JP2015055799A - Drive mechanism of optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive mechanism of an optical element having a high degree of freedom of the arrangement position of an energizing member and capable of achieving excellent use feeling and image quality by preventing looseness that rotates and moves in the direction orthogonal to the optical axis with a guide axis of an optical element holding frame as a center.SOLUTION: The drive mechanism of an optical element holds a guide shaft extending toward an optical axis direction and an optical element, and includes: an optical element holding frame movably supported in an optical axis direction along the guide shaft; an energizing member for energizing the optical element holding frame toward the optical axis direction; and drive means for moving the optical element holding frame to the optical axis direction along the guide shaft resisting against the energizing member. The guide shaft is provided with an intermediate slide member that is formed of a member different from the optical element holding frame and that receives an energizing force by the energizing member and transmits the force to the optical element holding frame.

Description

  The present invention relates to a drive mechanism for an optical element.

  In an optical device such as a camera, the optical element holding frame that holds the optical element and is movable in the optical axis direction is responsible for a part of the drive mechanism, takes backlash in the drive mechanism, or In order to stabilize the position, an urging force in the optical axis direction is often applied. The urging member for the optical element holding frame is generally constituted by a tension spring or a compression spring having an axis line in the optical axis direction. That is, one end of the tension spring or compression spring is engaged with the optical element holding frame, and the other end is engaged with another support member such as a fixed member that is not moved integrally with the optical element holding frame. The amount of movement of the holding frame is directly reflected in the amount of expansion and contraction of the spring (spring urging force).

  On the other hand, the applicant of the present invention disclosed in Patent Document 1 as an urging member for urging the optical element holding frame, instead of a tension spring or a compression spring, oscillating within an oscillating plane substantially parallel to the photographing optical axis. A torsion spring having a swinging force arm that engages with the optical element holding frame at a position away from the swing center, and biases the optical element holding frame in the optical axis direction through the swinging force arm. Proposed to use.

  However, in any urging structure such as a tension spring, a compression spring, or a torsion spring, the urging member is directly engaged with the optical element holding frame to urge it. There is a problem that there are many restrictions on the arrangement position.

  Another problem is that the optical element holding frame is movably supported by a guide shaft parallel to the photographic optical axis regardless of the biasing structure of the tension spring, compression spring, or torsion spring. The frame can be slightly rotated around the guide axis (rotation around the guide axis cannot be completely prevented).

  Specifically, in an urging structure using a tension spring or a compression spring, the direction of the urging force applied to the optical element holding frame is mainly only in the optical axis direction, and urging in a direction not parallel to the optical axis direction is performed. It is not broken (there is no resistance to force in a direction non-parallel to the optical axis direction). Therefore, when the direction of the load that is not parallel to the optical axis direction is changed due to a change in the posture of the camera or a vibration to the camera, the optical element holding frame may rotate forward and backward about the guide shaft.

  In the urging structure by the torsion spring, the direction of the urging force applied to the optical element holding frame changes according to the position of the optical element holding frame in the optical axis direction, and is not only parallel to the optical axis direction but also to the optical axis direction. May include direction. Nevertheless, as with the biasing structure using tension springs and compression springs, the optical element holding frame is centered on the guide shaft when the direction of the load is changed non-parallel to the optical axis direction due to camera posture changes or camera vibration. May rotate forward and backward. As the optical element holding frame moves along the guide axis, if the positional relationship between the swinging force arm of the torsion spring and the applying force portion of the optical element holding frame changes, the optical element holding frame is centered on the guide axis. As a result, the direction of the rotational moment (rotational force) applied to the optical element holding frame may be reversed, and as a result, the optical element holding frame may rotate forward and backward about the guide shaft.

  In addition, since there is a slight radial sliding clearance between the guide hole of the optical element holding frame and the guide shaft, the direction of the load is not parallel to the optical axis direction due to changes in camera posture or vibration to the camera. Or when the positional relationship between the swinging force arm and the force applying portion of the optical element holding frame changes in the biasing structure by the torsion spring, the optical element holding frame is perpendicular to the optical axis within the above clearance. There is a risk of rattling.

  For example, when the optical element holding frame is equipped with a focus lens, the optical element holding frame rotates forward and backward about the guide axis during observation of the viewfinder image (or recorded moving image), or the optical element holding If the frame is rattled in the direction perpendicular to the optical axis, an image skip phenomenon occurs, and the feeling of use or image quality deteriorates. In general, rotation around the guide axis of the optical element holding frame and rattling in the direction orthogonal to the optical axis are problematically occurring during observation of a viewfinder image or recording of a moving image.

