JPH07294540A - Magnetism detection device - Google Patents

Abstract

PURPOSE:To provide a magnetism detection device capable of being reduced in size and of preventing a crack of a waveform of varied magnetism. CONSTITUTION:A support plate 1 is provided with a bias magnet 2. The bias magnet 2 generates a magnetic field toward a gear 7. A basic board 3 is stuck to the support plate 1 and is coated with a magnetoresistance element by vaporization. The magnetoresistance element is disposed in parallel to a magnetized face of the bias magnet 2. The magnetoresistance element is disposed in parallel to the N pole magnetized face of the bias magnet 2 and inclined at about 45 degrees with respect to a vector toward a circumferential side thereof. The variation of the vector along the rotation of the gear 7 that is in parallel to the N pole magnetized face of the bias magnet 2 toward the circumferential side in the bias magnetic field causes the variation of the resistance value of the magnetoresistance element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic detector for detecting movement such as movement of an object to be detected by utilizing a resistance change of a magnetoresistive element.

[0002]

2. Description of the Related Art Conventionally, a gear proximity type rotation sensor utilizing a magnetoresistive element has been disclosed in Japanese Patent Laid-Open No. 3-195970. This sensor is provided with measures against waveform breakage of the resistance change waveform. This technique will be described with reference to FIG. A magnetoresistive element 21 is vapor-deposited on the substrate 20. The bias magnet 23 is attached to one surface of the support plate 22, and the substrate 20 is attached to the other surface of the support plate 22 perpendicularly to the magnetized surface 23 a of the bias magnet 23. Further, on the substrate 20, the magnetic vector generated by the magnetic resistance element 21 from the bias magnet 23 (magnetization surface 2
The component B _{Y in the} direction perpendicular to 3a) is rotated by a predetermined angle (see FIG. 21).
It is arranged at an angle of 45 degrees. And the gear 24
The change in the direction of the magnetic vector B _Y due to the rotation of is detected as the resistance change by the magnetoresistive element 21.

[0003]

However, the substrate 20
The (magnetoresistive element 21) is attached to the magnetized surface 23 of the bias magnet 23.
Since the sensor is arranged perpendicular to a, the sensor becomes large in the direction perpendicular to the magnetized surface 23a of the bias magnet 23.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic detection device which can be miniaturized and can prevent the waveform crack of the resistance change waveform.

[0005]

According to a first aspect of the present invention, there is provided a bias magnet, which has a magnetized surface facing a detection target having a magnetic material, and which generates a bias magnetic field toward the detection target. A magnetoresistive element arranged in a bias magnetic field, wherein the magnetoresistive element causes a resistance change due to a change in the bias magnetic field from the bias magnet to the detected object accompanying the movement of the detected object. In the magnetic detection device described above, the magnetoresistive element is arranged parallel to the magnetized surface of the bias magnet, and a magnetic vector parallel to the magnetized surface of the bias magnet in the bias magnetic field and directed toward the outer peripheral side. Alternatively, the magnetic detection device is arranged so as to be inclined at a predetermined angle with respect to the magnetic vector going from the outer circumference side to the inner side so as to detect the change of the magnetic vector. To.

A second aspect of the present invention has as its gist a magnetic detection device in which the magnetoresistive element according to the first aspect of the invention is arranged at an angle of approximately 45 degrees with respect to the magnetic vector.

According to a third aspect of the present invention, the magnetoresistive element is 30 to 150 degrees or 210 to the moving direction of the object to be detected in the first or second aspect of the invention.
The gist is a magnetic detection device arranged at a position rotated by 330 degrees.

According to a fourth aspect of the present invention, the magnetoresistive element is set to 90 degrees or 270 with respect to the movement direction of the object to be detected in the invention according to any one of the first to third aspects.
The gist is a magnetic detection device arranged at a position rotated by a degree.

A fifth aspect of the present invention has as its gist a magnetic detection device in which the magnetoresistive element according to any one of the first to fourth aspects is arranged near an outer peripheral surface of a bias magnet.

