JP2001133285A - Revolution detection sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a revolution detection sensor provided with a comparison circuit for shaping wave form based on a threshold set to stably be 50 vs 50 duty ratio in the case of a large output variation due to temperature characteristics. SOLUTION: A revolution member arranging each magnetic path changing piece in the revolution direction so that the ratio of length in the revolution direction of magnetic path changing pieces 6a to 6c and the length of spaces 7a to 7c in the revolution direction is set to be 40 vs 60, and a first to third magnetic detector 13 to 15 arranged in a specific direction to the revolution member, are provided. An output circuit for obtaining waveform output in detecting the revolution motion of the magnetic path changing pieces 6a to 6c is constituted and is connected to a comparison circuit for shaping wave form based on a threshold setting the output signal of the output circuit to be 1/4 of output change width and duty ratio to be 50 vs 50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art As a rotation detecting sensor, the applicant of the present invention has a ratio of the distance between the length of the magnetic path changing piece and the length of the magnetic path changing piece in the direction of rotation of the rotating surface of the rotating plate. 5
Each magnetic path changing piece is erected so as to be 0:50, and a bias magnet and a magnetic resistance for detecting the bias magnet are disposed to face the rotating plate and arranged in a predetermined direction. Has proposed a rotation detection sensor having an element. The rotation detection sensor is configured to detect, by a magnetoresistive element, that the direction of the magnetic flux of the bias magnet is changed by a magnetic path changing piece that moves together with the rotating plate being rotated.

In a rotation detection sensor (rotation angle sensor) for detecting a rotation angle based on a change in the direction of the magnetic flux, a saturation output is obtained when the change in the magnetic flux is 90 °, for example.

Conventionally, a signal detected by the magnetoresistive element is input to a comparison circuit, and the comparison circuit sets a threshold (threshold) at a position to be detected, and sets a predetermined duty ratio by the threshold. I am getting it. That is, this threshold is set to about half of the sensor output in order to make the duty ratio 50:50. The threshold is set to this value when the output fluctuation of the rotation detection sensor is small.
This is because the output change is the largest at a half position of the output, and therefore the duty ratio is most stable.

[0005]

However, in the above-mentioned rotation detecting sensor, if the output fluctuates greatly due to temperature characteristics, setting the threshold value to a half of the normal position as in the prior art, on the contrary, will reduce the duty ratio. It changes greatly. Therefore, it is conceivable to stabilize the duty ratio by setting the threshold to 1/5 to 1/3 of the output fluctuation. Then, the duty ratio is stabilized, but the duty ratio does not become 50:50.

Therefore, if the duty ratio is not 50:50, the algorithm of the program for detecting and controlling the rotational position on the premise of using the duty ratio becomes complicated and long. As a result, the time required for each operation increases, and there is a problem that detection in real time becomes difficult.

An object of the present invention is to provide a stable duty ratio of 50: 5 even when there is a large output fluctuation due to temperature characteristics.
An object of the present invention is to provide a rotation detection sensor including a comparison circuit for shaping a waveform based on a threshold set to be zero.

[0008]

In order to achieve the above object, the invention according to claim 1 comprises a rotating member having a plurality of magnetic path changing pieces arranged at predetermined intervals in a rotational movement direction; A magnet disposed in a predetermined direction with respect to the member, and a plurality of magnetic sensing elements for detecting the magnets, a predetermined arrangement of a plurality of magnetic resistors constituting each of the magnetic sensing elements, By a predetermined electrical connection between the magnetoresistors,
In a rotation detection sensor that constitutes an output circuit that obtains a waveform output when detecting the rotational movement of the magnetic path changing piece, a ratio of an interval length of each magnetic path changing piece to a length of the magnetic path changing piece in a rotational movement direction. Are different.

According to a second aspect of the present invention, in the rotation detecting sensor according to the first aspect, a ratio of an interval length of each of the magnetic path changing pieces to a length of the magnetic path changing pieces in the rotational movement direction is 65.
The gist is that the magnetic path changing pieces are arranged so as to be 55 to 35:45.

According to a third aspect of the present invention, in the rotation detecting sensor according to the first or second aspect, the output circuit forms a waveform based on a threshold set to have a duty ratio of 50:50. The gist is that they are connected to a comparison circuit.

According to a fourth aspect of the present invention, in the rotation detection sensor according to the first or second aspect, the output circuit outputs an output signal of the rotation detection sensor from 1/5 to 1/1 of a normal output change width.
3 or 2/3 to 4/5 with a duty ratio of 50:
The gist is that it is connected to a comparison circuit that shapes a waveform based on a threshold value set to be 50.

According to a fifth aspect of the present invention, in the rotation detecting sensor according to any one of the first to fourth aspects, the plurality of magnetic resistors are generated by movement of the magnetic path changing piece. A first state in which the magnetic resistance increases in accordance with a change in the magnetic flux of the magnet, and a second state in which the magnetic resistance decreases.
Is arranged so as to alternately repeat the state of
When the magnetic flux changes, the two groups are arranged so as to be in opposite states to each other, and the output circuit is configured such that the magnetic resistors respectively belonging to the two groups are electrically connected. The gist is a bridge circuit.

