Load detection device and detection circuit

Abstract

A load detection device (3) is provided with: a load sensor (1) provided with an element part in which the capacitance varies in accordance with a load; and a detection circuit (2) that detects the capacitance of the element part. The detection circuit (2) is provided with: a potential application unit (100) that applies a predetermined potential to the two electrodes of the element unit; a current measurement unit (200) that measures the amount of electricity (current) that changes due to the charging or discharging of the electric charge to the element unit; and a control unit (300). The control unit (300): acquires a charge amount (Qm) on the basis of a current (Im) measured in a first mode in which different potentials are applied to the two electrodes; acquiring an electric charge amount (Qref) from a current (Iref) measured in a second mode in which the same potential is applied to the two electrodes; and detecting the capacitance of the element unit on the basis of the difference between the charge amount (Qm) and the charge amount (Qref).

Description

Technical Field

[0001] The present invention relates to a load detection device for detecting a load based on a change in electrostatic capacitance, and a detection circuit for detecting electrostatic capacitance from a component portion having a predetermined electrostatic capacitance. Background Art

[0002] Load sensors are widely used in the fields of industrial equipment, robots, and vehicles. In recent years, with the development of computer control technology and the improvement of design, the development of electronic devices such as humanoid robots and automobile interior decorations that make rich use of free-form surfaces is advancing. Accordingly, it is sought to install high-performance load sensors on each free-form surface.

[0003] The following patent document 1 describes a device for detecting the electrostatic capacitance of an electrostatic capacitance type sensor. In this device, a voltage is applied to a component part as a measurement object via a resistor. The electrostatic capacitance of the component part as a measurement object is detected based on the change in the voltage after the resistor. Specifically, the voltage value after the resistor is measured at a predetermined timing during the voltage application, and the electrostatic capacitance of the component part as a measurement object is calculated based on the voltage value. Furthermore, the load applied to the component part as a measurement object is calculated based on the calculated electrostatic capacitance.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2021-81209 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] However, in the above method, the parasitic capacitance and parasitic inductance of wiring and other components affect the change of the voltage at the subsequent stage of the resistor. Therefore, the calculated electrostatic capacitance includes an error component, and the detection accuracy of the load is reduced due to the error component.

[0009] In view of the above problems, an object of the present invention is to provide a load detection device and a detection circuit capable of detecting the electrostatic capacitance of a component portion with high accuracy.

[0010] Solutions for solving problems

[0011] A first aspect of the present invention relates to a load detection device. The load detection device according to this aspect comprises: a load sensor having an element portion whose electrostatic capacitance changes according to a load; and a detection circuit that detects the electrostatic capacitance of the element portion. The detection circuit comprises: a potential applying portion that applies a predetermined potential to two electrodes of the element portion; a measuring portion that measures the amount of electricity that changes due to charging or discharging of the electric charge on the element portion; and a control portion. The control portion performs the following processing: obtaining a first value based on the amount of electricity measured in a first mode in which different potentials are applied to the two electrodes; obtaining a second value based on the amount of electricity measured in a second mode in which the same potential is applied to the two electrodes; and detecting the electrostatic capacitance of the element portion based on the difference between the first value and the second value.

[0012] According to the load detection device involved in this method, the first value reflects the amount of charge accumulated in the component part and the amount of unnecessary charge generated by parasitic capacitance, parasitic inductance, etc., while the second value mainly reflects the amount of unnecessary charge generated by parasitic capacitance, parasitic inductance, etc. Therefore, by taking the difference between the first value and the second value, the influence of the unnecessary charge amount is eliminated from the first value, and the difference mainly reflects the amount of charge accumulated in the component part. Therefore, by detecting the electrostatic capacitance of the component part based on the difference, the electrostatic capacitance that effectively suppresses the influence of parasitic capacitance, parasitic inductance, etc. can be obtained. Therefore, the detection accuracy of the load applied to the component part can be improved.

[0013] Furthermore, it is not necessary to configure a special circuit for detecting the electrostatic capacitance, and it is sufficient to switch the potentials applied to the two electrodes of the element portion as described above. Therefore, the electrostatic capacitance of the element portion can be detected with high accuracy using a simple configuration.

[0014] A second aspect of the present invention relates to a detection circuit for detecting the electrostatic capacitance from an element portion having a predetermined electrostatic capacitance. The detection circuit involved in this aspect comprises: a potential applying portion that applies a predetermined potential to two electrodes of the element portion; a measuring portion that measures the amount of electricity that changes due to charging or discharging of the electric charge on the element portion; and a control portion. The control portion performs the following processing: obtaining a first value based on the amount of electricity measured in a first mode in which different potentials are applied to the two electrodes; obtaining a second value based on the amount of electricity measured in a second mode in which the same potential is applied to the two electrodes; and detecting the electrostatic capacitance of the element portion based on the difference between the first value and the second value.

[0015] According to the detection circuit according to this aspect, the capacitance of the element portion can be detected with high accuracy, similarly to the above-mentioned first aspect.

[0016] Effects of the Invention

[0017] As described above, according to the present invention, it is possible to provide a load detection device and a detection circuit capable of detecting the electrostatic capacitance of a component portion with high accuracy.

[0018] The effects and significance of the present invention will be further clarified by the description of the following embodiments. However, the following embodiments are merely examples of implementing the present invention, and the present invention is not limited to the following embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 (a) is a perspective view schematically showing the base member according to Embodiment 1 and a conductive elastic body provided on the upper surface of the base member. Figure 1 (b) schematically shows the embodiment of the present invention. Figure 1 (a) is a perspective view of a structure in which a conductor line is provided.

[0020] Figure 2 (a) schematically shows the embodiment 1 involved in Figure 1 (b) is a three-dimensional diagram of a structure in a state where wires are provided. Figure 2 (b) schematically shows the embodiment 1 involved in Figure 2 (a) is a perspective view showing a state where a sheet-like member is provided in the structure.

[0021] Figure 3 (a) and Figure 3 (b) are views schematically showing cross sections of the load sensor according to Embodiment 1.

[0022] Figure 4 This is a plan view schematically showing the internal structure of the load sensor according to the first embodiment.

[0023] Figure 5 This is a block diagram showing the configuration of the load detection device according to the first embodiment.

[0024] Figure 6 : is a circuit diagram showing the structure of the potential applying section according to the first embodiment.

[0025] Figure 7 1 is a timing chart showing a gate signal output from a gate signal generating unit according to the first embodiment.

[0026] Figure 8 This is a diagram showing an operating state of a potential applying unit according to the first embodiment in a first mode of applying different potentials to two electrodes of a device unit to be measured.

[0027] Fig. 91 is a diagram showing an operating state of a voltage applying unit during discharge according to the first embodiment.

[0028] Fig.10 This is a diagram showing an operating state of the potential applying section according to the first embodiment in the second mode of applying the same potential to two electrodes of the element section to be measured.

[0029] Fig.11 1 is a diagram showing an operating state of a voltage applying unit during discharge according to the first embodiment.

[0030] Fig.12 1 is a timing chart schematically showing the current measured by the current measuring unit according to the first embodiment.

[0031] Fig.13 This is a diagram showing the operating state of the potential applying unit according to the first embodiment when the same potential is applied to two electrodes of the next element unit to be measured.

[0032] Fig.14 This is a flowchart showing the electrostatic capacitance detection process according to the first embodiment.

[0033] Fig.15 This is a graph showing simulation results of electrostatic capacitance according to the first embodiment.

[0034] Fig.16 1 is a flowchart showing the electrostatic capacitance detection process according to Modification Example 1.

[0035] Fig.17 1 is a diagram schematically showing an operating state of the potential applying section according to Modification Example 1 in the second mode of applying the same potential to two electrodes of the element section to be measured.

[0036] Fig.18 1 is a diagram schematically showing an operating state of the potential applying section according to Modification Example 1 in a first mode of applying different potentials to two electrodes of a device section to be measured.

[0037] Fig.19 : is a circuit diagram showing the structure of the potential applying section according to Modification Example 2.

[0038] Fig. 20 : is a circuit diagram showing the configuration of a load sensor and a potential applying unit according to Modification Example 3.

[0039] Fig.21 This is a block diagram showing the structure of a load detection device according to the second embodiment.

[0040] Fig. 22: is a circuit diagram showing the structure of a potential applying section according to the second embodiment.

[0041] Fig.23 This is a diagram showing an operating state of a potential applying section according to the second embodiment in a second mode in which the same potential is applied to two electrodes of a device section to be measured.

[0042] Fig.24 This is a diagram showing the operating state of the potential applying unit during discharge according to the second embodiment.

[0043] Fig.25 This is a diagram showing an operating state of a potential applying unit according to the second embodiment in a first mode of applying different potentials to two electrodes of a device unit to be measured.

[0044] Fig.26 This is a diagram schematically showing changes in voltage measured by a voltage measuring unit according to the second embodiment.

[0045] However, the drawings are mainly for illustration and do not limit the scope of the present invention. DETAILED DESCRIPTION

[0046] The load detection device according to the present invention can be applied to management systems that perform processing according to applied loads, etc. Examples of management systems include inventory management systems, driver monitoring systems, guidance management systems, safety management systems, and nursing / childcare management systems.

[0047] In an inventory management system, for example, a load sensor installed in an inventory shelf is used to detect the load of the loaded goods, thereby detecting the types and number of goods on the inventory shelf. In this way, goods can be efficiently managed in stores, factories, warehouses, etc., and staff can be streamlined. In addition, a load sensor installed in a refrigerator is used to detect the load of food in the refrigerator, thereby detecting the types, number, and quantity of food in the refrigerator. In this way, a menu using the food in the refrigerator can be automatically suggested.

[0048] In the driver monitoring system, for example, a load sensor provided on the steering device is used to monitor the load distribution of the driver on the steering device (e.g., gripping force, gripping position, pedaling force). In addition, a load sensor provided on the vehicle seat is used to monitor the load distribution of the driver on the vehicle seat when the driver is seated (e.g., center of gravity position). This can provide feedback on the driver's driving state (drowsiness, psychological state, etc.).

[0049] In the guidance management system, for example, load sensors provided on the soles of the shoes are used to monitor the load distribution on the soles of the feet, thereby correcting or guiding the foot to an appropriate walking state or walking state.

[0050] In the safety management system, for example, load sensors installed on the ground are used to detect the load distribution when a person passes by, and to detect weight, stride, speed, shoe sole pattern, etc. Thus, the person passing by can be identified by comparing the detection information with the data.

[0051] In the nursing / childcare management system, for example, load sensors installed on bedding and toilet seats are used to monitor the load distribution of the human body on the bedding and toilet seats, thereby estimating what actions the person is trying to take at the position of the bedding and toilet seats to prevent falling.

