JP2016144257A - Magnet device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnet device capable of moving a movable member to a predetermined position with high accuracy and reducing a size and a weight.SOLUTION: A magnet device includes: a driving magnet 11 disposed to a fixing member 2, and a movable coil 13 disposed to a movable member 5, and the driving magnet 11 includes: a voice coil motor 9 to which a heteropolar magnetic pole is adjacent along with a moving direction of the movable member 5; a holding member 4 that is connected to the fixing member 2 with a predetermined interval so as to opposite to the movable member 5; a spherical body 6 interposed between the holding member 4 and the movable member 5 at a position opposite to the driving magnet 11; a detection magnet 16 that is arranged to the movable member 5 and to which the heteropolar magnetic pole is adjacent along with its moving direction; a position detection member 14 that faces to the detection magnet 16 and has a magnetic field detection element 15 that is arranged in the holding member 4; a first yoke 8A that is arranged in the holding member 4 and to which a magnetic flux generated from the driving magnet 11 flows; and a second yoke 8B to which the magnetic flux generated from the detection magnet 16 flows.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a magnet device including a position detection member including a voice coil motor and a magnetic field detection element that linearly moves a movable member with respect to a fixed member.

  In precision instruments such as digital cameras, such as digital cameras, for example, optical camera shake correction devices are attached to camera bodies and interchangeable lenses in order to take high-quality pictures as the taking lens becomes longer in focus or zoomed in at a higher magnification. It has become common to install. In an optical camera shake correction device, a correction lens or an image sensor is moved in a two-dimensional direction by a voice coil motor (hereinafter referred to as “VCM”) on a plane perpendicular to the optical axis, and a position detection device is mounted on the servo. It is common to control.

  For example, in Patent Document 1, a first member (30) provided with magnets (61L, 61R) disposed along each of the first axis and the second axis, and the first member are opposed to each other. Due to the electromagnetic action of the second member (20) provided, the first element (52) and the second element (51, 552, 553) provided in each of the first member and the second member. A drive member (50) for relatively driving the first member and the second member, wherein one magnet reduces a rotational moment generated by electromagnetic coupling between the other magnet and the second element; A positioning device arranged in such a manner is described.

  In Patent Document 2, a rollable ball is sandwiched between a shift frame that holds a shake correction lens and a shift base, and the shift frame is pitched in a plane orthogonal to the optical axis by a moving coil type voice coil motor. And a magnet for detection fixed to the shift frame while urging the shift frame toward the base side by a magnetic attraction acting between the magnet and the yoke constituting the voice coil motor. And an image blur correction device including position detection means including a Hall element fixed to the shift base.

Japanese Patent No. 5181542 Japanese Patent No. 4006178

  In the positioning device described in Patent Document 1, since the arrangement of the magnetic poles of the position detection magnet and the drive magnet differs by 90 °, the position detection magnet and the drive magnet are particularly arranged in a compact configuration. The magnetic force of attraction and repulsion always occurs, and especially the attraction force between each magnet, when viewed from the drive magnet side, the magnetic field line of the drive magnet is pulled by the position detection magnet, so that part is effective for the coil As a result, the magnetic flux decreases, resulting in a decrease in thrust. When viewed from the position detection magnet side, there is a possibility of exacerbating the linear magnetic force change near the poles important for position detection due to the inflow of magnetic flux lines from the drive magnet or the outflow of magnetic flux from the position detection magnet. As a result, it may interfere with precision control and contribute to narrowing the control range. In addition, when the position detection magnet is close to the opposing yoke of the driving magnet, the position detection magnet is magnetically attracted to the opposing yoke for the driving magnet and becomes a load, which may cause a problem of inhibiting control. . Furthermore, since a ferrite magnet is used as the magnet, there is a problem that it is not possible to reduce the size and weight. In addition, since the image blur correction device described in Patent Document 2 is arranged so that the coil of the voice coil motor and the magnet for detection overlap when viewed from the optical axis direction, the position is affected by the magnetic field of the coil. There is a problem that the detection accuracy decreases.

  Accordingly, an object of the present invention is to provide a magnet device that can move a movable member linearly to a predetermined position with high accuracy and that can be reduced in size and weight.

