JP2001074771A - Electrostatic torquer type accelerometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a torquer electrode against welding or damage and to prevent a mass body from sticking to a fixed electrode plate. SOLUTION: Stoppers 31 are projected from the opposite plate faces of a planar mass body 11 such that they are positioned on an axis perpendicular to a plate face passing through the center of gravity G of the mass body 11 supported displaceably by a hinge 12. Capacitance detecting electrodes 21 are provided on the top surface of the stoppers 31 and plate surface torquer electrodes 22 are provided except the stopper 31 forming part of the mass body 11. Even if an undue displacement is generated in the mass body 11, the stopper 31 touches a fixed electrode plate 14 to avoid contact of the torquer electrodes 22, 23. Furthermore, sticking can be prevented because the stopper 31 can decrease the contact area when the mass body 11 touches the fixed electrode plate 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a closed-loop type accelerometer using an electrostatic torquer, and more particularly to a method for preventing damage to a torquer electrode and sticking of a mass body having a pendulum structure to a fixed electrode plate. Regarding the structure.

[0002]

2. Description of the Related Art FIG. 9 shows an example of a conventional structure of an electrostatic torquer type accelerometer. One end side of the plate-shaped mass body 11 is supported by a frame body 13 by a hinge 12 so as to be displaceable, and two fixed electrode plates 14 are arranged facing both plate surfaces of the mass body 11. ing. Mass 11
The movable electrodes 15 are provided on both plate surfaces, respectively.
A fixed electrode 16 facing the movable electrode 15 is provided on each of the two fixed electrode plates 14.

When an acceleration is applied from the outside, the mass body 11 is displaced in accordance with the input acceleration, and the displacement changes the capacitance of the upper and lower capacitors formed by the movable electrode 15 and the fixed electrode 16. . The amount of displacement of the mass body 11 is detected as a difference between the capacitances of these two capacitors, and a static voltage formed by applying a voltage between the two sets of the movable electrode 15 and the fixed electrode 16 based on the detected output. A feedback loop is formed by the electric torquer mechanism so as to generate a force in the direction of returning the mass body 11 to the neutral position.

[0004] In this example, the movable electrode 15 and the fixed electrode 16 form an electrode pair for detecting capacitance and also function as an electrode pair for ToruCa. Since the electrostatic torquer mechanism uses an attractive force generated by applying an electric voltage between the fixed electrode and the movable electrode and generated by electrostatic force between the two electrodes, for example, a large shock or vibration is applied from the outside, and the movable electrode When the fixed electrode comes into contact with the fixed electrode, a large current flows through the contacted small area, and both electrodes are welded,
Or a problem such as breakage occurs.

[0005] FIG. 10A shows a method for avoiding such a problem.
This shows a conventionally proposed structure. In this example, the capacitance detection electrode and the Toruca electrode are not the same as described above, but are separated from each other, and are connected to the hinge 12 support side of the mass body 11. Electrode 2 for detecting capacitance is provided on the opposite free end side.
1, and a Toruca electrode 22 is provided on the side closer to the hinge 12.

According to this structure, even if the mass body 11 is largely displaced as shown in FIG. 10B, the Toruca electrode 22 does not contact the Toruca electrode 23 of the fixed electrode plate 14, so that these Toruca electrodes It is possible to prevent welding and breakage of 22, 23. Even if the mass body 11 and the capacitance detecting electrodes 21 and 24 of the fixed electrode plate 14 come into contact with each other, a large current does not flow between the electrodes 21 and 24, that is, like a Toruca electrode. No welding or breakage occurs.

Japanese Unexamined Patent Publication (Kokai) No. Hei 3-146872 discloses that the position of the movable electrode end and the position of the fixed electrode end are prevented in order to prevent the movable electrode and the fixed electrode from causing the above-described welding or breakage. A configuration shifted from the position is described, and this configuration can also avoid contact between the movable electrode and the fixed electrode when a large displacement occurs in the mass body as illustrated in FIG. 10B.

[0008]

As described above, FIG.
If the configuration shown in FIG. 10A or the configuration shown in JP-A-3-146872 is adopted, when the mass body 11 is displaced as shown in FIG.
Contact between the Toruca electrodes can be avoided.

However, when a strong impact or vibration is applied, the hinge 12 does not have the primary bending as shown in FIG. 10B, but the secondary bending (higher bending) as shown in FIG. 10C. When such bending occurs, FIG.
As shown in FIG. 0C, the Toruca electrodes 22 and 23 come into contact with each other, that is, welding or breakage of the electrodes occurs.

