JP2011242680A - Camera shake correction unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a camera shake correction unit which is provided with a moving magnetic type voice coil motor and is capable of smoothly switching between a locking operation and an unlocking operation.SOLUTION: A cameral shake correction unit comprises: a fixing member; a moving member to support a correction lens; support means to support the moving member in a manner that makes the same movable in a plane orthogonal to an optical axis; a plurality of voice coil motors for correction to move the moving member in the plane orthogonal to the optical axis; a locking member provided with locking pins to lock the moving member; and a moving magnet type voice coil motor for locking to drive the locking member. The moving magnet type voice coil motor for locking includes: air core coils fixed to the fixing member; attraction yokes on air core portions of the air core coils; moving magnets on the locking member; and regulating members composed of ferromagnetic materials arranged at both ends in a movable range of the moving magnets.

Description

  The present invention relates to a camera shake correction unit including a movable magnet type driving unit that moves a camera shake correction lens in order to prevent image shake caused by a shake applied to an optical apparatus.

  In imaging optical devices such as digital cameras, camera bodies and interchangeable lenses are generally equipped with an anti-shake mechanism in order to take high-quality photos as the taking lens becomes longer in focus and has a higher magnification zoom. It has become.

  Analyzing camera shake in photography, the direction perpendicular to the optical axis due to arm tremor (frequency around 10 Hz) and body shake (frequency around several Hz), shutter impact and hand shake during release ( Vertical and horizontal) and pitch, yaw and roll rotation. In particular, it is important to compensate for pitch and yaw rotational shake that greatly affects the image to be formed.

  As a system for preventing this camera shake, a sensor shift system for driving an image sensor (CCD, CMOS, etc.) and a lens shift system for driving a photographing optical system are generally used. The sensor shift method that corrects camera shake by moving the imaging position by driving the image sensor can use an existing lens and can correct camera shake with high accuracy. The lens shift system that moves the imaging position by driving a part of the imaging lens in a direction perpendicular to the optical axis can be optimized for each lens, preventing camera shake on the viewfinder while observing the subject. There is an advantage that the function can be visually recognized.

  Patent Document 1 (Patent No. 4133990) discloses a movable part such as a correction lens by arranging a drive magnet so that a magnetic neutral line is directed in a substantially radial direction around the optical axis of the correction lens. Disclosed is a camera shake correction device having an actuator that can be moved not only in translation but also in rotation, for locking the moving frame with respect to the fixed plate when the moving frame is not controlled. A manual locking member is disclosed. However, since the locking mechanism described in Patent Document 1 switches between locking and releasing the moving frame by manual operation, the operability is poor and improvement is desired.

  Patent Document 2 (Japanese Patent No. 4336698) is an actuator for translating an imaging lens within a plane orthogonal to its optical axis to prevent image blur, and a fixed portion and the imaging lens are attached to the actuator. Movable part, movable part support means for supporting the movable part so that the movable part can be moved on a plane parallel to the fixed part, and drive means for moving the movable part relative to the fixed part A locking member movably provided between the first position and the second position, and a biasing member for biasing the locking member so that the locking member is moved to the second position. A biasing means; a holding means for holding the locking member in the first position against the biasing force of the biasing means; and the movable part acting on the holding means when moved to a predetermined release position. And holding release means for releasing the holding of the locking member; When the locking member is moved to the second position by the urging force of the urging means, a movable portion urging means for moving the movable portion to a predetermined locking position along with the movement, and the movable portion Discloses an actuator having an engagement receiving portion that engages with the movable portion to lock the movable portion when moved to the locking position. Patent Document 2 describes that with such a configuration, the movable portion can be locked without providing an actuator for driving a member such as a lock ring.

  However, in the camera shake prevention device described in Patent Document 2, an actuator for driving the lock ring can be omitted, but in addition to the lock lever and the lock ring (locking rotation plate), a forced rotation plate is used. A biasing means such as a spring is required, and these lock levers and lock rings have a complicated shape.

  Patent Document 3 (Japanese Patent Laid-Open No. 2009-116033) holds an optical component that performs image blur correction, a movable holding member, a lock member that locks the holding member when the image blur correction is not in operation, and A conductive contact terminal that biases the position detection pattern provided on the lock member and slides on the position detection pattern as the lock member moves, and is electrically connected to the contact terminal. And a detection circuit that detects a relative position of the lock member with respect to the holding member based on a relative position of the contact terminal with respect to the position detection pattern.

  However, since the actuator described in Patent Document 3 includes a rotating coil that constitutes a part of a voice coil motor for rotating the locking member, the terminal of the coil (start and end) is provided. ) Is complicated and coil breakage is likely to occur.

Japanese Patent No. 4133990 Japanese Patent No. 4336698 JP 2009-116033

  Accordingly, an object of the present invention is to provide a camera shake correction unit that includes a movable magnet type voice coil motor for driving a locking member and that can be smoothly switched between lock and unlock.

  As a result of diligent research in view of the above object, the inventors of the present invention constituted a movable magnet type voice coil motor with an air-core coil provided on the fixed member and a permanent magnet provided on the locking member, and the movable range was By providing a restricting member made of a ferromagnetic material at both ends of the coil, the inventors have found that there is no problem of coil disconnection and the like, and that the movable member can be locked and unlocked smoothly and reliably. .

