JPWO2011142153A1 - Image stabilization unit - Google Patents

Abstract

A fixed member, a movable member that supports the correction lens, a support unit that supports the movable member so as to be movable in a plane perpendicular to the optical axis, an air-core coil provided on the fixed member via a wiring board, and A camera shake correction unit including a movable magnet type voice coil motor configured by a magnetic circuit unit provided at a position corresponding to the air-core coil of the movable member, wherein the support means includes a movable member, a fixed member, Are sandwiched between a plurality of permanent magnets provided on each of the movable member and the fixed member, and a plurality of permanent magnets provided on the movable member and a plurality of permanent magnets provided on the fixed member. It is characterized by comprising a plurality of rolling elements made of a ferromagnetic material and an accommodating portion for accommodating a part of the rolling elements.

Description

  The present invention relates to a camera shake correction unit including movable magnet type driving means for moving a camera shake correction lens in order to prevent image shake due to a shake applied to an optical apparatus.

  In an imaging optical device such as a digital camera, a camera shake prevention mechanism is generally mounted on a camera body or an interchangeable lens in order to take a high-quality photograph in accordance with the longer focus and higher magnification zoom of a taking lens. It has become.

  Analyzing camera shake during photography, it is orthogonal to the optical axis due to shaking of the arm (frequency around 10 Hz), shaking of the body (frequency around several Hz), and shutter impact and shaking of the hand during release. It is classified into parallel shake in the direction (vertical and horizontal) and rotational shake of pitch, yaw and roll. 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.

  As a method of translating and rotating the correction lens on a plane perpendicular to the optical axis, for example, Japanese Patent Application Laid-Open No. 2007-86808 discloses a fixed plate fixed in a lens barrel and movable relative to the fixed plate. Disclosed is an actuator having a translation frame with a supported movement frame and three steel balls supporting the movement frame. This actuator has three driving magnets attached to the moving frame, a driving coil attached to the position of the fixed plate corresponding to the driving magnet, and an adsorption for attracting the moving frame by the magnetic force of the driving magnet. The parallel movement device has a spherical magnet for attracting a spherical body such as a steel ball to the moving frame, and the steel ball smoothly rolls between the fixed plate and the moving frame. And a steel ball receiver (support plane portion) attached to the fixed plate and the moving frame.

  However, the translation device described in Japanese Patent Application Laid-Open No. 2007-86808 has a problem that the steel ball is not sufficiently held because the steel ball is sandwiched between the flat plate members. Further, the actuator described in JP-A-2007-86808 is provided with a suction yoke at a position corresponding to the drive magnet, and the drive magnet is used not only for driving but also for attracting the moving frame. The thrust generated in the actuator and the magnetic attractive force between the drive magnet and the yoke cannot be controlled independently. That is, when the distance between the driving magnet and the yoke is changed, both the thrust of the actuator and the magnetic attractive force between the driving magnet and the yoke change.

  For example, if the distance between the drive magnet and the yoke is reduced to increase the thrust, the permeance coefficient increases and the operating point moves in the direction of increasing the magnetic flux density, so the magnetic attractive force between the drive magnet and the yoke Will increase. As a result, the load applied to the steel ball increases and the durability decreases. On the other hand, if the distance between the drive magnet and the attracting yoke is set wide so that an excessive load does not act on the steel ball, the thrust generated by the actuator decreases. That is, when a structure in which an attracting yoke is provided at a position corresponding to the drive magnet and the moving frame is attracted by the magnetic force of the drive magnet as in the actuator described in Japanese Patent Application Laid-Open No. 2007-86808 is adopted, the magnetic circuit of the actuator It is difficult to configure the unit so that an appropriate thrust or magnetic attractive force can be obtained.

  In Japanese Patent Laid-Open No. 2008-15349, three steel balls are arranged between a fixed frame and a moving frame with a central angle of 120 °, and each steel ball is positioned at a position corresponding to each steel ball of the moving frame. An actuator is disclosed that is attracted to a moving frame by an embedded attracting magnet, and the moving frame is attracted to a fixed frame by a driving magnet. The moving frame is supported in a state in which each steel ball is sandwiched on a plane parallel to the fixed frame, and can translate and rotate in an arbitrary direction by rolling each steel ball. However, the actuator described in Japanese Patent Application Laid-Open No. 2008-15349, like the actuator described in Japanese Patent Application Laid-Open No. 2007-86808, has a steel ball that is sandwiched between flat plate members, so that the steel ball is not sufficiently held. Have the problem of becoming.