On the other hand, another problem of this type of electrostatic torquer accelerometer is that the mass sticks to the fixed electrode plate. This is because the mass body having a good flat surface and the fixed electrode plate face each other with a small gap therebetween. For example, when the mass body is displaced in parallel and comes into contact with the fixed electrode plate in parallel, the surface and the surface are fixed. The mass body sticks to the fixed electrode plate due to friction with the above, and such sticking often occurs, for example, when the power is turned on, and the Toruca electrodes come into contact with each other. In the same way, it causes welding and breakage.

[0011] For example, it is also possible to remove with a force generated by the Toruca electrode on the side opposite to the side to which it is attached.
It is necessary to add an electric circuit having an algorithm for releasing the sticking. In this respect, the configuration becomes complicated, the cost becomes high, and the rise time at the time of turning on the power is delayed. SUMMARY OF THE INVENTION In view of these problems, an object of the present invention is to provide an electrostatic torquer type accelerometer in which welding and breakage of a torquer electrode do not occur and a mass does not stick to a fixed electrode plate. is there.

[0012]

According to the first aspect of the present invention, two fixed electrode plates are disposed opposite to both plate surfaces of a plate-shaped mass body supported so as to be displaceable by a hinge, and these mass bodies are arranged. An electrode pair for capacitance detection and an electrode pair for Toruca are respectively formed between each of the and the two fixed electrode plates, and the displacement of the mass body due to the acceleration input is detected by the change in the capacitance,
Based on the detection output, a voltage is applied to the Toruca electrode pair to return the mass to the neutral position. In an electrostatic Toruca-type accelerometer, the position on the axis perpendicular to the plate surface passing through the center of gravity of the mass Then, stoppers protrude from both plate surfaces of the mass body, and the top surfaces of the stoppers serve as components of the capacitance detection electrode. Toruca electrodes are formed on the plate surface excluding the stopper formation portion of the mass body. Be composed.

According to the second aspect of the present invention, two fixed electrode plates are disposed opposite to both plate surfaces of the plate-shaped mass body displaceably supported by the hinge, and the mass body and the two fixed electrode plates are arranged. A capacitance detecting electrode pair and a Toruca electrode pair are respectively configured between each of the above, and the displacement of the mass body due to the acceleration input is detected by a change in the capacitance, and based on the detected output, the Toruca electrode pair is formed. In an electrostatic torquer accelerometer configured to return a mass to a neutral position by applying a voltage, the mass of both fixed electrode plates is positioned on an axis perpendicular to the plate surface passing through the center of gravity of the mass. Stoppers are formed to project from the plate surfaces facing each other, the top surfaces of the stoppers serve as components of the capacitance detection electrodes, and Toruca electrodes are formed on the plate surfaces of both fixed electrode plates excluding the stopper formation portions. You.

According to the third aspect of the present invention, two fixed electrode plates are arranged opposite to both plate surfaces of the plate-shaped mass body displaceably supported by the hinge, and the mass body and the two fixed electrode plates are arranged. A capacitance detecting electrode pair and a Toruca electrode pair are respectively configured between each of the above, and the displacement of the mass body due to the acceleration input is detected by a change in the capacitance, and based on the detected output, the Toruca electrode pair is formed. In an electrostatic torquer accelerometer configured to apply a voltage to return a mass to a neutral position, a plane that includes the center of gravity of the mass, that is perpendicular to its plate surface, and that is parallel to the bending axis of the hinge is a mass. Stoppers protrude on the lines intersecting the two plate surfaces, and the top surfaces of these stoppers constitute the components of the capacitance detection electrode, and the Toruca electrodes are formed on the plate surface except the stopper formation portion of the mass body. Is done.

According to the fourth aspect of the present invention, two fixed electrode plates are disposed so as to face both plate surfaces of the plate-shaped mass body displaceably supported by the hinge, and the mass body and the two fixed electrode plates are arranged. A capacitance detecting electrode pair and a Toruca electrode pair are respectively configured between each of the above, and the displacement of the mass body due to the acceleration input is detected by a change in the capacitance, and based on the detected output, the Toruca electrode pair is formed. In an electrostatic torquer accelerometer with a structure that applies voltage to return the mass to the neutral position, both planes including the center of gravity of the mass and perpendicular to the plate surface and parallel to the bending axis of the hinge are fixed. Stoppers are respectively formed on lines intersecting the plate surface facing the mass body of the electrode plate, and the top surfaces of the stoppers serve as components of the capacitance detecting electrode, excluding the stopper forming portions of both fixed electrode plates. An electrode for ToruCa is configured on the plate surface .