[0010]

According to the first aspect of the present invention, when the object to be detected moves, a magnetic vector parallel to the magnetized surface of the bias magnet in the bias magnetic field and directed toward the outer peripheral side or from the outer peripheral side toward the inner side. The direction of the magnetic vector going toward changes. The change in the direction of this vector is detected as a resistance change by the magnetoresistive element arranged in parallel with the magnetized surface of the bias magnet. At this time, since the magnetoresistive element is arranged parallel to the magnetized surface of the bias magnet, compared to the case where the magnetoresistive element is arranged perpendicularly to the magnetized surface of the bias magnet,
It becomes smaller in the direction perpendicular to the magnetized surface of the bias magnet. or,
A magnetic resistance element is arranged at a predetermined angle with respect to a magnetic vector that is parallel to the magnetized surface of the bias magnet in the bias magnetic field and that is directed toward the outer circumference side or inward from the outer circumference side. Since the change is detected, the resistance change waveform is prevented from being broken.

According to the invention of claim 2, claim 1
In addition to the effect of the invention described in (1),
Since the magnetoresistive element is arranged at an angle of about 45 degrees, the resistance change rate has the maximum value with respect to the vector fluctuation.

According to the invention of claim 3, claim 1
Alternatively, in addition to the function of the invention described in 2, the magnetoresistive element is 30 to 150 degrees or
It is arranged at a position rotated by 0 to 330 degrees, and the resistance change rate of the magnetoresistive element increases.

According to the invention of claim 4, claim 1
In addition to the operation of the invention described in any one of 1 to 3, the magnetoresistive element is 90 degrees or 2 with respect to the movement direction of the detection target.
It is arranged at a position rotated by 70 degrees, and the resistance change rate of the magnetoresistive element is further increased.

According to a fifth aspect of the present invention, in addition to the operation of the first aspect of the present invention, the magnetoresistive element is arranged near the outer peripheral surface of the bias magnet, and the sufficient resistance change rate is obtained. Is obtained.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a plan view of a magnetic rotation detecting device of this embodiment. Further, FIG. 2 shows a view as seen from an arrow A in FIG.

The support plate 1 has a rectangular shape. The bias magnet 2 made of a permanent magnet has a cylindrical shape, and the outer diameter of the bias magnet 2 is 7 mm. The bias magnet 2 has one surface magnetized to the N pole and the other surface magnetized to the S pole. Then, one surface of the bias magnet 2 (N-pole magnetized surface 2a) is bonded to one surface of the support plate 1.

FIG. 3 shows the N pole magnetized surface 2 of the bias magnet 2.
The state of the magnetic force line from a to the S pole magnetized surface is shown. Further, FIG. 4 shows a view from the arrow B of FIG. As shown in FIG. 3, at a position P1 slightly apart from the N-pole magnetized surface 2a of the bias magnet 2, the magnetic vector B is parallel to the N-pole magnetized surface 2a of the bias magnet 2 and extends toward the outer peripheral side. Vector B
_X and the vector B _{Y in the} direction perpendicular to the N-pole magnetized surface 2a of the bias magnet 2 are combined. Hereinafter, the vector B _X parallel to the N-pole magnetized surface 2a of the bias magnet 2 and directed to the outer peripheral side will be referred to as "N-pole magnetized surface parallel component vector", and the direction perpendicular to the N-pole magnetized surface 2a of the bias magnet 2 will be described. The vector B _{Y of is referred} to as “N-pole magnetized surface vertical component vector”.

Further, as shown in FIG. 1, one surface of the rectangular substrate 3 is bonded to the other surface of the support plate 1.
As shown in FIG. 5, two magnetoresistive elements 4 and 5 are formed on the surface of the substrate 3 by vapor deposition. Thus, the magnetoresistive elements 4 and 5 are arranged in parallel to the N-pole magnetized surface 2 a of the bias magnet 2.

The magnetoresistive elements 4 and 5 are strip-shaped and extend linearly. The magnetoresistive elements 4 and 5 are bias magnets 2.
From the magnetic vector B generated from the magnetic field B, the pair of magnetic poles is arranged at approximately plus / minus 45 degrees with respect to the direction of the N-pole magnetized surface parallel component vector B _X (shown by W in FIG. 5). The width of the magnetoresistive elements 4 and 5 is 8 μm, and the N-pole magnetized surface parallel component vector B _X and the N-pole magnetized surface vertical component vector B _{Y at} the installation positions of the magnetoresistive elements 4 and 5 are both 100.
When it is Gauss or more, the magnetoresistive elements 4 and 5 have saturation magnetic field strength or more.