The magnet device of the first invention is:
The fixed member includes a drive magnet installed via a back yoke, and a drive coil installed on a movable member installed to be movable in a predetermined direction with respect to the drive magnet. A voice coil motor with adjacent magnetic poles of different polarity along the direction of movement;
A holding member coupled to the fixed member at a predetermined interval so as to face the movable member;
A spherical body interposed between the holding member and the movable member and at a position facing the drive magnet;
A detection magnet that is installed on the movable member and has magnetic poles of different polarities adjacent to each other along the moving direction thereof, and a position detection member that has a magnetic field detection element that is installed on the holding member so as to face the detection magnet;
The holding member is provided with a first yoke into which a magnetic flux generated from the drive magnet flows and a second yoke into which a magnetic flux generated from the detection magnet flows.

  In the first invention, it is preferable that the projected area of the second yoke is set to a size that includes the position detecting magnet within a moving range of the movable member, as viewed from a plane.

The magnet device of the second invention is
A drive magnet installed on the base member and supported by a back yoke; and a drive coil installed on a movable member installed movably in a plane perpendicular to the central axis of the base member. A plurality of voice coil motors arranged around,
A spherical body that is interposed between a support member that is assembled to the base member at a predetermined interval and the base, and that is in a position facing the driving magnet in the axial direction;
Position detection having a plurality of detection magnets installed between the voice coil motors as viewed in the axial direction on the movable member, and a plurality of magnetic field detection elements installed on the support member facing the detection magnets. A member,
A first yoke supported by the base member and into which a magnetic flux generated from the driving magnet flows and a second yoke into which a magnetic flux generated from the detection magnet flows are provided. Is.

  In the second invention, it is preferable that the position detection magnet and the magnetic field detection element are arranged at positions that are point-symmetric with the drive coil in a plane viewed from the axial direction.

  In the present invention, it is preferable that the projected area of the second yoke is set to a size that includes the position detecting magnet within the moving range of the moving member as viewed from the axial direction.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to move a movable member to a predetermined position with high precision, the magnet apparatus which can be reduced in size and weight can be obtained.

It is a top view of the magnet apparatus concerning the 1st Embodiment of this invention. It is a top view which shows the positional relationship of VCM and a position detection member in the magnet apparatus shown in FIG. It is the sectional view on the AA line of FIG. It is a figure which shows typically the positional relationship of a 2nd yoke and a magnet for a detection. The position detection part in 1st Embodiment is shown, (a) is sectional drawing which shows a magnetic field detection element part typically, (b) is a figure which shows magnetic flux density distribution. It is a top view of the magnet apparatus concerning the 2nd Embodiment of this invention. It is a top view which shows the positional relationship of VCM and a position detection member in the magnet apparatus shown in FIG. It is the sectional view on the AA line of FIG. It is a figure which shows typically the positional relationship of the 2nd yoke and the magnet for a detection in 2nd Embodiment.

  The details of the present invention will be described with reference to the accompanying drawings.

<First Embodiment>
As shown in FIGS. 1 to 3, the magnet device 1 includes a rectangular holding member 4 coupled to a plurality of (for example, four) pillars 3 erected on a rectangular fixing member 2, and a fixing member 2. On the other hand, it has a spherical body 6 that supports a movable member 5 having an annular portion so as to be slidable in a predetermined direction (X-axis direction) within a plane orthogonal to the Z-axis (movable center). The magnet device 1 includes a movable coil type voice coil motor 9 (hereinafter referred to as “VCM 9”) and a movable member 5 for reciprocating the movable member 5 in the X-axis direction within a plane perpendicular to the Z-axis. A position detection member 14 for detecting the amount of movement is provided. Although the movable member 5 has an optical element (not shown), for example, it is not limited to this.

  The movable member 5 is arranged along the X-axis direction so as to sandwich a cylindrical portion that holds the outer peripheral edge of an optical element (not shown), and is formed on one end side to accommodate a spherical body 6. And a rectangular member having a detection magnet 16 installed on the other end side. The circular hole portion is formed in a size that allows the spherical body 6 to roll within a predetermined range. A flexible printed circuit board (referred to as “first FPC”) on which the movable coil 13, which is a flat air-core coil, constituting the VCM 9 is mounted on the back side (the side facing the fixed member) of the circular hole portion. 12 is fixed.

