JP7281124B2 - ANGLE SENSOR, MOUNTING DEVICE, AND MEASUREMENT METHOD - Google Patents

Description

The present invention relates to an angle sensor that detects the rotation angle of a rotating body. The present invention also relates to a mounting device provided with such an angle sensor. The present invention also relates to a rotation angle measuring method using such an angle sensor.

An angle sensor that detects the rotation angle of a rotating body is widely used. For example, Patent Document 1 discloses an angle sensor that detects the rotation angle of a rotating body based on a change in capacitance between a fixed electrode and a movable electrode that face each other across a plane perpendicular to the rotation axis. ing. In the angle sensor described in Patent Document 1, a semicircular planar electrode is used as the fixed electrode, and a quadrant planar electrode is used as the movable electrode.

JP-A-7-27506

However, the angle sensor described in Patent Literature 1 is not suitable for detecting minute rotation angles such as detection of rotation angles of mirrors forming an optical system. This is because the angle sensor described in Patent Document 1 adopts an electrode arrangement in which the common portion of the orthogonal projection of the fixed electrode and the orthogonal projection of the movable electrode is close to the rotation axis on the plane orthogonal to the rotation axis, and the detection accuracy is This is because (resolution) is low.

Each aspect of the present invention has been made in view of the above problems. An object of one aspect of the present invention is to realize an angle sensor that detects a rotation angle of a rotating body with higher detection accuracy than conventional angle sensors. Another aspect of the present invention aims at realizing a measuring method for measuring the rotation angle of a rotating body with higher measurement accuracy than the conventional one. Another aspect of the present invention is to realize a mounting device for mounting an article, which can accurately detect the orientation of the article.

An angle sensor according to aspect 1 of the present invention is an angle sensor for detecting a rotation angle θ of a rotating body whose rotation axis is fixed to a reference body, comprising: a reference plane electrode fixed to the reference body; and a rotating plane electrode fixed to the rotating shaft, the rotating plane electrode facing the reference plane electrode across a plane orthogonal to the rotation axis. Further, in the angle sensor according to aspect 1 of the present invention, the common portion between the orthogonal projection of the reference plane electrode onto the plane and the orthogonal projection of the rotating plane electrode onto the plane is shifted from the rotation axis to the common portion. d1 is the distance to the point closest to the rotation axis, d2 is the distance from the rotation axis to the farthest point from the rotation axis in the common portion, and d2−d1≦d1 when θ is 0° A configuration is adopted that satisfies

According to the above configuration, the distance from the rotating shaft to the common portion is longer than that of the conventional angle sensor. Therefore, according to the above configuration, it is possible to realize an angle sensor with higher detection accuracy than the conventional one.

In the angle sensor according to aspect 2 of the present invention, in addition to the configuration of the angle sensor according to aspect 1, the reference plane electrodes are arranged side by side on a plane facing one surface of the rotation plane electrodes. A configuration is employed that includes a first planar electrode and a second planar electrode.

According to the above configuration, it is possible to further improve the detection accuracy of the rotation angle.

In the angle sensor according to aspect 3 of the present invention, in addition to the configuration of the angle sensor according to aspect 2, the reference plane electrodes are arranged side by side on a plane facing the other surface of the rotation plane electrodes. further comprising a third planar electrode and a fourth planar electrode, wherein the third planar electrode is connected in parallel with the first planar electrode and the fourth planar electrode is connected in parallel with the second planar electrode; Connected, configured.

According to the above configuration, it is possible to suppress deterioration in detection accuracy of the rotation angle that may occur when the plane-of-rotation electrode is tilted or when the plane-of-rotation electrode is translated.

A mounting device according to aspect 4 of the present invention includes a frame, a first gimbal having a rotation axis fixed to the frame, and a second gimbal having a rotation axis fixed to the first gimbal, and mounts an article. and the angle sensor according to any one of aspects 1 to 3, wherein the reference plane electrode is fixed to the frame, and the rotating plane electrode is fixed to the first gimbal. a sensor, and a second angle sensor according to any one of aspects 1 to 3, wherein the reference plane electrode is fixed to the first gimbal and the rotation plane electrode is fixed to the second gimbal; , is equipped with

According to the above configuration, it is possible to realize a mounting device that can accurately detect the orientation of an article.

In addition to the configuration of the mounting device according to aspect 4, the mounting device according to aspect 5 of the present invention employs a configuration in which the article is a mirror.

According to the above configuration, it is possible to realize a mounting device that can accurately detect the orientation of the mirror.

A measuring method according to aspect 6 of the present invention is a measuring method for measuring the rotation angle θ of the rotating body using the angle sensor according to aspect 1, comprising the step of inputting an alternating voltage to the rotating plane electrode; determining the rotation angle θ based on a DC voltage proportional to the amplitude of the AC current induced in the reference plane electrodes.

According to the above configuration, it is possible to realize a measurement method capable of accurately measuring the rotation angle θ of the rotating body.

A measurement method according to aspect 7 of the present invention is a measurement method for measuring the rotation angle θ of the rotating body using the angle sensor according to aspect 2, comprising the step of inputting an AC voltage to the rotation plane electrode; rotation angle θ based on the difference between a first DC voltage proportional to the amplitude of the AC current induced in the first planar electrode and a second DC voltage proportional to the amplitude of the AC current induced in the second planar electrode; and identifying.

