JP4912595B2 - Position detection device - Google Patents

Description

  The present invention relates to a position detection device such as an absolute magnetic encoder having a magnetized magnetic track.

  As a conventional absolute magnetic encoder, a magnetic field from a magnetic recording medium (magnetic track) in which at least one magnetization pattern array having a magnetization intensity distribution is written is used as at least one stripe-shaped magnetism close to the recording medium. In an absolute magnetic encoder that detects the absolute position (angular position) of the detected object (moving body, rotating body) based on the magnitude of the output value detected by the resistance effect element, the stripe length direction of the magnetoresistive effect element is the magnetic recording There is an absolute magnetic encoder characterized in that the stripe width direction is substantially perpendicular to the medium surface, the stripe width direction is parallel to the magnetization pattern row direction, and a magnetic field from the magnetization pattern is applied in the stripe width direction (see, for example, Patent Document 1). ).

  Further, a magnetic medium (magnetic track) having first and second members that move relative to each other, and a magnetomotive member that is provided on the first member (moving body, rotating body) and recorded at a recording pitch λ in the relative movement direction. ) And a magnetic sensor provided with a magnetoresistive effect element that is provided on the second member and is sensitive to the magnetic field of the magnetomotive body, and changes in accordance with the relative movement of the first and second members. In the case where the absolute position (angular position) between the two members is detected by the electrical signal of the resistance effect element, the width of the magnetomotive member recorded on the magnetic medium is changed according to the relative movement direction, and the first and second There is an absolute position detecting device configured to detect a deviation amount between the first and second members based on an output signal of the magnetoresistive effect element that changes in an analog manner according to relative movement of the first member (for example, See Patent Document 2).

  The conventional (rotational) position detection device for magnetically detecting the position of a moving body (rotating body) is a moving body (rotating body) having a magnetic track that is magnetized and generates a magnetic field that changes with the movement, And a magnetoresistive effect element for detecting a change.

JP-A-63-206613 JP-A-64-032117

  However, in the conventional position detecting device including the above-described magnetic track, it is necessary to change the magnetization length in the width direction depending on the position in the length direction (circumferential position) of the magnetic track when the magnetic track is manufactured. While moving the track precisely in the length direction (circumferential direction) by a predetermined pitch, the magnetizing length in the width direction must be changed slightly each time, and a highly accurate magnetized track is produced. It was not easy. In addition, there is a problem that it is difficult to manufacture a magnetic track that generates a magnetic field that changes in a complicated manner.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a highly accurate position detection device that can be easily manufactured.

In order to solve the above-described problems and achieve the object, a position detection device of the present invention includes a rotating body having a rotating shaft and a columnar or cylindrical base supported by the rotating shaft, and the rotating body of the rotating body. A cylindrical magnetic track which is arranged on the circumferential surface of the base and is NS magnetized with a uniform width and strength so that adjacent magnetic poles are the same magnetic pole at a predetermined pitch in the circumferential direction; A magnetic flux collecting member, which is arranged so as to cover a part of the magnetic track in the width direction and is made of a ring-shaped ferromagnetic film having a different width depending on the circumferential position of the magnetic track, and opposed to the circumferential surface of the magnetic track And a magnetic detection element that outputs a magnetic strength signal in response to a nearby magnetic field strength, and detects a rotational angle position of the rotating body.

  According to the present invention, a cylindrical magnetic track which is NS magnetized with a uniform width and strength so that adjacent magnetic poles are the same magnetic pole at a predetermined pitch in the circumferential direction, and one of the magnetic tracks. A magnetic current collecting member that is arranged so as to cover a portion and has a ring-shaped magnetic flux collecting member having a different width depending on the circumferential position of the magnetic track. It can be easily manufactured.

  According to the present invention, it is possible to easily manufacture a rotating body having a magnetic track that accurately changes the generated magnetic field intensity according to the circumferential position of the magnetic track, and to obtain a position detection device with high position detection accuracy and low manufacturing cost. There is an effect that can be.

  Embodiments of a position detection apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a perspective view showing a position detection apparatus according to Embodiment 1 of the present invention, and FIG. 2 is a development in which the cylindrical magnetic track 4 and the magnetic flux collecting member 5 shown in FIG. FIG. 3 is a top view of the rotating body 1, and FIG. 4 is a longitudinal sectional view of the rotating body 1.

  The rotating body 1 includes a rotating shaft 2 and a columnar base 3 having a width H and a circumferential length L supported by the rotating shaft 2. The rotating shaft 2 and the base 3 are preferably made of a nonmagnetic material such as aluminum or SUS. The shape of the base 3 may be a hollow cylindrical shape having end plates, and any shape can be used as long as the cylindrical magnetic track 4 can be supported with the rotary shaft 2 as an axis. Good.

