JPH09318386A - Detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the movement of a magnetic substance stably by using a magnetic field generating means having a plurality of magnetic poles, in an apparatus for detecting the movement of the magnetic substance by measuring the change of a magnetic field with a magnetic detecting element, and making the quantity of the change of a magnetic field to be applied to the magnetic field. SOLUTION: A giant magnetoresistance element 10 for example is arranged as a magnetic detecting element at a specified interval with a magnetic rotor having at least a recession and a protrusion. Magnets 5 give a magnetic field to the element 10. If the rotor 2 rotates, the magnetic field on the magnetically sensitive surface 10b of the element to changes, and the resistance value of a magnetic resistance pattern which the element 10 has changes. This resistance value change is processed by a processing means composed of a bridge circuit, etc., and an output which corresponds to the protrusion and recession of the rotor is obtained. Since magnets 5 are arranged for the element 10 so as to form a plurality of poles, the quantity of the change of the magnetic field corresponding to the protrusion and recession is large, and high precision detection is feasible. It is possible to replace a part of the magnets with a magnetic flux guide of a magnetic substance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detecting device for detecting a change in a magnetic field due to movement of a magnetic body moving body, and more particularly to a detecting device suitable for use in detecting rotation information of an internal combustion engine. is there.

[0002]

2. Description of the Related Art Generally, a magnetoresistive element (hereinafter referred to as an MR element) is a ferromagnetic material (for example, Ni-Fe, Ni-Co).
Etc.) An element whose resistance value changes depending on the angle formed by the magnetization direction of the thin film and the current direction. This MR element has a minimum resistance value when the current direction and the magnetization direction intersect at right angles,
The resistance value becomes maximum when the current direction and the magnetization direction are the same or completely opposite to each other at 0 degree. This change in resistance value is called the MR effect or MR change rate, and is generally Ni-F.
e is 2 to 3%, and Ni-Co is 5 to 6%.

FIG. 24 is a block diagram showing a conventional detection device. FIG. 24 (a) is a side view thereof, and FIG. 24 (b) is a perspective view thereof. This detection device includes a rotating shaft 1, a magnetic rotating body 2 having at least one unevenness and rotating in synchronization with the rotating shaft 1, and a magnetic body rotating body 2 arranged with a predetermined gap. The MR element 3 has a magnetoresistive pattern 3a and a thin film surface (magnetically sensitive surface) 3b. Therefore, the magnetic field of the magnetic sensitive surface 3b of the MR element 3 changes as the magnetic body rotating body 2 rotates, and the resistance value of the magnetoresistive pattern 3a changes.

FIG. 25 shows the MR element 3 and the magnet 4 of FIG.
FIG. 4 is an enlarged perspective view showing a magnet 4 having one magnetic pole having polarities N and S. FIG. FIG. 26 shows the unevenness of the magnetic rotating body and M.
It is a figure which shows the distribution of the magnetic field between R elements. In the figure, as shown in FIG. 26A, when the MR element 3 faces the convex portion of the magnetic rotating body 2, the magnetic field generated from the N pole of the magnet 4 is applied to the magnetic sensitive surface 3 b of the MR element 3. Through the magnetic body rotating body 2
Of the magnet 4 and the south pole of the magnet 4 through the surrounding air. On the other hand, as shown in FIG.
When the MR element 3 faces the concave portion of the magnetic body rotating body 2, the magnetic field generated by the N pole of the magnet 4 is applied to the magnetic sensitive surface 3 of the MR element 3.
through b through the side end of the concave portion of the magnetic body rotating body 2,
Further, the distribution reaches the south pole of the magnet 4 through the surrounding air.

FIG. 27 schematically shows a circuit configuration of a conventional detection device, in which the MR element 3 connected to a constant current source is
The voltage change signal S _VV corresponding to the unevenness of the magnetic body rotating body 2 is output. Now, when the magnetic body rotating body 2 rotates in synchronization with the rotating shaft 1, as shown in FIG.
A magnetic field is generated between the element 3 and the magnetic body rotating body 2 to change the magnetic field of the magnetic sensitive surface 3b of the MR element 3, and the output of the MR element 3 (voltage change signal S _VV ) is obtained. A waveform obtained by amplifying this output by a differential amplifier circuit (not shown) or the like is shown by a broken line a in FIG. 6D corresponding to the unevenness of the magnetic body rotating body 2 shown in FIG. ing.

[0006]

However, since the conventional detecting device is constructed as described above, it has the following problems. That is, when the magnet 4 that gives a magnetic field to the MR element 3 has one magnetic pole, and the MR element 3 faces the convex portion of the magnetic body rotating body 2 ((a) of FIG. 26), the MR element 3 Since the magnetic field applied perpendicularly to the magnetic sensitive surface 3b is substantially limited to a part of the magnetic sensitive surface 3b at the central portion of the magnetic sensitive surface 3b of the MR element 3, the magnetic field strength is weak,
Further, when the MR element 3 faces the concave portion of the magnetic body rotating body 2 ((b) of FIG. 26), a line and a magnetic field drawn perpendicularly to the magnetic body rotating body 2 from the center of the magnet 4 shown by the alternate long and short dash line. The angle θ ₁ formed by and is small because the magnetic field spreads toward the side end of the concave portion of the magnetic body rotating body 2, and as a result, the magnetic field strength is also small.

Therefore, the amount of change in the magnetic field applied to the MR element 3 by the magnet 4 due to the uneven portion of the magnetic rotor 2 is small, and therefore the amount of change in the magnetic field on the magnetic sensitive surface of the MR element is small, that is, However, since the change in the resistance value of the magnetoresistive pattern is small and the detection output is small as a result, there is a problem that the detection cannot be performed efficiently and the detection accuracy is poor.

The present invention has been made in order to solve such a problem, and makes it possible to increase the amount of change in the magnetic field applied to the magnetic detecting element at the uneven portion of the magnetic body moving body such as the magnetic body rotating body. Then, it is an object of the present invention to obtain a detection device having excellent detection accuracy, which can obtain a signal corresponding to the uneven portion of the magnetic body moving body with high accuracy and stability.

[0009]

According to a first aspect of the present invention, there is provided a detecting device having a plurality of magnetic poles, a magnetic field generating means for generating a magnetic field, and a magnetic field generating means arranged with a predetermined gap. It is provided with a magnetic field change applying means for changing the magnetic field generated by the magnetic field generating means, and a magnetic detection element whose resistance value changes according to the magnetic field changed by the magnetic field change applying means.