According to a sixth aspect of the present invention, in the rotation detecting sensor according to any one of the first to fifth aspects, an interval between the magnetic path changing pieces and a rotation of the magnetic path changing pieces are provided. The gist is that the magnetic path changing pieces are arranged so that the length ratio in the moving direction is 60:40.

(Operation) According to the first aspect of the present invention,
The interval length between the magnetic path changing pieces and the length in the rotational movement direction of the magnetic path changing pieces are arranged differently. Then, the output circuit can obtain a waveform output corresponding to the ratio of the interval length of the magnetic path changing piece to the length of the magnetic path changing piece in the rotational movement direction.

According to the invention described in claim 2, according to claim 1
In addition to the operation described in the above, the ratio between the interval length of each magnetic path changing piece and the length of the magnetic path changing piece in the rotational movement direction is 65 to 55:35.
The magnetic path changing pieces are arranged so as to be 45. Then, the output circuit can obtain an output having a waveform corresponding to a ratio of 65 to 55:35 to 45.

According to the third aspect of the present invention, the first aspect is provided.
Alternatively, in addition to the function of the invention described in claim 2, the output circuit is connected to a comparison circuit that shapes a waveform based on a threshold set to have a duty ratio of 50:50. Then, a signal having a duty ratio of 50:50 is input to the comparison circuit.

According to the invention described in claim 4, according to claim 1,
In addition to the operation of the invention described in any one of claims 3 to 3, the output circuit outputs the output signal to 1/5 to 1/3 or 2/3 to 4 / of the normal output change width. 5 and
It is connected to a comparison circuit that shapes a waveform based on a threshold value set so that the duty ratio is 50:50.

Referring to FIG. 6 or FIG. 10 of an embodiment which will be described later, for example, 1/5 of the output change width W at normal time
In the case of １ ／ to 又 は or ／ to ／, the output waveform input from the output circuit to the comparison circuit is as indicated by α1 in FIG. 6 or FIG. At this time, when the output fluctuates, the waveform changes from α1 to α2 as shown in FIG.

However, the output change width W at normal time is 1/5 to 5
At 1/3 or 2/3 to 4/5, even if the output fluctuation changes from α1 to α2, the change is smaller than at other places. Therefore, if the threshold value of the comparison circuit is set to 1/5 to 1/3 or 2/3 to 4/5 of the normal output width,
The error is reduced, and a stable duty ratio of 50:50 is obtained.

According to the invention described in claim 5, according to claim 1,
In addition to the effect of the invention according to any one of claims 4 to 4, when the magnetic path changing piece moves by rotation of the rotating member, a plurality of magnetic fields divided into two groups according to the movement. In each group, the resistors are arranged in accordance with a change in the magnetic flux of the magnet caused by the movement of the magnetic path changing piece.
In the opposite state, the first magnetic resistance increases.
And the second state in which the magnetic resistance decreases are alternately repeated.

The bridge circuit outputs a detection signal to a comparison circuit in accordance with a change in the magnetic resistance of each of the magnetic resistors. According to the invention described in claim 6, the ratio of the interval length between the magnetic path changing pieces to the length in the rotational movement direction of the magnetic path changing pieces is 6
By arranging the magnetic path changing pieces so that 0:40, the operation of the invention described in any one of claims 1 to 5 is realized.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment in which the present invention is embodied in a rotation position sensor provided on a steering shaft of an automobile will be described below with reference to FIGS.

FIG. 1 is an exploded perspective view of a main part of a rotation position sensor. A rotation position sensor 1 as a rotation detection sensor includes:
It comprises a rotating plate 2 as a rotating member made of an iron plate and a magnetic detecting member 3. The rotating plate 2 rotates around its axis O (see FIG. 2) as the rotation center of the steering shaft 4 rotates.

As shown in FIG. 2, three arc-shaped magnetic path changing pieces 6a, 6b and 6c around the axis O are rotated at the outermost periphery in the rotation plane of the rotary plate 2. It is extended from the plate 2. The magnetic path changing pieces 6a, 6b, 6c
The one end to the other end are formed so as to form an angle of 48 degrees with respect to the axis O.

The intervals (spaces 7a, 7b, 7c) between the magnetic path changing pieces 6a, 6b, 6c are formed so as to form an angle of 72 degrees with respect to the axis O. In other words, these magnetic path changing pieces 6a, 6b, 6c and the spaces 7a, 7b, 7c
Alternately exist. At this time, the magnetic path changing piece 6
a, 6b, and 6c in the rotational movement direction and the spaces 7a, 7
The ratio of the lengths b and 7c in the rotational movement direction is 40:60.

A cylindrical magnetic path forming projection 8 is formed at the center of the rotating plate 2 so as to extend from the rotating plate 2 in the same direction as the magnetic path changing pieces 6a to 6c. Therefore, as shown in FIG. 3, when the rotary plate 2 is cut from the magnetic path changing pieces 6 a, 6 b, 6 c toward the axis O, the cross-sectional shape is
a, 6b, 6c, the rotating plate 2 and the magnetic path forming projection 8 form a U-shape.

A through hole 9 is formed in the magnetic path forming projection 8, and the steering shaft 4 is fixedly inserted therethrough. The magnetic detecting member 3 includes a main body 10 and a support arm 11. The detection unit main body 10 is located inside the magnetic path changing pieces 6a, 6b, 6c formed on the rotating plate 2 and between the magnetic path changing pieces 6a, 6b, 6c and the magnetic path forming protrusions 8. It is arranged in the space.

