JPH0510708A - Position detector - Google Patents

Abstract

PURPOSE:To provide a position detector at which a linear sphere usable for position detection is made wide. CONSTITUTION:At a rotation position detector, a transducer 1 having magnetic resistance elements 11, 12, 13 generating output voltages V11, V12, V13 that are according to the rotation positions of permanent magnets and the permanent magnets rotating at positions opposite to the magnetic resistance elements 11, 12, 13 are equipped. In addition, an operation circuit 3 which superimposes output voltages V12, V13 that are correction signals on the output voltage V11 that is a basic signal, and realizes linearization between the minimum and maximum of the output voltage V11, is equipped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact type position detecting device.

[0002]

2. Description of the Related Art As shown in FIG.
There is known a position detecting device that is placed in a magnetic field 420 that rotates around a center 421 to obtain the rotational positions of the magnetic element 400 and the magnet.

[0003]

However, the linearity ± 3
The linear area indicating% F, S is approximately 70 ° when the magnetic element 400 is a Hall element and approximately 35 ° when the magnetic element 400 is a magnetoresistive element, and the above-mentioned conventional position detection in which the position is detected in the linear area is shown. The device has a problem that the position detection range is narrow. An object of the present invention is to provide a position detection device in which a linear area that can be used for position detection is widened.

[0004]

[Means for Solving the Problems] In order to solve the above problems,
The present invention has a magnetic element that receives a change in magnetic field strength, and a transducer that converts the magnetic field strength into an electric signal,
A magnet disposed at a position facing the magnetic element and a rotating member that rotates one of the transducer and the magnet are provided, and a relative rotational position between the transducer and the magnet is determined based on an electric signal from the transducer. In the position detecting device for detecting, the transducer is a basic signal magnetic element for generating a basic signal having a size corresponding to the relative rotational position, and a correction having a size corresponding to the relative rotational position for correcting the basic signal. A magnetic signal shaping magnetic element for generating a signal is provided, and the correction signal is superimposed on the basic signal to provide a waveform shaping means for linearizing the minimum and maximum of the basic signal.

[0005]

When the transducer or the magnet is rotated by the rotating member, the basic signal magnetic element produces a basic signal which changes in a wave shape in accordance with the relative rotational position of the transducer and the magnet, and the correction signal magnetic element is A correction signal that changes in a wave shape according to the relative rotational position is generated. The waveform shaping means superimposes the correction signal on the basic signal to minimize the basic signal.
Linearize the waveform between maxima.

[0006]

Since the waveform between the minimum and maximum of the basic signal is linearized, the linear region that can be used to detect the relative rotational position between the transducer and the magnet is widened.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. As shown in FIGS. 1 and 2, the rotational position detecting device includes magnetoresistive elements 11, 12, and 13 (thin film Ni-C).
Transducer 1 having a (ferromagnetic alloy), and a permanent magnet 2 located opposite to the magnetoresistive elements 11, 12, and 13.
A computing circuit 3 and a rotor 4 for rotating the permanent magnet 2.

The transducer 1 includes magnetoresistive elements 11, 12 and 13 whose electric resistance values increase and decrease due to a change in the interlinking angle θ between the element short-side direction and the magnetic field direction, and the resistance value change of these elements as a voltage change. And a constant current source 14 for taking out. The magnetoresistive element 11 is a basic signal magnetic element, and as shown in FIG. 3, is formed into a comb shape on the insulating substrate 110 fixed to the substrate mounting member 100 by vapor deposition and photoetching techniques (similar to other elements). (Twice the number of turns)
And an output voltage V ₁₁ having a magnitude corresponding to the rotational position of the permanent magnet 2 is generated. The magnetoresistive element 12 is a magnetic element for correction signal, has a length in the longitudinal direction slightly shorter than that of the magnetoresistive element 11, and is filmed in parallel with the magnetoresistive element 11 in a comb shape (the number of folding is once). ing. The magnetoresistive element 13 is a magnetic element for a correction signal, has a length in the longitudinal direction slightly shorter than that of the magnetoresistive element 12, and forms an angle of 45 ° with the magnetoresistive elements 11 and 12, and has a comb shape (the number of folding times is Once). Here, the folding back of each of the magnetoresistive elements 11 to 13 is not limited to the above number.