  The holding member 4 has a first yoke 8A made of a ferromagnetic material (for example, a steel material such as SS material) on one end side, and is made of a ferromagnetic material (for example, a steel material such as SS material) on the other end side. A second yoke 8B and a flexible printed circuit board (hereinafter referred to as “second FPC”) 7 are provided. A wiring pattern (not shown) is formed on one surface (surface on the movable member side) of the second FPC 7 and a magnetic field detection element (Hall element in this example) 15 is mounted.

  The fixing member 2 is a rectangular member in which pillars 3 (shown by broken lines in FIG. 1) are erected at each corner portion. A rectangular magnet holding step portion is formed on the fixing member 2, and a rectangular drive magnet 11 constituting the VCM 9 is fixed to the step portion via a back yoke 10. The fixed member 2, the movable member 5, and the support column 3 are formed of a non-magnetic material (for example, engineering plastic).

  Since the first yoke 8A is provided at a position where the magnetic flux generated from the fixed magnet flows, the thrust generated by the VCM 9 is improved. The first suction yoke 8A is a rectangular member made of a ferromagnetic material (steel material such as SS material), and is longer than the length of the effective winding portion of the movable coil 13 (the length of the straight portion in the Y direction). It is set to a large size. The second yoke 8B is a rectangular member made of a ferromagnetic material (an iron and steel material such as an SS material), and is provided at a position where a magnetic flux flowing out from the detection magnet flows. Therefore, the movable member 5 is magnetically attracted in the direction away from the fixed member 2 along the axial direction. The second yoke 8B is set to a size that does not protrude from the fixing member 2 and overlaps the detection magnet 16. The thicknesses of these yokes may be set according to the magnetic characteristics of the magnet, but can be set in the range of 0.5 to 1.5 mm, for example. Further, as shown in FIG. 4, the projected area of the second yoke 8B is detected within the moving range of the movable member 5 (region surrounded by the alternate long and short dash line B) when viewed from the plane (direction perpendicular to the paper surface). The size is set so that the magnet 16 does not protrude. That is, the width Lr of the second yoke 8B is set to have a width (Lr> Ls) that is equal to or greater than the width Ls of the movable range B of the detection magnet 16.

  The holding member 4 has a circular hole on the side facing the movable member 5 in order to hold the spherical body 6 so as to be movable within a predetermined range between the holding member 4 and the movable member 2. As shown in FIG. 3, since a plurality of spherical bodies are interposed between the movable member 5 and the support member 4 when viewed from the axial direction, the movable member 5 has a plane perpendicular to the Z axis (X direction and It is supported in such a manner that it can move in the X direction on the surface including the Y direction perpendicular to it, and the sliding (friction) resistance is reduced, so that accurate positional accuracy can be ensured.

  The magnetic field detection element 15 is mounted on the second FPC 7 so that the center thereof is in the middle of the detection magnet 16. Since this magnetic field detection element (for example, Hall element) 15 exists at a position far away from the movable coil 13, it is not affected by magnetic flux generated from the movable coil (without noise), and highly accurate position detection is possible. It becomes possible.

The VCM 9 which is a driving means for the movable member 5 is fixed to the fixed member 2 and the movable coil 13 which is an oblong flat air-core coil installed in the movable member 5 in order to reduce the weight of the movable member. Drive magnet 11 (see FIG. 3). Each of the fixed drive magnets 11 is magnetized in the thickness direction (Z-axis direction) and magnetized so that magnetic poles of different polarities are adjacent to each other in the longitudinal direction (X direction). It is installed on the surface of a flat back yoke 10 made of a steel material. The drive magnet 11 can be formed of a known permanent magnet, but is preferably formed of a rare earth sintered magnet in order to obtain high thrust with low power consumption, for example, 358 to 437 kJ / m ³ [45 to 55 MGOe. And a residual magnetic flux density of 1.3 T or more.

