JP2012078124A - Electromagnetic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress influence of induced electromotive force which is generated by a magnetic field of a magnet affecting a substrate.SOLUTION: An electromagnetic device includes a substrate 3, and a magnet 2 which is positioned opposite to the substrate 3 and has an S pole and an N pole in the surface opposite to the substrate 3. The substrate 3 has an electric component 4, and a plurality of pieces of electric wiring 5a, 5b which are connected to the electric component 4 and drawn on the substrate 3. The magnet 2 and the substrate 3 are movable or rotatable relatively to each other. The plurality of pieces of electric wiring 5a, 5b include: a part 5X which is located in the drawing direction seen from the electric component 4 and in which the induced electromotive force is generated by magnetic force produced by the magnet 2 when the magnet 2 and the substrate 3 move or rotate relatively to each other; and a part 5Y which is located on the side opposite to the drawing direction seen from the electric component 4 and where induced electromotive force with polarity opposite to the polarity of the induced electromotive force is generated.

Description

  The present invention relates to electromagnetic devices.

  There is a sensor device as an example of an electromagnetic device that includes a substrate and a magnet that is disposed to face the substrate and has a south pole and a north pole in a plane that faces the substrate. For example, the sensor devices described in Patent Documents 1 and 2 have a sensor having a circuit including a magnetoresistive element as a detection circuit on a substrate. According to this sensor device, the change in the electric resistance of each magnetoresistive element caused by an external magnetic field is obtained, and based on the change, the direction of the magnetic field applied from the magnet to the sensor is obtained. Therefore, if a sensor including the above-described circuit is provided on a substrate fixed to a position opposite to the magnet to be measured, the position and rotation angle of the measured member can be measured. is there. It is also conceivable to attach a sensor to the member to be measured and fix the magnet at a position facing it.

  In an electromagnetic device including such a sensor, if a current that causes noise is generated in the circuit and the electrical wiring connected thereto, the detection accuracy is greatly reduced. In particular, when a circuit is provided facing the magnet and the magnet and the circuit move or rotate relative to each other, generation of induced electromotive force becomes a problem. For example, FIG. 8 shows the output voltages of the two circuits (almost 0V) when no induced electromotive force is generated in a state where the number of rotations of the magnet is sufficiently reduced and the electrical wiring connected to the circuit is short-circuited away from the magnet. )It is shown. On the other hand, FIG. 9 shows the output voltage of the electrical wiring connected to the two circuits when the magnet rotates at 3000 rpm. According to this, it can be seen that a voltage of about −0.004 V to 0.004 V is generated in the electric wiring due to the induced electromotive force. Further, FIG. 10 shows the result of obtaining the difference between the maximum value and the minimum value of the voltage under each condition by changing the rotation speed of the magnet. According to this, it can be seen that the induced electromotive force increases as the rotational speed of the magnet increases, and cannot be ignored.

  Patent Documents 3 to 6 are not related to a sensor including a circuit as described above. However, in view of the generation of induced electromotive force, in an audio signal intermittent relay, a semiconductor device, a magnetic head, and a current detector. A method to reduce the generation of induced electromotive force is proposed.

  Further, Patent Document 7 discloses a configuration using a twisted pair wire as the electrical wiring in order to cancel out noise generated from the electrical wiring connecting the electrical component and the control unit.

JP 2009-281784 A JP 2007-309694 A Japanese Utility Model Publication No. 60-134260 JP 58-66575 A JP-A-6-243436 JP 58-221172 A JP 2002-187504 A

  Patent Documents 3 to 6 suggest that the generation of dielectric electromotive force is reduced, but it is not considered to cancel the induced electromotive force. That is, it is not considered to cancel and invalidate the induced electromotive force after confirming the generation of the induced electromotive force, and therefore the electric wiring is not arranged in a special form. Therefore, as a matter of course, the relevance of the portion for canceling the induced electromotive force with the magnet for applying the magnetic field that is a factor for generating the induced electromotive force is not taken into consideration. The relative positional relationship and specific shape of the part with respect to the magnet are not defined. In addition, Patent Document 7 does not have a configuration in which a magnet is disposed opposite to an electrical component and an electrical wiring, so that a magnetic field is applied to the electrical wiring and the magnet and the electrical wiring move or rotate relatively. The generation of induced electromotive force is not considered at all.

