Driving device capable of properly restricting translational movement and rotational movement, image capturing apparatus, and method of controlling driving device

A driving device that has a movable part which is translationally and rotationally movable within a plane with respect to a fixed part and is capable of properly restricting the translational movement and the rotational movement of the movable part while preventing the movable part from protruding outward. The driving device includes an actuator that drives the movable part, a first restricting unit configured to restrict translational movement of the movable part, and a second restricting unit configured to restrict rotational movement of the movable part. The second restricting unit is arranged at a location more remote from a center of rotation of the movable part with respect to the fixed part than the first restricting unit.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a driving device, an image capturing apparatus equipped with the driving device, and a method of controlling the driving device.

Description of the Related Art

There is known a driving device that moves a movable part within a plane with respect to a fixed part, and there is conventionally employed a system called VCM (voice coil motor) as a component configured to generate a driving force for driving the movable part. In the VCM system, a magnet is arranged on one of the movable part and the fixed part and a coil is arranged on the other of them, and a driving force is generated by energizing the coil in a magnetic circuit formed by the magnet.

As an example of application of this driving device, there may be mentioned a shake correction mechanism mounted on an image capturing apparatus. In the shake correction mechanism, an image sensor or a shake correction lens is mounted on a movable part, and based on a shake amount detected by a predetermined sensor, the movable part is driven so as to cancel out a detected shake. Particularly, the shake correction mechanism having the image sensor mounted on the movable part is higher in shake correction performance than the shake correction mechanism having the shake correction lens mounted on the movable part in that it is possible to correct rotation about an axis orthogonal to an imaging surface of the image sensor (image capturing optical axis).

In the driving device of this type, a restricting section is provided to prevent drop-off of the movable part from the fixed part. In a driving device in which the movable part is rotatable about the image capturing optical axis, such as the shake correction mechanism of the image capturing apparatus, this restricting section is required to be arranged at a location where it does not interfere with the rotational movement of the movable part. Further, in general, in such a shake correction mechanism, a plurality of balls are arranged between the movable part and the fixed part to reduce contact resistance, whereby it is possible to perform smooth driving. For the arrangement of the balls, an enclosure for preventing the balls from dropping off in a direction parallel to a rolling surface is provided. Further, the movable part and the fixed part are provided with an abutting portion and an abutted portion for restricting the movement of the movable part with respect to the fixed part, respectively.

For example, Japanese Patent No. 3969927 discloses a technique for performing, before photographing, an operation of resetting the position of balls in a shake correction device that moves a lens group by using a two-axis driving device, to thereby prevent the balls from being brought into contact with an enclosure during actual use. Further, Japanese Patent No. 3969927 describes a movable mechanical end provided for limiting the movement of the movable part.

Incidentally, a user sometimes performs photographing using an image capturing apparatus while walking, and here, a shake occurring in this situation is referred to as the “walking shake”. The walking shake becomes larger in shake amount than a shake occurring in a case where a user performs photographing in a state standing still, and hence there is a demand for a shake correction device that is capable of canceling out a larger shake amount.

The shake correction device of the image capturing apparatus can correct a large shake amount by increasing a movement amount of the movable part holding the image sensor or the shake correction lens with respect to the fixed part. Particularly, when the walking shake occurs, a shake amount of rotation about the image capturing optical axis tends to become large, and hence by increasing a movement amount by which the movable part is rotatable about the image capturing optical axis (as the central axis) with respect to the fixed part, it is possible to increase the effect of shake correction.

Here, the shake correction device described in Japanese Patent No. 3969927 is configured to allow the movable part to translationally move only within a plane orthogonal to the optical axis as described above, but is not configured to allow the movable part to rotationally move within the plane. Further, Japanese Patent No. 3969927 does not disclose a specific configuration of the movable mechanical end for limiting the movement of the movable part. Further, if the rotational movement amount of the movable part with respect to the fixed part is increased, an amount by which the movable part protrudes outward increases, which can result in an increase of the size of the image capturing apparatus. To avoid this inconvenience, for the driving device having the movable part that is translationally and rotationally movable, a configuration is required in which the translational movement and the rotational movement of the movable part are properly restricted while preventing the movable part from protruding outward.

SUMMARY OF THE INVENTION

The present invention provides a driving device that has a movable part which is translationally and rotationally movable within a plane with respect to a fixed part, wherein the translational movement and the rotational movement of the movable part can be properly restricted while preventing the movable part from protruding outward, an image capturing apparatus including the driving device, and a method of controlling the driving device.

In a first aspect of the present invention, there is provided a driving device including a fixed part, a movable part that is arranged such that the movable part is translationally movable and is rotatable within a plane with respect to the fixed part, an actuator that drives the movable part, a first restricting unit configured to restrict translational movement of the movable part by abutment between the movable part and the fixed part, and a second restricting unit configured to restrict rotational movement of the movable part by abutment between the movable part and the fixed part, wherein the second restricting unit is arranged at a location more remote from a center of rotation of the movable part with respect to the fixed part than the first restricting unit.

In a second aspect of the present invention, there is provided an image capturing apparatus including a fixed part, a movable part that is arranged such that the movable part is translationally movable and is rotatable within a plane with respect to the fixed part, an actuator that drives the movable part, a first restricting unit configured to restrict translational movement of the movable part by abutment between the movable part and the fixed part, a second restricting unit configured to restrict rotational movement of the movable part by abutment between the movable part and the fixed part, an image sensor that is held by the movable part, and a blur corrector configured to control driving of the movable part so as to cancel out the image blur, wherein the second restricting unit is arranged at a location more remote from a center of rotation of the movable part with respect to the fixed part than the first restricting unit, and wherein the image sensor is held by the movable part such that an imaging surface of the image sensor is translationally movable and rotatable within a plane orthogonal to an image capturing optical axis of the image capturing apparatus.

