JP2009300143A - Magnetic position detecting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic position detecting apparatus which is good for being made compact and low-power-consumption, and can precisely detect a position and a movement value of a moving object. <P>SOLUTION: A magnetoelectric device 104 is disposed near one end 112a of a magnetized area 112 of a magnetic drum 111, so as to be opposite and close to it in a noncontact fashion. Therefore, a change in a strength of a magnetic field being applied to the magnetoelectric device along with a rotation of the magnetic drum, is represented by a sine wave on which a DC bias magnetic field is superimposed. The influence of the hysteresis characteristic of a magnetic sensor on an output signal wave of the magnetic position detecting apparatus can be reduced by using the DC bias magnetic field. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magnetic position detection device that detects, for example, the amount and position of a rotary moving body.

  A conventional magnetic position detecting device includes a rotary moving body (magnetic drum) in which N and S poles are alternately magnetized at a magnetization pitch λ, and a magnetic sensor that detects the magnetic field strength of the rotary moving body. . As the magnetic sensor, a magnetoresistive element (MR element) in which the resistance value of the element changes due to a change in the magnetic field, or a Hall element in which the output voltage of the element changes due to the change in the magnetic field is used. Conventionally, an anisotropic magnetoresistive element (AMR element) is used as an MR element in a magnetic position detecting device. In the AMR element, the resistance value changes only when the direction of the flowing current is set to the easy axis direction of the AMR element and a magnetic field is applied in a direction orthogonal to the easy axis direction (hard axis direction). In such an AMR element, the resistance change characteristic (hereinafter referred to as “MR curve”) of the AMR element with respect to the magnetic field has a hysteresis characteristic in which the resistance change varies depending on the polarity of the magnetic field.

  In recent years, giant magnetoresistive elements (GMR elements) and tunneling magnetoresistive elements (TMR elements) that cause a larger resistance change with respect to a larger magnetic field than AMR elements have been developed. For example, in an exchange coupling type GMR element, the direction of current to flow is set to the easy axis of magnetization of the GMR element, the resistance value changes when a magnetic field is applied in the element plane, and the shape anisotropy is present. When the GMR element has, for example, a vertically long stripe shape, the MR curves differ depending on whether the magnetic field is parallel to the current direction, that is, the longitudinal direction of the element, or when the magnetic field is orthogonal.

  Further, for example, as shown in FIG. 4 of Patent Document 1, the MR curve of the GMR element has a hysteresis characteristic like the AMR element. Therefore, as shown in FIG. 8 of Patent Document 1, by using a bias magnetic field generated by flowing a bias current through the GMR element, the magnetic field change region applied to the GMR element as the magnetic drum rotates is changed to the GMR element. The magnetic field region that does not have the hysteresis characteristic is taken.

JP-A-8-68661

  However, in order to reduce the influence of the hysteresis characteristics of the MR element on the output signal waveform of the magnetic position detection device, when using the above-described magnet or a bias magnetic field generated by a bias current, a magnet or the like is provided separately. Since power supply is required, the points of miniaturization and low power consumption are raised.

  The present invention has been made to solve such problems, and is effective for downsizing and low power consumption, and can detect the moving amount and position of a moving body with high accuracy. An object is to provide an apparatus.

In order to achieve the above object, the present invention is configured as follows.
That is, a magnetic position detection device according to an aspect of the present invention includes a magnetized member having a magnetized region in which N and S poles are alternately magnetized at a magnetizing pitch λ, and the magnetizing pitch λ. A magnetic position detecting device comprising: a magnetic sensor whose output changes depending on the angle and strength of the magnetic field acting on the magnetic pole in the magnetized region by relative movement with the magnetized member along the arrangement direction of the magnetic pole The magnetic sensor includes a magnetoelectric conversion element that is disposed in a non-contact manner on the magnetized member at a bias application position deviating from a center position of the magnetized region in a direction perpendicular to the arrangement direction of the magnetic poles. And

  According to the magnetic position detection device of one aspect of the present invention, the magnetoelectric conversion element included in the magnetic sensor is applied to the magnetized member at a bias application position deviating from the center position of the magnetized region in the direction perpendicular to the magnetic pole arrangement direction. Arranged without contact. According to this configuration, the change in the magnetic field strength applied to the magnetic sensor with the relative movement between the magnetized member and the magnetic sensor becomes a sine wave on which a DC bias magnetic field is superimposed. That is, the DC bias magnetic field can be superimposed only by the arrangement of the magnetoelectric transducer, whereas the DC bias is superimposed by using a magnet or a bias magnetic field generated by a bias current. By superimposing the DC bias magnetic field, distortion in the output signal waveform of the magnetic position detection device can be reduced. Furthermore, since a magnet or the like is not separately provided and power supply is not required, a highly accurate magnetic position detection device can be realized with a small size and low power consumption.