[0052] The load detection device of the following embodiment is applied to, for example, the management system described above. The load detection device of the following embodiment comprises: a load sensor for detecting a load; a detection circuit combined with the load sensor; and a control circuit for controlling the detection circuit. The load sensor of the following embodiment is an electrostatic capacitance type load sensor. Such a load sensor is sometimes also referred to as an "electrostatic capacitance type pressure sensitive sensor element", "capacitive pressure detection sensor element", "pressure sensitive switch element", etc. In addition, the following embodiment is one embodiment of the present invention, and the present invention is not limited by the following embodiment in any way.

[0053] The embodiments of the present invention are described below with reference to the accompanying drawings. For convenience, mutually orthogonal X, Y, and Z axes are shown in each drawing. The Z axis direction is the height direction of the load sensor 1.

[0054] <Implementation Method 1>

[0055] Reference Figure 1 (a)~ Figure 4 The load sensor 1 will be described.

[0056] Figure 1 (a) is a perspective view schematically showing the base member 11 and the conductive elastic body 12 provided on the upper surface (the surface on the positive side of the Z axis) of the base member 11 .

[0057] The base member 11 is a flat plate-shaped member having elasticity and insulating properties. The base member 11 has a rectangular shape when viewed from above. The thickness of the base member 11 is constant. The thickness of the base member 11 is, for example, 0.01 mm to 2 mm. When the thickness of the base member 11 is small, the base member 11 is sometimes referred to as a sheet member or a film member. The base member 11 is made of a non-conductive resin material or a non-conductive rubber material.

[0058] The resin material used for the base member 11 is, for example, at least one resin material selected from the group consisting of styrene resins, silicone resins (e.g., polydimethylpolysiloxane (PDMS)), acrylic resins, rotaxane resins, and polyurethane resins. The rubber material used for the base member 11 is, for example, at least one rubber material selected from the group consisting of silicone rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, polyisobutylene, ethylene-propylene rubber, chlorosulfonated polyethylene, acrylic rubber, fluororubber, epichlorohydrin rubber, polyurethane rubber, and natural rubber.

[0059] The conductive elastic body 12 is disposed on the upper surface (the surface on the positive side of the Z axis) of the base member 11. Figure 1 In (a), three conductive elastic bodies 12 are arranged on the upper surface of the base member 11. The conductive elastic body 12 is a member having elastic conductivity. Each conductive elastic body 12 has a strip shape that is long in the Y-axis direction. The three conductive elastic bodies 12 are arranged side by side at a predetermined interval in the X-axis direction. A wiring W2 electrically connected to the conductive elastic body 12 is provided at the end of each conductive elastic body 12 on the negative side of the Y-axis.

[0060] The conductive elastic body 12 is formed on the upper surface of the base member 11 by printing methods such as screen printing, gravure printing, flexographic printing, offset printing, and gravure offset printing. According to these printing methods, the conductive elastic body 12 can be formed on the upper surface of the base member 11 with a thickness of about 0.001 mm to 0.5 mm.

[0061] The conductive elastic body 12 is composed of a resin material and conductive fillers dispersed therein, or a rubber material and conductive fillers dispersed therein.

[0062] The resin material used for the conductive elastomer 12 is similar to the resin material used for the base member 11 described above, and is, for example, at least one resin material selected from the group consisting of styrene resins, silicone resins (polydimethylpolysiloxane (such as PDMS)), acrylic resins, rotaxane resins, and polyurethane resins.

[0063] The rubber material used for the conductive elastomer 12 is the same as the rubber material used for the base member 11 mentioned above, for example, at least one rubber material selected from the group consisting of silicone rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, polyisobutylene, ethylene-propylene rubber, chlorosulfonated polyethylene, propylene rubber, fluororubber, epichlorohydrin rubber, polyurethane rubber and natural rubber.

[0064] The conductive filler used for the conductive elastomer 12 is, for example, at least one material selected from the group consisting of metal materials such as Au (gold), Ag (silver), Cu (copper), C (carbon), ZnO (zinc oxide), In2O3 (indium (III) oxide) and SnO2 (tin (IV) oxide), conductive polymer materials such as PEDOT:PSS (i.e., a composite composed of poly (3,4-ethylenedioxythiophene) (PEDOT) and polystyrene sulfonic acid (PSS)), metal-coated organic fibers, metal wires (in fiber state) and other conductive fibers.

[0065] Figure 1 (b) schematically shows Figure 1 (a) is a perspective view of a structure in which a conductor wire 13 is provided.

[0066] The conductor wire 13 is a linear member and is arranged in a superimposed manner. Figure 1 (a) shows the upper surface of the conductive elastic body 12. In the present embodiment, three conductor lines 13 are arranged in a superimposed manner on the upper surfaces of the three conductive elastic bodies 12. The three conductor lines 13 are arranged side by side at predetermined intervals along the long side direction (Y-axis direction) of the conductive elastic body 12 in a manner that crosses the conductive elastic body 12. Each conductor line 13 is arranged to extend along the X-axis direction in a manner that spans the three conductive elastic bodies 12.

[0067] The conductor wire 13 is, for example, a copper wire with a coating. The conductor wire 13 is composed of a linear conductive member 13a and a dielectric 13b formed on the surface of the conductive member 13a. Figure 3 (a) and (b) are described below.

[0068] Figure 2 (a) schematically shows Figure 1 (b) is a perspective view of a structure in which a wire 14 is provided.

[0069] In such Figure 1 After the conductor wires 13 are arranged as in (b), each conductor wire 13 is connected to the base member 11 by the wire 14 so as to be movable along the longitudinal direction (X-axis direction) of the conductor wire 13. Figure 2 In the example shown in (a), twelve wires 14 connect the conductor wire 13 to the base member 11 at positions other than the position where the conductive elastic body 12 and the conductor wire 13 overlap. The wire 14 is made of chemical fiber, natural fiber, or a mixed fiber thereof.

[0070] Figure 2 (b) schematically shows Figure 2 (a) is a perspective view of a state where the base member 15 is provided in the structure.

[0071] from Figure 2 A base member 15 is provided above the structure shown in (a) (positive side of the Z axis). The base member 15 is an insulating member. The base member 15 is, for example, at least one resin material selected from a group consisting of polyethylene terephthalate, polycarbonate, and polyimide. The base member 15 may also be made of the same material as the base member 11. The base member 15 has a flat plate shape parallel to the XY plane, and has the same size and shape as the base member 11 when viewed from above. The thickness of the base member 15 in the Z-axis direction is, for example, 0.01 mm to 2 mm.

[0072] The outer circumference of the base member 15 is connected to the outer circumference of the base member 11 by using a silicone rubber adhesive, a wire, etc. Thus, the base member 15 is fixed to the base member 11. The conductor wire 13 is sandwiched between the conductive elastic body 12 and the base member 15. Figure 2 The load sensor 1 is completed as shown in (b). The load sensor 1 can be Figure 2 The state (b) is used in a state in which the positive and negative directions are reversed.

[0073] Figure 3 (a) and Figure 3 (b) is a diagram schematically showing a cross section of the load sensor 1 when the load sensor 1 is cut along a plane parallel to the YZ plane at the center position of the conductive elastic body 12 in the X-axis direction. Figure 3 (a) shows a state where no load is applied, Figure 3 (b) shows a state where a load is applied.

[0074] like Figure 3 As shown in (a) and (b), the conductor wire 13 is composed of a conductive member 13a and a dielectric 13b formed on the conductive member 13a. The conductive member 13a is a linear member having conductivity. The dielectric 13b covers the surface of the conductive member 13a. The conductive member 13a is composed of, for example, copper. The diameter of the conductive member 13a is, for example, about 60 μm.

[0075] The dielectric 13b has electrical insulation properties, and is made of, for example, a resin material, a ceramic material, a metal oxide material, etc. The dielectric 13b may be at least one resin material selected from the group consisting of polypropylene resin, polyester resin (e.g., polyethylene terephthalate resin), polyimide resin, polyphenylene sulfide resin, polyvinyl formal resin, polyurethane resin, polyamide-imide resin, polyamide resin, etc., or may be at least one metal oxide material selected from the group consisting of Al2O3 and Ta2O5, etc. The dielectric 13b is formed at least in the range of the portion of the conductor line 13 superimposed on the conductive elastic body 12.

[0076] like Figure 3As shown in (a), when no load is applied, the force applied between the conductive elastic body 12 and the conductor wire 13 and the force applied between the base member 15 and the conductor wire 13 are substantially zero. Figure 3 When a load is applied to the surface on the negative side of the Z axis of the base member 11 as shown in (b), the conductive elastic body 12 and the base member 11 are deformed by the conductor wire 13 .

[0077] like Figure 3 As shown in (b), due to the application of the load, the conductor wire 13 is wrapped by the conductive elastic body 12 and approaches the conductive elastic body 12. Along with this, the contact area between the conductor wire 13 and the conductive elastic body 12 increases. As a result, the electrostatic capacitance between the conductive member 13a and the conductive elastic body 12 changes. By detecting the electrostatic capacitance between the conductive member 13a and the conductive elastic body 12, the load applied to the area is obtained.

[0078] Figure 4 FIG. 1 is a top view schematically showing the internal structure of the load sensor 1. Figure 4 In the figure, for convenience, illustration of the wire 14 and the base member 15 is omitted.

[0079] like Figure 4 As shown, element portions A11, A12, A13, A21, A22, A23, A31, A32, and A33 whose electrostatic capacitance varies according to the load are formed at the positions where the three conductive elastic bodies 12 intersect the three conductor lines 13. Each element portion includes the conductive elastic body 12 and the conductor line 13 near the intersection of the conductive elastic body 12 and the conductor line 13.

[0080] In each element portion, the conductor line 13 constitutes one electrode (eg, anode) of the electrostatic capacitor, and the conductive elastic body 12 constitutes the other electrode (eg, cathode) of the electrostatic capacitor. Figure 3 (a), (b)) constitute one electrode of the load sensor 1 (capacitive load sensor), the conductive elastic body 12 constitutes the other electrode of the load sensor 1 (capacitive load sensor), and the dielectric 13b (refer to Figure 3 (a) and (b) of FIG. 1 correspond to the dielectric that defines the capacitance in the load sensor 1 (capacitive load sensor).

[0081] When a load is applied to each element portion in the Z-axis direction, the conductor wire 13 is wrapped in the conductive elastic body 12. As a result, the contact area between the conductor wire 13 and the conductive elastic body 12 changes, and the electrostatic capacitance between the conductor wire 13 and the conductive elastic body 12 changes. The end of the conductor wire 13 on the negative side of the X-axis and the end of the wiring W2 on the negative side of the Y-axis provided on the conductive elastic body 12 are aligned with the reference Figure 5It is connected to the detection circuit 2 described later.