In a third aspect of the present invention, there is provided a method of controlling a driving device including a movable part which is translationally movable and rotatable within a plane with respect to a fixed part, and a plurality of rolling members arranged between the fixed part and the movable part, and having the plurality of rolling members arranged inside enclosures provided on the movable part, respectively, such that the rolling members are prevented from being brought into abutment with inner walls of the enclosures, within a driving control range used when actually driving the driving device, including translationally moving the movable part without rotationally moving the movable part, such that a circle having a predetermined radius from the center of rotation is drawn, and rotationally moving the movable part about the center of rotation through a predetermined rotational angle after translationally moving the movable part, and rotating, when rotationally moving the movable part, the movable part in a first rotational direction about the center of rotation of the movable part and a second rotational direction opposite to the first rotational direction through the same angle, respectively.

According to the present invention, in the driving device that has the movable part which is translationally and rotationally movable within a plane with respect to the fixed part, it is possible to properly restrict the translational movement and the rotational movement of the movable part while preventing the movable part from protruding outward.

DESCRIPTION OF THE EMBODIMENTS

An embodiment of the present invention will now be described in detail below with reference to the accompanying drawings. In the present embodiment, a configuration in which a driving device according to the present invention is applied to an image blur correction device of an image capturing apparatus will be described.

FIG.1is a schematic diagram of the image capturing apparatus, denoted by reference numeral10, according to the embodiment of the present invention. The image capturing apparatus10is a so-called mirrorless digital camera and has an image capturing apparatus body10a(hereinafter referred to as the “body10a”) and a lens barrel10bwhich is removably attached to the body10a.

The body10aincludes an image sensor11having an imaging surface11a, a base member13c, a body-side mount member13a, a camera controller14, a first shake correction controller15a, a first vibration detection section16a, an image processor17, and a first blur correction unit (blur corrector)20. The lens barrel10bincludes an image capturing optical system12including a shake correction lens12b, a lens-side mount member13b, a second shake correction controller15b, a second vibration detection section16b, and a second blur correction unit (blur corrector)60.

A virtual light ray as a representative of a light flux irradiated onto the imaging surface11aof the image sensor11through the image capturing optical system12is referred to as the “image capturing optical axis12a” (hereinafter described as the “optical axis12a”), and a plane orthogonal to the optical axis12ais referred to as the “optical axis orthogonal plane12c” (hereinafter described as the “optical axis orthogonal plane12c”). The optical axis12apasses through the center of the imaging surface11aand is orthogonal to the imaging surface11a.

To make clear the arrangement and positional relationship of the components of the image capturing apparatus10within the image capturing apparatus10, an X direction, a Y direction, and a Z direction, which are orthogonal to one another, are defined as shown inFIG.1. The Z direction is a direction parallel to the optical axis12a, the X direction is a width direction of the image capturing apparatus10, and the Y direction is a height direction of the image capturing apparatus10. In a case where the X direction and the Z direction are both in a horizontal plane, the Y direction is a vertical direction, and the optical axis orthogonal plane12cis an X-Y plane.

The image sensor11is, specifically, a CMOS image sensor or CCD image sensor, for example, and is arranged such that the imaging surface11afaces toward an object (toward the lens barrel10b) and is orthogonal to the optical axis12a. The image sensor11generates image signals by photoelectrically converting an optical image of an object formed on the imaging surface11aby the image capturing optical system12. The image signals generated by the image sensor11are subjected to a variety of processing operations performed by the image processor17to thereby be converted to image data, and the generated image data is stored in a memory (storage device), not shown. The camera controller14is an arithmetic unit in a main IC, not shown, and controls the overall operation of the image capturing apparatus10by receiving an input operation of a user via operating means, not shown.

The image capturing optical system12is formed by a lens group, a diaphragm, and so forth, none of which are shown, arranged within the lens barrel10b, and causes light reflected from an object, not shown, to form a an image on the imaging surface11aof the image sensor11. In the image capturing apparatus10, to arrange the image sensor11with high positional accuracy with respect to the optical axis12a, the image sensor11is mounted on the base member13cprovided in the body10a, and the lens barrel10bis also coupled to the base member13c. More specifically, the image sensor11is mounted on the base member13cvia the first blur correction unit20, and the lens barrel10bis coupled to the base member13cvia the lens-side mount member13band the body-side mount member13a.

The first blur correction unit20corrects an image blur caused by a shake (including vibration and swing) of the image capturing apparatus10by moving the image sensor11in a desired direction in the optical axis orthogonal plane12cor rotating the same in the optical axis orthogonal plane12c, thereby making it possible to obtain a clear object image. More specifically, when a shake has caused a change in posture of the image capturing apparatus10during image capturing, imaging positions of an object light flux on the imaging surface11aof the image sensor11change, whereby a blur occurs in an image obtained through the image sensor11. At this time, in a case where the change in posture of the image capturing apparatus10is sufficiently small, the changes in the imaging positions are uniform within the imaging surface11aand can be regarded to be caused by the translational or rotational movement (imaging surface shake) in the optical axis orthogonal plane12c. Therefore, by translationally moving or rotating the image sensor11in the optical axis orthogonal plane12cso as to cancel out this imaging surface shake, it is possible to obtain a clear object image in which the image blur has been corrected. Note that the image capturing apparatus10may be configured such that when moving the image sensor11in a direction parallel to the imaging surface, the image sensor11can be moved in a direction orthogonal to the imaging surface (an optical axis direction, i.e. a direction along the optical axis12a).

Similarly, the second blur correction unit60corrects an image blur caused by a shake of the image capturing apparatus10by moving the shake correction lens12bin the optical axis orthogonal plane12cin a direction in which the imaging surface shake can be cancel outed, thereby making it possible to obtain a clear object image. Note that the principle of shake correction, i.e. blur correction performed by moving the image sensor11or the shake correction lens12bis known, and hence detailed description thereof is omitted. Further, the image forming apparatus may be configured such that when moving the shake correction lens12bin the optical axis orthogonal direction, the shake correction lens12bcan be moved in the optical axis direction.