Further, as shown in FIG. 5, a waveform processing circuit 6 is formed on the surface of the substrate 3. Further, as shown in FIGS.
3 are provided, and the board 9 is connected by the output lead 9
The signal from the waveform processing circuit 6 is extracted.

On the other hand, as shown in FIG. 1, the gear 7 is an object to be detected having a magnetic material, and a large number of teeth 8 are formed on the gear 7. The substrate 3 is arranged so as to face the teeth 8 of the gear 7. Further, as shown in FIG. 2, the center of the bias magnet 2 is located on the center line of the gear 7 in the thickness direction. The arrangement positions of the magnetoresistive elements 4 and 5 are
The direction is perpendicular to the gear rotation direction (direction rotated 90 ° counterclockwise to the gear rotation direction). further,
The arrangement position of the magnetoresistive elements 4 and 5 is 0.25 to 5.0 mm from the center of the bias magnet 2.

That is, the distance from the center of the bias magnet 2 to the magnetoresistive elements 4 and 5 is determined by the thickness t of the gear 7 and the diameter of the bias magnet 2, and a magnetic vector fluctuation described below occurs. And the saturation magnetic field strength of the magnetoresistive elements 4 and 5 or more.

As described above, in the magnetic circuit composed of the bias magnet 2 to the gear 7, the magnetoresistive element 4 is formed on the surface thereof.
A substrate 3 on which 5 is vapor-deposited is arranged, and the substrate 3 is arranged parallel to the N pole magnetized surface 2a of the bias magnet 2 facing the gear surface. Then, as shown in FIG. 5, the angles formed by the magnetoresistive elements 4 and 5 are such that the magnetoresistive elements 4 and 5 are approximately 45 ° with respect to the N-pole magnetized surface parallel component vector B _{X in the} magnetic vector B, respectively. It is arranged at about 90 °.

Here, the principle of magnetic detection will be described. The magnetism detected by the magnetoresistive elements 4 and 5 in this embodiment is the N-pole magnetized surface parallel component vector B _X in the magnetic vector B.
Is. When there is no gear 7 facing the N pole magnetized surface 2a of the bias magnet 2, the N pole magnetized surface parallel component vector B _X becomes the direction W shown in FIG. When the gear 7 is present, the direction W of the N-pole magnetized surface parallel component vector B _X , which is drawn by the teeth 8 of the gear 7 by the rotation of the gear 7, changes in the range of W1 to W2, and the center of the bias magnet 2 is used as a reference. The deflection angle of the N-pole magnetized surface parallel component vector B _X (direction change of the magnetic vector B _X at the arrangement position of the magnetoresistive elements 4 and 5) is Δθ. The deflection angle Δθ depends on the distance between the bias magnet 2 and the magnetic resistance elements 4 and 5, and the distance between the magnetic resistance elements 4 and 5 and the gear 7.

It is arranged at an angle of 90 ° (each 45 ° with respect to W).
The paired magnetoresistive elements 4 and 5 are arranged as shown in FIG.
, The vector parallel to the N-pole magnetized surface in the magnetic vector
Le B _XDetects the deflection angle Δθ of each and changes the resistance in opposite phase
do. This resistance change is caused by the waveform processing on the same substrate.
It is binarized by the logic circuit 6 and the pulse corresponding to the teeth 8 of the gear 7
Output.

At this time, it has been confirmed that no waveform crack occurs in the resistance change waveform at the distance between the gear 7 and the magnetic resistance elements 4 and 5 in the actual use range. Various experiments were conducted below, and the results will be described below.