According to the above configuration, it is possible to realize a measuring method capable of measuring the rotation angle θ of the rotating body with higher accuracy.

A measuring method according to aspect 8 of the present invention is a measuring method for measuring the rotation angle θ of the rotating body using the angle sensor according to aspect 3, comprising the step of inputting an alternating voltage to the rotating plane electrode; A first DC voltage proportional to the amplitude of the sum of the alternating currents induced in the first planar electrode and the third planar electrode and the sum of the alternating currents induced in the second planar electrode and the fourth planar electrode determining the rotation angle θ based on the difference from a second DC voltage proportional to the amplitude of .

According to the above configuration, it is possible to realize a measurement method capable of accurately measuring the rotation angle θ of the rotating body even when the rotating plane electrode is tilted.

A measurement method according to aspect 9 of the present invention, in addition to the configuration of the measurement method according to aspect 7 or 8, is such that the sum of the first DC voltage and the second DC voltage is constant, the rotating plane Arrangements are employed which further include the step of controlling the amplitude of the alternating voltage applied to the electrodes.

According to the above configuration, the difference between the first DC voltage and the second DC voltage corresponds one-to-one with the rotation angle θ of the rotor. Therefore, it is possible to accurately measure the rotation angle θ of the rotating body based on the difference between the first DC voltage and the second DC voltage.

A measurement method according to aspect 10 of the present invention is the measurement method according to any one of aspects 7 to 9, wherein the AC voltage is a triangular wave voltage, and a measurement circuit including a current/voltage conversion circuit and a full-wave rectification circuit. is used to generate the first DC voltage and the second DC voltage.

According to the above configuration, when a triangular wave voltage is input to the rotating plane electrode, the square wave current induced in the reference plane electrode can be easily converted into a DC voltage proportional to the amplitude of the square wave current. .

According to one aspect of the present invention, it is possible to realize an angle sensor that can accurately detect the rotation angle of a rotating body. Further, according to one embodiment of the present invention, it is possible to realize a mounting device capable of accurately detecting the orientation of an article. Further, according to one aspect of the present invention, it is possible to realize a measurement method capable of accurately detecting the rotation angle of a rotating body.

1 is a perspective view showing a configuration of essential parts of an angle sensor according to a first embodiment of the invention; FIG. A plane obtained when the rotation angle θ is 0°, which is an orthogonal projection of the reference plane electrode and the rotation plane electrode provided in the angle sensor shown in FIG. It is a diagram. The orthogonal projection of the reference plane electrode and the rotation plane electrode provided in the angle sensor shown in FIG. It is a diagram. 2 is a block diagram showing the configuration of a measurement system including the angle sensor shown in FIG. 1; FIG. FIG. 2 is a flow chart showing the flow of a measuring method using the angle sensor shown in FIG. 1; 2 is a perspective view of one implementation of the angle sensor shown in FIG. 1; FIG. FIG. 7 is a perspective view showing the configuration of a mounting device including the angle sensor shown in FIG. 6;

[Angle sensor]
An angle sensor 1 according to one embodiment of the present invention will be described with reference to FIG. FIG. 1 is a perspective view showing the main configuration of an angle sensor 1 according to this embodiment.

The angle sensor 1 is a sensor for detecting the rotation angle θ of the rotating body Y whose rotating shaft A is fixed to the reference body X. As shown in FIG. The angle sensor 1 includes a reference plane electrode 111 and a rotating plane electrode 121, as shown in FIG.

The reference plane electrode 111 is at least one plane electrode fixed to the reference body X. FIG. In this embodiment, the reference plane electrode 111 is composed of four plane electrodes each having a rectangular planar shape. These four plane electrodes are hereinafter also referred to as a first plane electrode 111a1, a second plane electrode 111b1, a third plane electrode 111a2, and a fourth plane electrode 111b2, respectively. The rotating plane electrode 121 is at least one plane electrode fixed to the rotating body Y. As shown in FIG. In the embodiment, the rotating plane electrode 121 is composed of one plane electrode having a rectangular plane shape.

The first plane electrode 111a1 and the second plane electrode 111b1, which constitute the reference plane electrode 111, are arranged side by side on the same plane. facing. Here, the arrangement of the first plane electrode 111a1 and the second plane electrode 111b1 is such that the long sides face each other in parallel in a plan view. The first planar electrode 111a1 and the second planar electrode 111b1 are separated from each other and, as a result, are insulated from each other.