According to a second aspect of the present invention, there is provided the detection device according to the first aspect, wherein the magnetic field generating means is composed of a magnet and a magnetic flux guide having a polarity opposite to that of the magnet.

According to a third aspect of the present invention, there is provided the detection device according to the second aspect, wherein a part of the magnet is used as the magnetic flux guide.

According to a fourth aspect of the present invention, there is provided the detection device according to the second aspect, wherein a magnetic body is used as the magnetic flux guide.

According to a fifth aspect of the present invention, there is provided the detection device according to the first aspect, wherein the magnetic field change imparting means is constituted by a magnetic body moving body having at least one concavity and convexity.

According to a sixth aspect of the present invention, there is provided a detection device according to any one of the first to fifth aspects, in which a bridge circuit using a magnetic detection element on at least one side and signal processing of an output of the bridge circuit. And signal processing means.

According to a seventh aspect of the present invention, in the detecting device according to any one of the first to sixth aspects, the magnetic body moving body is a magnetic body rotating body that rotates in synchronization with a rotation axis. .

According to an eighth aspect of the present invention, there is provided the detection device according to the seventh aspect, further comprising a detection device main body including at least a magnetic detection element, wherein the magnetic body rotating body is mounted on a crankshaft or a camshaft of an internal combustion engine. The detection device main body is arranged in the vicinity of the internal combustion engine so that the magnetic rotating body faces the magnetic detection element.

According to a ninth aspect of the present invention, there is provided the detection device according to the eighth aspect, wherein the detection device main body is arranged in the rotation axis direction with respect to the magnetic body rotating body.

According to a tenth aspect of the present invention, there is provided a detection device,
In the invention of claim 9, the main body of the detection device is provided with a housing containing at least a magnetic detection element, and the magnetic body rotating body is provided in a space formed on a side surface of the housing so that at least a peripheral portion of the magnetic body rotating body is magnetic. It is arranged so as to face the detection element.

[0019]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a detection apparatus according to the present invention. Embodiment 1. FIG. 1 is a block diagram showing a first embodiment of the present invention. FIG. 1 (a) is a side view thereof, and FIG. 1 (b).
Is a perspective view thereof. This detection device includes a rotating shaft 1 and a magnetic rotating body 2 as a magnetic field change imparting means that has at least one unevenness and rotates in synchronization with the rotating shaft 1.
A giant magnetoresistive element (hereinafter referred to as a GMR element) 10 as a magnetic detection element, which is arranged with a predetermined gap with the magnetic body rotating body 2, and a magnet 5 as a magnetic field generating means for applying a magnetic field to the GMR element 10. And GMR element 10
Is a magnetoresistive pattern 10a as a magnetically sensitive pattern,
And a thin film surface (magnetic surface) 10b. Therefore, when the magnetic body rotating body 2 rotates, the magnetic sensitive surface 10b of the GMR element 10 is
Changes the magnetic field and changes the resistance value of the magnetoresistive pattern 10a.

Here, the GMR element 10 is, for example, several angstroms to several tens of angstroms described in a paper entitled "Magnetoresistance Effect of Artificial Lattice" in Japanese Society of Applied Magnetics Vol.15, No.51991, p813-821. A laminated body in which magnetic layers and nonmagnetic layers having an angstrom thickness are alternately laminated, that is, a so-called artificial lattice film, (Fe / Cr) n, (Permalloy / Cu
/ Co / Cu) n and (Co / Cu) n are known,
This has a remarkably large MR effect (MR change rate) as compared with the above-mentioned MR element, and depends only on the relative angle of the magnetization directions of the adjacent magnetic layers, so that the direction of the external magnetic field depends on the current. On the other hand, it is a so-called in-plane magnetic sensitive element that can obtain the same change in resistance value regardless of any angle difference.

Therefore, in order to detect the change in the magnetic field, the GM
The R element 10 substantially forms a magnetically sensitive surface, and an electrode is formed at each end of the magnetically sensitive surface to form a bridge circuit. A constant voltage and a constant current are applied between two opposing electrodes of the bridge circuit. It is conceivable to connect a power source, convert the resistance value change of the GMR element 10 into a voltage change, and detect the magnetic field change acting on the GMR element 10.

FIG. 2 is a block diagram showing a detecting device using the above-mentioned GMR element. This detection device is arranged with a predetermined gap from the magnetic body rotating body 2 and uses a Wheatstone bridge circuit 11 using a GMR element to which a magnetic field is given by a magnet 5 and a differential amplifier for amplifying the output of the Wheatstone bridge circuit 11. Amplifier circuit 12 and this differential amplifier circuit 1
A comparison circuit 13 that compares the output of 2 with a reference value and outputs a signal of "O" or "1", and the output of the comparison circuit 13 is further waveform-shaped and rises and falls "O" or The waveform shaping circuit 14 that outputs the signal of “1” to the output terminal 15 is provided. The differential amplifier circuit 12, the comparison circuit 13, and the waveform shaping circuit 14 constitute signal processing means.

FIG. 3 is a diagram showing an example of a specific circuit configuration of the block diagram of FIG. Wheatstone bridge circuit 1
1 is, for example, GMR elements 10A, 10 on each side.
B, 10C and 10D, and GMR elements 10A and 1
Each one end of 0C is commonly connected, is connected to the power supply terminal Vcc through the connection point 16, each one end of GMR elements 10B and 10D is commonly connected, is grounded through the connection point 17, and GM.
The other ends of the R elements 10A and 10B are connected to the connection point 18, and the other ends of the GMR elements 10C and 10D are connected to the connection point 19.

The Wheatstone bridge circuit 11
18 is connected to the inverting input terminal of the amplifier 12a of the differential amplifier circuit 12 via a resistor, and the connection point 19 is connected to the non-inverting input terminal of the amplifier 12a via a resistor and further to the resistor. Is connected to the voltage dividing circuit that constitutes the reference power source. Further, the output terminal of the amplifier 12a is connected to the inverting input terminal of the comparison circuit 13, and the non-inverting input terminal of the comparison circuit 13 is connected to the voltage dividing circuit which constitutes the reference power source and outputs its own output through the resistor. Connected to the terminal.
The output side of the comparison circuit 13 is connected to the base of the transistor 14a of the waveform shaping circuit 14, its collector is connected to the output terminal 15 and also connected to the power supply terminal Vcc via a resistor, and its emitter is grounded. .