  When the movable member is driven by the VCM, a position detection member 14 for detecting the movement amount of the movable member 5 is provided in order to perform feedback control based on the movement amount of the movable member 2. The position detection member 14 includes a detection magnet 16 fixed to the movable member 5 and a magnetic field detection element 15 for detecting a magnetic field generated from each magnet. Although not shown, if necessary, a flat back yoke made of a ferromagnetic material (for example, a steel material such as SS material) is installed on the back surface of the detection magnet (on the opposite side to the surface facing the magnetic field detection element). Can do. Further, a second yoke 8B is provided on the surface of the second FPC 7 (the surface on which the magnetic field detection element is not mounted), and a magnetic flux generated from the detection magnet flows into the second FPC 7 so that the detection magnet and the second FPC 7 are in contact with each other. A magnetic attractive force is generated between the movable member 2 and the yoke, and the movable member 2 is attracted to the support member 4 side (see FIG. 3). That is, the second yoke forms a magnetic circuit with the detection magnet 16 and also has a function as a suction yoke that attracts the movable member 2 toward the holding member 4. Since the magnetic field detection element 15 is arranged at a position (point-symmetrical position) whose center is inverted with respect to the central axis Z with respect to the initial position (Z axis), the magnetic field detection element 15 is made to coincide with the thrust center. The same calculation as in the case of arrangement can be performed, and the amount of movement of the movable member 2 can be accurately detected.

  In the present embodiment, a pair of flat permanent magnets magnetized in the thickness direction (single-pole magnetized) are used as the detection magnet 16, but instead of the pair of flat permanent magnets. It is possible to use a single flat permanent magnet that is magnetized in the thickness direction and has adjacent magnetic poles of different polarities. Further, the movement amount of the movable member 2 can also be detected by mounting the magnetic field element 15 on the side opposite to the side facing the holding member 4 of the first FPC 7. In this case, the second yoke 8B has a shape provided with a hole that can prevent interference with the magnetic field detection element 15.

  As the detection magnet, a known permanent magnet can be used. However, since it is installed on the movable member, in order to reduce the weight, permanent magnet powder (the surface may be coated with resin) and the rare earth It is preferable to use a rare earth bonded magnet in which magnet powder is bonded with a polymer material such as resin or rubber.

  As shown in FIG. 5, the magnetic field detecting element 15 is centered at the initial position so as to coincide with the middle of the pair of detecting magnets 16 fixed to the movable member 2 (position where the magnetic pole is reversed: magnetic flux density = 0). Placed in. Therefore, on the surface of the magnetic field detection element 15, the magnetic flux density from one end to the other end of the detection magnet 16 is within a predetermined length L1 (L2) with a predetermined length sandwiching the middle (zero cross point) of the detection magnet. Since the magnetic flux density changes linearly, the position of the movable member 2 can be detected by detecting the output voltage of the magnetic field detection element. Since the magnetic field detection element 15 outputs a voltage proportional to the magnetic flux density, if the size of the magnet part and the distance between the magnetic field detection element and the magnet part are set appropriately, the magnetic field detection element 15 is proportional to the amount of movement (magnetic force change) of the detection magnet. Since the output voltage can be output to the control circuit and the linearity of the output voltage can be improved, highly accurate position detection can be performed.

  In the first embodiment, as described above, the second yoke 8B, the magnetic field detection element 15, and the detection magnet 16 are arranged in this order along the Z-axis direction. Thus, since the magnetic field detection element 15 is not opposed to the movable coil 13 and is disposed at a position away from the movable coil, the magnetic flux generated from the movable coil does not affect the magnetic field detection element. Further, since the second yoke 8B facing the detection magnet 16 is disposed at a position where the magnetic flux generated from the detection magnet 16 flows into the second yoke 8B, the movable member 2 faces the second yoke 8B. Magnetically attracted. By setting the magnetic attractive force F to an appropriate value according to the mass of the movable member, the movable member 2 can be smoothly supported in a plane orthogonal to the Z axis. The value of the magnetic attractive force F is preferably about twice the mass of the movable member. For example, when the mass of the movable member is about 25-30 g, it is preferably in the range of 50-60 gf.