  Accordingly, an object of the present invention is to provide an electromagnetic device capable of suppressing the influence of an induced electromotive force generated by a magnetic field exerted by a magnet on a substrate disposed facing the magnet.

  The electromagnetic device of the present invention includes a substrate, and a magnet that is disposed opposite to the substrate and has a south pole and a north pole in a plane facing the substrate. The substrate includes an electrical component and an electrical component, respectively. A plurality of electrical wirings connected to each other and drawn on the substrate are formed. The magnet and the substrate can move or rotate relative to each other, and when the magnet and the substrate move or rotate relative to each other, a dielectric electromotive force is generated by the magnetic force received from the magnet. And a portion where an induced electromotive force having a polarity opposite to that of the induced electromotive force is generated.

  At least one pair of electrical wirings are connected to each other through electrical components, and are drawn out in the same pulling direction as viewed from the electrical components, and one electrical wiring is electrically connected on the side in the pulling direction as viewed from the electrical components. Connected to the component and pulled out in the pull-out direction, and the other electric wiring is connected to the electric component on the opposite side to the pull-out direction when viewed from the electric component, and the range facing the magnet on the opposite side to the pull-out direction After being extended to the outside, it is bent and pulled out in the pulling direction, and the portion of the electric wiring that is located in the pulling direction when viewed from the electric component is the portion where the dielectric electromotive force is generated. The part located on the opposite side to the pulling direction when viewed from the electrical component may be a part where an induced electromotive force having the opposite polarity is generated.

  In that case, the area of the substrate surrounding the pair of electrical wirings on the side in the drawing direction as viewed from the electrical component, and the area surrounding the pair of electrical wirings on the side opposite to the drawing direction as viewed from the electrical component. It is preferable that they match. Here, on the substrate, within a range facing the magnet, the area surrounded by the pair of electric wirings on the side in the drawing direction as viewed from the electric component, and the pair on the side opposite to the drawing direction from the electric component. It is good also as a structure with which the area which an electrical wiring encloses corresponds.

  Further, at least one pair of electrical wirings are connected to each other through electrical components, extend along the pull-out direction, intersect each other at a position facing the magnet edge, and outside the range facing the magnet. It is formed so as to extend along the pull-out direction, and the portion located inside the range facing the magnet of the electric wiring is the portion where the dielectric electromotive force is generated, and is larger than the range facing the magnet of the electric wiring. The configuration may be such that the portion located outside is a portion where an induced electromotive force having the opposite polarity is generated.

  According to the present invention, the electrical wiring connected to the electrical component is provided with a portion where an induced electromotive force is generated and a portion where an induced electromotive force having the opposite polarity is generated. When an induced electromotive force is generated in a part, an induced electromotive force having an opposite polarity that cancels the induced electromotive force is also generated. Therefore, the induced electromotive force and the induced electromotive force having the opposite polarity cancel each other, and noise with respect to the input / output of the electrical component is suppressed, so that the electromagnetic device can function accurately with desired performance.

It is a perspective view which shows an example of the magnet and board | substrate of the electromagnetic device of this invention. It is a top view which shows the board | substrate of the electromagnetic device shown in FIG. It is a top view which shows the other example of the board | substrate of the electromagnetic device of this invention. It is a graph which shows the magnetic field strength applied to each part of a substrate with a magnet. (A) is a partial cross-sectional side view schematically showing an example of the magnet and substrate of the electromagnetic device of the present invention, and (b) is a part of schematically showing another example of the magnet and substrate of the electromagnetic device of the present invention. It is a cross-sectional side view. It is a circuit diagram which shows an example of the detection circuit and processing apparatus of the electromagnetic device of this invention. It is the schematic of the principal part which shows the state which incorporated the sensor device which is an example of the electromagnetic device of this invention in the vehicle. It is a graph which shows the output voltage of the electromagnetic device of the state which fully reduced the rotation speed of the magnet in the conventional electromagnetic device. It is a graph which shows the output voltage of the electromagnetic device of the state which rotated the magnet in the conventional electromagnetic device. It is a graph which shows the relationship between the rotation speed of the magnet in the conventional electromagnetic device, and the difference of the maximum value and minimum value of output voltage.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Basic configuration of sensor as an example of electromagnetic device]
As an example of the electromagnetic device of the present invention, there is a sensor device that detects the angle of a member to be detected. As shown in FIGS. 1 and 2, the sensor device includes a magnet (permanent magnet) 2 attached to the member to be detected 1 and a substrate 3 fixed at a position facing the magnet 2. The magnet 2 has an S pole and an N pole in a plane facing the substrate 3. The substrate 3 is provided with a sensor 4 that is an example of an electrical component, and an electrical wiring 5 that is connected to the sensor 4. The sensor 4 is located at the center of the substrate 3 and substantially opposite to the center of the magnet 2, and has a built-in detection circuit 6 whose output changes according to a magnetic field applied from the outside. A specific configuration of the detection circuit 6 will be described later with reference to FIG. By measuring the output of the detection circuit 6, the direction of the magnetic field applied from the outside can be detected. As a result, the relative position and angle of the detected member 1 to which the magnet 2 is attached to the sensor 4 on the substrate 3. Can know.