The detection unit main body 10 has three first to third magnetic detectors 13, 14, 15 sealed with a resin mold material 12 and fixed to the tip of the support arm 11. . The base end of the support arm 11 is fixed to a fixing member (not shown).

The first magnetic sensing element 13 includes a first magnetoresistive element 13a as a magnetic sensing element and a first bias magnet 13b as a magnet. The first bias magnet 13b is disposed so that the axial center O side is an S pole and the outside is an N pole,
2 and offset in the clockwise direction in FIG.

The first magnetic resistance element 13a is composed of a plurality of magnetic detection elements whose detection voltage changes depending on the direction of the magnetic flux of the first bias magnet 13b, that is, the resistance value of the first magnetic resistance element 13a depends on the direction of the magnetic flux as shown in FIG. Resistances R1, R2, R3, R4
It has. FIG. 5 is an explanatory diagram showing the arrangement of the resistors R1 to R4. As shown in the figure, two resistors R1 and R4
Are arranged in the same direction, and the resistors R2 and R3 are arranged in a direction orthogonal to the direction of the resistors R1 and R4. In FIG. 5, m and n indicate respective central axes indicating the directions in which the resistors R1 and R4 and the resistors R2 and R3 are directed.
R4 is formed by forming a NiCo thin film on the substrate in a polygonal line shape, and is set so that the resistance value is the same under the same temperature atmosphere. 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.

In this embodiment, the resistors R1 to R
4 and the center of change of the magnetic flux (in FIG. 5, A
(Indicated by a line). The angle center line of the resistors R1 to R4 is a bisector of an angle formed by mn passing through the base point at a point where the m and n lines intersect.

The range of the direction of the magnetic flux in this embodiment is such that the direction of the magnetic flux is substantially +
This is a range from the time when the direction becomes 45 ° to the time when the direction becomes substantially −45 ° with respect to the substantially radial direction.

FIG. 5 is an explanatory view when the resistors R1 to R4 are viewed from the rotating surface side of the rotating plate 2 in the direction in which the magnetic path changing piece 6a protrudes, and FIG. 2 and FIG. 5, the positional relationship between the resistors R1 and R4 and the resistors R2 and R3 is opposite in FIG.

When the direction of the magnetic flux is substantially + 45 ° from the axis O with respect to the substantially radial direction, the resistor R
1 and R4, and the resistance of the resistor R2
The resistance value of R3 increases. When the direction of the magnetic flux is substantially -45 degrees with respect to the substantially radial direction, the resistor R
1 and R4 increase, and the resistor R2
The resistance value of R3 decreases. In FIG. 5, the angle is defined as + in the clockwise direction.

The resistors R1 to R4 are connected to form a four-terminal bridge circuit B as shown in FIG.
The resistor R0 for threshold value adjustment is connected to the resistor R3 side.

A connection point (middle point) a between the resistor R1 and the resistor R2 is connected to an inverting input terminal of a comparator CP serving as a comparison circuit provided on the substrate, and is connected to the resistor R3 and the resistor R4. The connection point (middle point) b is the comparator C
It is connected to the non-inverting input terminal of P. The resistor R1
The circuit composed of the resistor R2 forms an output circuit. Further, the resistor R0 for threshold value adjustment has a smaller resistance value than the resistor R4, and unlike the resistors R1 to R4, is formed on the substrate with a material having a small temperature resistance change.

The detection circuit 20 is constituted by the comparator CP and the four-terminal bridge circuit (including the resistors R1 to R4 and the resistor R0) B. The resistors R1, R
Reference numeral 4 denotes a bridge circuit according to the present invention.

The resistors R1 and R4 of the detection circuit 20 are
The direction of the magnetic flux is approximately -45 from the axis O with respect to the substantially radial direction.
In the case of the orientation of °, the potential of the middle point a becomes the H level higher than the threshold voltage A1 described later (see FIG. 6). In FIG. 6, A0 indicates a potential level that is の of the saturation output at the middle point a. H is the threshold voltage A1, A0.
L indicates a lower level than the threshold voltages A1 and A0.

When the direction of the magnetic flux is substantially + 45 ° with respect to the above-mentioned substantially radial direction, the potential at the middle point a is at the L level from the threshold voltage A1 (see FIG. 6). The voltage at the middle point b on the reference voltage side of the comparator CP is set as follows. That is, in the case of normal temperature, the change in the voltage at the middle point a (waveform indicated by α1) due to the magnetic path changing pieces 6a, 6b, and 6c during the movement (rotation) as shown in FIG. At about 1/4 of W, the threshold value adjusting resistor R0 is adjusted so that when the duty ratio becomes 50:50, the threshold value (threshold) is based on the potential at the middle point b. Note that a threshold (threshold voltage) A
1 indicates that the voltage applied to the four-terminal bridge circuit B is V
cc, Vcc * (R4 + R0) / (R3 + R
4 + R0).

The detection point in this embodiment is the edge of the magnetic path changing pieces 6a, 6b, 6c in the rotating direction during the movement (rotation). Further, the potential of the middle point b is higher than the potential of the middle point b in the four-terminal bridge circuit including the resistors R1 to R4 when the threshold adjustment resistor R0 is omitted by the threshold adjustment resistor R0. As shown in 6,
That is, the threshold voltage (reference voltage) is changed from A0 level to A1 level.
It is going down to the level.

