JP5266986B2 - Sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor capable of detecting both a position and velocity. <P>SOLUTION: The sensor includes: a magnet member containing a first magnet which is in a shape expanding in a prescribed direction and has magnetic poles opposite in polarity at its both ends, and a second magnet which has magnet poles arranged in its expanding direction in such a pattern that polarities are repeatedly reversed in an area distant from both ends on the lateral side; a coil into which the magnet member is inserted; a magnetic sensor which is disposed inside the coil so as to face the second magnet; and a holding mechanism for holding at least one of the coil and the magnet member so that the magnet member can be moved relative to the coil in the expanding direction. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

The present invention also relates to the sensor.

  For example, a position sensor and a speed sensor are used for feedback control in a keyboard instrument including a force sense control device that gives a desired touch feeling to a player's key operation (see, for example, Patent Document 1). . For example, in the keyboard instrument disclosed in Patent Document 1, a position sensor and a speed sensor are prepared separately.

  As a position sensor, for example, there is a combination of a gray scale and a photoelectric sensor, and the position of the gray scale (a member connected to) is detected from a change in the output voltage of the photoelectric sensor. Further, as a speed sensor, for example, there is a combination of a permanent magnet and a coil, and the speed of the permanent magnet (a member connected thereto) is detected from the induced electromotive force generated in the coil. Although it is possible to calculate the speed from the time derivative of the detected position using only the position sensor, such a method detects the sequential average speed, and it is difficult to obtain accurate speed information.

JP 2005-195619 A

One object of the present invention, the position can be detected, it is to provide a sensor that can detect more speed example.

According to the first aspect of the present invention, a first magnet having a shape extending in a predetermined direction and having magnetic poles of opposite polarities arranged at both ends, and a polarity in a region away from the both ends on the side surface A magnet member including a second magnet in which magnetic poles are arranged in the extending direction in a pattern that is repeatedly reversed, a detection coil in which the magnet member has entered, and the second magnet in the detection coil holding a magnetic sensor arranged opposite, so that relatively said magnet member with respect to the detection coil is movable with respect to the extending direction, at least one of the detection coil and the magnet member and A sensor having a retention mechanism is provided.

In the sensor according to the first aspect, the magnet member including the first magnet and the second magnet is movable relative to the detection coil in which the magnetic sensor is disposed. For example, it is possible to detect the relative velocity of the magnet member or the detection coil by induced electromotive force generated in the detection coil in response to the relative speed of the first magnet relative to the detection coil changes. Further, the output of the magnetic sensor changes according to the relative position of the second magnet, it is possible to detect the relative position of the magnet member or the detection coil.

  First, a position / velocity detection apparatus according to an embodiment of the present invention will be described.

  FIG. 1A and FIG. 1B are a longitudinal sectional view and a lateral sectional view, respectively, of a position / velocity detecting device of an embodiment. For example, an electric wire is wound around a bobbin (tubular body) 1 made of a heat-resistant resin (for example, about 1000 turns) to form a speed detection coil 2.

  A rod-shaped magnet member 3 that is long in the length direction of the bobbin 1 is disposed so as to be movable in the length direction of the bobbin 1. The magnet member 3 includes a speed detecting magnet 3a and a position detecting magnet 3b.

  The speed detection magnet 3a is a bar magnet that is fully magnetized in the length direction and has N poles and S poles arranged at both ends. For example, the speed detection magnet 3a is formed of ferrite and has a substantially cylindrical shape with a diameter of 4 mm and a length of 30 mm. It is. A part of the cylinder is cut off so that a surface parallel to the center line of the cylinder is exposed, and a groove 3c extending in the length direction of the cylinder is formed on this surface.

  The groove 3c is filled with a plastic magnet (plamag) material, and the filled plamag material is magnetized in a pattern in which N poles and S poles are alternately arranged in the length direction of the speed detection magnet 3a. A position detecting magnet 3b is formed. The width of the position detection magnet 3b (the width of the groove 3c) is, for example, 1.5 mm. The magnetized portion 3d of the position detection magnet 3b is, for example, a portion having a length of about 20 mm at the center of the magnet member 3, and is disposed away from both end portions where the magnetic poles of the speed detection magnet 3a are disposed. The distance (magnetization pitch) between the N pole and S pole adjacent to the position detection magnet 3b is, for example, 600 μm.