  Japanese Patent Application Laid-Open No. 2006-215122 discloses an image that is installed in a lens barrel and includes a correction lens that decenters an optical axis, a driving unit for the correction lens, and a holding unit for the correction lens with respect to a fixed portion of the lens barrel. A shake prevention device is disclosed. Japanese Patent Laid-Open No. 2006-215122 discloses that as the holding means, three steel balls are interposed between three disk magnets embedded in the holding frame of the fixed part and three disk magnets embedded in the support frame of the movable part. An intervening holding mechanism is disclosed, and it is described that this holding mechanism enables omnidirectional movement by rolling a steel ball between disk magnetic poles composed of counter electrodes. However, since the holding mechanism described in JP-A-2006-215122 has a structure in which the steel balls are sandwiched between the disk-shaped members, the steel balls are magnetically held, but the moving range of the steel balls is not widened. There is a problem that necessary movement cannot be regulated.

  Accordingly, an object of the present invention is to provide a camera shake correction unit that includes a movable magnet type correction lens driving unit, and has a supporting unit that can keep the moving range of the movable member within an appropriate range without affecting the driving unit. Is to provide.

  As a result of diligent research in view of the above object, the inventors of the present invention have developed a rolling element housing portion having a permanent magnet for magnetically attracting the rolling element on the movable member and the fixed member. A plurality of support members provided along the circumferential direction, sandwiching a plurality of rolling elements made of a ferromagnetic material, and supporting means configured so that a magnetic attractive force acts between the movable member and the fixed member via the rolling elements, The present inventors have found that the movable range of the movable member can be within an appropriate range and have arrived at the present invention.

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 oblong flat air-core coils provided on the fixed member, and a plurality of magnetic circuit portions provided on the movable member at positions corresponding to the air-core coils, A movable magnet type voice coil motor that moves a movable member in a plane orthogonal to the optical axis of the correction lens;
A camera shake correction unit comprising control means for controlling the moving direction and moving amount of the voice coil motor,
The air-core coil is arranged on a circumference centered on the optical axis in a plane orthogonal to the optical axis direction of the fixing member so that the longitudinal direction coincides with the tangential direction,
The magnetic circuit section is fixedly provided so that a flat plate yoke made of a ferromagnetic material fixed to the movable member, and a pair of magnetic poles fixed to the yoke and opposite in polarity to the air-core coils are opposed to each other. Including a plurality of flat permanent magnets,
The support means includes a plurality of permanent magnets respectively provided on the movable member and the fixed member so that a magnetic attractive force acts between the movable member and the fixed member, and a plurality of permanent magnets provided on the movable member. A plurality of rolling elements made of a ferromagnetic material sandwiched between a permanent magnet and a plurality of permanent magnets provided on the fixed member, and a part of the rolling elements provided at positions corresponding to the permanent magnets It is characterized by comprising an accommodating portion for accommodating.

  It is preferable that a suction back yoke is provided on the side opposite to the side facing the fixed member of the plurality of permanent magnets provided on the movable member.

  It is preferable that a suction back yoke is provided on the side opposite to the side facing the movable member of the plurality of permanent magnets provided on the fixed member.

  The outer diameter of the suction back yoke is preferably larger than the outer diameter of a plurality of permanent magnets provided on the movable member.

  It is preferable that the flat permanent magnets forming the magnetic circuit portion are arranged on a circumference centered on the optical axis so that a magnetic neutral line coincides with a tangential direction.

  According to the present invention, the correction lens can be smoothly moved, the movement range thereof can be adjusted appropriately, and the correction lens can be quickly returned to the operation center. Furthermore, by installing permanent magnets that constitute the motor for driving the correction lens so that the magnetization neutral line coincides with the tangential direction, it is possible to increase the number of effective conductors that contribute to thrust and increase power consumption. Therefore, it is possible to increase the thrust force, and to drive a correction lens having a large diameter.