That is, the image stabilization unit of the present invention is
A fixing member made of a non-magnetic material fixed in the lens barrel;
A ring-shaped movable member arranged to face the fixed member as viewed from the optical axis direction and supporting the correction lens;
Support means for supporting the movable member movably in a plane perpendicular to the optical axis of the correction lens;
A plurality of correcting voice coil motors that move the movable member in a plane perpendicular to the optical axis;
Control means for controlling the moving direction and moving amount of the correcting voice coil motor;
A locking member provided with a locking pin for locking the movable member;
A camera shake correction unit including a locking movable magnet type voice coil motor for driving the locking member;
The locking movable magnet type voice coil motor includes an air core coil provided on the fixed member, a suction yoke provided on an air core portion of the air core coil, and a magnetic generation provided on the locking member. And a restricting member made of a ferromagnetic material provided at both ends of the movable range of the magnetism generating means.

  The movable member has a locking groove for receiving the locking pin when the locking member is rotated and locking the movable member, and the locking groove is in a moving direction of the locking pin. It is preferable to have a shape in which the back side is wider than the entrance side.

  The locking voice coil motor preferably includes a magnetic shield member provided on the fixed member over a movable range of the magnetism generating means.

  The magnetic field generating means includes a pair of rectangular parallelepiped Nd-Fe-B anisotropic sintered magnets that are compression molded in a magnetic field perpendicular to the molding direction and magnetized in the same direction as the molding direction. The sintered magnet is preferably arranged in a substantially fan shape so that magnetic poles of different polarities are adjacent to each other when viewed from the optical axis direction.

The correcting voice coil motor includes a plurality of oblong flat air core coils provided on the fixed member, and a plurality of magnets provided on the movable member at positions corresponding to the air core coils. Composed of circuit parts,
The air-core coil has a longitudinal direction that coincides with a tangential direction at an angular interval of 90 to 120 ° on a circumference centered on the optical axis in a plane orthogonal to the optical axis direction of the fixing member. Arranged as
The magnetic circuit section is fixed so that a flat plate-shaped yoke made of a ferromagnetic material fixed to the movable member and a pair of magnetic poles of different polarity are opposed to the air-core coils. Including a plurality of flat permanent magnets,
The permanent magnet is preferably installed such that a pair of magnetic poles having different polarities face the optical axis in a plane orthogonal to the optical axis direction.

  According to the present invention, since the voice coil motor for locking the correction lens is configured as a movable magnet type, disconnection is prevented, and the switching between the locking operation and the unlocking operation can be performed smoothly.

It is the schematic which shows the structure of the digital camera carrying the camera-shake correction unit of this invention. It is a disassembled perspective view which shows the camera-shake correction unit of this invention. It is the disassembled perspective view which looked at FIG. 2 from the A direction. FIG. 3 is a sectional view taken along line BB in FIG. 2. It is the perspective view which showed the movable frame of the camera-shake correction unit of FIG. 2, and was seen from the (a) C direction and (b) the back side. It is the perspective view which looked at the fixed frame A of the camera-shake correction unit of FIG. 2 from the (a) C direction and (b) the back side. It is the perspective view which looked at the fixed frame B of the camera-shake correction unit of FIG. 2 as seen from (a) C direction and (b) the back side. It is the perspective view which looked at the latching movable frame of the camera-shake correction unit of FIG. 2 from the (a) C direction and (b) the back side. It is a schematic diagram which shows the thrust generation mechanism of the voice coil motor for correction | amendment. FIG. 10 is a sectional view taken along the line DD in FIG. 9. It is (a) top view and (b) GG sectional drawing which show a locking part typically. It is sectional drawing which shows an example of the voice coil motor for latching typically. FIG. 12 is viewed from the H direction, (a) a front view showing the positional relationship between the pair of locking magnets, (b) a front view showing the positional relationship between the locking magnet, the locking coil, and the wiring board; c) A front view showing a positional relationship among a locking back yoke, a locking magnet, a locking suction yoke, and a magnetic shield plate. It is a graph which shows the magnetic flux density of the optical axis direction detected with a Hall element when a magnetic circuit part is moved to radial direction. It is a block diagram which shows the control circuit of the camera-shake correction unit of this invention. It is a block diagram which shows the position detection circuit of a correction lens.

<Embodiment 1>
[1] Digital Camera FIG. 1 shows an example of a digital single-lens reflex camera (hereinafter simply referred to as “camera”) provided with the image stabilization unit of the present invention. The camera 100 includes a body 110 and a lens barrel 114. The body 110 detects an optical image of a subject imaged by the lens barrel 114 via a solid-state image pickup such as a CCD. The lens barrel 114 includes a plurality of lens groups (a first lens group 115a, a second lens group 115b, an alternating combination of a negative lens group and a positive lens group) in order to obtain an aberration correction effect. A third lens group 115c and a fourth lens group 115d), and a diaphragm (not shown). The camera shake correction unit 10 of the present invention is provided in the third lens group 115c of the lens barrel 114.

  Since the camera shake correction unit 10 of the present invention employs a lens shift method as a camera shake correction unit, the camera shake prevention function can be viewed even while observing a subject on the viewfinder. In this lens shift method, the optical axis is corrected by displacing the camera shake correction lens group in the direction orthogonal to the optical axis, so it is important to be able to correct the camera shake of the photographer with the smallest possible lens shift amount. Therefore, a lens group that satisfies these conditions may be selected as the correction lens group, and in the present embodiment, the third lens group 115c is shown as a camera shake correction lens group (hereinafter referred to as “correction lens 11”). ing.

  In camera shake correction, the camera shake amount (angular acceleration) detected by the camera shake amount detection unit 5 provided in the body 110 is input to the control circuit 6, and a drive current corresponding to the camera shake amount is supplied to the drive circuit 7. Then, the position of the correction lens 11 is controlled so that an image with little camera shake is obtained by shifting the incident optical axis. The shake amount detection unit 5 includes a detector that can detect a vertical shake amount and a horizontal shake amount, for example, two gyro sensors. In the camera shake correction unit 10, in order to prevent the correction optical system from tilting (tilting) with respect to the optical axis, the surface of the camera shake correction unit drive unit (correction voice coil motor) passes through the center of the correction optical system and is perpendicular to the optical axis. It is preferable to put in.

