KR20040010258A - Magnetic detection apparatus - Google Patents

Abstract

PURPOSE: A magnetism detection device is provided to detect magnetism regardless of a gap by forming a small interval between adjacent tooth parts and a small width in the circumferential direction of the tooth parts themselves. CONSTITUTION: In the device, the magnetic detection apparatus according to the first embodiment includes a processing circuit(2) being arranged apart from a magnetic moving member(1) on a plane thereof, which is formed on its periphery with convex portions in the form of teeth(1a) and rotates around an axis of rotation or rotation shaft(4) in a circumferential direction, and having a bridge circuit comprising a first magnetoresistive segment(2a) and a second magnetoresistive segment(2b), which act as magnetoelectric conversion elements, a magnet(3) for applying a magnetic field to the first and second magnetoresistive segments(2a,2b) as well as applying a magnetic field to the magnetic moving member(1) in a direction of the axis of rotation thereof, and a magnetic guide(5) of a magnetic material arranged between the processing circuit(2) and the magnet(3) for preventing dispersion of a magnetic flux from the magnet(3). The magnetic guide(5) has a pair of projected members(5a,5b) arranged in a circumferentially spaced and opposed relation with respect to each other.

Description

Magnetic Detection Device {MAGNETIC DETECTION APPARATUS}

The present invention relates to, for example, a magnetic detection device for detecting a rotational position of a magnetic body rotating in a circumferential direction with a tooth formed at a peripheral edge thereof.

Fig. 13A is a perspective view of a conventional magnetic detection device, Fig. 13B is a partial plan view of the magnetic detection device of Fig. 13A, Fig. 14 is an electric circuit diagram of a conventional magnetic detection device, and Fig. 15 is a magnetic The operation waveform diagram of a detection apparatus.

The magnetic detecting device is a magnetoelectric conversion element which is formed away from the magnetic body 1 on the plane of the magnetic body 1 in which the teeth 1a are formed at the periphery and rotate about the rotation axis 4 in the circumferential direction. The magnetic field is applied to the processing circuit section 20 having the bridge circuit by the magnetoresistive segment 2a and the fixed resistor 12b and the bridge circuit by the fixed resistor 12c and the fixed resistor 12d, and the magnetic resistance segment 2a. It is provided with a magnet (3) for applying the magnetic field to the magnetic movable body (1) in the direction of the rotation axis of the magnetic movable body (1).

In addition, the circuit processing unit 20 includes a differential amplifier circuit 13, a comparison circuit 14, and an output circuit 15 for amplifying a signal whose voltage is changed by a change in the resistance value of the magnetoresistive segment 2a.

In the magnetism detecting device having the above-described configuration, the rotational shaft 4 rotates so that the magnetic movable body 1 also rotates in synchronization and the magnetic field from the magnet 3 applied to the magnetoresistive segment 2a changes.

As a result, as shown in FIG. 15, the resistance value of the magnetoresistive segment 2a changes when the magnetic body 1a opposes the magnetoresistive segment 2a and when it opposes the groove portion 1b. The output from the amplifier circuit 13 also changes. Finally, waveforms are output from the output terminal 16 of the processing circuit section 20 by differential amplifier circuits, and correspond to "1" or "0" corresponding to the teeth 1a and 1b of the magnetic moving body 1. Final output signal is obtained.

By the way, as shown to Fig.16 (a), (b), the space | interval between adjacent tooth parts 1a and the width | variety of the main direction of the tooth part 1a itself are narrow, and the main surface of the magnetic body 1 and magnetic When the distance between the resistor segments 2a in the opposite direction (hereinafter referred to as GAP) is large, the final output signal of "1" or "0" from the output terminal 16 of the processing circuit section 20 as shown in FIG. There was a problem that a case could not be obtained.

The present invention aims to solve the above problems, and the magnetic detection device capable of detecting the rotational position of the magnetic body even when the gap between adjacent teeth and the width of the main direction of the teeth itself is small and the GAP is large. The purpose is to get.