As shown in FIG. 7, when the counterclockwise angle formed by the rotation direction of the gear 7 and the magnetic resistance elements 4 and 5 of the substrate 3 is θ, the magnetic resistance when this θ is changed. The resistance change rates of the elements 4 and 5 were measured. The measurement result
This is shown in FIGS. As for the measurement conditions, as shown in FIG. 9, a rare earth magnet was used as the bias magnet 2, the diameter was 7 mm, the thickness was 4 mm, and the bias magnet 2 was separated from the outer peripheral surface by 0.5 mm. Magnetoresistive elements 4 and 5 are arranged at the positions. Further, FIG. 10 shows the measurement results when the diameter of the gear 7 is 75 mm, the number of teeth 8 of the gear 7 is “48”, and the thickness of the gear 7 is 10 mm. Also, FIG.
The gear 7 has a diameter of 85 mm and the number of teeth 8 of the gear 7 is "4.
8 ”, the measurement result when the thickness of the gear 7 is 3 mm is shown. Further, in FIGS. 10 and 11, the distance L between the magnetoresistive elements 4 and 5 and the gear 7 is set to 0.5 as shown in FIG.
The experimental results obtained by changing the values to mm, 1.0 mm, and 1.5 mm are shown.

From these FIGS. 10 and 11, θ = 0 to 360 °
In the case of other than 0, 180 °, and 360 °, the resistance change rate is obtained. Further, assuming that the detection limit of the waveform processing circuit 6 is about 0.2% in resistance change rate, about 30 ° <θ <150
It was found that the resistance change rate required for gear detection can be obtained at 0 ° and about 210 ° <θ <330 °. Furthermore, the highest rate of resistance change is θ = 90 and 270 °.
It was confirmed that That is, as shown in FIG.
When θ = 90 °, the maximum resistance change rate can be obtained.

In this way, considering the mounting error of the air gap (distance L between the magnetoresistive elements 4 and 5 and the gear 7) at the time of packaging and assembling, about 30 ° <θ <150.
It has been found that the support plate 1 (the magnetoresistive elements 4 and 5) may be arranged with respect to the gear 7 so that the angle becomes approximately 210 ° <θ <330 °.

Therefore, in FIG. 2, the magnetic resistance elements 4 and 5 are arranged at right angles (θ = 90 °) to the gear rotation direction, but 30 ° <θ <150 ° or 210 ° <.
It may be carried out in the range of θ <330 °.

Next, as shown in FIG. 12, the N-pole magnetized surface parallel component vector B _X and the N-pole magnetized surface perpendicular component at a position P2 1.2 mm away from the N-pole magnetized surface of the bias magnet 2. The measurement result of the vector B _Y is shown in FIG. Here, FIG.
As shown in, the bias magnet 2 has an outer diameter of 7 mm,
It has a thickness of 4 mm. Then, with the center of the bias magnet 2 as the reference position and the radial distance from the center of the bias magnet 2 as the horizontal axis in FIG. 14, the magnetic force of the N-pole magnetized surface parallel component vector B _X and the N-pole magnetized surface vertical component The vertical axis is the magnetic force of the vector B _Y.

From FIG. 14, the strength of the N-pole magnetized surface parallel component vector B _X becomes “0” at the center of the bias magnet 2 and is weakest, and becomes stronger as the distance from the center increases, and becomes maximum on the outer peripheral surface of the bias magnet 2. It takes a value and becomes gradually weaker as the distance from the outer peripheral surface of the bias magnet 2 increases. The magnetic force of the N-pole magnetized surface parallel component vector B _X becomes smaller than ± 100 gauss because it is ± 0.25 m from the center of the bias magnet 2.
The range is within m. In other words, if it is out of the range of ± 0.25 mm from the center of the bias magnet 2, ± 10
The magnetic force is 0 Gauss or more.

On the other hand, the magnetic force of the N-pole magnetized surface vertical component vector B _Y has a maximum value at the center of the bias magnet 2 and becomes weaker as the distance from the center increases. When the distance from the center of the bias magnet 2 is +5.0 mm or more, it becomes smaller than +100 gauss.

Therefore, the N-pole magnetized surface parallel component vector B _X
And the N-pole magnetized surface vertical component vector B _Y both become 100 gauss or more and the magnetoresistive elements 4 and 5 have the saturation magnetic field strength or more, the magnetoresistive elements 4 and 5 are set to 0. Separated by 25 mm or more and bias magnet 2
Must be within 1.5 mm from the outer peripheral surface of.