  In such a sensor device, when the magnet 2 attached to the member to be detected 1 moves or rotates, an induced electromotive force is generated in the electric wiring 5 on the substrate 3. Specifically, the magnetic flux applied from the magnet 2 to the electrical wiring 5 changes as the magnet 2 moves or rotates, so that an induced current flows through the electrical wiring 5.

  In this sensor device, the output of the detection circuit 6 of the sensor 4 is originally transmitted to the processing device 9 (see FIG. 6) including the voltmeter 7 and the processing circuit 8 and analyzed, so that the magnet 2 is attached. The relative position and angle of the detected member 1 with respect to the substrate 3 can be obtained with high accuracy. However, conventionally, when the induced current generated in the electrical wiring 5 is added to the output of the detection circuit 6, the relative position and angle of the detected member 1 may not be accurately obtained. Therefore, in the present invention, in addition to the portion 5X in which the induced electromotive force of one polarity (for example, positive) is generated in the electrical wiring 5, the induced electromotive force of the opposite polarity (for example, negative) (inducing induced electromotive force) A portion 5Y is provided in which is generated. As a result, the induced electromotive force and the canceling induced electromotive force cancel each other, and only the output of the detection circuit 6 flows in the electric wiring 5 without noise. As a result, the relative position and angle of the detected member 1 can be obtained with high accuracy.

[First example of electrical wiring]
In the example shown in FIG. 2, a pair of electrical wires 5 a and 5 b connected to each other via the sensor 4 are drawn out in one direction A (for example, the downward direction in FIG. 2) on the substrate 3. One electrical wiring 5a is connected to the sensor 4 on the drawing direction (direction A) side and is drawn out in the drawing direction (direction A) as it is. However, the electrical wiring 5b is connected to the sensor 4 on the side opposite to the drawing direction (direction A) (upper side in FIG. 2), and from there to the direction B (upward direction in FIG. 2) opposite to the drawing direction (direction A). Once drawn around, it extends outside the range facing the magnet 2, that is, outside the position facing the edge E of the magnet 2 (shown by a broken line in FIG. 2), then bent and pulled out. It is pulled out in the direction (direction A).

  In such a configuration, when the magnet 2 moves or rotates relative to the substrate, the magnetic flux from the N pole to the S pole existing in the plane of the magnet 2 facing the substrate 3 (FIG. 5A, (See (b)) passes through the loop formed by the electric wires 5a and 5b. In this way, when the polarity of the magnet 2 applied to the loop formed by the electric wires 5a and 5b changes, an induced electromotive force is generated in the electric wires 5a and 5b. The induced electromotive force (cancellation induced electromotive force) generated in the portion 5Y on the opposite direction (direction B) side with respect to the induced electromotive force generated on the portion 5X on the pulling direction (direction A) side as viewed from the sensor 4 is The opposite polarity. Therefore, the two induced electromotive forces cancel each other. Since only the output of the detection circuit 6 flows through the electrical wires 5a and 5b, the relative position and angle of the detected member 1 can be obtained with high accuracy.

  In this way, an induced electromotive force is generated by the magnetic force received from the magnet 2 in the part 5X on the side of the drawing direction (direction A) when viewed from the sensor 4 of the pair of electric wires 5a and 5b. In the portion 5Y on the opposite side (direction B) as viewed, a canceling induced electromotive force having a polarity opposite to that of the induced electromotive force is generated by the magnetic force received from the magnet 2. If the induced electromotive force and the canceling induced electromotive force are opposite in polarity and substantially in size, they cancel each other and affect the output of the detection circuit 6 flowing in the electric wirings 5a and 5b. Absent.