The first blur correction unit20is roughly comprised of a fixed part, a movable part, and a plurality of driving-force generation sections. The fixed part is fixed to the base member13c, and the movable part holds the image sensor11. Further, the movable part is supported by the fixed part with three degrees of freedom, and is translationally movable relative to the fixed part in a desired direction in the optical axis orthogonal plane12cand is also rotatable in the optical axis orthogonal plane12c. That is, the first blur correction unit20is configured as a driving device (so-called XYθ stage) that is capable of controlling three-axis driving and is capable of moving the image sensor11in a desired direction in the optical axis orthogonal plane12cand rotating the same in the optical axis orthogonal plane12c.

The second blur correction unit60is roughly comprised of a fixed part, a movable part, and a plurality of driving-force generation sections. The fixed part is fixed to a casing of the lens barrel10b, not shown, and the movable part holds the shake correction lens12b. Further, the movable part is supported by the fixed part with two degrees of freedom and is movable relative to the fixed part in a desired direction in the optical axis orthogonal plane12c. That is, the second blur correction unit60is configured as a driving device (so-called XY stage) that is capable of controlling two-axis driving and is capable of moving the shake correction lens12bin a desired direction in the optical axis orthogonal plane12c.

The first vibration detection section16aand the second vibration detection section16bare each vibration detecting means for detecting an angular speed, an acceleration, and so forth, of the image capturing apparatus10in each direction, as shake information of the image capturing apparatus10, and is, more specifically, implemented e.g. by a gyro sensor or an acceleration sensor. Further, the first shake correction controller15aand the second shake correction controller15beach calculate an angle change amount and a movement amount of the image capturing apparatus10in each direction as the shake information by integrating angular speeds and accelerations, detected by the first vibration detection section16aand the second vibration detection section16b.

Further, the first shake correction controller15acalculates a movement target value of the image sensor11based on the shake information detected by the first vibration detection section16aand controls the movement of the image sensor11by controlling driving of the first blur correction unit20. Similarly, the second shake correction controller15bcalculates a movement target value of the shake correction lens12bbased on the shake information detected by the second vibration detection section16band controls the movement of the shake correction lens12bby controlling driving of the second blur correction unit60.

Note that the image capturing apparatus10may be configured to include only the first blur correction unit20. In a case where the second blur correction unit60is not included, the shake correction lens12bis basically not required. Therefore, the image capturing optical system12of the lens barrel10bis designed such that the desired optical characteristics can be obtained with a lens configuration without having the shake correction lens12b.

Next, a description will be given of details of the first blur correction unit20as an embodiment of the driving device according to the present invention. Note that the configuration of the first blur correction unit20is not applied to the second blur correction unit60. This is because as is clear from the configuration of the first blur correction unit20, described hereinafter, in a case where the image sensor11included in the first blur correction unit20is simply replaced by the shake correction lens12b, part of a light flux transmitting through the shake correction lens12bis blocked. Therefore, as the second blur correction unit60, there is used not the driving device according to the present invention, but a driving device that does not drive the movable part20bfor rotation, for example, the driving device applied to the lens barrel, which is described in the above-mentioned Japanese Patent No. 3969927.

FIGS.2A and2Bare exploded perspective views of the first blur correction unit20, andFIG.2AandFIG.2Bdiffer from each other in a direction of viewing the first blur correction unit20. The first blur correction unit20includes the fixed part, denoted by reference numeral20a, and the movable part, denoted by reference numeral20b. Note thatFIGS.2A and2Bshow the movable part20bin an unexploded state, and the fixed part20ain an exploded state.

The fixed part20ahas a fixed member21, a rear yoke22, a first rear magnet group23a, a second rear magnet group23b, and a third rear magnet group23c. The fixed member21is formed with a first opening21a, a second opening21b, and a third opening21c. The first rear magnet group23a, the second rear magnet group23b, and the third rear magnet group23care fixed to the rear yoke22e.g. with adhesive and are arranged such that the first rear magnet group23a, the second rear magnet group23b, and the third rear magnet group23care surrounded by the first opening21a, the second opening21b, and the third opening21c, respectively.

In the present embodiment, as the first rear magnet group23a, the second rear magnet group23b, and the third rear magnet group23c, there are used magnet groups each formed by two magnets that are magnetized in the optical axis direction (Z direction) and are arranged such that the two magnets generate magnetic fields in opposite directions. However, this is not limitative, but there may be used single magnets each magnetized to the two poles.

The fixed part20afurther has a first columnar member24a, a second columnar member24b, a third columnar member24c, a front yoke25, a first front magnet26a, a second front magnet26b, and a third front magnet26c. The front yoke25is fixed to the fixed member21with screws via the first columnar member24a, the second columnar member24b, and the third columnar member24c. The first front magnet26a, the second front magnet26b, and the third front magnet26care fixed to the front yoke25e.g. with adhesive, respectively.

In the present embodiment, as the first front magnet26a, the second front magnet26b, and the third front magnet26c, there are used single magnets each magnetized to two poles. However, this is not limitative, but magnet groups each formed by two magnets that are magnetized in the optical axis direction and are arranged such that the two magnets generate magnetic fields in opposite directions.

The first rear magnet group23aand the first front magnet26aform a first magnetic circuit. Similarly, the second rear magnet group23band the second front magnet26bform a second magnetic circuit, and the third rear magnet group23cand the third front magnet26cform a third magnetic circuit.