  In the first embodiment, since the positions of the first yoke 8A and the second yoke 8B in the axial direction (Z-axis direction) can be adjusted independently, high thrust can be obtained and magnetism by the detection magnet can be obtained. The suction force can be adjusted to an optimum value. For example, when it is necessary to increase the thrust of the VCM 9, the distance ga (see FIG. 3) between the first yoke 8A and the drive magnet 11 may be reduced. If it is necessary to reduce the magnetic attractive force between the second yoke 8B and the detection magnet 16, the distance gb between them (see FIG. 3) may be increased. In other words, by dividing the yoke into the first and second, it becomes possible to maximize the thrust of the VCM and obtain the optimum magnetic attractive force, and to satisfy both the thrust and attractive force requirements. Become. Further, by arranging the two yokes to have the same shape (for example, in a rectangular shape), they can be manufactured with the same mold, and the cost can be reduced.

  The operation of the magnet device 1 will be described. When the movable coil 13 of the VCM 9 is energized, the drive magnet 11 facing the coil is fixed to the base member 2, so that a thrust along the X-axis direction is generated in the movable coil 13 based on Fleming's left-hand rule. . That is, the movable member 2 can move linearly on a plane perpendicular to the axial direction. Therefore, the magnitude and direction of the thrust can be adjusted by changing the polarity and / or magnitude of the current supplied to the movable coil 13. This drive amount can be fed back to the control circuit to move the movable member to the target position (servo control).

  When the movable member is driven by VCM and a Hall element is used as the magnetic field detection element, the maximum moving distance of the movable member can be set within a range of ± (0.5 to 1.0) mm from the initial position, for example. it can. In this movement range, it is preferable that the difference between the actual movement amount and the movement amount corresponding to the output voltage of the magnetic field detection element (the error amount with respect to the theoretical straight line) is small (high linearity). The error amount with respect to the theoretical straight line can be kept within 0.04 mm.

<Second Embodiment>
In the following description, the same functional parts as those in the first embodiment are denoted by the same reference numerals.

  As shown in FIGS. 6 to 8, the magnet device 1 has a disk-shaped support member 4 coupled to a plurality of (for example, three) columns 3 erected on the fixing member 2, and the fixing member 2. It has a plurality of (for example, three) spherical bodies 6 that slidably support an annular movable member 5 in a plane orthogonal to the central axis (Z axis). The magnet device 1 includes a movable coil type VCM 9 and a position detection member 14 that detects the amount of movement of the movable member 5 in order to drive the movable member 5 in a plane perpendicular to the central axis. Although the movable member 5 has an optical element (not shown), it is not limited to this.

  The movable member 5 is a ring-shaped member having a circular hole portion for accommodating a steel ball and a detection magnet 16 formed on the outer peripheral side of a cylindrical portion that holds the outer peripheral edge of an optical element (not shown). is there. Each of the circular hole portion and the detection magnet 16 is configured such that the detection magnet 13 and the circular hole portion are alternately arranged along the circumferential direction at equal angular intervals (120 °) when viewed from the central axis direction. Yes. Each circular hole is formed in a size that allows the steel ball 6 to roll within a predetermined range. Further, the first FPC 12 on which the movable coil 13, which is a flat air-core coil, constituting the VCM 9 is fixed to the back side (the side facing the fixed member) of each circular hole portion.

  The fixed side member has a first yoke 8A and a second yoke 8B made of a ferromagnetic material and an annular second FPC 7 fixed to a holding member 4 coupled to the fixed member 2. A wiring pattern (not shown) is formed on one surface (surface on the movable member side) of the second FPC 7 and a magnetic field detection element (for example, a Hall element) 15 is mounted.

  The fixing member 2 is an annular member in which columns 3 (shown by broken lines in FIG. 6) are erected at predetermined intervals along the circumferential direction. The fixing member 2 is formed with rectangular magnet holding step portions at equal angular intervals (120 °) along the circumferential direction, and rectangular drive magnets 11 constituting the VCM 9 are backed on each step portion. It is fixed via the yoke 10. The fixed member 2, the movable member 5, and the support column 3 are formed of a non-magnetic material (for example, engineering plastic).

