JPH04258713A - Absolute tilt angle sensor - Google Patents

Abstract

PURPOSE:To obtain a small-sized absolute tilt angle sensor for detecting each tilt angle in the longitudinal and lateral directions by a single body. CONSTITUTION:A base 1, diaphragm 2, and a weight part 2 are formed by using the fine working technique for Si. The container-shaped weight part 2 is filled with the liquid 4 having high density such as mercury, and supported by the diaphragm 2. Piezo resistor elements 5a, 5b, 5c, and 5d are attached onto the upper surface of the diaphragm 2. When a sensor A tilts, the diaphragm 2 is distorted nonuniformly by the weight of the liquid 4, and the tilt angle in the longitudinal and lateral directions can be detected by detecting the distortion by the piezoresistor elements 5a, 5b, 5c, and 5d.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to absolute tilt angle sensors. Specifically, the present invention relates to an absolute inclination angle sensor for measuring the inclination of a vehicle body or the like with respect to the ground (or the direction of gravity).

0002

2. Description of the Related Art FIGS. 4(a) and 4(b) show a conventional mechanical absolute tilt angle sensor P. As shown in Figure 4(a),
A pendulum 53 is housed in a cavity 52 of a main body 51, and is rotatably supported by a shaft 54 at an eccentric position. For example, there is an instruction mark 55 on the center of gravity side of the pendulum 53.
is drawn, and a scale 56 is carved around the cavity 52.

However, when the main body 51 is horizontal as shown in FIG. 4(a), the indicator mark 5 of the pendulum 53
5 indicates the center of the scale 56, but even if the main body 51 is tilted as shown in FIG. 4(b), the pendulum 53 remains stationary. By reading the scale 56 indicated by the mark 55, the absolute inclination angle of the main body 51 can be determined.

However, the mechanical absolute tilt angle sensor is for visual observation and does not have a means for outputting a tilt angle detection signal. In addition, absolute tilt angle sensors with this structure can only detect tilt angles in one direction, such as front and back or left and right.In order to determine the tilt angle in two directions, front and back and left and right, two sensors are required by changing their orientation. There is a problem in that it is necessary to install several sensors, which increases the size of the structure.

FIGS. 5(a) and 5(b) show a capacitance type absolute tilt angle sensor Q. As shown in Figure 5(a), case 6
A liquid 65 is stored in a container 64 housed in the container 1 . Further, electrodes 62 are provided on the front and rear and left and right sides of the container 64, respectively.
63, .

[0006] However, there are two cases: when the absolute tilt angle sensor Q is horizontal as shown in FIG. 5(a), and when the absolute tilt angle sensor Q is tilted as shown in FIG. 5(b). , since the liquid distribution changes between the electrodes, the capacitance between the electrodes changes. Therefore, by detecting this change in interelectrode capacitance with the capacitance detection circuit 66, the tilt angle of the absolute tilt angle sensor Q can be determined.

However, even with an absolute tilt angle sensor having such a structure, the electrode area must be increased in order to improve the detection sensitivity. It was difficult to

FIG. 6 shows an optical absolute tilt angle sensor R. In this absolute tilt angle sensor R, a rotary plate 71 and a disk 72
are rotatably pivotally connected to each other, and a weight 74 is provided at an eccentric position of the disk 72. Therefore, even if the rotating plate 71 rotates, the disk 72 remains stationary due to the gravity of the weight 74. A scale section 73 in which transparent areas and opaque areas are alternately arranged at a constant pitch is provided around the entire edge of the disk 72, and an optical scale reader 75 such as a photointerrupter is installed at the edge of the rotary plate. is provided.

[0009] When the rotary plate 71 is tilted and the scale reader 75 moves along the scale portion 73, the scale reader 75 detects the movement pitch, so that the angle of inclination can be determined.

This optical absolute tilt angle sensor has substantially the same mechanical construction as the mechanical absolute tilt angle sensor shown in FIG. 4, and uses optical means for its output portion. For this reason, like a mechanical absolute tilt angle sensor, it can only detect the tilt angle in one direction;
If an attempt is made to detect the inclination angle of a direction, two sensors must be placed in different directions, resulting in an increase in size.

[0011]

[Problems to be Solved by the Invention] The present invention has been made in view of the drawbacks of the conventional examples described above, and its purpose is to detect inclination angles in two directions, front, back, left, and right using a single device. The object of the present invention is to provide a small-sized absolute tilt angle sensor that can perform the following functions.

0012

[Means for Solving the Problems] The absolute inclination angle sensor of the present invention has a weight portion held on a base via a diaphragm, and a strain detection element is attached to the diaphragm to detect strain at a plurality of locations. It is characterized by

[0013] In this case, the base, diaphragm and weight portion can be integrally formed of a microfabricated material such as silicon.

[0014] Furthermore, the weight portion may be formed in the shape of a container, and a high-density liquid may be placed in the container.

Furthermore, as the strain detection element, a piezoresistive element is preferable.

[0016]

[Operation] Since the weight part is pulled in the direction of gravity by gravity, when the absolute tilt angle sensor is tilted, the diaphragm between the base and the weight part is distorted non-uniformly around the weight part. If this distortion is detected by a distortion detection element,
The absolute tilt angle of the base relative to the direction of gravity can be determined.

Moreover, since the weight section is suspended from the base via the diaphragm, when the absolute tilt angle sensor is tilted, the diaphragm is distorted in the front, back, left and right directions due to the weight of the weight section. Therefore, by attaching the necessary number of strain detection elements to the diaphragm to detect strain in two directions, the tilt angles in the front, rear, left, and right directions can be detected using the output signals from the strain detection elements, and You can know the angle of inclination in two directions. Furthermore, since a single sensor can detect the tilt angle in two directions: front, rear, left, and right, miniaturization is possible.

