JPS59125005A - Angle converter - Google Patents

Abstract

PURPOSE:To improve a linearity characteristic so that such a wide measurable range as an input angle is ''0''-360 degrees can be obtained by applying the voltages having a phase difference of 90 degrees to each other, to each of two Hall elements, and obtaining an output voltage being directly proportional to an input angle. CONSTITUTION:Voltage of V1=Vsinomegat is applied to a Hall element 3 from an oscillating circuit 5, and a current of I1sinomegat is made to flow. Voltage V11= Vcosomegat passing through a phase shifter 6 is applied to a Hall element 4 and a current of I2cosomegat is made to flow. When an input angle theta is given to an input shaft 0, a magnetic flux density applied to the Hall elements 3, 4 becomes Bcostheta and Bsintheta, respectively, in case a magnetic flux density in the vicinity of the center of a magnetic circuit is denoted as B. Outputs of comparators 81, 82 of a difference V4 of both outputs of output voltages V2, V3 of the Hall elements 3, 4, and V1 voltage are provided to a flip-flop circuit 83. A DC output V0 is obtained through a smoothing circuit 84, but this output becomes an output voltage proportional to the input angle theta.

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 angle conversion B% using a conventionally commonly used Hall element.

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 0 perpendicular to the plane of the paper in accordance with the input angle θ.

In the above configuration, when the Hall element 2 rotates by θ angle according to the input angle 0, the voltage '%ip generated in the Hall element 2 is (1) Vr) = KBI sin 9 where: Product sensitivity of the Hall element (Input current 1mA.

Magnetic flux severity 1. Output voltage mV at kG) B: Magnetic flux density, Hall drive current θ: Input angle.

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

However, since an output proportional to the input angle θ is generally required, the output must be linearized or a small angle must be made measurable.

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 object of the present invention is to provide two holes arranged perpendicularly to each other around an input shaft to which a rotational displacement is applied. a magnetic circuit configured such that a common magnetic flux density is applied to the Hall element and the direction of the magnetic flux rotates relative to the Hall element around an axis in response to an input rotation angle; a power supply circuit that applies voltages having a phase difference of 90 degrees to each element;
An angle converter comprising an adder circuit that adds the output voltages of two Hall elements, and phase difference detection means that detects a phase difference between the output of the adder circuit and one of the outputs of the power supply circuit. The purpose of the present invention is to provide an angle converter that can obtain an output voltage that is directly proportional to the input angle, has good linearity characteristics, and can obtain a wide measurable range of input angles from 0 to 360 degrees.

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

In the figure, reference numeral 1a denotes 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. A 3 or 4-hole element arranged between permanent magnets 11 and 12,
They are arranged orthogonal to each other with axis 0 as the center, and input rotational displacement θ is input to axis 0. Thus, approximately the same magnetic flux density B is applied to the Hall elements 3 and 4. FIG. 3 shows a block diagram of the electrical circuit of FIG. 2. Reference numeral 5 denotes an oscillation circuit for AC driving the Hall elements 3 and 4, which not only drives the Hall element 3 but also applies to the Hall element 4 through a phase shifter 6 an AC voltage with a phase shift of 90 degrees.

7 is an adder circuit that adds the outputs of the Hall elements 3.4, and in this case, the difference between the two outputs is calculated.

8 is a phase difference detection means, in this case, a comparator 8
1.82, a flip-flop circuit 83 and a smoothing circuit 84. The output of the adder circuit 7 is connected to the SET side of the flip-flop circuit 83 via a comparator 81.
The output of the oscillation circuit 5 is connected to the RESET side of the Noritsu flop circuit 83 via a comparator 82. The p side of the FRI, PFLO, P circuit 83 is connected to the output terminal 9 via a smoothing circuit 84.

In the above configuration, a voltage of V□=V sin Ql t is applied from the oscillation circuit 5 to the Hall element 3,
A current of 11 sin 6 At is applied. A voltage V11=V cos ωt passed through the phase shifter 6 is applied to the Hall element 4, and a current of 12 coszr t flows therethrough. When the input angle O to the input shaft 0 is fl-0, as shown in FIG. 4, if the Hall element 3 receives the magnetic flux at right angles, then four Hall elements receive the magnetic flux in parallel. Input angle 0 on input axis 0
, the magnetic flux densities applied to the Hall elements 3 and 4 become B cos θ and Bs1n θ , respectively, where B is the magnetic flux density near the center of the magnetic circuit. The product sensitivity of Hall elements 3 and 4 is 1. 2, the output voltage of Hall elements 3 and 4 v2. v3 becomes. When the difference between the outputs v2 and v3 is taken by the adder circuit 7, KII
IB ”K2I,;,B, the difference between both outputs V
4 HaV4=KIIIB sin (ωt-θ)(4
). The waveforms of the v4 and v1 voltages are shown in FIG. 5 (4).

(2) When the voltage is passed through the comparator 81, a waveform as shown in FIG. 5(C) is obtained; on the other hand, when the v1 voltage is passed through the comparator 82, a waveform as shown in FIG. 5(CB) is obtained. When the outputs of the comparators 81 and 82 are applied to the Noritsubu flop circuit 83, the p-side output 1d has a waveform as shown in FIG. 5(d). This output can be passed through a smoothing circuit 84 to obtain a DC output Vo. DC output is as shown in the zero-order equation.

here T: period TI’ Pulse width ■s: amplitude Therefore, the output voltage V is proportional to the input angle 0.

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 0 oscillation frequency do not affect measurement accuracy. ■
The input angle 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.

In the above-mentioned embodiment, the phase difference detecting means 8 includes the comparators 81 and 82, the flip-flop circuit 83, and the smoothing circuit, but is not limited thereto, AND instead
A device provided with a circuit may be used, and in short, any device that can detect a phase difference may be used.

As described above, according to the present invention, it is possible to provide a sharp angle converter that has good linearity characteristics and a wide measurable input angle range of 0 to 360 degrees.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the principle of an angle converter using a conventionally commonly used Hall element, Fig. 2 is an explanatory diagram of the configuration of an embodiment of the present invention, and Fig. 5 is an explanatory diagram of the configuration of an embodiment of the present invention. Block diagram of the electric circuit, Figure 4. FIG. 5 is an explanatory diagram of the operation of the embodiment shown in FIG. 1a...Magnetic circuit, 11.12...Permanent magnet, 13
...Yoke, 3.4...Hall element, 5...
・Oscillation circuit, 6... Phase shifter, 7... Addition circuit, 8.
...Phase difference detection means, 8 pieces. 82... Comparator, 83... Flip flow,
F circuit, 84... Smoothing circuit, 9... Output terminal, 0.
・Input shaft, θ...Input rotational displacement, B...Magnetic flux density. M1 Figure F M4 Figure Leather 5 Figure (C) @ Knee

Claims (1)

[Claims] Two holes are arranged perpendicularly to each other around the input shaft to which a rotational displacement is applied; a magnetic circuit configured such that the direction of magnetic flux rotates relative to the Hall element;
an oscillation circuit that applies alternating current voltages having a phase difference of 90 degrees to each of the hall elements, an adder circuit that adds the output voltages of the two hall elements, and an output of the adder circuit and the power supply. An angle converter comprising phase difference detection means for detecting a phase difference with one of the outputs of the circuit.