  The first yoke 8A is made of a ferromagnetic material (steel material such as an SS material) and is provided so that a magnetic flux generated from the drive magnet flows. Since the second yoke 8B is made of a ferromagnetic material (steel material such as SS material) and is provided at a position where the magnetic flux flowing out from the detection magnet flows, the movable member 2 moves from the fixed member 2 along the axial direction. It is magnetically attracted away. The yoke 8 has an outer diameter D1 that is smaller than the outer diameter of the base member 2 and an inner diameter D2 that is set to a dimension that overlaps the detection magnet 16 on the inner diameter side. Further, the thickness t is set in a range of 0.5 to 1.5 mm, for example. Further, as shown in FIG. 9, the projected area of the second yoke 8B protrudes from the detection magnet 16 within the moving range of the movable member 2 (region surrounded by the one-dot chain line B) as seen from the optical axis direction. It is set so that there is no size. That is, the width Lr (D1-D2 / 2) of the yoke 8B is set to have a width (Lr> Ls) that is equal to or greater than the width Ls of the movable range B of the detection magnet 16.

  The holding member 4 has a circular hole on the side facing the movable member 2 in order to support the spherical body 6 with the movable member 2. As shown in FIG. 8, since a plurality of spherical bodies are interposed between the movable member 5 and the holding member 4 when viewed from the Z-axis direction, the movable member 5 has a plane perpendicular to the Z-axis (X direction). And a plane including the Y direction perpendicular to the same), the sliding (friction) resistance is reduced, and accurate positional accuracy can be ensured.

  The younger brother 1FPC 7 has a thrust at which the centers of the magnetic field detecting elements 15 arranged at equal angular intervals along the circumferential direction are located in the middle of the movable coils 13 (coincident with the middle of the drive magnet) along the circumferential direction. It arrange | positions so that it may be in the position reversed with respect to the center (refer FIG. 3). When the center of the magnetic field detection element is at a position reversed from the center of thrust, the current position can be easily calculated, and the movable member can be quickly moved to the target position. In addition, since the magnetic field detection element 15 is present at a position far away from the movable coil 13, it is not affected by the magnetic flux generated from the coil (without noise) and can detect the position with high accuracy.

  The VCM 9 that drives the movable member 5 is fixed to the fixed member 2 and the movable coil 13 that is an oblong flat air-core coil installed on the movable member 5 in order to reduce the weight of the movable member. It has the drive magnet 11 (refer FIG. 8). Each of the drive magnets 11 is magnetized in the thickness direction (axial direction) and magnetized so that magnetic poles of different polarities are adjacent to each other along the longitudinal direction (radial direction of the fixed member). It is installed on the surface of a flat back yoke 10 made of a steel material. The drive magnet 11 can be formed of a known permanent magnet, but is preferably formed of a rare earth sintered magnet as in the first embodiment in order to obtain high thrust with low power consumption.

  When the movable member is driven by the VCM, a position detection member 14 for detecting the movement amount of the movable member 5 is provided in order to perform feedback control based on the movement amount of the movable member 5. The position detection member 14 includes a detection magnet 16 fixed to the movable member 5 and a magnetic field detection element 15 for detecting a magnetic field generated from each magnet. Although not shown, if necessary, a flat back yoke made of a ferromagnetic material (for example, a steel material such as SS material) is installed on the back surface of the detection magnet (on the opposite side to the surface facing the magnetic field detection element). Can do. Further, a second yoke 8B is provided on the surface of the first FPC 7 (the surface on which the magnetic field detection element is not mounted), and a magnetic flux generated from the detection magnet flows into the first FPC 7 so that the detection magnet, the yoke, During this time, a magnetic attractive force is generated, and the movable member 2 is attracted to the holding member 4 side (see FIG. 8). That is, the second yoke forms a magnetic circuit with the detection magnet 16 and also has a function as a suction yoke that attracts the movable member 2 to the pointing member 4 side. Since the magnetic field detection element 15 is arranged at a position (point symmetrical position) whose center is reversed with respect to the Z axis (thrust center), it is the same as the case where the magnetic field detection element is arranged so as to coincide with the thrust center. Calculations can be performed, and the amount of movement of the movable member 5 can be accurately detected.