[2] Image stabilization unit
(1) Overall Configuration FIGS. 2 to 4 show an example of a camera shake correction unit. The camera shake correction unit 10 includes a movable member 1 having a correction lens 11, a fixed member 2 for holding the movable member 1 in a lens barrel 120 (see FIG. 1), and the movable member 1 perpendicular to the optical axis. Movable magnet type correction voice coil motor (hereinafter simply referred to as “correction VCM”) 3 that is driven in a smooth plane, and a locking mechanism section that keeps the correction lens 11 stationary at a position that coincides with the optical axis during non-imaging. 4 and.

(2) Movable member and fixed member The movable member 1 includes a correction lens 11 and a ring-shaped movable frame 12 made of a nonmagnetic material that holds the outer peripheral edge of the correction lens 11 and has a flange 121 (see FIG. 5). ). As shown in FIG. 6, the fixing member 2 includes a ring-shaped fixing frame A 21 made of a nonmagnetic material that receives a part of the movable frame 12 and has a flange portion 210, and a wiring board 22. The wiring board is preferably a flexible wiring board (FPC). The movable member 1 is supported by a ring-shaped fixing member 2 made of a non-magnetic material in a state where it can move in any direction on a plane (XY plane) perpendicular to the optical axis direction (Z-axis direction). . The movable member 1 and the fixed member 2 are preferably supported by a support means including a plurality of rolling elements 13 interposed between them, for example. By supporting by such a method, the sliding (friction) resistance between the movable member 1 and the fixed member 2 is reduced, and it is possible to accurately correct minute camera shake.

(a) Movable Frame As shown in FIG. 5 (b), the movable frame 12 includes a ring portion 120 and a flange portion 121 that support the correction lens 11. In the flange portion 121, magnetic circuit holding portions 123a, 123b, 123c are formed at equal angular intervals (120 °) along the circumferential direction, and between the magnetic circuit holding portions 123a, 123b, 123c, Second accommodating portions 122a, 122b, 122c into which a part of the steel balls can be inserted are formed. As shown in FIG. 5 (a), on the surface of the flange 121 opposite to the surface facing the fixed frame A21, a disk-like shape is provided at a position corresponding to the second accommodating portions 122a, 122b, 122c. Holding holes 124a, 124b, 124c for holding the back yokes 126a, 126b, 126c and the second attracting magnets 125a, 125b, 125c are formed. Further, on the opposite side of the magnetic circuit holding portions 123a, 123b, 123c, a latching portion having a latching groove 128a, 128b, 128c for receiving a latching pin described later and locking the movable frame 12 in a predetermined position. 127a, 127b, and 127c are formed.

(b) Fixed frame A
As shown in FIG. 6 (a), the fixed frame A21 includes a ring portion 210 into which the ring portion 120 of the movable frame 12 is inserted, and a first accommodating portion 212a that receives a part of the steel ball on the surface facing the movable frame 12. , 212b, 212c are formed with a flange portion 211. As shown in FIG. 6 (b), on the surface opposite to the surface facing the movable frame 12 of the flange portion 211 of the fixed frame A21, a holding hole for holding the columnar first attracting magnets 214a, 214b, 214c 213a, 213b, and 213c are formed.

(c) Fixed frame B
As shown in FIG. 7 (a), the fixed frame B41 includes a ring portion 410 for guiding a fourth lens group (not shown), and a flange portion 411 on which fixed portions 412a, 412b, 412c are formed. Have. As shown in FIG. 7B, a holding hole 413 for holding the magnetic shield plate 414 (see FIG. 3) is formed on the side of the flange portion 411 facing the movable frame 12.

(d) Locking movable frame The locking movable frame 42, which is a member that forms a locking mechanism section described later, prevents buffering with the fixed frame B41 as shown in FIG. Holding holes for holding the back yoke 423 for locking and the magnets 424a, 424b for locking as well as having arc grooves 420a, 420b, 420c for equal rotation along the circumferential direction. A holding portion 421 having 422 is included. As shown in FIG. 8 (b), the locking pins 425a, 425b, and 425c that fit into the locking holes 128a, 128b, and 128c described above are formed on the side of the locking movable frame 42 that faces the movable frame 12. Has been.

(e) Support means In the present embodiment, a sphere made of a ferromagnetic material such as a steel ball is used as the rolling element 13 (see FIG. 2), and the rolling element 13 can be held mechanically and magnetically. . That is, a ring-shaped first accommodating portion 212a that receives a part of a steel ball at a predetermined angular interval (for example, 120 °) along the circumferential direction on the flange portion 211 (side facing the movable frame 12) of the fixed frame A21, 212b and 212c are formed, and columnar first attracting magnets 214a, 214b, and 214c magnetized in the Z-axis direction are embedded on the back side of the housing portion. Ring-shaped second accommodating portions 122a, 122b, 122c that receive a part of the steel ball are formed on the flange portion 121 (the side facing the fixed frame A21) of the movable frame 12, and on the back side of the accommodating portion. Columnar second magnets 125a, 125b, 125c magnetized in the axial direction and suction back yokes 126a, 126b, 126c are embedded. Accordingly, since a plurality (three) of steel balls are sandwiched between the fixed frame A and the movable frame, the movable frame 12 moves in an arbitrary direction within a plane perpendicular to the Z axis with respect to the fixed frame A21. Can do. Moreover, since the steel balls are magnetically attracted and held in the Z-axis direction, undesired movement of the steel balls can be suppressed.