Further, in FIG. 15, the outer peripheral surface of the bias magnet 2 is used as a reference position as shown in FIG. 13, the diameter of the gear 7 is 85 mm, the number of teeth 8 of the gear 7 is “48”, and θ = 0. In this case, when the distance (air gap) from the N pole magnetized surface of the bias magnet 2 is plotted on the horizontal axis and the resistance change rate is plotted on the vertical axis, the magnetic resistance elements 4 and 5 are varied in the radial direction from the reference position. The measurement result of is shown.

From FIG. 15, as the mounting position of the magnetoresistive elements 4 and 5, the vicinity of the outer peripheral surface of the bias magnet 2 (+0.5
(mm to -1.5 mm), it was found that a sufficient resistance change rate could be obtained, and the mounting allowable range was wide.

Therefore, in FIG. 2, the installation positions of the magnetoresistive elements 4 and 5 are set to a range of 0.25 to 5 mm from the center of the bias magnet 2 (diameter 7 mm), but 3.5 mm from the center of the bias magnet 2. The bias magnet 2 may be defined near the outer peripheral surface. In this case, the required rate of resistance change can be obtained even if the position is slightly displaced.

16 and 17, the N-pole magnetized surface parallel component vector B when various bias magnets are used.
_X (Fig. 16) and N pole magnetized surface vertical component vector B
The measurement result of the magnetic force of _Y (FIG. 17) is shown. The measurement conditions are the same as the conditions for obtaining the measurement results of FIG.
The horizontal axis in FIGS. 16 and 17 indicates the distance from the center of the bias magnet.

As described above, according to this embodiment, the magnetoresistive elements 4 and 5 are arranged in parallel with the N pole magnetized surface of the bias magnet 2 and are arranged on the N pole magnetized surface of the bias magnet 2 in the bias magnetic field. The magnets are arranged parallel to each other and inclined at a predetermined angle (approximately 90 degrees) with respect to the magnetic vector B _X toward the outer peripheral side, and changes in the magnetic vector B _X are detected. Therefore, when the substrate 3 is arranged perpendicular to the magnetized surface of the N pole of the bias magnet 2, the sensor is structurally large in the direction perpendicular to the magnetized surface, but the magnetoresistive elements 4 and 5 are biased. Since the magnet 2 is arranged parallel to the magnetized surface of the N pole, the size can be reduced. That is, by arranging the substrate 3 in parallel with the N-polarized surface, the substrate 3 can be structurally made smaller in the direction perpendicular to the N-polarized surface than in the case where the substrate 3 is arranged perpendicularly with the N-polarized surface. . Further, in the conventional apparatus shown in FIG. 21, the substrate 20 is attached to the magnetized surface 23a of the bias magnet 23.
However, in the present embodiment, since the bias magnet 2, the support plate 1 and the substrate 3 are arranged in parallel to each other, they can be easily held with an adhesive or the like, and the assembling can be easily performed with high accuracy. Can also be good.

Further, the magnetoresistive elements 4 and 5 are parallel to the magnetized surface of the N pole of the bias magnet 2 in the bias magnetic field and are at a predetermined angle (approximately 90) with respect to the magnetic vector B _X directed toward the outer peripheral side.
Since it is arranged so as to be inclined, the resistance change waveform is prevented from being broken. In particular, the magnetic resistance elements 4 and 5 are connected to the magnetic vector B.
_Since they are arranged at an angle of approximately 45 degrees with respect to _X , the resistance change rate has the maximum value with respect to the vector fluctuation, and the resistance change rate can be increased.

Further, since the magnetoresistive elements 4 and 5 are arranged at the positions rotated by 30 to 150 degrees or 210 to 330 degrees with respect to the rotation direction of the gear 7, the rate of resistance change becomes large and the rate of resistance change is surely secured. can do.

Further, since the magnetoresistive elements 4 and 5 are arranged at positions rotated by 90 degrees or 270 degrees with respect to the rotation direction of the gear 7, the rate of resistance change is further increased. Further, the magnetoresistive elements 4 and 5 are arranged so that the necessary vector B _X is obtained from the center of the bias magnet 2 and the required vector B _Y is obtained from the outer circumference of the bias magnet 2 too far. The range was set to be 0.25 mm or more from the center of the bias magnet 2 and not more than 1.5 mm from the outer peripheral surface. Accordingly, the magnetic field strength is equal to or higher than the saturation magnetic field strength of the magnetoresistive elements 4 and 5 (both B _X and _BY are 100 Gauss or more), and the magnetic vector B _X due to the rotation of the gear 7 is increased.
Can be obtained.

