JPH10148503A - Capacitance displacement sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a capacitance displacement sensor by which relative displacement amount can be detected on the basis of the ratio of capacitances by arranging opposed electrode pairs in such a way that, when the capacitance of one side is increased, the capacitance of the other side is decreased, and detecting the capacitances of the electrode pairs. SOLUTION: First stator electrode plates 6 and second stator electrode plates 7 are arranged in the transverse direction with reference to the displacement direction of an actuator, and first mover electrode plates 8 and second mover electrode plates 9 are arranged alternately. A first electrode pair 10 is formed of the first stator electrode plates 6 and of the first mover electrode plates 8 which are faced, a second electrode pair 11 is formed of the second stator electrode plates 7 and of the second mover electrode plates 9, and the first electrode pair 10 and the second electrode pair 11 are formed as a pair. Both electrode pairs are arranged in such a way that, when the capacitance of the pair on one side is increased, the capacitance of the pair on the other side is decreased. The respective capacitances of the first electrode pair 10 and the second electrode pair 11 are detected, their ratio is found, and a relative displacement amount is computed. Thereby, the influence of a permittivity is offset, and the displacement amount can be detected without being influenced by a temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a displacement sensor for detecting a displacement of an electrostatic actuator or the like.

[0002]

2. Description of the Related Art Conventionally, there has been the following capacitive displacement sensor for detecting a displacement amount of an electrostatic actuator or the like.

This capacitance displacement sensor detects a capacitance that changes with a change in an overlapping area between opposing electrode pairs disposed on respective substrates of an electrostatic actuator or the like, and calculates a relative displacement amount based on the capacitance. What you want to do.

However, the capacitive displacement sensor is susceptible to a temperature change due to an insulating material interposed between the electrode pairs.
Therefore, there is a problem that an error easily occurs between the actual value and the actual value.

[0005]

SUMMARY OF THE INVENTION Therefore, the present invention
An object of the present invention is to provide a capacitance displacement sensor that is less susceptible to a temperature change than before.

[0006]

In order to solve the above-mentioned problems, the present invention employs the following technical means.

The capacitive displacement sensor according to the present invention includes an opposed electrode pair for detecting a relative displacement and forms a pair with the electrode pair, and the electric pair forms a pair in the direction of relative displacement. When the electrode pair the capacitance C ₁ of the one of which made braided increases, the other of the electrode pairs occupies assembled the pairs are brought arranged such that the positional relationship to decrease the capacitance C _2, opposite , The capacitance C ₁ ,
Detecting a C _2, characterized in that to calculate the relative displacement from the ratio of the capacitance.

When an insulating material such as oil is interposed between the pair of electrodes, and the insulating material is a dielectric material having a dielectric constant ε, the capacitance C becomes the dielectric constant ε, the facing area S, and the facing distance d.
And C = ε · S / d, and the dielectric constant ε that changes when the temperature or room temperature changes is related to the capacitance C.

In this capacitance displacement sensor, when one of the paired electrode pairs has an increased capacitance C ₁ in the direction in which the electric pair is relatively displaced, the electric pair of the paired electrode pairs is increased. other since been brought arranged such that the positional relationship to decrease the capacitance C _2, it is possible to take the ratio of the capacitance C ₁ and the capacitance C _2.

[0010] That is, to detect the capacitances C _1, C ₂ of the pair of opposing electrodes of the pair, since to calculate the relative displacement from the ratio of the capacitance, the capacitance C ₁ and the electrostatic becomes the same permittivity ε relative capacitances C _1, C ₂ both by taking the ratio of the capacitance C ₂ disappears by the numerator and denominator, thereby the dielectric constant is a key factor that governs the temperature characteristics ε The effects of can be offset.

[0011] The electrode pair may be formed on a film substrate.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 5 show an electrostatic film actuator composed of a pair of upper and lower film substrates, which comprises a sensor section 1 in an end region and a known electrostatic actuator section 2. FIG. That is, in this embodiment, a capacitive displacement sensor is formed in the sensor unit 1 in the end region of the electrostatic film actuator.

The film substrate has a lower stator 3 (see FIG. 1) and an upper mover 4 (see FIG. 2). The electrode terminals of the stator 3 and the electrostatic actuator 2 of the mover 4 are provided. 5 is supplied with a voltage by a known method.

The capacitive displacement sensor in the end region of the film substrate has opposed electrode pairs for detecting the relative displacement of the actuator, and these electrode pairs are assembled into pairs. Between the pair of electrodes of the opposing film substrate,
Insulating oil is interposed.

In this embodiment, a pair of electrode pairs arranged in the direction in which the actuator is displaced is assembled in the sensor section 1 of the film substrate of the stator 3 and the moving element 4. That is, the sensor portion 1 of the film substrate of the stator 3 is provided with a stator first electrode plate 6 and a stator second electrode plate 7 each composed of two electrode plates.
The sensor part 1 of the film substrate is provided with a movable element first electrode plate 8 and a movable element second electrode plate 9 similarly composed of two electrode plates.

Stator first electrode plate 6 and stator second electrode plate 7
Are provided at positions that are arranged side by side with respect to the direction in which the actuator is displaced. On the other hand,
The electrode plate 8 and the movable element second electrode plate 9 are provided at alternate positions with respect to the direction in which the actuator is displaced.

Then, a first electrode pair 10 is formed from the opposed stator first electrode plate 6 and the movable element first electrode plate 8, and the opposed stator second electrode plate 7 and the movable element second electrode are similarly formed. The second electrode pair 11 is formed from the plate 9, and the first electrode pair 10 and the second electrode pair 11 are further formed.
A pair is formed between the electrode pair and the electrode pair 11.

