Image blur prevention actuator and lens unit and camera equipped therewith

An actuator for moving an imaging lens to prevent blurring of an image includes a fixed portion; a movable portion attached to the imaging lens; a plurality of spherical bodies sandwiched between the movable portion and the fixed portion, supporting the movable portion; a drive means; fixed portion drop prevention walls and movable portion drop prevention walls, erected so as to respectively surround each of the spherical bodies and prevent the spherical bodies from dropping; fixed portion contact walls and moving portion contact walls formed contiguously with these drop prevention walls such that when the movable portion is moved to a predetermined locking position, the spherical bodies contact it; and a controller for moving the movable portion to a locking position by rotating the movable portion around the optical axis, thereby positioning each of the spherical bodies.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an actuator and a lens unit and camera equipped therewith, and more particularly to an actuator and a lens unit and camera equipped therewith in which imaging lenses are moved within a plane perpendicular to the optical axis thereof to prevent image blurring.

2. Description of Related Art Including Information Disclosed Under 37 CFR §§1.97 and 1.98

JP 2001-290184 (Patent Document 1) describes an observation device. In this observation device a movable piece, to which a blur compensation lens is attached, is supported by three balls (spherical bodies), and image blurring is compensated by moving the blur compensation lens within a plane perpendicular to the optical axis. The balls supporting the movable piece are disposed inside a square limiting portion (walls). Furthermore, the observation device translationally moves the movable piece up to a maximum degree of movement, causing each ball to contact a limiting portion, after which a reset operation is performed to return the movable piece by a predetermined distance. Each ball is positioned by this reset operation within a certain range which is returned by a predetermined distance from the position at which contact was made with a limiting piece.

JP 2006-119249 (Patent Document 2) describes an actuator used to prevent image blurring. In this actuator, a moving frame is caused to rotate around an optical axis up to a locking position, and the moving frame is locked by engagement between a protuberance formed on the periphery of the moving frame and a cam-shaped piece disposed corresponding thereto.

The actuator described in JP 2006-119249 has the advantage that the moving frame can be locked without providing a special actuator for the purpose of locking the moving frame.Patent Document 1: JP 2001-290184Patent Document 2: JP 2006-119249

3. Problems to Be Solved by the Invention

However, in the observation device described in JP 2001-290184, the movable piece to which the blur compensation lens is attached is caused to move translationally to the maximum degree of movement during the reset operation, causing the problem that images formed during the reset operation are significantly blurred.

A further problem arises because in the observation device a special reset operation must be executed in order to position the balls (spherical bodies) within a certain range; therefore the observation device cannot be used during the period of the reset operation.

The actuator described in JP 2006-119249 has a further problem in that the protuberance for locking the moving frame (movable portion) and the cam-shaped piece used to engage therewith must be disposed on the outer perimeter of the moving frame, thereby increasing the outside diameter of the actuator.

Also, in the actuator the steel balls (spherical bodies) which lock the moving frame are not themselves locked even when the moving frame (movable portion) is locked, therefore when a shock force acts on a locked moving frame, there is a risk that the steel balls will fall out.

Furthermore, because in the actuator the steel balls are not positioned even when the moving frame (movable portion) is locked, it is difficult to reliably position the steel balls to an appropriate location when recovered to image blur prevention control.

BRIEF SUMMARY OF THE INVENTION

Therefore the present invention has the object of providing an actuator and lens unit and camera furnished therewith capable of positioning spherical bodies at a predetermined position without causing significant blurring of a formed image.

The present invention has the further object of providing an actuator and lens unit and camera furnished therewith capable of positioning spherical bodies at a predetermined position without executing any special operation.

The present invention has the further object of providing an actuator and lens unit and camera furnished therewith capable of locking a movable portion without increasing outside diameter.

The present invention has the further object of providing an actuator and lens unit and camera furnished therewith capable of locking spherical bodies when a movable portion is locked.

The present invention has the further object of providing an actuator and lens unit and camera furnished therewith capable of positioning spherical bodies when a movable portion is locked.

The present invention is an actuator for moving an imaging lens within a plane perpendicular to the optical axis thereof to prevent blurring of an image, comprising a fixed portion; a movable portion attached to the imaging lens; a plurality of spherical bodies sandwiched between the movable portion and the fixed portion, supporting the movable portion such that it can be moved; a drive means for driving the movable portion with respect to the fixed portion, causing the movable member to move rotationally and translationally; fixed portion drop prevention walls provided on the fixed portion so as to surround each of the spherical bodies and prevent the spherical bodies from dropping; fixed portion contact walls formed contiguously with these fixed portion drop prevention walls such that when the movable portion is moved to a predetermined locking position, the spherical bodies make contact therewith; movable portion drop prevention walls provided on the movable portion so as to surround each of the spherical bodies and prevent the spherical bodies from dropping; movable portion contact walls formed contiguously with the movable portion drop prevention walls such that the spherical bodies contact therewith when the movable portion is moved to the locking position; and a control means for controlling the drive means, moving the movable portion to the locking position by rotating the movable portion around the optical axis, thereby positioning each of the spherical bodies and restoring the movable portion to a predetermined image blur prevention control operational center position by rotating the movable portion by a predetermined angle from the locking position.

In the present invention thus constituted, the movable portion to which the imaging lenses are attached is supported by a plurality of spherical bodies so as to be able to move; a drive means drives the movable portion with respect to a fixed portion, thereby moving it rotationally and translationally. Fixed portion drop prevention walls and fixed portion contact walls formed contiguously with these fixed portion drop prevention walls are provided on the fixed portion so as to surround each respective spherical body. Also, movable portion drop prevention walls and movable portion contact walls formed contiguously with these movable portion drop prevention walls are provided on the movable portion so as to surround each respective spherical body. By controlling the drive means to cause the movable portion to rotate around the optical axis, a control means causes the movable portion to move to the locking position, thereby positioning each of the spherical bodies. By causing the movable portion to rotate by a predetermined angle from the locking position, the control means causes the movable portion to be restored to a predetermined image blur prevention control operational center position.

In the present invention thus constituted, each spherical body is positioned by moving the movable portion to which the imaging lenses are attached, therefore the formed image can be prevented from significantly blurring when positioning the spherical bodies. Also, in the present invention thus constituted the spherical bodies are positioned when the movable portion is moved to the locking position, therefore the spherical bodies can be positioned without executing any particular operation, and the position of the spherical bodies can be maintained at an appropriate location when the movable portion is restored to a predetermined image blur prevention control operational center position.

In the present invention, the image blur prevention control operational center position is preferably positioned at essentially the center of a surface on which each spherical body is respectively surrounded by the fixed portion drop prevention walls and the movable portion drop prevention walls.

In the present invention thus constituted, at the image blur prevention control operational center position each spherical body is respectively positioned at essentially the center of a surface surrounded respectively by the fixed portion drop prevention wall and the movable portion drop prevention wall, therefore the surface surrounded by the fixed portion drop prevention walls and the movable portion drop prevention walls can be made narrower while preventing contact by each of the spherical bodies with each of the drop prevention walls. This allows the actuator to be made more compact.

In the present invention, at least either the fixed portion contact walls or the movable portion contact walls are preferably constituted such that the tip thereof tapers, and the spherical bodies contact at least two points or a predetermined area of the tapered portion.

In the present invention thus constituted, the spherical bodies contact at least either the fixed portion contact walls or the movable portion contact walls at least two points or at a predetermined area, therefore the spherical bodies can be reliably positioned.

In the present invention the fixed portion contact walls and the movable portion contact walls preferably protrude in mutually opposite directions essentially tangential to the perimeter of a circle centered on an optical axis.

In the present invention thus constituted, rotating the movable portion around an optical axis enables the interval between the fixed portion contact walls and the movable portion contact walls to be narrowed, thereby enabling the spherical bodies to be placed in contact with each of the contact walls.

In the present invention, the fixed portion drop prevention walls and the fixed portion contact walls, as well as the movable portion drop prevention walls and the movable portion contact walls, are respectively each formed in an approximately teardrop shape.

In the present invention thus constituted, the spherical bodies can be smoothly moved to a position at which they contact the fixed portion contact walls and the movable portion contact walls.

The present invention is an actuator for moving an imaging lens within a plane perpendicular to the optical axis thereof to prevent blurring of an image, comprising: a fixed portion; a movable portion to which the imaging lens is attached; at least three spherical bodies, sandwiched between the movable portion and the fixed portion and supporting the movable portion so that the movable portion is able to move; a drive means for translationally and rotationally moving the movable portion with respect to the fixed portion; fixed portion rolling area demarcation walls provided on the fixed portion so as to surround each of the respective spherical bodies, and to demarcate the rolling area within which the spherical bodies can roll in any direction; movable portion rolling area demarcation walls provided on the movable portion so as to surround each of the respective spherical bodies, and to demarcate the rolling area within which the spherical bodies can roll in any direction; at least two fixed portion restricted area demarcation walls formed to connect with the fixed portion rolling area, extending essentially tangentially relative to a circle centered on the optical axis and demarcating the positionally restricted area restricting the distance from the optical axis to the spherical bodies to a predetermined distance; and movable portion restricted area demarcation walls, corresponding to the respective fixed portion restricted area demarcation walls, for demarcating a positionally restricted area extending essentially tangentially to a circle centered on the optical axis so as to connect to the movable portion rolling area.