(3) Correction Voice Coil Motor The correction VCM 3 that drives the correction lens 11 is of a movable magnet type, so that the wiring is not routed by the movement of the motor and the coil can be prevented from being disconnected. As shown in FIGS. 2 to 4, the movable magnet type correcting VCM 3 is fixed to the movable member 1 side and the coil portion 31 including the flat coils 310a, 310b, 310c fixed to the fixed member 2 side. The magnetic circuit unit 32 includes permanent magnets 321a, 321b, and 321c and yokes 320a, 320b, and 320c. Each permanent magnet 321a, 321b, 321c has a circumferential length larger than the radial width and matches the effective length of the flat coil in the circumferential direction. It is installed so as to line up in the direction. By installing each of the permanent magnets 321a, 321b, and 321c in this way, a thrust in the radial direction is generated in a plane perpendicular to the optical axis, and by combining the thrusts, an arbitrary direction is generated in the plane perpendicular to the optical axis. The correction lens 11 can be driven. In the present embodiment, the correction VCM 3 is configured by arranging three flat coils so as to circumscribe the reference circle at equiangular intervals (120 °). However, in the present invention, the angular interval is at least 90 °. It is preferable to arrange so that the angle becomes. For example, two of the three flat coils may be arranged at an angular interval of 90 °, and the remaining one may be arranged at an angular interval of 135 ° from the two flat coils. Further, four or more flat coils may be provided.

(a) Coil part The flat coils 310a, 310b, 310c constituting the coil part 31 are flat air-core coils wound in an oval shape (race track shape) when viewed from the optical axis direction, and the wiring board 22 Is formed of a plurality of flat coils 310a, 310b, 310c installed on one surface of the fixed member 2, that is, the surface facing the movable frame 12. The flat coils 310a, 310b, 310c are fixed to the fixed frame A21 at equal angular intervals (120 ° intervals) along the circumferential direction. In the vicinity of each of the flat coils 310a, 310b, 310c or each of the permanent magnets 321a, 321b, 321c, for example, a magnetic field detection element (such as a hall element) described later is provided as position detection means. In this example, the Hall elements 610a, 610b, 610c (see FIG. 3) are located on the surface of the wiring board 22 opposite to the surface where the flat coils 310a, 310b, 310c are installed, and at positions corresponding to the air cores of the coils. ) Is installed.

(b) Magnetic circuit unit The magnetic circuit unit 32 is fixed to magnetic circuit holding units 123a, 123b, 123c formed at a plurality of locations (three locations in the present embodiment) of the flange portion 121 of the movable frame 12. A plurality of permanent magnets 321a, 321b, 321c (the same number as the flat coils) provided at a position facing a plurality (three in this embodiment) of the flat coils 310a, 310b, 310c, and the permanent magnets 321a, 321b , 321c flat coils 310a, 310b, 310c and flat yokes 320a, 320b, 320c provided on the opposite surface. The correction lens 11 can be driven by the magnetic field generated by the magnetic circuit unit 32 and interlinked with the flat coils 310a, 310b, 310c. These permanent magnets 321a, 321b, and 321c are all magnetized in the thickness direction (optical axis direction), a pair of magnetic poles having different polarities exist on the surface facing the flat coils 310a, 310b, and 310c, and the magnetic poles Is magnetized so that the boundary (magnetization neutral line) is directed in the tangential direction of a circle centering on the central axis (coincidence with the optical axis) of the movable member 1. Therefore, the effective conductor part of the coil that contributes to the generation of thrust by interlinking with the magnetic flux generated from the permanent magnets 321a, 321b, and 321c is configured to be the straight part of the coil (the part indicated by hatching in FIG. 9). ing. These permanent magnets 321a, 321b and 321c have a length Lm in FIG. 9 larger than the coil width W1 in order to obtain a large thrust with a low driving current, and in particular, Lm / W1 is in the range of 1.5 to 2.0. Is preferred.

  Permanent magnets 321a, 321b, and 321c consist of a single permanent magnet (block-shaped permanent magnet) formed with a pair of magnetic poles (N pole and S pole) as shown in FIG. Alternatively, a pair of block permanent magnets (monopolar magnets) magnetized in the thickness direction may be prepared, and those magnets fixed so that the magnetization directions may be different. When forming a pair of magnetic poles in one magnetizing operation, it is preferable to magnetize using a highly magnetized permanent magnet having a coercive force of 20 KOe or less. Since these permanent magnets have a linear magnetic field change at the portion where the N pole is inverted to the S pole, accurate position detection can be performed.

(4) Locking mechanism section The locking mechanism section 4 is provided on the locking movable frame 42 that holds (locks) the fixed frame B41 and the movable frame 12 at predetermined positions, and rotates the locking movable frame 42. A locking voice coil motor (hereinafter simply referred to as “locking VCM”) 40 is provided. The locking VCM 40 includes a locking coil 415 (flat air core coil) fixed to the fixed frame B41 via the wiring board 43, a locking suction yoke 416, and a locking frame 415 on the opposite side of the fixing frame B41. A magnetic shield plate 414 fixed to the surface, locking magnets 424a and 424b and locking back yoke 423 provided on the locking movable frame 42 and magnetized in the thickness direction are provided. By supplying a driving current to the locking coil 415, the locking magnets 424a and 424b with the locking back yoke 423 are rotated in a predetermined direction so that the locking movable frame 42 is fitted to the movable frame 12, and the correction lens is used. 11 can be fixed at a position whose center coincides with the optical axis of the lens barrel. The locking mechanism unit 4 can hold the correction lens 11 in a fixed state (coaxial with the optical axis) without energization. The rotation range of the locking movable frame 42 can be set by providing the fixed frame B with a regulating member (not shown) such as a magnetic pin. The wiring board 43 is preferably a flexible wiring board (FPC).

