JP2002257655A - Capacitance type force sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a capacitance type force sensor which is difficult to be affected by a dust or the like and small in volume. SOLUTION: An electrode section C is formed on a plate-like electrode plate 1 having a shaft section 10 at the center region, and electrode sections Cx+, Cx-, Cy+, Cy-are formed on a plate-like electrode plate 3 opposite to the electrode plate 1. The force sensor can detect the magnitude and direction of external forces acting on the shaft section 10 on the basis of the change of capacitance caused by the change of gap at each position between the electrode section C and the electrode sections Cx+, Cx-, Cy+, Cy-. The force sensor is formed in a mode by adhesive bonding so that a thin elastic body is sandwiched between the electrode plate 1 and the electrode plate 3 to have an integral structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a force sensor, and more particularly to a capacitance type force sensor.

[0002]

2. Description of the Related Art FIG. 10 shows an example of this type of capacitance type force sensor.

As shown in FIG. 1, this force sensor has a diaphragm portion 90 which is a deformable portion at the center and a shaft 91 at the center of the diaphragm portion 90.
a, and a lid 9b attached to the strain body 9a in a substantially airtight state. A sealed chamber K is formed between the base strain body 9a and the lid 9b, and in the sealed chamber K, The electrode plate 1 is provided on the strain body 9a side, and the insulating plate 94 is provided on the lid body 9b side.
And the electrode plate 3 is attached to each of them. An electronic device 92 is mounted on the outer wall of the lid 9b via a mounting table 93.
A cap 9c is attached so as to surround the electronic device 92.

An electrode portion is provided on each of the opposing surfaces of the electrode plate 1 and the electrode plate 3. Specifically, as shown in FIG. 11, an electrode portion C is provided on the electrode plate 1 side, and FIG. As shown, on the electrode plate 3 side, electrode portions Cx +, Cx-, Cy +, C
y− and Cz are provided respectively.

The above-described electronic device 92 includes an electrode plate 1,
3, the electrode section C and the electrode section Cx +, the electrode section C and the electrode section Cx-, the electrode section C and the electrode section Cy +, and the electrode section C and the electrode section Cy accompanying the change of the gap G between the three.
-A change in capacitance between the electrodes and between the electrode portion C and the electrode portion Cz is converted into a change in voltage.

Since the capacitance type force sensor is configured as described above, the magnitude and direction of the force acting on the shaft 91 can be detected.

However, this force sensor is bulky because the strain body 9a and the lid 9b each have a so-called three-dimensional structure, and air exists between the electrode plates 1 and 3. It is susceptible to trash.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a capacitance type force sensor which is hardly affected by dust and the like and has a low bulk.

[0009]

Means for Solving the Problems (Invention of Claim 1)
The capacitance type force sensor of the present invention has a shaft 10 at the center.
An electrode portion C is formed on a flat electrode plate 1 having
An electrode portion Cx is provided on the flat electrode plate 3 facing the electrode plate 1.
+, Cx-, Cy +, Cy- are formed, and the electrode portion C
A force sensor capable of detecting the magnitude and direction of the 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 portion Cx +, Cx−, Cy +, and Cy−. The electrode plate 1 and the electrode plate 3 have an integrated adhesive structure in which the thin elastic body 2 is sandwiched between the electrode plates 1 and 3. (Invention of Claim 2) The capacitive force sensor according to the present invention relates to the invention of Claim 1, when the shaft portion 10 is tilted, the thickness d of the elastic body 2 is reduced. On the side, the thickness becomes d−Δd due to the compressive force from the electrode plates 1 and 3, and on the opposite side, the thickness becomes d + Δd due to the tensile force from the electrode plates 1 and 3.

[0010]

The present invention operates as follows.

The electrode plate 1 and the electrode plate 3 do not have a three-dimensional structure, but are interposed between them, and the other elastic body 2 is set to be thin. Become.

Further, since a thin elastic body 2 is interposed between the electrode plate 1 and the electrode plate 3 in such a manner as to be in close contact with them, as in the force sensor described in the section of the prior art, the thin elastic body 2 is used to remove dust and the like. Not affected at all.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the drawings showing embodiments.

The capacitance type force sensor of this embodiment is
As shown in FIGS. 1 and 2, a flat electrode plate 1 having a shaft portion 10 at a central portion, a flat electrode plate 3 disposed opposite to the electrode plate 1, It comprises a thin elastic body 2 interposed between the electrode plates 3 and an electronic device 4 arranged on the electrode plate 3.

The electrode plate 1 has a base made of a circular synthetic resin plate (not limited to this, but may be a metal plate). As shown in FIG. Electrode part C
2, and a thin shaft 5 made of a synthetic resin and having a male screw portion 50 is provided on the same surface as the electrode portion C, as shown in FIG.

The electrode plate 3 is made of the same synthetic resin plate as the above-mentioned electrode plate 1. As shown in FIG. 6, electrode portions Cx + and Cx formed by dividing a circle into four parts on the surface side facing the electrode plate 1.
−, Cy +, Cy−, and an insertion hole 30 through which the fine shaft 5 is inserted is formed as shown in FIG.

