JPH0755615A - Capacitance type force sensor - Google Patents

Abstract

PURPOSE:To provide a capacitance type force sensor capable of enhancing electrostatic capacity, and downsizing a pressure detecting part. CONSTITUTION:An elastic dielectric 14 and electrodes 13, 15 are plurally laminated to form a capacitor element 4, and the capacitor element 4 and a coil element 6 are arranged in a pressure detecting part 1. The capacitor element 4 is electrically connected to the coil element 6 in parallel to each other, and forms a resonance circuit for determining a resonance frequency f0 together with a circuit provided on the outside of the pressure detecting part 1. When a pressure F is added to the capacitor element 4, the opposed distance (t) of the capacitor element 4 is changed to change an electrostatic capacity C, and this change is determined from the change of the resonance frequency to measure the pressure F. Since the electrostatic capacity C of the capacitor element 4 is the electrostatic capacity of the elastic dielectric, it can be detected as a large value, and the pressure detecting part can be structurally downsized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitance type force sensor for measuring pressure by changing the capacitance of a capacitor element.

[0002]

2. Description of the Related Art In recent years, the use environment of force sensors has become harsh, the range of measurement has expanded, and the measurement range has ranged from high vacuum to high pressure. In response, there is a demand for smaller products.

By the way, as a force sensor for measuring such a pressure, for example, a fixed electrode and a moving electrode supported by a spring or the like which is displaced according to the amount of pressurization are provided, and the capacitance between these electrodes is measured. An electrostatic capacity type force sensor that obtains the amount of pressurization by doing so is used.

[0004]

However, in the conventional capacitance type force sensor as described above, since the capacitance to be measured is air, the relative dielectric constant is as small as 1 and an extremely low capacitance is measured. Therefore, it is difficult to install the amplifier circuit and eliminate the influence of stray capacitance such as lead wires.

Further, in view of the structure, if the distance between the electrodes is made small or the area of the counter electrode is made large in order to make the electrostatic capacitance a large value, the fixing and design of the moving electrode becomes complicated, and the pressure detecting portion of the force sensor is complicated. However, there is a problem in that the size is increased and the cost is increased.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electrostatic capacitance type force sensor capable of increasing the electrostatic capacitance and downsizing the pressure detecting portion.

[0007]

In order to achieve the above-mentioned object, a first electrostatic capacity type force sensor according to the present invention is designed to obtain a pressure change by obtaining a change in an electrostatic capacity according to a pressing force of a capacitor element of a pressure detecting section. In the electrostatic capacitance type force sensor for measuring, an elastic dielectric material that elastically changes by pressure is interposed between the opposing electrodes of the capacitor element.

Further, in order to achieve the above object, the second capacitance type force sensor according to the present invention is a static pressure sensor for measuring pressure by obtaining a change in capacitance due to the applied pressure of the capacitor element of the pressure detecting portion. A capacitance type force sensor in which an elastic dielectric whose dielectric constant increases with temperature rise and an elastic dielectric whose dielectric constant decreases with temperature rise are interposed between opposed electrodes of the capacitor element. Is.

Further, in order to achieve the above object, the third electrostatic capacity type force sensor according to the present invention is a static pressure sensor for measuring a pressure by obtaining a change in electrostatic capacity according to a pressing force of a capacitor element of a pressure detecting section. In the capacitance type force sensor, between the opposing electrodes of the capacitor element, a plurality of layers are laminated with an elastic dielectric that elastically changes by being interposed, and the number of layers of one electrode and the number of layers of the other electrode are And the above capacitor element is formed differently.

Further, in order to achieve the above object, a fourth electrostatic capacity type force sensor according to the present invention is a static capacitance sensor for measuring pressure by obtaining a change in electrostatic capacity associated with a pressing force of a capacitor element of a pressure detecting section. In the capacitance type force sensor, an elastic dielectric material that elastically changes by pressurization and a buffer amplification layer that adjusts a change in electrostatic capacitance due to a pressure are interposed between the opposing electrodes of the capacitor element.