The permanent magnet 2 (rectangular columnar shape) is fixed to the center of the upper portion of the rotor 4 pivotally mounted on the housing (non-magnetic body) 200 in the figure and is filled with a parallel uniform magnetic field. The parallel state is maintained and the rotor 4 rotates together. The permanent magnet 2 is a strong magnet such that the strength of the rotating magnetic field acting on the magnetoresistive elements 11, 12, 13 located at a distance 21 is equal to or higher than the saturation magnetic field of the magnetoresistive elements 11, 12, 13. Is.

The arithmetic circuit 3 includes an operational amplifier 301 and a resistor 3.
02, 303, output voltage V ₁₁Amplifies
Output signal V '₁₁And a buffer amplifier circuit 30 for obtaining
Output voltage V with 311 and 312₁₂, V₁₃The central value of
An offset adjustment unit 31 for constant adjustment, an FET 321,
The resistors 322 and 323 and the operational amplifier 324 are provided so that the phases are the same.
Output voltage V differing by 45 °₁₂, V₁₃Half cycle by multiplying by
Half-cycle generating section 32 for converting into a waveform of
Half cycle with 32, 333, 334 and operational amplifier 335
Correction signal Vh and output signal V ′₁₁And add
Output signal V _outAnd an adding unit 33 that outputs

Next, the operation of the rotational position detecting device will be described. When the rotor 4 rotates, the positional relationship between the permanent magnet 2 and the magnetoresistive elements 11, 12, 13 changes, and the magnetic field strength received by the magnetoresistive elements 11, 12, 13 changes. Output voltages V ₁₁ , V ₁₂ , and V ₁₃ represented by the following equations are generated at both ends of the magnetoresistive elements 11, ₁₂ , and ₁₃ . However, R ₁₁ ,
R ₁₂ and R ₁₃ are resistance values of the magnetoresistive elements 11, ₁₂ , and ₁₃ ,
θ is the interlinking angle between the lateral direction and the magnetic field direction of each of the magnetoresistive elements 11, 12, and 13, I is the constant current flowing from the constant current source 14 to each of the magnetoresistive elements 11, 12, and 13, (‖), ( ⊥) indicates the positional relationship between the longitudinal direction (current flowing direction) of each of the magnetoresistive elements 11, 12, 13 and the magnetic field direction. However,
(‖) And (⊥) indicate that the positional relationships are parallel and vertical, respectively. V ₁₁ = R ₁₁ (⊥) ・ SIN ² θ + R ₁₁ (‖) ・ COS ²
θ = A ₁₁ · COS 2 θ + B ₁₁ A ₁₁ = [{R ₁₁ (‖) -R ₁₁ (⊥)} / 2] × I B ₁₁ = [{R ₁₁ (‖) + R ₁₁ (⊥)} / 2] × IV ₁₂ = R ₁₂ (⊥) ・ SIN ² θ + R ₁₂ (‖) ・ COS ²
θ = A ₁₂ · COS 2 θ + B ₁₂ A ₁₂ = [{R ₁₂ (‖) -R ₁₂ (⊥)} / 2] × I B ₁₂ = [{R ₁₂ (‖) + R ₁₂ (⊥)} / 2] × IV ₁₃ = R ₁₃ (‖) · SIN ² (θ−45 °) + R ₁₃ (⊥) · COS ² (θ−45 °) = A ₁₃ · COS ² (θ−45 °) + B ₁₃ Note that A ₁₃ = [{R ₁₃ (‖) -R ₁₃ (⊥)} / 2] × I B ₁₃ = [{R ₁₃ (‖) + R ₁₃ (⊥)} / 2] × I The offset adjustment unit 31 is an AC signal only. Since it is composed of passing capacitors 311, 312, the real constants B ₁₂ , B
₁₃ becomes zero, the voltage V _'12 drains the FET321 half cycle generation unit 32, to the gate of the following formula,
V _'13 is applied. V ′ ₁₂ = A ₁₂ · COS 2 θ V ′ ₁₃ = A ₁₃ · COS 2 (θ−45 °) The half-cycle generator 32 multiplies the voltage V ′ ₁₂ and the voltage V ′ ₁₃ by a half represented by the following formula. A cycle correction signal Vh is obtained. Vh = A ₁₂ · COS 2 θ × A ₁₃ · COS 2 (θ-45
_{°) = A 12 · A 13} /2 × SIN4θ addition section 33, the output signal V _'11 and the correction signal and Vh are synthesized and output signal V which attained linearization between minimum-maximum of the following formula Output _out . _{V out = V 11 + Vh =} (A 11 · COS2θ + B 11) + (A 12 · A 13/2) ×
SIN4θ