It is the schematic which shows an example of the digital camera carrying the camera-shake correction unit of this invention. It is a disassembled perspective view which shows an example of the camera-shake correction unit of this invention. FIG. 3 is an exploded perspective view of FIG. 2 viewed from the A direction. FIG. 3 is a sectional view taken along line BB in FIG. FIG. 3 is a perspective view showing a movable frame of the camera shake correction unit in FIG. 2 as viewed from the C direction. FIG. 6 is a perspective view of the movable frame in FIG. 5 (a) as seen from the back side. FIG. 3 is a perspective view showing the fixed frame A of the camera shake correction unit in FIG. 2 as viewed from the C direction. FIG. 7 is a perspective view of the fixed frame A in FIG. 6 (a) as viewed from the back side. FIG. 3 is a perspective view showing the fixed frame B of the camera shake correction unit of FIG. 2 as viewed from the C direction. FIG. 8 is a perspective view of the fixed frame B of FIG. 7 (a) as viewed from the back side. FIG. 3 is a perspective view showing a locking movable frame of the camera shake correction unit in FIG. 2 as viewed from the C direction. FIG. 9 is a perspective view of the locking movable frame in FIG. 8 (a) as seen from the back side. It is a schematic diagram for demonstrating the thrust generation mechanism of a voice coil motor. FIG. 10 is a cross-sectional view taken along the line DD of FIG. 9 showing the configuration of the coil portion and the Hall element. It is sectional drawing which shows the other structure of a coil part and a Hall element. It is sectional drawing which shows the further another structure of a coil part and a Hall element. FIG. 10 is a cross-sectional view taken along line E-E in FIG. 9, schematically showing the support means. It is sectional drawing which shows other support means typically. It is sectional drawing which shows other support means typically. It is sectional drawing which shows other support means typically. 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 graph which shows typically the prevention effect of magnetic leakage by an attraction back yoke. It is a block diagram which shows the position detection circuit of a correction lens.

[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 an element 111, and a plurality of lens groups (first lens group 115a, second lens group 115b, a 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 visually recognized on the viewfinder even while the subject is being observed. 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. 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 with respect to the optical axis, the camera shake correction unit drive unit (voice coil motor) is placed on a surface that passes through the center of gravity of the correction optical system and is perpendicular to the optical axis. Is preferred.

[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. A movable magnet type voice coil motor (hereinafter simply referred to as “voice coil motor”) 3 that is driven in a smooth plane, and a locking mechanism section 4 that keeps the correction lens 11 stationary at a position that coincides with the optical axis when not imaging. It has.

(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 non-magnetic 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 211, and a wiring board 22. The wiring board 22 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 support means including a plurality of rolling elements 13a, 13b, and 13c interposed therebetween, 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 equiangular intervals (120 °) along the circumferential direction, and between the magnetic circuit holding portions 123a, 123b, 123c, respectively. Second housing portions 122a, 122b, 122c into which a part of the steel balls can be inserted are formed. On the surface of the flange 121 opposite to the surface facing the fixed frame A21, as shown in FIG.5 (a), a disk-like shape is provided at a position corresponding to the second accommodating portions 122a, 122b, 122c. Holding grooves 124a, 124b, 124c for holding the back yokes 126a, 126b, 126c and the second attracting magnets 125a, 125b, 125c (see FIG. 4) are formed. The magnetic circuit holding portions 123a, 123b, and 123c are formed with locking portions 127a, 127b, and 127c having locking grooves 128a, 128b, and 128c for receiving locking pins that will be described later.

(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, cylindrical first attracting magnets 214a, 214b, 214c (see FIG. 4) Holding holes 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 groove 413 that holds 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 has arcuate grooves 420a, 420b, 420c at equal angular intervals along the circumferential direction, as shown in FIG. 423 and a holding part 421 having a holding hole 422 for holding a locking magnet 424 (see FIG. 4). As shown in FIG. 8 (b), the engagement movable frame 42 is fitted into the aforementioned engagement holes 128a, 128b, and 128c (see FIG. 5 (a)) on the side facing the movable frame 12. Locking pins 425a, 425b, and 425c are formed.