The fixed part20afurther has a first restricting member28, a second restricting member29, and a cover30. The rear yoke22has a first restricting portion22a, and the front yoke25has a second restricting portion25a(protruding portion) protruding toward the movable part20b. The movement of the movable part20bis restricted in a predetermined range in the optical axis orthogonal plane12cby the first restricting member28, the second restricting member29, the first restricting portion22a, the second restricting portion25a, the first columnar member24a, the second columnar member24b, and the third columnar member24c(described in detail hereinafter). Abutting portions of the respective components for restricting the movement of the movable part20bare each provided with a cushioning member, such as rubber, for absorbing a shock of abutment so as to avoid breakage and reduce collision noise. The cover30prevents a flexible print substrate, such as a driving FPC35, described hereinafter, and the rear yoke22from being brought into contact with each other. Although described in detail hereinafter, balls36are arranged between the movable part20band the fixed member21.

FIGS.3A and3Bare exploded perspective views of the movable part20b, andFIG.3AandFIG.3Bdiffer from each other in a direction of viewing the movable part20b. The movable part20bhas an image sensor-holding member31and the image sensor11. The image sensor11is fixed to the image sensor-holding member31with adhesive, but details thereof will be described hereinafter. Further, the movable part20bhas a mask32a, an infrared absorbing filter32b, an optical lowpass filter32c, and a vibration unit32f. The mask32a, the infrared absorbing filter32b, and the optical lowpass filter32care held by a holder member32dand a holder sheet metal32e, and are fixed to the image sensor11e.g. with an adhesive member. The mask32aprevents unnecessary light from entering front outside the photographing optical path. The optical lowpass filter32creduces moire generated by a repeated pattern of an object. The vibration unit32fis provided on the optical lowpass filter32cso as to eliminate foreign material, such as dust, attached to the surface of the optical lowpass filter32c, by vibrating the optical lowpass filter32c. Note that the principle and control of elimination of foreign material, performed by the vibration unit32f, are known, and hence detailed description thereof is omitted.

The movable part20bincludes a first coil33a, a second coil33b, a third coil33c, and the driving FPC35. The driving FPC35is fixed to the image sensor-holding member31e.g. with adhesive, and is arranged such that the driving FPC35overlaps the first coil33a, the second coil33b, and the third coil33c, on a plane projected in the optical axis direction (on an X-Y plane as viewed from the Z direction).

The image sensor-holding member31has a first recess31a, a second recess31b, and a third recess31c. The first coil33a, the second coil33b, and the third coil33care arranged in the first recess31a, the second recess31b, and the third recess31c, respectively.

The first magnetic circuit and the first coil33aform a VCM as a first actuator, the second magnetic circuit and the second coil33bform a VCM as a second actuator, and the third magnetic circuit and the third coil33cform a VCM as a third actuator.

The Lorentz force is generated in a direction which is orthogonal to the direction of the magnetic field generated by the first magnetic circuit in the optical axis direction and a direction in which electric current flows in the first coil33a, and a resultant force direction of the Lorentz force changes according to the energization direction of the first coil33a. Similar Lorentz forces are generated in the second magnetic circuit and the second coil33b, and also in the third magnetic circuit and the third coil33c, respectively. The first actuator and the second actuator generate respective forces (driving forces) substantially in parallel to the X direction, whereby a translational force in the X direction is generated by the sum of the respective forces, and a rotational force about the optical axis is generated by a difference between the respective forces. The third actuator generates a translational force in the Y direction. Comparison of the position of the first restricting portion22aand the positions of the first to third actuators shows that the first restricting portion22ais disposed at a location closer to the center of rotation of the movable part20bwith respect to the fixed member21than the first to third actuators. Note that the system of the actuator is not limited to the VCM, but a vibration actuator or the like may be used.

The driving FPC35has a first detector35a, a second detector35b, and a third detector35c, mounted thereon. The first detector35a, the second detector35b, and the third detector35care arranged inside the first coil33a, the second coil33b, and the third coil33c, respectively. The first detector35a, the second detector35b, and the third detector35care e.g. hall elements. The first detector35adetects a magnetic force of the first magnetic circuit, and the first shake correction controller15acalculates positional information of the movable part20bin the optical axis orthogonal plane12cwith respect to the fixed part20a(specifically, a position and an angle about the optical axis) based on a result of detection by the first detector35a. The same is applied to the second detector35band the third detector35c.

The first coil33a, the second coil33b, and the third coil33care electrically connected to the driving FPC35, and the first shake correction controller15acontrols the magnitude of electric current caused to flow in each coil via the driving FPC35. That is, the first shake correction controller15acontrols the driving of the movable part20busing feedback control, based on a difference between the movement target value of the image sensor11calculated based on the shake information detected by the first vibration detection section16aand the current position of the image sensor11, detected by the hall elements.

The movable part20bis urged against the fixed member21as a component of the fixed part20aby a suction force generated between the rear yoke22and a thrust magnet39due to a magnetic force of the thrust magnet39via the balls36(seeFIGS.2A and2B) which are rolling members. In other words, the rear yoke22and the thrust magnet39form an urging section for urging the movable part20bagainst the fixed part20a. Note that, to generate the suction force between the rear yoke22and the thrust magnet39, the rear yoke22is required to be a magnetic body (member formed of a magnetic material). Details of the urging section will be described hereinafter.

The balls36are arranged inside a first enclosure31d, a second enclosure31e, and a third enclosure31f, formed in the image sensor-holding member31, respectively. Although described in detail hereinafter, the balls36roll when the movable part20bmoves in the optical axis orthogonal plane12cwith respect to the fixed part20afor shake correction, and hence a load is hardly generated by friction between the balls36, and the image sensor-holding member31and the fixed member21. Further, the movement of the movable part20bin a direction opposite to the direction in which the urging section formed by the rear yoke22and the thrust magnet39urges the movable part20bis restricted by the front yoke25and the first restricting member28. Therefore, even when an external force for separating the movable part20bfrom the fixed member21(moving the movable part20btoward the lens barrel10b) is applied, e.g. by an impact applied to the image capturing apparatus10, the movable part20bis prevented from dropping off from the fixed part20a.