  FIG. 11 shows a locking portion 127a having a locking groove 128a provided in the movable frame 12, and a locking pin 425a provided in the locking movable frame. FIG. 11 shows only one of the three locking structures constituted by the locking portions 127a, 127b, 127c, the locking grooves 128a, 128b, 128c and the locking pins 425a, 425b, 425c. Since other parts have the same shape, the description thereof is omitted. The movable frame 12 is locked so that the locking pin 425a of the locking movable frame 42 is inserted into the locking portion 127a on the side facing the locking movable frame 42 when the locking movable frame 42 rotates. A groove 128a is provided. This locking groove 128a has a shape in which the side on which the locking pin 425a of the locking movable frame 42 is inserted is open, and has a width on the back side (h1) than the width (h1) of the entrance into which the locking pin 425a is inserted. h2) is more widely formed. The length (la) of the groove is about twice the diameter of the locking pin 425a and is set so that h2> h1. Since the locking groove 128a has such a shape, when the locking pin 425a is pushed in (when the camera shake correction unit is in a locked state), the locking groove 128a smoothly enters the locking groove 128a, and is easily caused by some vibration or the like. Therefore, a reliable locking operation can be guaranteed.

  As shown in FIGS. 12 and 13, the locking VCM 40 includes a locking coil 415 (flat air core coil) fixed to the fixed frame B41 (fixed side member) via the wiring board 43, and a locking movable Magnetic field generating means fixed to the frame 42 (movable side member), that is, a movable magnet provided with locking magnets 424a and 424b and a locking yoke 423 that are magnetized in the thickness direction and have opposite polarity magnetic poles facing the coil Magnet type. A locking suction yoke 416 is fixed to the surface of the fixed frame B41 facing the wiring board 43 at a position corresponding to the air core portion of the locking coil 415, and strong on the back side of the fixed frame B41. A magnetic shield plate 414 made of a magnetic material is provided. Further, the fixing frame B41 is provided with restriction members 417a and 417b at both ends of the rotation range of the locking magnets 424a and 424b in order to limit the rotation range of the locking magnets 424a and 424b. The restricting member is made of a ferromagnetic material such as a steel material so that the permanent magnet can be magnetically attracted.

  A pair of rectangular parallelepiped locking magnets 424a and 424b magnetized in the thickness direction (optical axis direction) are adjacent to each other in the plane perpendicular to the optical axis along the circumferential direction. It is fixed to the holding frame 421. These locking magnets 424a and 424b can be formed of a known permanent magnet material, but are represented by Nd-Fe-B anisotropic sintered magnets in order to reduce the size of the VCM 40. It is preferable to use rare earth magnets. Nd-Fe-B anisotropic sintered magnets are formed in a magnetic field in which the orientation magnetic field is perpendicular to the molding direction (press direction) (perpendicular magnetic field molding) or in a magnetic field in which the orientation magnetic field is parallel to the molding direction (press direction). In the present invention, the locking magnet (magnetic field generating means) is formed by compression molding in a magnetic field perpendicular to the molding direction and in the same direction as the molding direction. It consists of a pair of magnetized Nd-Fe-B anisotropic sintered magnets in the shape of a magnet, and each sintered magnet is arranged in a fan shape so that magnetic poles of different polarities are adjacent to each other when viewed from the optical axis direction It is preferable.

  For example, as shown in FIG. 13 (a), in a plane perpendicular to the optical axis, the rectangular parallelepiped locking magnets 424a and 424b are spaced apart by an angle γ on the circumference around the optical axis. The long sides of the locking magnets 424a and 424b are arranged so as to coincide with the tangential direction of the circle. The angle γ is preferably 15 to 25 °, and is preferably set so that the locking magnet 424a and the locking magnet 424b are in contact with each other. By disposing the locking magnets 424a and 424b in this way, when the locking magnets 424a and 424b are in contact with the regulating members 417a and 417b, that is, when the camera shake correction unit is in the locked state or the unlocked state. Since the thrust of the locking VCM 40 is maximized, a reliable locking operation can be performed, and the switching from the locked state (unlocked state) to the unlocked state (locked state) can be performed smoothly.

  As shown in FIG. 13 (b), the locking coil 415 has an effective winding portion that contributes to the generation of thrust in the optical axis direction view, about 1/3 to about 1/2 of the locking magnets 424a, 424. It is preferable that the projected area is as follows. As shown in FIG. 13 (c), the locking back yoke 423 has a locking magnet 424a as viewed in the optical axis direction in order to effectively focus the magnetic flux generated from the locking magnets 424a and 424 on the coil side. , 424 is preferable. The magnetic shield plate 414 has a shape that covers at least the projected portion of the entire moving range of the locking magnets 424a and 424 and can be shielded as widely as possible in order to ensure the magnetic shielding effect. preferable.