  A magnetic position detection apparatus according to an embodiment of the present invention will be described below with reference to the drawings. In each figure, the same or similar components are denoted by the same reference numerals.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a magnetic position detection device 101 according to Embodiment 1 of the present invention. The magnetic position detection apparatus 101 includes a magnetic drum 111 corresponding to an example of a magnetized member and a magnetic sensor 102 as basic components, and outputs an electrical signal from the magnetic sensor 102 as the magnetic drum 111 rotates. Based on the output signal that is output, the detection device 121 detects the amount and position of movement of the magnetic drum 111.

  The magnetic drum 111 has a disk shape, and has a magnetized region 112 in which N and S magnetic poles are alternately magnetized at a magnetizing pitch λ per pole on the outer peripheral portion. Is rotated in the circumferential direction y. Such a magnetic drum 111 is connected to a measurement object whose rotational movement amount and position are to be detected. In the z direction, which is the axial direction of the rotating shaft 113, the length of the magnetized region 112 is a distance d. As shown in the figure, in the magnetic drum 111 of the first embodiment, the distance d and the thickness of the disk portion of the magnetic drum 111 are the same size. In the magnetic drum 111 as a rotating body, the arrangement direction of the N-pole and S-pole magnetic poles corresponds to the circumferential direction y. The radial direction of the magnetic drum 111 is the x direction. Further, “51” shown in FIG. 1 indicates a position that is ½ of the distance d of the magnetized region 112 in the z direction, and corresponds to the center position of the magnetized region 112. Hereinafter, the center position 51 is described.

  As described above, in this embodiment, the rotating member of the magnetic drum 111 is taken as an example of the magnetizing member, but the magnetizing member is not limited to this form. For example, the magnetized member may be a flat plate-like member, and the magnetic poles may be alternately magnetized in the linear magnetic pole arrangement direction along the longitudinal direction thereof. In this embodiment, the magnetic drum 111 is rotated and the magnetic sensor 102 is fixed, but the magnetized member and the magnetic sensor move relative to each other along the magnetic pole arrangement direction. Can be configured.

  The magnetic sensor 102 includes a magnetoresistive element 104 that changes the resistance value of the element due to a change in the magnetic field, as an example of a magnetoelectric conversion element that detects a magnetic field and outputs an electrical signal. In the present embodiment, for example, a stripe-shaped exchange coupling type giant magnetoresistive element (hereinafter referred to as “GMR element”) is used as the magnetoresistive element 104 and has no shape anisotropy. Is used. In the GMR element 104, the MR curve of the GMR element with respect to the direction of the magnetic field applied to the element is isotropic. Here, the MR curve means the characteristic of resistance change with respect to the magnetic field of the element as described above.

  Such a GMR element 104 is formed on a glass substrate, for example, by a thin film process. In the first embodiment, as shown in FIG. 2, one end portion 104 a of one GMR element 104 is formed to be separated from the center point 52 of the magnetic sensor 102 by a distance d / 2. Here, d is the distance d of the magnetized region 112 in the z direction described above.

  As shown in FIGS. 1 and 3, the magnetic sensor 102 having the GMR elements 104 arranged as described above has the GMR element forming surface 102 a of the magnetic sensor 102 parallel to the z direction as shown in FIGS. 1 and 3. In the z direction, the center point 52 of the magnetic sensor 102 and the center position 51 of the magnetized region 112 are made to coincide and face each other, and are arranged in a non-contact manner.

The operation of the magnetic position detection apparatus 101 of the present embodiment configured as described above will be described.
Changes in the magnetic field strength applied to the magnetic sensor 102 with the rotation of the magnetic drum 111 include the distance between the magnetic drum 111 and the magnetic sensor 102, the magnetization pitch λ of the magnetic drum 111, and the magnetic medium in the magnetized region 112. Depends on the parameters of the material and magnetic properties. In the first embodiment, the change in the magnetic field strength at the position facing the center position 51 of the magnetized region 112 in the magnetic drum 111, that is, the center point 52 of the magnetic sensor 102, is ideal. It is assumed that the above-described parameters are optimized so as to approach a sine wave.