(e) Supporting means In this embodiment, the supporting means of the mechanism that holds the rolling elements 13a, 13b, and 13c (see FIG. 2) in a state of being sandwiched between the accommodating portions provided in the movable frame 12 and the fixed frame A21. Have. A permanent magnet is provided in the housing portion, and a spherical body made of a ferromagnetic material such as a steel ball is used as the rolling elements 13a, 13b, and 13c, whereby a magnetic attractive force is applied to the steel balls and held. Further, by forming at least a portion of the movable frame 12 and the fixed frame A21 in contact with the rolling element with a self-lubricating material (for example, engineering plastic such as POM), the rolling element can be slid more smoothly. .

  That is, a part of the rolling elements 13a, 13b, 13c (steel balls) is received at a predetermined angular interval (for example, 120 °) along the circumferential direction on the flange portion 211 (the side facing the movable frame 12) of the fixed frame A21. Ring-shaped first accommodating portions 212a, 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 accommodating portions. On the other hand, the ring-shaped second accommodating portions 122a, 122b, 122c that receive part of the rolling elements 13a, 13b, 13c are formed on the flange portion 121 (the side facing the fixed frame A21) of the movable frame 12, and this Cylindrical second attracting magnets 125a, 125b, 125c magnetized in the Z-axis direction and attracting back yokes 126a, 126b, 126c are embedded on the back side of the accommodating portion. Therefore, since the three rolling elements 13a, 13b, and 13c are sandwiched between the fixed frame A21 and the movable frame 12, the movable frame 12 is in any direction within a plane perpendicular to the Z axis with respect to the fixed frame A21. Can move. In addition, since the rolling elements 13a, 13b, and 13c are magnetically attracted and held in the Z-axis direction, unnecessary movement of the rolling elements 13a, 13b, and 13c can be suppressed (moving range is limited).

  FIG. 11 schematically shows a cross section including the first storage portion 212a provided in the fixed frame A21, the second storage portion 122a provided in the movable frame, and the rolling elements 13a. The cross section including the first housing portion 212b / second housing portion 122b / rolling element 13b and the cross section including the first housing portion 212c / second housing portion 122c / rolling body 13c are the same as in FIG. Description is omitted. The outer diameter of the attraction back yoke 126a is set to be larger than the outer diameter of the second attraction magnet 125a in order to concentrate the magnetic flux lines on the rolling element 13a. By providing the suction back yoke 126a, the magnetic attraction force can be increased and the holding force of the rolling element 13a can be increased, and the magnetic leakage can be reduced and the adverse magnetic effect on other parts can be prevented. . For example, as schematically shown in FIG. 17 (the units of magnetic flux density and distance are omitted), magnetic leakage that occurs when the attracting back yoke is not provided and that has a peak at the center of the magnet is provided with the attracting back yoke. It can be seen that this can be remarkably prevented. In the present embodiment, the example in which the suction back yoke 126a is provided only on the movable frame 12 side is shown. However, in consideration of the magnetic influence on other portions, for example, as shown in FIG. 12, the fixed frame A21 In addition, the suction back yoke 215a may be provided, and, contrary to the present embodiment, the suction back yoke may be provided only on the fixed frame A21 side (not shown). Further, when it is not particularly necessary to prevent magnetic leakage, for example, as shown in FIG. 13, it is not necessary to provide a suction back yoke.

  The first attraction magnet 214a (and 214b, 214c) provided on the fixed frame A21 and the second attraction magnet 125a (and 125b, 125c) provided on the movable frame 12 may be the same size or different sizes. It may be. Further, the attraction magnet may be provided only on one of the fixed frame A21 and the movable frame 12, and only the attraction yoke may be provided on the other. For example, as shown in FIG. 14, the fixed frame A21 may be provided with the first suction magnet 214a and the suction back yoke 215a, and the movable frame 12 may be provided with only the suction yoke 129a. A configuration (not shown) in which two suction magnets 125a and a suction back yoke 126a are provided and only the suction yoke is provided in the fixed frame A21 may be employed. At this time, the suction back yoke 215a or the suction back yoke 126a may not be provided unless particularly required.