The threshold voltage (reference voltage) A1
Is set to a level of 1/4 of the normal output change width, and the duty ratio at the threshold voltage A1 is set to 50:50 in the case of a normal change.

The second magnetic detector 14 includes a second magnetic resistance element 14a as a magnetic detection element and a second bias magnet 14b as a magnet. The positional relationship between the second magnetoresistive element 14a and the second bias magnet 14b is the same as the positional relationship between the first magnetoresistive element 13a and the first bias magnet 13b. Then, the second magnetoresistive element 14a and the second bias magnet 14b are respectively different from the first magnetoresistive element 13a and the first bias magnet 13b in FIG.
It is disposed at a position of 40 degrees clockwise about the axis O.

The second magnetoresistive element 14a includes four resistors R as the magnetoresistors of the first magnetoresistive element 13a.
1, R2, R3, and R4 have the same configuration and four resistors electrically connected in the same manner. These resistors therefore include the four resistors R of the first magnetoresistive element 13a.
The same reference numerals are assigned to 1 to R4, and the description is omitted.

The resistor R1 of the second magnetoresistive element 14a
R4 together with the resistor R0 provided in the same manner as the resistor R0 provided in the first magnetoresistive element 13a constitute a four-terminal bridge circuit similar to that of the first magnetoresistive element 13a. Furthermore, the resistor R1 of the second magnetoresistive element 14a
R4 constitute a detection circuit 20 together with the resistor R0 and the comparator CP. The functions of the detection circuit 20 and the four-terminal bridge circuit B are the same as those of the detection circuit 20 in the case of the first magnetoresistive element 13a.

The third magnetic sensing element 15 includes a third magnetic resistance element 15a as a magnetic sensing element and a third bias magnet 15b as a magnet. The positional relationship between the third magnetoresistive element 15a and the third bias magnet 15b is the same as the positional relationship between the first magnetoresistive element 13a and the first bias magnet 13b. The third magnetoresistive element 15a and the third bias magnet 15b are different from the first magnetoresistive element 13a and the first bias magnet 13b in FIG.
It is disposed at a position of 40 degrees counterclockwise about the axis O.

The third magnetoresistive element 15a includes four resistors R as the magnetoresistors of the first magnetoresistive element 13a.
1, R2, R3, and R4 have the same configuration and four resistors electrically connected in the same manner. These resistors therefore include the four resistors R of the first magnetoresistive element 13a.
The same reference numerals are assigned to 1 to R4, and the description is omitted.

The resistor R1 of the third magnetoresistive element 15a
R4 together with the resistor R0 provided in the same manner as the resistor R0 provided in the first magnetoresistive element 13a constitute a four-terminal bridge circuit similar to that of the first magnetoresistive element 13a. Further, the resistor R1 of the third magnetoresistive element 15a
R4 constitute a detection circuit 20 together with the resistor R0 and the comparator CP. The functions of the detection circuit 20 and the four-terminal bridge circuit B are the same as those of the detection circuit 20 in the case of the first magnetoresistive element 13a.

The first to third bias magnets 1
3b to 15b and the first to third bias magnets 13b to 15b in the relative positional relationship between the magnetic path changing pieces 6a to 6c.
b is the third bias magnet 15b shown in FIG.
, That is, on the radiation passing from the axis O to the N pole (hereinafter referred to as “outside”), the magnetic path changing pieces 6a to 6c
In the case where there is any of the above, those magnetic fluxes are oriented at approximately -45 ° with respect to the approximately radial direction. This is the magnetic path changing piece 6
a to 6c, a rotating plate 2 and a magnetic path forming convex portion 8, a U-shaped magnetic path is formed, and the first to third bias magnets 1 are formed.
This is because magnetic flux is drawn from the N poles 3b to 15b to the magnetic path changing pieces 6a to 6c. As a result, the direction of the magnetic flux is
The magnetic path changing pieces 6a to 6c side, that is, approximately -4
5 ° orientation. That is, the magnetic path changing pieces 6a to 6c are magnetic path forming pieces.

Therefore, in this case, the voltage at the middle point a of the four-terminal bridge circuit B becomes H level. Also, the first to third
Bias magnets 13b to 15b and magnetic path changing pieces 6a to
6c, when each of the first to third bias magnets 13b to 15b is located at the position of the second bias magnet 14b shown in FIG.
If any of the magnetic path changing pieces 6a to 6c is not on the outer side of the pole, those magnetic fluxes are oriented at approximately + 45 ° with respect to the substantially radial direction. This is because the magnetic path changing pieces 6a to 6
Because there is no 6c, there is no magnetic flux. As a result, the magnetic flux extends radially, and the direction of the magnetic flux is substantially + 45 ° with respect to the substantially radial direction.

Therefore, in this case, the voltage at the middle point a of the four-terminal bridge circuit B outputs an L level voltage. Furthermore, in the relative positional relationship between the first to third bias magnets 13b to 15b and the magnetic path changing pieces 6a to 6c,
Each of the third bias magnets 13b to 15b corresponds to FIG.
And when passing from one end of the magnetic path changing pieces 6a to 6c from a position where the magnetic path changing pieces 6a to 6c do not exist,
The directions of the magnetic fluxes change from a direction of approximately + 45 ° with respect to the substantially radial direction to a direction of approximately −45 ° with respect to the substantially radial direction.