The movable part20bhas a connection member38, and the connection member38is bridged to an opening31iof the image sensor-holding member31and is fixed to the image sensor-holding member31with screws45at opposite ends (in the X direction) across the optical axis12a. The connection member38is formed with abutting portions38aas protrusions protruding toward the −Z side of the optical axis direction, at two locations, and the two abutting portions38aare inserted in two holes formed in the first restricting portion22aof the rear yoke22, respectively. Although described in detail hereinafter, the translational movement of the movable part20bin the optical axis orthogonal plane12cis restricted within a fixed range by the abutment between the outer peripheral surface of each abutting portion38aand a wall surface (inner wall) of the associated hole of the first restricting portion22a. Position restricting means for restricting the position of the movable part20b, formed by the abutting portions38aand the first restricting portion22a, is referred to as the first restricting means as deemed appropriate. Note that the holes as the first restricting portion22aand the protrusions as the abutting portions38aare only required to be provided such that one of each hole and each protrusion is provided in or on the fixed part20aand the other is provided in or on the movable part20b. That is, the protrusions may be formed on the fixed part20a, and the holes may be formed in the movable part20b.

The thrust magnet39and a thrust yoke40are fixed to the connection member38e.g. with adhesive, and the thrust magnet39is magnetized in the optical axis direction. Note that as the thrust magnet39, a magnet magnetized to the two poles such that magnetic fields different from each other in direction are arranged in the Y direction can be used, but a magnet magnetized to a single pole can be used as well.

The urging section formed by the rear yoke22and the thrust magnet39is arranged inside a triangle formed by the three balls36arranged inside the first enclosure31d, the second enclosure31e, and the third enclosure31f, respectively. Consequently, it is possible to generate the urging forces for the respective balls36in a well balanced manner.

Next, the configuration for restricting the relative position of the movable part20bwith respect to the fixed part20ain the optical axis orthogonal plane12cwill be described in detail with reference toFIGS.4to7. First, a general behavior of a point at a predetermined position on a plane as the point moves on the plane will be described with reference toFIGS.4and5for ease of understanding the behavior of the movable part20b.

FIG.4is a diagram useful in explaining translational movement and rotational movement of a physical object on a plane using a point O as a reference. InFIG.4, a position P0is a position of the physical object existing on the point O, a position P1is a position separated from the point O by a predetermined distance, and a position P2is a position more remote from the point O than the position P1. Positions moved by rotating the positions P1and P2about the point O in a counterclockwise direction through an angle θ are positions P1′ and P2′. Further, it is assumed that the physical object can translationally move in a desired direction on the plane by a distance d wherever the object exists on the plane. A range R1indicates a translationally movable range of the physical object at the position P1, and a range R2indicates a translationally movable range of the physical object at the position P2. Similarly, a range R1′ indicates a translationally movable range of the physical object at the position P1′, and a range R2′ indicates a translationally movable range of the physical object at the position P2′.

The physical object can rotationally move on an arc having the point O as the center through an angle θ. That is, the physical object at the position P1(or the position P1′) can rotationally move between the position P1and the position P1′, on an arc having the point O as the center and passing the position P1and the position P1′. Similarly, the physical object at the position P2(or the position P2′) can rotationally move between the position P2and the position P2′, on an arc having the point O as the center and passing the position P2and the position P2′.

Therefore, the range within which the physical object at the position P1can move is a range R1max which is a path of the range R1rotated about the point O through the angle θ. Similarly, the range within which the physical object at the position P2can move is a range R2max which is a path of the range R2rotated about the point O through the angle θ. Note that the range R1max can be said as a range within which the physical object at the position P1′ can move, and similarly, the range R2max can be said as a range within which the physical object at the position P2′ can move.

In the ranges R1max and R2max, the maximum movement amounts by which the object can move in rotational movement through the angle θ and the translational movement are d1max and d2max, respectively, and the maximum movement angles at which this maximum movement amounts can be realized only by the rotational movement about the point O are θ1max and θ2max. Then, as is clear fromFIG.4, d1max<d2max and θ1max>θ2max hold. Thus, as the distance from the point O as the center of rotation is larger, the maximum movement amount dmax by which the object can move in the rotational movement and the translational movement becomes larger, and the maximum movement angle θmax at which this maximum movement amount dmax can be realized by the rotational movement about the point O becomes smaller. The relationship between the distance from the point O (the center of rotation) and dmax and θmax is expressed as shown inFIG.5.

Inversely, it is clear fromFIG.5that if the translational movement and the rotational movement of the movable part20bare attempted to be restricted by the same restricting means, it is not easy to restrict the rotational movement with high accuracy at a position close to the optical axis12acorresponding to the point O. Further, at a position remote from the optical axis12a, the translational movement of the movable part20bcomes to be restricted to a movement amount largely exceeding the control range of the translational movement. In view of this, in the present embodiment, the movement range of the movable part20bis restricted as described below.

Next, the configuration for restricting the movement of the movable part20bin the optical axis orthogonal plane12cwith respect to the fixed part20awill be described with reference toFIGS.6A and6B, andFIGS.7A and7B.FIG.6Ais a rear view (view as viewed from the rear side of the image capturing apparatus10along the optical axis12a) useful in explaining the configuration for restricting the relative position of the movable part20bin the optical axis orthogonal plane12cwith respect to the fixed part20a. Note that inFIG.6A, to make clear the configuration for restricting the position of the movable part20b, illustration of the components involved in the position restriction of the movable part20bis simplified, and illustration of the components which are not directly involved in the position restriction is omitted. For example, for the first restricting portion22aof the rear yoke22, the first columnar member24a, the second columnar member24b, the third columnar member24c, the second restricting portion25aof the front yoke25, the first restricting member28, and the second restricting member29, only contact surfaces of these are illustrated to simplify the illustration.