In the present invention thus constituted, the movable portion to which the imaging lenses are attached is supported by at least three spherical bodies so as to be movable with respect to the fixed portion. Each spherical body is sandwiched between the inside rolling area of the fixed portion roll area demarcation walls provided on the fixed portion, and the inside rolling area of the movable portion rolling area demarcation walls provided on the movable portion. At least two positionally restricted areas extending in a direction tangential to a circle around the optical axis are demarcated by the fixed portion restricted area demarcation walls and the movable portion restricted area demarcation walls so as to connect with these rolling areas.

In the present invention thus constituted, movement of the movable portion in the radial direction of a circle centered on the optical axis is restricted by at least two points due to the sandwiching of the spherical bodies in at least two positionally restricted areas, therefore translational movement of the movable portion is locked. The movable portion can thus be locked without increasing the outside diameter of the actuator.

The present invention preferably further comprises straight fixed portion adjustment area demarcation walls demarcating a fixed portion adjustment area, connected to and extending from the fixed portion rolling area, as well as movable portion adjustment area demarcation walls demarcating a movable portion adjustment area, connected to and extending from the movable portion rolling area; at least either the fixed portion adjustment area or the movable portion adjustment area is demarcated so as to intersect the perimeter of a circle centered on the optical axis.

In the present invention thus constituted, because the fixed portion adjustment area and/or the movable portion adjustment area intersects the perimeter of a circle centered on the optical axis, the distance from the spherical bodies sandwiched between the fixed portion adjustment area and the movable portion adjustment area to the optical axis can be made variable. A margin of error in the positionally restricted area position and dimensions can thus be tolerated while still reliably positioning the spherical bodies sandwiched between the fixed portion adjustment area and the movable portion adjustment area.

In the present invention there are preferably three sets of fixed portion rolling area demarcation walls and movable portion rolling area demarcation walls; of these, positionally restricted areas are formed in two sets, and a fixed portion adjustment area and a movable portion adjustment area are formed in the other set.

Such a constitution allows for support of the movable portion at three points without looseness.

In the present invention, the surface contacting the spherical bodies surrounded by the fixed portion restricted area demarcation walls or the movable portion restricted area demarcation walls preferably has a curved surface with essentially the same curvature radius as the outer surface of the spherical bodies.

In the present invention thus constituted, in the state wherein the spherical bodies are positioned in the various positionally restricted areas, the surface area contacting the spherical bodies can be increased, therefore the pressure of that contact can be reduced.

The present invention further comprises a rotational locking means which, when the spherical bodies are positioned in the positionally restricted areas of the fixed portion and the movable portion, locks rotation of the movable portion relative to the fixed portion.

In the present invention thus constituted, because the rotational locking means locks the rotation of the movable portion with respect to the fixed portion, the movable portion can be maintained in a state in which translational movement thereof is stopped by each of the positionally restricted areas.

The lens unit in the present invention comprises a lens barrel, a plurality of imaging lenses contained within the lens barrel, and the actuator of the present invention, wherein a portion of these imaging lenses are attached to the movable portion.

Furthermore, the camera of the present invention comprises a camera main unit and the lens unit of the present invention.

Effect of the Invention

The actuator and lens unit and camera equipped therewith of the present invention can position spherical bodies at a predetermined position without significantly causing a formed image to blur.

The actuator and lens unit and camera equipped therewith of the present invention are capable of positioning the spherical bodies at predetermined positions without executing special operations.

The actuator and lens unit and camera equipped therewith of the present invention are capable of locking the movable portion without enlarging the outside diameter.

DETAILED DESCRIPTION OF THE INVENTION

Next we discuss embodiments of the present invention with reference to the attached figures.

First, referring toFIGS. 1 through 11, we discuss a camera according to a first embodiment of the present invention.FIG. 1is a cross section of a camera according to a first embodiment of the present invention.

As shown inFIG. 1, the camera1of the first embodiment of the present invention comprises a lens unit2and a camera main unit4. The lens unit2comprises a lens barrel6, a plurality of imaging lenses8disposed within the lens barrel, an actuator10for moving an image blur compensation lens16from among the imaging lenses within a predetermined plane, and gyros34aand34bserving as a vibration detection means for detecting vibration in the lens barrel6(only34ais shown inFIG. 1).

The lens unit2is attached to the camera main unit4and forms an image of light incident on a film surface F.

The approximately circular lens barrel6holds within it a plurality of imaging lenses8, and implements focus adjustment by moving a portion of the imaging lenses8.

The camera1of the first embodiment of the present invention detects vibration using the gyros34aand34b, operates the actuator10based on the vibration detected, thereby operating the image blur compensation lens16and stabilizing the image focused on the film surface F in the camera main unit4. In the present embodiment, piezoelectric oscillator gyros are used for gyros34aand34b. Note that in the present embodiment the image blur compensation lens16comprises a single lens, but lens groups of multiple lenses may also be used to stabilize an image.

Next, referring toFIGS. 2 through 5, we discuss the constitution of the actuator10.FIG. 2is a front elevation of the actuator10when the moving frame is at the image blur prevention control operational center position.FIG. 3is a front elevation of the actuator10when the moving frame is in the locking position. Additionally,FIG. 4is a side elevation cross section along line IV-IV inFIG. 3, andFIG. 5(a) is a side elevation cross section along line V-V inFIG. 2.FIG. 5(b) is an oblique view showing the state of magnetization of the drive magnets.

As shown inFIGS. 2 through 5, the actuator10comprises a fixed frame12, which is fixed portion affixed within the lens barrel6; a moving frame, which is a movable portion supported to as to be movable with respect to the fixed frame12; and three steel balls serving as spherical bodies to support the moving frame.

Furthermore, the actuator10comprises three drive coils20a,20b, and20cattached to the fixed frame12; and three drive magnets22a,22b, and22con the moving frame attached to the respectively corresponding drive coils20a,20b, and20c.

As shown inFIG. 5(a), in order to cause the moving frame14to be drawn to the fixed frame12by the magnetic force of the drive magnets22a,22b, and22c, the actuator10has a drawing yoke26attached to the fixed frame12, and a back yoke28attached to the rear of the drive magnet so as to effectively direct the magnetic force of the drive magnet toward the fixed frame12. Note that the drive coils20a,20b, and20cand the three drive magnets22a,22b, and22cattached at positions corresponding thereto together form a linear motor, functioning as a drive means to move the moving frame14with translational motion, as well as rotation, relative to the fixed frame12.

Furthermore, as shown inFIG. 5(a), Hall elements24a,22b, and22c, which are magnetic sensors, are disposed on the inside of the windings of each of the drive coils20a,20b, and20c(only24ais shown inFIG. 5). Each Hall element24a,22b, and22cdetects the magnetism of each of the drive magnets22a,22b, and22cdisposed to face the respective Hall elements, thereby detecting the position of the moving frame14relative to the fixed frame12. These Hall elements24a,22b, and22cand drive magnets22a,22b, and22cconstitute position detection means.

As shown inFIG. 1, the actuator10has a controller36, which is a controlling means for controlling the current sourced to each of the drive coils20a,20b, and20cbased on the vibration detected by the gyros34aand34b, and on moving frame14, positional information detected by each of the drive coils20a,20b, and20c. Furthermore, a locking position movement means37for moving the moving frame14to the locking position, which is the target position, and a locking direction biasing means47for outputting a signal for biasing the moving frame14toward the locking position, are built into the controller36.

The actuator10causes the moving frame14to move within a plane parallel to the film surface F relative to the fixed frame12affixed to the lens barrel6, thereby moving the image blur compensation lens16attached to the moving frame14, thus driving the moving frame14in such a way that the image formed on the film surface F is not distorted even if the lens barrel6vibrates.

The fixed frame12, as shown inFIG. 2, has a donut shape formed by a rim around a circle. Also, fixed frame receiving portions13a,13b, and13c, which are concavities for receiving each of the steel balls18, are formed on the fixed frame12. Details about these fixed frame receiving portions are discussed below. Furthermore, a locking hook17, which is a rotational locking means for locking the moving frame14, is rotatably attached to the fixed frame12. This locking hook17is joined to a solenoid (not shown), and is rotated in order to lock the moving frame14.

The moving frame14, as shown inFIG. 2, has an approximately donut shape, and is disposed so as to be surrounded by the edge of the fixed frame12within the fixed frame12. An image blur compensation lens16is attached at the center opening of the moving frame14. Moving frame receiving portions15a,15b, and15c, which are concavities for receiving each of the steel balls18, are formed on the moving frame14. Details of the moving frame receiving portions are discussed below. Additionally, a locking protuberance17a, which engages the locking hook17during locking, is formed at the position corresponding to the locking hook17on the moving frame14.