A cuboid permanent magnet (perpendicular magnetic field molded product) is not easily disturbed in orientation during molding, so it has high magnetic properties (for example, a residual magnetic flux density of 1.45 to 1.51 T and a maximum energy product of 405 to 437 kJ / m ³ (51 to 55 MGoe) can thus be used, and thus a rectangular parallelepiped permanent magnet can be used as a locking magnet in this way, so that the locking force (holding force at the end of the movable range) can be obtained. In the non-imaging mode, the correction lens can be securely held at the center of the lens barrel, and the rectangular parallelepiped permanent magnet can be used without using a molding die having a special shape. Since it can be manufactured, it is advantageous in terms of cost compared to a permanent magnet of complicated shape (arc shape, etc.), and full magnetization is possible with an air-core coil without using a magnetizing device with a special structure, Also has the advantage of obtaining permanent magnets with high magnetic properties

  A driving current is supplied to the locking coil 415, and the locking magnets 424a and 424b are rotated in a predetermined direction within a plane perpendicular to the optical axis to move the locking pins 425a, 425b, and 425c of the locking movable frame 42. By fitting (holding) into the locking grooves 128a, 128b, 128c of the frame 12, the correction lens 11 can be fixed at a position where the center thereof coincides with the optical axis of the lens barrel. At the end of the rotation range of the locking movable frame 42, the driving magnets 424a and 424b are attracted to the regulating members 417a and 417b made of a ferromagnetic material, thereby stopping the drive current supplied to the locking coil 415. Even so, a so-called self-holding VCM that can hold the locked state (or unlocked state) can be obtained. In this self-holding type VCM 40 for locking, the holding force can be adjusted by changing the material, size, quantity, and the like of the regulating members 417a and 417b.

  In the above locking mechanism portion, as shown in FIG. 12, by providing the locking suction yoke 416 at the center of the locking VCM 40 on the fixed frame B41 side, the lifting of the locking movable frame 42 is suppressed, The holding force can be increased. Furthermore, by providing a magnetic shield plate 414 made of a ferromagnetic material on the back surface of the region sandwiched between the restricting members 417a and 417b of the fixed frame B41, the magnetic field generated from the locking magnets 424a and 424b can be reduced inside the correction unit. Therefore, leakage magnetic flux is reduced, and adverse effects on members provided around the camera shake correction unit can be prevented.

(5) Position detection means In the present invention, as shown in FIG. 10, the position information of the movable frame 12 (not shown) including the correction lens 11 is detected by the magnetic force of the magnetic circuit section 32 of the correction VCM 3. Position detection means (lens position detection unit 61) for outputting the detection signal as a voltage is installed on the wiring board 22 of the fixing member 2. In the present embodiment, the Hall element is located at a position corresponding to the air core portion of each flat coil 310a on the second surface 222 opposite to the first surface 221 on which the flat coil 310a of the wiring board 22 is installed. 610a is installed. The magnetic flux density in the optical axis direction detected by the Hall element 610a when the magnetic circuit unit 32 is moved in the radial direction is, for example, a sine wave shape as shown in FIG. The magnetic flux density varies linearly in a narrower range.

  Here, for example, as shown by a two-dot chain line in FIG. 10, when the Hall element 610d is disposed on the first surface 221 of the wiring board 22 in the vicinity of the surface of the permanent magnet 321a, the Hall element with respect to the moving amount of the movable frame is arranged. The linearity of the output of 610d is degraded. On the other hand, as shown in the embodiment, the Hall element 610a is disposed on the second surface 222 of the wiring board 22 as shown by a solid line in FIG. 10, so that the distance between the Hall element 610a and the permanent magnet 321a is increased. And the nonlinearity of the magnetic flux density distribution is relaxed, and the output voltage changes almost linearly. Therefore, the position information of the movable part (permanent magnet) can be detected with high accuracy. However, if the distance between the Hall element 610a and the permanent magnet 321a becomes excessive, the output voltage of the Hall element decreases, so that it is necessary to increase the power supply voltage and the noise also increases. Therefore, for example, when an element made of GaAs is used as the Hall element and an NdFeB-based sintered magnet ((BH) max = 45 to 50 MGOe) is used as the permanent magnet, the distance between them is preferably 1.3 to 2.0 mm.

  Further, by installing the Hall element 610a on the second surface 222 of the wiring board 22, a wide space for pulling out the coil terminal and soldering to the wiring board 22 can be secured. Therefore, unlike the prior art, it is not necessary to increase the inner diameter of the coil in order to secure a soldering space, and an increase in the coil size can be prevented. However, when the Hall element 610a is arranged in this way, the output voltage of the Hall element 610a decreases because the Hall element 610a moves away from the permanent magnet 321a. Therefore, in order to ensure the same level of sensitivity as before, the amplification factor of the output voltage is increased. In addition, it is preferable to employ a circuit configuration in which a noise filter is further added so that noise can be removed.

  As the magnetic field detection element, as described above, a magnetic sensor of a type that outputs an analog signal voltage proportional to the magnetic flux density (linear output) such as a Hall element can be used. The Hall element is usually formed of an N-type semiconductor thin film (thickness of several μm) made of a III-V group compound such as GaAs, InSb, InAs, etc., and its output voltage depends on the electron mobility and Hall coefficient of the material. . In order to enable highly accurate position control, it is preferable to use a Hall element formed of GaAs having a small Hall coefficient temperature coefficient (about −0.06% / ° C.). In addition to compound systems, a Hall IC that integrates a Hall element made of Si and a signal processing circuit such as an operational amplifier can be used. However, since the Hall element made of Si has low sensitivity, the offset voltage of the Hall element and the operational amplifier is low. And a circuit configuration having a temperature compensation function is required. In addition to the Hall element, an MR element using the magnetoresistive effect, an MI element using the magnetoimpedance effect, and the like can be used as the magnetic field detection element. However, considering the practicality such as the cost in addition to the resolution, the Hall element A magnetic field detection element having a resolution of about 10 μT like the element is suitable.

  When the magnetic pole boundary 321d of the permanent magnet 321a (indicated by a broken line in FIG. 10) is located at the center of the Hall element 610a, the magnetic field in the optical axis direction of the permanent magnet 321a is zero, so the output voltage of the Hall element 610a is almost zero. Become. When the permanent magnet 321a moves in the direction of arrow E or F in FIG. 10, a voltage proportional to the moving distance is output from the Hall element 610a. Based on this output voltage, the movement distance of the Hall element 610a is calculated, and the movement amount of the correction lens 11 is obtained.