  The depth h1 of the first housing portion 212a and the depth h2 of the second housing portion 122a are shallower than 1/2 of the diameter d of the rolling element 13a, and there is a gap between the first housing portion 212a and the second housing portion 122a. It is set so that g1 is formed. The diameter d1 of the first housing part 212a and the diameter d2 of the second housing part 122a may be the same or different (for example, d1> d2), but the diameter d of the rolling element 13a and the maximum moving distance of the correction lens It is set to be larger than the sum of. By satisfying such a condition, when the rolling element 13a rolls (during camera shake correction), the rolling element 13a becomes the inner wall of the first accommodating part 212a of the fixed frame A21 and the second accommodating part 122a of the movable frame 12. Is prevented from coming into contact. Accordingly, there is no problem of hindering the position control when the correction lens is moved to the predetermined position. Since the other rolling elements 13b and 13c are also supported in the same manner as described above, the description thereof is omitted.

  In the present invention, the materials and dimensions of the first attracting magnets 214a, 214b, 214c, the second attracting magnets 125a, 125b, 125c and the attracting back yokes 126a, 126b, 126c, and the bottom surfaces of the first accommodating portions 212a, 212b, 212c The thickness t1 on the side and the thickness t2 (see FIG. 11) on the bottom surface side of the second accommodating portions 122a, 122b, 122c can permit smooth sliding of the rolling elements 13a, 13b, 13c, and in the optical axis direction. It is preferable to select such that a magnetic attractive force is obtained so that the rolling elements 13a, 13b, and 13c do not separate from the movable frame 12 and the fixed frame A21 even when a slight impact (acceleration of about several G) is applied to the rolling element 13a.

(3) Movable Magnet Type Voice Coil Motor Since the voice coil motor 3 that drives the correction lens 11 is a movable magnet type, it is possible to prevent the coil from being disconnected without routing the wiring by the movement of the motor. As shown in FIGS. 2 to 4, the movable magnet type voice coil motor 3 includes a coil portion 31 including flat coils 310a, 310b, and 310c fixed on the fixed member 2 side, and a fixed portion on the movable member 1 side. Permanent magnets 321a, 321b, 321c and magnetic circuit section 32 including yokes 320a, 320b, 320c. Each of the permanent magnets 321a, 321b, and 321c has a circumferential length larger than the radial width, matches the effective length in the circumferential direction of the flat coil, and is further magnetized in the optical axis direction. Are arranged so that magnetic poles of different polarities are aligned along the radial direction. By installing the permanent magnets 321a, 321b, and 321c in this manner, a radial thrust is generated in each voice coil motor 3 in a plane perpendicular to the optical axis, and by combining the thrusts, a perpendicular to the optical axis is generated. The correction lens 11 can be driven in an arbitrary direction on a plane. In this embodiment, the voice coil motor is configured by arranging three flat coils so as to circumscribe the reference circle at equal angular intervals (120 °). However, in the present invention, the angular interval is at least 90 °. It is preferable to arrange so as to be at an angle. 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 Are arranged at equal angular intervals (120 ° intervals) along the circumferential direction on one surface of the fixing member 2, that is, the surface facing the movable frame 12. 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 the present embodiment, as shown in FIG. 3, the Hall element is located at a position corresponding to the air core part of the coil on the surface opposite to the surface on which the flat coils 310a, 310b, 310c of the wiring board 22 are installed. 610a, 610b, and 610c are 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 (same as the number of flat coils) permanent magnets 321a, 321b, 321c provided at positions facing the flat coils 310a, 310b, 310c (three in this embodiment), 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 The boundary (magnetization neutral line) is oriented so as to face the tangential direction of a circle centered 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 tangential length Lm of the circle centered on the optical axis and the radial width of the flat coils 310a, 310b, and 310c in order to obtain a large thrust with a low drive current. It is preferable to set it larger than W1, and it is particularly preferable that Lm / W1 is in the range of 1.5 to 2.0.