As shown inFIG. 4, the steel balls18are respectively disposed between each of the fixed frame receiving portions13a,13b, and13cformed on the fixed frame12and each of the moving frame receiving portions15a,15b, and15cformed on the moving frame14. Three of the steel balls18, as shown inFIGS. 2 and 3, are respectively separated by a center angle of 120°, so as each to be positioned between the respective drive coils. Each steel ball18is disposed within the receiving portions formed between the fixed frame12and the moving frame14; the moving frame14is drawn to the fixed frame12by a drive magnet22, therefore each steel balls18is sandwiched between the fixed frame12and the moving frame14. The moving frame14is thus supported on a plane parallel to the fixed frame12, and each steel ball18rolls while being sandwiched, thereby permitting translational and rotational movement of the moving frame14in any desired direction relative to the fixed frame12.

In the present embodiment, steel spheres are used as the steel balls18, but the steel balls18do not necessarily have to be spheres. That is, any steel balls18may be used so long as the portion making contact between the fixed frame12and the moving frame14during the operation of the actuator10is approximately a spherical surface. Note that in the present Specification, this type of shape is referred to as a spherical body.

The three drive coils20a,20b, and20care respectively disposed on the fixed frame12. The centers of these drive coils20a,20b, and20care respectively disposed on a perimeter centered on the optical axis of the lens unit2. In the present embodiment, the drive coil20ais disposed at a position vertically above the optical axis, and drive coils20band20care disposed at intervals separated by a center angle of 120° each relative to the drive coil20a. In other words, the drive coils20a,20b, and20care disposed at equal intervals on a circle centered on the optical axis. The windings of the drive coils20a,20b, and20care respectively wound in a rectangular shape with rounded corners, whereby the center line of that rectangle coincides with the radial direction of the circle.

The drive magnets22a,22b, and22ceach have a rectangular shape, and are set into the moving frame14. The drive magnets22a,22b, and22care also positioned at positions corresponding to each of the drive magnets22a,22b, and22con the circumference of the moving frame14. Note that in the present Specification the “position corresponding to the drive coil” means the position at which the effect of the magnetic fields formed by the drive coils is substantially imparted.

The three drawing yokes26are attached to the rear side of each of the drive coils on the fixed frame12, i.e. to the opposite side of the moving frame14. Each drawing yoke26is drawn by the magnetic force of the drive magnets22a,22b, and22cpositioned in correspondence thereto, and the moving frame14is thus drawn to the fixed frame12. Note that in the present embodiment, the fixed frame12is composed of a non-magnetic material so that the magnetic field lines of the drive magnet efficiently reach the drawing yokes26.

The back yokes28have an approximately rectangular shape, and are respectively disposed at the rear side of the three drive magnets. As shown inFIG. 5(a), by attaching each of the back yoke28to the rear sides of each of the drive magnets, i.e. to the reverse side of each of the drive coils, the flux of each of the drive coils is efficiently directed toward the fixed frame12(inFIGS. 2 and 3the back yokes28are removed).

Next, referring toFIG. 5, we discuss the magnetic force imparted by the drive magnets. The approximately rectangularly formed drive magnets22a,22b, and22c, back yokes28, and drawing yokes26are each disposed so that each of their long sides and short sides overlaps. The drive coils20a,20b, and20care disposed so that their respective sides are parallel to the long sides and short sides of the rectangular back yoke28. Furthermore, each drive magnet is oriented in such a way that the magnetization boundary line C, which is the boundary line between the magnetic poles thereof, matches the radial direction of the circle on which each of the drive magnets is disposed.

The drive magnet22a, back yoke28, and drawing yoke26thus form a magnetic circuit, forming magnetic force lines as shown by the arrows inFIG. 5(a). When current flows in the corresponding drive coil20a, the drive magnet22areceives a drive force in a direction tangential to the circle on which each of the drive magnets is disposed. Drive magnets22band22b, back yoke28, and drawing yokes26, correlated in the same positional relationship, are also disposed relative to the other drive coils20band20c.

Note that in the present Specification, the “magnetization boundary line C” refers to the magnetic pole boundary line which is magnetized when magnetization occurs such that the two ends of the drive magnet become respectively S and N poles. Therefore in the present embodiment the magnetization boundary line C is positioned to pass through the center point of the long side of the rectangular drive magnet. Additionally, as shown inFIG. 5(b), polarity also changes in the thickness direction of the drive magnets22a, such that the lower left corner of5(b) is an S pole; the lower right is an N pole, the upper left is an N pole, and the upper right is an S pole.

Next, referring toFIGS. 6 and 7, we discuss detection of the moving frame14position.

FIGS. 6 and 7describe the relationship between the movement of the drive magnet22aand the signals output from the Hall element24a. As shown inFIG. 6, when the sensitivity center point S of the Hall element24ais positioned on the drive magnet22amagnetization boundary line C, the output signal from the Hall element24ais zero. When the drive magnet22ais moved together with the moving frame14, and the sensitivity center point of the Hall element24aseparates from the drive magnet22amagnetization boundary line, the output signal of the Hall element24achanges. As shown inFIG. 6, when the drive magnet22amoves in the direction perpendicular to the magnetization boundary line C, i.e. in the X axis direction, the Hall element24agenerates a sine wave. Therefore when the amount of movement is very small, the Hall element24aemits a signal essentially proportional to the distance of movement by the drive magnet22a. In the present embodiment, when the distance of movement of the drive magnet22ais within about 3% of the length of the long side of the drive magnet22a, the signal output from the Hall element24ais essentially proportional to the distance between the Hall element24asensitivity center point S and the drive magnet22amagnetization boundary line C. Also, in the present embodiment the actuator10is such that in the normal operating area the output of each Hall element operates in a manner which is essentially proportional to distance.

As shown inFIGS. 7(a) through (c), when the magnetization boundary line C of drive magnet22ais positioned on the sensitivity center point S of Hall element24a, the output signal from the Hall element24awill be zero both when the drive magnet22arotates, as shown inFIG. 7(b), and when the drive magnet22amoves toward the magnetization boundary line C. When, as shown inFIGS. 7(d) through (f), the magnetization boundary line C of drive magnet22aseparates from the sensitivity center point S of Hall element24a, a signal proportional to the distance r between the sensitivity center point S and the magnetization boundary line C is output from the Hall element24a. Therefore if the distance r from the sensitivity center point S to the magnetization boundary line C is the same, then whether the drive magnet22ais perpendicular to the magnetization boundary line C as shown inFIG. 7(a), or the drive magnet22amoves translationally and rotationally as shown inFIG. 7(e), or it moves translationally in any desired direction, a signal of the same magnitude will be output from the Hall element24a.

We have here discussed the Hall element24a, but a similar signal is also output from the other Hall elements24band24cbased on the positional relationships between the drive magnets22band22ccorresponding thereto. It is therefore possible to identify the position to which the moving frame14has moved translationally and rotationally with respect to the fixed frame12based on the signal detected by each of the Hall elements24a,22b, and22c.

Next, referring toFIG. 8, we discuss image blur prevention control by the actuator10.FIG. 8is a block diagram showing signal processing in the controller36. As shown inFIG. 8, vibration of the lens unit2is detected from moment to moment by the two gyros34aand34band input to computing circuits38aand38b, which serve as lens position command signal generating means, and are built into the controller36. In the present embodiment, the gyros34aand34bare constituted and positioned to respectively detect the angular velocities of the yawing and pitching motions of the lens unit2.

Based on angular velocities input from moment to moment from the gyros34aand34b, the computing circuits38aand38bgenerate a lens position command signal which commands the position to which the image blur compensation lens16should move in a time sequence. That is, the computing circuit38aperforms a time integration of the angular velocity of the yawing motion detected by the gyro34ato perform a predetermined optical characteristic compensation, thus generating the horizontal component Dx for the lens position command signal; similarly the computing circuit38bperforms a time integration of the angular velocity of the pitching motion detected by the gyro34bto perform a predetermined optical characteristic compensation, thus generating the vertical component Dy for the lens position command signal. By moving the image blur compensation lens16from moment to moment in accordance with a lens position command signal obtained in this manner, the image focused on the film surface F within the camera main unit4is stabilized without distortion even when the lens unit2vibrates during photographic exposure.

A coil position command signal generating means built into the controller36is constituted to generate coil position command signals to each drive coil based on lens position command signals generated by the computing circuits38aand38b. The coil position command signal expresses the positional relationship between the drive coils20a,20b, and20cand the drive magnets22a,22b, and22ccorresponding thereto when the image blur compensation lens16is moved to a position specified by the lens position command signal. That is, when each drive magnet is moved to a position relative to each coil commanded by the coil position command signal, the image blur compensation lens16is moved to the position commanded by the lens position command signal as a result. In the present embodiment, the drive coil20ais disposed vertically above the optical axis, hence the coil position command signal ra relative to the drive coils20ais equivalent to the horizontal component Dx of the lens position command signal output from the computing circuits38a. Therefore a computing circuit40a, which is the coil position command signal generating means which generates the coil position command signal relative to the drive coil20a, outputs the output from the computing circuit38aas is. In the meantime, the coil position command signals rb and rc relative to the drive coils20band20care generated by computation circuits40band40cserving as coil position command signal generating means, based on the lens position command signal horizontal component Dx and vertical component Dy.