The image sensor11included in the movable part20bis substantially rectangular, with its long side being substantially parallel to the X direction and its short side being substantially parallel to the Y direction. The movable part20bhas a plurality of abutting portions201to208. The abutting portions201to208are portions of the outer peripheral surface of the image sensor-holding member31as a component of the movable part20b. Further, some of the abutting portions201to208are provided in recesses or cutouts formed in the movable part20b(image sensor-holding member31) so as to reduce the amount of protrusion of the movable part20btoward the outside during driving the movable part20bfor rotation.

Although described in detail hereinafter with reference toFIGS.7A and7B, when the movable part20bis rotationally moved, the abutting portion201or the abutting portion202is brought into abutment with the first columnar member24a, and the abutting portion206or the abutting portion207is brought into abutment with the second restricting member29, according to the rotational direction. Further, the abutting portion203, the abutting portion204, the abutting portion205, and the abutting portion208are brought into abutment with the second restricting portion25a, the second columnar member24b, a protruding portion formed on the first restricting member28, and the third columnar member24c, respectively, according to the rotational direction of the movable part20b. Position restricting means for restricting the position of the movable part20b, formed by the abutting portions201to208, and the columnar members, the restricting portions, and the restricting members, associated with these abutting portions201to208, is referred to as the second restricting means as deemed appropriate.

Note that as described above, the connection member38connected to the movable part20bis formed with the abutting portions38aat two locations, and the outer peripheral surfaces of the abutting portions38aare brought into abutment with the inner peripheral walls of the first restricting portions22aof the rear yoke22, respectively, whereby the translational movement of the movable part20bis restricted. The abutting portions38aand the abutting portions201to208, and the restricting portions associated with these abutting portions are arranged so as not to be brought into abutment with each other when the first blur correction unit20is controlled by the first shake correction controller15a, and the movable part20bis driven within the movement range necessary for performing blur correction.

First, a case where the movable part20bperforms the translational movement in the optical axis orthogonal plane12cwithout rotation about the optical axis12a(rotation having the optical axis12aas the rotational center axis) will be described. In this case, the two abutting portions38aformed on the connection member38are brought into abutment with the first restricting portion22aof the rear yoke22, whereby the movement of the movable part20bis restricted. At this time, the abutting portions201to208which are more remote from the optical axis12athan the abutting portions38aare not brought into abutment with the associated members. That is, the translational movement of the movable part20bis restricted only by the two abutting portions38aand the first restricting portion22a.FIG.6Bshows an example of a state in which the movable part20bis not rotated about the optical axis12aand is translated in the Y direction.

Next, a case where the movable part20brotates in a clockwise direction in the optical axis orthogonal plane12c, as viewed from the rear side toward the front side of the image capturing apparatus10, will be described. In this case, one or a plurality of combinations of the abutting portion202and the first columnar member24a, the abutting portion203and the second restricting portion25a, the abutting portion207and the second restricting member29, and the abutting portion208and the third columnar member24care brought into abutment with each other, whereby the movement of the movable part20bis restricted. In a case where the movable part20btranslates in the optical axis orthogonal plane12cin addition to the rotation in the clockwise direction, the abutting portions38amay be brought into abutment with the first restricting portion22a. On the other hand, even when the rotation angle of the movable part20bbecomes the maximum in the clockwise direction from the state shown inFIG.6A, the abutting portions38aare not brought into abutment with the first restricting portion22a.FIG.7Ashows a state in which in a case where the rotation angle of the movable part20bbecomes the maximum in the clockwise direction from the state shown inFIG.6A, the movable part20bis stabilized by the plurality of restricting portions arranged to surround g the optical axis12a.

Next, a case where the movable part20brotates in the counterclockwise direction in the optical axis orthogonal plane12c, as viewed from the rear side toward the front side of the image capturing apparatus10, will be described. In this case, one or a plurality of combinations of the abutting portion201and the first columnar member24a, the abutting portion204and the second columnar member24b, the abutting portion205and the first restricting member28, and the abutting portion206and the second restricting member29are brought into abutment with each other, whereby the movement of the movable part20bis restricted. In a case where the movable part20btranslates in the optical axis orthogonal plane12cin addition to the rotation in the counterclockwise direction, the abutting portions38amay be brought into abutment with the first restricting portion22a. On the other hand, even when the rotation angle of the movable part20bbecomes the maximum in the counterclockwise direction from the state shown inFIG.6A, the abutting portions38aare not brought into abutment with the first restricting portion22a.FIG.7Bshows a state in which in a case where the rotation angle of the movable part20bbecomes the maximum in the counterclockwise direction from the state shown inFIG.6A, the movable part20bis stabilized by the plurality of restricting portions arranged to surround the optical axis12a. By arranging these components as described above, it is possible to suppress the amount of protrusion of the movable part20btoward the outside with respect to the fixed part20ain the optical axis orthogonal plane12cwhen the movable part20bis rotationally moved.

As described above, in the present embodiment, out of the movements of the movable part20bin the optical axis orthogonal plane12c, the translational movement not including the rotation about the optical axis12ais restricted only by the abutment between the abutting portions38aand the first restricting portion22a, which are arranged at locations small in distance from the optical axis12a. Further, out of the movements of the movable part20bin the optical axis orthogonal plane12c, the rotational movement about the optical axis12ais restricted by the restriction elements associated with the abutting portions201to208in a posture in which the abutting portions38aand the first restricting portion22aare not brought into abutment with each other when the rotational angle becomes the maximum. Note that the restriction elements refer to the first columnar member24a, the second restricting portion25a, the second columnar member24b, the first restricting member28, the second restricting member29, and the third columnar member24c.

Note that as described above, the elastic members, such as rubber, are provided on portions of the columnar members, the restricting portions, and the restricting members, which are brought into abutment with the movable part20b, to ease an impact and also suppress generation of collision noise. In the first blur correction unit20, the rotational movement of the movable part20bis restricted by substantially simultaneous abutment of the movable part20bwith columnar members, restricting portions, and/or restricting members, at at least three locations. This makes it possible to disperse a force acting on the columnar members, the restricting portions, or the restricting members and suppress deterioration of the elastic members.

