JP2014089357A - Camera shake correction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a camera shake correction device capable of moving a correction lens in a wide range while ensuring high positioning accuracy.SOLUTION: The camera shake correction device comprises: a fixed frame 3 fixed in a lens barrel; a shift frame 2 supported so as to face the fixed frame 3 and be movable in a plane perpendicular to the optical axis, and holding the correction lens; first to third voice coil motors (VCMs) 5a, 5b each having a magnet member arranged on the shift frame 2, an air-core coil arranged on the fixed frame 3, and a counter yoke arranged on a surface opposite to the air-core coil; and first and second potion detection means having magnetic field detection elements arranged between the air-core coils on the fixed frame 3, and detection magnets arranged on the shift frame 2. The first and second position detection means are arranged so as to detect positions in directions perpendicular to each other in a plane perpendicular to the optical axis. As viewed from the optical axis direction, the counter yokes constituting the first and second VCMs 5a, 5b each have a circular shape, and have an area smaller than that of the counter yoke constituting the third VCM.

Description

  The present invention relates to a lens shift type camera shake correction apparatus in which a correction lens is moved by a voice coil motor in order to prevent shake of a subject image due to camera shake.

  In imaging optical devices such as digital cameras, it is common to mount a camera shake correction device inside the device in order to take high-quality photos, and this camera shake correction is usually under preparation for shooting (release button). Halfway pressing) and during shooting. For example, in a digital single-lens reflex camera, it is possible to take a high-quality photograph even with a longer focusing lens and a higher magnification zoom, and to enable the camera shake prevention function to be seen while observing the subject on the viewfinder. In addition, in the interchangeable lens, a gyro sensor that detects rotational shake, and in response to the output of the gyro sensor, a part of a plurality of lens groups constituting the photographing optical system (correction lenses) are in a plane orthogonal to the optical axis. A camera shake correction device equipped with a voice coil motor (hereinafter referred to as “VCM”) that shifts at the same time is incorporated. In this camera shake correction device, there has been proposed an actuator having a simple mechanism that omits the guide mechanism by translating the correction lens on a plane orthogonal to the optical axis and further rotating it.

  Japanese Patent Laid-Open No. 2011-180519 (Patent Document 1) includes a fixed part (12), a movable part (14) to which an image blur prevention lens is attached, and a movable part support means (18) for supporting the movable part. And a driving magnet (22a, 22b, 22c) and a driving coil (20a, 20b, 20c) arranged opposite thereto, and generates a driving force in a generally radial direction of a circle centered on the optical axis A. First, second and third drive means, position detection means (24a, 24b, 24c) for detecting displacement of the movable part relative to the fixed part, and each drive means based on the displacement detected by the position detection means Describes a lens unit including an anti-vibration actuator having a control unit (36) for controlling a current flowing through the driving coil and moving a movable unit to a predetermined position.

  Japanese Patent Laid-Open No. 2010-197519 (Patent Document 2) includes a movable member that holds a correction lens and a base portion of a unit in order to expand a region in which the linearity of the Hall element output can be secured without reducing the driving force. A base member that supports the movable member with respect to the base member so as to be able to translate and rotate on a plane substantially orthogonal to the optical axis of the correction lens, a position detection unit that detects the position of the correction lens, and a movable member Three driving means for moving the member in a direction substantially perpendicular to the optical axis, and the driving means is at least a coil mounted on a substrate fixed to the base member, and a movable member at a position facing the coil. An optical correction unit is described in which the position detection means is provided on the surface of the substrate on which the coil is not mounted.

  However, in the actuators described in Patent Document 1 and Patent Document 2, since the position sensor is disposed close to the drive coil, when a drive current is supplied to the drive coil, the actuator is affected by the magnetic field generated by the drive coil. As a result, the sensor output is disturbed, resulting in a problem that high positioning accuracy cannot be obtained.