Hereinafter, the area of the common portion (overlapping portion) between the orthogonal projection of the first plane electrode 111a1 onto the plane P1 and the orthogonal projection of the rotating plane electrode 121 onto the plane P1 will be referred to as a facing area Sa, and will be referred to as a second plane. The area of the common portion (overlapping portion) between the orthogonal projection of the electrode 111b1 onto the plane P1 and the orthogonal projection of the rotating plane electrode 121 onto the plane P1 is referred to as a facing area Sb. The capacitance Ca1 between the first plane electrode 111a1 and the rotating plane electrode 121 is proportional to the facing area Sa, and the capacitance Cb1 between the second plane electrode 111b1 and the rotating plane electrode 121 is proportional to the facing area Sb. proportional to

The third plane electrode 111a2 and the fourth plane electrode 111b2, which constitute the reference plane electrode 111, are arranged side by side on the same plane. facing. The arrangement of the third plane electrode 111a2 and the fourth plane electrode 111b2 is such that the long sides face each other in parallel in a plan view. The third planar electrode 111a2 and the fourth planar electrode 111b2 are spaced apart from each other and, as a result, insulated from each other. The third plane electrode 111a2 is connected in parallel to the first plane electrode 111a1, and the fourth plane electrode 111b2 is connected in parallel to the second plane electrode 111b1.

The planar view shape of the third planar electrode 111a2 is congruent with the planar view shape of the first planar electrode 111a1. The area of the common portion (overlapping portion) of the is the same as the facing area Sa described above. In addition, the planar view shape of the fourth planar electrode 111b2 is congruent with the planar view shape of the second planar electrode 111b1. The area of the common portion (overlapping portion) with the projection matches the facing area Sb described above. Therefore, the capacitance Ca2 between the third plane electrode 111a2 and the rotating plane electrode 121 is proportional to the facing area Sa, and the capacitance Cb2 between the fourth plane electrode 111b2 and the rotating plane electrode 121 is proportional to the facing area Sa. It is proportional to the area Sb. Further, the combined capacitance Ca of the capacitances Ca1 and Ca2 is proportional to the facing area Sa, and the combined capacitance Cb of the capacitances Cb1 and Cb2 is proportional to the facing area Sb.

When the rotor Y rotates in the direction in which the rotation angle θ increases, the facing area Sa increases and the facing area Sb decreases, resulting in an increase in combined capacitance Ca and a decrease in combined capacitance Cb. Conversely, when the rotating body Y rotates in a direction in which the rotation angle θ decreases, the facing area Sa decreases and the facing area Sb increases, resulting in a decrease in combined capacitance Ca and an increase in combined capacitance Cb. Therefore, the rotation angle θ corresponds one-to-one with the difference Ca-Cb between the combined capacitance Ca and combined capacitance Cb. Therefore, the rotation angle θ can be specified based on the difference Ca−Cb between the combined capacitance Ca and the combined capacitance Cb, or a physical quantity corresponding to the difference Ca−Cb on a one-to-one basis.

The angle sensor 1 can be constructed without using semiconductor components. Therefore, the angle sensor 1 can be suitably used even in a radiation environment. In addition, the angle sensor 1 can be used in a high-temperature environment (eg, an environment of 270° C. or higher), a low-temperature environment (eg, an environment of −268° C. or lower), a high-pressure environment (eg, an environment of 10 atm or higher), and a low-pressure environment (eg, (in a vacuum) can also be suitably used.

In addition, in the present embodiment, a mode (hereinafter also referred to as "mode C") in which the reference plane electrode 111 is composed of four plane electrodes is adopted, but the present invention is not limited to this.

For example, it is also possible to employ a mode (hereinafter also referred to as "mode A") in which the reference plane electrode 111 is composed of a single plane electrode (for example, the first plane electrode 111a1). In this case, the rotation angle .theta. Therefore, it is possible to specify the rotation angle θ based on the capacitance or a physical quantity in one-to-one correspondence with the capacitance.

Alternatively, there is a mode in which the reference plane electrode 111 is composed of two plane electrodes (for example, a first plane electrode 111a1 and a second plane electrode 111b1) arranged side by side on the same plane (hereinafter also referred to as "mode B"). ) can also be adopted. In this case, the rotation angle θ is paired with the difference (for example, the difference Ca1−Cb1) between the capacitances (for example, the capacitance Ca1 and the capacitance Cb1) between the two planar electrodes and the rotating electrode 12. corresponds to one. Therefore, it is possible to specify the rotation angle θ based on the difference in capacitance or a physical quantity corresponding to the difference one-to-one.

In addition to the aspect B in which the reference plane electrode 111 is configured by two plane electrodes arranged side by side on the same plane, the mode in which the reference plane electrode 111 is configured by two plane electrodes is also available. The electrode 111 is composed of two plane electrodes (for example, a first plane electrode 111a1 and a third plane electrode 111a2, or a second plane electrode 111b1 and a fourth plane electrode 111b2) facing each other with a rotating plane electrode 121 interposed therebetween. There is an aspect B'.

Note that, in mode B in which the reference plane electrode 111 is formed by two plane electrodes arranged on the same plane, the rotation angle is more accurate than in mode A in which the reference plane electrode 111 is formed by one plane electrode. There is an advantage that it becomes possible to specify θ. The reason is that it becomes possible to differentially specify the rotation angle θ.

Further, in the mode C in which the reference plane electrode 111 is composed of four plane electrodes, the rotation is more accurate than in the mode B in which the reference plane electrode 111 is composed of two plane electrodes arranged on the same plane. There is an advantage that it becomes possible to specify the angle θ. The reason is as follows.