FIG. 4 shows the GMR element 10 and the magnet 5 of FIG.
FIG. 3 is an enlarged perspective view showing a magnet 5 here,
It has two magnetic poles 5a to 5c. Then, the GMR element 10
The magnetic poles 5a to 5c of the magnet 5 are arranged so as to have three polarities S, N, and S, respectively, facing the magnetic sensitive surface 10b.
With this configuration, the magnetic field at the uneven portion when the magnetic body rotating body 2 rotates is as shown in FIG. In the figure, as shown in FIG. 5A, the GMR element 10 is a magnetic body rotating body 2.
, The magnetic field generated from the N pole of the magnetic pole 5a of the magnet 5 reaches the convex portion of the magnetic body rotating body 2 via the magnetically sensitive surface 10b of the GMR element 10, and is again perpendicular to the convex portion. G
The distribution reaches the S pole of the adjacent magnetic poles 5b and 5c through the magnetically sensitive surface 10b of the MR element 10. On the other hand, as shown in FIG. 5B, the GMR element 10 is formed in the concave portion of the magnetic rotating body 2. When facing each other, most of the magnetic field generated from the N pole of the magnetic pole 5a of the magnet 5 reaches the S pole of the immediately adjacent magnetic poles 5b and 5c via the magnetically sensitive surface 10b of the GMR element 10. Therefore, in this case, the magnetic poles 5b and 5c substantially act as a kind of magnetic flux guide.

Here, the GMR element 10 is the magnetic body rotating body 2.
When facing the convex portion of the GMR element 1 (FIG. 5A).
Since a substantially perpendicular magnetic field is applied over the entire magnetic sensitive surface 10b of 0, the magnetic field strength is large, and the GMR element 10
Is opposed to the concave portion of the magnetic body rotating body 2 ((b) of FIG. 5), the line and the magnetic field drawn perpendicularly to the magnetic body rotating body 2 from the center of the magnet 5 (of the magnetic pole 5a) shown by the alternate long and short dash line. The angle θ ₂ formed by is large because the magnetic field from the N pole of the magnetic pole 5a reaches the S pole of the immediately adjacent magnetic poles 5a and 5c, and as a result, the magnetic field strength is also large. Therefore, by the magnet 5, G
The amount of change in the magnetic field applied to the MR element 10 due to the irregularities of the magnetic rotating body 2 is large, and therefore the GMR element 1
The amount of change in the magnetic field of the magnetic sensitive surface 10b of 0 is also large, that is, the change in the resistance value of the magnetoresistive pattern is large.

Next, the operation will be described with reference to FIG. By rotating the magnetic body rotating body 2, (a) of FIG.
Corresponding to the unevenness shown in FIG. 1, the same magnetic field change is applied to the GMR elements 10A and 10D that form the Wheatstone bridge circuit 11, and the GM is applied to the GMR elements 10B and 10C.
A magnetic field change different from that of the R elements 10A and 10D is given. As a result, a magnetic field change occurs on the magnetic sensitive surfaces of the GMR elements 10A, 10D and 10B, 10C corresponding to the irregularities of the magnetic body rotating body 2, that is, substantially one GMR element.
A magnetic field change that is four times the magnetic field change of the element can be obtained, and the resistance value of the element changes in the same manner.
The maximum and minimum positions of the resistance values of B and 10C are reversed, and the midpoint voltage of the connection points 18 and 19 of the Wheatstone bridge circuit also changes as shown in (c) of FIG.

The difference in the midpoint voltage is amplified by the differential amplifier circuit 12, and the output side thereof has the magnetic property shown in FIG. 6A as shown by the solid line b in FIG. 6D. Output corresponding to the unevenness of the rotating body 2, that is, substantially one GM
An output four times that of the R element can be obtained. This differential amplifier circuit 12
The output of is compared with the reference value by the comparison circuit 13 and converted into a signal of "O" or "1", and this signal is further waveform-shaped by the waveform shaping circuit 14 and, as a result, is output to its output side, that is, the output terminal 15. As shown in (e) of FIG. 6, an output of "O" or "1" having a sharp rise and fall is obtained.

Thus, by amplifying the differential of the voltage change of the midpoint voltage, the magnetic field change of each GMR element can be effectively utilized, and the magnetic field change four times that of one GMR element can be obtained. That is, the bridge circuit configuration makes it possible to stably convert a magnetic field change due to the rotation of the magnetic body rotating body 2 into a large resistance value change amount. Therefore, the output of the differential amplifier circuit 12 also becomes large, and the margin for the judgment level for waveform shaping into the signal of “0” or “1” in the comparison circuit 13 increases, and it becomes strong against external noise. A stable signal can always be obtained. It should be noted that although the GMR element is used to configure the Wheatstone bridge circuit here, the same effect can be obtained if the bridge circuit configuration is similar.

As described above, in the present embodiment, the magnet is arranged so that the polarities thereof are the three poles S, N and S with respect to the magnetic sensitive surface of the GMR element, so that the GMR element rotates the magnetic body. When facing the convex portion of the body, a substantially perpendicular magnetic field is applied to the magnetic sensitive surface of the GMR element, and when facing the concave portion of the magnetic body rotating body, a magnetic field parallel to the magnetic sensitive surface of the GMR element is applied. It is in the applied state. As a result, the amount of change in the applied magnetic field on the magnetically sensitive surface of the GMR element is larger than in the case of the conventional arrangement in which a magnet having one magnetic pole is arranged, and the change in the magnetic field corresponding to the uneven portion of the magnetic body rotating body is accurately performed. Therefore, it becomes possible to detect efficiently, and a stable and accurate signal can be obtained. In the above description, the polarities of the magnets are three poles S, N, and S, but the same effect can be obtained even when the polarities are N, S, and N.

Embodiment 2 7 is a block diagram showing a second embodiment of the present invention. In the figure, parts corresponding to those in FIGS. 1 and 4 are designated by the same reference numerals for description. In the first embodiment, the magnets are arranged so that the polarities of the magnets are S, N, S or N, S, N. However, in the present embodiment, the magnet has one pole and is located on the side of the magnetic pole. A magnetic body is arranged as a magnetic flux guide. That is, as shown in FIG. 7, a magnet 5A having one magnetic pole 5a is provided in place of the above-mentioned magnet 5, and a predetermined shape, for example, a U-shaped magnetic body 6 is provided on the side portion of the magnet 5A so as to surround it. To place. The magnetic body 6 is arranged so that its bottom portion contacts one pole of the magnetic pole 5a, for example, the S pole. Therefore, this magnetic body 6
Has a polarity of S. The magnet 5A and the magnetic body 6 constitute magnetic field generating means.