  The area surrounded by the pair of electric wires 5a and 5b on the side of the drawing direction (direction A) as viewed from the sensor 4 and the pair of electric wires 5a and 5b on the side of the opposite direction (direction B) as viewed from the sensor 4 If the surrounding area substantially matches, it is easy to make the induced electromotive force and the canceling induced electromotive force have opposite polarities and the same size as described above. It is effective to cancel each other. Further, within the range facing the magnet 2, that is, within the range facing the edge E of the magnet 2 (shown by a broken line in FIG. 2), in the pulling direction (direction A) side as viewed from the sensor 4. The area surrounded by the pair of electric wirings 5a and 5b and the area surrounded by the pair of electric wirings 5a and 5b on the opposite direction (direction B) side as viewed from the sensor 4 may be substantially the same. Good. In order to easily realize such a configuration, as described above, the electrical wiring 5b is located outside the range facing the magnet 2 in the direction B opposite to the drawing direction (direction A), that is, the edge E of the magnet 2. It is routed to the outside of the position opposite to (shown by a broken line in FIG. 2).

  In the example shown in FIGS. 1 and 2, another pair of electric wirings 5 a ′ and 5 b ′ is provided. The electrical wirings 5a 'and 5b' have substantially the same configuration as the electrical wirings 5a and 5b, although the drawing direction is reversed. That is, the lead-out direction of the electric wirings 5a 'and 5b' is the direction B (upward direction in FIG. 2), and the opposite direction is the direction A (downward direction in FIG. 2). The electrical wirings 5a and 5b are connected to the processing device 9 as output lines of the detection circuit 6, and the electrical wirings 5a'5b 'are connected to the power supply 10 and the ground terminal 11, respectively. Also in the electric wires 5a ′ and 5b ′, the induced electromotive force generated in the portion 5X ′ on the drawing direction (direction B) side as viewed from the sensor 4 is the reverse generated in the portion 5Y ′ on the opposite direction (direction A) side. It is canceled by the induced electromotive force for canceling the polarity. As a result, only the output of the detection circuit 6 flows through the electrical wirings 5a 'and 5b', and the relative position and angle of the detected member 1 can be obtained with high accuracy. Note that the drawing direction of the electric wirings 5a 'and 5b' may coincide with the drawing direction of the electric wirings 5a and 5b.

  As will be described later, a part of the electric wirings 5a, 5b, 5a ′, 5b ′ is led to the back surface of the substrate 3 through the through holes 14 (see FIGS. 5A and 5B). There are also parts not shown in FIGS.

[Second example of electrical wiring]
FIG. 3 shows another example of the electric wiring on the substrate 4 of the present invention. In this example, a pair of electrical wirings 12 a and 12 b connected to each other via the sensor 4 are drawn out in one direction (for example, the downward direction A in FIG. 3) on the substrate 3. The electric wirings 12a and 12b extend along the pull-out direction (direction A), and then at the edge of the range facing the magnet 2, in other words, at the position facing the edge E of the magnet 2, 12b crosses. That is, the positions of the electric wirings 12a and 12b in the direction orthogonal to the drawing direction (direction A) are interchanged. Then, outside the range facing the magnet 2 (outside the position facing the edge E of the magnet 2), the processing device extends in the drawing direction (direction A) with the positional relationship changed as described above. 9 is connected. Here, the interchanged positional relationship does not necessarily mean that the distance between the electric wirings 12a and 12b is constant, and the distance between the electric wirings 12a and 12b before and after the intersection is changed to the left and right. However, the distance between the electric wirings 12a and 12b may be constant. At a point 12Z where the two electric wirings 12a and 12b intersect, an insulating material (not shown) is interposed between the two electric wirings 12a and 12b so as not to conduct (short-circuit) each other.

  With such a configuration, of the electrical wirings 12a and 12b, the portion 12X within the range facing the magnet 2 and the portion 12Y outside the range facing the magnet 2 are twisted at the intersection 12Z. Therefore, the induced currents flowing in both portions 12X and 12Y are reversed. That is, the induced electromotive forces generated in both portions 12X and 12Y have opposite polarities and cancel each other. Then, only the output of the detection circuit 6 flows through the electrical wirings 12a and 12b, and the relative position and angle of the detected member 1 can be obtained with high accuracy.