Further, in order to achieve the above object, the fifth electrostatic capacity type force sensor according to the present invention is a static capacitance sensor for measuring a pressure by obtaining a change in electrostatic capacity according to a pressing force of a capacitor element of a pressure detecting section. In the capacitance type force sensor, a plurality of elastic dielectrics that elastically change by pressure are interposed between the opposing electrodes of the capacitor element, and the opposing electrodes extend in the direction of the terminals on each side. Each of the bonding electrode surfaces that is exposed and is lapped and bonded to each of the terminals is formed so that the area becomes smaller as it is stacked from the terminals to the outside.

[0012]

[Operation] To measure the pressure with the first capacitive force sensor having the above-mentioned configuration, when the pressure is applied to the capacitor element of the pressure detection unit, this pressure causes an intervening electrode between the opposing electrodes of the capacitor element. The mounted elastic dielectric material changes elastically, and the distance between the opposing electrodes changes. Therefore, the capacitance of the capacitor element changes, and the pressure is obtained by obtaining the change in capacitance.

Further, in the second capacitance type force sensor having the above structure, when pressure is applied to the capacitor element of the pressure detecting portion, this pressure force causes a temperature difference between the opposing electrodes of the capacitor element. The elastic dielectric whose dielectric constant increases with increasing temperature and the elastic dielectric whose dielectric constant decreases with increasing temperature elastically change, and the distance between the opposing electrodes changes. Therefore, the capacitance of the capacitor element changes, and the pressure is obtained by obtaining the change in capacitance.

Further, in the third capacitance type force sensor having the above-mentioned structure, when pressure is applied to the capacitor element of the pressure detecting portion, this pressing force causes elastic change due to pressurization laminated between a plurality of opposing electrodes. The elastic dielectric material that undergoes the elastic change changes the distance between the opposing electrodes provided with different numbers of laminated layers. Therefore, the capacitance of the capacitor element changes, and the pressure is obtained by obtaining the change in capacitance.

Further, in the fourth capacitance type force sensor having the above structure, when pressure is applied to the capacitor element of the pressure detecting portion, the applied pressure is interposed between the opposing electrodes of the capacitor element. The elastic dielectric material that elastically changes by pressurization and the buffer amplification layer that adjusts the change of the electrostatic capacitance with the applied pressure elastically change, and the distance between the opposing electrodes changes. Therefore, the capacitance of the capacitor element changes, and the pressure is obtained by obtaining the change in capacitance.

Further, in the fifth capacitance type force sensor having the above structure, when pressure is applied to the capacitor element of the pressure detecting portion, this pressing force extends in the direction of each terminal on each side and causes each of the terminals to be connected. A plurality of layers that are elastically changed by pressure between the opposing electrodes of the capacitor element, formed so that the surface of each of the bonding electrodes to be lap-bonded to each other is overlapped from the terminals to the outside The elastic dielectric material changes its elasticity and the distance between the opposing electrodes changes. Therefore, the capacitance of the capacitor element changes, and the pressure is obtained by obtaining the change in capacitance.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 show a first embodiment of the present invention, and FIG. 1 is an explanatory view of the structure of a capacitor element of a capacitance type force sensor,
2 is a schematic explanatory diagram of the circuit configuration of the capacitance type force sensor, FIG. 3 is an explanatory diagram showing the configuration of the pressure detection part of the capacitance type force sensor, and FIG. 4 is a diagram showing the electrode portion of the capacitor element and the lead wire. FIG. 5 is an explanatory view showing the connection method, and FIG. 5 is an explanatory view showing the connection between the electrode portion of the capacitor element and the lead wire.

In these drawings, reference numeral 1 indicates a pressure detecting portion of the capacitance type force sensor, and the pressure detecting portion 1 is mounted on an insulating fixing plate 3 provided in a detecting portion holder 2 and has a predetermined static pressure. A capacitor element 4 having an electric capacity C is provided, and the pressure-receiving surface side of the capacitor element 4 (the surface side opposite to the insulating fixing plate 3) seals the inside of the detection unit holder 2 and the object to be measured. A pressure receiving plate 5 for receiving the pressure is provided.

Further, the detector holder 2 of the pressure detector 1
Inside, a coil element 6 which is electrically connected in parallel with the capacitor element 4 and has a predetermined inductance L is arranged.