[0016]

Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows an embodiment of the first aspect of the present invention, and FIG. 2 shows the embodiment in an exploded manner. Parts corresponding to those in FIG. 10 are denoted by the same reference numerals.

In this example, the rectangular plate-shaped mass body 11 has two extremely thin plate-shaped hinges 12 as shown in FIG.
One end of the mass body 11 is supported by the frame body 13 and positioned within the frame of the frame body 13, and both plate surfaces of the mass body 11 are integrally formed with stoppers 31 each having a circular shape and slightly projecting therefrom. I have. These stoppers 31 are
The center of gravity of these two stoppers 31 is coincident with the center of gravity G of the mass body 11 through the center of gravity G of the mass body 11 and perpendicular to both plate surfaces of the mass body 11.

Electrodes 21 for detecting capacitance are provided on the top surface of each stopper 31, respectively. The plate surface of the mass body 11 except for the portion where the stopper 31 is formed surrounds the stopper 31 as shown in FIG. , A Toruca electrode 22 is provided.
The two fixed electrode plates 14 arranged opposite to both plate surfaces of the mass body 11 respectively have a capacitance paired with the capacitance detection electrode 21 and the Toruca electrode 22 provided on the mass body 11. A detection electrode 24 and a Toruca electrode 23 are provided.

The mass body 11, the hinge 12, and the frame 13 are integrally formed by, for example, etching a quartz glass plate, and the two fixed electrode plates 14 are also made of a quartz glass plate. Electrode 21 for capacitance detection
The electrode 4 and the Toruca electrodes 22 and 23 are formed of, for example, an Au deposited film. The required wiring is provided to each of the electrodes 21 to 24 as schematically shown in FIG. Electrode 2 for detecting capacitance generated by displacement of mass body 11 due to acceleration input
The difference between the capacitances of the two sets of capacitors 1 and 24 is detected by the displacement detector 32 as the difference between the amplitude or the phase of the AC voltage applied to both capacitors.

The detection output of the displacement detector 32 is converted into a voltage between the two sets of Toruca electrodes 22 and 23 by a Toruca voltage converter 33 to generate a force in the direction of returning the mass body 11 to the neutral position. Then, a voltage is applied to the two sets of Toruca electrodes 22 and 23. As a result, a feedback loop is formed in which the mass body 11 stops at a position where the force due to the acceleration applied to the mass body 11 and the force generated by the electrostatic torquer mechanism are balanced.

The center of action of the force generated by the electrostatic torquer mechanism and the mass body 1 supported by the hinge 12
The center of action of the damping acting on 1 is configured to coincide with the center of gravity G of the mass body 11. FIG. 3 shows an example of a circuit configuration of a displacement detector 32 that detects displacement based on a change in capacitance. The circuit shown in FIG. 3 captures a difference in capacitance between two sets of capacitors as a difference in amplitude, and outputs a voltage proportional to the displacement in the final stage.

FIG. 4 shows a state where an excessive force is applied to the mass body 11 due to impact or vibration in the electrostatic torquer type accelerometer having the above-described configuration, causing a displacement. FIG. 4A shows the case where the hinge 12 is bent in the first order, and the stopper 31 contacts the fixed electrode plate 14 before the free end of the mass body 11 contacts the fixed electrode plate 14. Contact between the Toruca electrodes 22 and 23 at the free end is prevented. Although the capacitance detecting electrodes 21 and 24 are in contact with each other, an AC voltage is applied to the electrodes 21 and 24 as described above, so that even when the electrodes 21 and 24 come into contact, no overcurrent flows.

FIG. 4B shows a case where a strong force is applied to cause a secondary bending of the hinge 12, and also in this case, the stopper 31 on the center of gravity G comes into contact with the fixed electrode plate 14, whereby The structure for supporting the mass body 11 and the further displacement of the mass body 11 are regulated.
And 23 are prevented from contacting. Since the stopper 31 is provided on the mass body 11 as described above, the contact area between the mass body 11 and the fixed electrode plate 14 can be reduced, so that sticking due to friction between the surfaces is prevented. can do.