[0082] If a load is applied to the element portion A11, the contact area of ​​the conductive member 13a of the conductor wire 13 and the conductive elastic body 12 via the dielectric 13b in the element portion A11 increases. In this case, the load applied to the element portion A11 can be calculated by detecting the electrostatic capacitance between the conductive elastic body 12 closest to the negative side of the X-axis and the conductor wire 13 closest to the positive side of the Y-axis. Similarly, in other element portions, the load applied to the other element portions can also be calculated by detecting the electrostatic capacitance between the conductive elastic body 12 and the conductor wire 13 intersecting in the other element portions.

[0083] Figure 5 It is a block diagram showing the structure of the load detection device 3.

[0084] The load detection device 3 includes the load sensor 1 and the detection circuit 2. The detection circuit 2 detects the electrostatic capacitance of each element of the load sensor 1. As described above, the electrostatic capacitance of each element changes according to the load applied to each element. The detection circuit 2 applies a predetermined potential to two electrodes of each element and detects the electrostatic capacitance of each element that changes according to the load.

[0085] The detection circuit 2 includes a potential applying section 100 , a current measuring section 200 , and a control section 300 .

[0086] The potential applying unit 100 applies a predetermined potential to two electrodes of each element unit. The potential applying unit 100 includes a potential generating unit 110, a first switching unit 120, and a second switching unit 130. The potential generating unit 110 generates a potential to be applied to two electrodes of each element unit. The first switching unit 120 selectively applies the potential generated by the potential generating unit 110 to the three conductor wires 13 of the load sensor 1. The first switching unit 120 selectively applies the potential generated by the potential generating unit 110 to the three conductive elastic bodies 12 of the load sensor 1.

[0087] The current measuring unit 200 measures a value corresponding to the amount of charge accumulated in the element unit by application of the potential. Here, as this value, the current measuring unit 200 measures the current flowing through the supply line L0 (see Figure 6 ) is the current flowing in the

[0088] The control unit 300 controls the potential applying unit 100 to apply a predetermined potential to the two electrodes of each element unit, obtains the measured value of the current measured by the current measuring unit 200 due to the application of the potential, and detects the electrostatic capacitance of each element unit based on the obtained measured value.

[0089] Specifically, the control unit 300 obtains a first value based on the current measured by the current measuring unit 200 in a first mode in which different potentials are applied to the two electrodes of the element unit as the measurement object, obtains a second value based on the current measured by the current measuring unit 200 in a second mode in which the same potential is applied to the two electrodes of the element unit as the measurement object, and detects the electrostatic capacitance of the element unit as the measurement object based on the difference between the first value and the second value. The electrostatic capacitance detection processing of the control unit 300 will be described later. Figures 8 to 14 Provide explanation.

[0090] Figure 6 is a circuit diagram showing the structure of the potential applying section 100 .

[0091] exist Figure 6 , for convenience, only the conductor wire 13 and the conductive elastic body 12 are shown as the structure of the load sensor 1, and the conductive elastic body 12 is shown as a line. For convenience, the current measuring unit 200 is included in the dotted line frame representing the potential generating unit 110 to indicate that the current flowing in the supply line L0 of the potential generating unit 110 is measured.

[0092] The potential generating section 110 includes a gate signal generating section 111 , switching elements 112 a and 112 b , and an equipotential generating section 113 .

[0093] The gate signal generating unit 111 generates a gate signal for turning on the switch elements 112a and 112b. The switch element 112a is composed of a P-type FET, and the switch element 112a is turned on by applying a low-level gate signal to the gate. The switch element 112b is composed of an N-type FET, and the switch element 112b is turned on by applying a high-level gate signal to the gate.

[0094] Figure 7 2 is a timing chart showing the gate signal output from the gate signal generating section 111 .

[0095] The upper gate signal G1 is a signal provided to the gate of the switching element 112a, and the lower gate signal G2 is a signal provided to the gate of the switching element 112b.

[0096] The gate signal G1 is at a low level (zero level) during period T1. Period T1 occurs within period T0. The gate signal G2 is at a high level during period T1. Period T2 occurs within period T0. The timing of occurrence of period T1 and period T2 are staggered. Therefore, when one of the switching elements 112a and 112b is in the conducting state, the other is in the non-conducting state. As described later, during period T1, the element portion is charged, and during period T2, the element portion is discharged.

[0097] Back to Figure 6The equipotential generating unit 113 is an operational amplifier, and generates a potential equal to the potential of the supply line L1 and applies the generated potential to the supply line L1.

[0098] The first switching unit 120 selectively connects one of the supply line L1 and the ground line L3 to the wiring W1 respectively extended from the plurality of conductor lines 13 (conductive members 13 a ).

[0099] Specifically, the first switching unit 120 includes three multiplexers 121 and one multiplexer 122. The supply line L1 is connected to the input terminal of the multiplexer 122. The multiplexer 122 has three output terminals. The three multiplexers 121 are connected to the three output terminals of the multiplexer 122, respectively. The three multiplexers 121 are provided corresponding to the three conductor wires 13 (conductive members 13a), respectively. The conductive member 13a (wiring W1) of the conductor wire 13 is connected to the output terminal of each multiplexer 121.

[0100] Each multiplexer 121 has two input terminals. One input terminal of the multiplexer 121 is connected to the multiplexer 122, and a power supply potential Vdd is applied to the input terminal via the supply line L1. The power supply potential Vdd is a potential generated by the power supply S1. The other input terminal of the multiplexer 121 is connected to the ground line L3.

[0101] The second switching unit 130 selectively connects one of the supply line L2 and the ground line L3 to the conductive elastic body 12 (wiring W2 ).

[0102] Specifically, the second switching unit 130 includes three multiplexers 131. The three multiplexers 131 are provided corresponding to the three conductive elastic bodies 12, respectively. The output side terminal of each multiplexer 131 is connected to the wiring W2 connected to the conductive elastic body 12. Each multiplexer 131 is provided with two input side terminals. A supply line L2 is connected to one input side terminal of the multiplexer 131. A ground line L3 is connected to the other input side terminal of the multiplexer 131.

[0103] The first switching unit 120 and the second switching unit 130 are composed of Figure 5 The control unit 300 controls the three conductor wires 13 (wiring W1) and the three conductive elastic bodies 12 (wiring W2). As a result, the power supply potential Vdd, the potential from the equipotential generating unit 113, or the ground potential is applied to the three conductor wires 13 (wiring W1) and the three conductive elastic bodies 12 (wiring W2).

[0104] The current measuring unit 200 measures the current flowing in the supply line L0. That is, when the switch element 112a is in the conducting state and the switch element 112b is in the non-conducting state ( Figure 7During a period T1 of 1, the current flowing in the supply line L0, that is, the current corresponding to the amount of charge transferred to the load sensor 1 via the supply lines L0, L1 and the first switching unit 120 is measured.

[0105] Next, refer to Figure 6 as well as Figure 8 to Figure 11 The detection operation of the electrostatic capacitance of each component part is described below. Figure 6 The element part A11 is set as the detection object of electrostatic capacitance. Figure 8 and Fig.10 In FIG. 1 , the thick solid line shows a path for applying a potential equal to the power supply potential Vdd to the load sensor 1, and the thick dotted line shows a path for applying a ground potential. Fig. 9 and Fig.11 In FIG. 1 , the thick solid line shows the path of the current flowing to the ground.

[0106] When the capacitance detection target is the element unit A11, the multiplexers 121 and 122 of the first switching unit 120 and the multiplexer 131 of the second switching unit 130 are set to Figure 6 In this state, if Figure 7 The gate signals G1 and G2 switch the switch element 112a to the on state. Figure 8 As shown in FIG. 1 , the power supply potential Vdd is applied to the conductor line 13 of the row including the element part A11 of the load sensor 1. Thus, the power supply potential Vdd is applied to one electrode (conductor line 13) of the three element parts A11 to A13 of the row. At this time, the other electrodes (three conductive elastic bodies 12) of the three element parts A11 to A13 are connected to the ground via the second switching part 130. Therefore, different potentials are applied to the two electrodes of the element parts A11 to A13. That is, in Figure 8 In the embodiment, the potential is applied based on the first mode.

[0107] By applying this potential, charges are accumulated in the three element portions A11 to A13, and a current Im flows through the supply line L0. The current Im flows through the supply line L0 until the accumulation of charges in the three element portions A11 to A13 is saturated. Figure 5 The control unit 300 calculates the current according to the measured value of the current measuring unit 200. Figure 7 The average current value of the current Im during the period T1.

[0108] Thus, when the period T1 ends, the switch element 112a becomes non-conductive, and the application of the power supply potential Vdd to the supply line L1 is cut off. Figure 7 When the period T2 arrives, the switch element 112b is turned on. Fig. 9As indicated by the dotted arrows, a current flows from the supply line L1 to the ground line L3, and the electric charges charged in the element portions A11, A12, and A13 are discharged toward the ground.

[0109] Thus, when the period T2 ends, the switch element 112b becomes non-conductive, and the connection between the supply line L1 and the ground line L3 is cut off. Figure 7 During the period T1 until the arrival of the period T2, the multiplexer 131 of the element unit A11 among the three multiplexers 131 of the second switching unit 130 is switched to the terminal side of the supply line L2. Figure 7 When the next period T1 arrives, the switch element 112a is turned on. Fig.10 As shown, a power supply potential Vdd is applied to the supply line L1.

[0110] In this case, the potential generated by the equipotential generating unit 113, that is, the potential equivalent to the power supply potential Vdd, is applied to the other electrode (conductive elastic body 12) of the element portion A11. Therefore, the same potential is applied to the two electrodes of the element portion A11. Figure 8 Similarly, different potentials (power supply potential Vdd and ground potential) are applied to the two electrodes of element parts A12 and A13. Fig.10 In the embodiment, the potential is applied based on the first mode.

[0111] By applying this potential, charges are accumulated in the three element portions A11 to A13, and the current Iref flows through the supply line L0. The current Iref flows through the supply line L0 until the accumulation of charges in the three element portions A11 to A13 is saturated. Figure 5 The control unit 300 calculates the current according to the measured value of the current measuring unit 200. Figure 7 The average current value of the current Iref during the period T1.

[0112] Thus, when the period T1 ends, the switch element 112a becomes non-conductive, and the application of the power supply potential Vdd to the supply line L1 is cut off. Figure 7 When the period T2 arrives, the switch element 112b is turned on. Fig.11 As shown by the dashed arrow, current flows from the supply line L1 to the ground line L3, and the charges charged in the element portions A11, A12, and A13 are discharged to the ground. Thus, the operation for detecting the electrostatic capacitance of the element portion A11 is completed.