Further, as shown in FIG. 2, one electrode side of the capacitor element 4 and the coil element 6 connected in parallel is pulled out from the inside of the detection portion holder 2 of the pressure detection portion 1. The capacitor element 4 and the coil element 6 that are electrically grounded and that are connected in parallel are also provided.
The other electrode side of the impedance element 8 is connected to the input side of the amplifier 7 (impedance Zi) and the impedance element connected to the output side of the amplifier 7. 9 (impedance Z0) to form a resonance circuit.

Here, Rr represents an internal resistance, and if the internal resistance Rr is much smaller than the impedance Zi and the impedance Z0, the oscillation frequency of the circuit becomes the resonance frequency f0.

The output side of the amplifier 7 is connected to a counter circuit 10 that counts the resonance frequency f0. The counter circuit 10 processes data, calculates numerical values, controls measurement system, and the like. It is connected to the main controller 11.

The main controller 11 obtains the electrostatic capacitance C based on the well-known equation for the resonance frequency f0, f0 = 1 / {2π (LC) ^1/2 } (1) Further, the dielectric constant ε or the facing distance t is obtained from the electrostatic capacitance C based on the following equation. Here, the facing area is S,
When the number of layers is N, C = ε × (S / t) × N (2) Then, the facing distance t is obtained from the equation (2), and the amount of pressurization (pressure) obtained in advance is calculated. The pressure amount (pressure F) is obtained from the relationship (relational expression or map) between F) and the facing distance t.

On the other hand, as shown in FIG. 1, the capacitor element 4 includes an electrode 13, an elastic dielectric material 14, and the electrode 1 described above.
A plurality of counter electrodes 15 corresponding to 3 are alternately laminated and formed, and the electrodes 13 and the counter electrodes 15 are formed.
An electrode protection layer 16 is formed on the outer side of.

The elastic dielectric material 14 is made of an amorphous polymer material having elasticity and good restoring property, such as an amorphous polymer material containing silicon. In this embodiment, It is formed in three layers. In addition, the electrode 1
3, 15 are joined to the lead wire terminals 17, 18, respectively.

In the first embodiment, the elastic dielectric material 14 is formed in three layers, but the elastic dielectric material 14 is not limited to three layers and may be formed in two layers or four or more layers. By thus forming the elastic dielectric body 14 in a plurality of laminated structures, it is possible to obtain a capacitance of a predetermined size.

The electrode protection layer 16 may be made of the same material as the elastic dielectric material 14 or a different material.

Next, a method of joining the electrodes 13 and 15 of the capacitor element 4 and the lead wires 17 and 18 will be described with reference to FIGS. First, in the capacitor body 4a in which the electrodes 13, the elastic dielectrics 14, and the counter electrode 15 are alternately laminated in a plurality, the electrodes 13 and 15 are drawn out to the outside of the respective electrodes as bonding electrode surfaces. Be done. (FIG. 4A shows a state in which the electrode 15 is pulled out from the capacitor body 4a.)
Next, the joined electrode surfaces from which the electrodes 13 and 15 have been extracted are sequentially processed from the lower side to the upper side so as to have a small trapezoidal shape (FIG. 4B).

Then, the electrodes 13 and 15 are brought into contact with the terminal lead wires 17 and 18, respectively, and wound and soldered (the portion 19 in FIG. 5). Here, the electrode 1
Since 3 and 15 are sequentially processed into a small trapezoidal shape from the lower side to the upper side, soldering can be performed easily and reliably.

Next, the procedure for measuring the pressure F using the capacitance type force sensor having the above-mentioned structure will be described.
First, when the pressure detector 1 is located at a place where the pressure F can be measured and the pressure F is applied to the internal capacitor element 4 via the pressure receiving plate 5, the elastic dielectric body 1 of the capacitor element 4 is
In No. 4, the thickness is smaller than that under no load, the electrodes 13 and 15 facing each other approach each other, and the lead wires 17 and 18 respectively.
The capacitance C between them becomes large.

The change in the capacitance C appears as a change in the resonance frequency f0 of the resonance circuit. The change in the resonance frequency f0 is obtained by counting by the counter circuit 10, and the main controller 11 obtains the electrostatic capacitance C by processing the data, calculating the numerical value, etc. based on the equation (1). Also,
From the value of the capacitance C obtained above, the facing distance t is obtained based on the above-mentioned equation (2), and the pressure is calculated from the relationship (relational expression or map) between the pressure F and the facing distance t which is obtained in advance. Find F.

