JPH06201491A - Electrostatic capacitance type force sensor - Google Patents

Abstract

PURPOSE:To provide an electrostatic capacitance type force sensor which is not likely to be affected by dust or the like and is not bulky. CONSTITUTION:This is a force sensor for detecting magnitude and a direction of external force functioning to a shaft 10 by a change in electrostatic capacitance caused by a change in gaps at respective positions between a flat plane electrode plate 1 having the shaft 10 at the center and a flat plane electrode plate 3 facing the electrode plate 1, wherein a thin elastic body 2 is interposed between the electrode plates 1, 3 in tight contact with them.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to force sensors, and in particular to
The present invention relates to a capacitance type force sensor.

[0002]

2. Description of the Related Art As an electrostatic capacitance type force sensor of this type, for example, there is one shown in FIG. As shown in the same figure, this force sensor has a strain-flexing body 9a having a diaphragm portion 90 serving as a deformable portion at the center and a shaft portion 91 at the center of the diaphragm portion 90, and the strain-flexing body 9a.
And a lid 9b attached in a substantially airtight state to form a sealed chamber K between the strain-flexing body 9a and the lid 9b, and in the sealed chamber K, an electrode is provided on the strain-generating body 9a side. The plate 1 is configured such that the electrode plate 3 is attached to the lid 9b side via an insulating plate 94. An electronic device 92 is attached to the outer wall of the lid 9b via a mounting base 93, and a cap 9c is mounted so as to surround the mounting base 93 and the electronic device 92.

Electrode portions are provided on the opposing surfaces of the electrode plate 1 and the electrode plate 3, respectively. Specifically, as shown in FIG. 11, an electrode portion C is provided on the side of the electrode plate 1, and FIG. As shown in the drawing, the electrode parts Cx +, Cx-, Cy +, C are provided on the side of the electrode plate 3.
y- and Cz are provided respectively. In the electronic device 92 described above, the electrode portion C and the electrode portion Cx + are connected to each other as the gap G between the electrode plates 1 and 3 is changed, the electrode portion C and the electrode portion Cx− are connected to each other, and the electrode portion C and the electrode portion are connected to each other. Between Cy +,
A change in capacitance between the electrode portion C and the electrode portion Cy- and between the electrode portion C and the electrode portion Cz is converted into a change in voltage.

Since this capacitance type force sensor is constructed as described above, the magnitude and direction of the force acting on the shaft portion 91 can be detected. However, this force sensor
Since the strain generating body 9a and the lid body 9b each have a so-called three-dimensional structure, it becomes bulky.
Since air exists between the three, it is easily affected by dust and the like.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a capacitance type force sensor which is not easily affected by dust and the like and has a low bulk.

[0006]

A capacitance type force sensor according to the present invention is a flat plate-shaped electrode plate 1 having a shaft portion 10 in the center and a flat plate-shaped electrode plate facing the electrode plate 1. Is a force sensor capable of detecting the magnitude and direction of an external force acting on the shaft portion 10 by a change in capacitance caused by a change in a gap at each position between the electrode plate 1 and the electrode plate 1. A thin elastic body 2 is interposed between the electrode plate 3 and the electrode plate 3 in such a manner that they are brought into close contact with them.

[0007]

The present invention has the following actions. The electrode plate 1 and the electrode plate 3 do not have a three-dimensional structure, and the elastic body 2 interposed between them is set to be thin, so that the electrode plate 1 and the electrode plate 3 are much less bulky than the conventional force sensor.

Further, since the thin elastic body 2 is interposed between the electrode plate 1 and the electrode plate 3 in such a manner that they are brought into close contact with them, like the force sensor described in the section of the prior art, dust or the like is removed. Not affected at all.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described below with reference to the drawings shown as embodiments. As shown in FIG. 1 and FIG. 2, the electrostatic capacitance type force sensor of this embodiment has a flat plate-shaped electrode plate 1 having a shaft portion 10 in the central portion, and a flat plate arranged opposite to the electrode plate 1. Electrode plate 3, a thin elastic body 2 interposed between the electrode plate 1 and the electrode plate 3, and an electronic device 4 arranged on the electrode plate 3.

The electrode plate 1 is composed of a circular synthetic resin plate (not limited to this, a metal plate may be used) as a base material, and as shown in FIG. 5, a circular shape is formed on the side facing the electrode plate 3. Electrode part C
2 is printed, and a thin shaft 5 made of synthetic resin having a male screw portion 50 is provided on the same side as the electrode portion C as shown in FIG. The electrode plate 3 is composed of the same synthetic resin plate as the electrode plate 1, and as shown in FIG. 6, electrode portions Cx +, Cx formed by dividing a circle into four on the side facing the electrode plate 1.
-, Cy +, Cy- are printed, and an insertion hole 30 through which the thin shaft 5 is inserted is formed as shown in FIG.