The magnetic detecting device according to the present invention has a convex portion formed at the edge thereof and is disposed away from the magnetic body on the plane of the moving magnetic body, and has a bridge circuit by the first and second magnetoelectric conversion elements. And a magnet for applying a magnetic field to the first and second magnetoelectric conversion elements, while applying a magnetic field in a direction perpendicular to the plane of the moving direction of the magnetic body, wherein the magnet Of the magnetoelectric conversion element is disposed on a substantially centerline of the magnet on a line facing the magnetic body when viewed in the vertical direction and is differentially output from the outputs of the first and second magnetoelectric conversion elements. To get

1A is a perspective view of a magnetic detection device of Embodiment 1 of the present invention.

Fig. 1B is a partial plan view of the magnetism detecting device of Fig. 1A, and Fig. 1C is a pattern diagram of the magnetoresistive segment of Fig. 1A.

FIG. 2 is an operational waveform diagram of the magnetic detection device of FIG. 1. FIG.

Fig. 3 (a) is a perspective view of the magnetic detection device of Embodiment 2 of the present invention, Fig. 3 (b) is a partial plan view of the magnetic detection device of Fig. 3 (a), and Fig. 3 (c) is Fig. 3 (a). Figure of pattern of magnetoresistive segment of.

4 is an operation waveform diagram of the magnetic detection device of FIG. 3.

Fig. 5 is a view in which the operation waveforms of the magnetic detection device of Embodiment 1 and the operation waveforms of the magnetic detection device of Embodiment 2 are superimposed.

6 (a) is a perspective view of the magnetic detection device of Embodiment 3 of the present invention, FIG. 6 (b) is a partial plan view of the magnetic detection device of FIG. 6 (a), and FIG. 6 (c) is FIG. The pattern diagram of the magnetoresistive segment of (a).

7 is an operation waveform diagram of the magnetic detection device of Embodiment 3;

Fig. 8 is a diagram showing the relationship between the segment pitch N and the differential amplification output MIN amplitude in the magnetic detection device of Embodiment 4 of the present invention.

Fig. 9 is a diagram showing the relationship between the pitch of the protrusions and the differential amplifier output MIN amplitude in the magnetic detection device of Embodiment 5 of the present invention.

Fig. 10 is a MR loop characteristic diagram of a GMR element in the magnetic detection device of Embodiment 6 of the present invention.

11 is an electric circuit diagram of a magnetic detection device of Embodiment 7;

12 is an operational waveform diagram of the magnetic detection device of Embodiment 7;

Fig. 13A is a perspective view of a conventional magnetic detection device, and Fig. 13B is a partial plan view of the magnetic detection device of Fig. 13A.

14 is an electric circuit diagram of the magnetic detection device of FIG.

15 is an operational waveform diagram of the magnetic detection device of FIG. 13;

Fig. 16A is a perspective view of another conventional magnetic detection device, and Fig. 16B is a partial plan view of the magnetic detection device of Fig. 16A.

17 is an operational waveform diagram of the magnetic detection device of FIG. 16;

<Description of the symbols for the main parts of the drawings>

1: Magnetic body, 1a: Tooth part,

2: processing circuit portion, 2a: first magnetoresistive segment,

2b: second magnetoresistive segment, 2c: third magnetoresistive segment,

2d: fourth magnetoresistive segment, 3: magnet,

4: rotation axis, 5: magnetic body guide,

5a: first salient pole, 5b: second salient pole,

20: differential flip flop circuit.

EMBODIMENT OF THE INVENTION Hereinafter, although embodiment of this invention is described, the same or equivalent member site | part as a conventional thing is attached | subjected and demonstrated with the same code | symbol.

Embodiment 1.

Fig. 1A is a perspective view of a magnetic detection device of Embodiment 1 of the present invention, Fig. 1B is a partial plan view of the magnetic detection device of Fig. 1A, and Fig. 1C is Fig. 1A. Is a pattern diagram of a magnetoresistive segment.