Thus, the magnetic sensitive surface 10b of the GMR element 10 is
Facing each other, there are substantially three poles of the polarity N of the magnetic pole 5a of the magnet 5A and the polarities S, S of both ends of the magnetic body 6. With this configuration, the magnetic field at the uneven portion when the magnetic body rotating body 2 rotates is as shown in FIG. In the figure, when the GMR element 10 faces the convex portion of the magnetic body rotating body 2 as shown in FIG. 8A, the magnetic field generated from the N pole of the magnetic pole 5a of the magnet 5A is generated by the GMR element 10. Sensitive surface 10b
The distribution reaches the convex portion of the magnetic body rotating body 2 through the magnetic field, and then reaches the S poles at both ends of the magnetic body 6 through the magnetically sensitive surface 10b of the GMR element 10 perpendicularly again. ), When the GMR element 10 faces the concave portion of the magnetic body rotating body 2, most of the magnetic field generated from the N pole of the magnetic pole 5a of the magnet 5A is on the magnetic sensitive surface 10b of the GMR element 10. The distribution immediately reaches the S poles at both ends of the magnetic body 6 via the magnetic field.

Here, the GMR element 10 is the magnetic body rotating body 2.
When facing the convex portion of the GMR element 1 (FIG. 8A), the GMR element 1
Since a substantially perpendicular magnetic field is applied over the entire magnetic sensitive surface 10b of 0, the magnetic field strength is large, and the GMR element 10
Is opposed to the concave portion of the magnetic body rotating body 2 ((b) of FIG. 8), the line and the magnetic field drawn perpendicularly to the magnetic body rotating body 2 from the center (of the magnetic pole 5a) of the magnet 5A shown by the alternate long and short dash line. The angle θ ₂ formed by and is large because the magnetic field from the N pole of the magnetic pole 5a immediately reaches the S poles at both ends of the magnetic body 6, resulting in a large magnetic field strength. Therefore, by the magnet 5A, the GMR
The amount of change in the magnetic field applied to the element 10 due to the uneven portion of the magnetic body rotating body 2 is large, and therefore the amount of change in the magnetic field of the magnetic sensitive surface 10b of the GMR element 10 is also large, that is, the resistance of the magnetoresistive pattern. The value changes greatly.

As described above, also in the present embodiment, by arranging the magnet and the magnetic body so that the polarity of the magnet is N and the polarities S and S of the magnetic body are substantially three poles, the GMR element is magnetic. When facing the convex portion of the body rotating body, a substantially perpendicular magnetic field is applied to the magnetic sensitive surface of the GMR element, and when facing the concave portion of the magnetic body rotating body, the magnetic field is parallel to the magnetic sensitive surface of the GMR element. The magnetic field is applied. As a result, the amount of change in the applied magnetic field on the magnetically sensitive surface of the GMR element is larger than in the case of the conventional arrangement in which a magnet having one magnetic pole is arranged, and the change in the magnetic field corresponding to the uneven portion of the magnetic body rotating body is accurately performed. Therefore, it becomes possible to detect efficiently, and a stable and accurate signal can be obtained. Further, since the magnetic body is used as the magnetic flux guide, the cost is low. Note that, in the above description, the polarity of the magnet is the N pole, but the same effect can be obtained with the opposite S pole.

Embodiment 3 FIG. 9 is a configuration diagram showing a third embodiment of the present invention. In the figure, parts corresponding to those in FIGS. 1 and 4 are designated by the same reference numerals for description. In the first embodiment, the magnets are arranged so as to have the three poles S, N, S or N, S, N, but in the present embodiment, the magnets have the two poles N, S. Is to be arranged as follows. That is, as shown in FIG.
In place of the above, a magnet 5B as a magnetic field generating means having two magnetic poles 5a and 5b is provided, and the magnetic sensitive surface 10 of the GMR element 10 is provided.
The magnetic poles 5a and 5b of the magnet 5B are arranged so as to face b and have two polarities, N and S, respectively.

With this structure, the magnetic field at the uneven portion when the magnetic body rotating body 2 rotates is as shown in FIG. In the figure, as shown in FIG.
, The magnetic field generated by the N pole of the magnetic pole 5a of the magnet 5B reaches the convex portion of the magnetic body rotating body 2 via the magnetically sensitive surface 10b of the GMR element 10. , The distribution is perpendicular to the S pole of the adjacent magnetic pole 5b through the magnetically sensitive surface 10b of the GMR element 10 again.
(B), when the GMR element 10 faces the concave portion of the magnetic body rotating body 2, most of the magnetic field generated from the N pole of the magnetic pole 5a of the magnet 5B is magnetically sensitive to the GMR element 10. The distribution reaches the S pole of the immediately adjacent magnetic pole 5b via the surface 10b. In this case, the magnetic pole 5b substantially acts as a kind of magnetic flux guide.

Here, the GMR element 10 is the magnetic body rotating body 2.
10 (a) in FIG. 10, the magnetic field strength is large because a substantially perpendicular magnetic field is applied to the magnetic sensitive surface 10b of the GMR element 10 over almost the entire surface. 10 is opposed to the concave portion of the magnetic body rotating body 2 (see FIG. 10).
(B)) of the magnet 5B (of the magnetic pole 5a) shown by the alternate long and short dash line
The angle θ ₂ formed by the magnetic field from a line drawn from the center perpendicularly to the magnetic body rotating body 2 is large because the magnetic field from the N pole of the magnetic pole 5a reaches the S pole of the immediately adjacent magnetic pole 5a, resulting in a magnetic field. The strength also increases. Therefore, the GMR is changed by the magnet 5B.
The amount of change in the magnetic field applied to the element 10 due to the uneven portion of the magnetic body rotating body 2 is large, and therefore the amount of change in the magnetic field of the magnetic sensitive surface 10b of the GMR element 10 is also large, that is, the resistance of the magnetoresistive pattern. The value changes greatly.

As described above, also in the present embodiment, the GMR element is arranged so that the polarities thereof are the two poles of N and S with respect to the magnetic sensitive surface of the GMR element, so that the GMR element serves as a magnetic rotating body. When facing the convex portion, a magnetic field almost perpendicular to the magnetic sensitive surface of the GMR element is applied, and when facing the concave portion of the magnetic rotating body, a parallel magnetic field is applied to the magnetic sensitive surface of the GMR element. It will be in a state of being. As a result, the amount of change in the applied magnetic field on the magnetically sensitive surface of the GMR element is larger than in the case of the conventional arrangement in which a magnet having one magnetic pole is arranged, and the change in the magnetic field corresponding to the uneven portion of the magnetic body rotating body is accurately performed. Therefore, it becomes possible to detect efficiently, and a stable and accurate signal can be obtained. In the above description, the polarity of the magnet is N and S, but the same effect can be obtained with S and N having opposite polarities.