  As described above, in a portion of the pair of electric wirings 12a and 12b that faces the magnet 2 (portion where the induced electromotive force is generated) 12X, the induction induction is caused by the magnetic flux received from the magnet 2 as in the conventional case. While electric power is generated, an induced electromotive force having a reverse polarity (cancellation for canceling) is generated by a magnetic flux received from the magnet 2 in a portion 12Y outside the range facing the magnet 2 (portion where the canceling induced electromotive force is generated) 12Y. Induced electromotive force).

  In the example shown in FIG. 3, another pair of electric wirings 12 a ′ and 12 b ′ is provided. The electrical wirings 12a 'and 12b' have substantially the same configuration as the electrical wirings 12a and 12b, although the drawing direction is reversed. That is, the direction in which the electrical wirings 12a 'and 12b' are drawn out is the direction B (upward direction in FIG. 2). The electrical wirings 12a and 12b are connected to the processing device 9 as output lines of the detection circuit 6, and the electrical wirings 12a'12b 'are connected to the power supply 10 and the ground terminal 11, respectively. Note that the drawing direction of the electric wirings 12a 'and 12b' may coincide with the drawing direction of the electric wirings 12a and 12b.

  As will be described later, a part of the electric wirings 12a, 12b, 12a ′, 12b ′ is led to the back surface of the substrate 3 through the through holes 14 (see FIGS. 5A and 5B). There are also parts not shown in FIG.

  Here, the reason why the intersections 12Z and 12Z 'of the electrical wirings 12a, 12b, 12a', and 12b 'are provided at positions facing the edge E of the magnet 2 in the configuration shown in FIG.

  FIG. 4 shows the magnetic field intensity Bz in a direction perpendicular to the substrate 3 applied to the substrate 3 facing the magnet 2 having a diameter of 10 mm. As shown in FIG. 4, the maximum value and the minimum value of the magnetic field strength Bz are generated near the edge E of the magnet 2 (a position where the distance from the center of the magnet 2 (a point where x = 0 mm and y = 0 mm) is 5 mm). You can see that Therefore, as shown in FIG. 3, when the electric wirings 12a, 12b, 12a ′, 12b ′ are crossed (twisted) in the vicinity of the edge E of the magnet 2 where the maximum value and the minimum value of the magnetic field intensity are generated, When the intersections 12Z, 12Z ′ of the wirings 12a, 12b, 12a ′, 12b ′ are arranged in the vicinity of the edge E of the magnet 2, the time change of the magnetic field inside and outside the intersections 12Z, 12Z ′ becomes substantially constant, and the intersection 12Z. , 12Z ′, the induced electromotive force generated in the inner portions 12X, 12X ′ is well canceled by the canceling induced electromotive force generated in the outer portions 12Y, 12Y ′ of the intersections 12Z, 12Z ′. The effect is obtained.

  If the intersections 12Z, 12Z ′ of the electrical wirings 12a, 12b, 12a ′, 12b ′ are arranged on the inner side of the position facing the edge E of the magnet 2, the areas of the inner portions 12X, 12X ′ of the intersection 12Z are increased. The induced electromotive force generated in the portions 12X and 12X ′ is reduced. On the other hand, since the areas of the portions 12Y and 12Y ′ outside the intersections 12Z and 12Z ′ become large and the induced electromotive force for cancellation generated in the portions 12Y and 12Y ′ becomes too large, the balance between both induced electromotive forces is poor and the reverse Polarity induced current is added to the current flowing through the electrical wirings 12a, 12b, 12a ′, 12b ′.

  Also, if the intersections 12Z, 12Z ′ of the electrical wirings 12a, 12b, 12a ′, 12b ′ are arranged outside the position facing the edge E of the magnet 2, the portions 12X, 12X, The area of 12X ′ increases, and the induced electromotive force generated in the portions 12X and 12X ′ increases. On the other hand, the areas of the portions 12Y and 12Y 'outside the intersections 12Z and 12Z' are reduced, and the canceling induced electromotive force generated in the portions 12Y and 12Y 'is reduced, so that the induced electromotive force cannot be fully canceled.

  Therefore, as shown in FIG. 3, when the intersections 12Z, 12Z ′ of the electric wirings 12a, 12b, 12a ′, 12b ′ are arranged at positions facing the edge E of the magnet 2, portions inside the intersections 12Z, 12Z ′. The induced electromotive force generated at 12X and 12X ′ and the induced electromotive force for cancellation generated at the portions 12Y and 12Y ′ outside the intersections 12Z and 12Z ′ are offset in a balanced manner.