The magnetic detecting device is arranged to be separated from the magnetic body 1 on a plane of the magnetic body 1 which is formed at the periphery of the toothed part 1a, which rotates about the rotation axis 4 in the circumferential direction. A magnetic field is applied to the processing circuit section 2 having a bridge circuit composed of a magnetoresistive segment 2a and a second magnetoresistive segment 2b, which are magnetoelectric conversion elements, and magnetoresistive segments 2a and 2b. The magnetic flux from the magnet 3, which applies the magnetic field to the magnetic moving body 1 in the direction of the rotation axis of the magnetic moving body 1, and the magnet 3 provided between the processing circuit section 2 and the magnet 3, is dispersed. The magnetic body guide 5 which prevents is provided. This magnetic body guide 5 has a pair of protrusions 5a and 5b facing each other at intervals in the circumferential direction. In addition, the processing circuit unit 2 includes an automatic amplifier circuit 13, a comparison circuit 14, and an output circuit 15 for amplifying a signal whose resistance value change of the magnetoresistive segments 2a and 2b is changed to a voltage. .

This bridge circuit differs from the conventional one shown in FIG. 14 in that the second magnetoresistive segment 2b is assembled in place of the fixed resistor 12b.

The first magnetoresistive segment 2a is arranged on the side of the second salient pole portion 5b. The second magnetoresistive segment 2b is disposed on an approximately centerline of the width dimension of the magnet 3 in the circumferential direction of the magnet 3 when viewed along the rotation axis direction and on an approximately centerline between the annular protrusions 5a and 5b. It is.

In the magnetic detection device having the above-described configuration, as the rotary shaft 4 rotates, the magnetic movable body 1 also rotates in synchronization, and the magnetic field from the magnet 3 applied to the magnetoresistive segments 2a and 2b changes. As a result, as shown in FIG. 2, the magnetoresistive segment 2a is different from when the toothed portion 1a of the magnetic body 1 faces the magnetoresistive segment 2a and when it opposes the groove portion 1b. The resistance value of 변화 changes and the output from the differential amplifier circuit 13 also changes. Finally, at the output terminal 16 of the processing circuit section 2, the differential amplification circuit output is waveform shaped, corresponding to the teeth 1a and the groove 1b of the magnetic moving body 1, or " 1 " A final output signal of 0 "is obtained.

In this embodiment, as can be seen in FIG. 2, the output terminal 16 of the processing circuit section 2 also has a small gap between the adjacent teeth 1a and the width of the main direction of the teeth 1a itself and a large GAP. ), A final output signal of "1" or "0" is obtained, and the magnetic detection device improves the position detection accuracy with respect to the magnetic body 1.

Embodiment 2.

Fig. 3 (a) is a perspective view of the magnetic detection device of Embodiment 2 of the present invention, Fig. 3 (b) is a partial plan view of the magnetic detection device of Fig. 3 (a), and Fig. 3 (c) is Fig. 3 (a). Is a pattern diagram of a magnetoresistive segment.

In this embodiment, the processing circuit unit 2 again has a bridge circuit by the third magnetoelectric conversion element 2c and the fourth magnetoelectric conversion element 2d compared with that of the first embodiment.

The second magnetoresistive segment 2b and the third magnetoresistive segment 2c are each a pair of protrusions 5a on approximately the center line of the width dimension in the circumferential direction of the magnet 3 when viewed in the rotational axis direction. It is arrange | positioned on the substantially centerline between (5b). The first magnetoresistive segment 2a is arranged on the side of the second protrusion 5b, and the fourth magnetoresistive segment 2d is arranged on the side of the first protrusion 5a.

The differential amplification from the midpoint output of the first magnetoresistive segment 2a and the second magnetoresistive segment 2b and the midpoint output of the third magnetoresistive segment 2c and the fourth magnetoresistive segment 2d. To get

4 is an operation waveform diagram of the magnetic detection device of the embodiment, wherein the resistance values of the magnetoresistive segments 2a, 2b, 2c, and 2d change corresponding to the shape of the magnetic body 1, Differential amplification of the midpoint output of the first magnetoresistive segment 2a and the second magnetoresistive segment 2b and the midpoint output of the third magnetoresistive segment 2c and the fourth magnetoresistive segment 2d. An output is obtained, this differential amplified output is waveform shaped, and the final output signal "1" or "0" corresponding to the shape of the magnetic body 1 can be obtained.

FIG. 5 is a diagram comparing operation waveforms of the magnetic detection apparatuses of the first embodiment and the second embodiment. FIG. In this figure, when comparing the largest position of the shift | offset | difference of each detection position, it turns out that the magnitude | size of the shift | offset | difference of the detection position is smaller in Embodiment 2 than Embodiment 1.

