JPH059603Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an angle detector used in control systems such as robots or servo systems, and its purpose is to have a wide detection angle range, high reliability, long life, and a simple structure. The present invention provides a novel angle detector that is easy to manufacture and can be manufactured at low cost, is compact, and can be easily adjusted.

In the angle detector of the present invention, a rotating conductor is fixed to the angle detection shaft, and this rotating conductor is rotatably provided between the conductors forming two capacitors, which are placed facing each other with a gap between them. A bridge circuit is constructed by connecting two resistors, and a potential difference due to unbalance is created in the bridge circuit by using the change in capacitance of the capacitor according to the rotation angle displacement of the angle detection axis. It can be called a differential capacitance method that measures the rotational angular displacement of the
Moreover, since the only mechanical contact part of the movable part in the main component is the bearing of the support body that pivotally supports the angle detection shaft, it can be said to have a non-contact structure.

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

FIG. 1 is a partially cutaway side view of the main structure of the angle detector of the present invention, that is, a portion forming a variable capacitor, and FIG. 2 is an exploded perspective view thereof. In these figures, 1 is one support made of an insulating plate, 2 is the other support made of an insulating plate, and these supports 1 and 2 are made of a frame having a certain thickness so as to maintain a certain distance. Fixed on both sides of 3. 4 is one support 1
It is one conductor arranged on the inner surface of the conductor, and has a circular shape, and is easily manufactured by methods such as etching, applying conductive paint, metal vapor deposition, and pasting of metal foil or metal plate. be able to. 5 is the other conductor disposed on the inner surface of the other support 2 opposite to the one conductor 4, and the two semicircular conductors 5a and 5b are electrically insulated from each other with a slight gap between them. The other conductor 5 or 5a, 5b and the one conductor 4
When viewed from above, they are arranged in an overlapping state with a gap 6 between them. Further, the other conductor 5 can be easily manufactured using the same method as the one conductor 4. Reference numeral 7 designates an angle detection shaft, which penetrates through the center of one conductor 4 and the other conductor 5 and is rotatably supported by bearings 8 and 9 provided on one support 1 and the other support 2. . bearing 8,
Since numeral 9 is the only movable contact part of the angle detection shaft 7, an appropriate bearing must be selected in this part so that there is no loss due to friction in order to improve the detection accuracy. 10 is a rotating conductor whose center is fixed to the angle detection shaft 7 and is arranged between one conductor 4 and the other conductor 5, and is rotatable without contacting these conductors 4 and 5; , 5 is formed by applying a conductor to the outer surface of half of a disk-shaped insulating substrate made of a material with a relative dielectric constant as small as possible and having a thickness smaller than the length of the gap 6 between the conductors. The conductor portion of this rotating conductor 10 can also be easily manufactured in the same manner as the one conductor 4 and the other conductor 5 described above. The purpose of this rotating conductor 10 is that its conductor portion is interposed between one conductor 4 and the other conductor 5, which serve as electrodes of a capacitor, to reduce the distance between the electrodes and vary the capacitance. In that sense, the other half of the conductor 10 that is not provided with a conductor has no significance electrically, but it can make the rotation of the angle detection shaft 7 well-balanced.
Of course, for the above reasons, the insulating substrate of the rotating conductor 10 may be formed in the shape of a semi-disk in the area where the conductor is to be applied, and a balancer may be installed on the angle detection shaft 7 on the opposite side to stabilize the rotation. can.

In addition, since the two capacitors with the above structure are connected in series when assembling a bridge circuit, one conductor 4 is formed in a circular shape, but like the other conductor 5, two semicircular ones are formed. They can also be combined.
In that case, one conductor 4 can be manufactured to have exactly the same shape as the other conductor 5, although electrical connection must be made later. In this case, it goes without saying that the semicircular conductors of one conductor 4 and the other conductor 5 must be arranged so as to overlap with each other.