In particular, by disposing the magnetoresistive elements 4 and 5 near the outer peripheral surface of the bias magnet 2, a sufficient resistance change rate can be obtained even if there is some positional deviation during mounting.
Further, as shown in FIG. 5, the two magnetoresistive elements 4 and 5 are arranged close to a predetermined magnetic vector to detect a change in the predetermined magnetic vector, so that the change in the magnetic vector is stabilized. In addition to the above, the substrate area can be reduced when the magnetoresistive element is formed on one substrate.

Another aspect of the present invention will be described below. In the above embodiment, the magnetoresistive elements 4 and 5 are arranged so as to extend in the direction of approximately plus / minus 45 ° with respect to the direction (W) of the magnetic vector B _X as shown in FIG. 5, but not 45 °. Alternatively, for example, as shown in FIG. 18, the magnetoresistive elements 4 and 5 may be arranged so as to extend in the plus / minus 60 ° direction with respect to the direction (W) of the magnetic vector B _X , or as shown in FIG. in, or arranged to extend the magneto-resistance elements 4 and 5 in the direction of plus or minus 135 ° to the direction of the magnetic vector B _X (W), further, as shown in FIG. 20, the magnetic vector B _X The magnetoresistive elements 4 and 5 may be arranged at different angles with respect to the direction (W) (see FIG. 2).
At 0, the magnetoresistive element 4 is at 45 ° and the magnetoresistive element 5 is at 6 °.
It is placed at 0 °). As shown in FIG. 19, that is disposed so as to extend the magneto-resistance elements 4 and 5 in the direction of plus or minus 135 ° to the direction of the magnetic vector B _X (W), the magnetic vector B _X and the magnetic Resistance element 4,
This means that the angle formed by 5 and 45 is 45 °, and the magnetoresistive elements 4 and 5 are arranged at an angle of 45 ° with respect to the magnetic vector B _X.

That is, the present invention is disclosed in JP-A-3-195970.
The idea equivalent to the magnetic detection device shown in the publication is applied, and the resistance change is detected by detecting the magnetic vector changing in the plane parallel to the formation surface of the magnetoresistive element. When the detection signal obtained by the above is binarized by the waveform processing circuit 6, the waveform breaking phenomenon in which the output pulse is doubled when the air gap between the object to be detected and the magnetic detection element is narrowed is prevented. It was made possible. Therefore, in the above embodiment, the angle between the magnetoresistive elements 4 and 5 and the direction of the magnetic vector B _X (the same radial direction) does not have to be 45 °, and the magnetic vector that changes according to the movement of the detected object The magnetoresistive elements 4 and 5 may be arranged so that the formed angles are different. However, as described in the above publication, when the magnetic vector B _X swings in the range of W1 to W2 around the direction W as shown in FIG. 5, when the angle is 45 ° (or 135 °),
Since the magnetoresistive element has the highest rate of resistance change, it is best to arrange it at 45 °. Further, the magnetoresistive elements 4 and 5
Since the angle formed by and is 90 °, the directions of resistance changes of the two magnetoresistive elements are in opposite phases, and the output voltage can be maximized.

In the above embodiment, the N pole magnetized surface of the bias magnet 2 is opposed to the gear 1 and the magnetic vector B _X toward the outer circumference of the bias magnet 2 is used for magnetic detection.
The S pole magnetized surface of the bias magnet 2 may be opposed to the object to be detected (gear 1) and magnetic detection may be performed using a magnetic vector from the outer peripheral side of the bias magnet 2 toward the center of the magnetized surface.
That is, the magnetoresistive elements 4 and 5 are arranged parallel to the magnetized surface of the bias magnet 2, and the magnetic vector parallel to the magnetized surface of the bias magnet facing the object to be detected and directed inward from the outer peripheral side is provided. Alternatively, they may be arranged at a predetermined angle to detect a change in the magnetic vector.

