JP2001249029A - Rotation detection sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotation detection sensor which enables accurate detection of angles regardless of any smaller rotation member. SOLUTION: There are arranged a rotary plate 12 which is supported rotatably on a rotating shaft 14 with a plurality of slits 15 formed radially, a second bias magnet 16 and a magnetic resistance element 17 arranged respectively on both sides sandwiching the slits 15 of the rotary plate 12 and a first bias magnet 18 arranged beside the magnetic resistance element 17. The magnetic poles closer to the rotary plate 12 of the second and first bias magnets 16 and 18 are S and N poles respectively. As the slits 15 are positioned between the second bias magnet 16 and the magnetic resistance element 17, the direction of the magnetic flux Z of the first bias magnet 18 changes and the changes are detected by the magnetic resistance element 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation detection sensor, and more particularly, to a rotation detection sensor having a magnetic detection element.

[0002]

2. Description of the Related Art Conventionally, there is a rotation detecting sensor for detecting the rotation of a rotating body as shown in FIGS. 7 (a) and 7 (b). The rotation detection sensor 51 includes a rotation plate 52 made of an iron plate and a detection unit main body 53. The rotating plate 52 rotates about its axis O with rotation of a rotating shaft 54 such as a steering shaft of the vehicle. On the entire circumference around the outer circumference of the rotary plate 52,
A plurality of radial slits 55 centering on the axis O are formed at predetermined pitch intervals.

[0003] The detection unit main body 53 is disposed close to a slit 55 formed in the rotary plate 52. The detection unit main body 53 has a bias magnet 57 disposed opposite to the rotating plate 52 and arranged in a predetermined direction.
And a magnetic sensing element 58 for detecting a change in magnetic flux of the bias magnet 57 are embedded. The rotation detecting sensor 51 detects that the direction of the magnetic flux of the bias magnet 57 has been changed when the slit 55 that moves integrally with the rotating rotary plate 52 passes through a position corresponding to the detecting unit main body 53. The detection is performed by the magnetic sensing element 58.

[0004]

However, in order to reduce the size of the rotation detecting sensor 51 having such a configuration, it is conceivable to reduce the diameter of the rotating plate 52. However, in order to reduce the diameter of the rotary plate 52 without reducing the number of the slits 55 of the rotary plate 52, the distance between the adjacent slits 55 must be reduced and the groove width of the slit 55 must be reduced. When the detection unit main body 53 tries to detect the slit 55 of the rotating plate 52 using such a rotating plate 52, the undulation of the change in magnetic flux is reduced by the decrease in the distance between the detection angles, and the accurate angle It was difficult to detect.

Accordingly, the present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a rotation detection sensor that can accurately detect an angle even if a rotating member is small.

[0006]

According to a first aspect of the present invention, there is provided an apparatus having a plurality of slits which are rotatably supported and arranged at predetermined pitch intervals along a rotation direction. A rotating member, a first magnet for bias arranged on one side of the rotating member and arranged in a predetermined direction with respect to a slit of the rotating member, and also on one side of the rotating member. A magnetic sensing element that is arranged to face the slit and detects the first magnet, and the first magnet is arranged on the other side of the rotating member so as to sandwich the rotating member; A second magnet disposed in a predetermined direction with respect to the slit of the magnetic sensing element, wherein a change in magnetic flux of the first magnet caused by the second magnet according to the presence or absence of the slit accompanying rotation of the rotating member is provided by the magnetic sensing element. Detected by The gist of the door.

According to a second aspect of the present invention, in the rotation detecting sensor according to the first aspect, the second magnet is arranged such that a magnetic flux direction thereof substantially coincides with a direction passing through a slit of the rotating member. Is the gist.

According to a third aspect of the present invention, in the rotation detecting sensor according to the first or second aspect, the first magnet is disposed so as to be substantially perpendicular to the direction of the magnetic flux of the second magnet. That is the gist. (Operation) Therefore, according to the first aspect of the present invention, when the rotating member rotates and the magnetic sensing element and the slit face each other, the magnetic flux of the first magnet and the magnetic flux of the second magnet influence each other via the slit. Then, the magnetic flux changes. Then
The magnetic sensing element detects a change in magnetic flux of the first magnet. or,
When the rotating member rotates and the magnetic sensing element and the slit no longer face each other, the magnetic flux of the second magnet and the magnetic flux of the first magnet are separated by the rotating member, and the magnetic fluxes of both magnets do not affect each other. Change. Then, the magnetic sensing element detects a change in the magnetic flux of the first magnet. That is, compared to the case of a single magnet,
In the case of cooperation between the first magnet and the second magnet, a large change in magnetic flux due to the presence or absence of the slit can be obtained. Therefore, the first
In the case of cooperation between the magnet and the second magnet, a change in magnetic flux of the first magnet due to the presence or absence of the slit can be accurately obtained even if the groove width of the slit and the interval between the slits are small.