(6) Magnetic circuit forming material As the permanent magnets 321a, 321b, and 321c constituting each correction VCM3 described above, known permanent magnets (for example, rare earth magnets) can be used, but the drive current supplied to the coil In order to reduce (direct current) and obtain a high thrust, it is preferable to use an RFeB-based permanent magnet (R is at least one selected from rare earth elements including Y and necessarily contains Nd), particularly 45 MGOe. It is preferable to use an Nd—Fe—B anisotropic sintered magnet having the above maximum energy product.

  Each of the yokes 320a, 320b, and 320c is a member that becomes a magnetic path, and can be formed of a ferromagnetic material, for example, a steel material such as an SS material.

[3] Camera shake correction operation The camera shake correction operation is executed by, for example, the control algorithm shown in FIG. The camera shake amount detected by the camera shake amount detection unit 5 including the gyro sensor (for example, the angular velocity of the camera body shake) is converted into the camera shake angle by the camera shake amount calculation unit 62, and the lens position information (lens position information detection unit 61) Along with the information on the shooting mode determined by the shooting mode determination unit 63 from the shutter and mode switch information (shutter switch / mode switch 64), a correction amount calculation unit 65 calculates a camera shake correction amount (amount of movement of the correction lens 11). The voltage signal is output to the VCM drive circuit 7. By driving the correction lens 11 (see Fig. 2) according to this correction amount, the incident optical axis (Z'-axis direction in Fig. 1) fluctuated due to camera shake is shifted in the Z-axis direction, and image displacement is corrected. Thus, an optical image in which camera shake is suppressed can be obtained.

(1) Operation of Correction VCM FIG. 9 shows flat coils 310a, 310b, 310c provided on the wiring board 22, yokes 320a, 320b, 320c and permanent magnets 321a, provided on a movable frame (not shown). The relationship with the magnetic circuit unit 32 composed of 321b and 321c is schematically shown. When one or more of the flat coils 310a, 310b, 310c of the correction VCM3 are fed, each magnetic circuit section 32 has a radius in a plane (XY plane) perpendicular to the optical axis direction according to Fleming's left-hand rule. Directional thrusts Fa1, Fb1, and Fc1 are generated. Of each flat coil, the winding of the portion interlinking with the magnetic flux of the permanent magnet (the portion indicated by hatching in FIG. 9) is an effective conductor portion that contributes to the thrust. By adjusting the current supplied to each coil, thrust can be generated in an arbitrary direction on a plane perpendicular to the optical axis.

  For example, when currents of the same polarity and magnitude are applied to three flat coils, the direction and magnitude of the thrust (Fa1, Fb1, Fc1) generated in each magnetic circuit section are the same, and the thrust in the X direction (Fx) and Y The direction thrust (Fy) is zero, and the movable frame is stopped.

The energization pattern of one of the three coils is different from the energization pattern of the other coils (for example, the currents Ia and Ib applied to the flat coils 310a and 310b are expressed as Ia = Ib = −I ₁ , flat coil The current Ic applied to 310c is Ic = I ₁ ), and only the correction VCM configured by the flat coil 310c has the thrust direction opposite, and as a result, the thrust Fx in the X direction is
Fx ＝ Fa1 ・ cosθ1 ＋ Fb1 ＋ Fc1 ・ cosθ2,
Y direction thrust Fy is
Fy ＝ Fa1 ・ sinθ1 ＋ Fc1 ・ sinθ2,
It becomes. Therefore, the movable frame can be moved in the X direction and the Y direction with thrusts of Fx and Fy, respectively.

  As described above, by having the magnetic pole arrangement as shown in FIG. 9, the thrust can be adjusted by changing the polarity and / or magnitude of the current supplied to each coil, and the correction lens is a surface perpendicular to the optical axis. Can move in any direction. As a result, the camera shake correction operation can be performed effectively.

On the other hand, in the conventional VCM described in Patent Document 1, for example, since the magnetization neutral line of the permanent magnet is in the radial direction, the flat coil must be formed in a rectangular shape (see FIG. 5 of Patent Document 1). b)), the area of the effective conductor portion is extremely smaller than that of the flat coil constructed in the present invention (about 1/4 or less of the correction VCM constructed in the present invention). That is, in the present invention, the amount of magnetic flux that contributes to thrust among the magnetic flux generated from the permanent magnet is increased as compared with the case of the prior art, so that a large thrust can be obtained even if the current supplied to the coil is the same. Thereby, even when the aperture of the correction lens increases (the weight of the movable member increases), the correction lens can be moved quickly, and the application range of the camera shake correction unit can be expanded. In other words, the battery consumption is reduced, and it can also be applied to interchangeable lenses with a large aperture and a large open F value, so the viewfinder is easy to see, and even at dark scenes, you can close the aperture and shoot at a slow shutter speed. It has the advantage that it becomes possible.

(2) Position Detection Operation As shown in FIG. 16, in the lens barrel 114, Hall elements 610a, 610b, and 610c for detecting the position of the correction lens 11 are arranged along with the correction VCM 3 for driving the correction lens 11. It is installed. Each Hall element 610a, 610b, 610c is connected to AD converters (ADC) 612a, 612b, 612c via position signal processing circuits 611a, 611b, 611c that output the position of the correction lens 11 as a voltage signal. Here, when the sensitivity center of the Hall elements 610a, 610b, 610c is located at the magnetic pole boundary (position where the polarity is reversed), the output voltage from the Hall elements 610a, 610b, 610c is zero, but the Hall element is in the X direction. When driven in the Y direction, the output voltage changes in proportion to the magnetic flux density, and this output voltage is output as a position signal.