Fourth Embodiment FIG. 11 is a configuration diagram showing a fourth embodiment of the present invention. In FIG. 1, FIG.
The same reference numerals are given to the portions corresponding to those in FIG. 4 for description. In the first embodiment, the magnets are arranged so that the polarities of the magnets are S, N, S or N, S, N. However, in the present embodiment, the magnet has one pole and is located on the side of the magnetic pole. A magnetic body is arranged as a magnetic flux guide. That is, as shown in FIG. 11, a magnet 5A having one magnetic pole 5a is provided in place of the magnet 5 described above, and a magnetic body 6A having a predetermined shape, for example, an L-shape, is arranged on a side portion of the magnet 5A. This magnetic body 6
A is arranged so that one end thereof contacts one pole of the magnetic pole 5a, for example, the S pole. Therefore, the magnetic substance 6A has a polarity of S. The magnet 5A and the magnetic body 6A constitute magnetic field generating means.

Thus, the magnetic sensitive surface 10b of the GMR element 10 is
The magnetic pole 6a of the magnet 5A and the magnetic substance 6A.
There will be substantially two poles with the polarity S of. With this structure, the magnetic field at the uneven portion when the magnetic body rotating body 2 rotates is as shown in FIG. In the figure, as shown in FIG. 12A, the GMR element 10 is the magnetic body rotating body 2.
, The magnetic field generated from the N pole of the magnetic pole 5a of the magnet 5A reaches the convex portion of the magnetic body rotating body 2 via the magnetically sensitive surface 10b of the GMR element 10, and is again perpendicular to the convex portion. S of the magnetic body 6A is passed through the magnetically sensitive surface 10b of the GMR element 10.
On the other hand, when the GMR element 10 faces the concave portion of the magnetic body rotating body 2 as shown in FIG. 12B, the magnetic field generated from the N pole of the magnetic pole 5a of the magnet 5A becomes Most of the distribution reaches the S pole of the magnetic body 6A immediately via the magnetically sensitive surface 10b of the GMR element 10.

Here, the GMR element 10 is the magnetic body rotating body 2.
12 (a) of FIG. 12, the magnetic field strength is large because a magnetic field almost perpendicular is applied to the entire magnetic sensitive surface 10b of the GMR element 10, and the GMR element 1
When 0 is opposed to the concave portion of the magnetic body rotating body 2 ((b) of FIG. 12), a line perpendicular to the magnetic body rotating body 2 is drawn from the center (of the magnetic pole 5a) of the magnet 5A indicated by the alternate long and short dash line. The angle θ ₂ formed with the magnetic field is large because the magnetic field from the N pole of the magnetic pole 5a immediately reaches the S pole at one end of the magnetic body 6A, and as a result, the magnetic field strength also increases. Therefore, by the magnet 5A, GM
The amount of change in the magnetic field applied to the R element 10 due to the uneven portion of the magnetic body rotating body 2 is large.
The amount of change in the magnetic field of the magnetic sensitive surface 10b is also large, that is, the change in the resistance value of the magnetoresistive pattern is large.

As described above, also in the present embodiment, by arranging the magnet and the magnetic body so that the polarity N of the magnet and the polarity S at one end of the magnetic body are substantially two poles, the GMR element becomes a magnetic body. When facing the convex portion of the rotating body, a magnetic field almost perpendicular to the magnetic sensitive surface of the GMR element is applied, and when facing the concave portion of the magnetic rotating body, the magnetic field parallel to the magnetic sensitive surface of the GMR element. Is applied. As a result, the amount of change in the applied magnetic field on the magnetically sensitive surface of the GMR element is larger than in the case of the conventional arrangement in which a magnet having one magnetic pole is arranged, and the change in the magnetic field corresponding to the uneven portion of the magnetic body rotating body is accurately performed. Therefore, it becomes possible to detect efficiently, and a stable and accurate signal can be obtained. Further, since the magnetic body is used as the magnetic flux guide, the cost is low. Note that, in the above description, the polarity of the magnet is the N pole, but the same effect can be obtained with the opposite S pole.

Fifth Embodiment 13 is a configuration diagram showing a fifth embodiment of the present invention. In FIG. 1, FIG.
The same reference numerals are given to the portions corresponding to those in FIG. 4 for description. In the first embodiment, the magnets are arranged so that the polarities of the magnets are S, N, S or N, S, N. However, in the present embodiment, the magnet has one pole and is located on the side of the magnetic pole. A magnetic body serving as a magnetic flux guide is arranged in parallel with this in a spaced relationship. That is, as shown in FIG. 13, instead of the magnet 5 described above, a magnet 5A having one magnetic pole 5a is provided.
A magnetic body 6B having a predetermined shape, for example, a rod shape, is arranged at a side portion of A and is separated from the side portion.

Thus, the magnetic sensitive surface 10b of the GMR element 10
One pole having the polarity N of the magnetic pole 5a of the magnet 5A and one end of the magnetic body 6B are present facing each other. The magnet 5A and the magnetic body 6B substantially constitute magnetic field generating means. With this configuration, the magnetic field at the uneven portion when the magnetic body rotating body 2 rotates is as shown in FIG. In the figure, as shown in FIG. 14A, the GMR element 10 is the magnetic body rotating body 2.
, The magnetic field generated from the N pole of the magnetic pole 5a of the magnet 5A reaches the convex portion of the magnetic body rotating body 2 via the magnetically sensitive surface 10b of the GMR element 10, and is again perpendicular to the convex portion. When the distribution reaches the one end of the magnetic body 6B through the magnetically sensitive surface 10b of the GMR element 10, while the GMR element 10 faces the concave portion of the magnetic body rotating body 2 as shown in FIG. Most of the magnetic field generated from the N pole of the magnetic pole 5a of the magnet 5A has a distribution that reaches the one end of the magnetic body 6B immediately via the magnetically sensitive surface 10b of the GMR element 10.