[0113] Fig.12 2 is a timing chart schematically showing the current measured by the current measurement unit 200 through the above-mentioned operation.

[0114] exist Fig.12 The top level shows Figure 7 The gate signal G1. Fig.12 The second and third levels from the top show the case where the load applied to the element parts A11, A12, A13 is low and the case where the load applied to the element parts A11, A12, A13 is high. Figure 8 The current Im is measured by the action of Fig.12 The lowest level shows that when the load applied to the element parts A11, A12, and A13 is low, Figure 8 The current Iref is measured by the action.

[0115] like Fig.12 As shown in the second and third stages from the top, the greater the load applied to the element parts A11, A12, and A13, the higher the electrostatic capacitance, so the period until the current Im converges to zero (the period until the accumulation of charge is saturated) becomes longer. Therefore, the period T1 is set to be slightly longer than the period until the current Im converges to zero when the maximum load of the load detection range (dynamic range) is applied to the element parts A11, A12, and A13, that is, when the total electrostatic capacitance of the element parts A11, A12, and A13 is the maximum.

[0116] In addition, if Fig.12 As shown in the bottom level, due to the potential applied to the two electrodes of the element part A11 and Figure 8 The situation is different, so through Fig.10 The current Iref measured by the action is Fig.12 The current Im of the second stage from the top converges to zero earlier than that of the first stage.

[0117] Here, in Figure 8 The current Im measured in the first mode includes, in addition to the current component based on the charge accumulated in the element unit A11 serving as the measurement object, the current component based on the charge accumulated in other element units A12 and A13, and further includes the current component based on the charge accumulated in other element units other than the element units A12 and A13, the wiring between the supply line L0 and the load sensor 1, and the parasitic capacitance of each circuit unit.

[0118] Similarly, in Fig.10 The current Iref measured in the second mode includes, in addition to the current component based on the charge accumulated in the element unit A11 that is the measurement object, the current component based on the charge accumulated in other element units A12 and A13, and further includes the current component based on the charge accumulated in other element units other than the element units A12 and A13, the wiring between the supply line L0 and the load sensor 1, and the parasitic capacitance of each circuit unit.

[0119] Will Figure 8 and Fig.10 A comparison shows that the difference between the two methods of measuring currents Im and Iref lies only in the potential applied to the column of element portion A11. Fig.10 In the embodiment, the same potential is applied to the two electrodes of the element part A11, so almost no charge is accumulated in the element part A11. Fig.10 The current Iref measured by the action has almost no current component based on the charge accumulated in the element part A11 that is the measurement object, and is mainly superimposed with the current component based on the charge accumulated in other element parts A12 and A13, and the current component based on the charge accumulated in other element parts and parasitic capacitance.

[0120] Therefore, by subtracting the charge amount corresponding to the current Iref from the charge amount corresponding to the current Im, the charge amount accumulated in the above-mentioned elements other than the element portion A11 can be eliminated. That is, the difference between the charge amount corresponding to the current Im and the charge amount corresponding to the current Iref is substantially equivalent to the charge amount accumulated in the single element portion A11 when the power supply potential Vdd and the ground potential are applied to the two electrodes of the element portion A11.

[0121] Therefore, the capacitance C of the element portion A11 can be calculated by the following equation based on the average currents Im_av and Iref_av of the currents Im and Iref.

[0122] C=(Qm-Qref) / Vdd…(1)

[0123] Qm=Im_av·T1…(1-1)

[0124] Qref=Iref_av·T1…(1-2)

[0125] In formula (1), (Im_av-Iref_av)·T1 is the difference between the charge amount Qm of the current Im and the charge amount Qref of the current Iref. That is, the charge amount Qm is calculated according to formula (1-1), and the charge amount Qref is calculated according to formula (1-2). By calculating the electrostatic capacitance of the element part A11 according to formula (1), it is possible to obtain a high-precision electrostatic capacitance that suppresses the influence of parasitic capacitance, etc. as described above.

[0126] In addition, in this method, the parameter values ​​of formula (1), namely the average currents Im_av and Iref_av, are obtained from the stable state where the charge accumulation is completed and the currents Im and Iref converge to zero, and the charge amounts Qm and Qref of formulas (1-1) and (1-2) are obtained. Therefore, the electrostatic capacitance calculated according to formula (1) does not include the influence of parasitic inductance and parasitic impedance.

[0127] Even if a load is applied to the element portions A12 and A13 in the same row as the element portion A11, the charge accumulated in these element portions A12 and A13 is canceled by the above equation (1), so the electrostatic capacitance of the element portion A11 to be measured can be accurately calculated.

[0128] In addition, if Figure 8 and Fig.11 For comparison, Figure 8 and Fig.11 The difference is that the potential applied to the other electrode (conductive elastic body 12) of the other two element parts in the same column as the element part A11 to be measured. Fig.10 In the operation state, the power supply potential Vdd is not supplied to the two other element parts, but current is supplied to the two other element parts from the equipotential generating part 113. Therefore, even if Figure 8 and Fig.11 The voltage applied to the other electrode (conductive elastic body 12) of the two other element parts is different, and this difference does not affect the current flowing in the supply line L0. Therefore, the electrostatic capacitance of the element part A11 to be measured can be calculated with high accuracy according to the above formula (1).

[0129] So, when passing Figure 6 as well as Figure 8 to Figure 11 When the current Im and Iref required to calculate the electrostatic capacitance of the element part A11 are measured by the operation of the second switching part 130, the current Iref required to calculate the electrostatic capacitance of the next element part A12 is calculated. In this case, the multiplexer 131 in the middle of the second switching part 130 is switched from Figure 6 The state is switched to the terminal side of the supply line L2. In this state, when Figure 7 When the next period T1 arrives, if Fig.13 As shown, a potential equal to the power supply potential Vdd is applied to the other electrodes (conductive elastic body 12) of the element part A12, and the current Iref is measured. The control unit 300 calculates the average current Iref_av based on the measurement. The average current Iref_av and the average current Im_av are applied to the above formula (1) to calculate the electrostatic capacitance of the element part A12.

[0130] As for the component A13, the rightmost multiplexer 131 of the second switching unit 130 is switched similarly to the component A12, and the electrostatic capacitance is calculated by the above equation (1) based on the measurement result of the current Iref in the next period T1. As for the component parts of the middle row and the lowest row, the first switching unit 120 is switched to apply the power supply potential Vdd to these rows, and the same processing as above is performed to calculate the electrostatic capacitance of each component part. In this way, the electrostatic capacitance detection processing for all component parts is completed.

[0131] Fig.14 : is a flowchart showing the electrostatic capacitance detection process performed by the above-mentioned operation.

[0132] exist Fig.14 In the embodiment, step S101 corresponds to the potential measurement process in the first mode described above, and steps S102, S103, and S106 correspond to the potential measurement process in the second mode described above.

[0133] The control unit 300 applies different potentials to the two electrodes of each element unit of the row to be measured, and measures the current Im (S101). The operation of this step corresponds to Figure 8 In this step, the control unit 300 obtains the above-mentioned average current Im_av according to the measurement result of the current Im.

[0134] Next, the control unit 300 applies the same potential to the two electrodes of the element unit to be measured included in the row, and measures the current Iref (S102). The operation of this step corresponds to Fig.10 In this step, the control unit 300 obtains the above-mentioned average current Iref_av according to the measurement result of the current Iref.

[0135] The control unit 300 determines whether the current Iref has been measured for all the element units in the row (S103). If the answer in step S103 is "No", the control unit 300 switches the measurement object to the next element unit in the row and measures the current Iref (S102). The operation in this step corresponds to Fig.13 In this step, the control unit 300 obtains the above-mentioned average current Iref_av according to the measurement result of the current Iref.

[0136] Thus, the control unit 300 repeats the processing of steps S106 and S102 before measuring the current Iref for all the element units included in the row as the measurement object (S103: "No"). Thus, when the current Iref is measured for all the element units included in the row as the measurement object and the average current Iref_av of these element units is obtained (S103: "Yes"), the control unit 300 calculates the electrostatic capacitance of each element unit in the row based on the difference in the amount of charge based on the current Im and Iref (S104). Specifically, the control unit 300 applies the common average current Im_av obtained in step S101 and the average current Iref_av for each element unit obtained in step S102 to the above formula (1) for each element unit, thereby calculating the electrostatic capacitance of each element unit in the row as the measurement object.

[0137] In this way, when the detection of the electrostatic capacitance for the row is completed, the control unit 300 determines whether the detection of the electrostatic capacitance is completed for all the rows included in the load sensor 1 (S105). When the judgment of step S105 is "No", the control unit 300 switches the row to be measured to the next row (S107) and performs the processing after step S101. In this way, the electrostatic capacitance of each component part of the next row is detected. Before the control unit 300 performs the processing for all the rows (S105: "No"), it switches the rows to be measured in sequence (S107) and repeats the processing after step S101. In this way, when the electrostatic capacitance is detected for the component parts of all the rows (S105: "Yes"), the control unit 300 ends. Fig.14 processing.

[0138] In addition, Fig.14 In the flowchart, after the current Im is measured based on the first mode (step S101), the current Iref of each component part is measured based on the second mode (steps S102, S103, S106), but the current Im may be measured based on the first mode (step S101) after the current Iref of each component part is measured based on the second mode (steps S102, S103, S106).

[0139] In addition, Fig.14 Alternatively, step S104 may be moved between step S102 and step S103, and the electrostatic capacitance of the component part to be measured is calculated each time the current Iref is measured for the component part to be measured in step S102. Alternatively, the processing of step S104 may be moved to the post-stage of step S105, and the electrostatic capacitance of each component part is calculated after the processing for all rows is completed.

[0140] Fig.15 It is shown by Fig.14 A graph of simulation results of electrostatic capacitance detected by the electrostatic capacitance detection process.

[0141] In this simulation, the capacitance detected by the above-mentioned processing was obtained when the capacitance of a predetermined element portion was changed. Fig.15 In FIG. 1 , the horizontal axis is the electrostatic capacitance set for the target element portion, and the vertical axis is the electrostatic capacitance detected by the above-mentioned processing.

[0142] like Fig.15 As shown in FIG. 1 , the electrostatic capacitance detected by the above processing roughly matches the electrostatic capacitance set for the target component part, and a linear approximate straight line is obtained from the drawing of the simulation result. Therefore, it can be confirmed that according to the above processing, the electrostatic capacitance that effectively suppresses the influence of parasitic capacitance, parasitic inductance, etc. can be obtained for each component part.

[0143] <Effects of Implementation Method 1>

[0144] According to the above-described embodiment, the following effects can be achieved.