  A position detection magnetic sensor 4 is disposed on the inner surface of the bobbin 1 facing the position detection magnet 3b. As the position detection magnetic sensor 4, for example, a full bridge type magnetoresistive sensor is used. The dimension of the position detecting magnetic sensor 4 is, for example, about 1 mm to 2 mm. The position detecting magnetic sensor 4 is attached to the bobbin 1 via a magnetic shield member 5.

  FIG. 1C is a schematic perspective view showing the bobbin 1, the magnetic shield member 5 attached thereto, and the position detection magnetic sensor 4. In the magnetic shield member 5, the position detecting magnetic sensor 4 is held on the inner surface by an adhesive, for example, and the outer surface is a shield portion 5a constituting the top surface 5S, and the length direction of the bobbin 1 from the shield portion 5a. Are formed to include shield portions 5b and 5c extending back and forth. The dimension in the length direction of the magnetic shield member 5 is, for example, about 5 mm to 6 mm. The shield parts 5b and 5c are inclined so as to enter the inside of the bobbin 1 as they move away from the shield part 5a, and are arranged on the inner side of the top surface 5S of the shield part 5a. Positioning portions A1 and A2 projecting on both sides from the top surface 5S of the shield portion 5a are provided.

  As the magnetic shield member 5, a high magnetic permeability material having a high saturation magnetic flux density, such as electromagnetic soft iron, 45% permalloy, or the like is used. The magnetic shield member 5 is preferably formed so as not to have a pin angle.

  The bobbin 1 is provided with a through hole h for fitting the magnetic shield member 5 and recesses B1 and B2 into which the positioning portions A1 and A2 are fitted. The magnetic shield member 5 to which the magnetic sensor 4 is attached is pushed into the through hole h so that the positioning portions A1 and A2 are in contact with the recesses B1 and B2, respectively, and the magnetic shield member 5 is fixed to the bobbin 1 with an adhesive, for example. . The magnetic shield member 5 is arranged so that the top surface 5S is slightly recessed from the outer surface of the bobbin 1.

  After attaching the magnetic shield member 5, as shown in FIG. 1A and FIG. 1B, a wire is wound around the outer surface of the bobbin 1 to form the speed detection coil 2. Since the top surface 5S is recessed from the outer surface of the bobbin 1, contact between the magnetic shield member 5 and the speed detection coil 2 can be avoided. The speed detection coil 2 is fixed with resin.

  Next, the speed detection operation will be described. As the magnet member 3 moves in the length direction inside the bobbin 1 around which the speed detection coil 2 is wound, the magnetic flux generated from the magnetic pole of the speed detection magnet 3a and passing through the speed detection coil 2 is temporally changed. As a result, an induced electromotive force is generated in the speed detection coil 2. Since the induced electromotive force is proportional to the speed of the speed detecting magnet 3a, that is, the speed of the magnet member 3, the speed detecting device that detects the speed of the magnet member 3 by measuring the induced electromotive force generated in the speed detecting coil 2. Can be configured. Note that when the direction of movement of the magnet member 3 is reversed, the polarity of the induced electromotive force is reversed.

  FIG. 2A is a graph schematically showing a time change of the induced electromotive force generated in the speed detection coil 2. The horizontal axis indicates time t, and the vertical axis indicates the induced electromotive force V. This example shows a change in electromotive force when the magnet member 3 is moved at a constant speed in the speed detection coil 2. However, immediately after the start of movement and immediately before the end of movement, the induced electromotive force V linearly increases and decreases with respect to the time t, and the constant-speed movement in which the induced electromotive force V is constant. I am doing.

  Note that, by narrowing the magnetization pitch of the position detection magnet 3b to about 600 μm, for example, most of the magnetic flux generated by the magnetic poles of the position detection magnet 3b stays near the surface of the position detection magnet 3b, and the speed detection coil 2 is suppressed, the influence on the speed detection due to the magnetic flux of the position detecting magnet 3b is reduced.

  Next, the position detection operation will be described. When the magnet member 3 moves in the length direction, the magnetization pattern of the position detection magnet 3b moves immediately below the position detection magnetic sensor 4, and the output signal of the position detection magnetic sensor 4 changes.