Here, the GMR element 10 is the magnetic body rotor 2.
14 (a) in FIG. 14, the magnetic field strength is large because a substantially perpendicular magnetic field is applied over the entire magnetic sensitive surface 10b of the GMR element 10, and the GMR element 1
When 0 is opposed to the concave portion of the magnetic body rotating body 2 ((b) of FIG. 14), a line is drawn vertically from the center (of the magnetic pole 5a) of the magnet 5A shown by the alternate long and short dash line to the magnetic body rotating body 2. The angle θ ₂ formed with the magnetic field is large because the magnetic field from the N pole of the magnetic pole 5a immediately reaches one end of the magnetic body 6B, and as a result, the magnetic field strength also increases. Therefore, the amount of change in the magnetic field applied to the GMR element 10 by the magnet 5A is large due to the uneven portion of the magnetic body rotating body 2, and therefore the amount of change in the magnetic field of the magnetic sensitive surface 10b of the GMR element 10 is also large, that is, The change in the resistance value of the magnetoresistive pattern becomes large.

As described above, also in the present embodiment, the GMR element is opposed to the convex portion of the magnetic body rotating body by arranging so that the polarity N of the magnet and the one end of the magnetic body have substantially two poles. In this case, when a substantially perpendicular magnetic field is applied to the magnetically sensitive surface of the GMR element and the GMR element faces the concave portion of the magnetic body rotating body,
A parallel magnetic field is applied to the magnetically sensitive surface of the GMR element. As a result, the amount of change in the applied magnetic field on the magnetically sensitive surface of the GMR element is larger than in the case of the conventional arrangement in which a magnet having one magnetic pole is arranged, and the change in the magnetic field corresponding to the uneven portion of the magnetic body rotating body is accurately performed. Therefore, it becomes possible to detect efficiently, and a stable and accurate signal can be obtained. Further, since the magnetic body is used as the magnetic flux guide, the cost is low. Note that, in the above description, the polarity of the magnet is the N pole, but the same effect can be obtained with the opposite S pole.

Embodiment 6 FIG. 15 to 18 show Embodiment 6 of the present invention when the present device is applied to an internal combustion engine as an example. FIG. 15 is a configuration diagram showing the whole thereof, and FIG. 16 is a detection device main body and a magnetic body. 1 is a perspective view showing the positional relationship of the rotating bodies, FIG. 17 is a perspective view showing the main body of the detection device, and FIG.
Reference numeral 8 is an internal configuration diagram thereof. In the figure, the detection device main body 50 is provided in the vicinity of the internal combustion engine 60, and the rotating shaft 51 utilizing the crank shaft, cam shaft, etc. is provided with at least one or more irregularities as a signal plate. Two magnetic body rotating bodies 52 are provided so as to rotate in synchronization with this. Further, the control unit 61 is connected to the circuit section of the detection device main body 50, and
It is connected to a throttle valve 63 provided in an intake pipe 62 of the internal combustion engine 60.

The detector main body 50 is arranged near the internal combustion engine 60 so that the magnetic sensitive surface of the GMR element in the detector main body 50 faces the magnetic body rotating body 52. As shown in FIG. 17, the detection device main body 50 includes a housing 53 and a mounting portion 54 made of resin or a non-magnetic material,
From the bottom of the housing 53, terminals 55 such as power supply terminals, ground terminals, and output terminals using lead wires for input and output are taken out. Inside the housing 53, as shown in FIG. 18, a substrate 56 on which the circuit as described in FIG. 3 is arranged.
The GMR element 10 and the GMR element 57 and the magnet 58 corresponding to the magnet 5, for example, are mounted on a part of the substrate 56, respectively.

Next, the operation will be described. Now, when the magnetic body rotating body 52 rotates in synchronization with the rotation of the rotating shaft 51 due to the startup of the internal combustion engine 60, the magnetic field of the magnetic sensitive surface of the GMR element 57 in the detection device body 50 changes corresponding to the unevenness. However, the resistance value also changes. Then, the difference in the midpoint voltage of the Wheatstone bridge circuit composed of the GMR element 57 and the like is amplified by the differential amplifier circuit, and the output thereof is compared with the reference value by the comparison circuit to become the signal of "O" or "1". The converted signal is further waveform-shaped by the waveform-shaping circuit and supplied to the control unit 61 as an "O" or "1" signal. As a result, the control unit 61 can know the rotation angle and the rotation speed of the crankshaft and the camshaft corresponding to each cylinder of the internal combustion engine 60.
Then, the control unit 61 controls the output of the detection device, that is, the signal of “O” or “1” and the throttle valve 6
A control signal is formed based on the opening degree information and the like from 3, and the control signal controls the ignition timing of an ignition plug (not shown), the injection timing of a fuel injection valve, and the like.

In the above example, a lead wire is used as the input / output terminal 55 for the detection device main body 50, but as shown in FIG. May be. in this case,
The terminal 55 is incorporated in the connector 59, and the connector 5
When 9 is inserted into the housing 53 side, the terminal 55 is connected to the circuit portion of the substrate 56. This allows
It is easy to handle, structurally simple, and easy to assemble the device.

As described above, in the present embodiment, since the magnets arranged so that the polarities thereof have a plurality of poles with respect to the magnetic sensitive surface of the GMR element, the magnetic field applied to the magnetic sensitive surface of the GMR element is mounted. The amount of change in the magnetic field is large, and changes in the magnetic field corresponding to the irregularities of the magnetic body rotating body can be detected accurately and efficiently,
As a result, the rotation angle (rotation speed) of the crankshaft and camshaft of the internal combustion engine can be accurately detected using a small and inexpensive detection device, fine control is possible, and the mountability on the internal combustion engine can be improved. It is easy to install and is advantageous in terms of space.

Embodiment 7. 20 shows Embodiment 7 of the present invention. (A) of FIG. 20 is a perspective view showing the positional relationship between the detection device main body and the magnetic rotating body, and (b) of FIG. 20 is a side view thereof. is there. In the figure, parts corresponding to those in FIG. 16 are designated by the same reference numerals, and detailed description thereof will be omitted. In each of the above-described embodiments, the detection device body is provided in the direction perpendicular to the rotation axis, but in the present embodiment, the detection device body is provided in the direction coaxial with the rotation axis. That is, as shown in (a) of FIG. 20, the detection device body 50 is provided coaxially with the rotation shaft 51, and as shown in (b) of FIG. It is arranged so as to face the magnetically sensitive surface of the GMR element of the detection device body 50.

Thus, in the present embodiment, the same effect as in the sixth embodiment can be obtained, and further, in the present embodiment, the main body of the detection device can be arranged in the rotation axis direction, so that the rotation axis is substantially the same. The space can be shared, the shape of the device does not become large in the radial direction, and the miniaturization can be further improved.