That is, when adopting the mode B in which the reference plane electrode 111 is composed of two plane electrodes arranged on the same plane, the difference in capacitance between the two plane electrodes and the rotating plane electrode 121 is It also changes when the rotation plane electrode 121 is tilted. For example, when the rotating plane electrode 121 approaches one plane electrode (for example, the first plane electrode 111a1) and tilts in a direction away from the other plane electrode (for example, the second plane electrode 111b1), the one plane electrode and rotating plane electrode 121 (eg, capacitance Ca1) increases, and the capacitance (eg, capacitance Cb1) between the other plane electrode and rotating plane electrode 121 increases. As it decreases, the capacitance difference (eg, the difference Ca1-Cb2), which is the former minus the latter, increases. Therefore, the inclination of the rotating plane electrode 121 is likely to be an error factor in specifying the rotation angle θ.

On the other hand, when adopting mode C in which the reference plane electrode 111 is composed of four plane electrodes, the difference Ca−Cb between the combined capacitance Ca and the combined capacitance Cb is constant even if the rotating plane electrode 121 is tilted. or kept substantially constant. For example, when the rotating plane electrode 121 approaches the first plane electrode 111a1 and tilts away from the second plane electrode 111b1, the rotating plane electrode 121 moves away from the third plane electrode 111a2 and approaches the fourth plane electrode 111b2. Therefore, the capacitance Ca1 increases and the capacitance Cb1 decreases, and at the same time the capacitance Ca2 decreases and the capacitance Cb2 increases. is kept constant so that the difference Ca-Cb is also kept constant or substantially constant. Therefore, the tilt of the rotating plane electrode 121 is unlikely to cause an error in specifying the rotation angle θ.

In addition, when adopting the mode B in which the reference plane electrode 111 is composed of two plane electrodes arranged on the same plane, the difference in capacitance between the two plane electrodes and the rotating plane electrode 121 is It also changes when the rotating plane electrode 121 translates. For example, when the rotating plane electrode 121 approaches two plane electrodes (for example, the first plane electrode 111a1 and the second plane electrode 111b1) by ε, the capacitance between each plane electrode and the rotating plane electrode 121 is (For example, the capacitance Ca1 and the capacitance Ca2) are multiplied by d/(d-ε), so the difference between their capacitances (for example, the difference Ca1-Ca2) is also d/(d-ε). become. Here, d is the distance from the reference plane electrode 111 to the rotating plane electrode 121 before translation. Therefore, the parallel movement of the rotating plane electrode 121 can also be an error factor in specifying the rotation angle θ.

On the other hand, when adopting mode C in which the reference plane electrode 111 is composed of four plane electrodes, the rotating plane electrode 121 approaches the first plane electrode 111a1 and the second plane electrode 111b1 by ε, and at the same time The electrode 121 moves away from the third plane electrode 111a2 and the fourth plane electrode 111b2 by ε. Therefore, the capacitances Ca1 and Cb1 between the first plane electrode 111a1 and the second plane electrode 111b1 and the rotating plane electrode 121 are multiplied by d/d−ε, and at the same time, the third plane electrode 111a2 and the fourth plane electrode The electrostatic capacitances Ca2 and Cb2 between 111b2 and rotating plane electrode 121 are increased by d/d+ε times. At this time, the combined capacitances Ca and Cb are respectively multiplied by {d/(d−ε)}×{d/(d+ε)}, and as a result, the difference Ca−Cb is also {d/(d−ε)} ×{d/(d+ε)} times. Since 0<d/(d+ε)<1, {d/(d−ε)}×{d/(d+ε)}<d/(d−ε). Therefore, the parallel movement of the rotating plane electrode 121 is less likely to cause an error than in the case of adopting the mode B in which the reference plane electrode 111 is composed of two plane electrodes arranged on the same plane.

[Features of angle sensor]
Features of the angle sensor 1 according to this embodiment will be described with reference to FIGS. 2 and 3. FIG. 2 and 3 are plan views showing orthographic projections of the reference plane electrode 111 and the rotation plane electrode 121 onto the plane P perpendicular to the rotation axis A of the rotating body Y. FIG. Here, the plane P may be the plane P1 described above, the plane P2 described above, or another plane perpendicular to the rotation axis A of the rotating body Y.

The orthogonal projection of the first planar electrode 111a1 onto the plane P and the orthogonal projection of the third planar electrode 111a2 onto the plane P match each other (they overlap each other just enough). Therefore, in FIGS. 2 and 3, these orthogonal projections are illustrated as a single orthogonal projection OP111a. The facing area Sa described above is nothing but the area of the intersection (OP111a∩OP121) between this orthogonal projection OP111a and the orthogonal projection OP121 of the rotating plane electrode 121 onto the plane P. Further, the orthogonal projection of the second plane electrode 111b1 onto the plane P and the fourth plane electrode 111b2 onto the plane P match each other (they overlap each other just enough). Therefore, in FIGS. 2 and 3, these orthogonal projections are shown as a single orthogonal projection OP111b. The facing area Sb described above is nothing but the area of the common portion (OP111b∩OP121) between this orthogonal projection OP111b and the orthogonal projection OP121 of the rotating plane electrode 121 onto the plane P.