  The detection magnet 16 is a pair of flat permanent magnets magnetized in the thickness direction (single-pole magnetized), but magnetized in the thickness direction instead of the pair of flat permanent magnets. In addition, a single flat permanent magnet having adjacent magnetic poles of different polarities can be used. The magnetic field detection element 15 can also detect the amount of movement of the movable member 5 by mounting it on the opposite side of the first FPC 7 from the side facing the support member 4. The second yoke 8B has a shape that can prevent interference with the magnetic field detection element 15.

  As the detection magnet, a known permanent magnet can be used as in the first embodiment. However, since it is installed on a movable member, permanent magnet powder (surface is made of resin) to reduce the weight. And a rare earth bonded magnet in which the rare earth magnet powder is bonded with a polymer material such as resin or rubber. However, since the output voltage of the Hall element decreases, it may be amplified electrically. As the position detecting magnet, it is preferable to use a rare earth bonded magnet having a surface magnetic flux density of 0.1 to 0.2T. The material of the detection magnet is preferably a bonded magnet in order to reduce the mass of the movable part. However, if the mass of the movable member is large, even a small rare-earth sintered magnet can substantially reduce the weight of the movable part. There is no practical problem because it does not interfere.

  In the initial position where the movable member 2 (moving in the S1 direction or the S2 direction) is centered, the magnetic field detection element 15 is intermediate between the pair of detection magnets 16 whose centers are fixed to the movable member 2 (the magnetic poles are reversed). Position: magnetic flux density = 0). Therefore, on the surface of the magnetic field detection element 15, the magnetic flux density linearly changes in a range of a predetermined length across the middle (zero cross point) of the detection magnet from one end of the detection magnet 16 to the other end. . Since the magnetic field detection element outputs a voltage proportional to the magnetic flux density, if the size of the magnet part and the distance between the hall element and the magnet part are set appropriately, the voltage proportional to the amount of movement (magnetic force change) of the detection magnet Can be output to the control circuit, and the linearity of the output voltage can be improved, so that highly accurate positioning can be performed.

  In the second embodiment, as described above, the second yoke 8B, the magnetic field detection element 15, and the detection magnet 16 are arranged in this order along the central axis direction, and the magnetic field detection element is sandwiched between the central axes. The first yoke 8 </ b> A, the spherical body 6, the movable coil 13, and the drive magnet 11 are arranged in this order at a point symmetric with respect to 16. Thus, since the magnetic field detection element 15 is not opposed to the movable coil 13 and is disposed at a position away from the movable coil, the magnetic flux generated from the movable coil does not affect the magnetic field detection element. Further, since the second yoke 8B facing the detection magnet 16 is disposed at a position where the magnetic flux generated from the detection magnet 16 flows into the second yoke 8B, the movable member 2 is magnetically directed toward the yoke 8B. Sucked into. By setting the magnetic attraction force F to an appropriate value corresponding to the mass of the movable member, the movable member 2 can be smoothly supported in a plane orthogonal to the central axis. The value of the magnetic attractive force F is preferably about twice the mass of the movable member. For example, when the mass of the movable member is about 25-30 g, it is preferably in the range of 50-60 gf.

  Furthermore, the spherical body 6 for supporting the movable member 5 movably on a plane perpendicular to the central axis is disposed between the fixed magnet 11 supported by the back yoke 10 and the first yoke 8A. The magnetic flux generated from the fixed magnet 11 can be applied to the ball of the movable member 5 even when the magnet device is assembled, for example, if the spherical body 6 is a magnetic steel ball, a magnetic attractive force acts on the steel ball. It can be held at the center position of the receiving part.

  The magnet device of the present invention is configured so that, for example, the mass of the movable member 5 is 20 to 30 g, and the thrust mass ratio (maximum thrust / the mass of the movable member) is in the range of 2.0 to 3.0. be able to.

  In the magnet device 1, the magnitude and direction of the thrust can be adjusted by changing the polarity and / or magnitude of the current supplied to each movable coil, so that the movable force can be obtained by synthesizing the thrust generated in each VCM. The member 5 can be driven in an arbitrary direction within a plane perpendicular to the central axis. This drive amount is fed back to the control circuit, and servo control for moving the movable member to the target position can be performed.