  FIG. 2B is a graph schematically showing changes in the output signal of the position detecting magnetic sensor 4 as the magnet member 3 moves for one stroke. The horizontal axis indicates the position of the magnet member 3, and the vertical axis indicates the output of the magnetic sensor 4. Because the polarity of the magnetic pole arranged immediately below the position detection magnetic sensor 4 is reversed at every magnetization pitch of the position detection magnet 3b, the polarity of the output signal of the position detection magnetic sensor 4 is also reversed, and the output signal is Change periodically. For example, it is possible to configure a position detection device that detects the amount of movement of the magnet member 3 from the reference position by counting the number of cycles of the output signal. Furthermore, more accurate position detection can be performed by detecting the phase in the cycle.

However, the closer to both ends of the magnet member 3, the larger the magnetic flux of the speed detecting magnet 3a applied as an external magnetic flux, and the apparent detection sensitivity of the position detecting magnetic sensor 4 decreases. That means
The amplitude of the output signal is maximized at the central portion farthest from both ends of the magnet member 3, and decreases as the distance from the central portion increases. In order to perform position detection, the output signal is desired to have a waveform with uniform amplitude with respect to the position of the magnet member 3 in the length direction.

  In this embodiment, in order to reduce the influence of the speed detection magnet 3a in position detection, the magnetized portions of the position detection magnet 3b are arranged away from both ends of the speed detection magnet 3a. Furthermore, the outside of the position detection magnetic sensor 4 is covered with a magnetic shield member 5 (so as not to cover the surface facing the position detection magnet 3b). As a result, the magnetic flux generated by the magnetic pole of the speed detection magnet 3a bypasses the outside through the magnetic shield member 5, and is difficult to enter between the magnetic sensor 4 and the position detection magnet 3b. The influence on the position detection caused by the magnetic flux 3a is reduced.

  However, even if these measures are taken, the influence of the magnetic flux of the speed detection magnet 3a increases as the distance from the both ends of the magnet member 3 increases. Therefore, it is possible to completely prevent the signal output of the position detection magnetic sensor 4 from decreasing. Is difficult.

  Therefore, as shown in FIG. 2C, after removing a region where the noise is close to the edge as necessary, a region where a sufficiently large signal output is obtained, the gain adjustment is performed according to the position, and the amplitude is obtained. A waveform having a uniform number is generated as a position detection signal. For example, the position detection signal in which the variation due to the position of the amplitude is reduced can be generated by the correction in which the coefficient is set to the minimum 1 at the center portion of the magnet member 3 and the coefficient is increased as the distance from the center portion increases. The correction coefficient can be obtained by experiment, for example. A table storing coefficients for each position can be stored in a memory and used at the time of position detection signal generation processing. For such processing, for example, a signal processing means 10 using a computer is prepared. Further, for example, the amplitude can be made uniform by changing the reference voltage of the comparator according to the position.

  As described above, the position / velocity detection apparatus of the present embodiment can simultaneously detect both the position and the speed with a single detection apparatus. For example, this detection device can be used as an operator of a musical instrument such as a synthesizer. For example, position information can be used as control information, and the vibrato depth of a musical sound can be changed by real-time control when a musical sound is generated (after a key is pressed). Can be used as control information for vibrato speed. At the next key press, the last last vibrato depth and speed data is taken over, and the change can be made by operating the operator again. For example, it can be used for a solenoid for an automatic performance piano, a motor (linear), and other mechanisms that reciprocate linearly.

  In addition, the thing of the various structure used for the well-known magnetic scale can be used as the magnetization pattern of the position detection magnet 3b, and the position detection magnetic sensor 4. FIG. The magnetization direction of the magnetized portion of the position detecting magnet 3b can be the vertical direction (thickness direction) or the horizontal direction (in-plane direction).

  In addition, as the magnet member 3, the following structural examples are also considered. For example, the magnet member 3 can be formed of a single ferrite member in which speed detection magnetic poles are arranged at both ends and position detection magnetic pole patterns are arranged on the side surfaces.

  Further, for example, a rod-like support member made of stainless steel or the like is formed with a groove extending in the length direction, filled with a plamag material in the groove, and the filled plamag member is magnetized in the length direction to be It is also possible to form the magnet member 3 by disposing a speed detecting magnetic pole on the side and further disposing a position detecting magnetic pole pattern on the side surface of the plastic magnet member.