Embodiment 3.

Fig. 6 (a) is a perspective view of the magnetic detection device of Embodiment 3 of the present invention, Fig. 6 (b) is a partial plan view of the magnetic detection device of Fig. 6 (a), and Fig. 6 (c) is Fig. 6 (a). Is a pattern diagram of a magnetoresistive segment.

In this embodiment, the opposing distance of the distal end surface of the toothed portion 1a with respect to the second magnetoresistive segment 2b and the third magnetoresistive segment 2c, the first magnetoresistive segment 2a, and The opposing distances of the distal end surface of the toothed portion 1a with respect to the fourth magnetoresistive segment 2d are different.

The other configuration is the same as that of the second embodiment.

FIG. 7 is an operation waveform diagram showing the difference between the opposing distances as M and dividing the time between the large and the small GAP when the values of M are -0.1 mm, 0 mm, and +0.1 mm, respectively.

In this figure, it can be seen that the deviation of detection in the magnitude of the GAP is small compared to the case of 0 mm and +0.1 mm in the case where M = -0.1 mm.

In this way, the decrease in detection performance caused by increasing the GAP by adjusting the value of M can be suppressed.

Embodiment 4.

In this embodiment, the second magnetoresistive segment 2b and the third magnetoresistive segment 2c and the salient pole portions 5a and 5b on the center line between the pair of salient pole portions 5a and 5b. The detection accuracy of the rotational position of the magnetic body 1 is adjusted by adjusting the distance N (see FIG. 6 (c)) between the first magnetoresistive segment 2a and the fourth magnetoresistive segment 2d in the vicinity of. Is an example of raising

8 shows the relationship between this segment pitch N and the differential amplified output MIN amplitude. Here, the differential amplification output MIN amplitude refers to the width when the difference between the differential amplification output voltage and the comparison voltage is minimum. The smaller the value of the MIN amplitude, the lower the position detection accuracy. In the example of FIG. Can be obtained, and high detection performance is secured.

Embodiment 5.

In this embodiment, it is an example which raises the detection precision of the rotation position of the magnetic body 1 by adjusting the opposing distance between the opposing pole parts 5a and 5b in relationship with the segment pitch N. In FIG.

9 shows, as one example, the distance between the salient pole portion 5a and the salient pole portion 5b when the segment pitch N is 2.5 mm, that is, the relationship between the salient pole pitch and the differential amplified output MIN amplitude.

In the example of Fig. 9, when the protrusion pole pitch is 5 mm or more (two times or more of the magnetoresistive segment pitch N), a differential amplification output capable of detecting the rotational position of the magnetic body 1 can be obtained.

Embodiment 6.

In this embodiment, a large magnetoresistive element (hereinafter referred to as GMR) is used as the magnetoelectric conversion element.

The GMR element is a laminate in which a magnetic layer having a thickness of several tens of angstroms and a nonmagnetic layer is alternately stacked in a so-called angstrom, a so-called artificial lattice film, (Fe / Cr) n, (firm alloy / Cu / Co / Cu) n, ( Co / Cu) n is known, which has a particularly large MR effect (MR change rate) compared to the magnetoresistive segment (hereinafter referred to as a GMR element), and exists only in the relative angle of the fragrance of magnetization of adjacent magnetic layers, thereby causing an external magnetic field. Is a device of in-plane potatoes, where n produces the same resistance change no matter what angle difference the current has (n is the number of layers). However, it is also an element that can add anisotropy by narrowing the width of the magnetoresistive pattern.

Fig. 10 is a device having hysteresis in the resistance value change due to the change in the applied magnetic field, and in that the temperature characteristic, particularly the temperature coefficient, is large (Fig. 10 shows the MR loop characteristic of the GMR element).

Thus, by using the GMR element in the magnetoelectric conversion element, the SN ratio can be improved and the noise content can be increased.

Embodiment 7.

11 is an electric circuit diagram of the magnetic detection device of the present embodiment, and FIG. 12 is an operation waveform diagram of the magnetic detection device.

In this embodiment, the processing circuit section 2 again has the midpoint output of the first magnetoresistive segment 2a and the second magnetoresistive segment 2b and the third magnetoresistive segment ( Each of the outputs obtained from the midpoint outputs of 2c) and the fourth magnetoresistive segment 2d has a differential flip-flop circuit 20 that detects the rotational direction of the magnetic body 1.

