JPS6047901A - Angle converter - Google Patents

Abstract

PURPOSE:To improve the linearity characteristic and to enable the measurement of an input angle in a wide range of 0-360 deg. and the easy adjustment of assembly, by enabling the attainment of an output voltage proportional directly to the input angle, and by using a current fine adjustment circuit and a phase adjustment circuit for electrical adjustment. CONSTITUTION:Hall elements 2 and 3 are disposed perpendicular to each other on an axis 0 as the center and between permanent magnets 11 and 12, and an input rotational displacement theta enters the axis 0. Substantially equal magnetic flux densities B are applied to the Hall elements 2 and 3 respectively. An AC power circuit 4 drives the Hall element 2, while applying to the Hall element 3 an AC voltage having a phase shifted by 90 deg. through a phase shifter 41. The adjustment of a supply current is conducted by a current fine adjustment circuit 5, while the adjustment of the phase is conducted by a phase fine adjustment circuit 6. An output of an addition circuit 7 is connected to the SET side of a flip- flop circuit 83 through a comparator 81, while an output of the AC power circuit 4 is connected to the RESET side of said circuit 83 through a comparator 82.

Description

[Detailed description of the invention] The present invention relates to an angle converter.

More specifically, the present invention relates to an angle converter that outputs angular displacement as an electrical signal using a Hall element.

FIG. 1 is a diagram illustrating the principle of an angle converter using a Hall element that has been commonly used in the past.

In the figure, reference numeral 1 denotes a magnetic circuit consisting of a permanent magnet having an S pole and an N pole. Reference numeral 2 denotes a Hall element placed within the magnetic field of the magnetic circuit 1, which rotates around an axis of perpendicular to the plane of the paper according to an input angle θ.

In the above configuration, when the Hall element 2 rotates by θ angle according to the input angle θ, the voltage ■θ generated in the Hall element 2a is Vθ=■I sinθ (1) where: Product sensitivity of the Hall element (input Current 1mA Magnetic flux density 1k
G: Output voltage mv) B: Magnetic flux density E: Hall drive current θ: Input angle.

As a result, the output voltage V, is proportional to the sine of the input angle θ.

However, in general, an output proportional to the input angle θ is required, so the output must be linearized or a small angle must be made into a measurable range.

In this case, there is inevitably a problem that the linearity characteristics etc. are adversely affected and good characteristics cannot be obtained.

The present invention solves this problem.

The purpose of the present invention is to provide an input shaft to which rotational displacement is applied. center 1
A common magnetic flux density is applied to the two Hall elements arranged orthogonally to each other, and the direction of the magnetic flux is set relative to the Hall element K with respect to the input axis in accordance with the input rotation angle. and a magnetic circuit configured to rotate relative to each other.
an AC power circuit that applies an AC voltage having a phase difference of 0 degrees to each of the Hall elements; a current fine adjustment circuit provided between the AC power circuit and one of the Hall elements; and the AC power circuit. and the other of the Hall elements, an addition circuit for adding the output voltages of the two pole elements, and an output of the addition circuit and one of the outputs of the AC power supply circuit. Since the angle converter is configured such that an output voltage directly proportional to the input angle is obtained, the linearity characteristics are good.
A wide measurable range with an input angle of 0 to 360 degrees is obtained.
In addition, the practical difficulty of assembling two Hall elements accurately orthogonally can be overcome by electrical adjustment using a current fine adjustment circuit and a phase adjustment circuit. There is also K, which provides an easy angle converter.

FIG. 2 is an explanatory diagram of the configuration of an embodiment of the present invention.

In the figure, 1 is a magnetic circuit consisting of permanent magnets 11, 12 and a yoke 13. Permanent magnets 11 and 12 are attached to both ends of the U-shaped yoke 13, and are arranged so that a magnetic field is generated between the permanent magnets 11 and 12. Reference numeral 2.3 denotes a Hall element, which is arranged between the permanent magnets 11 and 12 and arranged orthogonal to each other with the axis 0 as the center, and the input rotational displacement θ is input to the axis OK. Therefore, hall element 2
, 3, a magnetic flux density B approximately equal to tl is added. FIG. 5 shows a block diagram of the electrical circuit of FIG. 2. Reference numeral 4 denotes an AC power supply circuit for AC driving the Hall elements 2 and 3, which not only drives the Hall element 2 but also applies an AC voltage to the Hall element 3 through a phase shifter 41 with a phase shift of 90 degrees. Reference numeral 5 denotes a current fine adjustment circuit, which is provided between the AC power supply circuit 4 and the Hall element 2, and adjusts the supplied current as described later. A phase fine adjustment circuit 6 is provided between the AC power supply circuit 4 and the Hall element 3, and performs phase adjustment as described later. 7 is hall element 2
．． In this case, the difference between the two outputs is calculated. Reference numeral 8 denotes phase difference detection means, which in this case consists of co/parators 81, 82, a flip-flop circuit '83, and a situation circuit 84. The output of the adder circuit 7 is
Flip-flop circuit 8 via controller (later 81)
The output of the AC power supply circuit 4 is connected to the SET side of the 7 lipfrog circuit 83O via the comparator 82.
Connected to the RESET side. The i side of the 7-lip flop circuit 83 is connected to an output terminal 85 via a smoothing circuit 84.