The degree of movement of the drive magnets relative to each drive coil as measured by the Hall elements24a,22b, and22cis amplified by a predetermined multiplier by magnetic sensor amps42a,42b, and42c. The drive circuits44a,44b, and44csource a current to each of the drive coils20a,20b, and20cproportional to the difference between each of the coil position command signals ra, rb, and rc output from the computing circuits40a,40b, and40c, and the signals output from each of the magnetic sensor amps42a,42b, and42c. Therefore when the difference between the coil position command signal and the output from each of the magnetic sensor amps disappears, i.e. when each drive magnet reaches the position commanded by the coil position command signal, current stops flowing in each of the drive coils and the drive force operating on the drive magnets goes to zero. Note that a selector switch45and a second selector switch46disposed between the computing circuits40a,40b, and40cand drive circuits44a,44b, and44care positioned to connect directly with the computing circuits and the drive circuits at al times during the image blur prevention control mode.

Next, referring toFIG. 9, we discuss the relationship between the lens position command signal and the coil position command signal when the moving frame14is moved translationally.FIG. 9is a diagram depicting the positional relationship between the drive coils20a,20b, and20cdisposed on the fixed frame12and the drive magnets22a,22b, and22cdisposed on the moving frame14. First, the center points of the three drive coils20a,20b, and20care respectively disposed at points Sa, Sb, and Sc on a circle of radius R with origin point Q. Furthermore, each Hall element24a,22b, and22cis also respectively disposed so that the sensitivity center points S thereof are positioned at points Sa, Sb, and Sc. Moreover, when the moving frame14is at the operational center position, the center of the image blur compensation lens16and the optical axis of the imaging lenses8match, such that the center points of the magnetization boundary line C of each drive magnet corresponding to each of the drive coils are also positioned at points Sa, Sb, and Sc respectively, and each magnetization boundary line C is oriented in the radial direction of a circle centered on point Q. The moving frame14is translationally moved around this operational center position to execute image blur prevention control.

Next, assuming a horizontal axis X and a vertical axis Y, each originating at point Q, we consider the case in which the center point Q1of the image blur prevention lens16moves translationally by Dy in the Y axis direction and −Dx in the X axis direction. When the moving frame14is moved in this manner, the magnetization boundary line C of each of the drive magnets22a,22b, and22cis moved to a position shown by the dot and dash line inFIG. 9. We here define the distance between the drive magnet22amagnetization boundary line C and the point Sa as ra, the distance between the drive magnet22bmagnetization boundary line C and the point Sb as rb, and the distance between the drive magnet22cmagnetization boundary line C and the point Sc as rc. These distances ra, rb, and rc correspond to the movement distance detected by each of the Hall elements24a,22b, and22cwhen the image blur prevention lens16is moved by Dy in the Y axis direction and −Dx in the X axis direction. These distances ra, rb, and rc are uniquely defined relative to movement distances Dx and Dy in the X axis and Y axis directions. It is therefore sufficient in order to move the image blur prevention lens16by Dx and Dy respectively in the X and Y axis directions to apply distances ra, rb, and rc corresponding thereto as coil position command signals.

Defining the positive direction of the distances ra, rb, and rc as shown by the arrows a, b, and c inFIG. 9, the relationship of ra, rb, and rc to Dx and Dy is given by the following (Equation 1):

The computing circuits40a,40b, and40cexplained inFIG. 8execute computations corresponding to the respective equations in Equation 1 above to generate position command signals for each coil.

Next we discuss the coil position command signal when the moving frame14is rotated. The moving frame14can be rotated by using the same value as the position command signal for each coil. That is, the coil position command signal required to turn the moving frame14by an angle θ [rad] is given as follows:
ra=Rθ
rb=Rθ
rc=Rθ  (Equation 2)

Thus the turning of each drive magnet by the same distance in the tangential direction with respect to each drive coil results in the moving frame14being rotated around an optical axis while maintaining the optical axis of the image blur compensation lens16and the imaging lenses8optical axis in alignment.

Next, referring toFIGS. 1 through 8, we discuss the action of a camera1in an embodiment of the present invention. First, when the power switch (not shown) to the camera1hand vibration function is turned on, the actuator10provided on the lens unit2is activated. The gyros34aand34battached to the lens unit2detect vibration in a predetermined frequency band from moment to moment, outputting those values to computing circuits38aand38bbuilt into the controller. The gyro34aoutputs a yawing direction angular velocity signal for the lens unit2to the computing circuit38a; the gyro34boutputs a pitching direction angular velocity for the lens unit2to the computing circuit38b. The computing circuit38aperforms a time integration of the input angular velocity signal, calculates a yawing angle, and adds a predetermined optical characteristic correction to generate the horizontal lens position command signal Dx. Similarly, the computing circuit38bperforms a time integration of the input angular velocity signal, calculates a pitching angle, and adds a predetermined optical characteristic correction to generate the horizontal lens position command signal Dy. By moving the image blur compensation lens16from moment to moment to a position specified by the lens position command signal output in a time sequence by the computing circuits38aand38b, the image focused on the film surface F in the camera main unit4is stabilized.

The horizontal lens position command signal Dx output by the computing circuit38ais output via the computing circuit40aas the coil position command signal ra relative to the drive coil20a. Horizontal lens position command signal Dx and vertical lens position command signal Dy are input to the computing circuit40b, and a coil position command signal rb relative to the drive coil20bis generated based on the middle equation in Equation 1. Similarly, the lens position command signals Dx and Dy are input to the computing circuit40c, and a coil position command signal rc is generated based on the bottom equation in Equation 1.

At the same time, the Hall element24acorresponding to the drive coil20aoutputs a detection signal to a magnetic sensor amp42a. The detection signal, amplified by the magnetic sensor amp42a, is subtracted from the coil position command signal corresponding to the drive coil20a, and a current proportional to this difference is output via a drive circuit44ato the drive coil20a. Similarly, a current proportional to the difference between the Hall element24bdetection signal and the coil position command signal rb is output via a drive circuit44bto the drive coil20b, and a current proportional to the difference between the Hall element24cdetection signal and the coil position command signal rc is output via a drive circuit44cto the drive coil20c.

A magnetic field proportional to the current is generated as a result of current flowing in each of the drive coils. This magnetic field causes each drive magnet, disposed in correspondence to each drive coil, to receive a drive force in a direction approaching a position designated by the coil position command signals ra, rb, and rc, such that the moving frame14is moved. When the drive magnets reach the position designated by the coil position command signal, the coil position command signal and the Hall element detection signal coincide, so the output of the drive circuit becomes zero, and the drive force becomes zero. When each drive magnet separates from the position designated by the coil position command signal through disturbances or changes or the like in the coil position command signal, current is again sourced to each drive coil, and each drive magnet returns to the position designated by the coil position command signal.

By moment to moment repetition of the operations, the image blur compensation lens16attached to the moving frame14carrying each of the drive magnet moves in such a way as to follow the lens position command signal. The image focused on the film surface F in the camera main unit4is thus stabilized.

Next, referring toFIGS. 10 and 11, we discuss the mechanism for positioning the steel balls supporting the actuator10moving frame14built into the camera1of the first embodiment of the present invention, as well as the action thereof.FIGS. 10 and 11depict an expanded view of the fixed frame receiving portion and the moving frame receiving portion respectively formed on the fixed frame12and the moving frame14. That is,FIG. 10shows (a) a front elevation, (b) a cross section along line b-b in (a), and (c) a cross section along line c-c in (a) of the fixed frame receiving portion13aformed on the fixed frame12.FIG. 11shows the positional relationship between the fixed frame receiving portion13aformed on the fixed frame12, and the moving frame receiving portion15aformed on the moving frame14; (a) depicts the image blur compensation control operational center position, (b) the state of movement to the locking position, and (c) the locking position.

As described above, the actuator10causes the moving frame14to move translationally around the operational center position shown inFIG. 2when image blur prevention control is being executed, thereby stabilizing the image. On the other hand, when image blur prevention control is not being executed, or the camera1is not in use, the moving frame14is moved to the locking position shown inFIG. 3. In the present embodiment, the locking position is set at a position to which the moving frame14is rotated clockwise around the optical axis of the image blur compensation lens16from the operational center position shown inFIG. 2.

The fixed frame receiving portions13a,13b, and13cformed on the fixed frame12and the moving frame receiving portions15a,15b, and15cformed on the moving frame14are concavities formed respectively on the fixed frame12and the moving frame14; disposition of each steel ball18in these concavities, serves to prevent the dropping down of the steel balls18and, at the locking position, to position the steel balls18.