As described above, according to the first embodiment, the pressure is measured by using the capacitor element having the elastic dielectric, and the pressure detecting section includes the coil element and the capacitor element which form the resonance circuit. Since it is only installed, harsh use environment, for example, during underground boring,
It is possible to measure gas discharge pressure, water pressure, etc. several kilometers away with high accuracy. That is, only the coil element and the capacitor element that form the resonance circuit are arranged in the pressure detection unit, and by forming the elastic dielectric of the capacitor element with, for example, an amorphous polymer material, The pressure can be measured even in a high temperature atmosphere of 200 ° C.

Further, since only the coil element and the capacitor element forming the resonance circuit are arranged in the pressure detecting section, the pressure detecting section can be further miniaturized and various elements can be obtained. It becomes possible to perform the measurement.

Further, if the pressure detecting portion and the other circuit portion are connected to each other in a non-contact manner by using, for example, a rotary transformer, it is possible to measure a rotating object.

In the first embodiment, the elastic dielectric body 14 is described as having three layers, but the number of layers is not limited to three and may be two or four or more. By forming the elastic dielectric body 14 into a plurality of laminated structures, it is possible to obtain a capacitance of a predetermined size.

Further, the resonance circuit constructed in the first embodiment is not limited to the one in the first embodiment, but other resonance circuits (for example, a circuit to which CL series resonance is applied) are constructed. It may be possible to measure with the use of a capacitor element, and a circuit other than the resonance circuit may be configured as long as the capacitance of the capacitor element can be measured.

Further, the capacitor element and the coil element of the first embodiment are arranged and used in the detecting portion holder. The shape of the detecting portion holder is the same as that of the first embodiment. The capacitor element is not limited to the above, and only the capacitor element may be packaged with a resin material or the like. If the capacitor element is configured in this way, the pressure detection unit of the force sensor can be further downsized, and various pressure measurements can be performed.

Although both electrodes of the capacitor element are joined to the lead wire by soldering, they may be joined by welding, melting, adhesion (adhesion with a conductive adhesive or the like), or the like. Alternatively, it may be directly bonded to the element substrate.

Next, FIG. 6 is an explanatory view showing a capacitor element of a capacitance type force sensor according to a second embodiment of the present invention. In the second embodiment, when the elastic dielectric material has a capacitance change rate having a positive characteristic with respect to temperature (the capacitance change rate increases as the temperature rises), What has a negative characteristic with respect to temperature (capacitance change rate decreases with increasing temperature) is alternately laminated, and the capacitance change rate with respect to temperature is averaged. However, the other same structural parts are denoted by the same reference numerals as those in the first embodiment, and description thereof will be omitted.

That is, in FIG. 6, reference numeral 21 indicates a capacitor element in the pressure detecting portion 1, and the dielectric constant between the electrode 13 and the counter electrode 15 increases with temperature rise (of the positive characteristic). ) An elastic dielectric body 22 and an elastic dielectric body 23 whose dielectric constant increases (negative characteristic) with temperature rise are alternately formed.

A material such as polyethylene terephthalate may be used as the positive dielectric elastic dielectric material 22, and a material such as polypropylene may be used as the negative dielectric elastic dielectric material 23.

As described above, by using elastic dielectrics having different characteristics with respect to temperature in combination, the rate of change in capacitance with respect to temperature can be averaged, and temperature drift can be suppressed, without temperature correction. Accurate pressure measurement can be performed. The rest of the configuration, functions and effects are the same as those of the first embodiment, so description thereof will be omitted.

Next, FIG. 7 is an explanatory view showing a capacitor element of a capacitance type force sensor according to a third embodiment of the present invention. The third embodiment is different in that a buffer amplification layer is further added to the laminated structure of the electrode of the capacitor element and the elastic dielectric provided in the pressure detecting portion of the first embodiment, and the other same. The structural parts are given the same reference numerals as in the first embodiment described above, and their explanations are omitted.

That is, in FIG. 7, reference numeral 31 indicates a capacitor element in the pressure detecting section 1, and the electrodes 13 of three layers are shown.
And 4 layers of elastic dielectric 14 and 3 for the electrode 13
A plurality of layers of counter electrodes 15 are alternately laminated,
A buffer amplification layer 32 of one layer is laminated in the middle portion. Further, in the figure, an electrode protective layer 16 is formed outside the electrodes 13 and 15.