In the above-described example, the planar shape of the stopper 31 is circular. However, the shape is not limited to this, and may be, for example, a polygon such as a square. FIG. 5 shows an example in which hinges 12 for supporting the mass body 11 so as to be displaceable are arranged not only on one side (one end side) of the mass body 11 but also on both sides. The body 11 is supported at both ends. In this structure as well, the stopper 31 is provided on both plate surfaces of the mass body 11 as shown in FIG. 2, and the capacitance detecting electrode and the torquer electrode (not shown) are similarly provided. It is possible to prevent contact between them.

FIG. 6 shows an embodiment of the second aspect of the present invention. In this embodiment, the stoppers are provided not on the mass body 11 but on the two fixed electrode plates 14, respectively. . These stoppers 34 are fixed in the state shown in FIG. 6, that is, on the axis passing through the center of gravity G of the mass body 11 and perpendicular to both plate surfaces of the mass body 11 in a state where the mass body 11 is in the neutral position. The electrode plate 14 is integrally formed on the plate surface facing the mass body 11, and has a circular shape like the stopper 31 in this example.

On the top surface of each stopper 34, a capacitance detecting electrode 24 is provided, and each fixed electrode plate 14
The electrode 23 for the torquer is provided
Is provided. On both plate surfaces of the mass body 11, an electrostatic capacitance detecting electrode 21 and a torquer electrode 22 facing the electrostatic capacitance detecting electrode 24 and the torquer electrode 23, respectively, are provided.

According to the configuration shown in FIG. 6, similarly to the electrostatic torquer type accelerometer shown in FIG. 1, when the mass body 11 is excessively displaced, the contact between the torquer electrodes 22 and 23 occurs. Can be avoided, and sticking between the mass body 11 and the fixed electrode plate 14 can be avoided. FIGS. 7 and 8 show other arrangement shapes of the stopper provided on the mass body 11. The stopper 35 in FIG. 7 is a rectangular projection extending between two opposing sides of the mass body 11, and the stopper 36 in FIG. 8 is divided into two parts by removing the central part of the stopper 35 in FIG. It is assumed.

The stoppers 35 and 36 include the center of gravity G of the mass body 11, and a plane perpendicular to both plate surfaces of the mass body 11 and parallel to the bending axis of the hinge 12 intersects with both plate surfaces of the mass body 11. The centers of gravity of the two stoppers 35 arranged on the line and projecting from both plate surfaces of the mass body 11 coincide with the center of gravity G of the mass body 11. Similarly, the center of gravity of the stopper 36 protruded separately at two places on both plate surfaces of the mass body 11 also matches the center of gravity G of the mass body 11.

Although not shown in the drawing, electrodes for detecting the capacitance are formed on the top surfaces of the stoppers 35 and 36 in the same manner as in the above-described example. Is formed. Even if the arrangement of the stoppers provided on the mass body 11 is configured as shown in FIGS. 7 and 8, the same effect as the stopper 31 in FIG. 1 can be obtained.

When a stopper is provided not on the mass body 11 but on the two fixed electrode plates 14 as shown in FIG. 6, these stoppers 35 and 36 are used instead of the circular stopper 34 in FIG. A stopper having an equivalent shape may be provided. In this case, the stopper includes the center of gravity G of the mass body 11, and a plane perpendicular to both plate surfaces of the mass body 11 and parallel to the bending axis of the hinge 12 is a plate surface opposed to the mass body 11 of the fixed electrode plate 14. The projection is formed on the intersecting line.

In the above-described example, the mass body 11, the hinge 12, and the frame 13 are integrally formed by, for example, etching a quartz glass plate, and required electrodes are formed by an Au vapor-deposited film. For example, a mass body, a hinge, and a frame body may be integrally formed using a silicon substrate, and the formation of an electrode film on the mass body may be omitted.

[0032]

As described above, according to the present invention, even if an excessive displacement occurs in the mass body due to an impact or the like, the contact between the Toruca electrodes can be avoided. Can be prevented. In addition, since the stopper can reduce the contact area when the mass body and the fixed electrode plate are in contact with each other, sticking due to friction between the surfaces can be prevented, and in these respects, reliability and durability are reduced. An excellent electrostatic torquer type accelerometer can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing one embodiment of the invention of claim 1;

FIG. 2 is an exploded perspective view of a mechanism in FIG.

