JPH0349043B2 - - Google Patents

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 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 θ, the voltage V〓 generated in the Hall element 2 is V〓=KBIsinθ (1) where K: Product sensitivity of the Hall element (input current 1mA ,
Output voltage (mA per 1 kg of magnetic flux density) B: Magnetic flux density I: Hall drive current θ: Input angle.

As a result, the output voltage V〓 is proportional to the sine of 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 purpose of the present invention is to have good linearity characteristics, obtain a wide measurable range of input angle from 0 to ∞ degrees,
An object of the present invention is to provide an angle converter whose zero position can be arbitrarily selected.

To achieve this purpose, two Hall elements are arranged orthogonally to each other around the input axis to which the rotational displacement is applied, and a common magnetic flux density is applied to the Hall elements to correspond to the input rotation angle. a magnetic circuit configured such that the direction of magnetic flux rotates relative to the Hall element around the input shaft;
An alternating current voltage having a phase difference of 90 degrees is applied to each of the Hall elements. an AC power supply circuit; a first addition circuit that adds the output voltages of the two Hall elements; a first counter that integrates the output frequencies of the first addition circuit; and a first counter that adds up the output frequencies of the AC power supply circuit. 2 counters and the second counter.
The angle converter includes a second addition circuit that calculates the difference between the integrated values of a counter and the first counter, and an integrator that integrates the output of the second addition circuit.

Examples will be described below.

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

In the figure, 1 _a is a magnetic circuit, and permanent magnet 11
_a , _12a and a yoke _13a . Permanent magnet 11
_a and _12a are attached to both ends of a U-shaped yoke _13a , and are arranged so that a magnetic field is generated between the permanent magnets _11a and _12a . 3 and 4 are Hall elements arranged between permanent magnets 11 _a and 12 _a ,
They are arranged perpendicularly to each other around axis 0, and
The input rotational displacement θ is input to . Therefore, the Hall elements 3 and 4 have approximately the same magnetic flux density B.
is added. FIG. 3 shows a block diagram of the electrical circuit of FIG. Reference numeral 5 designates an AC power supply circuit that drives the Hall elements 3 and 4 with alternating current.
Apply 90 degree out-of-phase alternating current voltages through the
A first adding circuit 7 adds the outputs of the Hall elements 3 and 4, and in this case, the difference between the two outputs is calculated. 8 is a first counter that integrates the output frequency of the first adder circuit 7. Reference numeral 9 denotes a second counter that integrates the output frequency of the AC power supply circuit 5. 1
0 is a second addition circuit that calculates the difference between the integrated values of the first counter 8 and the second counter 9. Reference numeral 11 denotes an integrator that integrates the output of the second adder circuit. 1
Reference numeral 2 denotes a calculation display that calculates and displays the output of the integrator 11. 13 is a timing generator connected to the first counter 8, the second counter 9, the second addition circuit 10, and the integrator 11.

In the above configuration, a voltage of V ₁ =Vsinωt is applied from the AC power supply circuit 5 to the Hall element 3,
A current of Ilsinωt flows. A voltage V ₁₁ =Vcosωt is applied to the Hall element 4 through the phase shifter 6.
A current of I ₂ cosωt flows. When the input angle θ to the input shaft 0 is θ=0, as shown in FIG. 4, if the Hall element 3 receives the magnetic flux at right angles, the Hall element 4 receives the magnetic flux in parallel. Input angle 0
When an input angle θ is given to
becomes. The product sensitivity of Hall elements 3 and 4 is K ₁ ,
If K ₂ , the output voltages V ₂ and V ₃ of Hall elements 3 and 4 are V ₂ =K ₁ I ₁ Bsinωt・cosθ=K ₁ I ₁ B{1/2sin
(ωt+θ)+1/2sin(ωt+θ)}(2) V ₃ =K ₂ I ₂ Bcosωt・sinθ=K ₂ I ₂ B{1/2sin
(ωt+θ)−1/2sin(ωt−θ)}(3). If we take the difference between the outputs V ₂ and V ₃ using the adder circuit 7, then if K ₁ I ₁ B = K ₂ I ₂ B, then the difference between the two outputs V ₄
becomes V ₄ = K ₁ I ₁ Bsin (ωt−θ) (4). The waveforms of the V ₄ and V ₁ voltages are shown in FIG.

Here, the first counter 8, the second counter 9
The frequencies f ₄ , f ₁ of the voltages V ₄ , V ₁ input to are as follows: f ₄ =(ω−dθ/dt)/2 (5) f ₁ =ω/2π (6).

Here, when the difference between f ₁ and f ₄ is integrated, ∫(f ₁ −f ₂ )dt=∫dθ/dtdt=∫dθ=θ (7).

Specifically, the output frequencies f ₁ and f ₄ are output by the first counter 8, the second counter 9, and the timing generator 1.
3 for a certain period of time, and the final values A and A' are calculated in the second adder circuit 10, as shown in FIG. When this value is integrated by the integrator 11, a value proportional to the input angle θ is obtained.

As a result, the circuit configuration can be made up of digital circuits and a digital output can be obtained directly, making it easy to connect to a computer or the like. The measurement range is 0
It can measure angles up to ~∞. Resetting for the incremental system is easy, and the zero position can be arbitrarily selected.

Note that, of course, the calculation display 12 may not be provided.

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 angles from 0 to ∞, and can arbitrarily select the zero position.

[Brief explanation of drawings]

Figure 1 is a diagram explaining 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 one embodiment of the present invention, FIG. 3 is a block diagram of the electric circuit of the embodiment of FIG. 2, and FIGS. 4 to 6 are diagrams of operation of the embodiment of FIG. 2. . 1 _a ...Magnetic circuit, 11 _a , 12 _a ...Permanent magnet,
13 _a ... Yoke, 3, 4... Hall element,
5... AC power supply circuit, 6... Phase shifter, 7... First
Addition circuit, 8...First counter, 9...Second counter, 10...Second addition circuit, 11...Integrator, 12...Arithmetic display, 13...Timing generator.

Claims (1)

[Claims] 1. Two Hall elements arranged perpendicularly to each other around an input shaft to which rotational displacement is applied, and a common magnetic flux density is applied to the Hall elements, and A magnetic circuit configured such that the direction of magnetic flux rotates relative to the Hall element, and an AC voltage having a phase difference of 90 degrees between the Hall elements are applied to each Hall element. an AC power supply circuit; a first addition circuit for adding the output voltages of the two Hall elements;
A first counter that integrates the output frequency of the adder circuit, a second counter that integrates the output frequency of the AC power supply circuit, and a second adder circuit that calculates the difference between the integrated values of the second counter and the first counter. and an integrator that integrates the output of the second addition circuit.