  As permanent magnets 321a, 321b, and 321c, a single permanent magnet (block-shaped permanent magnet) is magnetized once, and a pair of magnetic poles (N pole and S pole) as shown in FIG. You may use what you have formed, or you may prepare a pair of block permanent magnets (single pole magnets) magnetized in the thickness direction and use these magnets fixed so that their magnetization directions are different good. 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 includes a 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 voice coil motor”) 40 is provided. The locking voice coil motor 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 coil 415 of the fixed frame B41. A magnetic shield plate 414 fixed to the opposite surface, a locking magnet 424 and a 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 magnet 424 with the locking back yoke 423 is driven, and the locking movable frame 42 is rotated in a predetermined direction to be fitted to the movable frame 12, and the correction is performed. The lens 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 a restricting member (not shown) such as a magnetic pin on the fixed frame B41. The wiring board 43 is preferably a flexible wiring board (FPC).

(5) Position detection means In the present invention, as shown in FIG. 10 (a), the position information of the movable frame 12 (not shown) including the correction lens 11 by the magnetic force of the magnetic circuit unit 32 of the voice coil motor 3 Position detecting means (lens position detecting unit 61) for detecting the above and 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. Since 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. 15, the maximum movement amount of the correction lens 11 (1 mm The magnetic flux density varies linearly in a narrower range.

  Here, for example, as shown in FIG. 10 (b), when the Hall element 610a is placed close to the surface of the permanent magnet 321a and placed on the first surface 221 side of the wiring board 22, the Hall element 610a is moved relative to the amount of movement of the movable frame. Output linearity decreases. On the other hand, as shown in FIG. 10 (a), by installing the Hall element 610a on the second surface 222 side of the wiring board 22, the distance between the Hall element 610a and the permanent magnet 321a is increased, and the magnetic flux density is increased. The non-linearity of the distribution is relaxed and the output voltage changes almost linearly as described above. Therefore, the position information of the movable part (permanent magnet) can be detected with high accuracy.

  Note that, as shown in FIG. 10 (c), when the flat coil 310a is installed on the wiring board 22 via the spacer 23, the Hall element 610a is provided on the first surface 221 side of the wiring board 22. However, the Hall element 610a can be disposed not at the inside of the flat coil 310a but at a position farther from the permanent magnet 321a than the flat coil 310a, and it becomes easy to ensure the linearity of the output voltage, and the magnetic field generated from the coil. Therefore, the position detection accuracy is improved.

  However, when the Hall element 610a is disposed on the second surface 222 side of the wiring board 22 as shown in FIG. 10 (a), and as shown in FIG. When the flat coil 310a is provided on the wiring board 22 through the spacer 23 provided on the first surface 221 side, the output voltage of the Hall element 610a decreases because the distance between the Hall element 610a and the permanent magnet 321a increases. Noise increases. Therefore, in order to obtain an output voltage with good linearity, a circuit configuration with measures such as increasing the power supply voltage, increasing the amplification degree of the output voltage, and removing noise by adding a noise filter It is preferable to do this. In order to obtain an output voltage having good linearity, the distance between the Hall element 610a and the permanent magnet 321a is, for example, an element made of GaAs as the Hall element and an NdFeB-based sintered magnet ((BH) max as the permanent magnet). = 45 to 50 MGOe) is preferably 1.3 to 2.0 mm.

  When the Hall element 610a is provided on the first surface 221 side of the wiring board 22, the terminals of the Hall element 610a and the coil terminal 311a are soldered to the wiring board 22, as shown in FIGS. 10 (b) and 10 (c). Although it is necessary to increase the inner diameter of the flat coil 310a in order to secure a space for attaching, as shown in FIG. 10 (a), by installing it on the second surface 222 side of the wiring board 22, A sufficient space for soldering the terminal of the element 610a and the coil terminal can be secured, and an increase in the size of the flat coil 310a can be prevented.

  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 III-V group compounds 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. A magnetic field detection element having a resolution of about 10 μT like the element is suitable.