[0145] The charge amount Qm (first value) based on the current Im reflects the charge amount accumulated in the component part as the measurement object, and reflects the charge amount of unnecessary capacitance such as parasitic capacitance based on other component parts, wiring and circuit parts. The charge amount Qref (second value) based on the current Iref mainly reflects the charge amount of unnecessary capacitance such as parasitic capacitance based on other component parts, wiring and circuit parts. Therefore, by taking the difference between the charge amount Qm (first value) and the charge amount ref (second value), the influence of the charge amount based on unnecessary capacitance is eliminated from the current Im (first value), and the difference mainly reflects the charge amount accumulated in the component part as the measurement object. Therefore, by detecting the electrostatic capacitance of the component part as the measurement object based on the difference, it is possible to obtain an electrostatic capacitance that effectively suppresses the influence of the unnecessary charge amount. Therefore, it is possible to improve the detection accuracy of the load applied to the component part as the measurement object.

[0146] Furthermore, it is not necessary to configure a special circuit for detecting the electrostatic capacitance, and the potentials applied to the two electrodes of the element portion may be simply switched as described above. Therefore, the electrostatic capacitance of the element portion can be detected with high accuracy using a simple configuration.

[0147] like Figure 8 and Fig.10As shown, the current measuring unit 200 measures the current flowing in the charging path between an electrode (conductor wire 13) and the power supply S1 when a potential is applied as the amount of electricity that changes due to the charging of the charge on the component part. Thus, the current Im and Iref corresponding to the charge amount of the component part as the measurement object and the charge amount of other unnecessary capacitance can be measured. Therefore, the electrostatic capacitance of the component part as the measurement object can be appropriately obtained based on the difference between the charge amounts Qm and Qref based on these currents Im and Iref.

[0148] As reference Fig.12 As described, the control unit 300 obtains the charge amount Qm until charging is completed as the first value based on the current Im (average current Im_av) measured by the current measuring unit 200 in the first mode, and obtains the charge amount Qref until charging is completed as the second value based on the current Iref (average current Iref_av) measured by the current measuring unit 200 in the second mode, and calculates the electrostatic capacitance of the component part to be measured by the above formula (1) based on the charge amounts Qm, Qref and the potential difference V of different potentials. As a result, the electrostatic capacitance of the component part to be measured can be obtained with high accuracy as described above.

[0149] like Figure 6 As shown, the load sensor 1 has a plurality of element parts, the potential applying part 100 is configured to be able to switch the element part to which the potential is applied, the control part 300 controls the potential applying part 100 in the first mode and the second mode to apply the potential to each element part, obtains the current Im and the current Iref (electric quantity) for each element part from the current measuring part 200, and detects the electrostatic capacitance for each element part based on the charge quantity Qm (first value) and the charge quantity Qref (second value) based on the acquired current Im and current Iref (electric quantity) of each element part. According to this structure, since a plurality of element parts are arranged in the load sensor 1, the detection range of the load can be expanded. In addition, since the above-mentioned processing is performed for each element part, the electrostatic capacitance applied to each element part can be detected with high accuracy.

[0150] like Figure 6As shown, a plurality of element parts are arranged in a matrix in a manner of arranging a plurality of rows and columns, one of the two electrodes of the element parts in the same row is connected to each other, and the other of the two electrodes of the element parts in the same column is connected to each other, and the potential applying part 100 is provided with multiplexers 121, 122, 131 (switching elements) for switching the rows and columns to which the potential is to be applied. According to this structure, since a plurality of element parts are arranged in a matrix, the distribution of the load extending in a square range can be detected by these element parts. In addition, by switching the rows and columns to which the potential is to be applied using the multiplexers 121, 122, 131 (switching elements), a predetermined potential can be applied to the two electrodes of the element part located at the intersection of the switched rows and columns, respectively, and the electrostatic capacitance of the element part can be smoothly detected by the above-mentioned control.

[0151] like Fig.14 As shown, the control unit 300 applies different potentials to both ends of all the element units included in the row as the measurement object at the same time in the first mode, and obtains the charge amount Qm (first value) shared by these element units (S101), and in the second mode, sequentially switches the element units of the multiple element units included in the row as the measurement object, which are the measurement objects that apply the same potential to two electrodes (S106), and obtains the charge amount Qref (second value) for each element unit as the measurement object (S102, S103), and detects the electrostatic capacitance of each element unit according to the difference between the shared charge amount Qm (first value) and the charge amount Qref (second value) of each element unit (S104). According to this process, the charge amount Qm (first value) is obtained for the element units of a row at the same time, so that the electrostatic capacitance detection process can be performed on each element unit simply and quickly.

[0152] <Change Example 1>

[0153] In the above embodiment 1, if Fig.14 As shown, in the first mode, different potentials are applied to the two electrodes of all the element parts included in the row as the measurement object at the same time, and after the current Im shared by these element parts is measured (S101), in the second mode, the element parts as the measurement object in the plurality of element parts included in the row as the measurement object, which have the same potential applied to the two electrodes, are switched in sequence, and the current Iref is measured for each element part as the measurement object (S102, S103, S106).

[0154] In contrast, in variation 1, in the second mode, the same potential is simultaneously applied to the two electrodes of all element portions included in the row as the measurement object, and after measuring the current Iref shared by these element portions, in the first mode, the element portions as the measurement object in which different potentials are applied to the two electrodes among the multiple element portions included in the row as the measurement object are switched in sequence, and the current Im is measured for each element portion as the measurement object.

[0155] Fig.16 1 is a flowchart showing the electrostatic capacitance detection process according to Modification Example 1.

[0156] exist Fig.16 In the embodiment, step S111 corresponds to the potential measurement process in the second mode described above, and steps S112, S113, and S116 correspond to the potential measurement process in the first mode described above.

[0157] The control unit 300 Fig.12 During the period T1 of , the same potential (power supply potential Vdd) is simultaneously applied to the two electrodes of all the element parts included in the row as the measurement object, and the current Iref shared by these element parts is measured (S111). That is, in step S111, the control unit 300 sets the first switching unit 120 and the second switching unit 130 to simultaneously apply the same potential (power supply potential Vdd) to both ends of all the element parts in the row as the measurement object, and then Fig.12 During the period T1, the same potential (power supply potential Vdd) is applied to the two electrodes of the element part to be measured. The control unit 300 calculates the average current Iref_av during the period T1 based on the current Iref measured by the current measurement unit 200 during the period T1, and obtains the charge amount Qref based on the calculated Iref_av.

[0158] Next, the control unit 300 sequentially switches the element units as the measurement target units included in the row as the measurement target units, which apply different potentials to the two electrodes, and measures the current Im for each element unit as the measurement target unit (S112, S113, S116). That is, in step S112, the control unit 300 sets the first switching unit 120 and the second switching unit 130 to apply different potentials (power supply potential Vdd, ground potential) to the two electrodes of the element unit as the measurement target, and Fig.12 In the next period T1, different potentials (power supply potential Vdd, ground potential) are applied to the two electrodes of the element unit to be measured. The control unit 300 calculates the average current Im_av in the period T1 based on the current Im measured by the current measurement unit 200 in the period T1.

[0159] In step S116, the control unit 300 switches the measurement target to the next element unit in the row as the measurement target. In step S112, the control unit 300 obtains the current Im from the current measurement unit 200 in the next period T1 and calculates the average current Im_av for the element unit. The control unit 300 performs this process on all element units in the row as the measurement target in sequence (S113).

[0160] In this way, when the processing for all the element parts of the row to be measured is completed (S113: "Yes"), the control unit 300 calculates the electrostatic capacitance of each element part of the row based on the difference between the charge amount Qm based on the current Im and the charge amount Qref based on the current Iref (S114). Specifically, the control unit 300 applies the common average current Iref_av obtained in step S111 and the average current Im_av for each element part obtained in step S112 to the above-mentioned equations (1), (1-1), and (1-2) for each element part to calculate the electrostatic capacitance of each element part of the row to be measured.

[0161] In this way, when the detection of the electrostatic capacitance for the row is completed, the control unit 300 determines whether the detection of the electrostatic capacitance for all the rows included in the load sensor 1 is completed (S115). When the judgment of step S115 is "No", the control unit 300 switches the row to be measured to the next row (S117) and performs the processing after step S111. In this way, the electrostatic capacitance of each component part of the next row is detected. Before the control unit 300 performs the processing for all the rows (S115: "No"), it switches the rows to be measured in sequence (S117) and repeats the processing after step S111. In this way, when the electrostatic capacitance is detected for the component parts of all the rows (S115: "Yes"), the control unit 300 ends. Fig.16 processing.

[0162] Fig.17 is a schematic diagram showing the execution of Fig.16 FIG. 4 is a diagram showing a state of application of a potential to each element portion of a row to be measured in the case of step S111 (second mode).

[0163] Here, the row to be measured is set as the top row, and the element unit to be measured is set as the element unit A11. The power supply potential Vdd is applied to one electrode of the three element units included in the top row, and the potential from the equipotential generating unit 113 is applied to the other electrode. During the period T1 in which this state is formed, the control unit 300 calculates the average current Iref_av based on the current Iref measured by the current measuring unit 200.

[0164] Fig.18is a schematic diagram showing the execution of Fig.16 FIG. 4 is a diagram showing a state of application of a potential to each element portion of a row to be measured in the case of step S112 (first mode).

[0165] As in the first embodiment described above, Fig.17 The second mode and Fig.18 Between the first mode, Figure 7 The discharge operation is performed during the period T2. The setting states of the first switching unit 120 and the second switching unit 130 during the discharge operation are the same as Fig.17 The setting status is the same.

[0166] like Fig.18 As shown, among the three element units in the uppermost row, only the element unit A1 to be measured has two electrodes to which different potentials are applied. During the period T2 in which this state is formed, the control unit 300 calculates the average current Im_av for the element unit A1 from the current Im measured by the current measurement unit 200.

[0167] The control unit 300 performs the same discharge operation as described above in the next period T2. Thereafter, the control unit 300 sets the second switching unit 130 to apply the ground potential to the electrode (conductive elastic body 12) of the center column before the next period T1. In this way, the control unit 300 calculates the average current Im_av for the element unit A12 in the next period T1. The control unit 300 calculates the average current Im_av of the element unit A13 by the same process.

[0168] thus, Fig.16 The judgment of step S113 is "yes". In step S114, the control unit 300 calculates the electrostatic capacitance of the component parts A11, A12, and A13 respectively according to the common average current Iref_av and the average current Im_av obtained for the component parts A11, A12, and A13 by the above-mentioned equations (1), (1-1), and (1-2). The control unit 300 performs the same processing on other rows. In this way, the electrostatic capacitance is calculated for all the component parts.