In the above configuration, in order to simplify the explanation, first, the operation of the flow fine adjustment circuit 5 and the phase fine adjustment circuit 6 will be described in the case where they are strong.

V-V si from the AC power supply circuit 4 to the Hall element 2
A voltage of nωt is applied and a current of 11 sinωt flows.

The Hall element 3 has a voltage Vl that is passed through the phase shifter 41.
ltx V cos (dt wo addition che2CO8ωt
A current flows through the current. When the input angle θ to the input shaft 0 is θ=0,
As shown in FIG. 4, if the Hall element 2 receives the magnetic flux at right angles, the Hall element 5 receives the magnetic flux in parallel. Input axis OK^ When the force angle θ is given, the magnetic flux densities applied to the Hall elements 2 and 3 are B cos θ and B, respectively, where B is the magnetic flux density near the center of the magnetic circuit.
s1nθ. Increase the product sensitivity of Hall Element Rei 3 to 1
．． 2, the output voltage of Hall element 3 is VV
is 2'3 V2= KIIIB sin ωt - cosθ= K
11□B (45in (ωt + θ)” 25in (a + - θ)) (2) ■3': 2 BCO 5 ωt -s
inθ=2I,B (4sin(ωt+θ)−4si
n (ω is - θ) I L3). To the adder circuit 7,
Taking the difference between outputs v2 and v3, K□Work□B≠ has 2Works 2B
Then, the difference v4 between both outputs is v4” KIIIB 5i
n(ωt-θ) (4). The waveforms of v4 and v1 voltages are shown in M5 diagram A).

When the v4 voltage is passed through the comparator 81, a waveform as shown in FIG. 5(C) is obtained, while when the ■ voltage is passed through the comparator 82, a waveform as shown in FIG. 5(B) is obtained. The output of comparators 81 and 82 is 7 rip 70. When added to the F-side circuit 83, the output from the F side has a waveform as shown in FIG. 5(d). This output can be passed through the smoothing circuit 84 to obtain a DC output Vo. The DC output vO is as shown in the following equation.

here T: period T1: Pulse width vs: amplitude Therefore, the output voltage V is proportional to the input angle θ.

is obtained.

As a result, the input angle can be proportionally converted into an output voltage. However, since the input angle is converted into a phase difference measurement, there is no non-linearity in principle.

- Fluctuations in the oscillation frequency ω do not affect measurement accuracy. ■
The input angle θ can be measured in the range of 0 to 360 degrees, and a large input span can be adopted.

In addition, comparator 8 is used as a zero crossing detector.
1.82, it is possible to obtain a structure in which fluctuations in oscillation amplitude do not cause errors.

However, in each actual assembly site, it is difficult to assemble the Hall elements 2.3 exactly orthogonally.
Practically speaking, this is close to impossible. This deviation from orthogonality results in a nonlinearity error.

Now, if Ω is the adjustment phase and θ is the assembly error angle, then the output v20"30 of the Hall elements 2 and 3 is V2O"K
IIIB sinωt cosθ (6) v3oIll
K2 engineering 2Bcos (ωt+Ω) sin (θ10>
(7) If the difference in the output of V2O"30 is V4O, it is 40
20 30 W KIIIB sin alt cos θ- to 2I2
B cos (ωt+Ω) sin (θ+θ) (8) Cos (ωt+Ω) sin (θ+θ)m(cos
ωt ・cosΩ−5inωt−SinΩ)x(si
nθcosθ+cos O-sin fj)wa co
s (lIt 9sinθC08QC08θ+cosω
t cosθQO8Ωsinθ−81nωt sinθ
5inQcosθ−81nωt cosθ5inj7
Omitting the second-order minute term as sinθΩ, θζ0 and substituting the above equation into equation (8), we get V4om KIIIB sin ”t cosθ−2
I2B cosωt sinθQO80008θ-2
I2B (cos″t cosθcosQsinθ−5
inωt sinθ5inQcosθ) (9) Tilt the third term and adjust Ω to obtain cosl7 sinθ=-si
If nQ cos θ and 1; 3 tan Ω = -tan θ θQ, then V2O-KIIIB sin ωt cos θ- has 2I2
B cost cosθcosωt sinθ−K2I
2B QO8QB1nθ(cos ωt cosθ tens
in 61t sin θ) = KIIIE s, in
ωt cos θ− 2 BCO 6 Ω cos θ cos ω
t sinθ−K2I2B co8Ωsinθcos(
If we adjust I□ using the formula ωt-θ)011θD so that 1-work BI31 becomes 2-work 2BcO8Qcosθ, then V4o=KIIIB (sinωt cosθ-co
s co t sin θ)-K I BaosQ 5i
neaos(ttit-θ) 2 = KIIIB sin (ωt-θ)-to 2 engineering 2Bc
osQs1necos(ωt-θ)3 From equation (b), IC2I2B cosl) = W Substitute this into equation a3 to get V2O-KII□B sin (ωt-θ) -KtI
IB a cos (ω to # of -□I, efi) ding" KII□B77 stone f7 10 in (ωt-θ) cos & -cos (ωt-θ
) sine) (5) Considering the same as in 2, the DC output Voo becomes as shown in the following equation.