A bridge circuit is constructed by combining the above-described structure with a resistor R and a variable resistor αR as shown in FIG. In other words, _the capacitor C ₁ shown in FIG. It is formed by the conductor 4 and the other conductor 5b of the other conductors 5, and these capacitors
C ₁ and C ₂ are formed into variable capacitors by the presence of the rotating conductor 10. A bridge circuit is then assembled by externally attaching a separately prepared resistor R and variable resistor αR to these. In this bridge circuit, two variable capacitors C ₁ ,
Apply AC voltage e, (t) to the connection points a and b at both ends of C ₂ and resistors R and αR, and connect the two series-connected variable capacitors C ₁ and C ₂ and resistors R and αR to the connection point a. A potential difference e ₀ corresponding to the rotational angular displacement of the angle detection shaft 7 is generated from both ends of the load resistor R ₀ connected to
(t). In addition, load resistance R ₀
is not necessarily necessary.

Next, in the bridge circuit described above, the angle detection axis 7
The relationship between the rotational angular displacement θ and the potential difference e ₀ ,t is as follows.

However, one conductor 4, the other conductor 5a, 5b
The radius of the conductor portion of the rotating conductor 10 is r, the thickness of the conductor portion of the rotating conductor 10 is d, and the length of the gap 6 between one conductor 4 and the other conductors 5a and 5b is d+Δ.

Therefore, first, from e,(t) of the bridge circuit, e ₀ ,
(t), E ₀ (S) / E (S) = kS / 1 + ST ..., and K = K ₀ R ₀ / 1 + α・αC ₂ −C ₁ /C ₁ +C ₂ = K _t (α
C ₂ − C ₁ )... However, K _t =K ₀ R ₀ /(1+α)(C ₁ +C ₂ ), and this value is a constant as will become clear later.

On the other hand, as shown in FIG. 4, when the rotating conductor 10, that is, the angle detection axis 7 is displaced by θ, the capacitances of the variable capacitors C ₁ and C ₂ are as follows.

C ₁ = ε ₀ r ² θ/2Δ+ε ₀ r ² (π−θ)/2d... C ₂ =ε ₀ r ² (π−θ)/2Δ+ε ₀ r ² θ/2d... By substituting, K=K _t (αC ₂ −C ₁ )=K _t ε ₀ r ² /2 {(α+1)
(θ/Δ−θ/d)+π(α/d−1/Δ)}... Here, if α=d/Δ, the formula is K=K _t・ε ₀ r ² /2・d ² −Δ ² /dΔ ² θ ......, and K _t・ε ₀ r ² /2・d ² −Δ ² /dΔ ² in the formula becomes a constant. From this, the value of K representing the amplitude of e ₀ , (t) is In other words, the rotational angular displacement θ of the angle detection shaft 7 and the output e ₀ (t) of the bridge circuit are proportional to θ.

Furthermore, in the equation, if d is set large and Δ is set small, the constant applied to θ becomes large, and the proportional coefficient can be made large.

Note that from the formula, C ₁ +C ₂ =ε ₀ r ² π/2 (1/Δ+1/d) ..., and the right side of the formula is a constant.

The relationship between θ and e ₀ , (t) is as shown in FIG.

In addition, the variable capacitors C ₁ and C ₂ in this invention
When considering the relationship between the machining accuracy and the detection accuracy of the detector in the structure of Another issue is whether the rotating conductor 10 can be fixed in a predetermined position between the one conductor 4 and the other conductor 5. However, the inventor has confirmed that even if the assembly accuracy is somewhat poor, the detection accuracy is hardly adversely affected.

For example, even if the rotating conductor 10 is fixed at an angle of 10 degrees to the angle detection axis 7, only a 1% error will occur in the detection accuracy, and the rotating conductor 10 must not touch one conductor 4 and the other conductor 5. There are no negative effects at all.

Next, FIG. 6 is an explanatory diagram of an example of an angle detection device using the detector of the present invention. The output from the detector is
Processed in the following order: AC amplifier, rectifier circuit, comparator,
Output. When configuring an angle detection device in this way, since the output of the detector of the present invention is AC, an AC amplifier is used for signal amplification, which causes a drift problem compared to a DC amplifier. In addition, by making the frequency characteristics of the AC amplifier narrow band corresponding to the oscillation frequency of the oscillator, drift, induction of commercial frequency voltage,
It has the advantage of cutting out high frequency noise. Furthermore, the rectifier circuit and comparator circuit with good linearity constituting the device can be easily manufactured with high precision.