Embodiment 8. 21 and 22 show Embodiment 8 of the present invention. FIG. 21 is a side sectional view thereof, and FIG. 22 is a schematic view of a detection device main body. In the figure, parts corresponding to those in FIGS. 16 and 18 are designated by the same reference numerals, and detailed description thereof will be omitted. In each of the above-described embodiments, the GMR element of the detection device main body and the magnetic rotating body are arranged in a state of being separated from each other with a predetermined gap.
In the present embodiment, the magnetic rotating body is arranged so as to be sandwiched between the GMR element of the detection device main body and the magnet with a predetermined gap.

The detection device main body 50A includes a housing 70 made of, for example, a resin or a non-magnetic material, and the housing 7.
The GMR element 10 described above provided in the cavity 70a
Cover 71 for protecting a considerable GMR element 57 and the like
And a mounting portion 74, and the cavity 70a in the housing 70 is provided with a substrate (not shown) on which the circuit as described in FIG. 3 is arranged, and the GMR element 57 is provided in a part of this substrate. It will be installed. The GMR element 57 has a terminal 72.
Are electrically connected to each other, and the terminal 72 extends to the bottom through the inside of the detection device main body 50A, and terminals 73 such as a power supply terminal, a ground terminal, an output terminal, etc. using lead wires for input and output thereto. Is connected and taken out. The magnet 5 is provided below the space 70b on the side surface of the housing 70 so as to face the magnetically sensitive surface of the GMR element 57 in the space 70b.
8 is provided, and the magnetic body rotating body 52 is provided such that at least the uneven portion of the magnetic body rotating body 52 that rotates in synchronization with the rotating shaft 51 passes between the GMR element 57 and the magnet 58.
Is arranged.

With such a structure, the magnet 5
8, the magnetic path passing through the magnetic body rotating body 52 and the GMR element 57 is substantially formed, and the magnetic field from the magnet 58 is generated when the concave portion of the magnetic body rotating body 52 is located between the GMR element 57 and the magnet 58. Is applied to the magnetically sensitive surface of the GMR element 57 as it is, while the magnetic field from the magnet 58 flows toward the magnetic body rotating body 52 in a state where the convex portion of the magnetic body rotating body 52 is positioned, and the GMR element is substantially. It cannot be applied to the magnetic sensitive surface of 57.
In other words, this is substantially the same as the state in which at least a part of the magnetic body rotating body 52 is composed of a magnet, and in this case, therefore, the magnetic body rotating body is rotated from the moment the power is supplied to the detection device. A so-called power-on function for obtaining an accurate signal corresponding to the unevenness of the body 52 can be obtained.

In the above example, the magnet 58 is provided below the space 70b on the side surface of the housing 70 so as to face the magnetically sensitive surface of the GMR element 57 in the space 70b. As shown in FIG.
A core 75 may be provided between the two to form a magnetic circuit. As a result, the magnet 58-the magnetic body rotating body 52-
GMR element 57-magnetic body rotating body 52-core 75-magnet 5
The closed magnetic circuit of 8 is substantially formed, a more reliable magnetic circuit is established, and the detectability is improved.

Thus, in the present embodiment as well, the same effect as that of the sixth embodiment can be obtained, and further, in the present embodiment, it is necessary to consider the positioning of the magnetic rotating body between the GMR element and the magnet. However, the power-on function can be obtained.

Embodiment 9 In each of the above-described embodiments, the magnetic body moving body as the magnetic field change imparting means is described as a magnetic body rotating body that rotates in synchronization with the rotation axis, but the same applies to a linearly displaced moving body. It can be applied and has the same effect. In this case, for example, application to detection of the valve opening degree of the EGR valve in the internal combustion engine or the like can be considered. Further, in the above-described Embodiments 6 to 8, the case where the magnetic field generating means in the form of the first embodiment is used has been described, but the form in the second to fifth embodiments may be used. Produce the effect of. Also,
In each of the above-described embodiments, the GMR is used as the magnetic detection element.
Although the case of the element has been described, any other element such as an MR element may be used as long as it is an element capable of magnetic detection.

[0060]

As described above, according to the first aspect of the present invention, the magnetic field generating means having a plurality of magnetic poles for generating a magnetic field and the magnetic field generating means are arranged with a predetermined gap therebetween. Since the magnetic field change applying means for changing the magnetic field generated by the magnetic field generating means and the magnetic detecting element whose resistance value changes according to the magnetic field changed by the magnetic field change applying means are provided, There is an effect that the change amount of the applied magnetic field on the surface is large, the detection can be performed efficiently, a stable and accurate signal can be obtained, and the detection accuracy can be improved.

According to a second aspect of the present invention, in the first aspect of the invention, the magnetic field generating means is composed of a magnet and a magnetic flux guide having a polarity opposite to that of the magnet. Is increased, and highly accurate detection is possible.

In the detection device according to the third aspect of the present invention, since part of the magnet is used as the magnetic flux guide in the second aspect of the invention, the magnetic field strength applied to the magnetic detection element can be reliably increased. There is an effect that more accurate detection becomes possible. .

According to the invention of claim 4, in the invention of claim 2, since the magnetic body is used as the magnetic flux guide, there is an effect that the cost of the device can be reduced.

In the detection device according to the invention of claim 5, in the invention of claim 1, the magnetic field change imparting means is composed of a magnetic body moving body having at least one concavo-convex, so that even small irregularities can be detected. There is an effect that the detection accuracy can be further improved.

A detection apparatus according to a sixth aspect of the present invention is the detection apparatus according to any one of the first to fifth aspects, wherein a bridge circuit using a magnetic detection element on at least one side and signal processing of the output of the bridge circuit are provided. Since the signal processing means is provided, the change in the magnetic field can be detected in a stable manner, and the resistance change amount of the magnetic detection element also increases in a stable manner, so that the output of the signal processing means also increases and "0" in this signal processing means. ”
Alternatively, the margin with respect to the determination level at the time of conversion into the signal of "1" is increased, the resistance against external noise is increased, and a stable signal can be obtained.

According to a seventh aspect of the present invention, in the detecting device according to any one of the first to sixth aspects, the magnetic body moving body is a magnetic body rotating body that rotates in synchronization with the rotation axis. There is an effect that it is possible to reliably detect a change in the magnetic field due to the rotation of the rotating body.

According to an eighth aspect of the present invention, there is provided a detection device according to the seventh aspect, which comprises a detection device main body including at least a magnetic detection element, and the magnetic rotating body is mounted on a crankshaft or a camshaft of an internal combustion engine. Since the main body of the detection device is arranged in the vicinity of the internal combustion engine so that the magnetic rotating body faces the magnetic detecting element, it is possible to accurately detect the rotation angle (rotation speed) of the crankshaft and camshaft of the internal combustion engine, and to perform fine control. Further, there is an effect that it is possible to improve the mountability to the internal combustion engine, the mounting is easy, the space is advantageous, and the device can be made compact.