[0169] According to Modification 1, it is also possible to achieve the same effects as those of Embodiment 1 described above.

[0170] In addition, if Fig.16As shown, in the second mode, the control unit 300 simultaneously applies the same potential to both ends of all the element units included in the row as the measurement object, and obtains the charge amount Qref (second value) shared by these element units (S111). In the first mode, the element units of the multiple element units included in the row as the measurement object, which are the measurement objects that apply different potentials to the two electrodes, are switched in sequence (S116), and the charge amount Qm (first value) is obtained for each element unit as the measurement object (S112, S113), and the electrostatic capacitance of each element unit is detected according to the difference between the charge amount Qm (first value) of each element unit and the shared charge amount Qref (second value) (S114). According to this process, the charge amount Qref (second value) is obtained for the element units of a row at the same time, so that the electrostatic capacitance detection process of each element unit can be simply and quickly performed.

[0171] In addition, Fig.16 In the flowchart, after the current Iref is measured based on the second mode (step S111), the current Im of each component part is measured based on the first mode (steps S112, S113, S116), but it is also possible to measure the current Im based on the second mode (step S111) after the current Im of each component part is measured based on the first mode (steps S112, S113, S116).

[0172] In addition, Fig.16 Alternatively, step S114 may be moved between step S112 and step S113, and the electrostatic capacitance of the component part to be measured is calculated each time the current Im is measured for the component part to be measured in step S112. Alternatively, the processing of step S114 may be moved to the post-stage of step S115, and the electrostatic capacitance is calculated for each component part after the processing for all rows is completed.

[0173] <Change Example 2>

[0174] In the first embodiment, the current flowing in the charging path between one electrode (conductor wire 13) and the power source S1 is measured as the electric quantity that changes due to the charging of the electric charge to the element portion. In contrast, in the second modification, the current flowing in the discharge path between one electrode (conductor wire 13) and the ground line L3 is measured as the electric quantity that changes due to the discharge of the electric charge to the element portion.

[0175] Fig.19 : is a circuit diagram showing the structure of the potential applying section 100 according to the second modification.

[0176] like Fig.19As shown in FIG. 1 , in the second modification, a current measuring unit 200 is arranged between the switching element 112 b and the ground line L3. Fig.19 When the discharge is shown, Figure 7 The current (current Im, Iref) flowing from the switching element 112b to the ground line L3 is measured during the period T2. The control unit 300 calculates the average current (average current Im_av, Iref_av) during the period T2 based on the measured current, and calculates the electrostatic capacitance C of each element part according to the following formula (2). Formula (2) is the same as the above formula (1). Formulas (2-1) and (2-2) are obtained by changing T1 of the above formulas (1-1) and (1-2) to T2.

[0177] C=(Qm-Qref) / Vdd…(2)

[0178] Qm=Im_av·T2…(2-1)

[0179] Qref=Iref_av·T2…(2-2)

[0180] The detection process of the electrostatic capacitance of each element is similar to that of the present invention except that the current (current Im, Iref) is measured during the discharge operation (period T2). Fig.14 The detection process is the same. That is, in step S101 (first mode), different potentials are applied during period T1, and current Im is measured during period T2 that appears after period T1. In addition, in step S102 (second mode), the same potential is applied during period T1 that appears after period T2, and current Iref is measured during period T2 that appears after period T1.

[0181] As in the first embodiment, the order of the first mode (step S101) and the second mode (steps S102, S103, S106) may be reversed. In addition, the detection process of the electrostatic capacitance of each element portion may be the same as that of the first modification. Fig.16 In this case, in the second mode (step S111), the element parts of the row to be measured are charged by applying a potential during the period T1, and the current Iref is measured when the discharge is performed in the next period T2. In addition, in the first mode (steps S112, S113, S116), the element parts of the row to be measured are charged by applying a potential during the next period T1, and the current Im is measured when the discharge is performed in the next period T2. In addition, in this case, the order of the second mode (step S111) and the first mode (steps S112, S113, S116) may be reversed.

[0182] Also in the second modification, the same effects as those of the first embodiment described above are achieved.

[0183] That is, Fig.19 As shown, the current measuring unit 200 measures the current flowing in the discharge path between an electrode (conductor line 13) and the ground line L3 when a potential is applied as the amount of electricity that changes due to the discharge of the charge to the element part. Thus, the current Im and Iref corresponding to the charge amount of the element part as the measurement object and the charge amount of other unnecessary capacitance can be measured. Therefore, the electrostatic capacitance of the element part as the measurement object can be appropriately obtained based on the difference between the charge amount Qm based on the current Im and the charge amount Qref based on the current Iref.

[0184] In addition, the control unit 300 obtains the charge amount Qm (first value) until the discharge is completed based on the current Im measured by the current measurement unit 200 in the first mode, and obtains the charge amount Qref (second value) until the discharge is completed based on the current Iref measured by the current measurement unit 200 in the second mode, and calculates the electrostatic capacitance of the component part to be measured by the above equations (2), (2-1), and (2-2) based on the charge amounts Qm, Qref, and the potential difference V between different potentials. In this way, the electrostatic capacitance of the component part to be measured can be obtained with high accuracy.

[0185] <Change Example 3>

[0186] In the first embodiment described above, the plurality of element portions are arranged in a matrix, but the number and arrangement of the element portions are not limited thereto.

[0187] Fig. 20 : is a circuit diagram showing the configuration of the load sensor 1 and the potential applying unit 100 according to the third modification.

[0188] In the third modification, the load sensor 1 includes only three element portions A11 to A13 . The three element portions A11 to A13 are arranged in a row. That is, the load sensor 1 includes one conductor wire 13 and three conductive elastic bodies 12 .

[0189] In this structure, there are no second and third row element parts in the load sensor 1, so there is no need for, for example, Fig.10 As in the case of , current is supplied from the equipotential generating section 113 to the other two element sections in the same column as the element section A11. Fig. 20 As shown, the equipotential generating section 113 is omitted, and the power supply potential Vdd of the supply line L1 can be directly applied to each element portion A11 via the supply line L2.

[0190] In addition, Fig. 20In the structure of FIG. 1 , a multiplexer 112 is used as a structure for selectively connecting the supply line L1 to the supply line L0 and the ground line L3. The multiplexer 112 is switched according to the control from the control unit 300. The multiplexer 112 is connected to the supply line L0 side during the period T1, and is connected to the ground line L3 side during the period T2.

[0191] In addition, in the above-mentioned embodiment 1, it is also possible to Fig. 20 Similarly, the multiplexer 112 is used instead of the switch elements 112a and 112b. The element for selectively connecting the supply line L1 to the supply line L1 and the ground line L3 is not limited to the switch elements 112a and 112b and the multiplexer 112, and may be another switch such as a mechanical switch.

[0192] In the configuration of Modification 3, Fig.14 Steps S105 and S107 are omitted. Fig.16 Steps S115 and S117. In this case, it may also be, Fig.14 The processing of step S101 (first mode) and the processing of steps S102, S103, and S106 (second mode) are in the opposite order. Fig.16 The processing of step S111 (second mode) and the processing of steps S112, S113, and S116 (first mode) are in the opposite order.

[0193] In addition, in the structure of Modification Example 3, Fig.19 In the second modification shown, the current measuring unit 200 is disposed between the multiplexer 112 and the ground line L3 to measure the current during discharge. In this case, the capacitance of each element is calculated by the above equation (2) as in the second modification.

[0194] In addition, you can also Fig. 20 In the structure, the components A12 and A13 are further omitted, and the second switching unit 130 has only the multiplexer 131 corresponding to the component A11. In this case, the currents Im and Iref are measured for the component A11, and the electrostatic capacitance of the component A11 is calculated by the above formula (1) or formula (2).

[0195] <Implementation Method 2>

[0196] In the first embodiment, the current flowing in the path between one electrode (conductor line 13) of the element part and the power source S1 is measured as the electric quantity that changes due to the charge or discharge of the electric charge performed on the element part. In contrast, in the second embodiment, the voltage of the element part is measured as the electric quantity that changes due to the charge or discharge of the electric charge performed on the element part.

[0197] Fig.21 This is a block diagram showing the configuration of the load detection device 3 according to the second embodiment.

[0198] like Fig.21 As shown, in Modification Example 3, instead of Figure 5 The current measuring unit 200 is replaced by the voltage measuring unit 400 for measuring the voltage of the element unit in the detection circuit 2 .

[0199] Fig. 22 : is a circuit diagram showing the structure of the potential applying section 100 according to the second embodiment.

[0200] exist Fig. 22 In FIG. 1 , for convenience, the voltage measuring section 400 is included in a dotted frame representing the potential generating section 110 to indicate that the voltage between the supply line L0 and the ground line L3 (the voltage of the element section) is measured.

[0201] exist Fig. 22 In the structure of Figure 6 In the structure of , the gate signal generating unit 111, the switching elements 112a and 112b, and the current measuring unit 200 are omitted, and the switch 114, the resistor 115, the switch 116, the resistor 117, and the voltage measuring unit 400 are added.

[0202] The switch 114 selectively connects the supply line L0 of the power supply potential Vdd to the resistor 115. The switch 116 and the resistor 117 constitute a discharge path for discharging the charge accumulated in the element portion. During discharge, the switch 116 is closed. As a result, the charge accumulated in the element portion is discharged to the ground line L3. The voltage measuring unit 400 measures the voltage between the supply line L0 and the ground line L3 (the voltage of the element portion). The voltage measuring unit 400 may also be an A / D converter that converts the potential of the output terminal 118 into a digital signal and outputs it to the control unit 300.

[0203] Fig.23 1 is a diagram showing the operating state of the potential applying unit 100 in the second mode in which the same potential is applied to two electrodes of the element unit A11 to be measured. Fig.23 In FIG. 1 , a thick solid line indicates a path to which a potential equivalent to the power supply potential Vdd is applied.

[0204] After the discharge operation for the load sensor 1 is performed, the control unit 300 closes the switch 114 for a certain period of time, thereby applying the power supply potential Vdd to the circuit unit on the downstream side of the switch 114. As a result, the power supply potential Vdd is applied to one electrode (conductor line 13) of the three element units A11 to A13, and the same potential as the power supply potential Vdd is applied to the other electrode (conductive elastic body 12) from the equipotential generating unit 113. The control unit 300 obtains the voltage Vref measured by the voltage measuring unit 400 at a predetermined timing after the switch 114 is closed.

[0205] Fig.24 It is shown by Fig.23 The diagram shows the operation state of the potential applying unit 100 when the charged charge is discharged by the operation of the potential applying unit 100. Fig.24 In FIG. 1 , the thick solid line shows the discharge path of the charge.

