting an output signal according to an electrical signal from the third electrode, The third electrode, When the storage container contains a liquid in an amount equal to or greater than a third amount, which is greater than the first amount and less than the second amount, the third electrode is in contact with the liquid contained in the storage container, The resistance value of the third wiring path from the third electrode to the output circuit, Is lower than the resistance value of the first wiring path from the first electrode to the output circuit, Higher than the resistance value of the second wiring path from the second electrode to the output circuit, The liquid storage device according to claim 7, characterized by this.

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