Next we discuss the constitution of the fixed frame receiving portions13a,13b, and13cand the moving frame receiving portions15a,15b, and15c. As shown inFIG. 2, the fixed frame receiving portions13a,13b, and13care disposed on a circle D centered on the optical axis of the fixed frame12, and are positioned between each of the drive coils at a mutual spacing of 120° each. Furthermore, each of the fixed frame receiving portions13a,13b, and13cis respectively formed in the same shape.

At the same time, the moving frame receiving portions15a,15b, and15care formed at positions respectively corresponding to the fixed frame receiving portions13a,13b, and13con the moving frame14. In other words, each of the moving frame receiving portions is disposed on a circle D centered on the optical axis, positioned between each of the drive magnets at a mutual spacing of 120°. Furthermore, each of the moving frame receiving portions15a,15b, and15cis respectively formed in the same shape.

As shown inFIG. 10(a), the fixed frame receiving portion13ahas a fixed portion drop prevention wall50formed in an approximately arc shape, and a fixed portion contact wall52formed contiguously with the fixed portion drop prevention wall50. Also, as shown inFIG. 10(c), the inner side of the fixed portion drop prevention wall50is formed to be flat, and the steel balls18can roll in any desired direction on the inner side of the fixed portion drop prevention wall50. At the same time, the fixed portion contact wall52is formed continuously with the fixed portion drop prevention wall50so as to protrude in essentially the radial direction of a circle surrounded by the fixed portion drop prevention wall50. The fixed portion contact wall52is constituted to taper toward the tip; that tip describes a curve having essentially the same curvature radius as the radius of the steel balls18. Therefore the fixed portion drop prevention wall50and the fixed portion contact wall52as a whole are formed to describe approximately a teardrop shape. Moreover, the fixed portion contact wall52is directed to protrude in essentially the tangential direction of the circle D (FIG. 2)centered on the optical axis.

The steel ball18within the fixed frame receiving portion13arolls inside the fixed portion drop prevention wall50and does not contact the fixed portion drop prevention wall50during image blur prevention control. On the other hand, the steel ball18does contact the fixed portion contact wall52at the locking position, but because the tip of the fixed portion contact wall52is formed with essentially the same curvature radius as the steel balls18, the ball makes contact with the fixed portion contact wall52in an area having a certain breadth.

Meanwhile, the moving frame receiving portion15aformed on the moving frame14in correspondence to the fixed frame receiving portion13ahas essentially the same shape as the fixed frame receiving portion13a, and is furnished with a movable portion drop prevention wall54and a movable portion contact wall56(FIG. 11). Also, as shown inFIG. 2, the moving frame receiving portion15amovable portion contact wall56also protrudes in essentially the tangential direction of the circle D, but protrudes in the opposite direction to the fixed frame receiving portion13afixed portion contact wall52.

Note that while we have here explained the constitution of the fixed frame receiving portion13aand the moving frame receiving portion15a, the fixed frame receiving portions13band13cand the moving frame receiving portions15band15care constituted in exactly the same way, as shown inFIGS. 2 and 3.

Next, referring toFIG. 11, we discuss the relative positions of the fixed frame receiving portion13aand the moving frame receiving portion15a, and the position at which the steel ball18rolls.

First, as shown inFIG. 11(a), the fixed portion drop prevention wall50of fixed frame receiving portion13aand the movable portion drop prevention wall54of moving frame receiving portion15aare in essentially a superimposed state at the image blur compensation control operational center position. In this state, the steel balls18are positioned near the center of the fixed portion drop prevention wall50and the movable portion drop prevention wall54. During the image blur compensation control operation, the relative movement of the moving frame14with respect to the fixed frame12results in the steel balls18being moved within the fixed portion drop prevention wall50and the movable portion drop prevention wall54. For example, inFIG. 11(a), when the moving frame14has been moved to the upper position relative to the fixed frame12, the moving frame receiving portion15ais moved to the position shown by the dotted line in the figure; at this point the steel balls18are also moved to the position shown by the dotted line.

Next, when moving the frame14to the locking position, the moving frame14is moved in a clockwise direction (toward the right in the diagram) from the image blur compensation control operational center position shown inFIG. 11(a). This results, as shown inFIG. 11(b), in a narrowing of the overlapping portion between the fixed frame receiving portion13aand the moving frame receiving portion15a, such that the steel balls18approach the fixed portion contact wall52and the movable portion contact wall56.

Next, as shown inFIG. 11(c), when the moving frame14is moved to the locking position, the overlapping portion between the fixed frame receiving portion13aand the moving frame receiving portion15ais minimized, and the steel balls18contact the fixed frame receiving portion13aand the moving frame receiving portion15a. In this state, that is, the steel balls18respectively contact the fixed portion contact wall52and the moving frame receiving portion15ain an area having a certain breadth, therefore the steel balls18are uniquely positioned. Also, in this state movement of the moving frame receiving portion15ain the direction tangential to the circle D relative to the fixed frame receiving portion13a(the vertical direction as seen inFIG. 11)is impeded by the steel balls18, and only movement of the moving frame receiving portion15ain the circular direction (the horizontal direction as seen inFIG. 11) is permitted.

Here, as shown inFIG. 3, when the moving frame14has been moved to the locking position, the fixed frame receiving portions13band13cand the moving frame receiving portions15band15care all moved to similar relative positions as seen inFIG. 11(c). Therefore in the three sets of fixed frame receiving portions and moving frame receiving portions, movement of the moving frame receiving portion relative to the fixed frame receiving portion is blocked in the circle D radial direction by the steel balls18, and only movement in the circular direction is permitted. This results in restriction of translational movement by the moving frame14in the locking position, such that only rotation around the optical axis of the image blur compensation lens16is permitted. In this locking position, the optical axis of the image blur compensation lens16attached to the moving frame14matches the optical axis of other imaging lenses8.

Next we discuss the mode of action for moving the moving frame14to the locking position.

First, when the power switch (not shown) to the camera1hand vibration function is turned off, the actuator10provided on the lens unit2is activated. The gyros34aand34battached to the lens unit2detect vibration in a predetermined frequency band from moment to moment, outputting that value to computing circuits38aand38bbuilt into the controller. The gyro34aoutputs a yawing direction angular velocity signal for the lens unit2to the computing circuit38a; the gyro34boutputs a pitching direction angular velocity for the lens unit2to the computing circuit38b. The computing circuit38aperforms a time integration of the input angular velocity signal, calculates a yawing angle, and adds a predetermined optical characteristic correction to generate the horizontal lens position command signal Dx. Similarly, the computing circuit38bperforms a time integration of the input angular velocity signal, calculates a pitching angle, and adds a predetermined optical characteristic correction to generate the horizontal lens position command signal Dy. By moving the image blur compensation lens16from moment to moment to a position specified by the lens position command signal output in a time sequence by the computing circuits38aand38b, the image focused on the film surface F in the camera main unit4is stabilized.

This causes the fixed frame receiving portions13a,13b, and13cand the moving frame receiving portions15a,15b, and15cto move from the state shown inFIG. 11(a) to the state shown inFIG. 11(b). Also, the controller36sends a signal to a solenoid (not shown) linked to the locking hook17(FIG. 2), thereby energizing the solenoid and causing the locking hook17to rotate to the position shown by the imaginary line.

When the moving frame14is further rotated in the clockwise direction and each steel ball18approaches the fixed portion contact wall52and the movable portion contact wall56, the controller36sends a signal to the second selector switch46(FIG. 8), changing the second selector switch46to the position at which a signal from the locking direction biasing means47is input to each of the drive circuits44a,44b, and44c. By this means, the outputs of the magnetic sensor amps42a,42b, and42care isolated from the inputs to the drive circuit44a, and the same current flows to the drive coils20a,20b, and20cregardless of the detection signals on each of the Hall elements24a,22b, and22c. As explained in Equation 2, sourcing the same current to each of the drive coils20a,20b, and20ccorresponds to driving the moving frame14in the rotary direction only. Therefore after the second selector switch46has been switched, the moving frame14is driven in the rotary direction only, and thereby controlled.

When the moving frame14is then further rotated clockwise and reaches the position shown inFIG. 3, the steel balls18sandwiched between the fixed frame receiving portions13a,13b, and13cand the moving frame receiving portions15a,15b, and15crespectively contact the fixed portion contact wall52and the movable portion contact wall56.

When the moving frame14reaches the position shown inFIG. 3, the controller36sends a signal to the solenoid (not shown) and stops energizing it, so that the locking hook17is rotated to the position shown by the solid line inFIG. 3. As a result, the locking hook17attached to the fixed frame12engages with the locking protuberance17aprovided on the moving frame14. Here, in the state depicted inFIG. 3, movement of the moving frame14with respect to the fixed frame12is restricted to rotation only by the fixed portion contact wall52and the movable portion contact wall56, and by the action of the steel balls18sandwiched therebetween. In this state, the engaging of the locking hook17and the locking protuberance17aresults in restricted rotation by the moving frame14, such that translational and rotational movement of the moving frame14is locked.