JP 2011-180519 JP JP 2010-197519

  Accordingly, an object of the present invention is to provide a camera shake correction apparatus that can move a correction lens within a predetermined range while ensuring high positioning accuracy.

  As a result of diligent research in view of the above object, the inventors of the present invention have arranged a position sensor, which has been disposed in the vicinity of the drive coil, at a position spaced apart from the drive coil, and a counter yoke that constitutes a voice coil motor. The present inventors have found that a camera shake correction apparatus having a high positioning accuracy and capable of detecting a position with high accuracy can be obtained by making the shape of the lens circular.

That is, the camera shake correction apparatus of the present invention is
A fixed frame fixed in the lens barrel;
A shift frame holding a correction lens, which is supported movably in a plane facing the fixed frame and orthogonal to the optical axis;
A magnet member arranged on the shift frame, an air core coil opposed to the magnet member and arranged on the fixed frame, and a counter yoke arranged on a surface of the fixed frame opposite to the air core coil And the first to third voice coil motors arranged along the circumferential direction to move the shift frame in a plane orthogonal to the optical axis,
1st and 2nd position detection means which has a magnetic field detection element installed between the air core coils of the fixed frame, and a detection magnet arranged in the shift frame opposite to the magnetic field detection element. ,
The first and second position detection means are arranged so as to perform position detection in a direction orthogonal to the first direction and the first direction, respectively, in a plane orthogonal to the optical axis,
When viewed from the optical axis direction, the opposed yokes constituting the second and third voice coil motors are circular and have a smaller area than the opposed yokes constituting the first voice coil motor. To do.

  The magnetic field detection element is preferably a Hall element, and the detection magnet is preferably magnetized in the optical axis direction.

  The opposing yoke that constitutes the first voice coil motor preferably has a shape that is longer in the circumferential direction than in the radial direction when viewed from the optical axis direction.

  It is preferable that the fixed frame has a positioning protrusion inserted into the air core of the coil.

  In the camera shake correction device of the present invention, the magnetic field detection element is affected by the magnetic field generated when the air core coil is energized by providing the magnetic field detection element at a position separated from the air core coil when viewed from the optical axis direction. Therefore, the position of the correction lens can be detected with high accuracy. Therefore, it is not necessary to correct the position detection signal output from the magnetic field detection element.

  By providing the magnetic field detection element at a position away from the air-core coil when viewed from the optical axis direction, a circular one can be used for the opposing yoke that constitutes the voice coil motor. As a result, positioning accuracy by the voice coil motor Will improve dramatically.

  Since the positioning projection of the fixed frame can be inserted inside the air-core coil, it becomes possible to install the air-core coil at a predetermined position, and it is possible to reduce the man-hours for assembling the voice coil motor. Accordingly, the manufacturing cost of the camera shake correction device can be reduced.

It is a schematic diagram which shows an example of the system configuration | structure of the digital camera by which the camera-shake correction apparatus of this invention is mounted. It is an external appearance perspective view which shows the camera-shake correction apparatus of this invention. It is AA sectional drawing of FIG. FIG. 3 is an exploded perspective view of FIG. 2. It is the disassembled perspective view which looked at FIG. 2 from the back side. It is the perspective view which looked at the shift frame of FIG. 2 from the (a) C direction and (b) the back side. It is the perspective view which looked at the fixed frame of FIG. 2 from (a) C direction and (b) the back side. It is a top view which shows typically arrangement | positioning of the voice coil motor and position detection means which comprise the camera-shake correction apparatus of this invention. It is a schematic cross section which shows the position detection means which comprises the camera-shake correction apparatus of this invention. FIGS. 9A and 9B are an enlarged view of a third voice coil motor 5c portion shown in FIG. 8 and FIG. FIGS. 9A and 9B are an enlarged view of a first voice coil motor 5a portion shown in FIG. 8, and FIG. It is a graph which shows the magnetic flux density of the normal ray direction obtained when a Hall element is moved to a X direction.