According to a ninth aspect of the present invention, in the eighth aspect of the invention, since the detection device main body is arranged in the rotation axis direction with respect to the magnetic body rotating body, the space of the rotation axis is substantially shared. Therefore, there is an effect that the size of the device does not become large in the radial direction and the size reduction can be further promoted.

The detector according to the invention of claim 10 is
In the invention of claim 9, the main body of the detection device includes a housing containing at least a magnetic detection element, and the magnetic body rotating body is provided with a space formed on a side surface of the housing in which at least a peripheral portion of the magnetic body rotating body is magnetic. Since it is arranged so as to face the detection element, a magnetic path passing through the magnetic body rotating body and the magnetic detection element is substantially formed, and at least a part of the magnetic body rotating body is composed of a magnet. In this state, the output corresponding to the rotation angle of the magnetic rotating body can be accurately obtained from the moment the power is supplied to the detection device, and the power-on function can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a detection device according to the present invention.

FIG. 2 is a block diagram showing a circuit configuration of the detection device according to the first embodiment of the present invention.

FIG. 3 is a circuit diagram showing an example of a specific circuit configuration of FIG. 2;

FIG. 4 is an enlarged perspective view showing a GMR element and a magnet according to the first embodiment.

FIG. 5 is a diagram showing the unevenness of the magnetic body rotating body and the distribution of the magnetic field between the GMR elements in the first embodiment.

FIG. 6 is a waveform diagram for explaining the operation of FIG.

FIG. 7 is an enlarged perspective view showing a GMR element and a magnet in a second embodiment of the detection device according to the present invention.

FIG. 8 is a diagram showing unevenness of a magnetic body rotating body and a magnetic field distribution between GMR elements according to the second embodiment.

FIG. 9 is an enlarged perspective view showing a GMR element and a magnet in a third embodiment of a detection device according to the present invention.

FIG. 10 is a diagram showing unevenness of a magnetic rotating body and a magnetic field distribution between GMR elements according to the third embodiment.

FIG. 11 is an enlarged perspective view showing a GMR element and a magnet in a fourth embodiment of the detection apparatus according to the present invention.

FIG. 12 is a diagram showing the magnetic field distribution between the concave and convex portions of the magnetic rotating body and the GMR element according to the fourth embodiment.

FIG. 13 is an enlarged perspective view showing a GMR element and a magnet in a fifth embodiment of the detection apparatus according to the present invention.

FIG. 14 is a diagram showing the unevenness of a magnetic rotating body and the distribution of a magnetic field between GMR elements in the fifth embodiment.

FIG. 15 is a configuration diagram showing a sixth embodiment of a detection device according to the present invention.

FIG. 16 is a perspective view showing an arrangement relationship between a detection device main body and a magnetic rotating body in a sixth embodiment of the detection device according to the present invention.

FIG. 17 is a perspective view showing a detection device body according to a sixth embodiment of the detection device of the present invention.

FIG. 18 is an internal configuration diagram of a detection device body in the sixth embodiment of the detection device according to the present invention.

FIG. 19 is a side sectional view showing another example of the detection device body in the sixth embodiment of the detection device according to the present invention.

FIG. 20 is a configuration diagram showing a seventh embodiment of a detection device according to the present invention.

FIG. 21 is a side sectional view showing an eighth embodiment of the detection device according to the present invention.

FIG. 22 is a perspective view showing a detection device main body according to the eighth embodiment of the detection device of the present invention.

FIG. 23 is a side sectional view showing another example of the detection device according to the eighth embodiment of the present invention.

FIG. 24 is a configuration diagram showing a conventional detection device.

FIG. 25 is an enlarged perspective view showing an MR element and a magnet in a conventional detection device.

FIG. 26 is a diagram showing the magnetic field distribution between the MR element and the concavities and convexities of the magnetic rotating body in the conventional detection device.

FIG. 27 is a schematic diagram showing a circuit configuration of a conventional detection device.

[Explanation of symbols]

1,51 rotating shaft, 2,52 magnetic rotating body, 5,5
A, 5B magnets, 5a-5c magnetic poles, 6, 6A, 6B
Magnetic material, 10, 10A to 10D GMR element, 11 Wheatstone bridge circuit, 12 Differential amplifier circuit, 13
Comparison circuit, 14 waveform shaping circuit, 50, 50A detection device main body, 53 housing.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Wataru Fukui 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Corporation (72) Inventor Yutaka Ohashi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Rishi Electric Co., Ltd.

Claims (10)

[Claims] 1. A magnetic field generating means having a plurality of magnetic poles for generating a magnetic field, and a magnetic field change imparting means arranged to have a predetermined gap from the magnetic field generating means and changing the magnetic field generated by the magnetic field generating means. A detection device comprising: a magnetic field detection element, and a magnetic detection element whose resistance value changes according to the magnetic field changed by the magnetic field change applying means. 2. The magnetic field generating means comprises a magnet and a magnetic flux guide having a polarity opposite to that of the magnet.
The detection device described. 3. The detection device according to claim 2, wherein a part of the magnet is used as the magnetic flux guide. 4. The detection device according to claim 2, wherein a magnetic material is used as the magnetic flux guide. 5. The detection device according to claim 1, wherein the magnetic field change imparting means is constituted by a magnetic body moving body having at least one unevenness. 6. A bridge circuit using the magnetic detection element on at least one side, and signal processing means for signal-processing the output of the bridge circuit.
5. The detection device according to any one of 5. 7. The magnetic body moving body is a magnetic body rotating body that rotates in synchronization with a rotation axis.
The detection device according to any one of to 6. 8. A detection device main body including at least the magnetic detection element, wherein the magnetic body rotating body is mounted on a crankshaft or a cam shaft of an internal combustion engine so that the magnetic body rotating body faces the magnetic detection element. The detection device according to claim 7, wherein the detection device main body is disposed in the vicinity of the internal combustion engine. 9. The detection device main body is arranged in the rotation axis direction with respect to the magnetic body rotating body.
The detection device described. 10. The detection device main body includes a housing containing at least the magnetic detection element, and the magnetic body rotating body is provided in a space formed on a side surface of the housing, at least a peripheral portion of the magnetic body rotating body. 10. The detection device according to claim 9, wherein the magnetic detection element is arranged so as to face the magnetic detection element.