Finally, the controller36stops the energizing of each of the drive coils20a,20b, and20c. The moving frame14is locked in a state whereby energizing of the solenoid (not shown) is stopped, therefore the moving frame14can be maintained in the locking position without consuming power.

Furthermore, because in the locked state each steel ball18is respectively sandwiched between the fixed portion contact wall52and the movable portion contact wall56, each steel ball18is locked inside the fixed frame receiving portion and the moving frame receiving portion, and there is no looseness. The position of the steel balls18in the locking position is restricted to being inside an area surrounded by the fixed portion contact wall52and the movable portion contact wall56, and is thus essentially uniquely determined.

Next, when the moving frame14is restored from the locking position to the operational center position, the controller36sends a signal to the solenoid (not shown) and energizes it, thereby rotating the locking hook17to the position shown by imaginary lines inFIG. 3. This results in a release of the engagement between the locking hook17and the locking protuberance17a. Next, the locking position movement means37outputs a lens position command signal causing the moving frame14to rotate by a predetermined angle in the counterclockwise direction, such that the moving frame14is restored to the image blur compensation control operational center position shown inFIG. 2. The controller36then further sends a signal to the solenoid (not shown) and stops energizing it, causing the locking hook17to rotate to the position shown by the solid line inFIG. 2.

Here, in the locking position, the position of each steel ball18is essentially uniquely determined. By rotating the moving frame14from the locking position counterclockwise by a predetermined angle, the position to which each steel ball18is moved by rolling is also essentially uniquely determined. The position of the steel balls18within the fixed portion drop prevention wall50and the movable portion drop prevention wall54when the actuator10is restored to the operational center position can therefore be set at an appropriate position.

Using the camera of the first embodiment of the present invention, a moving frame to which an image blur compensation lens is attached can be rotated to move it to a locking position, thereby determining the position of each steel ball so that a formed image can be prevented from significantly blurring when steel balls are positioned.

Additionally, using the camera of the present embodiment, the steel balls are positioned together with the operation of moving the moving frame to a locking position when stopping the image blur compensation control or turning off the power supply, etc., therefore the steel balls can be positioned without executing any particular operation, and the position of the steel balls when the moving frame is restored to a predetermined image blur compensation control operational center position can be maintained appropriately.

Additionally, using the camera of the present embodiment, each steel ball is positioned at essentially the center of a surface surrounded by a fixed portion drop prevention wall and a movable portion drop prevention wall, therefore the surface surrounded by the fixed portion drop prevention wall and the movable portion drop prevention wall can be constituted as a narrow surface while preventing contact by each of the steel balls with each of the drop prevention walls. This permits the size of the actuator to be reduced.

With the camera of the present embodiment, when locked, the steel balls make contact in a predetermined area with the fixed portion contact wall and the movable portion contact wall, therefore the steel balls can be reliably positioned.

Furthermore, with the camera of the present embodiment the fixed portion contact wall and the movable portion contact wall protrude in directions essentially tangential to a circle centered on the optical axis and in directions opposite to one another, therefore by rotating the moving frame in a predetermined direction around the optical axis, the gap between the fixed portion contact wall and the movable portion contact wall can be narrowed, and the steel balls brought into contact with each of the contact walls.

Also, using the camera of the present embodiment, the fixed portion drop prevention wall and the fixed portion contact wall, and the movable portion drop prevention wall and the movable portion contact wall, are respectively formed in approximately a teardrop shape, such that the steel balls can be smoothly moved to a position at which they contact the fixed portion contact wall and the movable portion contact wall.

Furthermore, using the camera of the present embodiment, the locking hook locks the rotation of the moving frame with respect to the fixed frame, thus enabling the moving frame to be maintained in a state whereby translational movement thereof is locked.

Also, in the camera of the present embodiment of the present invention, when the moving frame is moved to the locking position, the moving frame can be driven by switching the second selector switch and applying the locking direction biasing means. The moving frame is thus biased so as to be rotated in the locking direction by the output of the locking direction biasing means, regardless of position command signals output from the Hall elements. As a result, drive force is generated in the direction in which movement of the moving frame is restricted; excessive flow of current to the drive coil can be prevented, and the moving frame can be biased in the locking direction by an appropriate current.

In the embodiment described above, the fixed portion drop prevention wall, fixed portion contact wall, movable portion drop prevention wall, and movable portion contact wall were formed by forming concavities in the fixed frame or the moving frame, but these walls can also be formed by protrusions from the fixed frame or the moving frame.

Furthermore, the embodiment described above was constituted such that each of the steel balls made contact with the fixed portion contact wall and the moving portion contact wall in an area having a certain breadth, but the steel balls could also make contact with the contact walls at two or more points. Also, it is not necessary for each of the steel balls to make contact with both the fixed portion contact wall and the moving portion contact wall in an area having a certain breadth or with two or more points; it is also acceptable for the balls to make contact with either the fixed portion contact wall or the moving portion contact wall at a single point.

In the embodiment described above, each steel ball makes contact simultaneously with both the fixed portion contact wall and the moving portion contact wall, but it is not required that each steel ball necessarily make contact simultaneously with both contact walls; it is sufficient for the steel balls to be disposed with a sufficiently small gap between each of the contact walls.

Next, referring toFIGS. 12 through 17, we discuss a camera according to a second embodiment of the present invention. The camera of the present embodiment differs from that of the first embodiment described above with respect to its mechanism for locking the built-in actuator moving frame, and the action thereof. Therefore we will here discuss only those portions which differ from the first embodiment, and will omit a discussion of similar parts.

FIG. 12is a front elevation of an actuator110built into a camera according to the second embodiment of the present invention; shown here is the state in which a moving frame is in the image blur compensation control operational center position.FIG. 13is a front elevation of the actuator110with a moving frame114in the locking position.FIGS. 14 through 17depict an expanded view of a fixed frame receiving portion and a moving frame receiving portion respectively formed on the fixed frame112and the moving frame114. That is,FIG. 14shows (a) a front elevation, (b) a cross section along line b-b in (a), and (c) a cross section along line c-c in (a) of a fixed frame receiving portion113aformed on the fixed frame112.FIG. 15shows the positional relationship between the fixed frame receiving portion113aformed on the fixed frame112, and the moving frame receiving portion115aformed on the moving frame114; (a) depicts the image blur compensation control operational center position, (b) the state of movement to the locking position, and (c) the locking position. Additionally,FIG. 16shows (a) a front elevation, (b) a cross section along line b-b in (a), and (c) a cross section along line c-c in (a) of a fixed frame receiving portion113c.FIG. 17shows the positional relationship between the fixed frame receiving portion113cand the moving frame receiving portion115c; (a) depicts the image blur compensation control operational center position, (b) the state of movement to the locking position, and (c) the locking position.

As described above, the actuator110translationally moves the moving frame114around the operational center position shown inFIG. 12when under image blur compensation control, thereby stabilizing an image. When image blur compensation control is not executed or the camera is not in use, on the other hand, the moving frame114is moved to the locking position shown inFIG. 13. In the present embodiment the locking position is set at a position whereby the moving frame114is caused to rotate from the operational center position shown inFIG. 12clockwise around the optical axis of an image blur compensation lens116.

The fixed frame receiving portions113a,113b, and113cformed on the fixed frame112and the moving frame receiving portions115a,115b, and115cformed on the moving frame114are concavities respectively formed on the fixed frame112and the moving frame114; disposition of each of steel ball118in these concavities serves to prevent dropping down of the steel balls118and, at the locking position, to lock the moving frame114.

Next we discuss the constitution of the fixed frame receiving portions113a,113b, and113cand the moving frame receiving portions115a,115b, and115c. As shown inFIG. 12, the fixed frame receiving portions113a,113b, and113care disposed on a circle D centered on the optical axis of the fixed frame112, and are positioned between each of the drive coils at a mutual spacing of 120° each. Furthermore, each of the fixed frame receiving portions113a,113b, and113cdisposed on both sides of a drive coil120is respectively formed in the same shape, and the fixed frame receiving portion113cdisposed between the drive coils120band120cdiffers in shape from the fixed frame receiving portion113aand fixed frame receiving portion113b.

At the same time, the moving frame receiving portions115a,115b, and115care formed at positions respectively corresponding to the fixed frame receiving portions113a,113b, and113con the moving frame114. In other words, each of the moving frame receiving portions is disposed on a circle D centered on the optical axis, positioned between each of the drive magnets at a mutual spacing of 120°. Furthermore, each of the fixed frame receiving portions moving frame receiving portions115a,115b, and115cis respectively formed in the same shape, and the moving frame receiving portion115cdisposed between drive magnets122band122cdiffers in shape from the moving frame receiving portions115aand115b.