The elastic body 2 is composed of a silicon rubber plate having an insertion hole 20 in the center thereof, and as shown in FIGS. 3 and 4, elastically deforms as the electrode plates 1 and 3 approach and separate from each other. I am doing it. As the elastic body 2 is made of an insulating material and has a large dielectric constant, the electrostatic capacitance between the electrode plates 1 and 3 is large, and the elastic body 2 is less likely to be disturbed by stray capacitance or the like. The electronic device 4 includes the electrode portion C and the electrode portion Cx +, and the electrode portion C and the electrode portion Cx according to the change in the gap between the electrode plates 1 and 3.
-Changes in electrostatic capacitance between the electrodes, between the electrode portion C and the electrode portion Cy +, and between the electrode portion C and the electrode portion Cy- are converted into changes in the voltage.

Then, as shown in FIG. 2, the thin shaft 5 provided on the electrode plate 1 is inserted into the insertion hole 20 of the elastic body 2 and the insertion hole 30 of the electrode plate 3, and in this state, the thin shaft 5 is inserted. A nut 51 is screwed into the male screw portion 50 of FIG. 2 to bring the electrode plates 1 and 3 and the elastic body 2 into close contact with each other. Since the force sensor of this embodiment is constructed as described above, it works as follows. [External force acts from the direction perpendicular to the axis of the shaft portion 10
Case] As shown in FIG. 3, the elastic body 3 is deformed (the thickness d is deformed to d-Δd or d + Δd depending on the portion) so that the electrode portion C and the electrode portion Cx + are mutually connected, and the electrode portion C and the electrode portion C are formed.
The capacitance of each portion between x−, between the electrode portion C and the electrode portion Cy +, and between the electrode portion C and the electrode portion Cy− changes, and this change in the capacitance is caused by a change in the voltage by the electronic device 4. Is converted to. [When external force acts in the axial direction of the shaft portion 10] As shown in Fig. 4, the elastic body 3 is deformed (thickness d is d-Δd as a whole ) .
To the electrode portion C and the electrode portion Cx +, between the electrode portion C and the electrode portion Cx−, between the electrode portion C and the electrode portion Cy +, and between the electrode portion C and the electrode portion Cy−. Of the capacitance changes, and the change in capacitance is converted into a change in voltage by the electronic device 4.

That is, the capacitance of each component is represented by Cx +, Cx
−, Cy +, Cy−, and the value converted into voltage is Vx +,
If Vx−, Vy +, Vy−, then Mx = (Vx +) −
(Vx−), My = (Vy +) − (Vy−), Fz =
External force can be detected as an electric signal such as (Vx +) + (Vx −) + (Vy +) + (Vy−). As shown in FIG. 7, when the electrode portion Cz is added to the electrode plate 3, Fz =
(Vx +) + (Vx −) + (Vy +) + (Vy−) or Vz.

Then, in this capacitance type force sensor,
As described in the above-mentioned action column, it is less susceptible to dust and the like and has a low bulk. In the above embodiment, the contact sandwich structure between the electrode plates 1 and 3 and the elastic body 2 is formed by screwing the male screw portion 50 of the thin shaft 5 and the nut 51 (screw fixing structure). However, as shown in FIG. 8, it may be formed by a caulking stop structure. Further, as shown in FIG. 9, the electrode plates 1 and 3 and the elastic body 2 may be made into an integral structure by using an adhesive material 8 instead of the screw fastening structure or the crimp fastening structure as described above.

[0015]

Since the present invention has the structure as described above, it has the following effects. From the contents described in the section of action, it was possible to provide a capacitance type force sensor that is not easily affected by dust and the like and has a low bulk.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of a capacitance type force sensor according to an embodiment of the present invention.

FIG. 2 is a sectional view of the capacitance type force sensor.

FIG. 3 is a diagram showing a state of the capacitance type force sensor when an external force is applied from a direction perpendicular to an axis of a shaft portion.

FIG. 4 is a view showing a state of the electrostatic capacitance type force sensor when an external force is applied in the axial direction of the shaft portion.

FIG. 5 is a diagram showing an electrode portion of one electrode plate in the capacitance type force sensor.

FIG. 6 is a diagram showing an electrode portion of the other electrode plate in the capacitance type force sensor.

FIG. 7 is a diagram showing another mode of the electrode portion.

FIG. 8 is a sectional view of a first electrostatic capacity type force sensor having a structure different from that of the embodiment.

FIG. 9 is a cross-sectional view of a second capacitive force sensor having a structure different from that of the above-described embodiment.

FIG. 10 is a cross-sectional view of a conventional capacitive force sensor.

FIG. 11 is a view showing an electrode portion of one electrode plate.

FIG. 12 is a view showing an electrode portion of the other electrode plate.

[Explanation of symbols]

 1 Electrode plate 2 Elastic body 3 Electrode plate 10 Shaft part

Claims (1)

[Claims] 1. A gap at each position between a flat plate-like electrode plate (1) having a shaft portion (10) in the center and a flat plate-like electrode plate (3) facing the electrode plate (1). A force sensor capable of detecting the magnitude and direction of an external force acting on the shaft portion (10) by a capacitance change caused by a change in the electrode plate (1) and the electrode plate (3). A capacitive force sensor, characterized in that a thin elastic body (2) is interposed between them in such a manner that they are brought into close contact with them.