According to the second aspect of the invention, in addition to the function of the first aspect, when the magnetic sensing element and the slit face each other, the magnetic flux of the second magnet passes through the slit. I do. Then, the magnetic flux of the first magnet and the magnetic flux of the second magnet further influence each other. Then, the magnetic sensing element:
A change in the magnetic flux of the first magnet is detected more accurately.

According to the third aspect of the present invention, in addition to the operation of the first or second aspect, when the magnetic sensing element and the slit face each other, the magnetic flux of the first magnet and Since the magnetic flux of the second magnet and the magnetic flux of the second magnet affect each other at a substantially right angle, the magnetic flux of both magnets greatly changes in a direction perpendicular to the direction of the magnetic flux. Then, the magnetic sensing element detects a change in the magnetic flux of the first magnet more accurately.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment in which the present invention is embodied in a rotational position sensor will be described below with reference to FIGS.

As shown in FIGS. 1 and 2, a rotation position sensor 11 as a rotation detection sensor includes a disk-shaped rotation plate 12 as a rotation member made of an iron plate (magnetic material) and a detection unit main body 13.
It is composed of Note that the magnetic material of the present embodiment indicates a ferromagnetic material. The rotary plate 12 is formed to have a smaller diameter than the conventional rotary plate 52, and a rotary shaft 14 having an axis O is inserted and fixed at the center thereof. The rotating plate 12 rotates about its axis O with the rotation of the rotating shaft 14.

Radial slits 15 centering on the axis O are provided at predetermined pitch intervals around the entire outer periphery of the rotary plate 12, and the direction in which the slits 15 are provided is as follows.
It is formed so as to be substantially parallel to the axial direction of the axis O.
The number of the slits 15 is the same as the number of the slits 55 of the related art.
5 is formed narrower than the groove width. Further, the distance between the adjacent slits 15 is formed shorter than the distance between the adjacent slits 55 described above.

In the vicinity of the outer periphery of the rotary plate 12, a recess 13 is provided.
The detection unit main body 13 having a is fixed by a fixing member (not shown). The outer peripheral portion of the rotary plate 12 is inserted into the concave portion 13a of the detection unit main body 13, and the rotary plate 1
2 rotates, each slit 15 of the rotating plate 12 is
3a.

In the detection unit main body 13, the rotating plate 1
A magneto-resistive element 17 as a magnetic sensing element is buried in a portion located on one side of 2. The magnetoresistive element 17 is arranged close to and opposed to the slit 15 of the rotating plate 12. The detailed description of the magnetoresistive element 17 will be described later. Similarly, a first bias magnet 18 as a first magnet is buried inside the detecting portion main body 13 on the side of the magnetoresistive element 17 and close to the slit 15. The first
In the bias magnet 18, the north pole is proximal to the magnetoresistive element 17, the south pole is distal to the magnetoresistive element 17, and the direction of the magnetic flux of the first bias magnet 18 is the axial direction of the axis O. Are arranged so as to be substantially perpendicular to.

On the other hand, a portion of the detection unit main body 13 located on the other side of the rotary plate 12 is provided with a second magnet as a second magnet so as to be close to and opposed to the slit 15 of the rotary plate 12. A bias magnet 16 is embedded. The second bias magnet 16 is arranged so as to face the magnetoresistive element 17 with the rotating plate 12 interposed therebetween. The second bias magnet 16 has an S pole proximal to the rotating plate 12, an N pole distal to the rotating plate 12, and a second bias magnet 1.
6 are arranged so that the direction of the magnetic flux is substantially parallel to the axial direction of the axis O.

