JPH0229166B2 - KAKUDOHENKANKI - 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 Vθ generated in the Hall element 2 is V = KBI sinθ (1) where K: Product sensitivity of the Hall element (input current 1 mA , output voltage mV per 1kG of magnetic 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.

An object of the present invention is to provide two Hall elements 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 to move the shaft in accordance with the input rotation angle. A magnetic circuit configured so that the direction of magnetic flux rotates relative to the Hall element at the center, a power supply circuit that applies voltages to each Hall element with a phase difference of 90 degrees from each other, and two The input angle The purpose of the present invention is to provide an angle converter that has good linearity characteristics and can provide 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, 1a is a magnetic circuit, and permanent magnet 1
1, 12 and a yoke 13. permanent magnet 11,
12 are attached to both ends of a U-shaped yoke 13, and are arranged so that a magnetic field is generated between the permanent magnets 11 and 12. 3 and 4 are hall elements,
It is arranged between the permanent magnets 11 and 12, and arranged orthogonal to each other with axis 0 as the center, and input rotational displacement θ is input to axis 0. Thus, substantially equal 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. 5 is an oscillation circuit that drives the Hall elements 3 and 4 with alternating current.
Apply alternating current voltages that are 90 degrees out of phase. 7 is an adder circuit that adds the outputs of Hall elements 3 and 4;
In this case, the difference between both 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 sent to the flip-flop circuit 83 via a comparator 81.
The output of the oscillation circuit 5 is connected to the SET side, and the output of the oscillation circuit 5 is connected to the flip-flop circuit 8 via the comparator 82.
Connected to the RESET side of 3. The flip-flop circuit 83 side is connected to the output terminal 9 via a smoothing circuit 84.

In the above configuration, a voltage of V ₁ =Vsinωt is applied from the oscillation circuit 5 to the Hall element 3, and I ₁ sinωt
A current flows through the current. Hall element 4 has a phase shifter 6
A voltage V ₁₁ =Vcosωt is applied to the current I ₂ cosωt. 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 θ to input axis 0
is given, the magnetic flux density applied to the Hall elements 3 and 4 changes the magnetic flux density near the center of the magnetic circuit to B
Then, they become Bcosθ and Bsinθ, respectively. If the product sensitivity of Hall elements 3 and 4 is K ₁ and K ₂ ,
The output voltages V ₂ and V ₃ of the Hall elements 3 and 4 are V ₂ = K ₁ I ₁ B sinωt・cos θ = K ₁ I ₁ B {1/2 sin (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. 5A.

When V ₄ voltage is passed through comparator 81, Figure 5C
On the other hand, when the V ₁ voltage is passed through the comparator 82, a waveform as shown in FIG. 5B is obtained. When the outputs of the comparators 81 and 82 are applied to the flip-flop circuit 83, the output has a waveform as shown in FIG. 5d. Smoothing circuit 8
DC output Vo can be obtained through 4. The DC output Vo is as shown in the following equation.

Vo=T ₁ /TVs=θ/ω/2π/ωVs=θ/2πVs (5) Here, T: Period T ₁ : Pulse width Vs: Amplitude Therefore, the output voltage is proportional to the input angle θ
Vo 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.

Note that if the comparators 81 and 82 are configured with zero-crossing detectors, it is possible to obtain a device in which fluctuations in the oscillation amplitude do not cause errors.

In the above embodiment, the phase difference detection means 8 is composed of comparators 81, 82, a flip-flop circuit 83, and a smoothing circuit, but it is not limited to this. For example, an AND circuit may be used instead of the flip-flop circuit. In short, it is sufficient if the phase difference can be detected.

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

[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 FIG.
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, 81, 82...Comparator, 83...Flip-flop circuit, 84
... Smoothing circuit, 9 ... Output terminal, 0 ... Input shaft,
θ...Input rotational displacement, B...Magnetic flux density.

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 oscillation circuit that applies alternating current voltages having a phase difference of 90 degrees to each Hall element; An angle converter comprising: an adder circuit that adds the output voltages of the two Hall elements; and a phase difference detector that detects a phase difference between the output of the adder circuit and one of the outputs of the power supply circuit.