As shown inFIG. 14(a), the fixed frame receiving portion113ahas a rolling area150shaped as approximately a circular depression, and a positionally restricted area152formed connecting to this rolling area150. The rim of the rolling area150is demarcated by a fixed portion rolling area demarcation wall150a. As shown inFIG. 14(c), the rolling area150is a relatively broad area, the bottom surface of which is to be formed flat; in this area the steel ball118can roll in any desired direction. At the same time, the positionally restricted area152is formed to connect from the rolling area150, and is constituted to protrude in an essentially radial direction from the approximately circular rolling area150. The positionally restricted area152is a narrow width area, extending in a direction essentially tangential to a circle D (FIG. 112)centered on the optical axis. The rim of the positionally restricted area152is demarcated by a fixed portion restricted area demarcation wall152a. As shown inFIG. 14(b), the positionally restricted area152is formed such that its bottom surface is arc-shaped in section; the curvature radius of this arc is formed to be essentially the same as the radius of the steel ball118.

The center point of the steel ball118disposed within the fixed frame receiving portion113acan move in the area surrounded by the double dot and dash line A1inFIG. 14(a), as well as on the double dot and dash line A1itself. That is, when the center of the steel ball118moves on the double dot and dash line A1in the rolling area150, the surfaces of the steel ball118contact the fixed portion rolling area demarcation wall150a, and they become unable to move any further outward. At the same time, in the positionally restricted area152, the narrow fixed portion restricted area demarcation wall152agap causes the steel ball118to simultaneously contact the fixed portion restricted area demarcation wall152a. Therefore in the positionally restricted area152, the steel ball118can move only in the circle D direction in which the positionally restricted area152extends; movement of the steel ball118is restricted in the direction perpendicular to the circle D. That is, the area in which the center of the steel ball118can move in the positionally restricted area152is line-shaped; this line-shaped area essentially matches the circle D (FIG. 12)on which the fixed frame receiving portion113ais disposed.

In the meantime, the moving frame receiving portion115aformed on the moving frame114in correspondence to the fixed frame receiving portion113ahas essentially the same shape as the fixed frame receiving portion113a, and is furnished with a rolling area154and a positionally restricted area156(FIG. 15). Moreover, the rim of the rolling area154is demarcated by a moving portion rolling area demarcation wall154a, and the rim of the positionally restricted area156is demarcated by a moving portion restricted area demarcation wall156a. As shown inFIG. 12, the positionally restricted area156of moving frame receiving portion115aalso extends in a direction essentially tangential to the circle D, but extends in a direction opposite that of the positionally restricted area152of fixed frame receiving portion113a.

Note that while we have here explained the constitution of the fixed frame receiving portion113aand the moving frame receiving portion115a, the fixed frame receiving portion113band the moving frame receiving portion are constituted in exactly the same way, as shown inFIGS. 12 and 13. In the present embodiment the positionally restricted area is formed in a straight line so as to extend in a direction essentially tangential to the circle D, but in cases where the positionally restricted area is long, the positionally restricted area can also be constituted in an arc shape extending along the circle D. In the present Specification, the words “extending in a direction essentially tangential to a circle” shall be deemed to include both the form of a straight line extending in an essentially tangential direction, and the form of an essentially arc shape extending along a circle.

Next, referring toFIG. 15, we discuss the relative positions of the fixed frame receiving portion113aand the moving frame receiving portion115a, as well as the area in which the steel ball118can roll.

First, as shown inFIG. 15(a), in the image blur compensation control operational center position, the rolling area150of fixed frame receiving portion113aand the rolling area154of moving frame receiving portion115aare in essentially a superimposed state. In this state, the center of the steel ball118can move in the overlapping portion between the area demarcated by the fixed portion rolling area demarcation wall150aof rolling area150surrounded by double dot and dash line A1, and the area demarcated by the rolling area154and surrounded by single dot and dash line A2. During the image blur compensation control operation, the center of the steel ball118moves within the portion overlapping between the double dot and dash line A1and the single dot and dash line A2as a result of the relative movement of the moving frame114with respect to the fixed frame112. InFIG. 15(a), for example, when the moving frame114is moved to the lowermost position relative to the fixed frame112, the moving frame receiving portion115ais moved to the position shown by a dotted line in the figure, at which point the steel ball118is also moved to the position shown by the dotted line.

Next, when the moving frame114is moved to the locking position, the moving frame114is moved clockwise (to the right inFIG. 15) from the image blur compensation control operational center position. This causes the portion overlapping between the double dot and dash line A1in the fixed frame receiving portion113aand the single dot and dash line A2in the moving frame receiving portion115ato narrow as shown inFIG. 15(b), such that the area within which the steel ball118can move gradually narrows.

Next, as shown inFIG. 15(c), when the moving frame114is moved to the locking position, the portion overlapping between the double dot and dash line A1and the single dot and dash line A2becomes a line-shaped area. In this state, that is, the steel ball118is positioned at the fixed frame receiving portion113apositionally restricted area152and is simultaneously positioned at the moving frame receiving portion115apositionally restricted area156. For this reason movement of the moving frame receiving portion115ain the radial direction of circle D (the vertical direction as seen inFIG. 15)relative to the fixed frame receiving portion113ais blocked by the steel ball118, and only movement of the moving frame receiving portion115ain the circular direction (the horizontal direction as seen inFIG. 15) is permitted.

Here, as shown inFIG. 13, when the moving frame114is moved to the locking position, the fixed frame receiving portion113band the moving frame receiving portion115bare both moved to a similar relative position as that shown inFIG. 15(c). Therefore movement by the moving frame receiving portion115bin the circle D radial direction relative to the fixed frame receiving portion113bis blocked by the steel ball118, and only circular direction movement of the moving frame receiving portion115bis allowed. For the moving frame114, that is, movement in the circle D radial direction is restricted by two points on the moving frame receiving portions115aand115b. This results in restricted translational movement of the moving frame114in the locking position, such that only rotation centered on the optical axis of the image blur compensation lens116is allowed. In the locking position, the optical axis of the image blur compensation lens116attached to the moving frame114coincides with the optical axis of the other imaging lenses8.

Next, referring toFIG. 16, we discuss the constitution of the fixed frame receiving portion113c.

As shown inFIG. 16(a), the fixed frame receiving portion113chas a rolling area158shaped as approximately a circular depression, and a fixed portion adjustment area160formed continuously with this rolling area158. The rim of the rolling area158is demarcated by a fixed portion rolling area demarcation wall158a. As shown inFIG. 16(c), the rolling area158is a relatively broad area, the bottom surface of which is to be formed flat; in this area the steel ball118can roll in any desired direction. At the same time, a fixed portion adjustment area160is formed to connect from the rolling area158as a narrow width area extending in the circular tangent direction. The fixed portion adjustment area160inclines outward relative to the tangential direction of a circle D (FIG. 12)centered on the optical axis, and extends so as to intersect the circle D. The rim of the fixed portion adjustment area160is demarcated by the fixed portion adjustment area demarcation wall160a. As shown inFIG. 16(b), the fixed portion adjustment area160is formed such that its bottom surface is arc-shaped in section, and the curvature radius of this arc is formed to be essentially the same as the radius of the steel ball118.

The center point of the steel ball118disposed within the fixed frame receiving portion113ccan move in an area surrounded by the double dot and dash line A1inFIG. 16(a), and on the double dot and dash line A1itself. That is, in the rolling area158, when the center of the steel ball118rolls up to the double dot and dash line A1, the surface of the steel ball118contacts the fixed portion rolling area demarcation wall158a, and cannot move any further out. At the same time, in the fixed portion adjustment area160, the fixed portion adjustment area demarcation wall160agap is narrow, therefore the steel ball118simultaneously contacts the fixed portion adjustment area demarcation wall160aon both sides. Hence in the fixed portion adjustment area160, the steel ball118can move only in the direction in which the fixed portion adjustment area160extends, and movement of the steel ball118in the direction perpendicular thereto is restricted. That is, the area in which the center of the steel ball118can move in the fixed portion adjustment area160is line-shaped, and this line-shaped area intersects the circle D (FIG. 12)on which the fixed frame receiving portion113cis disposed.

At the same time, a moving frame receiving portion115c, corresponding to a fixed frame receiving portion113cand formed on the moving frame114, is formed to have essentially the same shape as the fixed frame receiving portion113c, and is furnished with a rolling area162and a moving portion adjustment area164(FIG. 17). Furthermore, the rim of the rolling area162is demarcated by a moving portion rolling area demarcation wall162a, and the rim of the moving portion adjustment area164is demarcated by a moving portion adjustment area demarcation wall164a. Further, as shown inFIG. 12, the moving frame receiving portion115cmoving portion adjustment area164extends in a direction intersecting the circle D, but extends in the opposite direction to that of the fixed frame receiving portion113cfixed portion adjustment area160.

Next, referring toFIG. 17, we discuss the relative positions of the fixed frame receiving portion113cand the moving frame receiving portion115c, as well as the area in which the steel ball118can roll.