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

[1] Camera As shown in FIG. 1, the digital single-lens reflex camera 10 connects an optical image of a subject with a body 11 having a solid-state image sensor 13 (for example, CCD or CMOS) via an optical filter (not shown). And a lens barrel 12 having a plurality of lens groups 14 to be imaged. The lens group 14 includes, for example, a focus lens group, a first lens group G1 having a positive refractive power, a large movement for zooming, a second lens group G2 having a negative refractive power, A positive lens including a correction lens 15 (for example, a cemented lens) that corrects the image point movement that has occurred and constitutes a third group lens group G3 having a positive refractive power and a relay system and is provided with the image stabilization unit 1 is provided. And an inner focus type four-group zoom lens having a fourth lens group G4 having a refractive power of 5 mm.

  Since the camera shake correction unit 1 of the present invention employs a lens shift method as a camera shake correction unit, the camera shake prevention function can be visually recognized 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 (or a lens group) that satisfies these conditions may be selected as the correction lens. In the example shown in FIG. 1, the position detection means 6a, 6b are included in the correction lens 15 included in the fourth lens group G4. A camera shake correction unit 1 including

  In the lens barrel 12, for example, two gyro sensors 16a and 16b are provided in order to detect a vertical camera shake amount (pitch shake) and a horizontal camera shake amount (yaw shake). The camera shake amount (angular acceleration) detected by the gyro sensors 16a and 16b is input to the control unit 17, and an excessive signal generated during panning is removed by a high-pass filter and a low-pass filter (both not shown). Thereafter, it is output as a target position signal corresponding to the amount of camera shake (a signal indicating the position where the correction lens 15 should be moved according to the amount of camera shake correction). Phase compensation is performed on the difference signal (position command signal) between the target position signal and the position signal of the correction lens 15 (the signal indicating the position of the correction lens 15 detected by the position detection means 6a and 6b), and a drive circuit (for example, PWM) Circuit). The analog converted drive signal is supplied to the drive coil of the voice coil motor 5 incorporated in the camera shake correction unit 1 to drive the correction lens and control its position. Since the frequency band of camera shake is a narrow band of about 1 to 10 Hz, an image with sufficiently small camera shake can be obtained by normal feedback control (PID control). In order to prevent the correction optical system from falling down, the camera shake correction device 1 is preferably configured such that the voice coil motor, which is the drive unit of the camera shake correction unit, is positioned near the center of gravity of the correction optical system.

[2] Image stabilization unit
(1) Overall Configuration As shown in FIGS. 2 to 5, the camera shake correction apparatus 1 supports a shift frame 2 that holds a correction lens 15 and the shift frame 2 in a lens barrel 12 (see FIG. 1). And a voice board motor (hereinafter referred to as “VCM”) that drives the shift frame 2 in a plane orthogonal to the optical axis Z. ) 5a, 5b, 5c and a plurality of rolling elements (hereinafter referred to as “steel balls”) 4a, 4b, 4c made of ferromagnetic material interposed between the shift frame 2 and the fixed frame 3. It has. The shift frame 2 includes a circuit board 7 such as a flexible printed circuit board (FPC) on which a signal processing circuit (feedback amplifier circuit) including an operational amplifier 9 is mounted, and an undesired movement in the Z-axis direction by a presser ring 83. Is regulated.

  By inserting three steel balls 4a, 4b, and 4c between the shift frame 2 and the fixed frame 3 in the Z-axis direction, the shift frame 2 is in relation to the fixed frame 3 with respect to the Z-axis. Therefore, the sliding (friction) resistance can be reduced, and minute angular shake can be corrected. Moreover, since the steel balls are magnetically attracted and held in the Z-axis direction, undesired movement of the steel balls can be suppressed.