Therefore, in this case, the voltage at the middle point a of the four-terminal bridge circuit B outputs a voltage rising from the L level to the H level. Further, when the magnetic path changing pieces 6a to 6c pass through the end from a certain position, the directions of the magnetic fluxes are changed from a direction of approximately −45 ° to a substantially radial direction to a direction of approximately + 45 ° to a substantially radial direction. change.

Therefore, in this case, the voltage at the middle point a of the four-terminal bridge circuit B outputs a voltage that falls from the H level to the L level. In this manner, the potential of the middle point a of the four-terminal bridge circuit B becomes H level and L level, and the comparator CP of the detection circuit 20 rises and rises based on the middle point b which becomes the reference voltage (threshold voltage). The waveform is shaped into a detection signal having a sharp fall.

In the above description, in the normal case, the output waveform at the middle point a is the waveform indicated by α1 in FIG.
In FIG. 6, α1 in the L1 section is the first to third bias magnets 13b to 15b and the magnetic path changing pieces 6a to 6b.
In relation to the relative positional relationship with c, the waveform is when each of the first to third bias magnets 13b to 15b is located at the position of the third bias magnet 15b shown in FIG. In the relative position relationship between the first to third bias magnets 13b to 15b and the magnetic path changing pieces 6a to 6c, α2 in the L2 section indicates that each of the first to third bias magnets 13b to 15b The waveform is when it is located at the position of the second bias magnet 14b shown. Further, since the ratio of the length of the magnetic path changing pieces 6a, 6b, 6c in the rotational movement direction to the length of the spaces 7a, 7b, 7c in the rotational movement direction is 40:60, L1: L2 = 40:
It is 60.

On the other hand, when there is a large output fluctuation and the output waveform at the middle point a becomes α2 shown in FIG. 6, the detection point at the threshold voltage A1 changes from a1 to a2. In this case, assuming that the four-terminal bridge circuit is composed of the same resistors R1 to R4 as the conventional one, and the threshold voltage is A0, the detection point is b1 as shown in FIG.
To b2. If the difference between the detection points a1 and a2 in the present embodiment is d1, and the difference between the detection points b1 and b2 in the conventional case is d2, then d2> d1. this is,
Even when an output fluctuation occurs, the difference d1 is relatively small in the vicinity of 1/4 of the output change width W near the rising edge of the output waveform, whereas the difference d1 is relatively small. This is because the difference d2 becomes large at 1/2.

Therefore, in the present embodiment, even when the output fluctuates, the obtained duty ratio is approximately 5%.
0:50 and still stable. FIG. 7 shows a case where the output fluctuation is small. In this embodiment, since the threshold voltage is A1, it can be seen that the same duty ratio as that before the output fluctuation is obtained.

Next, the features of the rotational position sensor 1 configured as described above will be described below. (1) In the present embodiment, on the rotating surface of the rotating plate 2,
The ratio of the length of the magnetic path changing pieces 6a, 6b, 6c in the rotational movement direction to the length of the spaces 7a, 7b, 7c in the rotational movement direction is 40:
The magnetic path changing pieces 6a, 6b, 6
c. First to third bias magnets 13b arranged in a predetermined direction with respect to the rotating plate 2.
To 15b (magnet) and first to third bias magnets 1
Magneto-resistive elements 13a to 15a for detecting 3b to 15b
(Magnetic sensing element). And the magnetoresistive element 1
Magnetic path changing pieces 6a to 6c are formed by a predetermined arrangement of a plurality of resistors R1 to R4 (magnetic resistors) constituting 3a to 15a and a predetermined electrical connection between the resistors R1 to R4.
A circuit (output circuit) composed of a resistor R1 and a resistor R2 for obtaining a waveform output upon detection of the rotational movement of. Then, the output circuit converts the output signal into a normal output change width W.
And a comparator CP (comparing circuit) for shaping the waveform based on the threshold voltage A1 set so that the duty ratio is 50:50.

As a result, 出力 of the output change width W during normal operation is obtained.
In this case, even if the output variation changes from α1 to α2 as shown in FIG. 6, the variation is smaller than in other places. Therefore, the threshold voltage A1 of the comparator CP is set to the normal output variation width W. Is set to about 1/4, the error is reduced and a stable duty ratio of 50:50 can be obtained.

Further, since the duty ratio is set to 50:50, it is possible to easily perform the signal processing at the subsequent stage of the signal output from the comparator CP. (2) In the present embodiment, the plurality of magnetic resistors R1 to R4
Are caused by the movement of the magnetic path changing pieces 6a to 6c.
A first state in which the magnetic resistance is increased and a second state in which the magnetic resistance is decreased are alternately arranged in accordance with a change in magnetic flux of the third bias magnets 13b to 15b.
It was divided into two groups, and both groups were arranged so as to be in opposite states when there was a change in magnetic flux.