  2 and the example shown in FIG. 3 are combined, and some of the electrical wirings provided on the substrate 3 are pulled out as seen from the sensor 4 as shown in FIG. A plurality of pairs of electric wirings, including direction-side portions 5X, 5X ′ (portions where induced electromotive force is generated) and opposite-side portions 5Y, 5Y ′ (portions where induced electromotive force for cancellation is generated) As shown in FIG. 3, the other part includes intersections 12Z and 12Z ′, portions 12X and 12X ′ (portions where induced electromotive force is generated) inside intersections 12Z and 12Z ′, and intersection 12Z. , 12Z ′ may be configured to include portions 12Y and 12Y ′ (portions where the canceling induced electromotive force is generated).

[Disposition of electrical wiring in the thickness direction of the substrate]
Next, the arrangement of the electric wires 5 and 12 in the thickness direction of the substrate 3 will be described. As indicated by arrows in FIGS. 5A and 5B, the magnetic flux from the circular magnet 2 is directed in a direction perpendicular to the magnet 2 and the substrate 3 in the vicinity of the edge E of the magnet 2. In the central part, it faces in a direction parallel to the magnet 2 and the substrate 3. The induced electromotive force is generated by the flow of magnetic flux across the electric wirings 5 and 12. Therefore, in order to reduce the induced electromotive force, the magnetic flux from the magnet 2 is prevented from crossing the electric wirings 5 and 12 as much as possible. That is, it is preferable to arrange the electric wires 5 and 12 so as to be as parallel as possible to the magnetic flux from the magnet 2. Therefore, as shown in FIG. 5A, the electrical wirings 5 and 12 are formed in parallel on the substrate 3 at a position facing the center of the magnet 2, and through at a position facing the edge E of the magnet 2. It is preferable to arrange the electric wirings 5 and 12 perpendicularly to the thickness direction of the substrate using the holes 14.

  Further, when a magnetic flux in a direction perpendicular to the magnet 2 and the substrate 3 is generated near the center of the magnet 2 for some reason, a step is provided on the substrate as shown in FIG. Thus, it is preferable to direct the electric wirings 5 and 12 in the vertical direction at the portion where the magnetic flux in the vertical direction is generated.

  The arrangement of the electrical wirings 5 and 12 in the thickness direction of the substrate 3 as shown in FIGS. 5A and 5B is parallel to the arrangement in the surface direction of the substrate 3 shown in FIGS. And it can be done.

[Detailed configuration of detection circuit]
An example of the detection circuit 6 configured in the sensor (electrical component) 4 on the substrate 3 will be described in detail below. As schematically shown in FIG. 6, the detection circuit 6 includes a Wheatstone bridge 6a. In the circuit diagram shown in FIG. 6, the Wheatstone bridge 6a has four magnetoresistive elements (MR elements, for example, a tunnel magnetoresistive element (TMR element)) 13 arranged on four sides of a square. This square point P2 is connected to the power source 10, and a point P4 opposite to the point P2 is connected to the ground terminal 11. Further, the two points P1 and P3 are connected to the voltmeter 7 to detect a potential difference (hereinafter referred to as “output voltage”) between the points P1 and P3. Based on this output voltage, the processing circuit 8 detects a change in the resistance value of each MR element 13. Note that the description in the present specification regarding the arrangement of the MR elements 13 and the like relates to the layout on the circuit diagram shown in FIG. The actual mounting position of each MR element 13 or the like on the substrate 3 is not limited by these descriptions and FIG. 6 and can be arbitrarily changed. For example, the MR element 13 has a giant magnetoresistive effect. An element (GMR element) may be used.

  The MR element 13 has a resistance value that changes depending on the relative relationship between the fixed magnetization direction of the pinned layer and the magnetization direction of the free layer that changes according to the external magnetic field. In the Wheatstone bridge 6a of the detection circuit 6, the pinned layers of the MR elements 13 positioned on adjacent sides of the quadrangle in the circuit diagram shown in FIG. 6 have magnetization directions opposite to each other, as shown in FIG. In the circuit diagram, the pinned layers of the MR element 13 facing each other across the center of the quadrangle have the same magnetization direction. Examples of these magnetization directions are indicated by arrows in FIG.