  On the circumferential surface of the base 3, a magnetic track 4 made of a resin material mixed with magnetic powder is formed and installed in a cylindrical shape having a width H and a circumferential length L. As the resin material, it is preferable to use an engineering plastic such as PPS in consideration of heat resistance. The magnetic track 4 performs NS magnetization with a uniform strength over the entire circumference L and a uniform width H so that adjacent magnetic poles have the same polarity at a predetermined equal pitch λ in the circumferential direction. .

  On the outer peripheral surface of the magnetic track 4 made of resin material, a ferromagnetic film 5 as a ring-shaped magnetic collecting member, which is a member different from the magnetic track 4, covers a part of the magnetic track 4 in the width direction. Is formed. The ferromagnetic film 5 is made of a ferromagnetic material. As the ferromagnetic material, for example, permalloy, silicon steel plate, ferrite or the like may be used, but considering the mass balance of the rotating body 1, it is desirable to use an amorphous alloy having a thin film shape and high magnetic permeability. The ring-shaped ferromagnetic film 5 is formed so that its width varies depending on the circumferential position of the magnetic track 4.

  Part of the magnetic track 4 in the width direction, which is NS magnetized with a uniform width H, is covered with a ring-shaped ferromagnetic film 5 having a different width depending on the position in the circumferential direction. The collected magnetic flux lines are collected by the ferromagnetic material 5 so that the magnetic flux lines do not leak outside the ferromagnetic film 5. Therefore, the magnetic field intensity generated by the magnetic track 4 varies depending on the circumferential position.

  The thickness of the NS magnetized magnetic track 4 is preferably about 2 mm, for example, but may be set to an appropriate thickness in consideration of the outer diameter of the base 3 and the like. Further, although the thickness of the ferromagnetic film 5 is shown in FIG. 3 as the same thickness as the magnetic track 4, the thickness is different depending on the position in the circumferential direction. In view of the above, it is desirable to improve the rotational position detection accuracy by making the thin film as thin as possible and keeping the mass balance of the rotator 1 intact. The ferromagnetic film 5 as the magnetic flux collecting member may be formed by applying a liquid having ferromagnetic characteristics to the magnetic track 4 and solidifying it.

  As shown in FIGS. 1, 2, and 4, the width of the ferromagnetic film 5 varies depending on the circumferential position of the rotating body 1. Although the generated magnetic flux 8 is schematically shown in FIG. 4, the generated magnetic flux 8 decreases in proportion to the width of the ferromagnetic film 5 covering the magnetic track 4 due to the magnetic flux collecting effect of the ferromagnetic film 5.

  When the mass balance of the rotating body 1 is lost, a mass removing unit 12 that removes part of the mass of the base 3 or a mass adding unit 13 that adds mass to the base 3 is provided, and the mass balance of the rotating body 1 is increased. Adjust it.

  As the magnetic detection element 6, for example, a magnetoelectric conversion element such as a magnetoresistive effect element (MR element) that changes the electric resistance in response to the magnetic intensity in the vicinity of itself and outputs a magnetic intensity signal is used. The magnetic detection element 6 is installed so as to face the circumferential surface of the magnetic track 4 with a minute gap. An arithmetic processing circuit 7 is connected to the magnetic detection element 6, and the magnetic field intensity in the vicinity of the magnetic detection element 6 is changed according to the circumferential displacement of the magnetic track 4 accompanying the rotational displacement of the rotating body 1, and is sensitive to this. The magnetic intensity signal output from the magnetic detection element 6 is processed, and the rotational angle position of the rotating body 1 is calculated and output.

  In the first embodiment, a magnetoelectric conversion element such as a magnetoresistive effect element is used as the magnetic detection element 6, but the magnetic detection element 6 is not limited to the magnetoresistive effect element, and the magnetization pitch For example, a Hall element, an MI element, or the like may be used as long as the device has a dimension that can handle λ.

  The magnetic detection element 6 outputs a signal having a wavelength corresponding to the magnetization pitch of the magnetic track 4, and adds both the signal and a signal whose phase is inverted, so that the magnetic detection element 6 changes with the circumferential displacement of the magnetic track 4. The magnetic field strength to be detected is detected. In the first embodiment, since the width of the ferromagnetic film 5 is linearly changed, the detected magnetic field intensity also changes linearly, but the shape of the ferromagnetic film 5 is easy. For example, it can be formed so as to obtain a desired waveform signal such as a sine wave shape.

  In the first embodiment described above, the magnetic track 4 is NS magnetized with a uniform width H and strength so that adjacent magnetic poles are the same magnetic pole at a predetermined pitch λ in the circumferential direction. Since a part of the magnetic track 4 in the width direction is covered with the ring-shaped ferromagnetic film 5 whose width is changed according to the circumferential position of the magnetic track 4 on the magnetic track 4 after magnetization, the circumferential direction of the magnetic track 4 The magnetic track 4 in which the generated magnetic field strength is precisely changed depending on the position can be easily manufactured.