  The camera shake correction apparatus 1 can include a locking mechanism unit that keeps the correction lens stationary at a position that coincides with the optical axis during non-imaging. The locking mechanism portion includes a lock lever 82 that holds the shift frame 2 in the optical axis direction, and a lock lever presser 81 that is fixed to the fixed frame 2, and the camera shake correction OFF state (the camera shake correction mechanism is not operated). In the state), the correction lens is held in a neutral state (coaxial with the optical axis) without being energized, and in the state where the camera shake correction is on (state in which camera shake correction is possible), an arbitrary plane within the plane orthogonal to the optical axis Z To move in the direction. The details of each part of the camera shake correction apparatus 1 are as follows.

(2) Shift frame As shown in FIGS. 6 (a) and 6 (b), the shift frame 2 is made of a nonmagnetic material such as engineering plastic (e.g., PC), and has a ring portion 21 that holds the correction lens 15. It is a substantially annular member having a flange portion 22 formed on its end face. On the surface of the flange portion 22, magnet holding portions 23a, 23b, 23c are formed at equal angular intervals (120 °) along the circumferential direction, and in the middle of each magnet holding portion 23a, 23b, 23c, A housing groove 24a, 24b, 24c for receiving a part of the steel ball is formed (see FIG. 6B).

  A lock lever 82 having lock pins 821a, 821b, and 821c is engaged with the shift frame 2 with a presser ring 83 interposed therebetween. That is, by rotating the protrusion 820 of the lock lever 82 in a predetermined direction (for example, counterclockwise), the lock pins 821a, 821b, and 821c are formed on the surfaces of the magnet holding portions 23a, 23b, and 23c of the shift frame 2. The semicircular arc-shaped holding holes 230a, 230b, and 230c are fitted. In the shift frame 2, protrusions 25 a, 25 b, 25 c provided on the surface of the flange portion 22 are inserted through the guide holes 831 a, 831 b, 831 c of the presser ring 83 and can be rotated in the circumferential direction. The shift frame 2 has an extending portion 26 having a protruding portion 260 formed on the side surface.

(3) Fixed frame As shown in FIGS. 7 (a) and 7 (b), the fixed frame 3 is a substantially annular member made of a non-magnetic material such as engineering plastic (for example, PC), and the shift frame It is arranged opposite to 2. Coil holding grooves 31a, 31b, 31c for fixing the air core coils 53a, 53b, 53c constituting the VCMs 5a, 5b, 5c are formed in the fixed frame 3, and further, the air core coils 53a, 53b, 53c Positioning protrusions 32a, 32b, and 32c inserted into the air core are formed.

(4) VCM
As described above, the shift frame 2 and the fixed frame 3 include first to third VCMs 5a, 5b, 5c (first VCM 5a, 1C) for driving the correction lens in an arbitrary direction within a plane orthogonal to the optical axis. The members constituting the second VCM 5b and the third VCM 5c) are arranged at equiangular intervals (120 °) with the optical axis Z as the center when viewed from the optical axis Z direction. VCMs 5a, 5b, 5c are back yokes 51a, 51b, 51c (for example, silicon steel plates) fixed to magnet holding portions 23a, 23b, 23c of shift frame 2 and permanent magnets 52a, 52b, 52c (for example, rare earth, iron, (A boron-based sintered magnet) including magnetic members 50a, 50b, 50c and air-core coils 53a, 53b, 53c provided on the fixed frame 3, the air-core coils 53a, 53b, 53c are in the optical axis direction. The magnet members 50a, 50b, 50c generate a magnetic field interlinking with the air-core coils 53a, 53b, 53c.