As the material of the buffer amplification layer 32, which is likely to be thinned by pressurization and has a good restoring property when the pressurization is released, for example, a closed cell of silicon rubber or the like is used.

As described above, by providing the buffer amplification layer 32, it is possible to buffer or amplify the change of the electrostatic capacitance C with respect to the applied pressure F and detect the electrostatic capacitance C.
It is possible to increase the degree of freedom in setting. Further, even if a large pressure is suddenly applied, it can be absorbed by the buffer amplification layer.

In the third embodiment, one buffer amplification layer is laminated at the center. However, the laminated position is not limited to the center, and the upper side (pressurizing surface side) or the lower side may be laminated. Alternatively, two or more buffer amplification layers may be alternately stacked. The rest of the configuration, functions and effects are the same as those of the first embodiment, so description thereof will be omitted.

Next, FIG. 8 shows a capacitor element of a capacitance type force sensor according to a fourth embodiment of the present invention, (a) is an explanatory view of the structure of the capacitor element, and (b) is an elasticity of the capacitor element. Electrode wrapped in dielectric (electrode layer with elastic dielectric)
FIG.

In the fourth embodiment, in the capacitor element formed by laminating the electrode, the elastic dielectric and the buffer amplification layer described in the third embodiment, the electrode is previously covered with the elastic dielectric. It is formed by forming an electrode layer with an elastic dielectric and then laminating it with a buffer amplification layer.

That is, as shown in FIG. 8, the electrode layer 42 with elastic dielectric of the capacitor element 41 has a portion 42a on the side to be extracted and processed, and a portion 42 on the side to be laminated.
b is previously formed by being coated with the elastic dielectric 43.

Then, the processed side portions 42a of the electrode layer 42 with elastic dielectric are alternately inverted 180 degrees, and the buffer amplification layer 32 is provided between the electrode layers 42 with elastic dielectric.
Are laminated to form the capacitor element 41.

By using such a capacitor element 41, in addition to the effect of the third embodiment, the x1 and x2 dimensions in FIG. 8A are formed to be the same, and the elastic dielectric having the same thickness dimension is formed. As a body, it is possible to uniformly output changes in capacitance with respect to pressure. It is also possible to intentionally form the x1 and x2 dimensions differently so that only a predetermined range of pressure is emphasized and a change in capacitance is output.

Further, since the electrodes are preliminarily formed with the elastic dielectric material and are separately manufactured as the electrode layer with the elastic dielectric material, it is possible to reduce the number of steps when the capacitor elements are laminated and formed. The rest of the configuration, functions and effects are the same as those of the third embodiment, and therefore will be omitted. Next, FIG. 9 shows a capacitor element of a capacitance type force sensor according to a fifth embodiment of the present invention.
(A) is explanatory drawing of the structure of a capacitor element, (b) is explanatory drawing of arrangement | positioning of an electrode.

In the fifth embodiment, the laminated structure of the electrodes of the capacitor element and the elastic dielectric material provided in the pressure detecting portion of the first embodiment has an odd number of electrodes on one side, and the electrodes are opposed to each other. The electrode has an even number of electrodes and is laminated to enhance the shield effect. Other structural parts that are the same as those in the first embodiment are designated by the same reference numerals as those in the first embodiment, and description thereof will be omitted.

That is, in FIG. 9, reference numeral 51 indicates a capacitor element in the pressure detecting portion 1, one electrode 52 is an odd number (three in the figure), and the counter electrode 53 of this electrode 52 is an even number. It is formed by stacking one sheet (four sheets in the figure).

In the circuit, the even-numbered counter electrodes 53 having a large number are connected to the low voltage side (ground side), and the odd-numbered electrodes 52 having a small number are connected to the high voltage side (hot side). Has been done.

With such a structure, the shield effect can be remarkably improved, and the data having more stable and improved reproducibility can be obtained in the frequency band (several 100 Hz to several MHz) in which the capacitor element is actually used. Can be obtained.

If the fifth embodiment is also applied to the second embodiment, the third embodiment and the fourth embodiment, the shielding effect can be remarkably improved. The rest of the configuration, functions and effects are the same as those of the first embodiment, so description thereof will be omitted.