  Further, by changing the shape of the ferromagnetic film 5, a desired waveform signal can be obtained without changing the NS magnetization pattern of the magnetic track 4.

  Further, it is possible to easily manufacture the rotating body 1 having the magnetic track 4 that precisely changes the generated magnetic field intensity according to the circumferential position of the magnetic track 4, and to obtain a position detection device with high position detection accuracy and low manufacturing cost. There is an effect that can be.

Embodiment 2. FIG.
FIG. 5 is a perspective view showing a position detection device according to Embodiment 2 of the present invention, and FIG. 6 is a longitudinal sectional view of the rotating body 1. In FIG. 5, the magnetic detection element and the arithmetic processing circuit are not shown. 5 and 6, the same components as those shown in FIGS. 1 to 4 are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIGS. 5 and 6, a ring-shaped nonmagnetic member 10 as a magnetic transmission member is formed and arranged so as to cover the outer peripheral surface of the magnetic track 4 that is not covered with the magnetic collecting member 5. The nonmagnetic member 10 is installed so that the total mass per unit area of the magnetism collecting member 5 and the nonmagnetic member 10 facing each other with the rotating shaft 2 interposed therebetween is equal, and the mass balance of the rotating body 1 is maintained. Therefore, the nonmagnetic member 10 does not need to completely cover the portion of the magnetic track 4 that is not covered with the magnetic collecting member 5, and is adjusted and arranged so as to balance the mass of the rotating body 1. In order to balance the mass of the rotating body 1, the nonmagnetic member 10 may be arranged so as to extend to the outer peripheral portion of the magnetic flux collecting member 5 and cover a part of the outer peripheral portion.

  When a member having a large mass such as a bulk material is used as the magnetic flux collecting member 5 instead of a thin film, the mass balance of the rotating body 1 is greatly broken. Therefore, it is necessary to install the nonmagnetic member 10 in order to maintain the mass balance. Although the generated magnetic flux 8 is schematically shown in FIG. 6, the generated magnetic flux 8 decreases in proportion to the width of the magnetic collecting means 5 covering the magnetic track 4 due to the magnetic collecting effect of the magnetic collecting means 5. Passes through the nonmagnetic member 10 and is released to the outside.

  In addition, after the adjustment of the mass balance of the rotating body 1 by the installation of the nonmagnetic member 10, when the mass balance needs to be further finely adjusted, the mass removing unit 12 from which a part of the mass of the base 3 is removed, It is also possible to finely adjust the mass balance of the rotating body 1 by providing a mass adding portion 13 that adds mass to the table 3.

  In the second embodiment described above, the rotating body 1 having a mass balance can be obtained by installing the non-magnetic member 10, so that the mass can be obtained at any rotation regardless of whether the rotating body 1 rotates at high speed or low speed. Therefore, the rotation position detection apparatus with high position detection accuracy can be obtained.

Embodiment 3 FIG.
FIG. 7 is a longitudinal sectional view showing the rotating body 1 of the position detection device according to the third embodiment. In FIG. 7, the magnetic detection element and the arithmetic processing circuit are not shown. In FIG. 7, the same components as those shown in FIGS. 1 to 6 are denoted by the same reference numerals, and redundant description is omitted.

  The outer peripheral surfaces of the magnetic flux collecting member 5 and the magnetic transmission member 10 arranged on the outer peripheral surface of the magnetic track 4 are covered with a protective member 11 made of a magnetic transmission material. The protective member 11 is installed for the purpose of preventing the magnetic track 4, the magnetic flux collecting member 5 and the magnetic transmission member 10 from being broken by the centrifugal force during the rotation of the rotating body 1 and from being damaged by the external environment. .

  The protection member 11 is formed, for example, by applying a resin material to the outer peripheral surfaces of the magnetic flux collecting member 5 and the magnetic transmission member 10 and solidifying it, or by fitting a nonmagnetic metal cylinder. The protection member 11 protects the magnetic track 4, the magnetic flux collecting member 5, and the magnetic transmission member 10 without changing the magnetic field distribution on the outer peripheral portion of the rotating body 1. In addition, the protection member 11 may cover not only the outer peripheral surface of the rotating body 1 but also the upper surface and the lower surface of the rotating body 1 (base 3).

  The protection member 11 is installed so that the mass distribution is uniform over the entire circumference so that mass unbalance does not occur in the rotating body 1 due to the installation of the protection member 11.

  Further, when it is necessary to finely adjust the mass balance, a mass removing unit 12 that removes a part of the mass of the base 3 or a mass adding unit 13 that adds mass to the base 3 is provided. It is also possible to finely adjust the mass balance.