That is, the rotation of the rotating plate 12 causes the slit 15 to pass between the S pole of the second bias magnet 16 and the magnetoresistive element 17. The direction of the magnetic flux of the first bias magnet 18 and the direction of the magnetic flux of the second bias magnet 16 are substantially perpendicular to each other.

Next, the magnetoresistive element 17 will be described.
The magneto-resistive element 17 is a magneto-resistive element whose detection voltage changes according to the direction of the magnetic flux Z (see FIGS. 4 and 5) of the first bias magnet 18. Four resistors R1 to R having variable resistance values
4 is provided. As shown in FIG. 2, two resistors R
1 and R4 are arranged in the same arrangement direction, and the group of resistors R2 and R3 is the group of resistors R1 and R3.
4 are arranged in an arrangement direction orthogonal to the arrangement direction.

Note that the alternate long and short dash line m and the alternate long and short dash line n indicate the directions in which the resistors R1, R4 and the resistors R2, R3 are directed, respectively. The point at which the dashed-dotted lines m and n intersect is the base point P
And the bisector of the angle formed by the dashed lines m and n passing through the base point P is defined as the dashed line S. In the present embodiment, the clockwise direction and the counterclockwise direction from the dash-dotted line S around the base point P are defined as the forward direction and the counterclockwise direction, respectively.

Each of the resistors R1 to R4 is formed by forming a Ni—Co thin film in a zigzag shape on the substrate, that is, in a polygonal line shape. The resistors R1 to R4 are set to have the same resistance under the same temperature atmosphere. In addition,
The resistors R1 to R4 have sensitivity temperature characteristics in which the sensitivity changes when the ambient temperature increases. In this sensitivity temperature characteristic, it is preferable that the rate of change in sensitivity temperature and the rate of change in resistance temperature match.

When the magnetic flux Z is directed in the opposite direction, the resistors R1 and R4 are arranged to have a large resistance value, and the resistors R2 and R3 are arranged to have a small resistance value. When the direction of the magnetic flux Z is the forward direction, the resistors R1 and R4 are arranged such that the resistance is small, and the resistors R2 and R3 are arranged such that the resistance is large. Therefore, the magnitudes of these resistance values alternately occur according to the change in the magnetic flux Z.

The resistors R1 to R4 are connected to form a four-terminal bridge circuit B as a bridge circuit as shown in FIG. The resistor R1 and the resistor R2
Is connected to the non-inverting input terminal of the comparator CP provided on the substrate, and the connection point (middle point) b between the resistor R3 and the resistor R4 is connected to the inverting terminal of the comparator CP. Connected to input terminal.

The comparator CP and the four-terminal bridge circuit B constitute a detection circuit DC. Resistors R1, R4 constituting a bridge circuit B of the detection circuit DC
Is such that when the direction of the magnetic flux Z is on the positive side, the potential at the midpoint a is at the H level. When the direction of the magnetic flux Z is on the opposite side, the potential at the middle point a is at the L level.

Next, the operation of the rotational position sensor 11 configured as in the present embodiment will be described with reference to FIGS. 4 and 5, for convenience of explanation, the detection unit main body 13
Is partially omitted, and the second bias magnet 16, the magnetoresistive element 17, and the first bias magnet 18 are exposed.

As shown in FIG. 4, the rotating plate 12 rotates,
If the slit 15 is not located between the second bias magnet 16 and the magnetoresistive element 17, the magnetic flux Z is hardly guided to the rotating plate 12, and the direction of the magnetic flux Z near the resistors R1 to R4. Is on the positive side. Then, the detection circuit D
The potential at the middle point a of C outputs an H-level potential.

On the other hand, as shown in FIG. 5, when the rotating plate 12 rotates and the slit 15 is located between the second bias magnet 16 and the magnetoresistive element 17, the second bias magnet 16 magnetic fluxes and the first bias magnet 1
8 affect each other. That is, the magnetic flux generated from the N pole of the first bias magnet 18 is drawn to the S pole of the second bias magnet 16 via the slit 15, and the magnetic flux is directed to the S pole of the second bias magnet 16.

In this state, the magnetic flux Z is attracted to the south pole of the second bias magnet 16, and the magnetic flux Z is applied to the resistors R1 to R1.
In the opposite direction near R4, the first bias magnet 1
Head for the 8th S pole. At this time, since the magnetic flux of the second bias magnet 16 and the magnetic flux of the first bias magnet 18 are substantially perpendicular to each other, the magnetic flux of the two magnets 16 and 18 greatly changes in a direction orthogonal to the direction of the magnetic flux. . Therefore, the magnetic flux Z tends to be in the opposite direction near the resistors R1 to R4. Then, the potential at the middle point a of the detection circuit DC outputs an L-level potential.