FIG. 3 is a circuit diagram showing an example of a circuit configuration of a displacement detector in FIG. 1;

FIG. 4 is a cross-sectional view showing a state in which an excessive displacement has occurred in the mass body. FIG. 4A shows a case where the hinge is bent primary, and FIG. 4B shows a case where the hinge is bent secondary.

FIG. 5 is a perspective view for explaining another example of a structure for supporting a mass body by a hinge.

FIG. 6 is a sectional view showing one embodiment of the invention of claim 2;

FIG. 7 is a perspective view for explaining one embodiment of the invention of claim 3;

FIG. 8 is a perspective view for explaining another embodiment of the invention of claim 3;

FIG. 9 is a cross-sectional view illustrating an example of a conventional configuration of an electrostatic torquer accelerometer.

FIG. 10A is a cross-sectional view showing another example of the conventional configuration of the electrostatic torquer type accelerometer, and FIGS. 10B and 10C show the excessive displacement state of the mass body.

Claims (4)

[Claims] 1. Two fixed electrode plates are disposed opposite both plate surfaces of a plate-shaped mass body displaceably supported by a hinge, and a static electrode is provided between each of the mass bodies and the two fixed electrode plates. A capacitance detection electrode pair and a Toruca electrode pair are configured, and displacement of the mass body due to acceleration input is detected by a change in capacitance, and a voltage is applied to the Toruca electrode pair based on the detection output to detect the displacement. To a neutral position, wherein the stopper is located on an axis perpendicular to a plate surface passing through the center of gravity of the mass body, and stoppers are provided on both plate surfaces of the mass body, respectively. The stoppers are formed so as to protrude, the top surfaces of the stoppers serve as components of the capacitance detection electrode, and the Toruca electrode is formed on a plate surface of the mass body excluding the stopper formation portion. Electrostatic ToruCa accelerometer. 2. Two fixed electrode plates are arranged opposite both plate surfaces of a plate-shaped mass body displaceably supported by a hinge, and a static electrode is provided between each of the mass bodies and the two fixed electrode plates. A capacitance detection electrode pair and a Toruca electrode pair are configured, and displacement of the mass body due to acceleration input is detected by a change in capacitance, and a voltage is applied to the Toruca electrode pair based on the detection output to detect the displacement. An electrostatic torquer-type accelerometer having a structure for returning to a neutral position, wherein the accelerometer is positioned on an axis perpendicular to a plate surface passing through the center of gravity of the mass body and opposed to the mass body of the fixed electrode plates. Stoppers are respectively formed on the surfaces of the fixed electrodes, and the top surfaces of the stoppers serve as components of the capacitance detection electrodes. The Toruca electrodes are provided on the plate surfaces of the fixed electrode plates excluding the stopper formation portions. Electrostatic discharge Luke accelerometer. 3. Two fixed electrode plates are arranged opposite both plate surfaces of a plate-shaped mass body displaceably supported by a hinge, and a static electrode is provided between each of the mass bodies and the two fixed electrode plates. A capacitance detection electrode pair and a Toruca electrode pair are configured, and displacement of the mass body due to acceleration input is detected by a change in capacitance, and a voltage is applied to the Toruca electrode pair based on the detection output to detect the displacement. To a neutral position, comprising a center of gravity of the mass body, a plane perpendicular to a plate surface thereof, and parallel to a bending axis of the hinge. The stoppers are formed on lines intersecting the plate surface, respectively, and the top surfaces of the stoppers constitute the components of the capacitance detecting electrode, and the torquer electrode is formed on the plate surface of the mass body excluding the stopper forming portion. Is constituted. Electrostatic ToruCa accelerometer. 4. Two fixed electrode plates are disposed opposite both plate surfaces of a plate-shaped mass body displaceably supported by a hinge, and a static electrode is provided between each of the mass bodies and the two fixed electrode plates. A capacitance detection electrode pair and a Toruca electrode pair are configured, and displacement of the mass body due to acceleration input is detected by a change in capacitance, and a voltage is applied to the Toruca electrode pair based on the detection output to detect the displacement. To a neutral position, wherein the fixed electrode plates include a center of gravity of the mass body, a plane perpendicular to the plate surface, and parallel to the bending axis of the hinge. The stoppers are respectively formed on lines intersecting the plate surface facing the mass body, and the top surfaces of the stoppers serve as components of the capacitance detecting electrode. The stopper forming portions of the fixed electrode plates Except for the above Toruca electrode The electrostatic Toruca type accelerometer characterized by comprising.