  When the movable member is driven by VCM and a Hall element is used as the position detection element, the maximum moving distance of the movable member can be set within a range of ± (0.5 to 1.0) mm from the initial position, for example. it can. In this movement range, the difference between the actual movement amount and the movement amount corresponding to the output voltage of the magnetic field detection element (error amount with respect to the theoretical straight line) must be small (high linearity). Thus, the error amount with respect to the theoretical line can be within 0.04 mm.

  In the second embodiment, as in the first embodiment, since the positions in the axial direction (Z-axis direction) of the first yoke 8A and the second yoke 8B can be adjusted independently, high thrust is achieved. While being obtained, the magnetic attraction force by the detection magnet can be adjusted to an optimum value regardless of the thrust force.

  According to the first and second embodiments, (1) since the magnetic circuit is formed by arranging the fixed magnet, the movable coil, and the attraction yoke along the axial direction, without increasing the power consumption, Fixed magnets with large magnetic characteristics can be used, and the thrust mass ratio can be increased. (2) Since a detection magnet is used separately from the fixed magnet, priority is given to the straightness of the output voltage of the magnetic field detection element. In addition to being able to set the size of the detection magnet, it is possible to arrange the magnetic field detection element at a position where the magnetic flux generated from the movable coil does not reach, and to eliminate the influence of the movable coil on the magnetic field detection element In particular, the following effects can be obtained.

(3) Since two other yokes are provided on the fixed side member at positions facing the drive magnet and the detection magnet, the thrust generated by the VCM for driving the movable member and the movable member for attracting the movable member to the fixed side member The magnetic attractive force can be adjusted independently (to an optimum value).

1: Magnet device,
2: fixing member,
3: Support,
4: Holding member,
5: movable member,
6: Steel ball,
7: Second FPC,
8A: first suction yoke,
8B: second suction yoke,
9: VCM,
10: Back yoke,
11: Driving magnet,
12: First FPC,
13: Moving coil,
14: position detection member,
15: Magnetic field detection element,
16: detection magnet,
B: movement range, F: magnetic attraction force, Lr: width of attraction yoke, Ls: movement length,
ga: Distance between the drive magnet and the first yoke gb: Distance between the magnetic field detection element and the second yoke C: Zero cross point, L1, L2: Linear magnetic flux density distribution region

Claims (5)

The fixed member includes a drive magnet installed via a back yoke, and a drive coil installed on a movable member installed to be movable in a predetermined direction with respect to the drive magnet. A voice coil motor with adjacent magnetic poles of different polarity along the direction of movement;
A holding member coupled to the fixed member at a predetermined interval so as to face the movable member;
A spherical body interposed between the holding member and the movable member and at a position facing the drive magnet;
A detection magnet that is installed on the movable member and has magnetic poles of different polarities adjacent to each other along the moving direction thereof, and a position detection member that has a magnetic field detection element that is installed on the holding member so as to face the detection magnet;
A magnet apparatus comprising: a first yoke that is installed on the holding member and into which a magnetic flux generated from the drive magnet flows; and a second yoke into which a magnetic flux generated from the detection magnet flows.   2. The magnet device according to claim 1, wherein the projected area of the second yoke is set to a size that includes the position detection magnet within a moving range of the movable member when viewed from a plane. A drive magnet installed on a disk-shaped base member and supported by a back yoke; and a drive coil installed on a movable member installed movably in a plane perpendicular to the central axis of the base member; A plurality of voice coil motors arranged around the central axis;
A plurality of spherical bodies that are interposed between the base member and an intermediate member that is assembled to the base member at a predetermined interval in the axial direction, and that are in positions facing the driving magnet in the axial direction;
Position detection having a plurality of detection magnets installed between the voice coil motors as viewed in the axial direction on the movable member, and a plurality of magnetic field detection elements installed on the intermediate member facing the detection magnets. Members,
A magnet apparatus comprising: a first yoke installed on the intermediate member, into which a magnetic flux generated from the drive magnet flows; and a second yoke into which a magnetic flux generated from the detection magnet flows.   2. The magnet device according to claim 1, wherein the position detection magnet and the magnetic field detection element are arranged at a position that is point-symmetric with the drive coil in a plane viewed from an axial direction.   3. The magnet according to claim 1, wherein the projected area of the second yoke is set to a size that includes the position detection magnet within a moving range of the moving member when viewed from the axial direction. apparatus.

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