  The first VCM 5a, the second VCM 5b, and the third VCM 5c are selectively driven by one or more of them, thereby causing vertical deflection (pitching) and / or horizontal deflection (yawing). Is not necessarily an equiangular interval, for example, the angle between the first VCM 5a and the second VCM 5b is 135 °, and the second VCM 5b and the third VCM 5c The angle formed may be 135 °, and the angle formed between the third VCM 5c and the first VCM 5a may be 90 °. However, when the lens barrel 12 is mounted on the camera, the VCM (for example, the third VCM5c) that generates thrust in the vertical direction (the direction opposite to gravity) is arranged at the top of the lens barrel. Is preferred. In addition, by making the opposing yoke 54c constituting the third VCM 5c larger than the opposing yokes 54a and 54b, when the third VCM 5c is arranged at the top of the lens barrel, it is opposite to gravity. The direction propulsive force (thrust Fc) can be increased, and the shift frame 2 having the correction lens 15 can be easily moved against gravity.

  Each of the permanent magnets 52a, 52b, 52c is composed of a pair of permanent magnets magnetized in the thickness direction (direction parallel to the optical axis), and a pair of magnetic poles of different polarities are arranged along the radial direction (magnetic pole boundary line 520a, 520b, 520c are oriented in the tangential direction of the circumference around the optical axis), that is, so that there is a pair of magnetic poles having different polarities on the surface facing the air core coils 53a, 53b, 53c. It is installed (see FIG. 8). Each permanent magnet 52a, 52b, 52c has a circumferential length greater than the radial width and an effective length (effective conductor portion) of the air-core coils 53a, 53b, 53c in the circumferential direction. Installed to match.

  As shown in FIG. 7 (b), on the surface of the fixed frame 3 opposite to the air core coils 53a, 53b, 53c, opposed yokes 54a, 54b and 54c (for example, silicon steel plates) are fixed, and the opposing yokes 54a and 54b are circular when viewed from the optical axis direction and have a smaller area than the opposing yoke 54c. The counter yoke 54c may have any shape as long as it has a larger area than the counter yokes 54a and 54b, but is preferably circular or square, and the radial length is longer than the radial length. More preferably, the rectangular shape is short.

  As shown in FIG. 8, the VCMs 5a, 5b and 5c have magnetic fluxes generated from the permanent magnets 52a, 52b and 52c interlinked with the effective conductor portions (straight portions of the coils) of the air-core coils 53a, 53b and 53c. Each generates thrust in the radial direction. That is, when power is supplied to the flat coils 53a, 53b, and 53c of the VCMs 5a, 5b, and 5c, the thrusts Fa and Fb in the radial direction in the plane perpendicular to the optical axis direction are applied to the magnet members 50a, 50b, and 50c according to Fleming's left-hand rule. And Fc occur. Since the thrust acting on the entire shift frame 2 is a combination of the VCM thrusts Fa, Fb and Fc, by adjusting the direction and magnitude of the current supplied to each VCM 5a, 5b, 5c, it is perpendicular to the optical axis. It is possible to move the shift frame 2 in an arbitrary direction on a plane.

Here, the thrusts Fx and Fy in the X direction and Y direction acting on the shift frame 2 having the correction lens are formed by the thrusts Fa, Fb and Fc generated by the VCM, and the X axis and Fa as shown in FIG. From the angle θ ₁ and the angle θ ₂ formed by the X axis and Fb,
Fx = Fa × cos (θ ₁ ) −Fb × cos (θ ₂ )
Fy ＝ Fa × sin (θ ₁ ) + Fb × sin (θ ₂ ) −Fc
It is represented by That is, the correcting lens can be moved in the X direction and the Y direction by combining the thrusts Fa, Fb, and Fc of each VCM.