Next, the function and effect of the rotational position detecting device will be described. (A) The output signal V _out is linearized between the minimum and maximum as shown in FIG. 4, and the linear region showing the linearity ± 3% F, S is expanded from the conventional 35 ° to 90 ° or more. did. (B) is a configuration for generating a correction signal Vh using the output voltage V ₁₃ of the magnetoresistive element 13 shifted output voltage V _12, and 45 ° phase of the magnetoresistive element 11 in phase magnetoresistive element 12 of Therefore, the arithmetic circuit 3 can be simple. (C) Since the magnetic resistance elements 11, 12 and 13 are fixed and the permanent magnet 2 is rotated, the output voltage V ₁₁ ,
Excellent processability for V ₁₂ and V ₁₃ . (D) Since the magnetoresistive elements 11, 12 and 13 operate in a saturated magnetic field, they are not affected by changes in magnetic field strength unrelated to the interlinkage angle θ and position variations other than the rotation direction.

The present invention includes the following embodiments in addition to the above embodiments. a. In order to concentrate and equalize the magnetic flux, as shown in FIG. 5, the permanent magnet 2 and the magnetic material arm portions 22 and 2 for forming the magnetic path are formed.
3 may be provided. b. The magnetic element also includes a Hall element in the present specification. c. The magnetic element may be arranged on the rotating side and the magnet may be fixed. In this case, it is necessary to connect the waveform shaping means with a brush or the like. d. The magnet may be a disk-shaped permanent magnet. It may also be an electromagnet. When the rotating side is an electromagnet, it is necessary to supply power with a brush or the like. e. A constant voltage source may be incorporated in the transducer to convert a change in magnetic field strength into a change in current.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram of a rotational position detecting device according to an embodiment of the present invention.

FIG. 2 is a structural explanatory view of a rotational position detecting device according to an embodiment of the present invention.

FIG. 3A is an explanatory diagram showing a formation state of magnetoresistive elements in the apparatus, and FIG. 3B is a diagram showing changes in resistance values of the elements.

FIG. 4 is a graph showing an output voltage V ₁₁ and an output signal V _out .

FIG. 5 is a structural explanatory view of a rotational position detecting device according to another embodiment of the present invention.

6 (a) to 6 (c) are views for explaining a conventional technique, FIG. 6 (a) is an explanatory view showing a magnetic element placed in a rotating magnetic field, and FIG. 6 (b) is a magnetic element. Is a Hall element, a graph showing the relationship between the interlinkage angle θ ′ and the Hall element output, and (c) shows the relationship between the interlinkage angle θ and the magnetoresistive element output when the magnetic element is a magnetoresistive element. It is a graph shown.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Transducer 2 Permanent magnet (magnet) 3 Calculation circuit (waveform shaping means) 4 Rotor (rotating member) 11 Magnetoresistive element (magnetic element for basic signal) 12, 13 Magnetoresistive element (magnetic element for correction signal) V ₁₁ Output voltage (Basic signal) V ₁₂ , V ₁₃ output voltage (correction signal)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiko Miyahara 1-1, Showa-cho, Kariya city, Aichi Nihon Denso Co., Ltd.

Claims (1)

Claim: What is claimed is: 1. A transducer having a magnetic element that receives a change in magnetic field strength, converting the magnetic field strength into an electric signal, a magnet arranged at a position facing the magnetic element, A position detection device that includes a rotating member that rotates one of a transducer and a magnet, and detects a relative rotational position between the transducer and the magnet based on an electric signal from the transducer, wherein the transducer is the relative rotational position. A basic signal magnetic element that generates a basic signal having a magnitude corresponding to the correction signal, and a correction signal magnetic element that corrects the basic signal and that generates a correction signal having a magnitude corresponding to the relative rotational position. A position characterized by including a waveform shaping means for superimposing a signal on the basic signal to linearize the minimum and maximum of the basic signal. Detection device.