[0059]

As described above, according to the present invention, in the electrostatic capacity type force sensor for measuring the pressure by obtaining the change of the electrostatic capacity according to the applied pressure of the capacitor element of the pressure detecting portion, It is possible to increase the capacity and downsize the pressure detection unit.

[Brief description of drawings]

FIG. 1 is an explanatory view of a structure of a capacitor element of a capacitance type force sensor according to a first embodiment of the present invention.

FIG. 2 is a schematic explanatory diagram of a circuit configuration of a capacitance type force sensor according to a first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a configuration of a pressure detection unit of the capacitance type force sensor according to the first embodiment of the present invention.

FIG. 4 is an explanatory view showing a method of connecting the electrode portion and the lead wire of the capacitor element according to the first embodiment of the present invention.

FIG. 5 is an explanatory view showing the connection between the electrode portion and the lead wire of the capacitor element according to the first embodiment of the present invention.

FIG. 6 is an explanatory view showing a capacitor element of a capacitance type force sensor according to a second embodiment of the present invention.

FIG. 7 is an explanatory view showing a capacitor element of a capacitance type force sensor according to a third embodiment of the present invention.

FIG. 8 shows a capacitor element of a capacitance type force sensor according to a fourth embodiment of the present invention, (a) is an explanatory view of the structure of the capacitor element, and (b) is wrapped in an elastic dielectric of the capacitor element. Perspective view of electrode (electrode layer with elastic dielectric)

FIG. 9 shows a capacitor element of a capacitance type force sensor according to a fifth embodiment of the present invention, (a) is an explanatory view of the structure of the capacitor element, and (b) is an explanatory view of the arrangement of electrodes.

[Explanation of symbols]

 1 Pressure Detector 4 Capacitor Element 13 Electrode 14 Elastic Dielectric 15 Electrode C Capacitance F Pressure

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Eiji Sasaki 1938 Nishi Minowa, Ina City, Nagano Prefecture 1938 Rubicon Co., Ltd. Electronic Co., Ltd.

Claims (5)

[Claims] 1. A capacitance type force sensor for measuring a pressure by obtaining a change in capacitance with a pressure applied to a capacitor element of a pressure detection section, wherein an elastic force is applied between opposing electrodes of the capacitor element by pressurization. An electrostatic capacitance type force sensor characterized in that a changing elastic dielectric is interposed. 2. A capacitance type force sensor for measuring a pressure by obtaining a change in capacitance due to a pressure applied to a capacitor element of a pressure detecting section, wherein a capacitance sensor measures the pressure between opposing electrodes of the capacitor element against temperature rise. A capacitance type force sensor is characterized in that an elastic dielectric body whose dielectric constant increases and a elastic dielectric body whose dielectric constant decreases with temperature rise are interposed. 3. A capacitance type force sensor for measuring a pressure by obtaining a change in capacitance due to a pressure applied to a capacitor element of a pressure detecting section, wherein an elastic force is applied between opposing electrodes of the capacitor element by pressurization. A plurality of laminated elastic dielectrics are interposed,
An electrostatic capacitance type force sensor, wherein the capacitor element is formed such that the number of laminated layers of one electrode is different from the number of laminated layers of the other electrode. 4. A capacitance type force sensor for measuring a pressure by obtaining a change in capacitance with a pressure applied to a capacitor element of a pressure detecting section, wherein an elastic force is applied between opposing electrodes of the capacitor element by pressurization. An electrostatic capacitance type force sensor comprising a changing elastic dielectric and a buffer amplification layer for adjusting a change in electrostatic capacitance with respect to a pressing force. 5. A capacitance type force sensor for measuring a pressure by obtaining a change in capacitance due to a pressure applied to a capacitor element of a pressure detecting section, wherein an elastic force is applied between opposing electrodes of the capacitor element by pressurization. A plurality of laminated elastic dielectrics are interposed,
It is characterized in that each of the above-mentioned counter electrodes extends in the direction of each of the terminals on each side, and each of the bonding electrode surfaces that are superposedly bonded to each of the terminals is formed so that the area becomes smaller as the terminals are stacked outward from the respective terminals. Capacitive force sensor.