  FIG. 10 (a) is a schematic diagram showing the third VCM 5c portion shown in FIG. 8 in an enlarged manner, and FIG. 10 (b) is a BB cross-sectional view thereof. The opposing yoke 54c is, for example, a rectangle having approximately half the area of the permanent magnet 52c, and is preferably disposed so as to face the outer half (opposite side of the optical axis center) of the permanent magnet 52c. By arranging in this way, as shown in FIG. 10 (b), the magnetic flux flowing out from the N pole of the permanent magnet 54c is guided toward the S pole through the opposing yoke 54c. The generated magnetic flux is easily concentrated on the outer portion of the VCM 5c, and the thrust Fc for lifting the shift frame 2 upward increases. The area of the opposing yoke 54c viewed from the optical axis direction is preferably 30 to 70% of the area of the permanent magnet 52c. The radial length when the opposing yoke 54c is viewed from the optical axis direction is preferably 40 to 60% of the radial length of the permanent magnet 52c, and the circumferential length is greater than the circumferential length of the permanent magnet 52c. It is preferably short and 80% or more of the length.

  FIG. 11 (a) is a schematic diagram showing the first VCM 5a portion shown in FIG. 8 in an enlarged manner, and FIG. 11 (b) is a CC cross-sectional view thereof. Since the second VCM 5b is the same as the first VCM 5a, the illustration is omitted. The opposing yokes 54a and 54b are provided so as to be positioned substantially at the centers of the permanent magnets 52a and 52b and the air-core coils 53a and 53b constituting the VCMs 5a and 5b. By making the opposing yoke 54a a circular with a relatively small size, the magnetic flux flowing out from the N pole is induced toward the S pole via the opposing yoke 54a, as shown in FIG. 11 (b). Can be concentrated on a small area of the opposing yoke 54a, and the fixed frame 3 can be easily centered about the axis (the same applies to the opposing yoke 54b). The area of the opposing yokes 54a and 54b viewed from the axial direction is preferably 1 to 7% and more preferably 2 to 5% of the area of the permanent magnets 52a and 52b.

(4) Position detection means In the present invention, the position information of the correction lens is detected by the magnetic force of the permanent magnet and the detection signal is output as a voltage. The magnetic field detection elements 61a and 61b installed in the fixed frame 3 are shifted. Position detecting means 6a and 6b comprising detection magnets 62a and 62b arranged in the frame 2 are provided between the air core coils of the fixed frame. In the example shown in FIG. 8, a detection magnet 62a provided on a yoke 63a (not shown) is arranged between a magnet member 50a and a magnet member 50c constituting the VCM arranged in the shift frame 2, and the magnet member A detection magnet 62b provided on the yoke 63b is disposed between the magnetic member 50c and the magnetic member 50c (see FIG. 9). The detection magnet 62a is composed of a pair of permanent magnets magnetized in the optical axis direction, arranged so that a pair of magnetic poles are arranged along the Y-axis direction, and the detection magnet 62b is a pair magnetized in the optical axis direction. The permanent magnets are arranged such that a pair of magnetic poles are arranged along the X-axis direction. That is, the detection magnet 62a and the detection magnet 62b are arranged in such directions that the magnetic pole boundary line 620a and the magnetic pole boundary line 620b are orthogonal to the Y axis and the X axis, respectively, and are orthogonal to each other by the position detection means 6a and 6b. Directional position information can be detected.

  The two magnetic field detection elements 61a and 61b (for example, the hall elements 611a and 611b) are arranged on the surface of the fixed frame 3 on the side where the air core coils 53a, 53b, and 53c are attached. It is disposed at a position spaced from 53c (between the air-core coil and the air-core coil). In the conventional camera shake correction device, the magnetic field detecting means and the VCM are arranged at the same position, and the magnetic field detecting element is provided in the air core coil of the fixed frame. Under the influence of the magnetic field generated by the core coil, the output from the magnetic field detecting element is disturbed and positioning cannot be performed with high accuracy. In addition, when the circular opposing yokes 54a and 54b are used as described above, the magnetic flux from the permanent magnets 52a and 52b is concentrated on the opposing yokes 54a and 54b, so that the influence of the magnetic flux from the permanent magnets 52a and 52b becomes larger. Positioning accuracy further decreased. In contrast, by arranging the position detection elements 61a and 61b between the air core coils of the fixed frame, the magnetic field detection elements 61a and 61b are generated from the air core coils 53a, 53b and 53c, and the magnetic field constantly changing. And the influence of the magnetic flux from the permanent magnets 52a and 52b, the position of the correction lens can be accurately detected.