  In addition, although the case where the magnet member 3 moves with respect to the speed detection coil 2 and the position detection magnetic sensor 4, that is, the case where the position and speed on the magnet member 3 side are detected has been described. It can be used to detect the position and speed on the speed detection coil 2 and position detection magnetic sensor 4 side by moving the detection coil 2 and position detection magnetic sensor 4. If the speed detection coil 2 and the position detection magnetic sensor 4 and the magnet member 3 move relatively, they function as a position speed detection device.

  FIG. 3A is a diagram showing a case where the speed detection coil 2 and the position detection magnetic sensor 4 are fixed and the magnet member 3 moves, and FIG. 3B is a diagram where the magnet member 3 is fixed and the speed detection coil 2 and FIG. 3C is a diagram showing a case where the magnet member 3, the speed detection coil 2 and the position detection magnetic sensor 4 are movable, respectively. .

  The magnet member including the speed detection magnet and the position detection magnet is not limited to a straight bar shape. For example, it may be possible to use a U shape or a substantially ring shape with a ring cut, although the sensitivity will be low. However, the magnet member is magnetized in the extending direction, speed detection magnetic poles are arranged at both ends, and the position detection is arranged on the side surface of the magnet member in a pattern in which the polarity is repeatedly reversed. A number of magnetic poles are arranged. The speed detecting coil in which the magnet member moves (relatively) defines a cylindrical region along the length of the magnet member.

  In addition, the combination of the speed detection coil 2 and the speed detection magnet 3a can be used as an electromagnetic actuator. In such a case, the apparatus includes a position detection device and an electromagnetic actuator. In the case of an electromagnetic actuator, a stopper mechanism that limits the movable region can be provided as necessary.

  Next, a keyboard instrument having a performance operator actuator unit to which the position / velocity detecting device of the embodiment is applied will be described.

  4A and 4B show a configuration example of the actuator unit, FIG. 4A is a schematic sectional view in the length direction of the actuator unit, and FIG. 4B is a schematic plan view seen from the direction of arrow A in FIG. 4A.

  FIG. 4B shows an actuator assembly in which a plurality of actuator units 12a, 12b. Each actuator unit 12a, 12b,... Is provided corresponding to each key of a keyboard instrument such as a piano, for example, and is used to give an arbitrary touch feeling (reaction force) to the player's key operation.

  In FIG. 4A, the structure of one actuator unit 12a is shown in detail by a cross-sectional view in the vertical axis direction. The actuator units 12a, 12b,... Are configured in the same manner. In the following description, only the components of the actuator 12a are denoted by symbols, and the others are represented.

  The actuator unit 12a is roughly composed of an actuator unit 20 made of an electromagnetic solenoid and a position / speed sensor unit 30 for detecting the operation position and operation speed of the mover of the actuator unit 20. As the position / velocity sensor unit 30, the position / velocity detection apparatus of the above embodiment can be applied.

  The actuator unit 20 is covered with a yoke 11, and each actuator unit 12 a, 12 b... Is disposed in the yoke 11, so that a plurality of actuator units 12 a, 12 b. The yoke 11 is held in common. The actuator unit 12a (12b...) Has a casing member 13 fixed with screws on the bottom surface of the yoke 11.

  The actuator unit 20 includes an electromagnetic solenoid coil 21 disposed in the yoke 11 and a rod-shaped plunger (movable element) 22 inserted in the axial center of the coil 21 so as to be capable of bidirectional linear movement. The coil 21 is disposed with its axis oriented in the vertical direction, and upper and lower ends thereof are connected to through holes provided in the upper surface and the bottom surface of the yoke 11, thereby allowing the plunger 22 to pass through the through hole. From the upper end of the plunger 22, a shaft 23 extends coaxially with the plunger 22, and a shaft head 24 to be brought into contact with a corresponding key is provided at the tip of the shaft 23.

  The plunger 22 is always urged upward by a spring 25 disposed in the casing member 13, and the spring 25 is attached even when a normal actuator is not driven (the electromagnetic coil 21 is energized off). The force is held at the top dead center position as shown in FIG. 4A. The spring 25 is used to support the plunger 22 so that it does not fall by its own weight, and the biasing force has only a strength necessary to support the weight of the plunger 22 and a strong force that does not apply an extra load beyond that. It is preferable.