First, as shown inFIG. 17(a), at the image blur compensation control operational center position the rolling area158of fixed frame receiving portion113cand the rolling area162of moving frame receiving portion115care in an essentially superimposed state. In this state, the center of the steel ball118can move in the overlapping portion between the area demarcated by the fixed portion rolling area demarcation wall158aof rolling area158surrounded by the double dot and dash line A1and the area demarcated by rolling area162and surrounded by the single dot and dash line A2. During the image blur compensation control operation, the center of the steel ball118moves within the portion overlapping between the double dot and dash line A1and the single dot and dash line A2as a result of the relative movement of the moving frame114relative to the fixed frame112. InFIG. 17(a), for example, when the moving frame114is moved to the uppermost position relative to the fixed frame112, the moving frame receiving portion115cis moved to the position shown by the dotted line in the figure, at which point the steel ball118is also moved to the position shown by the dotted line.

Next, when the moving frame114is moved to the locking position, the moving frame114is moved clockwise (to the left inFIG. 17) from the image blur compensation control operational center position. This causes the portion overlapping between the double dot and dash line A1in the fixed frame receiving portion113cand the single dot and dash line A2in the moving frame receiving portion115cto narrow as shown inFIG. 17(b), such that the area in which the steel ball118can move gradually narrows.

Next, as shown inFIG. 17(c), when the moving frame114is moved to the locking position, the overlapping portion between the double dot and dash line A1and the single dot and dash line A2is the point of intersection thereof. That is, in this state the steel ball118is positioned at the fixed portion adjustment area160of fixed frame receiving portion113c, and at the same time is positioned at the moving portion adjustment area164of moving frame receiving portion115c. Therefore the position of the center of the steel ball118is limited to the intersection between the double dot and dash line A1in the fixed portion adjustment area160and the single dot and dash line A2in the moving portion adjustment area164. The position of the intersection between the double dot and dash line A1and the single dot and dash line A2changes according to the rotational position of the moving frame114relative to the fixed frame12.

As described above, in the locking position the moving frame114is restricted by the action of the fixed frame receiving portions113aand113band the moving frame receiving portions115aand115b, such that the optical axis of the image blur compensation lens116and the optical axis of the other imaging lenses8coincide. In the locking position, that is, the moving frame114is placed in a state whereby only rotation centered on the optical axis is allowed by the fixed frame receiving portions113aand113band the moving frame receiving portions115aand115b; the fixed frame receiving portion113cand the moving frame receiving portion115callow this rotation by changing the position of the intersection between the double dot and dash line A1and the single dot and dash line A2.

Also, since the double dot and dash line A1in the fixed portion adjustment area160and the single dot and dash line A2in the moving portion adjustment area164are oriented so as to intersect, there will always be a point of intersection between the double dot and dash line A1and the single dot and dash line A2even when a margin of error is included in the position and shape of the fixed frame receiving portion and the moving frame receiving portion. Therefore in the locking position it will not occur that no overlapping point between the fixed portion adjustment area160and the moving portion adjustment area164exists, or that the steel ball118cannot be simultaneously positioned within the fixed portion adjustment area160and the moving portion adjustment area164.

On this point, if in the present embodiment the fixed frame receiving portion113cand moving frame receiving portion115chave the same shape as the fixed frame receiving portion113aand the moving frame receiving portion115a, and a position restricting area is provided, then in the locking position the distance from the optical axis to each steel ball118will be limited by three points. Therefore when a margin of error is included in the position and shape of the fixed frame receiving portion and the moving frame receiving portion, or when dimensional distortions arise due to thermal expansion, it becomes impossible to simultaneously sandwich each steel ball118within three sets of position restricting areas. In such cases, it may occur that the moving frame114floats up from the fixed frame12without any of the steel balls118being contained at the appropriate locations within positionally restricted areas, and the image blur compensation lens116locking position slips.

Next we discuss the action which moves the moving frame114to the locking position.

First, when the camera hand vibration function startup switch (not shown) is turned off, or when the camera power supply switch (not shown) is turned off, the locking position movement means37(FIG. 8) built into the controller36moves the moving frame114toward the locking position.

As a result, the fixed frame receiving portions113a,113b, and113c, and the moving frame receiving portions115a,115b, and115cshift from the state shown inFIGS. 15(a) and17(a) to the state shown inFIGS. 15(b) and17(b). The controller36sends a signal to the solenoid (not shown) connected to the locking hook117(FIG. 12), energizing it and thereby rotating the locking hook117to the position shown by the imaginary line.

When the moving frame114is rotated further clockwise and reaches the position shown inFIG. 13, the steel balls118sandwiched by the fixed frame receiving portions113aand113band the moving frame receiving portions115aand115bbecome respectively sandwiched between the positionally restricted areas152and156. In the meantime, the steel ball118sandwiched between fixed frame receiving portion113cand the moving frame receiving portion115calso becomes sandwiched between the fixed portion adjustment area160and the moving portion adjustment area164.

When the moving frame114reaches the position shown inFIG. 13, the controller36sends a signal to the solenoid (not shown) and stops energizing it, so that the locking hook117is turned to the position shown by the solid line inFIG. 3. This results in engagement of the locking hook117attached to the fixed frame112with the locking protuberance117aprovided on the moving frame114. Here, in the state shown inFIG. 13, movement of the moving frame114relative to the fixed frame112is restricted to rotation only by the action of the positionally restricted areas152and156and the steel ball118sandwiched therebetween. In this state, engaging of the locking hook117with the locking protuberance117aresults in restriction of the rotation of the moving frame114and locking of translational and rotational movement by the moving frame114.

In the locking position, each steel ball118is respectively sandwiched between the positionally restricted areas152and156, which are formed to have a curved surface with essentially the same curvature radius as that of the steel ball118, and between the fixed portion adjustment area160and the moving portion adjustment area164. Therefore since the contact surface area between each steel ball118and the fixed frame receiving portion and moving frame receiving portion becomes comparatively broad, the pressure acting on the fixed frame receiving portion and the moving frame receiving portion is reduced when a shock force acts on the camera.

Furthermore, because in the locking position each steel ball118is respectively sandwiched between the positionally restricted areas152and156and between the fixed portion adjustment area160and the moving portion adjustment area164, each steel ball118is locked within the fixed frame receiving portion and the moving frame receiving portion, and there is no looseness. Also, the position of the steel ball118in the locking position is restricted within the positionally restricted area and the adjustment area, and is essentially uniquely positioned.

Next, when the moving frame114is restored from the locking position to the operational center position, the controller36sends a signal to the solenoid (not shown) and energizes it, thereby rotating the locking hook117to the position shown by imaginary lines inFIG. 13. This results in a release of the engagement between the locking hook117and the locking protuberance117a. Next, the locking position movement means37outputs a lens position command signal causing the moving frame114to rotate by a predetermined angle in the counterclockwise direction, such that the moving frame114is restored to the image blur compensation control operational center position shown inFIG. 12. The controller36then further sends a signal to the solenoid (not shown) and stops energizing it, causing the locking hook117to rotate to the position shown by the solid line inFIG. 12.

Here, in the locking position, the position of each steel ball118is essentially uniquely determined. By rotating the moving frame114from the locking position counterclockwise by a predetermined angle, the position to which each steel ball118is moved by rolling is also essentially uniquely determined. The position of the steel balls118within the rolling area when the actuator110is restored to the operational center position can therefore be set at an appropriate position.

Using the camera of the second embodiment of the present invention, at the locking position the steel balls are sandwiched in two positionally restricted areas such that the movement of the moving frame is restricted by two points in the radial direction of a circle centered on the optical axis, and translational movement of the moving frame is locked. Without providing any special members, that is, translational movement of the moving frame can be locked simply by providing a positionally restricted area in the steel ball receiving portion. The moving frame can by this means be locked without increasing the outside diameter of the actuator.

Using the camera of the second embodiment of the present invention, a single ball is sandwiched between a fixed portion adjustment area and a movable portion adjustment area, therefore the distance between the steel ball sandwiched between these elements and the optical axis may be varied. As a result, positional and dimensional errors in the positionally restricted area can be allowed, while positioning of the steel balls sandwiched between the fixed portion adjustment area and the moving portion adjustment area is reliably performed.

Additionally, when using the camera of the second embodiment of the present invention, the positionally restricted area comprises a curved surface having essentially the same curvature radius as the surface of the steel balls, such that the contact surface area where the positionally restricted area contacts the steel balls can be made broad, and contact pressure reduced.

We have discussed above preferred embodiments of the present invention, but a number of variations can also be added to the embodiments described above. In particular, the present invention was applied to a film camera in the embodiments described above, but the present invention can also be applied to still image or moving image capture cameras of any desired type, such as digital cameras, video cameras, and the like.

In the embodiments described above, the moving frame was supported by three steel balls, but three or more steel balls could also be used.

Furthermore, in the embodiment described above, rotation of the moving frame was locked by the locking hook, but as a rotation locking means it would also be acceptable to provide a shaft extending from the fixed frame to the moving frame when locked, with a concavity or a hole to receive this shaft.