  When the magnetic pole boundary 322 of the permanent magnet 321a (shown by a broken line in FIG. 10 (a)) 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 Nearly zero. When the permanent magnet 321a moves in the direction of arrow E or F in FIG. 10 (a), 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, 321c constituting each of the above voice coil motors, known permanent magnets (for example, rare earth magnets) can be used, but the flat coils 310a, 310b. In order to reduce the drive current (DC current) supplied to 310c and to obtain high thrust, use RFeB permanent magnets (R is at least one selected from rare earth elements including Y and must contain Nd). In particular, it is preferable to use an Nd—Fe—B anisotropic sintered magnet having a maximum energy product of 45 MGOe or more.

  The yokes 320a, 320b, and 320c are members that serve as magnetic paths, 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 (for example, the angular velocity of the camera body shake) detected by the camera shake amount detection unit 5 including the gyro sensor 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) and the shutter. And the mode switch information (shutter switch / mode switch 64) are sent to the correction amount calculation unit 65 together with the shooting mode information determined by the shooting mode determination unit 63, and are calculated by the correction amount calculation unit 65 based on these pieces of information. The camera shake correction amount (movement amount of the correction lens 11) is output to the voice coil motor drive circuit 7 as a voltage signal. By driving the correction lens 11 (see Fig. 2) according to this correction amount, the incident optical axis (Z 'axis direction in Fig. 1) that has 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 Voice Coil Motor FIG. 9 shows flat coils 310a, 310b, 310c provided on the wiring board 22, and 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 power is supplied to the flat coils 310a, 310b, and 310c of the movable magnet type voice coil motor 3, each magnetic circuit section 32 has a current perpendicular to the optical axis direction (XY plane) according to Fleming's left-hand rule. Accordingly, thrusts Fa1, Fb1, and Fc1 in the radial direction 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 size are applied to three flat coils, the magnitudes of the thrusts (Fa1, Fb1, Fc1) generated in each magnetic circuit part are the same, and their directions are radial directions, respectively. The thrust in the X direction (Fx) and the thrust in the Y direction (Fy) are zero, and the movable frame is in a stopped state.

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 changed to Ia = Ib = −I ₁ and the flat coil 310c. When the applied current Ic is Ic = I ₁ ), only the voice coil motor constituted by the flat coil 310c has a thrust direction opposite to that of other voice coil motors, and as a result, the thrust Fx in the X direction is
Fx = Fa1 · cosθ ₁ + Fb1 + Fc1 · cosθ ₂ ,
Y direction thrust Fy is
Fy ＝ Fa1 ・ sinθ ₁ ＋ Fc1 ・ sinθ ₂ ,
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 voice coil motor described in, for example, Japanese Patent Laid-Open No. 2007-86808, since the magnetization neutral line of the permanent magnet is in the radial direction, the flat coil must be formed in a rectangular shape (Japanese Patent Laid-Open No. 2007-86808). 2 (see FIG. 2 of 2007-86808), the area of the effective conductor portion is extremely smaller than that of the flat coil configured in the present invention (about 1/4 or less of the voice coil motor configured in the present invention). That is, in the present invention, by using a voice coil motor in which the magnetization neutral line of the permanent magnet is arranged in the tangential direction, the amount of magnetic flux contributing to thrust among the magnetic flux generated from the permanent magnet is increased as compared with the case of the prior art. Even if the current supplied to the coil is the same, a large thrust can be obtained. 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 it is possible to shoot at a slow shutter speed by reducing the aperture even in dark scenes. It has the advantage that it becomes possible.

(2) Position Detection Operation As shown in FIG. 18, inside the lens barrel 114, together with the correction voice coil motor 3 that drives the correction lens 11, Hall elements 610a, 610b, which detect the position of the correction lens 11. 610c is provided. 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, and 610c is located at the magnetic pole boundary (position where the polarity is reversed), the output voltage from the Hall elements 610a, 610b, and 610c is zero, but the correction lens 11 is provided. When the movable member 1 is driven and the relative positions of the Hall elements 610a, 610b, and 610c move in the X direction and / or the Y direction with respect to the magnetic circuit unit 32 provided on the movable member 1, the Hall element 610a is moved according to the amount of movement. , 610b, 610c change the magnetic flux density and output the output voltage as a position signal in proportion to the magnetic flux density.