[0206] The control unit 300 closes the switch 116 for a certain period of time after opening the switch 114. This discharges the charges accumulated in the element units A11 to A13.

[0207] Fig.25 1 is a diagram showing the operating state of the potential applying unit 100 in the first mode in which different potentials are applied to two electrodes of the element unit A11 to be measured. Fig.25 In FIG. 1 , a thick solid line indicates a path to which a potential equivalent to the power supply potential Vdd is applied, and a thick dotted line indicates a path to which a ground potential is applied.

[0208] exist Fig.24 After the discharge, the control unit 300 opens the switch 116, switches the connection destination of the leftmost multiplexer 131 of the second switching unit 130 to the terminal on the ground line L3 side, and closes the switch 114. As a result, in the element unit A11, one electrode (conductor line 13) is applied with the power supply potential Vdd, and the other electrode (conductive elastic body 12) is applied with the ground potential. In the element units A12 and A13, one electrode (conductor line 13) is applied with the power supply potential Vdd, and the same potential as the power supply potential Vdd is applied to the other electrode (conductive elastic body 12) from the equipotential generating unit 113. The control unit 300 obtains the voltage Vm measured by the voltage measuring unit 400 at a predetermined timing after the switch 114 is closed. Thereafter, the control unit 300 opens the switch 114 and closes the switch 116, thereby discharging the load sensor 1.

[0209] Fig.26 is schematically shown in Fig.23 and Fig.25 4 is a diagram showing changes in voltage measured by the voltage measuring unit 400 during the operation of .

[0210] like Fig.26 As shown in FIG. 1 , when different potentials are applied to the element portion to be measured, the time until convergence to the power supply potential Vdd becomes longer than when the same potential is applied. Therefore, after the potential is applied, the voltage Vm is smaller than the voltage Vref among the voltages Vm and Vref measured by the voltage measuring unit 400 at a timing after a certain time ΔT.

[0211] The control unit 300 calculates the capacitance C of the element unit to be measured by the following equation (3) based on the difference ΔV between the voltage Vm and the voltage Vref. R in the equation (3) is the resistance value of the resistor 115 .

[0212] [Number 1]

[0213]

[0214] Through Fig.14 or Fig.16 The same process is performed to detect the electrostatic capacitance of each element portion. Fig.14 and Fig.16 The measurement of the current Im and Iref in the process is replaced by the measurement of the voltage Vm and Vref. In addition, the electrostatic capacitance in steps S104 and 114 is calculated by the above formula (3). As in the case of the above-mentioned embodiment 1 and the modification 1, the order of obtaining the voltage Vm and the voltage Vref can be any one of them. In addition, as in the above-mentioned modification 2, the voltage Vm and Vref can also be obtained during the discharge operation. In this case, R in the formula (3) is the resistance value of the resistor 117.

[0215] (Effects of Embodiment 2)

[0216] In Embodiment 2, the voltage Vm is a voltage that includes the influence of the amount of charge of the component part as the measurement object and the influence of the amount of unnecessary charge accumulated in the component parts and parasitic capacitance other than the measurement object, and the voltage Vref is a voltage that mainly includes the influence of the amount of unnecessary charge accumulated in the component parts and parasitic capacitance other than the measurement object. Therefore, by using the above formula (3) and calculating the electrostatic capacitance of the component part as the measurement object based on the time change of the difference ΔV between the voltages Vm and Vref, it is possible to suppress the influence of the amount of unnecessary charge accumulated in the component parts and parasitic capacitance other than the measurement object on the detection result of the electrostatic capacitance. Therefore, compared with the case where the electrostatic capacitance is calculated using only the voltage Vm, the accuracy of the calculation result of the electrostatic capacitance can be improved.

[0217] However, in implementation mode 2, if Fig.26As shown in the figure, the voltages Vm and Vref are acquired before the charge accumulation is saturated, that is, when the current and voltage are changing, so the acquired voltages Vm and Vref may include the influence of parasitic inductance and parasitic impedance. Therefore, compared with the above-mentioned embodiment 1, the electrostatic capacitance calculated based on these voltages Vm and Vref may include error components. Therefore, in order to obtain the electrostatic capacitance with higher accuracy, it is preferable to use the current Im and Iref corresponding to the charge amount in the state where the charge accumulation in the element part is saturated, as in the above-mentioned embodiment 1, to obtain the electrostatic capacitance to be measured.

[0218] <Other Changes>

[0219] In the above-mentioned first and second embodiments, the multiplexer 122 is arranged in the first switching section 120 at the front stage of the three multiplexers 112, but the multiplexer 122 may be omitted and the supply line L1 may be directly connected to one input terminal of the three multiplexers 112. Thus, the influence of the parasitic capacitance and the like generated by the multiplexer 122 can be suppressed. However, in this case, when the currents Im and Iref are obtained, the power supply potential Vdd is applied to all the three multiplexers 121. Therefore, the influence of the parasitic capacitance and the like of the multiplexer 121 connected to the rows other than the row to be measured can be expected. The first switching section 120 is preferably configured so that the equivalent capacitance viewed from the supply line L1 is as small as possible.

[0220] In the first embodiment, the current measuring unit 200 measures the current flowing in the supply line L0, but the current flowing in another position on the path between one electrode (conductor line 13) of the element unit and the power source S1 may be measured. Fig.19 In the second modification example, the current measuring unit 200 may be arranged to detect the current at another position on the path between one electrode (conductor wire 13) and the ground line L3 during discharge.

[0221] In addition, in the above-mentioned embodiment 1, the average current Im_av and Iref_av are multiplied by the period T1 to calculate the charge amount Qm and Qref, but the method for obtaining the charge amount Qm and Qref is not limited to this. For example, when the average current Im_av and Iref_av are calculated for the period T0, the charge amount Qm and Qref can also be calculated by multiplying the average current Im_av and Iref_av by the period T0. In addition, instead of multiplying by the period T0, the charge amount Qm and Qref can be calculated by dividing the average current Im_av and Iref_av by the frequency F0 of the period T0. Alternatively, the current Im and Iref can be accumulated during the period T1 to obtain the charge amount Qm and Qref.

[0222] Furthermore, in the above-mentioned first and second embodiments, the first switching section 120 and the second switching section 130 are constituted by the multiplexers 121, 122, and 131, but the first switching section 120 and the second switching section 130 may be constituted by a switching circuit other than a multiplexer.

[0223] In the above-mentioned first and second embodiments, the conductor wire 13 is composed of a copper wire with a coating layer, but it is not limited to this, and may be composed of a linear conductive member containing a material other than copper and a dielectric coating the conductive member. In addition, the conductive member may be composed of a stranded metal wire.

[0224] In addition, in the above-mentioned embodiments 1 and 2, the conductive elastic body 12 is provided only on the surface on the positive side of the Z axis of the base member 11, but the conductive elastic body may also be provided on the surface on the negative side of the Z axis of the base member 15. In this case, the conductive elastic body on the side of the base member 15 is configured in the same manner as the conductive elastic body 12 on the side of the base member 11, and is configured to overlap with the conductive elastic body 12 with the conductor line 13 sandwiched therebetween when viewed from above. Moreover, the cable led out from the conductive elastic body on the side of the base member 15 is connected to the cable 12a led out from the conductive elastic body 12 facing each other in the Z axis direction. In this way, when the conductive elastic body is provided up and down with respect to the conductor line 13, the change in the electrostatic capacitance of the element portion is approximately twice that corresponding to the upper and lower conductive elastic bodies, so that the detection sensitivity of the load applied to the element portion can be improved.

[0225] In the above-mentioned first and second embodiments, the dielectric 13b is formed on the conductive member 13a so as to cover the outer periphery of the conductive member 13a, but the dielectric 13b may be formed on the upper surface of the conductive elastic body 12 instead. In this case, the conductive member 13a sinks in a manner of being wrapped inside the conductive elastic body 12 and the dielectric 13b in accordance with the application of the load, and the contact area between the conductive member 13a and the conductive elastic body 12 changes. Thus, the load applied to the element portion can be detected in the same manner as in the above-mentioned embodiment.

[0226] In the above-mentioned embodiments 1 and 2, the element portion is formed by the conductive elastic body 12 and the conductor wire 13 intersecting each other, but the structure of the element portion is not limited to this. For example, the element portion may be formed by a structure in which a dielectric is sandwiched between a hemispherical conductive elastic body and a flat electrode. In this case, the dielectric may be formed on the surface of the electrode facing the conductive elastic body, or may be formed on the surface of the hemispherical conductive elastic body.

[0227] In addition, the detection circuit involved in the present invention can be appropriately used not only to detect electrostatic capacitance from a load sensor, but also to detect electrostatic capacitance from an element part having a specified electrostatic capacitance, such as a capacitor element, an electrolytic capacitor, a ceramic capacitor, etc. formed in an electrostatic touch panel or a semiconductor device.

[0228] In addition, the embodiments of the present invention can be variously modified as appropriate within the scope of the technical concept shown in the claims.

[0229] (Note)

[0230] According to the description of the above embodiments, the following technology is disclosed.

[0231] (Technology 1)

[0232] A load detection device, characterized by comprising:

[0233] a load sensor including an element portion whose electrostatic capacitance changes according to a load; and

[0234] a detection circuit that detects the electrostatic capacitance of the element portion,

[0235] Wherein, the detection circuit has:

[0236] a potential applying unit that applies a predetermined potential to the two electrodes of the element unit;

[0237] a measuring unit that measures an amount of electricity that changes due to charging or discharging of electric charge with respect to the element unit; and

[0238] Control Department,

[0239] The control unit performs the following processing:

[0240] Acquire a first value according to the electrical quantity measured in a first mode in which different potentials are applied to the two electrodes;

[0241] acquiring a second value according to the electrical quantity measured in a second mode in which the same potential is applied to the two electrodes; and

[0242] The electrostatic capacitance of the element portion is detected based on the difference between the first value and the second value.

[0243] According to this technology, the difference between the first value and the second value is the value obtained by eliminating the influence of parasitic capacitance, parasitic inductance, etc. from the first value, and mainly reflects the amount of charge accumulated in the component part. Therefore, by detecting the electrostatic capacitance of the component part based on the difference, it is possible to obtain an electrostatic capacitance that effectively suppresses the influence of parasitic capacitance, parasitic inductance, etc. Therefore, the detection accuracy of the load applied to the component part can be improved. In addition, there is no need to configure a special circuit for detecting the electrostatic capacitance, as long as the potential applied to the two electrodes of the component part is switched as described above. Therefore, the electrostatic capacitance of the component part can be detected with high accuracy through a simple structure.

[0244] (Technique 2)

[0245] The load detection device according to technology 1 is characterized in that:

[0246] The measuring section measures a current flowing in a charging path of the potential applying section as the electric quantity.