  In the third embodiment described above, since the rotating body 1 is protected by the installation of the protection member 11, the position detection can be performed with high accuracy over a long period of time without being affected by the external environment. A device is obtained.

  In the first to third embodiments, the rotation position detection device that rotates the rotating body 1 relative to the magnetic detection element 6 and detects the rotation angle position is shown. However, the position detection device is linearly displaced. And a flat magnetic track arranged on the moving body and NS-magnetized with uniform width and strength so that adjacent magnetic poles are the same magnetic pole with a predetermined pitch in the length direction, A magnetic flux collecting member which is disposed so as to cover a part of the magnetic track and has a width different depending on the position in the length direction of the magnetic track, and is disposed so as to face the surface of the magnetic track. And a magnetic detection element that outputs a magnetic intensity signal in response to the linear position detection device that detects the displacement position of the moving body.

  In the linear position detection apparatus configured as described above, the magnetic track is NS magnetized with a uniform width and strength so that adjacent magnetic poles have the same magnetic pole at a predetermined pitch in the length direction, and NS Since a part of the magnetic track in the width direction is covered with a band-shaped magnetic flux collecting member whose width varies depending on the position in the length direction of the magnetic track, the magnetic field generated by the position in the length direction of the magnetic track is covered. Magnetic tracks that change the strength precisely can be easily manufactured.

  Further, by changing the shape of the magnetic flux collecting member, a desired waveform signal can be obtained without changing the NS magnetization pattern of the magnetic track.

  Further, it is possible to easily manufacture a moving body having a magnetic track that precisely changes the generated magnetic field intensity depending on the position in the length direction of the magnetic track, and to obtain a linear position detection device with high position detection accuracy and low manufacturing cost. There is an effect.

  As described above, the position detection device according to the present invention can be used in place of a conventional position detection device as a highly accurate position detection device that can be easily manufactured at low cost.

It is a perspective view which shows the position detection apparatus of Embodiment 1 of this invention. FIG. 4 is a development view showing a magnetic track and a ferromagnetic film developed in a plane. It is a top view of a rotary body. It is a longitudinal cross-sectional view of a rotary body. It is a perspective view which shows the position detection apparatus of Embodiment 2 of this invention. It is a longitudinal cross-sectional view of a rotary body. It is a longitudinal cross-sectional view which shows the rotary body of the magnetic detection apparatus of Embodiment 3 of this invention.

Explanation of symbols

1 Rotating body 2 Rotating shaft 3 Base 4 Magnetic track 5 Ferromagnetic film (magnetic collecting member)
6 Magnetic sensing element (magnetoresistance effect element)
7 Arithmetic processing circuit 8 Generated magnetic flux 10 Non-magnetic member (magnetic transmission member)
11 Protection member 12 Mass removal part 13 Mass addition part

Claims (5)

A rotating body having a rotating shaft and a columnar or cylindrical base supported by the rotating shaft;
A cylindrical shape which is arranged on the circumferential surface of the base of the rotating body and is NS magnetized with a uniform width and strength so that adjacent magnetic poles are the same magnetic pole at a predetermined pitch in the circumferential direction. Magnetic track,
A magnetic flux collecting member that is arranged so as to cover a part in the width direction of the magnetic track, and is formed of a ring-shaped ferromagnetic film having a different width depending on a circumferential position of the magnetic track;
A magnetic detecting element that is installed so as to face the circumferential surface of the magnetic track and outputs a magnetic strength signal in response to a magnetic field strength in the vicinity;
A position detecting device for detecting a rotation angle position of the rotating body. The position detecting device according to claim 1 , wherein the ferromagnetic film is formed by applying a liquid having ferromagnetic characteristics to the magnetic track and solidifying the magnetic track. Wherein the collector is not covered with the magnetic member portion of the magnetic track, the position detecting device according to claim 1 or 2, characterized in that it has established a magnetically permeable member for establishing mass balance of the rotating body. The position detection device according to claim 3 , wherein outer peripheral surfaces of the magnetic flux collecting member and the magnetic transmission member are covered with a protective member that transmits magnetism. A moving body that is linearly displaced;
A flat magnetic track disposed on the moving body and NS-magnetized with a uniform width and strength so that adjacent magnetic poles are the same magnetic pole at a predetermined pitch in the length direction;
A magnetic flux collecting member that is arranged so as to cover a part in the width direction of the magnetic track, and is formed of a strip-shaped ferromagnetic film having a different width depending on the position in the length direction of the magnetic track;
A magnetic detection element installed to face the surface of the magnetic track, and outputs a magnetic intensity signal in response to a magnetic field intensity in the vicinity;
And a position detecting device for detecting a displacement position of the moving body.

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