  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. A current proportional to the difference between the coil position command signal (a signal indicating the position at which the correction lens 11 should be moved in accordance with the amount of camera shake correction) is supplied to the driving coil. When the difference between the output from the signal processing circuit and the coil position command signal disappears, the drive current to the coil stops and the thrust of the correcting voice coil motor becomes zero.

[0004]
The present inventors have found that the moving range of the movable member can be kept within an appropriate range by the supporting means configured so that the force acts.
[0012]
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 that is disposed so as to face the fixed member when viewed from the optical axis direction and is made of a non-magnetic material that supports 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 oblong flat air-core coils provided on the fixed member, and a plurality of magnetic circuit portions provided on the movable member at positions corresponding to the air-core coils, A movable magnet type voice coil motor that moves a movable member in a plane orthogonal to the optical axis of the correction lens;
A camera shake correction unit comprising control means for controlling the moving direction and moving amount of the voice coil motor,
The air-core coil is arranged on a circumference centered on the optical axis in a plane orthogonal to the optical axis direction of the fixing member so that the longitudinal direction coincides with the tangential direction,
The magnetic circuit section is fixedly provided so that a flat plate yoke made of a ferromagnetic material fixed to the movable member, and a pair of magnetic poles fixed to the yoke and opposite in polarity to the air-core coils are opposed to each other. Including a plurality of flat permanent magnets,
The support means includes a plurality of permanent magnets respectively provided on the movable member and the fixed member so that a magnetic attractive force acts between the movable member and the fixed member, and a plurality of permanent magnets provided on the movable member. A plurality of rolling elements made of a ferromagnetic material sandwiched between a permanent magnet and a plurality of permanent magnets provided on the fixed member, and a part of the rolling elements provided at positions corresponding to the permanent magnets The rolling element is in contact with the bottom surface of the movable member and the fixed member.
[0013]
It is preferable that a suction back yoke is provided on the side opposite to the side facing the fixed member of the plurality of permanent magnets provided on the movable member.

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 oblong flat air-core coils provided on the fixed member, and a plurality of magnetic circuit portions provided on the movable member at positions corresponding to the air-core coils, A movable magnet type voice coil motor that moves a movable member in a plane orthogonal to the optical axis of the correction lens;
A camera shake correction unit comprising control means for controlling the moving direction and moving amount of the voice coil motor,
The air-core coil is arranged on a circumference centered on the optical axis in a plane orthogonal to the optical axis direction of the fixing member so that the longitudinal direction coincides with the tangential direction,
The magnetic circuit section is fixedly provided so that a flat plate yoke made of a ferromagnetic material fixed to the movable member, and a pair of magnetic poles fixed to the yoke and opposite in polarity to the air-core coils are opposed to each other. Including a plurality of flat permanent magnets,
The support means includes a plurality of permanent magnets respectively provided on the movable member and the fixed member so that a magnetic attractive force acts between the movable member and the fixed member, and a plurality of permanent magnets provided on the movable member. A plurality of rolling elements made of a ferromagnetic material sandwiched between a permanent magnet and a plurality of permanent magnets provided on the fixed member, and a part of the rolling elements provided at positions corresponding to the permanent magnets A camera shake correction unit comprising: an accommodating portion for accommodating.   2. The camera shake correction unit according to claim 1, wherein a suction back yoke is provided on a side opposite to the side facing the fixed member of the plurality of permanent magnets provided on the movable member. Correction unit.   3. The camera shake correction unit according to claim 1, wherein a suction back yoke is provided on a side opposite to the side facing the movable member of the plurality of permanent magnets provided on the fixed member. A camera shake correction unit.   4. The camera shake correction unit according to claim 2, wherein an outer diameter of the suction back yoke is larger than an outer diameter of the corresponding plurality of permanent magnets.   5. The camera shake correction unit according to claim 1, wherein the plate-like permanent magnet forming the magnetic circuit unit has a magnetic neutral line tangential to a circumference around the optical axis. An image stabilization unit that is arranged so as to coincide with

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