A feature of the angle sensor 1 is that the intersection OP111∩OP121 between the orthogonal projection OP111 of the reference plane electrode 111 onto the plane P and the orthogonal projection OP121 of the rotating plane electrode 121 onto the plane P rotates when θ is 0°. at a point sufficiently spaced from axis A; More specifically, let d1 be the distance from the axis of rotation A to the point closest to the axis of rotation A on the common portion OP111∩OP121, and let d1 be the distance from the axis of rotation A to the point furthest from the axis of rotation on the common portion OP111∩OP121. is the distance d2, and d2−d1≦d1 is satisfied when θ is 0°. Here, the orthogonal projection OP111 of the reference plane electrode 111 onto the plane P refers to the union OP111a∪OP111b of the orthogonal projection OP111a and the orthogonal projection OP111b. This feature enables the angle sensor 1 to accurately detect the rotation angle θ. This is because the amount of variation per unit rotation angle of the facing areas Sa and Sb is larger than when d1<d2−d1, and as a result, the amount of variation per unit rotation angle of the capacitance difference Ca−Cb is d1< This is because it is larger than when d2-d1.

FIG. 2 illustrates the arrangement of the orthogonal projection OP111 and the orthogonal projection OP121 on the plane P realized when the rotation angle θ is 0°. FIG. 3 illustrates the arrangement of the orthogonal projection OP111 and the orthogonal projection OP121 on the plane P realized when the rotation angle θ is 5°.

It should be noted that the fact that the amount of variation per unit rotation angle of the facing area Sa is increased due to the above-mentioned features can also be confirmed by the following discussion. It should be noted that in the following discussion it is assumed that the first planar electrode 111a is rectangular with width w and the rotating planar electrode 121 is rectangular with height h (see FIG. 2).

Assuming that the distance from the rotation axis A to the rotation plane electrode 121 is L (see FIG. 2), the facing area Sa when the rotation angle is θ is represented by the following formula (1). Therefore, the variation amount dSa/dθ of the facing area Sa per unit rotation angle when the rotation angle is θ is represented by the following formula (2), and the variation per unit rotation angle when the rotation angle is 0 is The variation dSa/dθ (θ=0°) of the facing area Sa is represented by the following formula (3).

The variation dSa/dθ (θ=0°) serves as an index of the sensitivity of the angle sensor 1 . That is, the above formula (3) shows that the sensitivity of the angle sensor 1 increases as the distance L (corresponding to the distance d1) increases. In particular, when w≦L (corresponding to d2−d1≦d1), the variation dSa/dθ (θ=0°) is 3w ² /2 or more. Therefore, by appropriately adjusting the width w of the first plane electrode 111a, it is possible to easily realize the angle sensor 1 having a desired sensitivity. If 2×(d2−d1)≦d1, an angle sensor 1 with even higher sensitivity can be realized, and if 3×(d2−d1)≦d1, an angle sensor with even higher sensitivity can be achieved. can be realized. According to experiments conducted by the inventors, it has been confirmed that an angle sensor 1 having an angular resolution of 2 μrad at −2.7°≦θ≦+2.7° can be realized as an example.

〔Measuring method〕
A measurement method MM according to an embodiment of the present invention will be described with reference to FIGS. 4 and 5. FIG.

First, the measurement system MS used to implement the measurement method MM will be described with reference to FIG. FIG. 4 is a block diagram showing the configuration of the measurement system MS.

As shown in FIG. 4, the measurement system MS includes a power supply device 2, a measurement circuit 3, and a computer 4 in addition to the angle sensor 1 described above.

The power supply device 2 is a device for inputting an AC voltage to the rotating plane electrode 121 of the angle sensor 1 . In this embodiment, the power supply device 2 inputs an AC voltage V to one plane electrode that constitutes the rotating plane electrode 121 . In this embodiment, as the AC voltage V, a triangular wave voltage is used.

When an AC voltage is input to the rotation plane electrode 121 of the angle sensor 1 , an AC current is induced in the reference plane electrode 111 of the angle sensor 1 . In this embodiment, alternating currents Ia1, Ia2, Ib1, and Ib2 are induced in the four plane electrodes 111a1, 111a2, 111b1, and 111b2 that constitute the reference plane electrode 111, respectively. When the AC voltage V input to the rotating plane electrode 121 is a triangular wave voltage, the AC current induced in the reference plane electrode 111 becomes a square wave current.

The measurement circuit 3 is a circuit for converting an alternating current induced in the reference plane electrode 111 of the angle sensor 1 into a direct voltage. In this embodiment, the measurement circuit 3 (1) converts the alternating currents Ia1 and Ia induced in the two plane electrodes 111a1 and 111a2 forming the reference plane electrode 111 into the sum current Ia of these alternating currents Ia1 and Ia2. =Ia1+Ia2, and (2) alternating currents Ib1 and Ib2 induced in the two plane electrodes 111b1 and 111b2 constituting the reference plane electrode 111 are transformed into these alternating currents Ib1 and Ib2. is converted into a DC voltage Vb proportional to the amplitude of the sum current Ib=Ib1+Ib2.