The circuit (output circuit) composed of the resistors R1 and R2 is a half bridge circuit composed of the resistors R1 and R2 belonging to both groups. As a result, when the magnetic path changing pieces 6a to 6c move due to the rotation of the rotating plate 2, the plurality of resistors R1 and R2 divided into two groups correspond to the movements.
According to the magnetic fluxes of the first to third bias magnets 13b to 15b generated by the movement of c, the respective groups are in a state opposite to each other, and a first state in which the magnetic resistance is increased, and a magnetic resistance is reduced. The second state can be alternately repeated.

Further, a circuit (half bridge circuit) composed of the resistor R1 and the resistor R2 can output a detection signal to the comparator CP according to a change in the magnetic resistance of each of the resistors R1 and R2.

(3) In the present embodiment, since the magnetic path changing pieces 6a to 6c for reducing external noise are formed integrally with the rotating plate 2, the number of parts does not increase and the number of assembling steps also increases. Never.

(4) In the present embodiment, the detection unit main body 1
Since 0 is disposed in the space located between the magnetic path changing pieces 6a to 6c and the magnetic path forming projection 8, the rotation position sensor does not increase in size.

(5) In the present embodiment, the magnetic path changing piece 6
a, 6b, and 6c in the rotational movement direction and the spaces 7a, 7
It is possible to obtain a waveform α1 corresponding to a ratio of 40:60 to the length of b, 7c in the rotational movement direction.

(Second Embodiment) A second embodiment in which the present invention is embodied in a rotational position sensor provided on a steering shaft of an automobile will be described below with reference to FIGS. 1, 2, and 8 to 1.
3 will be described. The same members as those in the first embodiment are denoted by the same reference numerals, and only different points will be described.

In the arrangement of the resistors R1 to R4 of the present embodiment, as shown in FIG.
The positional relationship between the resistors R1, R4 and the resistors R2, R3 is opposite to each other.

Therefore, when the direction of the magnetic flux is substantially + 45 ° from the axis O with respect to the substantially radial direction, the resistor R
1 and R4 increase, and the resistor R2
The resistance value of R3 decreases. When the direction of the magnetic flux is substantially -45 degrees with respect to the substantially radial direction, the resistor R
1 and R4, and the resistance of the resistor R2
The resistance value of R3 increases. Note that, in FIG. 9, the angle is + in the clockwise direction.

Further, as shown in FIG.
When the direction of the magnetic flux of the resistors R1 and R4 is substantially -45 degrees from the axis O with respect to the substantially radial direction, the potential of the middle point a becomes the L level larger than A0. When the direction of the magnetic flux is substantially + 45 ° with respect to the above-described substantially radial direction, the potential at the middle point a is at an H level higher than A0.

Further, as shown in FIG.
The voltage at the middle point b, which is on the reference voltage side of P, is a threshold (threshold) based on the potential of the middle point b when the duty ratio becomes 50:50 in about ／ of the output change width W.
Is adjusted by the threshold value adjusting resistor R0 so that

Each of the resistors R1 to R4 is connected to form a four-terminal bridge circuit B as shown in FIG.
The resistor R0 for threshold value adjustment is connected to the resistor R4.

Further, the potential at the middle point b is made higher than the potential at the middle point b in the four-terminal bridge circuit composed of the resistors R1 to R4 when the threshold adjustment resistor R0 is omitted by the threshold adjustment resistor R0. 10, as shown in FIG. 10, that is, the threshold voltage (reference voltage) is increased from the A0 level to the A1 level.

Then, the first to third bias magnets 1
3b to 15b and the first to third bias magnets 13b to 15b in the relative positional relationship between the magnetic path changing pieces 6a to 6c.
b is the third bias magnet 15b shown in FIG.
, The magnetic fluxes are oriented at approximately −45 ° with respect to the substantially radial direction.

Therefore, in this case, the voltage at the middle point a of the four-terminal bridge circuit B becomes L level. Also, the first to third
Bias magnets 13b to 15b and magnetic path changing pieces 6a to
6c, when each of the first to third bias magnets 13b to 15b is located at the position of the second bias magnet 14b shown in FIG. 2, their magnetic flux is substantially + 45 ° with respect to the substantially radial direction. Orientation.

Accordingly, in this case, the voltage at the middle point a of the four-terminal bridge circuit B outputs an H level voltage. Furthermore, in the relative positional relationship between the first to third bias magnets 13b to 15b and the magnetic path changing pieces 6a to 6c,
Each of the third bias magnets 13b to 15b corresponds to FIG.
And when passing from one end of the magnetic path changing pieces 6a to 6c from a position where the magnetic path changing pieces 6a to 6c do not exist,
The directions of the magnetic fluxes change from a direction of approximately + 45 ° with respect to the substantially radial direction to a direction of approximately −45 ° with respect to the substantially radial direction.

Accordingly, in this case, the voltage at the middle point a of the four-terminal bridge circuit B outputs a voltage that falls from the H level to the L level. Further, when the magnetic path changing pieces 6a to 6c pass through the end from a certain position, the directions of the magnetic fluxes are changed from a direction of approximately −45 ° to a substantially radial direction to a direction of approximately + 45 ° to a substantially radial direction. change.

Therefore, in this case, the voltage at the middle point a of the four-terminal bridge circuit B outputs a voltage which rises from the L level to the H level. As shown in FIG. 10, the output waveform α1 at the middle point a during normal time fluctuates greatly, and the output waveform α
When the number becomes 2, the detection point at the threshold voltage A1 changes from a1 to a2.