The elastic body 2 is made of a silicon rubber plate having a through hole 20 in the center, and elastically deforms as the electrode plates 1 and 3 approach and separate from each other as shown in FIGS. I have to do it. As the elastic body 2 is an insulator and has a higher dielectric constant, the capacitance between the electrode plates 1 and 3 increases, and the elastic body 2 is less susceptible to disturbance due to stray capacitance or the like.

The electronic device 4 is provided between the electrode portion C and the electrode portion Cx + due to a change in the gap between the electrode plates 1 and 3.
Between electrode part C and electrode part Cx-, between electrode part C and electrode part C
A change in capacitance between y + and between the electrode portion C and the electrode portion Cy− is converted into a change in voltage.

Then, as shown in FIG. 2, the fine shaft 5 provided on the electrode plate 1 is inserted through the insertion hole 20 of the elastic body 2 and the insertion hole 30 of the electrode plate 3, and in this state, the fine shaft 5 The nuts 51 are screwed into the male screw portions 50 of the elastic member 2 so that the electrode plates 1 and 3 and the elastic body 2 are in close contact with each other.

Since the force sensor of this embodiment is constructed as described above, it operates as follows. [When an external force acts from a direction perpendicular to the axis of the shaft portion 10] As shown in FIG. 3, the elastic body 3 is deformed (the thickness d is partially changed to d−Δd or d + Δd) and the electrode portion C is deformed. Between electrode part Cx +, electrode part C and electrode part C
The capacitance of each part between x-, between the electrode part C and the electrode part Cy +, between the electrode part C and the electrode part Cy- changes, and the change in the capacitance is caused by the change in the voltage by the electronic device 4. Is converted to [When an external force acts in the axial direction of the shaft portion 10] As shown in FIG. 4, the elastic body 3 is deformed (the thickness d is entirely d−Δd).
The electrode section C and the electrode section Cx +, between the electrode section C and the electrode section Cx-, between the electrode section C and the electrode section Cy +, and between the electrode section C and the electrode section Cy-. , And the change in the capacitance is converted by the electronic device 4 into a change in voltage.

That is, the capacitance of each component is represented by Cx +, Cx
−, Cy +, Cy−, and the values converted to voltages are Vx +,
If Vx−, Vy +, Vy−, Mx = (Vx +) −
(Vx−), My = (Vy +) − (Vy−), Fz =
External force can be detected as an electric signal 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.

And, in this capacitance type force sensor,
As described in the above-mentioned section of the operation, it is less susceptible to dust and the like and has a low bulk.

In the above embodiment, the close sandwich structure between the electrode plates 1 and 3 and the elastic body 2 is changed to the male screw portion 50 of the fine shaft 5.
It is performed by screwing the nut 51 with the nut 51 (screw structure), but is not limited thereto, and may be performed by a crimping structure as shown in FIG. Further, instead of the screwing structure and the crimping structure as described above, the electrode plates 1 and 3 and the elastic body 2 can be formed into an integral structure using an adhesive 8 as shown in FIG.

[0024]

Since the present invention has the above configuration, it has the following effects.

As is clear from the description in the column of operation, it was possible to provide a capacitance type force sensor which is hardly affected by dust and the like and has a low bulk.

[Brief description of the 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 cross-sectional view of the capacitance type force sensor.

FIG. 3 is a diagram showing a state in which an external force acts on the capacitive force sensor from a direction perpendicular to an axis of a shaft.

FIG. 4 is a diagram showing a state in which an external force acts in an axial direction of a shaft portion in the capacitance type force sensor.

FIG. 5 is a diagram showing an electrode part 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 embodiment of the electrode unit.

FIG. 8 is a cross-sectional view of a first capacitive 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 embodiment.

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

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

FIG. 12 is a diagram illustrating an electrode portion of the other electrode plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrode plate 2 Elastic body 3 Electrode plate 10 Shaft part

Claims (2)

[The claims] 1. An electrode portion C is formed on a flat electrode plate 1 having a shaft portion 10 at a central portion, and electrode portions Cx + and Cx− are formed on a flat electrode plate 3 opposed to the electrode plate 1. , Cy +,
Cy− is formed, and the electrode portion C and the electrode portions Cx +, Cx
A force sensor capable of detecting the magnitude and direction of an external force acting on the shaft section 10 by a change in capacitance caused by a change in a gap at each position between −, Cy + and Cy−, wherein A capacitance type force sensor having an integrated adhesive structure in which a thin elastic body 2 is sandwiched between a plate 1 and an electrode plate 3. 2. When the shaft portion 10 is tilted, the elastic member 2
The thickness d of the shaft portion 10 becomes the thickness d−Δd by the compressive force from the electrode plates 1 and 3 on the side where the shaft portion 10 is tilted, and the thickness d + Δd by the tensile force from the electrode plates 1 and 3 on the opposite side. The capacitance type force sensor according to claim 1, wherein: