JPH0727505A - Angle sensor - Google Patents

Abstract

PURPOSE:To provide an angle sensor capable of detecting an angle with high accuracy without requiring a complex structure in particular and excellent in durability. CONSTITUTION:Fixed electrodes 1, 2 are constituted of the first and second split electrodes 1a, 1b and 2a, 2b not electrically connected respectively. The first split electrodes 1a, 2a and the second split electrodes 1b, 2b constituting the fixed electrodes 1, 2 are electrically connected respectively. Weight and eccentricity of the center of gravity are applied to a mobile electrode 3 so that it can be kept at a fixed position by the gravitational force regardless of the rotational position of an angle sensor main body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contactless electrostatic capacitance type angle sensor for detecting a rotation angle or the like based on the amount of change in electrostatic capacitance.

[0002]

2. Description of the Related Art As a conventional angle sensor for detecting a tilt angle and a rotation angle, for example, an angle sensor for optically detecting an angle or an electric sensor using a potentiometer is used. An angle sensor for detecting an angle is known.

However, the optical angle sensor has a problem that the structure becomes complicated to obtain high accuracy and the manufacturing cost increases, and that the resolution becomes low when the digital type is used. is there.

On the other hand, since the angle sensor using the potentiometer has contact points, there is a problem that the contact is worn by sliding and the measurement accuracy is lowered, and that the life is short.

Further, as another conventional angle sensor,
For example, as in the angle detection device disclosed in Japanese Patent Laid-Open No. 61-80002, it is provided with a center electrode arranged at the center of the cylinder and a detection electrode arranged on the inner surface of the cylinder in two equal parts. As two kinds of dielectrics having different dielectric constants, there is an angle sensor in which a gas and a liquid are enclosed in a cylinder.

However, in an angle sensor (angle detection device) using such a liquid, when vibration is applied to the liquid, the liquid surface becomes wavy, which makes it difficult to measure the angle, or the measurement accuracy decreases. There is a problem of doing. In addition, there is a problem that a measurement error occurs due to the hysteresis caused by the viscosity of the liquid.

The present invention solves the above-mentioned problems, and an angle sensor which can detect an angle with high accuracy without requiring a particularly complicated structure and is excellent in durability. The purpose is to provide.

[0008]

In order to achieve the above object, the angle sensor of the present invention is inserted between the fixed electrodes arranged so as to face each other and the fixed electrodes without contacting each other. A non-contact capacitance type which comprises a movable electrode rotatably supported by a shaft, and detects an angle by measuring a variation amount of a capacitance formed between the fixed electrode and the movable electrode. In the angle sensor according to the first aspect, the fixed electrode is composed of first and second divided electrodes that are not electrically connected to each other, and the fixed electrode is composed of a first electrode.
The divided electrodes and the second divided electrodes forming the fixed electrodes are electrically connected to each other, and the movable electrodes are kept at a constant position by gravity regardless of the rotational position of the angle sensor body. It is characterized by imparting a certain weight and a bias of the center of gravity.

Further, the position of the movable electrode in the reference state has a capacitance that is formed when a predetermined inclination is generated from the reference state, and the capacitance is generated when the inclination is positive or negative. It is characterized in that it is set at a position where it has a size approximately at the center of the range in which it changes substantially linearly.

Further, the movable electrode is characterized in that its planar shape is formed in a substantially semicircular shape.

Further, the movable electrode is composed of first and second divided electrodes which are not electrically connected to each other, and the two divided electrodes are different from each other in at least one of weight and shape. It is characterized by

Further, a fixed electrode position adjusting mechanism for adjusting the distance between the fixed electrode and the movable electrode is provided.

Further, the present invention is characterized by having a stacking mechanism for stacking a plurality of sets of the fixed electrode and the movable electrode.

[0014]

The angle sensor of the present invention is a non-contact type and has no wear portion (contact portion), so that durability and electrical characteristics do not depend on the life or contact state of the contact portion, and durability and reliability are ensured. It becomes possible to improve.

Further, since the movable electrode is kept at a fixed position regardless of the rotational position of the angle sensor body, the positional relationship between the movable electrode and the fixed electrode continuously changes depending on the angle. Therefore, the resolution is improved, and it becomes possible to detect a minute change in angle with high accuracy.

The movable electrodes are formed in a substantially semicircular shape, or the first and second electrodes are not electrically connected to each other.
It is possible to reliably maintain the movable electrode at a constant position regardless of the rotational position of the angle sensor body by configuring the movable electrode by at least one of the weight and the shape of the two divided electrodes. It will be possible.

Further, by forming the movable electrode from the two divided electrodes, it is possible to increase the amount of change in capacitance per angle and further improve the sensitivity.

Further, the position of the movable electrode in the reference state (for example, a horizontal state without inclination) is such that the magnitude of the capacitance formed when a predetermined inclination occurs from the reference state is positive or negative. Even if it occurs, by setting it to a position that is approximately the center of the range in which the capacitance changes substantially linearly, the angle is ensured regardless of whether the tilt direction is positive or negative. Therefore, it is possible to detect whether the inclination direction is positive or negative, as well as being able to accurately detect.

Further, by providing the fixed electrode position adjusting mechanism for adjusting the distance between the fixed electrode and the movable electrode, it becomes possible to easily finely adjust the distance between the fixed electrode and the movable electrode, and the formed static electrode can be easily adjusted. It is possible to improve the accuracy of the capacitance and prevent the occurrence of problems such as breakdown voltage abnormality.

Further, by providing a stacking mechanism for stacking a plurality of sets of fixed electrodes and movable electrodes, it is possible to increase the number of fixed electrodes and movable electrodes as needed, and it is possible to obtain a desired capacitance. .

[0021]

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

[Embodiment 1] FIG. 1 is an exploded perspective view showing an angle sensor according to an embodiment of the present invention. 2 is a view showing the assembled angle sensor,
(A) is the front sectional view, and (b) is a side view.

In the angle sensor A of this embodiment, as shown in FIGS. 1 and 2, it is movable between the first fixed electrode 1 and the second fixed electrode 2 which are arranged so as to face each other. Electrode 3
Is inserted without contact. The movable electrode 3 is rotatably held by the movable electrode fixing member 6b attached to the upper end of the shaft body 6a without contacting the fixed electrodes 1 and 2. The movable electrode fixing member 6b is made of a synthetic resin such as PPS resin or LCP resin, or an insulator such as ceramic,
The shaft 7 is configured with the metal shaft body 6a. However, the material forming the shaft body 6a is not limited to metal, but may be composed of synthetic resin such as PPS resin or LCP resin, or insulating material such as ceramic.

The first fixed electrode 1 is composed of first and second divided electrodes 1a and 1b having a substantially semicircular shape which is not electrically connected to each other and has a protrusion 11 in which a hole 11 through which the mounting screw 8 is inserted is formed. The second fixed electrode 2 is also composed of first and second divided electrodes 2a and 2b.

Further, in the angle sensor A of this embodiment, the movable electrode 3 is formed in a substantially semicircular shape and has a size enough to have a predetermined weight. This overcomes the static frictional force between the shaft 7 and the bearing 5 rotatably supporting the shaft 7 and the weight of the shaft 7 so that the movable electrode 3 is kept at a constant position regardless of the rotational position of the shaft 7. The weight and the center of gravity are biased. In this embodiment, as the bearing 5 supporting the shaft 7, a rolling bearing having a small torque is used.

The first and second fixed electrodes 1 and 2 are
As the material for forming the movable electrode 3, various conductive materials such as metal can be used. It is also possible to form electrodes by applying metal plating or the like to the surface of an insulating material such as resin to give conductivity.

Further, in the angle sensor A, the bearing 5 rotatably supporting the shaft body 6a constituting the shaft 7 is fitted into the hole 4a formed in the base (fixed electrode mounting member) 4 made of an insulating material. Has been.

The bearing 5 eliminates the play in the thrust direction and prevents the fluctuation of the formed electrostatic capacitance, so that the bush 9 inserted into the hole 4a from the lower surface side of the base 4 and the movable electrode fixing member 6b. It is held by.

In the movable electrode 3, the concave portion 3d formed in the center of the side 3c having no curvature is engaged (fitted) with the groove 6c formed around the movable electrode fixing member 6b. , Is fixed to the movable electrode fixing member 6b.

Then, the first and second fixed electrodes 1, 2
Inserts a mounting screw 8 made of a material having the same conductivity as the fixed electrodes 1 and 2 through the hole 11 into the screw hole 1 of the base 4.
It is attached to the base 4 by being screwed into 0, and a notch 14 for passing the shaft 7 is formed in the center thereof. A washer-shaped spacer 12 is provided between the first and second fixed electrodes 1 and 2 to secure a predetermined distance therebetween, and the base 4 and the second fixed electrode 12 are provided. A cylindrical base spacer 13 is provided between the fixed electrodes (lower fixed electrode) 2 for determining the positional relationship between the movable electrode 3 and the fixed electrodes 1, 2. Of the spacer 12 and the base spacer 13,
At least the spacer 12 is made of a conductive material, and the mounting screw 8 penetrates the spacer 12 and the base spacer 13 and is screwed into the screw hole 10 of the base 4.

The spacer 12 and the base spacer 1
3 or the movable electrode fixing member 6b and the groove 6
By adjusting the arrangement position of c, etc., the fixed electrode 1,
It is possible to arbitrarily adjust the positional relationship between 2 and the movable electrode 3.

In this way, the fixed electrodes 1 and 2 and the movable electrode 3 are
Mechanism to adjust the positional relationship with (fixed electrode position adjustment mechanism)
By providing the above, it is possible to improve the accuracy of the capacitance and prevent problems such as abnormal breakdown voltage from occurring.

The mounting screws 8 and the spacers 12 electrically connect the first divided electrodes 1a and 2a and the second divided electrodes 1b and 2b which form the first and second fixed electrodes 1 and 2, respectively. The first and second divided electrodes (1a, 2a), (1b, 2b) are electrically connected to output terminals (not shown).

Then, each of the above components is housed in a case 21 (FIG. 2A) made of a conductive material and configured to be groundable to prevent the influence of stray capacitance. Example angle sensor A (Fig. 2
(A) and (b) are formed.

Next, the positional relationship between the movable electrode 3 and the first and second fixed electrodes 1 and 2 and the electrostatic capacity relationship in the angle sensor A of this embodiment will be described with reference to FIG. . As shown in FIG. 3, a horizontal piece 3c of the movable electrode 3 and
Gap portions 1c of the semicircular divided electrodes 1a, 1b and 2a, 2b constituting the first or second fixed electrodes 1, 2,
When the angle (rotation angle) θ with 2c (FIGS. 1 and 2 (b)) is 0 ° and 180 °, the formed capacitance is minimum (C
_MIN ) and the maximum (C _MAX ) at 90 ° and 270 °.

Further, in the angle sensor A of this embodiment, the positional relationship between the movable electrode 3 and the fixed electrodes 1 and 2 in the reference state is an electrostatic charge formed when a predetermined inclination is generated from the reference state. The magnitude of the capacitance is approximately the center value of the range in which the capacitance changes substantially linearly (i.e., the range of C _{MIN to} C _MAX ) regardless of whether positive or negative inclination occurs.
That is, the rotation angle θ has a value represented by a point P in FIG. However, in the case where the tilt to be measured is limited to the use in which it is biased to either positive or negative, the setting position of the movable electrode 3 is set to the electrostatic capacitance as in the case of the above-mentioned embodiment. It is not necessary to limit to the vicinity of the median of the linear change range, and it is possible to set it to a preferable position in accordance with the deviation direction.

Next, the operation of the angle sensor A configured as described above will be described. In the angle sensor A,
The movable electrode 3 is formed in a semicircular shape having a predetermined weight so as to have a static frictional force between the shaft 7 and the bearing 5 and a weight and a center of gravity that are sufficient to overcome the weight of the shaft 7 and the like. It is attached to (possible movable electrode fixing member 6b constituting) the possible shaft 7. Therefore,
When the angle sensor A is arranged and used at a predetermined position, as shown in FIG. 2B, the body of the angle sensor A is rotated (tilted) from the reference state in the direction indicated by the arrow X or Y.
In this case, the movable electrode 3 tries to keep the center of gravity low with respect to the inclination of the body of the angle sensor A. As a result, the movable electrode 3 is
The position shown in (b) is maintained, the positional relationship between the first and second fixed electrodes 1 and 2 changes, and the facing area between the movable electrode 3 and the fixed electrodes 1 and 2 changes. Then, it is possible to detect the tilt angle by measuring the amount of change in the capacitance between the movable electrode 3 and the fixed electrodes 1 and 2 caused thereby.

Further, in the angle sensor A, the magnitude of the electrostatic capacitance formed when a predetermined inclination occurs is changed so as to be substantially linear regardless of whether the inclination is positive or negative. Since the positional relationship between the movable electrode 3 and the fixed electrodes 1 and 2 in the reference state is set, the tilt angle can be detected reliably and accurately regardless of whether the tilt direction is positive or negative. it can.

In the above embodiment, the shaft body 6a is
The case where the shaft 7 is configured by connecting the movable electrode fixing member 6b to the shaft 7 has been described.
It is also possible to form the shaft 7 by integrally molding a and the movable electrode fixing member 6b using an insulating material such as synthetic resin such as PPS or LCP resin or ceramic. It is also possible to integrally mold the movable electrode 3 and the movable electrode fixing member 6b by a method such as insert molding.

It is also possible to impart conductivity by integrally forming the movable electrode, the movable electrode fixing member, and the shaft body using an insulating material, and subjecting only the electrode portion to a surface treatment such as plating.

Further, it is possible to integrate the spacer 12 and the base spacer 13 of the above embodiment with the fixed electrodes 1 and 2.

Furthermore, in the above embodiment, the angle sensor A in which only one combination (mechanism) consisting of two fixed electrodes and movable electrodes inserted between the fixed electrodes is formed has been described. In the angle sensor, a stacking mechanism for stacking the fixed electrode and the movable electrode is provided so as to form a plurality of combinations of the fixed electrode and the movable electrode, and a plurality of sets of the fixed electrode and the movable electrode are stacked to obtain C _MAX. It is possible to further increase the capacitance difference ΔC between C _MIN and C _MIN . As the stacking mechanism, a plurality of grooves are formed in the shaft (or a movable electrode fixing member forming the shaft) and a plurality of fixed electrodes are arranged so that a plurality of movable electrodes can be inserted and fixed. In order to be able to do so, it is possible to have various configurations, such as forming the mounting screws for the shaft and the fixed electrode to be long, and disposing a plurality of spacers, and there is no particular restriction on the specific configuration.

Further, in the above embodiment, the shaft 7 is constructed so as not to project from the case 21 (FIG. 2A), but it is constructed so as to project from the case 21 so that the shaft 7 can be operated from the outside. You may do it. Further, the shaft 7 can be configured so that both ends thereof are supported by bearings.

In the above embodiment, the semicircular movable electrode 3 is used.
However, the shape of the movable electrode 3 does not necessarily have to be a perfect semi-circular shape, and as long as it does not adversely affect the change in the capacitance due to the change in the angle, the movable electrode 3 shown in FIG. , (B), the central angle is 18
The shape (substantially semicircular) can be larger than 0 ° or smaller than 180 °.

Further, in the above embodiment, the central angle of each of the first divided electrode forming the fixed electrode and the second divided electrode forming the fixed electrode is 180 °, and the total of the central angles is 360 °. However, the present invention is not limited to this. For example, the first and second
It is possible to make different changes in the central angles of the divided electrodes, and to make various changes, for example, to make the total of the central angles less than 360 ° C. Further, the combination with the central angle of the movable electrode can be various combinations.

[Embodiment 2] FIGS. 5 and 6 are views showing the main parts (structures of a fixed electrode and a movable electrode) of an angle sensor according to another embodiment of the present invention.

In the embodiment of FIG. 5, the movable electrode 3 is
Made of conductive material, almost semi-circular, planar shape (dimensions)
Are the same, but the two divided electrodes 3a, 3 having different thicknesses
b, and the weights of the two divided electrodes 3a and 3b are different from each other.

Further, in the embodiment of FIG. 6, the movable electrode 3 is made of a conductive material, has a substantially semicircular shape, and has the same thickness, but two divided electrodes 3 having different planar shapes (dimensions).
a, 3b, and two divided electrodes 3a, 3b
The weights of b are different from each other.

In the angle sensor of the embodiment shown in FIGS. 5 and 6, the movable electrode 3 is kept at a constant position regardless of the rotational position of the angle sensor body, and the angle sensor A of the above embodiment is used.
The same effect as can be obtained, and the movable electrode 3
Is composed of two divided electrodes 3a and 3b,
The amount of change in capacitance per angle becomes large, and the sensitivity can be further improved.

The method of making the weights of the pair of divided electrodes constituting the movable electrode different (giving a weight difference) is not limited to the method of the above-mentioned embodiment, but the specific gravity can be changed by making the materials different. It is possible to use various methods such as a method of causing a weight difference due to the difference or a method of attaching a weight to one of the divided electrodes.

The present invention is not limited to the above embodiments in other respects, and various applications and modifications can be made within the scope of the invention.

[0052]

As described above, in the angle sensor of the present invention, the fixed electrode is composed of the first and second divided electrodes which are not electrically connected to each other, and the first fixed electrode is constituted. A weight such that the divided electrode and the second divided electrode forming each fixed electrode are electrically connected to each other, and the movable electrode is kept at a constant position by gravity regardless of the rotational position of the angle sensor body. Since the center of gravity is biased, the positional relationship between the movable electrode and the fixed electrode continuously changes depending on the angle. Therefore, the resolution is improved, and it becomes possible to accurately detect a minute change in angle.

Further, since the angle sensor of the present invention is a non-contact type and a contact portion (wear portion) is not required, reliability and durability can be improved. Further, since it is a capacitance-type angle sensor that uses an air layer, it is possible to obtain stable characteristics that are unlikely to be affected by the ambient temperature. Furthermore, since the mechanism for detecting the angle and the mechanism for generating the capacitance change are one mechanism, the sensitivity and reproducibility can be improved. Moreover, the structure is simple and the productivity is excellent.

Furthermore, the movable electrode may be a substantially semicircular electrode plate, or may be composed of first and second divided electrodes that are not electrically connected to each other, and at least one of the weight and the shape of the two divided electrodes may be formed. By making them different, the movable electrode can be moved regardless of the rotation position of the angle sensor body.
It is possible to reliably maintain a fixed position.

Further, by forming the movable electrode from two divided electrodes, it is possible to increase the amount of change in capacitance per angle and further improve the sensitivity.

Further, the position of the movable electrode in the reference state (for example, a horizontal state without inclination) is such that the magnitude of the capacitance formed when a predetermined inclination occurs from the reference state is positive or negative. Even if it occurs, by setting it to a position that is approximately the center of the range in which the capacitance changes substantially linearly, the angle is ensured regardless of whether the tilt direction is positive or negative. It becomes possible to detect with high accuracy, and it is possible to detect whether the direction of inclination is positive or negative.

Further, by providing the fixed electrode position adjusting mechanism for adjusting the distance between the fixed electrode and the movable electrode, it becomes possible to finely adjust the distance between the fixed electrode and the movable electrode, and the accuracy of the capacitance formed. It is possible to easily increase the resistance, and it is possible to prevent the occurrence of problems such as breakdown voltage abnormality.

Further, by providing a stacking mechanism for stacking a plurality of sets of fixed electrodes and movable electrodes, it is possible to increase the number of fixed electrodes and movable electrodes as needed, and it is possible to obtain a desired capacitance. Like Therefore, the degree of freedom in design can be improved. Further, by vertically stacking a plurality of sets of fixed electrodes and movable electrodes, it is possible to increase the capacitance by slightly increasing the dimension in the thickness direction, and it is possible to reduce the size of the angle sensor as a whole. .

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an angle sensor according to an embodiment of the present invention.

2A and 2B are views showing an angle sensor according to an embodiment of the present invention, in which FIG. 2A is a front sectional view and FIG. 2B is a side view.

FIG. 3 is a diagram showing a relationship between a rotation angle and a magnitude of a capacitance formed in the angle sensor according to the embodiment of the present invention.

FIG. 4 is a diagram showing a modified example of a substantially semicircular movable electrode in the angle sensor according to the embodiment of the present invention, FIG.
FIG. 3B is a diagram showing a movable electrode having a central angle larger than 180 ° and FIG.

5A and 5B are views showing a main part of an angle sensor according to still another embodiment of the present invention, FIG. 5A being a perspective view and FIG. 5B being a sectional view.

6A and 6B are views showing a main part of an angle sensor according to still another embodiment of the present invention, in which FIG. 6A is a perspective view and FIG. 6B is a sectional view.

[Explanation of symbols]

 1, 2 First and second fixed electrodes 1a, 2a First divided electrodes 1b, 2b forming fixed electrodes Second divided electrodes 1c, 2c forming fixed electrodes Gap portion of fixed electrode 3 Movable electrode 3a Movable 1st division | segmentation electrode which comprises an electrode 3b 2nd division | segmentation electrode which comprises a movable electrode 4 Base 5 Bearing (bearing) 6a Shaft main body 6b Movable electrode fixing member 6c Groove 7 Shaft 8 Mounting screw 9 Bushing 10 Screw hole 11 Hole 12 Spacer 13 Base spacer 14 Notch 21 Case A Angle sensor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hirotake Okunishi 26-10 Tenjin, Nagaokakyo-shi, Kyoto Murata Manufacturing Co., Ltd. Murata Manufacturing

Claims (6)

[Claims] 1. A fixed electrode disposed so as to face each other, and a movable electrode inserted between the fixed electrodes without contacting each other and rotatably supported by a shaft,
In a non-contact capacitance type angle sensor that detects an angle by measuring the amount of change in capacitance formed between the fixed electrode and the movable electrode, the fixed electrodes are electrically connected to each other. The first divided electrode which is composed of the first and second divided electrodes which is not formed, and which is electrically connected to the first divided electrode which forms each fixed electrode and the second divided electrode which forms each fixed electrode, respectively. An angle sensor characterized in that the weight and the center of gravity are biased so that the electrodes are kept at a constant position by gravity regardless of the rotational position of the angle sensor body. 2. The position of the movable electrode in the reference state is the capacitance formed when a predetermined inclination is generated from the reference state, and the electrostatic capacitance is obtained regardless of whether the inclination is positive or negative. 2. The angle sensor according to claim 1, wherein the angle sensor is set at a position that has a size approximately at the center of a range in which the value changes substantially linearly. 3. The angle sensor according to claim 1, wherein the movable electrode has a substantially semicircular planar shape. 4. The movable electrode is composed of first and second divided electrodes which are not electrically connected to each other, and the two divided electrodes are different from each other in at least one of weight and shape. Claim 1 characterized by the above.
The described angle sensor. 5. The angle sensor according to claim 1, further comprising a fixed electrode position adjusting mechanism for adjusting a distance between the fixed electrode and the movable electrode. 6. The angle sensor according to claim 1, further comprising a stacking mechanism for stacking a plurality of sets of the fixed electrode and the movable electrode.