  FIG. 4 shows a simulation of a part of the magnetic field generated from the magnetic drum 111. Focusing on the magnetic field component generated by the magnetic drum 111, the magnetic field component exists only in the x direction and the y direction at the central position 51 of the magnetized region 112 in the magnetic drum 111. On the other hand, at the end portions 112a and 112b of the magnetized region 112 in the z direction, the magnetic field wraps around, so that the magnetic field component exists not only in the x and y directions but also in the z direction. Further, when the GMR element 104 is arranged in close contact with the magnetic drum 111 in a non-contact manner, magnetic field components that affect the resistance change of the GMR element 104 are the y direction and the z direction. That is, the strength of the magnetic field applied to the GMR element 104 needs to consider the synthesis of each magnetic field component in the y direction and the z direction, which are the magnetic sensing directions, and also consider the angle formed by the synthesized magnetic field with the GMR element 104. There is a need.

  Here, when the GMR element 104 is disposed in a non-contact manner at a position facing the center position 51 of the magnetized region 112 in the magnetic drum 111, changes in magnetic field components in the y direction and the z direction applied to the GMR element 104 are changed. FIG. 5 shows a simulation. On the other hand, FIG. 6 shows a simulation of changes in the y-direction and z-direction magnetic field components applied to the GMR element 104 disposed facing the end 112a or the end 112b of the magnetized region 112. FIG. Here, the arrangement of the GMR element 104 facing the end 112a or the end 112b of the magnetized region 112 is, for example, the end of the magnetized region 112 as described with reference to FIG. In the case where the GMR element 104 is disposed so as to face the surface 112a, this means an arrangement in which the one end 104a of the GMR element 104 is aligned with the end surface 112a-1 (FIG. 4) of the end 112a of the magnetized region 112. Similarly, when the GMR element 104 is disposed to face the end 112b of the magnetized region 112, one end 104b (FIG. 2) of the GMR element 104 is connected to the end surface 112b− of the end 112b of the magnetized region 112. 1 (FIG. 4).

  Further, when the magnetic field components in the y direction and the z direction are combined and output as a change in the magnetic field strength, the change in the magnetic field strength applied to the GMR element 104 disposed facing the center position 51 of the magnetized region 112 is: The change in the magnetic field strength applied to the GMR element 104 arranged as shown in FIG. 7 and facing the end 112a or 112b of the magnetized region 112 is as shown in FIG. Further, as the magnetic drum 111 rotates, not only does the magnetic field intensity applied to the GMR element 104 change as indicated by the arrow 115a in FIG. 9, but also the GMR element as indicated by the arrow 115b in FIG. The direction of the magnetic field applied to 104 also rotates.

  In view of the change in magnetic field strength shown in FIGS. 7 and 8, the magnetization region corresponds to the change in the magnetic field strength applied to the GMR element 104 disposed opposite to the central position 51 of the magnetization region 112 in the magnetic drum 111. The change in the magnetic field strength applied to the GMR element 104 disposed opposite to the end 112a or the end 112b of the magnetized region 112, which is away from the center position 51 of the 112 in the z direction, is superimposed on the DC bias magnetic field. ing.

  In the present embodiment, as described above, the magnetic sensor 102 has one GMR element 104 so as to face the end 112a or 112b of the magnetized region 112, but is not limited thereto. A configuration in which two GMR elements 104 are arranged along the z direction so as to face both ends 112a and 112b of the magnetized region 112 may be employed.

In the present embodiment, as described above, the magnetic sensor 102 is arranged so that, for example, one end 104a of the GMR element 104 coincides with the end surface 112a-1 of the end 112a of the magnetized region 112. However, the position of the GMR element 104 with respect to the magnetized region 112 in the z direction is not limited to the case of the present embodiment, and the direction perpendicular to the magnetic pole arrangement direction (the y direction in the present embodiment) (the z direction in the present embodiment). ), Any bias application position that deviates from the center position 51 of the magnetized region 112 may be used. That is, as described above, any position where a DC bias is applied to the GMR element 104 may be used, and the position in the z direction is not particularly limited.
In addition, since the MR curve of the GMR element 104 according to the first embodiment is isotropic with respect to the applied magnetic field angle, it is not necessary to consider the application direction of the magnetic field.