For example, as shown in FIG. 4, the measuring circuit 3 having such functions includes a current/voltage conversion circuit 31a connected to the first plane electrode 111a1 and the third plane electrode 111a2, and a current/voltage conversion circuit 31a connected to the current/voltage conversion circuit 31a. a full-wave rectifier circuit 32a, a current/voltage converter circuit 31b connected to the second plane electrode 111b1 and the fourth plane electrode 111b2, and a full-wave rectifier circuit 32b connected to the current/voltage converter circuit 31b Can be configured. For example, transimpedance amplifiers can be used as the current/voltage conversion circuits 31a and 31b. For example, absolute value circuits can be used as the full-wave rectifier circuits 32a and 32b. In this embodiment, since a triangular wave voltage is used as the AC voltage V, the output voltage of the measuring circuit 3 is a DC voltage that does not contain ripple components or contains a small amount of ripple components. Therefore, it is possible to realize a measurement system MS with a fast response speed (a short time from when the rotation angle θ changes to when the rotation angle θ is specified).

The electronic calculator 4 is a device for specifying the rotation angle θ based on the DC voltage obtained by the measuring circuit 3 . In this embodiment, the computer 4 identifies the rotation angle θ based on the DC voltages Va and Vb obtained by the measurement circuit 3 . The value of the rotation angle θ is, for example, the ratio V − /V + of the sum voltage V ⁺ =Va+Vb of the DC voltages Va and Vb to the difference voltage V ⁻ of the DC voltages Va and Vb ⁼ Va ⁻ Vb. corresponds to In this embodiment, the computer 4 uses this correspondence relationship to identify the rotation angle θ. Therefore, the storage 41 of the computer 4 stores a table T that associates the values of the ratio V ⁻ /V ⁺ with the values of the rotation angle θ. The processor 42 of the computer 4 performs (a) a process of calculating the ratio V ⁻ /V ⁺ from the DC voltages Va and Vb, and (b) specifying the rotation angle θ corresponding to the ratio V ⁻ /V ⁺ in the table T. Execute the processing to be performed.

Note that the processor 42 of the electronic computer 4 controls the amplitude of the output voltage of the power supply ² (that is, the rotation plane electrode 121 to It may have a function of feedback-controlling the amplitude of the AC voltage V to be input. In this case, the rotation angle θ corresponds one-to-one with the difference voltage V ⁻ =Va−Vb between the DC voltages Va and Vb. In this case, instead of the table T, the storage 41 of the computer 4 may store a table T' that associates the value of the difference voltage V ⁻ between the DC voltages Va and Vb with the value of the rotation angle θ. Also, in this case, instead of the above processes (a) and (b), the processor 42 performs (c) a process of calculating the difference voltage ^V- from the DC voltages Va and Vb, and (d) in the table T' A process of specifying the rotation angle θ corresponding to the differential voltage V ⁻ may be executed.

Next, the measurement method MM will be described with reference to FIG. FIG. 5 is a flow diagram showing the flow of the measurement method MM.

The measurement method MM includes an input step S1, a conversion step S2, and an identification step S3, as shown in FIG.

The power supply device 2 performs an input step S<b>1 of inputting an AC voltage to the rotation plane electrode 121 of the angle sensor 1 . In the input step S1 according to the present embodiment, as described above, an AC voltage V (triangular wave voltage) is input to one plane electrode that constitutes the rotating plane electrode 121 . The input step S1 is continuously performed throughout the measurement period, as shown in FIG.

The measuring circuit 3 performs a conversion step S2 of converting the alternating current induced in the reference plane electrode 111 of the angle sensor 1 into a direct voltage V. FIG. In the conversion step S2 according to the present embodiment, as described above, (1) the alternating currents Ia1 and Ia2 (square wave currents) induced in the two plane electrodes 111a1 and 111a2 constituting the reference plane electrode 111 are These alternating currents Ia1 and Ia2 are converted into a DC voltage Va proportional to the amplitude of the sum current Ia=Ia1+Ia2, and (2) an alternating current Ib1 induced in the two plane electrodes 111b1 and 111b2 constituting the reference plane electrode 111. , Ib2 (square wave current) are converted into a DC voltage Vb proportional to the amplitude of the sum current Ib=Ib1+Ib2 of these alternating currents Ib1 and Ib2. The conversion step S2 is continuously performed throughout the measurement period, as shown in FIG.

The computer 4 carries out an identification step S3 of identifying the rotation angle θ based on the DC voltage obtained by the measurement circuit 3 . In the specifying step S3 according to the present embodiment, the rotation angle θ is specified based on the DC voltages Va and Vb obtained by the measuring circuit 3, as described above. For example, when using a table T that associates values of the ratio V ⁻ /V ⁺ with values of the rotation angle θ, (a) a process of calculating the ratio V ⁻ /V ⁺ from the DC voltages Va and Vb; ) A process is performed to identify the rotation angle θ in table T corresponding to the ratio V ⁻ /V ⁺ . Alternatively, when using a table T′ that associates the value of the differential voltage V ⁻ with the value of the rotation angle θ, (c) a process of calculating the differential voltage V ⁻ from the DC voltages Va and Vb, and (d) the table T ' is performed to identify the rotation angle θ corresponding to the differential voltage V ⁻ . As shown in FIG. 5, the identifying step S3 is periodically performed at each sampling timing during the measurement period. When using the table T' that associates the value of the difference voltage ^V- with the value of the rotation angle θ, feedback control for fixing the sum voltage V ⁺ of the DC voltages Va and Vb to a predetermined value is performed. is continuously performed throughout the measurement period.