  In such a configuration, for example, when the right external magnetic field 23 of FIG. 6 is applied to the detection circuit 6 as shown in the figure, the resistances of the four MR elements 13 of the Wheatstone bridge 6a are all equal. The output voltage becomes zero. Then, as the direction of the external magnetic field 23 changes from the direction indicated by the arrow (for example, counterclockwise), the output voltage of the Wheatstone bridge 6a changes. If the change of the output voltage with respect to the change of the angle of the external magnetic field 23 is represented by a graph, it is represented by a sinusoidal curve although not shown. Therefore, when the output voltage of the Wheatstone bridge 6a is measured, the direction (angle) of the external magnetic field 23 is known. Therefore, the position (rotation angle) of the magnet 2 (see FIG. 1) exerted on each MR element 13 of the detection circuit 6 can be obtained from the direction of the external magnetic field 23.

  And each electric wiring 5a, 5b, 5a ', 5b', 12a, 12b, 12a ', 12b' of this detection circuit 6 is part 5X, 5X which generate | occur | produces an induced electromotive force, as shown in FIG. '12X, 12X' and portions 5Y, 5Y ', 12Y, 12Y' for generating canceling induced electromotive forces, respectively. Therefore, even if the magnet facing the substrate on which the detection circuit 6 is provided moves or rotates relatively to generate an induced electromotive force, the positive induced electromotive force and the negative induced electromotive force cancel each other. . Thereby, an induced current is not added to the current supplied to the voltmeter 7, and the output voltage can be measured with high accuracy. In addition, a predetermined power supply can be maintained without being influenced by the induced electromotive force in the path connecting the power source 10 and the ground terminal 11.

[Applications of electromagnetic devices]
A typical example of the electromagnetic device of the present invention is an angle detection means having a sensor 4 incorporating the above-described detection circuit 6. In the example shown in FIG. 7, a magnet (permanent magnet) 2 is attached to a part of a shaft 1a of a vehicle handle (steering wheel) 1 which is a detected member. The substrate 3 is fixed to a mounting member (not shown) at a position facing the magnet 2. The detection circuit 6 on the substrate 3 is connected to the motor 25 via the processing device 9, and a pinion 25 a of the motor 25 is connected to a gear 26 a attached to the steering axle 26. The steering axle 26 is connected to the shaft 1 a of the handle 1. Therefore, when the driver turns the handle 1, the magnet 2 attached to the shaft 1a moves, and the output voltage of the Wheatstone bridge 6a of the detection circuit 6 changes from the magnet 2. When the voltmeter 7 detects the change in the output voltage of the Wheatstone bridge 6a and the processing circuit 8 calculates the position of the magnet 2, the rotation angle of the handle 1 is determined. Then, the motor 25 is operated according to the rotation angle, and the steering axle 26 is rotated via the pinion 25a and the gear 26a. The rotation of the steering axle 26 by the motor 25 acts as a steering assist when the user turns the steering wheel 1, and so-called power steering is realized in which steering can be performed with a small force.

  Of course, the electromagnetic device of the present invention is not limited to the angle sensor for the vehicle handle 1 shown in FIG. 7, but various detected members such as a brushless motor, a fan, a mirror of a laser printer, an indirect mechanism of a robot, and the like. It can be used as a sensor that detects the position and angle of the. Furthermore, the substrate 3 having the electrical component 4 and the electrical wiring connected to the electrical component 4 is disposed so as to face the magnet 2 in any application, not limited to the sensor, and the magnet 2 is relative to the substrate 3. The present invention is effective in any electromagnetic device as long as it is an electromagnetic device that moves or rotates in a moving manner and that does not preferably generate an induced electromotive force in the electrical wiring 5.

  Further, the magnet 2 is not limited to the circular permanent magnet as shown in FIG. 1 and may be any magnet as long as it exerts a magnetic field on the substrate 3 including an electromagnet or the like.

  When manufacturing the electromagnetic device of the present invention, the output of the electrical wirings 5 and 12 is measured while actually moving or rotating the magnet 2 relative to the substrate 3 so that the output is minimized. The dimensions and shapes of the portions 5Y, 5Y ′, 12Y, and 12Y ′ where the canceling induced electromotive force of the electric wirings 5 and 12 is generated may be determined by trial and error.