Adjustment in the above angle detection device is made using variable resistor αR.
This is done using The method is to change θ by rotating the angle detection shaft 7, and at the angle θ ₀ where the amplitude of e ₀ is minimized, adjust the variable resistor αR to change α so that the amplitude of θ ₀ is minimized. . This state is θ ₀ = 0°
Make it. Then, for example, the gain of the AC amplifier is adjusted so that e ₀ at θ=±50° becomes a specified voltage.

Note that even if the detection angle range is narrow, measurements can be made easily by adjusting the gain of the AC amplifier to be large.

As mentioned above, the angle detector of the present invention has a large angle detection range that covers the entire range of 360°, and the mechanical contact part of the movable part in the main component of the variable capacitor is connected to the angle detection axis. During operation, one conductor (the electrode part) and the other conductor (the electrode part) are in a non-contact state with the rotating conductor (the movable part) only by the bearing of the support body that pivotally supports the detector, so the part that causes unreliability of the detector is The detector of the present invention is highly reliable and has a long service life because it uses only a bearing, and bearings are generally known to be highly reliable.

In addition, in the angle detector of the present invention, the variable capacitor, which is the main component, has an extremely simple structure, and the conductor of the electrode part is either vapor-deposited metal on an insulating base material, coated with conductive paint, or It can be easily formed by fixing suitable metals, etc., and does not require high assembly precision, so it can be manufactured at low cost, and the whole can be constructed in a cohesive and compact manner. .

Furthermore, the angle detector of the present invention has beneficial effects such as being able to be used conveniently according to the application by adjusting the variable resistor that makes up the bridge circuit and the gain of the amplifier connected to the output of the bridge circuit. .

[Brief explanation of the drawing]

Figure 1 is a partially cutaway side view of the main parts of the present invention, Figure 2 is an exploded perspective view, Figure 3 is a circuit diagram of the angle detector of the present invention, Figure 4 is an explanatory diagram of the variable capacitor, Figure 5 is a relationship diagram between the displacement θ of the angle detection axis in the angle detector and the detector output e ₀ , (t).
The figure is an explanatory diagram of an angle detection device using the detector of the present invention. 1... One support, 2... The other support, 4
... One conductor, 5, 5a, 5b ... Other conductor, 6 ... Gap, 7 ... Angle detection axis, 8, 9 ...
Bearing, 10...Rotating conductor, _C1 , _C2 ...Variable capacitor, R, αR...Resistor, a, b...Both end connection points, a', b'...Connection midpoint.

Claims (1)

[Claims for Utility Model Registration] (1) One support 1 and the other support 2 made of insulators arranged at regular intervals, and one circular conductor or two semicircular conductors. One conductor 4 arranged on the inner surface of the one support 1, with the conductors electrically insulated from each other and arranged in a circular shape.
and this one conductor 4, the two semicircular conductors are arranged facing each other with a gap 6 between them and are electrically insulated from each other so as to form a circular shape. The other conductor 5 arranged in The rotation conductor 10 has its center fixed to the angle detection shaft 7 and has a conductor in a semicircular shape with a thickness smaller than the length of the gap 6, and the conductor is arranged in the gap 6. Two variable capacitors C 1 _and C ₂ are formed using the conductor 4 of the other side and the other conductor 5 as electrodes, and two resistors are connected in series between the two variable capacitors C ₁ and C ₂ connected in series. R,
A bridge circuit is constructed by connecting αR, and the two variable capacitors connected in series are
AC voltage is applied to the connection points a and b at both ends of C ₁ , C ₂ and resistors R and αR, and the two connected in series are
An angle detection device characterized in that a potential difference corresponding to the rotational angular displacement of the angle detection shaft 7 is extracted from connection midpoints a′ and b′ of the variable capacitors C ₁ and C ₂ and the resistors R and αR. vessel. (2) The angle detector according to claim 1, wherein one of the two resistors αR is a variable resistor.