[0247] According to this technology, the current corresponding to the charge amount of the element part and the charge amount of other unnecessary capacitance can be measured in the first mode and the second mode. Therefore, the electrostatic capacitance of the element part to be measured can be appropriately acquired based on the difference between these currents.

[0248] (Technique 3)

[0249] The load detection device according to technology 1 is characterized in that:

[0250] The measuring section measures a current flowing in a discharge path of the potential applying section as the electrical quantity.

[0251] According to this technique, the current corresponding to the charge amount of the element part and the charge amount of other unnecessary capacitance can be measured in the first mode and the second mode as in Technique 2. Therefore, the electrostatic capacitance of the element part to be measured can be appropriately acquired based on the difference between these currents.

[0252] (Technique 4)

[0253] The load detection device according to technology 2 or 3 is characterized in that:

[0254] The control unit performs the following processing:

[0255] acquiring, as the first value, an amount of charge Qm until the charging or the discharging is completed based on the current Im measured by the measuring unit in the first mode;

[0256] acquiring, as the second value, the amount of charge Qref until the charging or the discharging is completed based on the current Iref measured by the measuring section in the second mode; and

[0257] The electrostatic capacitance of the element portion is calculated from the charge amounts Qm, Qre and the potential difference V between the different potentials by the following relational expression:

[0258] Wherein, C = (Qm-Qref) / V.

[0259] According to this technology, the electrostatic capacitance of the element portion to be measured can be acquired with high accuracy using the above-mentioned formula.

[0260] (Technique 5)

[0261] The load detection device according to technology 1 is characterized in that:

[0262] The measuring unit measures a voltage of the element unit as the electrical quantity.

[0263] According to this technique, the voltage corresponding to the charge amount of the element part and the charge amount of other unnecessary capacitance can be measured in the first mode and the second mode. Therefore, the electrostatic capacitance of the element part to be measured can be appropriately acquired based on the difference between these voltages.

[0264] (Technique 6)

[0265] The load detection device according to technology 5 is characterized in that:

[0266] The control unit detects the electrostatic capacitance of the element unit based on a temporal change in a difference ΔV between the voltage Vm measured by the measurement unit in the first mode and the voltage Vref measured by the measurement unit in the second mode.

[0267] According to this technology, the electrostatic capacitance of the element portion to be measured can be acquired with high accuracy.

[0268] (Technique 7)

[0269] The load detection device according to any one of techniques 1 to 6 is characterized in that:

[0270] The load sensor includes a plurality of the element parts.

[0271] The potential applying section is configured to be able to switch the element section to which the potential is applied,

[0272] The control unit controls the potential applying unit to apply the potential to each of the component units in the first mode and the second mode, obtains the electric charge from the measuring unit for each of the component units, and detects the electrostatic capacitance for each of the component units based on the first value and the second value of the electric charge obtained for each of the component units.

[0273] According to this technology, since a plurality of element portions are arranged, the load detection range can be expanded. In addition, since the above-mentioned processing is performed on each element portion, the electrostatic capacitance applied to each element portion can be detected with high accuracy.

[0274] (Technology 8)

[0275] The load detection device according to technology 7 is characterized in that:

[0276] The plurality of element portions are arranged in a matrix in a plurality of rows and columns.

[0277] One of the two electrodes of the element parts in the same row is connected to each other,

[0278] The other of the two electrodes of the element parts in the same column are connected to each other,

[0279] The potential applying section includes a switching element that switches between the row and the column to which the potential is to be applied.

[0280] According to this technology, since a plurality of element parts are arranged in a matrix, the distribution of loads extending into a square range can be detected by these element parts. In addition, by switching the row and column to which the potential is to be applied using a switching element, a predetermined potential can be applied to the two electrodes of the element part located at the intersection of the row and column after switching, respectively, and the electrostatic capacitance of the element part can be smoothly detected by the above control.

[0281] (Technique 9)

[0282] The load detection device according to technology 8 is characterized in that:

[0283] The control unit performs the following processing:

[0284] In the first mode, different potentials are simultaneously applied to two electrodes of all the element portions included in the row to be measured, and the first value common to these element portions is acquired;

[0285] In the second mode, the element units as the measurement target for applying the same potential to the two electrodes among the plurality of element units included in the row as the measurement target are sequentially switched, and the second value is acquired for each of the element units as the measurement target; and

[0286] The electrostatic capacitance of each of the element portions is detected based on the difference between the common first value and the second value of each of the element portions.

[0287] According to this technique, since the first value is acquired collectively for the element portions in one row, it is possible to simply and quickly perform the electrostatic capacitance detection process for each element portion.

[0288] (Technology 10)

[0289] The load detection device according to technology 8 is characterized in that:

[0290] The control unit performs the following processing:

[0291] In the second mode, the same potential is simultaneously applied to the two electrodes of all the element portions included in the row as the measurement object, and the second value common to these element portions is obtained;

[0292] In the first mode, the element units as the measurement target for applying different potentials to the two electrodes among the plurality of element units included in the row as the measurement target are sequentially switched, and the first value is acquired for each of the element units as the measurement target; and

[0293] The electrostatic capacitance of each of the element portions is detected based on the difference between the first value of each of the element portions and the common second value.

[0294] According to this technique, since the second value is acquired collectively for the element portions in one row, it is possible to simply and quickly perform the electrostatic capacitance detection process for each element portion.

[0295] (Technology 11)

[0296] A detection circuit detects an electrostatic capacitance from a component portion having a predetermined electrostatic capacitance, the detection circuit comprising:

[0297] a potential applying unit that applies a predetermined potential to the two electrodes of the element unit;

[0298] a measuring unit configured to measure an amount of electricity changed by charging or discharging electric charge to the element unit; and

[0299] Control Department,

[0300] The control unit performs the following processing:

[0301] Acquire a first value according to the electrical quantity measured in a first mode in which different potentials are applied to the two electrodes;

[0302] acquiring a second value according to the electrical quantity measured in a second mode in which the same potential is applied to the two electrodes; and

[0303] The electrostatic capacitance of the element portion is detected based on the difference between the first value and the second value.

[0304] According to this technique, the same effect as that of technique 1 can be achieved.

[0305] Description of Reference Numerals

[0306] 1: load sensor; 2: detection circuit; 3: load detection device; 100: potential applying section; 200: current measuring section (measuring section); 300: control section; 400: voltage measuring section (measuring section); A11 to A16: element section.

Claims

1. A load detection device, characterized in that: have: a load sensor including an element portion whose electrostatic capacitance changes according to a load; and a detection circuit that detects the electrostatic capacitance of the element portion, Wherein, the detection circuit has: a potential applying unit that applies a predetermined potential to the two electrodes of the element unit; a measuring unit that measures an amount of electricity that changes due to charging or discharging of electric charge with respect to the element unit; and Control Department, The control unit performs the following processing: Acquire a first value according to the electrical quantity measured in a first mode in which different potentials are applied to the two electrodes; acquiring a second value according to the electrical quantity measured in a second mode in which the same potential is applied to the two electrodes; and The electrostatic capacitance of the element portion is detected based on the difference between the first value and the second value.

2. The load detection device according to claim 1, characterized in that: The measuring section measures a current flowing in a charging path of the potential applying section as the electric quantity.

3. The load detection device according to claim 1, characterized in that: The measuring section measures a current flowing in a discharge path of the potential applying section as the electrical quantity.

4. The load detection device according to claim 2 or 3, characterized in that: The control unit performs the following processing: acquiring, as the first value, an amount of charge Qm until the charging or the discharging is completed based on the current Im measured by the measuring unit in the first mode; acquiring, as the second value, an amount of charge Qref until the charging or the discharging is completed based on the current Iref measured by the measuring unit in the second mode; as well as The electrostatic capacitance of the element portion is calculated from the charge amounts Qm, Qre and the potential difference V between the different potentials by the following relational expression: Wherein, C = (Qm-Qref) / V.

5. The load detection device according to claim 1, characterized in that: The measuring unit measures a voltage of the element unit as the electrical quantity.

6. The load detection device according to claim 5, characterized in that: The control unit detects the electrostatic capacitance of the element unit based on a temporal change in a difference ΔV between the voltage Vm measured by the measurement unit in the first mode and the voltage Vref measured by the measurement unit in the second mode.

7. The load detection device according to claim 1, characterized in that: The load sensor includes a plurality of the element parts. The potential applying section is configured to be able to switch the element section to which the potential is applied, The control unit controls the potential applying unit to apply the potential to each of the component units in the first mode and the second mode, obtains the electric charge from the measuring unit for each of the component units, and detects the electrostatic capacitance for each of the component units based on the first value and the second value of the electric charge obtained for each of the component units.

8. The load detection device according to claim 7, characterized in that: The plurality of element portions are arranged in a matrix in a plurality of rows and columns. One of the two electrodes of the element parts in the same row is connected to each other, The other of the two electrodes of the element parts in the same column are connected to each other, The potential applying section includes a switching element that switches the row and the column to which the potential is to be applied.

9. The load detection device according to claim 8, characterized in that: The control unit performs the following processing: In the first mode, different potentials are simultaneously applied to two electrodes of all the element portions included in the row to be measured, and the first value common to these element portions is acquired; In the second mode, the element units as the measurement target for applying the same potential to the two electrodes among the plurality of element units included in the row as the measurement target are sequentially switched, and the second value is acquired for each of the element units as the measurement target; and The electrostatic capacitance of each of the element portions is detected based on the difference between the common first value and the second value of each of the element portions.

10. The load detection device according to claim 8, characterized in that: The control unit performs the following processing: In the second mode, the same potential is simultaneously applied to the two electrodes of all the element portions included in the row as the measurement object, and the second value common to these element portions is obtained; In the first mode, the element units as the measurement target for applying different potentials to the two electrodes among the plurality of element units included in the row as the measurement target are sequentially switched, and the first value is acquired for each of the element units as the measurement target; and The electrostatic capacitance of each of the element portions is detected based on the difference between the first value of each of the element portions and the common second value.

11. A detection circuit for detecting a predetermined electrostatic capacitance from a component portion having the predetermined electrostatic capacitance, the detection circuit comprising: a potential applying unit that applies a predetermined potential to the two electrodes of the element unit; a measuring unit configured to measure an amount of electricity changed by charging or discharging electric charge to the element unit; and Control Department, in, The control unit performs the following processing: Acquire a first value according to the electrical quantity measured in a first mode in which different potentials are applied to the two electrodes; acquiring a second value according to the electrical quantity measured in a second mode in which the same potential is applied to the two electrodes; as well as The electrostatic capacitance of the element portion is detected based on the difference between the first value and the second value.

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