Incidentally, in a case where the blur correction control by the first blur correction unit20is performed during actual image capturing, an operation for adjusting the position of the balls36(hereinafter referred to as the “reset operation”) is required to be performed in advance so as to prevent a situation where the balls36do not roll, causing an increase in the driving load. As the timing of the reset operation, there may be mentioned timing of immediately after the image capturing apparatus10is powered on. Further, the reset operation may be performed by a user operation. Then, next, the reset operation on the first blur correction unit20will be described in detail with reference toFIGS.8A to13B.

First, the first enclosure31d, the second enclosure31e, and the third enclosure31fwill be described. Note that the same description is given of the first enclosure31d, the second enclosure31e, and the third enclosure31f, and hence in this description, the first enclosure31d, the second enclosure31e, and the third enclosure31fare each generically referred to as the “enclosure311”.

FIG.8Ais a schematic diagram showing a relationship between the ball36and the enclosure311on the optical axis orthogonal plane12cwhen the movable part20bperforms relative movement to the fixed part20ain the optical axis orthogonal plane12c(hereinafter simply expressed as “the movable part20bmoves”). The enclosure311having a circular shape is formed in the image sensor-holding member31to prevent the ball36held between the fixed member21and the image sensor-holding member31from dropping off in any of all directions in the optical axis orthogonal plane12c. InFIG.8A, the positions of the enclosure311and the ball36before moving are indicated by broken lines. Assuming that the enclosure311as part of the movable part20bmoves to the right by a distance S as viewed inFIG.8A, the ball36rolls due to friction generated between the fixed member21and the image sensor-holding member31. At this time, the ball36rolls and moves in the same direction as the direction in which the movable part20bmoves, in other words the enclosure311moves, by a distance S/2 corresponding to half of the moving distance of the movable part20b. InFIG.8A, the positions of the enclosure311and the ball36after moving are indicated by solid lines.

FIG.8Bis a schematic diagram showing a relationship between the enclosure311and the ball36on the optical axis orthogonal plane12cin a case where the ball36is brought into abutment with the enclosure311when the movable part20bmoves. InFIG.8B, the positions of the enclosure311and the ball36before moving are indicated by broken lines. Let it be assumed that the enclosure311as part of the movable part20bmoves to the right by the distance S as viewed inFIG.8B. In a case where a distance between the left side surface of the enclosure311and the left side surface of the ball36is smaller than the distance S/2 before the movable part20bmoves, in other words the enclosure311moves, the ball36is brought into abutment with the left side surface of the enclosure311when the movable part20bis moving. As a result, the ball36cannot roll and moves by being dragged by the enclosure311in a state in contact with the enclosure311, and in this state, friction larger than in a state in which the ball36is rolling is generated. However, in a case where the movable part20bi.e. the enclosure311returns from this state to the original position (position indicated by the broken line) and then performs the same movement (movement to the position indicated by the solid line), since the ball36has moved by being dragged by the enclosure311in the first movement, the ball36is not brought into abutment with the enclosure311in second and subsequent movements.

Here, the inner diameter of the enclosure311will be described. The movement of the movable portion20bwhen the first shake correction controller15acontrols the first blur correction unit20to perform blur correction is limited within a range of a predetermined translational movement amount and a range of a predetermined rotational angle about the optical axis12a. By causing the ball36to roll such that the ball36is prevented from being brought into abutment with (the wall surface of) the enclosure311within these ranges, it is possible to reduce the friction load.

FIGS.9A and9Bare diagrams useful in explaining a relationship between a distance from the optical axis12aand the inner diameter of the enclosure311. The translational movement amount of the movable part20b, the rotational angle of rotation of the movable part20babout the optical axis12a, and the diameter of the ball36are represented by a, ϕ, and b, respectively. As shown inFIG.9A, the inner diameter of the enclosure311positioned away from the optical axis12aby a distance c is expressed by a+b+c×sin ϕ+z. Note that “z” is an amount of a mechanical margin, and has a value not smaller than 0 (zero).

FIG.9Bis a diagram showing a first area312where the ball36is to be positioned so as not to be brought into abutment with the enclosure311even when the movable part20btranslationally moves by the distance a and rotates about the optical axis12athrough the angle ϕ, for shake correction.

As described above with reference toFIG.8A, when the movable part20btranslationally moves by the distance a, the ball36rolls in the same direction by a distance a/2. Assuming that the diameter (inner diameter) of the enclosure311is represented by “D”, if the ball36is positioned within a second area313which is coaxial with the enclosure311and is surrounded by a circle having a diameter obtained by D−a, before the movable part20bmoves, even when the movable part20btranslationally moves by the distance a, the ball36is prevented from being brought into abutment with the enclosure311.

Similarly, when the movable part20brotates about the optical axis12athrough the angle ϕ, the ball36rolls in the same direction through an angle ϕ/2. Therefore, a common area between a third area313aoccupied by the second area313having rotated about the optical axis12athrough an angle+ϕ/2 and a fourth area313boccupied by the second area313having rotated about the optical axis12athrough an angle −ϕ/2 is the first area312. If the ball is positioned in the first area312, even when the movable part20brotates about the optical axis12athrough the angle ϕ, the ball36is prevented from moving out of the second area313. That is, if the ball36is positioned within the first area312, even when the movable part20btranslationally moves by the distance a and also rotates about the optical axis12athrough the angle ϕ, and the ball36is prevented from being brought into abutment with the enclosure311.

Next, a first example of the reset operation (hereinafter referred to as the “first reset operation”) will be described with reference toFIGS.10A to10C, andFIGS.11A and11B.FIGS.10A to10C, andFIGS.11A and11Bare diagrams each schematically showing an area where the ball36can be positioned with respect to the enclosure311when the movable part20bhas moved by the first reset operation.