  Hall elements 611a and 611b are used as the magnetic field detection elements 61a and 61b, and the Hall element 611a and the Hall element 611b are respectively arranged near the boundary between the north pole and the south pole (the magnetic pole boundary line 620a or the magnetic pole boundary line 620b). When measuring the magnetic field in the normal direction (Z-axis direction) when moved in the direction and the Y-axis direction, as shown in FIG. 12, the magnetic flux density distribution that changes almost monotonically from the N-pole side to the S-pole side Is obtained. At this time, the gap g between the Hall elements 611a and 611b and the detection magnets 62a and 62b is set such that the magnetic flux density and the gap are such that the region in which the magnetic flux linearly changes is wider than the maximum movement amount (about 1 mm) of the correction lens. It is necessary to set an optimal value. If the gap g between the Hall elements 611a and 611b and the detection magnets 62a and 62b (for example, rare earth / iron / boron sintered magnet) is widened (for example, 1.3 mm or more), the nonlinearity of the magnetic flux density distribution is relaxed. Since the output voltage changes linearly, the position information of the movable part (correction lens) can be detected with high accuracy. However, if the gap between the detection magnets 62a and 62b and the Hall elements 611a and 611b is too wide, the output voltage of the Hall elements 611a and 611b is lowered. Therefore, the gap is preferably 2 mm or less. When the output voltage drops due to the widening of the gap g, in order to secure the same level of sensitivity as before, the amplification of the output voltage is increased and a noise filter is added so that noise can be removed. It is preferable to adopt a circuit configuration.

  In the position detection means 6b, as shown in FIG. 9, if the position in the X-axis direction of the boundary 620b of the magnetic pole of the detection magnet 62b overlaps the position in the X-axis direction at the center (origin Sp) of the Hall element 611b, Since the component in the Z-axis direction (optical axis direction) of the magnetic field of the magnet 62b is zero, the output voltage of the Hall element 611b is almost zero. When the detection magnet 62b moves in the X-axis direction (arrow X direction) from the origin Sp, a voltage proportional to the moving distance is output from the Hall element 611b. Although illustration is omitted, similarly, when the detection magnet 62a moves in the Y-axis direction from the origin, a voltage proportional to the movement distance is output from the Hall element 611a.

  Based on these output voltages, the movement distances of the Hall elements 611a and 611b are calculated to determine the position of the correction lens 15, and the drive current is controlled by comparing the position signal of the correction lens 15 with the target position signal. be able to. That is, the position information detected by the Hall elements 611a and 611b is amplified to a predetermined magnification by the position detection circuit and output as a position signal, while the angular velocity information from the gyro sensor is processed by the angular velocity detection circuit and output as a target position signal. Then, the difference between these position signals and the target position signal is calculated by the control circuit and output as a position command signal, and a drive current corresponding to the position command signal is supplied from the drive circuit to the coil.

  In the present invention, as the magnetic field detection element, 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 as described above. The output voltage of the Hall element depends on the electron mobility and Hall coefficient of the material. As the magnetic field detection element, a Hall element formed of an N-type semiconductor thin film (thickness of several μm) made of a III-V group compound such as GaAs, InSb, or InAs is preferably used. In particular, the position detecting means used in the present invention uses a Hall element formed of GaAs having a small Hall coefficient temperature coefficient (about −0.06% / ° C.) in order to enable highly accurate position control. Is preferred.

  In addition, as a Hall element other than the compound system, a Hall element made of Si can be used. The Si Hall element can be used as a Hall IC integrated with a signal processing circuit such as an operational amplifier, but in this case, since the sensitivity of the Hall element is low, the offset voltage of the Hall element and the operational amplifier is reduced as much as possible, 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, in consideration of cost and the like, the Hall element is preferable.

