JPS5953485B2 - Tilt sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inclination sensor that capacitively detects an inclination angle with respect to the direction of gravity of the earth and obtains an output voltage proportional to the inclination angle.

Conventionally, this type of tilt sensor has a structure in which the rotating shaft of a precision potentiometer is driven by the rotational force of a weight, or a structure that combines a meter mechanism and an electronic circuit mainly consisting of a photocoupler, but the temperature characteristics In order to improve stability and resolution, the mechanism is complicated and precision parts such as expensive precision potentiometers must be used, which means that it cannot be constructed in a compact and inexpensive manner.

In addition, with a shaft encoder that detects the rotation angle by converting the electrostatic capacitance change between the quantitative plate and the rotary plate into a periodic code output, it is detected that when an attempt is made to detect the absolute value of the rotation angle, The drawback is that it requires a complicated configuration of the unit and signal processing device, making it impossible to apply it as an inexpensive tilt sensor.

In order to eliminate these drawbacks, the present invention uses a capacitive detection method that can be configured with a simple structure to construct a small and inexpensive tilt sensor that is stable and highly sensitive to changes in environmental conditions such as temperature and humidity. It was made possible.

The drawings will be explained in detail below.

FIG. 1 is a longitudinal cross-sectional view showing one embodiment of the present invention, and FIG. 2 is a view showing opposing surfaces of the rotating body and the fixed electrode substrate.

1 is a rotating body having conductive members 1a and 1b on both sides and a weight 2 inside, and 1C is the center of rotation.

3 is a shaft, and 4 is a housing having bearings 4a and 4b.

The rotating body 1 is rotatably supported by a shaft 3 in bearings 4a and 4b.

Further, the conductive members 1a and lb of the rotating body 1 have a fan-shaped shape with respect to the center of rotation 1C, as shown by the vertical line in FIG. A weight 2 is provided to allow this.

5 and 6 are fixed electrode substrates, and fixed electrodes 5a, 5b, 5C, 6a, and
6b and 6C are conductive members 1a as shown in FIG.
, lb, and is divided concentrically into a fan shape and is symmetrical, and is parallel to the conductive members 1a and lb.

5a', 5b', 5c', 6a', 6b'
, 6c' is a connection terminal, and fixed electrodes 5a, 6a, 5b
and 6b, and 5C and 60 are electrically connected to each other.

The inside of the casing 4 is filled with a damping oil 7 such as silicone oil, which acts as a damper to suppress vibrations of the rotating body 1.

8 is a shield cover made of a conductive material, which prevents the influence of stray capacitance caused by the proximity of conductors or dielectrics, and external noise.

9 is a cover, and if this is made of a conductive material, it goes without saying that the shield cover 8 will be unnecessary.

Next, the operation will be explained.

Fixed electrodes 5a, 5b, 5C, 6a, 6b, 6C
The relative positional relationship between the conductive members 1a and lb is shown in FIGS. 1 and 2.
When the bottom surface 4C of the casing is in the horizontal position as shown in FIG. 31, when it is tilted by an angle θ1 as shown in FIG. As the center of gravity moves toward the direction of Earth's gravity, it rotates by θ1,
Conductive members 1a, lb and fixed electrodes 5a, 5a and 5b,
The opposing area with 6b increases by the area corresponding to the angle θ1 on one side, and decreases on the other side by the area corresponding to the angle θ1.

However, the facing areas of the fixed electrodes 5c, 5c and the conductive members 1a, lb remain unchanged.

Capacitance CI configured between fixed electrodes 5a, 6a and fixed electrodes 5c, 6C via conductive members 1a, lb, and between fixed electrodes 5b, 6b and fixed electrodes 5c, 5C via conductive members 1a, lb. The electrostatic capacitance C2 constituted by the fixed electrode changes in proportion to the change in the facing area of the fixed electrode and the conductive member, and the change in the facing area changes in proportion to the inclination angle.

In particular, according to the present invention, since the fixing plates on both sides are symmetrical and connected to each other, the capacitance is reduced even if the rotating body 1 moves in the axial direction due to the inclination with respect to the axial direction of the rotating body 1. Since there is no change in CI and C2, it is possible to accurately detect inclinations only in a predetermined direction.

FIG. 3 1 shows the relative positional relationship with the fixed electrode when the conductive members 1a and 1b are in their normal positions, and FIG.
, 5a increases by the angle θ1, and the area facing the fixed electrodes 5b and 6b decreases by the angle θ1.

In this way, capacitances C1 and C2 are obtained which increase and decrease in opposite directions in proportion to the inclination angle.

Note that the shapes of the conductive member and the fixed electrode may not be completely circular but may be like the electrodes 10a, 10b, 10C (7) in FIG. 4, as long as the capacitances CI and C2 are proportional to the inclination angle.

The conversion from capacitance change to DC voltage change is based on the circuit diagram shown in FIG.

Capacitance, voltage conversion circuit CV1゜CV2, capacitance CI, C
By converting the output voltage into a DC voltage proportional to 2 and differentially amplifying the output voltage using a differential amplifier DA, it is possible to obtain a DC voltage output proportional to the tilt angle with high sensitivity.

As explained above, the structure is such that two capacitance changes that increase and decrease in opposite directions in proportion to the inclination angle are detected, converted to DC voltage changes, and then differentially amplified to obtain the output voltage. , even if the capacitance changes due to changes in environmental conditions such as temperature and humidity or due to the effects of stray capacitance, they can cancel each other out, and only the changes in capacitance are amplified, making it a highly sensitive tilt sensor. can be configured.

Another advantage is that the rotating body can be easily constructed from an integral member made of a conductive material.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of the present invention, FIG. 2 is a view showing the opposing surfaces of the rotating body and the fixed electrode substrate, and FIG. 3 is a diagram showing the relative positional relationship between the rotating body and the fixed electrode. Figure, 4th
The figure shows the shapes of the fixed electrode and rotating body of another embodiment, and FIG. 5 is a circuit diagram for obtaining a DC voltage output proportional to the tilt angle. 1... Rotating body, 2... Weight, 3...
...Shaft, 4...Housing, 4a, 4b.
... Bearing part, 5, 6 ... Fixed electrode board,
5a, 5b, 5C, 6a, 6b, 6C
, 10a, 10b, 10C---fixed electrode, 7---braking oil, 8---shield cover, 9---cover.

Claims (1)

[Scope of Claims] 1. In a capacitive tilt sensor in which fixed electrode plates are disposed in parallel to each other on both sides of a rotatably supported plate-shaped body in the vicinity of the plate-shaped rotating body, one of both sides of the rotating body is The rotating body is configured such that the center of gravity of the rotating body is unevenly distributed from the center of rotation, and the fixed electrode plates on both sides are each provided with a conductive member and a conductive member of the rotating body with respect to the rotation angle of the rotating body. The first and second fixed electrodes, whose opposing areas increase on one side and decrease on the other, and the third fixed electrode, whose opposing area does not change, are symmetrically separated on substantially the same plane, and the electrodes are mutually connected to each other. A capacitance C1 is configured between the first and third fixed electrodes via a conductive member of a rotating body, and a capacitance C1 is configured between the second and third fixed electrodes via a conductive member of a rotating body. A tilt sensor characterized in that the capacitance C2 is converted into a capacitance voltage and differentially amplified to obtain an output proportional to the tilt angle with respect to the direction of gravity. 2. The tilt sensor according to claim 1, wherein the rotating body is integrally formed of a conductive member.