In particular, if the base, diaphragm, and weight part are integrally formed from a microfabricated material such as silicon, they can be manufactured using microfabrication technology used in semiconductor manufacturing, etc. A tilt angle sensor can be manufactured.

Furthermore, if the container-shaped weight part is filled with a high-density liquid, the distortion of the diaphragm can be increased due to the weight of the liquid, and when the absolute tilt angle sensor is tilted, the liquid inside the weight part is Since the distortion of the diaphragm is amplified by shifting downward, signal sensitivity can be greatly improved.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 shows an absolute tilt angle sensor A according to an embodiment of the present invention.
A cross-sectional view is shown in FIG. 2, and a plan view thereof is shown in FIG. Reference numeral 1 denotes a base 1 made of a silicon substrate or the like, and a diaphragm 2 and a container-shaped weight part 3 are formed in the center of the base 1 using a microfabrication technique such as wet etching or dry etching. That is, the weight portion 3 is supported by a thin diaphragm 2 that can be slightly deformed. In this embodiment, as shown in FIG. 2, in order to increase the displacement of the weight part 3, the weight part 3 is
Openings 7 are formed at four locations between the base 1 and the base 1, and the diaphragm 2 is stretched between the base 1 and the weight part 3 in the middle of the openings 7. A high-density liquid 4 such as mercury is stored inside the weight part 3 in order to increase the distortion of the diaphragm 2. Furthermore, piezoresistive elements 5a, 5b, 5c, and 5d are attached or embedded on the upper surface of each diaphragm 2 as strain detection elements. Further, the upper portions of the diaphragm 2 and the weight portion 3 are covered by a cap 6.

When the absolute inclination angle sensor A is in a horizontal state as shown in FIG. join. At this time, since the force applied to each diaphragm 2 is the same, each piezoresistive element 5a, 5b,
There is no difference in the amount of distortion or deformation of each diaphragm 2 detected by 5c and 5d, and each piezoresistive element 5a, 5b, 5c
, 5d output the same electrical signal. On the other hand, when the absolute tilt angle sensor A is tilted, each diaphragm 2 is distorted unevenly due to the gravity applied to the liquid 4, and moreover, the liquid 4 in the weight part 3 is tilted downward. The distortion of each diaphragm 2 is amplified by the liquid 4 being shifted to one side. Piezoresistive elements 5a, 5b (or 5c,
5d), the inclination angle of the absolute inclination angle sensor A with respect to the direction of gravity can be measured with high precision.

Although the preferred embodiment has been described,
Other specific configurations are also possible as embodiments of the present invention. For example, in the above embodiment, an opening is provided between the diaphragms, but even without an opening, the distortion of the diaphragm can be increased by reducing the thickness of the diaphragm. Further, in the above embodiment, the weight part 3
Although a high-density liquid such as mercury is placed in the weight part, it is not possible to increase the weight of the weight part by forming a thick metal film on the inner and outer surfaces of the weight part, or by placing a solid weight such as metal in the weight part. good. Further, the weight may be increased by increasing the thickness of the weight portion itself. Furthermore, by providing piezoresistive elements only in two opposing diaphragm portions, it is possible to detect only the angle of inclination in one direction, such as front and back or left and right.

[0023] Possible uses of this absolute inclination angle sensor include, for example, the following uses. ■It is installed in a car and detects the inclination of the car using an absolute inclination angle sensor, allowing optimal suspension operation control, etc. ■Installed on large agricultural equipment, the absolute tilt angle sensor detects the inclination of large agricultural equipment during work, improving safety and work efficiency. Furthermore, in navigation systems that use communication with communication satellites, absolute inclination angle sensors are used to determine the inclination of a car or ship relative to the ground or sea surface, and control the inclination of the antenna so that it points accurately in the direction of the communication satellite.

[0024]

According to the present invention, inclination angles in two directions (front, rear, left, and right) can be detected with one sensor, and the absolute inclination angle sensor can be miniaturized. Furthermore, by manufacturing using a microfabricated material such as silicon, an extremely small absolute tilt angle sensor can be obtained. In addition, if a high-density liquid is placed inside the weight part, a sensitive absolute tilt angle sensor can be manufactured.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a plan view of the embodiment same as above.

FIG. 3(a) is an explanatory diagram of the operation of the above embodiment in a horizontal state, and FIG. 3(b) is an explanatory diagram of the operation in an inclined state.

FIG. 4 is an explanatory view of the operation of the conventional example, in which (a) is a sectional view in a horizontal state, and (b) is a sectional view in an inclined state.

FIG. 5 is an explanatory view of the operation of different conventional examples, in which (a) is a sectional view in a horizontal state, and (b) is a sectional view in an inclined state.

FIG. 6 is a front view showing the configuration of yet another conventional example.

[Explanation of symbols]

1 Base 2 Diaphragm 3 Weight section 4. Liquid

Claims (4)

[Claims] 1. An absolute tilt angle sensor, characterized in that a weight part is held on a base via a diaphragm, and a distortion detection element is attached to the diaphragm to detect distortions at a plurality of locations on the diaphragm. 2. The absolute tilt angle sensor according to claim 1, wherein the base, diaphragm, and weight portion are integrally formed of a microfabricated material such as silicon. 3. The absolute tilt angle sensor according to claim 2, wherein the weight part is formed into a container shape, and a high-density liquid is placed inside the weight part. 4. The absolute tilt angle sensor according to claim 1, wherein the strain detection element is a piezoresistive element.