Here, the measurement method MM according to the mode C in which the reference plane electrode 111 is composed of four plane electrodes has been described, but the present invention is not limited to this.

For example, when mode A is adopted in which the reference plane electrode 111 is composed of a single plane electrode, the AC current induced in this plane electrode is converted into a DC voltage proportional to its amplitude, and this DC voltage The rotation angle .theta.

Alternatively, when mode B is adopted in which the reference plane electrode 111 is composed of two plane electrodes (for example, a first plane electrode 111a1 and a second plane electrode 111b1), alternating currents induced in these plane electrodes are , is converted into a DC voltage proportional to its amplitude, and the rotation angle θ is specified based on the difference between these DC voltages.

[Example of realization of angle sensor]
An implementation example of the angle sensor 1 (hereinafter referred to as the angle sensor 100) will be described with reference to FIG. FIG. 6 is a perspective view showing the configuration of the angle sensor 100. As shown in FIG.

The angle sensor 100 comprises a reference module 110 and a rotation module 120, as shown in FIG.

The reference module 110 is a module fixed to the reference body X. FIG. In addition to the reference plane electrode 111 described above, the reference module 110 includes an output terminal 112 connected to the reference plane electrode 111, and a housing 113 for housing the reference plane electrode 111 and for mounting the output terminal 112. I have.

In this embodiment, the housing 113 includes (1) a first side wall 113a, (2) a second side wall 113b that intersects with the first side wall 113a, and (3) a side wall that intersects with the second side wall 113b and faces the first side wall 113a. Third side wall 113c, (4) A box-shaped housing including a fourth side wall 113d intersecting with the third side wall 113c and the first side wall 113a and facing the second side wall 113b is used. A first plane electrode 111a1 and a second plane electrode 111b1, which constitute the reference plane electrode 111, are fixed to the inner surface of the first side wall 113a. A third plane electrode 111a2 and a fourth plane electrode 111b2, which constitute the reference plane electrode 111, are fixed to the inner surface of the third side wall 113c. The output terminal 112 is configured by a first output terminal 112a connected to the first plane electrode 111a1 and the third plane electrode 111a2 and a second output terminal 112b connected to the second plane electrode 111b1 and the fourth plane electrode 111b2. It is configured. The first output terminal 112a and the second output terminal 112b are attached to the outer surface of the second side wall 113b so as to protrude in a direction perpendicular to the surface. An opening 113d1 for inserting the rotating plane electrode 121 is formed in the fourth side wall 113d.

The rotating module 120 is a module fixed to the rotating body Y. As shown in FIG. The rotating module 120 includes, in addition to the rotating plane electrode 121 described above, an input terminal 122 connected to the rotating plane electrode 121 and a housing 123 for mounting the rotating plane electrode 121 and the input terminal 122 .

In this embodiment, the housing 123 includes (1) a first side wall 123a, (2) a second side wall 123b that intersects with the first side wall 123a, and (3) intersects with the second side wall 123b and faces the first side wall 123a. Third side wall 123c, (4) fourth side wall 123d that intersects with third side wall 123c and first side wall 123a and faces second side wall 123b, (5) box shape including top plate 123e that intersects with these side walls 123a to 123d I am using a casing. The rotating plane electrode 121 is attached to the outer surface of the top plate 123e so as to protrude in a direction perpendicular to the surface. The input terminal 122 is connected to one plane electrode that constitutes the rotating plane electrode 121 . The input terminal 122 is attached to the outer surface of the second side wall 123b so as to protrude in a direction perpendicular to the surface.

As shown in FIG. 6, the angle sensor 100 is used with the rotating plane electrode 121 attached to the top plate 123e of the rotating module 120 inserted into the opening 113d1 formed in the fourth side wall 113d of the reference module 110. be. In this state, the arrangement shown in FIG. 6 is realized between the reference plane electrode 111 and the rotating plane electrode 121 .

(mounting device with angle sensor)
A mount device 200 including the angle sensor 100 will be described with reference to FIG. FIG. 7 is a perspective view showing the configuration of the mounting device 200. As shown in FIG.

A mounting device 200 is a device for rotatably mounting a disk-shaped mirror. The mounting device 200 includes a frame 201, a first gimbal 202, and a second gimbal 203 in addition to the two angle sensors 100, as shown in FIG.

The first gimbal 202 is arranged inside the frame 201 and rotatably attached to the frame 201 . A rotation axis A<b>1 of the first gimbal 202 is fixed to the frame 201 . The second gimbal 203 is arranged inside the first gimbal 202 and rotatably attached to the first gimbal 202 . A rotation axis A<b>2 of the second gimbal 203 is fixed to the first gimbal 202 . The rotation axis A1 of the first gimbal 202 and the rotation axis A2 of the second gimbal 203 are orthogonal to each other. The mirror is fixed (for example, screwed) to the second gimbal 203 .

One of the two angle sensors 100 is used to detect the rotation angle θ1 of the first gimbal 202 with respect to the frame 201 . A reference module 110 that constitutes the angle sensor 100 is fixed to the frame 201 . On the other hand, the rotation module 120 that constitutes the angle sensor 100 is fixed to the first gimbal 202 .