Further, the processing circuit section 2 includes a first differential amplifier circuit 13A for amplifying a signal in which resistance change at the mid-island points of the first and second magnetoresistive segments 2a and 2b is converted into voltage change. The first comparison circuit 14A and the output circuit 15 are incorporated. The processing circuit section 2 further includes a second differential amplification algorithm 13B and a second for amplifying a signal in which the resistance change at the neutral point of the magnetoresistive segments 2c and 2d of the third and fourth is changed due to the voltage change. A comparison circuit 14B and a differential flip flop circuit (D-FF circuit) 20 are incorporated.

In this embodiment, the resistance values of the first magnetoresistive segment 2a and the second magnetoresistive segment 2b change in correspondence with the shape of the magnetic movable body 1, and from the first differential amplifier circuit 13A, Also changes the output. Then, the amplification circuit output is waveform-shape and a final output signal of "1" or "0" is obtained corresponding to the groove 1b of the toothed portion 1a of the magnetic body 1.

Similarly, the resistance values of the third magnetoresistive segment 2c and the fourth magnetoresistive segment 2d change in correspondence with the shape of the magnetic body 1, and the output from the second amplifier circuit 13B is also converted. do. Then, the amplification circuit output is waveform-shaped, and the final output signal of "1" or "0" is obtained corresponding to the tooth 1a and the groove 1b of the magnetic moving body 1. These two output signals are input to the DF circuit 20, the output of the D-FF circuit 20 is low when the magnetic body 1 is blackout, and the output of the D-FF circuit 20 when the reverse is reversed. This high becomes possible and the inversion of the magnetic body 1 can be detected.

In addition, in the above embodiment, the magnetic body 1 has a disc shape in which the toothed portion 1a is formed in the periphery of the periphery, and is rotated in the circumferential direction, but is not limited thereto. It may be a magnetic body having a reciprocating linear motion.

In this case, the magnetic field is applied to the magnetic field from the magnet in a direction perpendicular to the plane formed by the linear movement of the magnetic body, and the first magnetoelectric conversion element is on the line facing the magnetic body when viewed in the vertical direction. It is located approximately on the center line of the magnet.

As described above, according to the magnetic detection device according to the present invention, the first magnetic conversion element and the second magnetic conversion element are formed apart from the magnetic moving body on the plane of the moving magnetic body with the convex portion formed at the edge. A magnet for applying a magnetic field to the processing circuit section having a bridge circuit by an element, the magnetic field applying to the first magnet-converting element and the second magnet-converting element, and at the same time perpendicular to the plane of the moving direction of the magnetic body. And the second magneto-conversion device is disposed on an approximately center line of the magnet on a line facing the magnetic body when viewed along the vertical direction, and includes the first magneto-electric conversion device and the second. The differential output is obtained from the output of the magnetoelectric conversion element of When a GAP between the magnetic moving body is large it can be obtained good detection performance.

Claims (3)

A processing circuit portion having a convex portion formed at the edge and disposed away from the magnetic moving body on a plane of the moving magnetic body, wherein the processing circuit part has a bridge circuit by a first magnetoelectric conversion element and a second magnetoelectric conversion element; A magnet for applying a magnetic field in a direction perpendicular to the plane of the moving direction of the magnetic body, the magnetoelectric element being applied to the magnetoelectric conversion element and the second magnetoelectric conversion element. When viewed along the line, the magnetic detection is arranged on a substantially centerline of the magnet on a line facing the magnetic body and obtains a differential output from the outputs of the first and second magneto-electric conversion elements. Device. 2. The magnetic detection device of claim 1, wherein the magnetic body is configured to rotate in a circumferential direction in a disk shape having a toothed portion formed in a peripheral portion thereof. 3. A magnetic body guide according to claim 2, wherein a magnetic guide having a pair of protrusions opposed to each other in the circumferential direction is provided between the processing circuit portion and the magnet, and the second magneto-electric conversion element includes a pair of the protrusions. A magnetic detection device arranged on an approximately center line of the liver and at the same time the first magnetic conversion element is arranged on one side of the salient pole portion.