As described above, according to the magnetic position detection apparatus 101 of the first embodiment, the GMR element 104 is contactlessly disposed at a position facing the vicinity of the end portions 112a and 112b of the magnetized region 112 in the magnetic drum 111. By arranging them close to each other, the change in magnetic field strength applied to the GMR element 104 with the rotation of the magnetic drum 111 becomes a sine wave on which a DC bias magnetic field is superimposed. That is, conventionally, a DC bias is superimposed on the output signal of the magnetoelectric conversion element by using a magnet or a bias magnetic field generated by a bias current, but only by defining the arrangement position of the GMR element 104. A DC bias magnetic field can be superimposed. Thus, by superimposing the DC bias on the output signal of the GMR element 104, distortion in the output signal waveform of the magnetic position detection device 101 can be reduced.
Therefore, it is possible to provide a magnetic position detection device capable of detecting the position of the measurement object with high accuracy, and in this magnetic position detection device, other components such as magnets are provided. In addition, it is possible to realize a magnetic position detection device 101 that is small and has low power consumption without the need for power supply.

  The bias magnetic field strength superimposed here can be realized by optimizing the distance between the magnetic drum 111 and the magnetic sensor 102, the magnetization pitch λ in the magnetic drum 111, the material of the magnetic medium in the magnetized region 112, and the magnetic characteristics. is there.

Embodiment 2. FIG.
In the first embodiment described above, the magnetic sensor 102 has a configuration having one GMR element 104. On the other hand, in the second embodiment described below, as shown in FIGS. 10 to 13, a configuration in which the magnetic sensor has a plurality of GMR elements is shown. Except for the configuration in which the magnetic sensor has a plurality of GMR elements, the other configurations in the second embodiment are the same as those in the first embodiment. Therefore, only different components will be described below.

In the configuration shown in FIG. 10, the magnetic sensor 103 corresponding to the magnetic sensor 102 in the first embodiment described above has two GMR elements 104-1 and 104-2. The GMR elements 104-1 and 104-2 correspond to the GMR element 104 in the first embodiment described above.
As shown in FIG. 10, the GMR elements 104-1 and 104-2 are arranged at a distance λ so as to be symmetrical with respect to the center point 52 of the magnetic sensor 103 in the magnetic pole arrangement direction. Here, λ is a dimension equal to the above-mentioned magnetization pitch λ. Similarly to the configuration in the first embodiment, as one arrangement example, the GMR elements 104-1 and 104-2 are arranged such that each end 104a of the GMR elements 104-1 and 104-2 is in the z direction. The center point 52 is disposed so as to be separated by a distance d / 2 upward. The magnetic sensor 103 having such a configuration is arranged in parallel to the z direction as in the case of the magnetic sensor 102, and as shown in FIG. 11, the center point 52 of the magnetic sensor 103 and the magnetized region in the magnetic drum 111. The center position 51 of 112 is made to correspond in the z direction and is opposed to the magnetized region 112 in front, and is arranged in a non-contact manner.

  In the magnetic sensor 103, the interval between the GMR elements 104-1 and 104-2 arranged symmetrically is not limited to λ, but may be a distance of (2n + 1) λ (n: integer). In this case, the magnetization pitch of the magnetic poles in the magnetized region 112 is also changed correspondingly.

  In the magnetic position detection apparatus according to the second embodiment provided with the magnetic sensor 103 described above, the change in the magnetic field applied to each of the GMR elements 104-1 and 104-2 with the rotation of the magnetic drum 111 is the y direction. Since the arrangement interval and the magnetization pitch of the GMR elements 104-1 and 104-2 are equal to each other at the distance λ, the GMR elements 104-1 and 104-2 are out of phase with each other. On the other hand, since the MR curves of the GMR elements 104-1 and 104-2 are substantially even functions, the output signal waveforms of the GMR elements 104-1 and 104-2 are in phase with each other, not limited to the polarity of the magnetic field. That is, by adding the output signal waveforms of the GMR elements 104-1 and 104-2, the influence of the hysteresis phenomenon such that the resistance change varies depending on the polarity of the magnetic field in the GMR elements 104-1 and 104-2 can be reduced. Can do. Therefore, the magnetic position detection device according to the second embodiment can perform position detection with higher accuracy than the magnetic position detection device 101 according to the first embodiment. In the second embodiment, the detection device 121 connected to the magnetic sensor 103 is provided with an adding unit that adds the output signal waveforms of the GMR elements 104-1 and 104-2.

  Further, FIG. 10 shows a configuration in which the GMR elements 104-1 and 104-2 are arranged on the upper side of the magnetized region 112 in the figure. As a modification of the configuration, each end of each of the GMR elements 104-1 and 104-2 is shown. The GMR elements 104-1 and 104-2 can be arranged on the lower side of the magnetized region 112 in the drawing with the portion 104 b aligned with the end face 112 b-1 of the magnetized region 112.