  In the illustrated example, the actuator unit 12a is configured as an actuator for touch application, and thus includes a spring 25 that supports the plunger 22 from below. The operation of the actuator unit 12a during touch addition control will be described later. Depending on the application of the actuator (for example, when the actuator is used as a key driving actuator), the spring 25 may not be provided.

  At the lower end of the plunger 22, a rod-shaped magnet member 31, which is a constituent element of the position / speed sensor unit 30, extends coaxially with the plunger 22. The bottom surface of the casing member 13 is provided with a hole 31a that allows the magnet member 31 to pass therethrough, and the magnet member 31 passes therethrough. That is, the magnet member 31 as one component of the position / velocity sensor unit 30 is unitized by being coaxially connected to the plunger 22 and moves integrally with the linear movement of the plunger 22.

  The bobbin 32 is installed on the lower surface of the lower casing member 13 with its length direction along the linear movement direction of the plunger 22, and its upper end opening is connected to the hole portion 31 a to allow the magnet member 31 to enter. Yes. When the plunger 22 is linearly displaced, the magnet member 31 intrudes / retreats relative to the bobbin 32 integrally with the displacement.

  A position detection magnetic sensor 33 is disposed on the inner surface of the bobbin 32, and a speed detection coil 34 is wound on the outer surface of the bobbin 32. As described above, the magnet member 31 includes the position detection magnet and the speed detection magnet, and the position detection magnetic sensor 33 faces the magnetic pattern of the position detection magnet. The position and speed of the magnet member 31 are detected from the output signals of the position detection magnetic sensor 33 and the speed detection coil 34, respectively. Since the magnet member 31 moves integrally with the plunger 22 and the shaft head 24, the position and speed of the plunger 22 and the shaft head 24 can be obtained.

  As shown in FIG. 4B, the actuator units 12a, 12b... Are arranged with their relative positions adjacent to each other being different in a two-row dispersive manner (staggered). Since each component of the actuator units 12a, 12b,... Can be realized with a small and simple configuration, the above arrangement example is possible. The staggered arrangement allows the adjacent actuator units 12a, 12b,... To be sufficiently spaced apart from each other, so that even if the solenoid coils of the units 12a, 12b,. Operational irregularities due to are prevented.

  FIG. 4C is a diagram schematically showing an arrangement relationship between keys and actuator units in the keyboard musical instrument of this application example. One of a plurality of keys is shown as a representative. The same applies to other keys. The key 40 has a seesaw-type structure that rotates around a rotation shaft 41. The actuator unit 12a is arranged so that the shaft head 24 comes into contact with the position on the lower surface side of the corresponding key 40 and in front of the rotation shaft 41 (player side). The keyboard instrument in this example is not provided with an action mechanism as in an acoustic piano, and an appropriate pressing / releasing key reaction force can be obtained exclusively by an actuator unit.

  The operation of touching the corresponding key with the actuator unit 12a will be described. As shown in FIG. 4A, the actuator unit 12a is in a state where the plunger 22 has entered the coil 21 from the normal time (when not driven). At this time, the tip of the shaft head 24 is in contact with the corresponding key (at the rest position), and when the performer presses the key, the plunger 22 can be displaced downward in conjunction with this.

  When a drive signal (current) is supplied from the driver 100 to the actuator unit 20 and the coil 21 is energized, a force that attracts the plunger 22 is generated in the coil 21. A force to retain is applied. As a result, a reaction force is applied to the depressed key, and a touch feeling of the key operation is given to the operator. By varying the drive signal supplied to the actuator unit 20, the force for attracting the plunger 22 can be appropriately controlled, and an arbitrary touch can be added to the key pressing operation. For example, even a keyboard with a mechanism without an action member or a hammer such as an acoustic piano can be played with a touch as if they exist.

  In order to realize the touch addition control by the actuator accurately and with high accuracy, the quality of the feedback signal (detection signal) obtained by sensing the movement of the plunger 22 is an extremely important factor. In the actuator unit 12a to which the position / velocity detection device of the embodiment is applied, the position information and speed information of the plunger 22 can be measured at the same time, and these two actually measured values can be used as feedback signals. Thereby, highly accurate feedback control can be realized and the performance of touch addition control can be improved.