  In the present invention, in order to drive the Hall element (4 terminals) and obtain an output voltage proportional to the magnetic flux density, a drive circuit is connected to the input side terminal of the Hall element and a differential is connected to the output side terminal of the Hall element. A circuit configuration in which an amplifier circuit is connected can be obtained. In general, Hall elements can be driven at a constant current or voltage. However, when GaAs Hall elements are used, driving at a constant voltage deteriorates the temperature characteristics (approximately -0.3% / ° C). It is preferable to do so. In the present invention, for example, an operational amplifier having a non-inverting input terminal connected to a power supply (Vc = reference voltage) and a constant current driving circuit made of a current limiting resistor are connected to the input side of the Hall element a to control current. It can be driven by a constant current operation where Ic = Vc / R1.

  In Hall elements (the equivalent circuit is represented by a bridge circuit consisting of four elements), the resistance value of each element varies due to manufacturing reasons, etc. (Unbalanced voltage) may be output. In order to cancel such an offset voltage, it is preferable to add an offset adjustment circuit (for example, a variable resistor) to the signal processing circuit.

1: Shake correction device,
2: Shift frame,
21: Ring part
22: Flange
23a, 23b, 23c: Magnet holder
230a, 230b, 230c: Holding holes
24a, 24b, 24c: receiving groove
25a, 25b, 25c: protrusion
26: Extension part
260: Protruding part
3: Fixed frame,
31a, 31b, 31c: Coil holding groove
32a, 32b, 32c: Projection for positioning
4a, 4b, 4c: Rolling elements (steel balls)
5a, 5b, 5c: VCM,
50a, 50b, 50c: Magnet members
51a, 51b, 51c: Back yoke,
52a, 52b, 52c: Permanent magnet,
520a, 520b, 520c: Magnetic pole boundary line
53a, 53b, 53c: Air-core coil,
54a, 54b, 54c: Opposing yoke
6a, 6b: Position detection means
61a, 61b: Magnetic field detector
611a, 611b: Hall element,
62a, 62b: Detection magnet 7: Circuit board
81: Lock lever presser
82: Lock lever
820: Protruding part
821a, 821b, 821c: Lock pin
83: Presser ring
10: Camera,
11: Body,
12: Tube,
13: Image sensor,
14: Lens group
15: Correction lens
16a, 16b: Gyro sensor
17: Control unit

Claims (4)

A fixed frame fixed in the lens barrel;
A shift frame holding a correction lens, which is supported movably in a plane facing the fixed frame and orthogonal to the optical axis;
A magnet member arranged on the shift frame, an air core coil opposed to the magnet member and arranged on the fixed frame, and a counter yoke arranged on a surface of the fixed frame opposite to the air core coil And the first to third voice coil motors arranged along the circumferential direction to move the shift frame in a plane orthogonal to the optical axis,
1st and 2nd position detection means which has a magnetic field detection element installed between the air core coils of the fixed frame, and a detection magnet arranged in the shift frame opposite to the magnetic field detection element. ,
The first and second position detection means are arranged so as to perform position detection in a direction orthogonal to the first direction and the first direction, respectively, in a plane orthogonal to the optical axis,
When viewed from the optical axis direction, the opposed yokes constituting the second and third voice coil motors are circular and have a smaller area than the opposed yokes constituting the first voice coil motor. Camera shake correction device.   2. The camera shake correction apparatus according to claim 1, wherein the magnetic field detection element is a Hall element, and the detection magnet is magnetized in the optical axis direction.   The camera shake correction device according to claim 1 or 2, wherein the opposing yoke constituting the first voice coil motor has a shape whose circumferential direction is longer than the radial direction when viewed from the optical axis direction. A camera shake correction device.   4. The camera shake correction device according to claim 1, wherein the fixed frame includes a positioning protrusion that is inserted into an air core portion of the coil.