  Furthermore, as a modification of the configuration shown in FIGS. 10 and 11, as shown in FIG. 12, the GMR elements 104-1 and 104-2 are placed diagonally about the center point 52 of the magnetic sensor 103-1. Alternatively, a total of four GMR elements 104 may be arranged by adding GMR elements 104-3 and 104-4 as in the magnetic sensor 103-2 shown in FIG.

  Also in the configuration in which each GMR element 104 is arranged as shown in FIGS. 12 and 13, the hysteresis phenomenon can be reduced by adding the output signal waveforms of each GMR element 104, and high accuracy can be achieved as well. Can be realized.

  Further, in the configuration shown in FIGS. 10 to 13, the number of GMR elements 104 may be an even number of 4 or more.

  Further, the interval between the GMR elements 104 described above is not limited to the above-mentioned λ, and may be a distance of (2n + 1) λ (n: integer), and the position where each GMR element 104 is disposed is the bias application position. What is necessary is also applicable to the configuration shown in FIGS.

1 is a perspective view showing an overall configuration of a magnetic position detection device according to Embodiment 1 of the present invention. It is a front view of the magnetic sensor shown in FIG. It is a figure for demonstrating the arrangement | positioning relationship between the magnetization area | region shown in FIG. 1, and a magnetic sensor. It is a figure for demonstrating the magnetic field generated from the magnetic pole of the magnetization area | region in the magnetic drum shown in FIG. It is a figure for demonstrating the change of the magnetic field component of the y direction applied to a GMR element, and a z direction, when a GMR element is arrange | positioned in the position facing the center position of the magnetization area | region. It is a figure for demonstrating the change of the magnetic field component of the y direction applied to a GMR element, and a z direction when a GMR element is arrange | positioned in the position facing the edge part of the magnetization area | region in non-contact. It is a figure for demonstrating the change of the magnetic field intensity applied to a GMR element, when a GMR element is arrange | positioned non-contactingly in the position facing the center position of the magnetization area | region. It is a figure for demonstrating the change of the magnetic field intensity applied to a GMR element when the GMR element is arrange | positioned in the position facing the edge part of the magnetization area | region in non-contact. It is a figure for demonstrating the direction change of the magnetic field applied to a GMR element, when a GMR element is arrange | positioned in the position facing the edge part of the magnetization area | region in non-contact. It is a front view of the magnetic sensor with which the magnetic position detection apparatus in Embodiment 2 of this invention is equipped. It is a figure for demonstrating the arrangement | positioning relationship between the magnetic drum and magnetic sensor in the magnetic-type position detection apparatus shown in FIG. It is a front view which shows an example of the modification of the magnetic sensor in the magnetic position detection apparatus shown in FIG. It is a front view which shows the other example of the modification of the magnetic sensor in the magnetic position detection apparatus shown in FIG.

Explanation of symbols

51 center position, 52 center point,
101 magnetic position detecting device, 102, 103, 103-1, 103-2 magnetic sensor,
104, 104-1, 104-2 GMR element,
111 magnetic drum, 112 magnetized region, 112a, 112b end.

Claims (4)

Relative between a magnetized member having a magnetized region in which N poles and S poles are alternately magnetized at a magnetized pitch λ, and the magnetized member along the arrangement direction of the magnetic poles at the magnetized pitch λ In a magnetic position detection device comprising a magnetic sensor whose output changes depending on the angle and strength of the magnetic field acting on the magnetic poles of the magnetized region by a simple movement,
The magnetic sensor includes a magnetoelectric conversion element that is disposed in a non-contact manner on the magnetized member at a bias application position deviating from a center position of the magnetized region in a direction perpendicular to the arrangement direction of the magnetic poles. Magnetic position detector.   2. The bias application position is a position corresponding to an end portion of the magnetized region in the perpendicular direction in which a bias magnetic field that reduces hysteresis characteristics of the magnetoelectric conversion element is applied to the magnetoelectric conversion element. Magnetic position detector.   3. The magnetic type according to claim 1, wherein 2 m (m: integer) of the magnetoelectric conversion elements are arranged at a distance λ or (2n + 1) λ (n: integer) apart from each other along the arrangement direction of the magnetic poles. Position detection device.   The magnetized member is a magnetic drum that is disk-shaped and has the magnetized region around the entire circumference along the circumferential direction and rotates about a rotation axis. The magnetic sensor is disposed to face the magnetic region. The magnetic position detecting device according to any one of claims 1 to 3, wherein the magnetoelectric conversion element is a magnetoresistive element.

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