As shown in FIG. 10, the detection point is b1
To b2. If the difference between the detection points a1 and a2 in the present embodiment is d1, and the difference between the detection points b1 and b2 in the conventional case is d2, then d2> d1. this is,
Even when an output fluctuation occurs, the difference d1 is relatively small in the vicinity of 出力 of the output change width W near the fall of the output waveform, whereas the output change width W is relatively small. This is because the difference d2 becomes large at 1/2 of.

Therefore, in the present embodiment, the duty ratio obtained even when the output fluctuates is approximately 5
0:50 and still stable. FIG. 11 shows a case where the output fluctuation is small. In this embodiment, since the threshold voltage is A1, it can be seen that the same duty ratio as that before the output fluctuation is obtained.

Next, the features of the rotational position sensor 1 configured as described above will be described below. (6) In the present embodiment, the positional relationship between the resistors R1 and R4 and the resistors R2 and R3 is opposite to that of the first embodiment. Then, the output circuit forms the waveform of the output signal based on the threshold voltage A1 which is about ／ of the normal output change width W and the duty ratio is set to be 50:50. (Comparison circuit).

As a result, 3/4 of the output change width W during normal operation is obtained.
In this case, even if the output fluctuation changes from α1 to α2 as shown in FIG. 10, the change is smaller than in other places, so that the threshold voltage A1 of the comparator CP is set to the normal output change width W. About 3/4 of
Errors are reduced, and a stable duty ratio of 50:50 can be obtained.

Further, since the duty ratio is set to 50:50, it is possible to easily perform the signal processing at the subsequent stage of the signal output from the comparator CP. (7) In the present embodiment, the same effects as (2) to (5) can be obtained.

The embodiments are not limited to the above embodiments, but may be modified as follows. (A) In the first embodiment, the ratio of the length of the magnetic path changing pieces 6a, 6b, 6c in the rotational movement direction to the length of the spaces 7a, 7b, 7c in the rotational movement direction on the rotating surface of the rotating plate 2 is determined. The magnetic path changing pieces 6a, 6
b and 6c are erected, and the output signal from the middle point a is set to 1 of the normal output change width W so that the duty ratio becomes 50:50.
It was about / 4. However, the magnetic path changing pieces 6a, 6b,
The ratio of the length in the rotational movement direction of the space 6c to the length in the rotational movement direction of the spaces 7a, 7b, 7c is not limited to 40:60, but may be in the range of 35 to 45:65 to 55, and the duty ratio at that time The output signal from the middle point a may be within the range of 1/5 to 1/3 of the normal output change width W so that the ratio becomes 50:50.

In this case, the same effects as in the above (1) to (4) can be obtained. Also, the magnetic path changing pieces 6a, 6b, 6c
The waveform α1 corresponding to the ratio 35 to 45:65 to 55 of the length of the space 7a, 7b, 7c in the direction of rotation in the direction of rotation can be obtained.

(B) In the second embodiment, the rotating plate 2
On the rotating plate 2 such that the ratio of the length of the magnetic path changing pieces 6a, 6b, 6c in the rotational movement direction to the length of the spaces 7a, 7b, 7c in the rotational movement direction is 40:60 on the rotating surface of The changing pieces 6a, 6b, 6c are erected, and the duty ratio is 50: 5.
The output signal from the middle point a is set to about ／ of the output change width W in the normal state so as to be 0. However, the lengths of the magnetic path changing pieces 6a, 6b, 6c in the rotational movement direction and the spaces 7a, 7
The ratio of the lengths of the b and 7c in the rotational movement direction is not limited to 40:60, but may be in the range of 35 to 45:65 to 55, so that the duty ratio is 50:50.
The output signal from the middle point a is 2/3 of the normal output change width W.
It may be within the range of ４/4/5.

In this case, the above (2) to (4),
The same effect as (6) is achieved. Also, the magnetic path changing pieces 6a, 6
b, 6c in the direction of rotation and space 7a, 7b, 7c
The waveform α1 corresponding to the ratio 35 to 45:65 to 55 with respect to the length in the rotational movement direction can be obtained.

[0085]

As described above in detail, according to the first aspect of the present invention, the interval length between the magnetic path changing pieces and the length of the magnetic path changing pieces in the rotational movement direction are different from each other. I have. Therefore, the output circuit can obtain an output having a waveform corresponding to the ratio of the interval length of the magnetic path changing piece to the length of the magnetic path changing piece in the rotational movement direction.

According to the invention described in claim 2, according to claim 1
In addition to the effects described in the above, the ratio between the interval length of each magnetic path changing piece and the length of the magnetic path changing piece in the rotational movement direction is 65 to 55:35.
The magnetic path changing pieces are arranged so as to be 45. Therefore, the output circuit can obtain an output having a waveform corresponding to a ratio of 65 to 55:35 to 45.

According to the invention described in claim 3, according to claim 1
Alternatively, in addition to the effect of the invention described in claim 2, the output circuit is connected to a comparison circuit that shapes a waveform based on a threshold set to have a duty ratio of 50:50. Therefore, a signal having a duty ratio of 50:50 is input to the comparison circuit.