1 Detected member (handle, steering wheel)
1a shaft 2 magnet (permanent magnet)
3 Substrate 4 Electrical component (sensor)
5, 5a, 5b, 5a ′, 5b ′ Electrical wiring 5X, 5X ′ Pull-out side portion (portion where induced electromotive force is generated)
5Y, 5Y 'Opposite direction part (part where induced electromotive force of opposite polarity is generated)
6 Detection circuit (circuit)
6a Wheatstone bridge 7 Voltmeter 8 Processing circuit 9 Processing device 10 Power supply 11 Grounding terminals 12, 12a, 12b, 12a ′, 12b ′ Electric wiring 12X, 12X ′ Parts within the range facing the magnet (induced electromotive force is generated portion)
12Y, 12Y ′ A portion outside the range facing the magnet (a portion where an induced electromotive force having the opposite polarity is generated)
12Z, 12Z 'intersection 13 magnetoresistive element (MR element)
14 through-hole 23 external magnetic field 25 motor 25a pinion 26 steering axle 26a gear E edge of magnet

Claims (13)

A substrate, and a magnet disposed opposite to the substrate and having an S pole and an N pole in a plane facing the substrate,
The substrate is formed with an electrical component and a plurality of electrical wirings connected to the electrical component and drawn on the substrate,
The magnet and the substrate are movable or rotatable relative to each other;
The plurality of electrical wirings include a portion where a dielectric electromotive force is generated by a magnetic force received from the magnet when the magnet and the substrate move or rotate relative to each other, and a polarity opposite to the induced electromotive force. An electromagnetic device including a portion where an induced electromotive force is generated. At least one pair of the electrical wirings are connected to each other via the electrical component, and are drawn out in the same pulling direction as viewed from the electrical component;
One of the electrical wirings is connected to the electrical component on the side in the pulling direction as viewed from the electrical component, and is pulled out in the pulling direction,
The other electrical wiring is connected to the electrical component on the side opposite to the pulling direction when viewed from the electrical component, and is bent after extending to the outside opposite to the magnet on the side opposite to the pulling direction. Is pulled out in the pulling direction,
A portion of the electrical wiring located in the pull-out direction when viewed from the electrical component is a portion where the dielectric electromotive force is generated,
2. The electromagnetic device according to claim 1, wherein a portion of the electrical wiring that is located on the opposite side to the pulling direction when viewed from the electrical component is a portion where an induced electromotive force having the opposite polarity is generated.   An area on the substrate surrounding the pair of electrical wirings on the side in the drawing direction when viewed from the electrical component, and an area surrounding the pair of electrical wirings on the side opposite to the drawing direction when viewed from the electrical component. The electromagnetic device according to claim 2, wherein the area to be matched is the same.   Within the range facing the magnet, on the substrate, the area surrounded by the pair of electric wirings on the side in the pulling direction as viewed from the electric component, and the side opposite to the pulling direction from the electric component The electromagnetic device according to claim 3, wherein an area surrounded by the pair of electric wirings is the same. At least one pair of the electrical wirings are connected to each other via the electrical components, extend along the pull-out direction, intersect each other at a position facing the edge of the magnet, and from a range facing the magnet. Is also formed to extend along the pull-out direction on the outside,
The portion of the electrical wiring located inside the range facing the magnet is a portion where the dielectric electromotive force is generated,
2. The electromagnetic device according to claim 1, wherein a portion of the electric wiring located outside a range facing the magnet is a portion where an induced electromotive force having the opposite polarity is generated.   The electromagnetic device according to claim 1, wherein the magnet is rotatable in a plane parallel to the substrate, and the electric component is disposed at a position facing a rotation center of the magnet. .   The electromagnetic device according to claim 1, wherein the induced electromotive force is equal to the induced electromotive force having the opposite polarity.   Either one of the magnet and the substrate is fixed, the other is attached to a member to be measured, and the electrical component is a sensor that detects a position or a rotation angle of the member to be measured. The electromagnetic device according to any one of the above. The sensor includes a detection circuit including a magnetoresistive effect element,
A change in the relative position of the magnet and the sensor can be detected by detecting a change in the resistance value of the magnetoresistive element that accompanies a change in magnetic force exerted on the magnetoresistive element from the magnet. Item 9. The electromagnetic device according to Item 8.   The electromagnetic device according to claim 9, wherein the sensor includes a detection circuit including a Wheatstone bridge configured by connecting a plurality of magnetoresistive elements to each other.   The electromagnetic device according to claim 10, wherein the magnetoresistive effect element is a giant magnetoresistive effect element.   The electromagnetic device according to claim 10, wherein the magnetoresistive effect element is a tunnel magnetoresistive effect element.   The electromagnetic device according to any one of claims 9 to 12, which is a sensor device that detects a position or a rotation angle of the member to be measured.

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