When the capacitance C _{1 of one} of the paired electrode pairs increases in the direction in which the electric pair is relatively displaced, the other of the paired electrode pairs becomes the capacitance. _They are arranged so as to have a positional relationship in which C ₂ decreases.

Next, the use state of the capacitance displacement sensor of this embodiment will be described. FIG. 3 shows a state in which the film substrate of the stator 3 and the film substrate of the moving element 4 are overlapped so that the outer circumferences thereof coincide. The illustration of the printed electrode wiring of the film substrate and the wiring to the electrode terminals 5 of the film substrate are omitted.

The hatching of the electrode plates is from the upper right to the lower left for the stator 3 and the hatching for the mover 4 is from the upper left to the lower right. When the electrode plates are overlapped, they are shown in an oblique mesh shape due to the overlap of hatching.

In the state shown in FIG. 3, the opposed first stator
Both of the two electrode plates of the first electrode pair 10 formed of the electrode plate 6 and the mover first electrode plate 8 overlap, and similarly, the opposed stator second electrode plate 7 and mover second electrode plate 9 are in a state of being shifted from each other. Therefore, the capacitance C ₁ of the first electrode pair 10 is the maximum value, and the capacitance C ₂ of the second electrode pair 11 is zero.

FIG. 4 shows a state in which the film substrate of the moving member 4 is displaced leftward in the drawing by one pitch of the electrode plate with respect to the film substrate of the stator 3 from the state of FIG. The first electrode pair 10 formed by the opposed stator first electrode plate 6 and the movable element first electrode plate 8 is staggered, and the opposed stator second electrode plate 7 and the movable element second electrode The second electrode pair 11 formed from the plate 9 is in a state where both of the two electrode plates overlap.

The state shown in FIG. 3 is displaced to the state shown in FIG.
In the process, the capacitance C of the first electrode pair 10, which was the maximum value,₁But
The capacitance of the second electrode pair 11 was reduced to zero and was zero.
Quantity C _TwoHas increased to the maximum value.

FIG. 5 shows a state in which the film substrate of the moving element 4 is displaced from the state of FIG. 3 by one pitch of the electrode plate to the right in the drawing with respect to the film substrate of the stator 3. The first electrode pair 10 formed by the opposed stator first electrode plate 6 and the movable element first electrode plate 8 is staggered, and the opposed stator second electrode plate 7 and the movable element second electrode The second electrode pair 11 formed from the plate 9 is in a state where only one of the two electrode plates overlaps.

The state shown in FIG. 3 is changed to the state shown in FIG.
In the process, the capacitance C of the first electrode pair 10, which was the maximum value,₁But
The capacitance of the second electrode pair 11 was reduced to zero and was zero.
Quantity C _TwoHas increased to half the maximum value.

Then, the capacitances C ₁ and C ₂ of the pair of opposing electrode pairs are detected, and the ratio of the capacitances is calculated by a known method using a signal circuit shown in FIG. 6 to calculate the relative displacement. I am trying to do it.

According to this capacitance displacement sensor, the capacitances C ₁ and C ₂ of the pair of opposing electrode pairs are detected, and the relative displacement is calculated from the ratio of the capacitances. the main factors C ₁ and the same dielectric constant for both capacitances C _1, C ₂ by taking the ratio of the capacitance C ₂ epsilon becomes disappear in the numerator and denominator, thereby governing the temperature characteristic Since the relative displacement can be calculated by canceling out the influence of the dielectric constant ε, there is an advantage that it is less susceptible to a temperature change than in the past.

That is, according to this embodiment, a capacitance displacement sensor having a displacement detection function on the film substrate of the electrostatic film actuator and being hardly affected by a temperature change can be constructed.

[0030]

The present invention is configured as described above and has the following effects.

The dielectric constant ε which is a main factor controlling the temperature characteristics
Can be canceled out, it is possible to provide a capacitive displacement sensor that is less susceptible to a temperature change than in the past.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a film substrate of a lower stator of an embodiment of a capacitive displacement sensor of the present invention.

FIG. 2 is an explanatory view of a film substrate of an upper stator of the capacitive displacement sensor of FIG. 1;

FIG. 3 is an explanatory diagram showing a state in which the film substrate of the stator shown in FIG. 1 and the film substrate of the movable member shown in FIG.

4 is an explanatory view showing a state in which the film substrate of the moving element of FIG. 2 is displaced leftward in the drawing by one pitch of the electrode plate with respect to the film substrate of the stator of FIG. 1 from the state of FIG.

5 is an explanatory diagram showing a state in which the film substrate of the moving element of FIG. 2 is displaced leftward in the drawing by one pitch of the electrode plate from the state of FIG. 3 with respect to the film substrate of the stator of FIG. 1;

FIG. 6 is a circuit diagram for performing arithmetic processing from a detected value of capacitance.

[Explanation of symbols]

 10 electrode pairs 11 electrode pairs

Claims (2)

[Claims] An electrode pair for detecting a relative displacement, and a pair formed by the electrode pairs;
To the direction of the electric pairs relative displacement, when the capacitance C ₁ of one of the electrode pairs occupies assembled pairs increases, the other of the electrode pairs occupies assembled a pair capacitance C ₂ It is arranged so as to have a decreasing positional relationship, the capacitances C ₁ and C ₂ of the pair of opposing electrode pairs are detected, and the relative displacement is calculated from the ratio of the capacitances. And a displacement sensor. 2. The capacitive displacement sensor according to claim 1, wherein the electrode pair is formed on a film substrate.