Thus, on both sides of the rotating plate 12,
If the second bias magnet 16 and the first bias magnet 18 are provided, and the magnetic poles on the side close to each other are arranged differently, for example, the slit 15
Even if the groove width is small and the distance between the slits 15 adjacent to each other is short, a large undulation of a change in magnetic flux can be obtained. The above operation is performed alternately and repeatedly during rotation of the rotating plate 12,
The potential of the middle point a is shaped by the comparator CP of the detection circuit DC into a waveform of a detection signal having a sharp rise and fall based on the middle point b on the side where the reference voltage is set.

Accordingly, the rotational position sensor 11 of the present embodiment
According to this, the following effects can be obtained. (1) In the present embodiment, the second bias magnet 1 is opposed to both sides of the position where the slit 15 of the rotating plate 12 passes.
6 and a magnetoresistive element 17, and a first bias magnet 18 is provided on a side of the magnetoresistive element 17. The south pole of the second bias magnet 16 is connected to the rotating plate 12 side and the first bias magnet 1
The N pole 8 is located on the magnetoresistive element 17 side.

The magnetic flux Z generated from the N pole of the first bias magnet 18 depends on whether or not the slit 15 is located between the second bias magnet 16 and the magnetoresistive element 17. A change occurs whether it is attracted to the poles or not. The change in the magnetic flux Z is detected by the magnetoresistive element 17. Therefore, the angle can be detected more accurately than when the magnetoresistive element 17 detects a change in magnetic flux due to a single magnet.

(2) In the present embodiment, since the second bias magnet 16 and the first bias magnet 18 on both sides of the rotary plate 12 are provided, the groove width where it is difficult to obtain a change in magnetic flux by a single magnet is narrow. Even if a rotary plate having a slit with a small distance between the two is used, the angle can be detected accurately. Therefore, the diameter of the rotating plate can be made smaller than that of the prior art without reducing the number of slits. As a result, the rotation position sensor 11 can be smaller than the rotation detection sensor 51.

(3) In the present embodiment, the direction of the magnetic flux of the second bias magnet 16 and the direction of the slit 15 are substantially the same. Therefore, when the slit 15 is located between the second bias magnet 16 and the magnetoresistive element 17, the magnetic flux generated from the N pole of the first bias magnet 18 is further drawn to the S pole of the second bias magnet 16. Work can be strengthened.

(4) In the present embodiment, the direction of the magnetic flux of the first bias magnet 18 and the direction of the magnetic flux of the second bias magnet 16 are substantially perpendicular to each other. Therefore, when the slit 15 is located between the second bias magnet 16 and the magnetoresistive element 17, the magnetic flux of the two magnets 16, 18 greatly changes in a direction perpendicular to the direction of the magnetic flux. Therefore, the magnetic flux Z of the first bias magnet 18 can be easily shifted in the opposite direction near the resistors R1 to R4.

The above embodiment may be modified and embodied in another embodiment as described below. -Although the rotating plate 12 of the above embodiment is formed of iron, it may be formed of a ferromagnetic material such as nickel, cobalt, and an alloy containing these. Further, the rotating plate 12 may be formed of an alloy including iron.

The rotary plate 12 of the above embodiment is made of iron, which is a magnetic material, but need not be made of a magnetic material. With such a configuration, the magnetic flux Z of the first bias magnet 18 is maintained in a state where the magnetic resistance element 17 and the slit 15 are not opposed to each other.
Since the magnetic flux Z is not guided to the rotating plate 12, the magnetic flux Z is more accurately directed to the positive direction, and the detection accuracy of the rotational position sensor 11 can be improved.

In the configuration of the above embodiment, the slit 15 of the rotary plate 12 may be changed so as to open to the outer peripheral edge of the rotary plate 12, as shown in FIG. Next, technical ideas other than the inventions described in the claims that can be grasped from the above embodiment and other embodiments will be described below together with their effects.