According to the invention set forth in claim 4, according to claim 1,
In addition to the effects of the invention according to any one of claims 3 to 3, the ratio of the interval length of the magnetic path changing piece to the length of the magnetic path changing piece in the rotational movement direction is 65 to 55:35 to 45. Each magnetic path changing piece is arranged so that Therefore, the threshold value of the comparison circuit is set to 1/5 to 1/3 or 2/3 to 2/3 of the normal output width.
At 4/5, a stable duty ratio of 50:50 with a small error can be obtained even when there is a large output fluctuation.

According to the invention set forth in claim 5, according to claim 1,
In addition to the effects of the invention described in any one of the fourth to fourth aspects, a large output change can be obtained at a detection point even with a small change in magnetic flux, and the output can be stably maintained even when the temperature or other state changes. Angle detection can be performed.

According to the invention set forth in claim 6, according to claim 1,
In addition to the effect of the invention according to any one of claims 5 to 5, the ratio of the interval length of the magnetic path changing piece to the length of the magnetic path changing piece in the moving rotation direction is 60:40. Each magnetic path changing piece is arranged. Therefore, the threshold value of the comparison circuit is set to 1/5 to 1/3 or 2/3 to 4/5 of the normal output change width.
In this case, a stable duty ratio of 50:50 with a small error can be obtained even when there is a large output fluctuation.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a main part of a rotation position sensor according to a first embodiment.

FIG. 2 is a plan view showing an arrangement relationship between a rotating plate and a magnetoresistive element.

FIG. 3 is a sectional view of a main part of the rotation position sensor.

FIG. 4 is an equivalent circuit of a magnetoresistive element.

FIG. 5 is an explanatory diagram showing an arrangement relationship of resistors.

FIG. 6 is an output waveform diagram of a voltage at the middle point.

FIG. 7 is an output waveform diagram at the middle point when the output fluctuation is small.

FIG. 8 is an equivalent circuit of a magnetoresistive element according to the second embodiment.

FIG. 9 is an explanatory diagram showing an arrangement relationship of resistors.

FIG. 10 is an output waveform diagram of a voltage at the middle point.

FIG. 11 is an output waveform diagram at the middle point when the output fluctuation is small.

[Explanation of symbols]

1 ... Rotation position sensor as rotation detection sensor, 2 ... Rotating plate as rotation member, 6a, 6b, 6c ... magnetic path changing piece
13a: a first magnetoresistive element as a magnetic sensing element, 13
b: a first bias magnet as a magnet; 14a: a second magnetoresistive element as a magnetic sensing element; 14b: a second bias magnet as a magnet; 15a: a third magnetoresistive element as a magnetic sensing element; The third
Bias magnets, R1 to R4: resistors as magnetic resistors.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masahiro Taniguchi 3-260 Toyota, Oguchi-machi, Niwa-gun, Aichi Prefecture Inside Tokai Rika Electric Works, Ltd. 2F063 AA35 CA40 DA05 DD04 EA03 GA52 GA68 GA69 KA02 KA04 2F077 AA45 CC02 NN04 NN23 PP14 QQ02 VV02

Claims (6)

[Claims] 1. A rotating member having a plurality of magnetic path changing pieces disposed at predetermined intervals in a rotational movement direction, a magnet disposed in a predetermined direction with respect to the rotating member, and a plurality of detecting magnets. A magnetic sensor element, and a predetermined arrangement of a plurality of magnetic resistors constituting each of the magnetic sensor elements, and a predetermined electrical connection between the respective magnetic resistors, the magnetic path changing piece has In a rotation detection sensor that constitutes an output circuit that obtains a waveform output upon detection of rotation movement, a ratio of an interval length of each of the magnetic path changing pieces and a length of the magnetic path changing piece in a rotational movement direction is different. Rotation detection sensor. 2. A ratio of an interval length of each magnetic path changing piece to a length of the magnetic path changing piece in a rotational movement direction is 65 to 55:35.
The rotation detection sensor according to claim 1, wherein the magnetic path change pieces are arranged so as to be −45. 3. The output circuit has a duty ratio of 50: 5.
3. The rotation detection sensor according to claim 1, wherein the rotation detection sensor is connected to a comparison circuit that shapes a waveform based on a threshold value set to be zero. 4. An output circuit according to claim 1, wherein said output signal is set to have a duty ratio of 50:50, which is 1/5 to 1/3 or 2/3 to 4/5 of a normal output change width. The rotation detection sensor according to claim 1, wherein the rotation detection sensor is connected to a comparison circuit that shapes a waveform based on a set threshold value. 5. The plurality of magnetic resistors (R1 to R4)
Are arranged so as to alternately repeat a first state in which the magnetic resistance increases and a second state in which the magnetic resistance decreases according to a change in magnetic flux of the magnet caused by movement of the magnetic path changing piece. And the two groups are arranged so as to be in opposite states when the magnetic flux changes, and the output circuit includes a plurality of magnetic resistors (R1 to R4) respectively belonging to the two groups. 5) is a bridge circuit electrically connected, the rotation detection sensor according to any one of claims 1 to 4. 6. The magnetic path changing piece is arranged such that a ratio of an interval length of each magnetic path changing piece to a length in a rotational movement direction of the magnetic path changing piece is 60:40. 6. The rotation detection sensor according to any one of items 5.