Further, in the above embodiment, as the bias magnet,
Although the cylindrical shape is used, the bias magnet may have another shape as long as a magnetic vector is generated from the magnet center to the outer peripheral side.

[0048]

As described in detail above, according to the invention described in claim 1, it is possible to reduce the size and prevent the waveform breakage of the resistance change waveform.

According to the invention of claim 2, claim 1
In addition to the effect of the invention described in (1), the rate of resistance change can be increased. According to the invention of claim 3, claim 1
In addition to the effect of the invention described in (1), the rate of resistance change can be increased.

According to the invention of claim 4, claim 1
In addition to the effect of the invention described in any one of 1 to 3, the rate of resistance change can be further increased. According to the invention described in claim 5, in addition to the effect of the invention described in any one of claims 1 to 4, a sufficient resistance change rate can be obtained even if the installation position of the magnetoresistive element is slightly deviated.

[Brief description of drawings]

FIG. 1 is a plan view of a magnetic rotation detection device according to an embodiment.

FIG. 2 is a view on arrow A in FIG.

FIG. 3 is a side view showing magnetic lines of force of a bias magnet.

FIG. 4 is a view on arrow B of FIG.

FIG. 5 is a plan view of a substrate.

FIG. 6 is a waveform chart for explaining the operation.

FIG. 7 is an explanatory diagram for explaining a positional relationship between a gear and a magnetoresistive element.

FIG. 8 is an explanatory diagram for explaining a positional relationship between a gear and a magnetoresistive element.

FIG. 9 is an arrangement diagram showing an arrangement of a bias magnet and a magnetoresistive element.

FIG. 10 is a graph showing the measurement results of the resistance change rate with respect to the element arrangement angle θ.

FIG. 11 is a graph showing the measurement results of the resistance change rate with respect to the element arrangement angle θ.

FIG. 12 is a side view of a bias magnet.

FIG. 13 is a side view of a bias magnet.

FIG. 14 is a graph showing the measurement results of the magnetic force with respect to the distance from the center of the magnet.

FIG. 15 is a graph showing the measurement results of the resistance change rate with respect to the air gap.

FIG. 16 is a graph showing the measurement results of B _X magnetic force with respect to the distance from the magnet center.

FIG. 17 is a graph showing the measurement results of the B _Y magnetic force with respect to the distance from the magnet center.

FIG. 18 is a plan view of another example of the substrate.

FIG. 19 is a plan view of another example of the substrate.

FIG. 20 is a plan view of another example of the substrate.

FIG. 21 is a plan view of a conventional rotation sensor.

[Explanation of symbols]

2 ... Bias magnet, 3 ... Substrate, 4, 5 ... Magnetoresistive element,
7 ... Gear to be detected

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

Claims (5)

[Claims] 1. A bias magnet, which has a magnetized surface facing a detection target having a magnetic material, generates a bias magnetic field toward the detection target, and a magnetoresistive element arranged in the bias magnetic field. A magnetic detection device configured to generate a resistance change by a change of a bias magnetic field from the bias magnet to the detection target with the movement of the detection target in the magnetic resistance element, For the magnetic vector that is arranged parallel to the magnetized surface of the bias magnet and that is parallel to the magnetized surface of the bias magnet in the bias magnetic field and that is directed toward the outer circumference side or toward the inner side from the outer circumference side. A magnetic detection device, wherein the magnetic detection device is arranged at a predetermined angle so as to detect a change in the magnetic vector. 2. The magnetic detection device according to claim 1, wherein the magnetoresistive element is arranged so as to be inclined by about 45 degrees with respect to the magnetic vector. 3. The magnetic detection device according to claim 1, wherein the magnetoresistive element is arranged at a position rotated by 30 to 150 degrees or 210 to 330 degrees with respect to the movement direction of the object to be detected. . 4. The magnetic detection according to claim 1, wherein the magnetoresistive element is arranged at a position rotated by 90 degrees or 270 degrees with respect to the movement direction of the object to be detected. apparatus. 5. The magnetic detection device according to claim 1, wherein the magnetoresistive element is arranged near an outer peripheral surface of a bias magnet.