(A) The magnetic sensing element and the second magnet are arranged so as to face each other, and the first magnet is arranged so as to be close to the magnetic sensing element. 4. The rotation detection sensor according to any one of 3. With this configuration, when the magnetic sensing element and the slit face each other, the magnetic flux of the first magnet can be easily changed by the magnetic flux of the second magnet.

(B) The magnetic poles of the first magnet and the second magnet adjacent to the slit are different between the first magnet and the second magnet.
(B) The rotation detection sensor according to any one of (1) and (2). With this configuration, when the magnetic sensing element and the slit face each other, the magnetic flux of the first magnet and the magnetic flux of the second magnet are attracted to each other, whereby the magnetic flux of the first magnet can be changed.

(C) The magnetic pole of the first magnet adjacent to the slit is an N pole, and the magnetic pole of the second magnet adjacent to the slit is an S pole. 3, one of (a) and (b)
A rotation detection sensor according to the item. With this configuration, when the magnetic sensing element and the slit face each other, the magnetic flux generated from the N pole of the first magnet is attracted to the S pole of the second magnet, thereby changing the magnetic flux of the first magnet. Can be increased.

[0040]

According to the first to third aspects of the present invention, the magnetic sensing element detects whether or not the magnetic flux of the first magnet and the magnetic flux of the second magnet influence each other. In addition, the angle detection can be performed more accurately than when the magnetic flux change of the single magnet is detected by the magnetic detection element. Further, even if the groove width of the slit and the interval between the slits are small, the change of the magnetic flux of the first magnet due to the presence or absence of the slit becomes large due to the presence of the second magnet.
A change in magnetic flux can be accurately detected, and as a result, the size of the rotating plate and, consequently, the size of the rotation detection sensor itself can be reduced as compared with a rotation detection sensor using a single magnet.

According to the second aspect, the rotation can be detected with higher accuracy. According to the third aspect of the invention, the rotation can be detected with higher accuracy.

[Brief description of the drawings]

FIG. 1 is a perspective view of a rotation position sensor according to an embodiment.

FIG. 2 is a partially enlarged sectional view of a rotation position sensor according to the embodiment.

FIG. 3 is an electric circuit of a detection circuit according to the embodiment.

FIG. 4 is an explanatory diagram showing the operation of the rotation position sensor according to the embodiment.

FIG. 5 is an explanatory diagram showing the operation of the rotation position sensor according to the embodiment.

FIG. 6 is a front view showing a rotating plate according to another embodiment.

7A is a partial cross-sectional view of a rotation position sensor according to the related art, and FIG. 7B is a front view of a rotating plate according to the related art.

[Explanation of symbols]

11 ... Rotation position sensor as rotation detection sensor, 12 ...
Disk-shaped rotating plate as rotating member, 15 ... slit, 1
6 ... second bias magnet as second magnet, 17 ... magnetic resistance element as magnetic sensing element, 18 ... first bias magnet as first magnet.

Continued on the front page (72) Inventor Tomoya Eguchi 3-260 Toyota, Oguchi-machi, Niwa-gun, Aichi Prefecture Inside Tokai Rika Electric Works, Ltd. F term in Rika Electric Works (reference) 2F063 AA35 BA08 CA34 DA05 EA03 GA52 GA69 KA02 KA04 2F077 CC02 NN02 NN21 NN23 PP14 QQ02 VV02

Claims (3)

[Claims] A rotating member having a plurality of slits rotatably supported and arranged at predetermined pitch intervals along a rotating direction; and a slit of the rotating member arranged on one side of the rotating member. A first magnet for bias arranged in a predetermined direction with respect to the magnet; and a magnet for detecting the first magnet, which is also arranged on one side of the rotating member so as to face the slit. A sensing element, and the first magnet includes a second magnet disposed on the other side of the rotating member so as to sandwich the rotating member, and a second magnet disposed in a predetermined direction with respect to a slit of the rotating member. Depending on the presence or absence of the slit accompanying the rotation of the rotating member, the second
A rotation detection sensor configured to detect a change in magnetic flux of a first magnet by a magnet with the magnetic detection element. 2. The rotation detecting sensor according to claim 1, wherein the magnetic flux direction of the second magnet is arranged so as to substantially coincide with a direction passing through a slit of the rotating member. 3. The rotation detection sensor according to claim 1, wherein the first magnet is disposed so as to be substantially perpendicular to a direction of a magnetic flux of the second magnet.