Note that the force F for driving the actuator for touch addition is given by the following equation of motion (see “Best Mode for Carrying Out the Invention” in Japanese Patent Laid-Open No. 2005-195619).
F = MX ″ + ΡX ′ + KX (Formula 1)
In (Expression 1), X is position information, X ′ is speed information, X ″ is acceleration information, M is mass, Ρ is a viscosity coefficient, and K is a spring coefficient. In the actuator unit of this application example, the position speed sensor The position information X and the speed information X ′ are actually measured in the unit 30. The acceleration information X ″ can be calculated using the actually measured speed information X ′.

  For example, in a performance operator actuator unit as disclosed in “Example 1” of Japanese Patent Application Laid-Open No. 2005-195619, a position detection device for position detection and a speed detection device for speed detection are separately provided. Although necessary, in the actuator unit of this application example, the position and the speed can be detected simultaneously by one detection device.

  In addition, although the application example which gives a desired touch feeling with respect to a player's key operation was demonstrated, the position speed detection apparatus of an Example can also be applied to an automatic performance piano. In an automatic performance piano, an unattended key pressing operation is performed by pushing up a key with a plunger of an actuator unit arranged on the lower side of each key. In an automatic performance piano, the position information and speed information of the plunger are used to accurately feedback control the force for driving the key. The position / velocity detecting device of the embodiment can also be incorporated in the key driving actuator unit of the automatic performance piano.

  In addition, for example, an actuator unit incorporating the position / velocity detection device of the embodiment may be arranged for a pedal of a keyboard instrument such as an electronic piano in order to give a feeling similar to that of a damper pedal of an acoustic piano, for example. it can.

  In addition to keys and pedals, actuators such as pitch bend wheels used for musical instruments, and actuators that give operational feeling and automatic operation to other operators used for game machines etc. The position / velocity detecting device of the embodiment can be incorporated.

  The position / velocity detection apparatus of the embodiment can be widely applied to a control mechanism that uses both position information and speed information as control information. For example, it can be applied to vehicle suspension control to contribute to stable running, it can be applied to printer operation control to perform high-speed and quiet printing operations, and good control of agitation equipment used for cooking, dispensing, etc. Can contribute.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

1A and 1B are a schematic longitudinal sectional view and a lateral schematic sectional view of a position / velocity detecting device according to an embodiment, respectively. FIG. 1C is a schematic perspective view showing a bobbin, a magnetic shield member, and a magnetic sensor. is there. FIG. 2A is a graph schematically showing an induced electromotive force generated in the speed detection coil, and FIG. 2B is a graph schematically showing an output signal of the position detection magnetic sensor accompanying the movement of the magnet member. FIG. 2C is a diagram showing a flow of processing of an output signal of the position detection magnetic sensor. FIG. 3A to FIG. 3C are diagrams showing movement modes of the magnet member, the speed detection coil, and the position detection magnetic sensor. 4A and 4B are a schematic longitudinal sectional view and a schematic plan view, respectively, of an actuator unit of an application example, and FIG. 4C is a diagram schematically showing an arrangement example of a key and an actuator unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bobbin 2 Speed detection coil 3 Magnet member 3a Speed detection magnet 3b Position detection magnet 4 Position detection magnetic sensor 5 Magnetic shield member

Claims (4)

A first magnet having a shape extending in a predetermined direction and having magnetic poles of opposite polarities arranged at both ends, and a magnetic pole extending in a pattern in which the polarity is repeatedly reversed in a region on the side surface away from the both ends A magnet member including a second magnet arranged in a line;
A coil for detection in which the magnet member enters,
A magnetic sensor disposed inside the detection coil so as to face the second magnet;
Sensor including a holding mechanism that holds at least one of the so relatively said magnet member with respect to the detection coil is movable with respect to the extending direction, the detection coil and the magnet member. The sensor according to claim 1, further comprising a magnetic shield member disposed on the detection coil side of the magnetic sensor.   The signal processing means for processing an output signal from the magnetic sensor output in accordance with the position in the extending direction of the magnet member so that the amplitude approaches uniformly with respect to the position in the extending direction. Or the sensor of 2.   The sensor according to claim 1, wherein the magnetic sensor is a magnetoresistive element.

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