The other of the two angle sensors 100 is used to detect the rotation angle θ2 of the second gimbal 203 with respect to the first gimbal 202. A reference module 110 that constitutes the angle sensor 100 is fixed to the first gimbal 202 . On the other hand, the rotation module 120 that constitutes the angle sensor 100 is fixed to the second gimbal 203 .

The mounting device 200 allows the mirror to be rotatably mounted and the orientation of the mirror to be accurately detected by the two angle sensors 100 . Since the angle sensor 100 is realized without using semiconductor components, the mounting device 200 can be suitably used even in a radiation environment.

In this embodiment, the mounting device 200 suitable for mounting a mirror has been described, but the article to be mounted is arbitrary and is not limited to mirrors. Articles other than mirrors that are mounted on the mounting device 200 include, for example, optical components such as lenses, cameras, optical sensors, and optical fibers. Also, an article other than an optical component may be used as long as the article requires attitude control.

[Additional notes]
The present invention is not limited to the above-described embodiments, but can be modified in various ways within the scope of the claims, and can be obtained by appropriately combining technical means disclosed in different embodiments. is also included in the technical scope of the present invention.

1 angle sensor 100 angle sensor 110 reference module 111 reference plane electrode 111a1 first plane electrode 111b1 second plane electrode 111a2 third plane electrode 111b2 fourth plane electrode 112 output terminal 113 housing 120 rotation module 121 rotation plane electrode 122 input terminal 123 Housing 2 Power supply 3 Measuring circuit 4 Computer 200 Mounting device 201 Frame 202 First gimbal 203 Second gimbal

Claims (6)

An angle sensor for detecting a rotation angle θ of a rotating body whose rotating shaft is fixed to a reference body,
a reference plane electrode fixed to the reference body;
a rotating plane electrode fixed to the rotating body, the rotating plane electrode facing the reference plane electrode across a plane orthogonal to the rotation axis;
The reference plane electrode includes a first plane electrode and a second plane electrode arranged side by side on a plane facing one surface of the rotation plane electrode, and a plane facing the other side of the rotation plane electrode. a third planar electrode and a fourth planar electrode arranged side by side;
The third planar electrode is connected in parallel to the first planar electrode,
The fourth planar electrode is connected in parallel to the second planar electrode,
For the intersection of the orthogonal projection of the reference plane electrode onto the plane and the orthogonal projection of the rotation plane electrode onto the plane, let d1 be the distance from the axis of rotation to the nearest point on the intersection to the axis of rotation. , where d2 is the distance from the rotation axis to the farthest point from the rotation axis in the common portion, and d2−d1≦d1 is satisfied when θ is 0°;
An angle sensor characterized by: a frame;
a first gimbal whose rotation axis is fixed to the frame;
a second gimbal having a rotating shaft fixed to the first gimbal for mounting an article;
a first angle sensor that detects the rotation angle θ of the first gimbal ;
a second angle sensor that detects the rotation angle θ′ of the second gimbal ;
The first angle sensor is
a reference plane electrode fixed to the frame;
a rotating plane electrode fixed to the first gimbal, the rotating plane electrode facing the reference plane electrode across a plane perpendicular to the rotation axis of the first gimbal;
For the intersection of the orthogonal projection of the reference plane electrode onto the plane and the orthogonal projection of the rotation plane electrode onto the plane, let d1 be the distance from the axis of rotation to the point closest to the axis of rotation in the intersection. , where d2 is the distance from the rotation axis to the farthest point from the rotation axis in the common portion, and d2−d1≦d1 is satisfied when θ is 0°,
The second angle sensor is
a reference plane electrode fixed to the first gimbal;
a rotating plane electrode fixed to the second gimbal, the rotating plane electrode facing the reference plane electrode across a plane orthogonal to the rotation axis of the second gimbal;
For the intersection of the orthogonal projection of the reference plane electrode onto the plane and the orthogonal projection of the rotation plane electrode onto the plane, the distance from the axis of rotation to the point closest to the axis of rotation in the intersection is d1'. and the distance from the rotation axis to the farthest point in the common portion from the rotation axis is d2', and d2'-d1'≤d1' is satisfied when θ' is 0°,
A mounting device characterized by: the article is an optical component ,
3. The mounting device according to claim 2 , wherein: A measuring method for measuring the rotation angle θ of the rotating body using the angle sensor according to claim 1 ,
inputting an alternating voltage to the rotating plane electrode;
A first DC voltage proportional to the amplitude of the sum of the alternating currents induced in the first planar electrode and the third planar electrode and the sum of the alternating currents induced in the second planar electrode and the fourth planar electrode determining the rotation angle θ based on the difference from a second DC voltage proportional to the amplitude of
A measuring method characterized by: further comprising controlling the amplitude of the AC voltage input to the rotating plane electrode such that the sum of the first DC voltage and the second DC voltage is constant;
The measuring method according to claim 4 , characterized in that: The AC voltage is a triangular wave voltage,
generating the first DC voltage and the second DC voltage using a measurement circuit including a current/voltage conversion circuit and a full-wave rectification circuit;
6. The measuring method according to claim 4 or 5 , characterized in that:

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