θ or θ VOO=-TF-VS αThe DC output Voo is compared to the output of equation (5), and an output with zero shifted by the angle θ where the two Hall elements are deviated from the right angle is obtained. .

That is, the phase adjustment circuit 6 performs adjustment to satisfy the
If the current adjustment circuit 5 performs adjustment that satisfies equation (b), an angle converter without nonlinear errors can be realized.

An example of the above specific adjustment method is shown below.

(1) Cancel the unbalanced voltage so that the output becomes 0 when the magnetic flux density is 0.

(3) Regarding the Hall element 3, (5-1) Adjust the Hall element 3 so that it is parallel to the magnetic flux, and adjust the angle so that the exit angle is V÷0.

(!1-2) Rotate the Hall element 3 exactly 90 degrees so that the magnetic flux hits the Hall element 3 at right angles.

(S-3) Measure the amplitude with an AC voltmeter. If this amplitude is V, make the Hall element 2 parallel to the magnetic flux and adjust the angle so that the output V□o = 0. . ((
From formula 6), θ = 90') (5) From item (2) above, Ω
=, O, θ-90° from term (4), so in equation (9), V4o= -K2I2B cosθcosω, measure the amplitude of the output of the above equation, and set this amplitude as y2, then y2= Subtracting θ from the equation (7)6→, the phase of the phase adjustment circuit 6 is adjusted as Q-1θ.

(8) Rotate Hall element 2 exactly 90 degrees and input θ=0.

v1o=KIIIB sinωt (9) Adjust the current of the current adjustment circuit 5 to KIIIB
= v2(cosθ)2.

In the above-mentioned embodiment, the phase difference detection means 8 uses the comparators 81 and 82, the flip-flop circuit 83, and the flat circuit, but the present invention is not limited to this. AND
A circuit may also be provided, in short, the phase difference is ttl.
It's fine as long as it's possible.

As explained above, according to the present invention, it is possible to realize an angle converter that has good linearity characteristics, can obtain a wide measurable range of input angle from 0 to 360 degrees, and is easy to assemble and adjust. I can do it.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the principle of an angle converter using a Hall element that has been commonly used in the past, Fig. 2 is an explanatory diagram of the configuration of an embodiment of the present invention, and Fig. 3 is an electrical diagram of the embodiment of the invention shown in Fig. 2. The circuit block diagrams in FIG. 4 and FIG. 5 are explanatory diagrams of the operation of the embodiment shown in FIG. 1...Magnetic circuit, 11.12...Permanent magnet, 13.
...Yoke, 2.3...Hall element, 4...
AC power supply circuit, 41→S phaser, 5... Current fine adjustment circuit, 6... Phase fine adjustment circuit, 7... Addition circuit, 8... Phase difference detection means, 8
1.82...Comparator, 83...Flip-flop circuit, 84...Smoothing circuit, 9...Output terminal, 0
...Input saw shaft, θ...Input rotational displacement, B...Magnetic flux density.

Claims (1)

[Claims] Two Hall elements are arranged perpendicularly to each other around an input shaft to which a rotational displacement is applied, and a common magnetic flux density is applied to the Hall elements, and a magnetic flux is generated around the input shaft in accordance with the input rotation angle. a magnetic circuit configured such that the direction of the magnetic circuit rotates relative to the Hall element; and an AC power supply circuit that applies an AC voltage having a phase difference of 90 degrees to each Hall element. a current fine adjustment circuit provided between the AC power supply circuit and one of the Hall elements; a phase fine adjustment circuit provided between the AC power supply circuit and the other of the Hall elements; An angle converter comprising: an adding circuit that adds the output voltages of the Hall elements; and a phase difference detection means that detects a phase difference between the output of the adding circuit and one of the outputs of the AC power supply circuit.