FIG.10Ais a diagram showing a fifth area314where the ball36exists after the movable part20bhas translationally moved without rotationally moving, such that a circle having a radius e from the optical axis12aas the center is drawn. As described above, the ball36moves to a position where the ball36is not brought into abutment with the enclosure311within a range through which the movable part20bhas passed once, and hence the ball36exists within the fifth area314after moving. The diameter of the fifth area314is reduced by half of the diameter of the movement circle, i.e. “e” from the inner diameter D of the enclosure311, and hence the diameter is represented by “D−e”.

When the movable part20brotates about the optical axis12ain a counterclockwise direction (first rotational direction in which the movable part20bis rotatable about the optical axis12a) through an angle α from the state shown inFIG.10A, the ball36is accommodated within a sixth area314aindicated inFIG.10B. This is because in a case where the fifth area314is rotated about the optical axis12athrough an angle α/2 and the ball36is brought into abutment with the enclosure311at this time, the ball36is dragged by the enclosure311without rolling.

When the movable part20brotates about the optical axis12athrough the angle −α from the state shown inFIG.10B(in other words, when the movable part20brotates through the angle α in a second rotational direction opposite to the first rotational direction), the ball36is accommodated within a seventh area314bindicated inFIG.10C. Similarly, when the movable part20brotates about the optical axis12athrough the angle −α from the state shown inFIG.10C, the ball36is accommodated within an eighth area314cindicated inFIG.11A. This is because in a case where the seventh area314bis rotated about the optical axis12athrough an angle −α/2 and the ball36is brought into abutment with the enclosure311at this time, the ball36is dragged by the enclosure311without rolling. When the movable part20bis rotated about the optical axis12athrough the angle α from the state shown inFIG.11A, the ball36is accommodated within a ninth area314dindicated inFIG.11B.

Therefore, if the ninth area314dis included in the first area312, even when the movable part20btranslationally moves by the distance a and rotates about the optical axis12athrough the angle ϕ for blur correction, the ball36is prevented from being brought into abutment with the enclosure311. In other words, the first reset operation is execution of the translational movement and the rotational movement of the movable part20bas described above with reference toFIGS.10A to11B. In the first reset operation, the translational movement is performed, and hence the movement angle of the rotational movement can be reduced, and further, in the actual blur correction, it is possible to avoid abutment of the ball36against the enclosure311within the driving control range of the movable part20band maintain a state in which the driving load is small.

Next, a second example of the reset operation (hereinafter referred to as the “second reset operation”) will be described with reference toFIGS.12A to12CandFIGS.13A and13B.FIGS.12A to12C, andFIGS.13A and13Bare diagrams each schematically showing an area where the ball36can be positioned with respect to the enclosure311when the movable part20bhas moved by the second reset operation.

FIG.12Ashows a state in which the ball36exists inside the enclosure311. When the movable part20brotates about the optical axis12ain a counterclockwise direction through an angle β from the state shown inFIG.12A, the ball36is accommodated in a tenth area314eindicated inFIG.12B. This is because in a case where the area in which the ball36is accommodated, indicated inFIG.12A, is rotated about the optical axis12athrough an angle β/2, and the ball36is brought into abutment with the enclosure311at this time, the ball36is dragged by the enclosure311without rolling.

When the movable part20brotates about the optical axis12athrough an angle −β from the state shown inFIG.12B(rotates in a clockwise direction through the angle β), the ball36is accommodated in an eleventh area314findicated inFIG.12C. Similarly, when the movable part20brotates about the optical axis12athrough the angle −β from the state shown inFIG.12C, the ball36is accommodated in a twelfth area314gindicated inFIG.13A. This is because in a case where the eleventh area314fis rotated about the optical axis12athrough an angle −β/2, and the ball36is brought into abutment with the enclosure311at this time, the ball36is dragged by the enclosure311without rolling. When the movable part20brotates about the optical axis12athrough the angle β from the state shown inFIG.13A, the ball36is accommodated in a thirteenth area314hindicated inFIG.13B.

Therefore, if the thirteenth area314his included in the first area312, even when the movable part20btranslationally moves by the distance a and also rotates about the optical axis12athrough the angle for blur correction, the ball36is prevented from being brought into abutment with the enclosure311. In other words, it can be said that the second reset operation is execution of the rotational movement of the movable part20bas described above with reference toFIGS.12A to13B. However, the angle β is required to be larger than the maximum value of the rotational angle which can be controlled for blur correction. In the second reset operation, the translational movement of the movable part20bis not required, and in the actual blur correction, it is possible to avoid abutment of the ball36against the enclosure311within the driving control range of the movable part20band maintain a state in which the driving load is small.

Note that the first reset operation and the second reset operation are performed within a range within which the movable part20bis prevented from being brought into abutment with the fixed part20ain the first restricting means and the second restricting means because if the movable part20band the fixed part20aare brought into abutment with each other, collision noise is generated.

The embodiments are described above only by way of example, and it is also possible to combine the embodiments as deemed appropriate.

For example, in the above-described embodiment, the description is given of the example in which the driving device according to the present invention is applied to the image blur correction device of the image capturing apparatus. However, the driving device according to the present invention is applied not only to this, but for example, the driving device according to the present invention can be applied to an XYθ table for placing a sample to be observed on a microscope, an XYθ table for placing an object to be assembled in a variety of manufacturing devices, etc. Further, although in the above-described embodiment, as the image capturing apparatus10, the so-called mirrorless camera is described, the driving device according to the present invention can also be applied to an image blur correction device of a digital single-lens reflex camera equipped with a quick return mirror mechanism.

This application claims the benefit of Japanese Patent Application No. 2021-110972, filed Jul. 2, 2021, which is hereby incorporated by reference herein in its entirety.