  The position signals detected by the Hall elements 610a, 610b, and 610c (the amount of movement of the movable member including the permanent magnet) are amplified to a predetermined magnification by a signal processing circuit including an operational amplifier, and the position signals (Halls) from the signal processing circuit are amplified. A current proportional to the difference between the position of the movable member detected by the element) and a coil position command signal (a signal indicating the position where the correction lens 11 should be moved in accordance with the amount of camera shake correction) is supplied to the drive coil. When there is no difference between the output from the signal processing circuit and the coil position command signal, the drive current to the coil stops and the thrust of the correction VCM becomes zero.

100: camera,
110: Body, 111: Solid-state image sensor, 112: Optical filter,
114: lens barrel, 115a: first lens group, 115b: second lens group, 115c: third lens group, 115d: fourth lens group,
10: Image stabilization unit,
1: movable member, 11: correction lens,
12: movable frame, 120: ring part, 121: flange part, 122a, 122b, 122c: second housing part, 123a, 123b, 123c: magnetic circuit holding part, 124a, 124b, 124c: holding groove, 125a, 125b, 125c: second attraction magnet, 126a, 126b, 126c: back yoke for attraction, 127a, 127b, 127c: locking portion, 128a, 128b, 128c: locking groove,
13: rolling element,
2: Fixed member,
21: Fixed frame A, 210: Ring part, 211: Flange part, 212a, 212b, 212c: First housing part, 213a, 213b, 213c: Holding hole, 214a, 214b, 214c: First attracting magnet,
22: wiring board, 221: first surface, 222: second surface,
3: Voice coil motor for correction (VCM for correction),
31: Coil part, 310a, 310b, 310c: Flat coil,
32: Magnetic circuit section, 320a, 320b, 320c: Yoke, 321a, 321b, 321c: Permanent magnet, 321d: Magnetic pole boundary,
4: Locking mechanism,
40: Voice coil motor for locking (VCM for locking),
41: Fixed frame B, 410: Ring part, 411: Flange part, 412a, 412b, 412c: Fixed part, 413: Holding groove, 414: Magnetic shield plate, 415: Locking coil, 416: Suction yoke for locking, 417a, 417b: restriction members,
42: Locking movable frame, 420a, 420b, 420c: Arc groove, 421: Holding part, 422: Holding hole, 423: Locking back yoke, 424a, 424b: Locking magnet, 425a, 425b, 425c: Engagement Stop pin
43: Wiring board,
5: shake amount detection unit,
6: Control circuit,
61: Lens position detection unit, 62: Shake amount calculation unit, 63: Shooting mode discrimination unit, 64: Shutter switch / mode switch, 65: Correction amount calculation unit, 610a, 610b, 610c: Hall element, 611a, 611b, 611c : Position signal processing circuit, 612a, 612b, 612c: AD converter,
7: VCM drive circuit.

Claims (5)

A fixing member made of a non-magnetic material fixed in the lens barrel;
A ring-shaped movable member arranged to face the fixed member as viewed from the optical axis direction and supporting the correction lens;
Support means for supporting the movable member movably in a plane perpendicular to the optical axis of the correction lens;
A plurality of correcting voice coil motors that move the movable member in a plane perpendicular to the optical axis;
Control means for controlling the moving direction and moving amount of the correcting voice coil motor;
A locking member provided with a locking pin for locking the movable member;
A camera shake correction unit including a locking movable magnet type voice coil motor for driving the locking member;
The locking movable magnet type voice coil motor includes an air core coil provided on the fixed member, a suction yoke provided on an air core portion of the air core coil, and a magnetic field generation provided on the locking member. And a restricting member made of a ferromagnetic material provided at both ends of the movable range of the magnetic field generating means.   2. The camera shake correction unit according to claim 1, wherein the movable member has a locking groove for receiving the locking pin and locking the movable member when the locking member is rotated. The image stabilization unit according to claim 1, wherein the stop groove has a shape in which the back side is wider than the entrance side along the moving direction of the locking pin.   3. The camera shake correction unit according to claim 1, wherein the locking voice coil motor includes a magnetic shield member provided on the fixed member over a movable range of the magnetic field generation unit. Correction unit.   The camera shake correction unit according to any one of claims 1 to 3, wherein the magnetic field generating means is a pair of rectangular parallelepiped Nd- that is compression-molded in a magnetic field perpendicular to the molding direction and magnetized in the same direction as the molding direction. Camera shake correction characterized by comprising an Fe-B anisotropic sintered magnet and each of the sintered magnets being arranged in a substantially fan shape so that magnetic poles of different polarities are adjacent when viewed from the optical axis direction unit. 5. The camera shake correction unit according to claim 1, wherein the correction voice coil motor includes a plurality of oblong flat air-core coils provided on the fixed member, and the movable member. Consists of a plurality of magnetic circuit portions provided at positions corresponding to the air-core coil,
The air-core coil has a longitudinal direction that coincides with a tangential direction at an angular interval of 90 to 120 ° on a circumference centered on the optical axis in a plane orthogonal to the optical axis direction of the fixing member. Arranged as
The magnetic circuit section is fixed so that a flat plate-shaped yoke made of a ferromagnetic material fixed to the movable member and a pair of magnetic poles of different polarity are opposed to the air-core coils. Including a plurality of flat permanent magnets,
The camera shake correction unit, wherein the permanent magnet is installed such that a pair of magnetic poles having different polarities face the optical axis in a plane orthogonal to the optical axis direction.

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