JP 2009-116222 A

  The present invention has been made based on the above awareness of the problem, and has a high degree of freedom in the arrangement position of the urging member, and also has a rotation around the guide axis of the optical element holding frame and a rattling in the direction perpendicular to the optical axis. It is an object of the present invention to obtain an optical element driving mechanism capable of preventing the above and achieving an excellent usability and image quality.

  As a result of earnest research, the inventor has an intermediate slide that is formed on a guide shaft that is common to the optical element holding frame, and is formed of a member separate from the optical element holding frame, and receives the biasing force of the biasing member and transmits it to the optical element holding frame. The present invention was completed by focusing on supporting the member so as to be movable. According to this configuration, unlike the prior art, the urging member is not directly engaged with the optical element holding frame to urge it, so that the degree of freedom of the arrangement position of the urging member is increased. be able to. In addition, by devising the shape of the engaging portion (contact portion) between the optical element holding frame and the intermediate slide member, rotation around the guide axis of the optical element holding frame and rattling in the direction perpendicular to the optical axis can be prevented. Excellent usability and image quality can be achieved.

  The present invention includes a guide shaft extending in the optical axis direction, an optical element holding frame, an optical element holding frame movably supported in the optical axis direction along the guide axis, and the optical element holding frame. An optical element driving mechanism comprising: an urging member that moves and urges in an axial direction; and a driving unit that moves the optical element holding frame in the optical axis direction along the guide shaft against the urging member. The guide shaft is provided with an intermediate slide member that is formed of a member separate from the optical element holding frame and receives an urging force from the urging member and transmits the urging force to the optical element holding frame.

  The engaging portion between the optical element holding frame and the intermediate slide member generates a rotational moment in the same direction around the guide axis in the optical element holding frame over the entire movement range in the optical axis direction of both. It is preferable to make a shape.

  The vector direction of the force acting between the optical element holding frame and the intermediate slide member via the urging member is preferably non-parallel to the optical axis direction.

  It is preferable that a tangential plane of the engaging portion of the optical element holding frame and the intermediate slide member and a normal line of the tangential plane are not parallel to the optical axis direction.

  The engaging portion between the optical element holding frame and the intermediate slide member moves the optical element holding frame toward the guide axis in a certain direction within a plane orthogonal to the optical axis, thereby It is preferable to have a shape that prevents rattling in the direction perpendicular to the optical axis.

  It is preferable that the intermediate slide member has a rotation restricting protrusion that restricts the intermediate slide member from rotating about the guide shaft by engaging with a rotation restricting guide formed on the fixed member.

  The biasing member can swing in a swing plane substantially parallel to the optical axis, and has a swinging arm that engages the intermediate slide member at a position away from the swing center. The intermediate slide member can be constituted by a torsion spring that urges the intermediate slide member in the optical axis direction via an applying arm.

  Alternatively, the biasing member is configured by a tension spring or a compression spring that applies a tensile force or a compressive force in the optical axis direction of a different size to the intermediate slide member according to the position in the optical axis direction of the intermediate slide member. can do.

  Both the optical element holding frame and the engaging portion of the intermediate slide member can be composed of a plane including the optical axis and an inclined surface portion inclined with respect to the optical axis orthogonal plane.

  Or the engaging part of the said optical element holding frame and the said intermediate slide member can be comprised from the curved surface part which protrudes both in an optical axis direction.

  Alternatively, one of the engaging portions of the optical element holding frame and the intermediate slide member is composed of a plane including the optical axis and an inclined surface that is inclined with respect to the optical axis orthogonal plane, and the other protrudes in the optical axis direction. It can comprise from the curved surface part.

  The driving means drives the nut member to define the position of the optical element holding frame in the optical axis direction when the optical element holding frame is applied by the biasing force of the biasing member, and drives the nut member to A feed screw mechanism that moves the optical element holding frame in the optical axis direction by pushing the element holding frame can be provided.

  According to the present invention, the degree of freedom of the arrangement position of the urging member is high, and rotation around the guide axis of the optical element holding frame and rattling in the direction orthogonal to the optical axis are prevented, and excellent usability and image can be obtained. A drive mechanism of the optical element that can achieve quality is obtained.

It is sectional drawing in the imaging | photography state (zoom state) which shows one Embodiment of the zoom lens barrel which mounts the drive mechanism of the optical element by this invention. It is sectional drawing in the accommodation (collapsed state) which shows one Embodiment of the zoom lens barrel which mounts the drive mechanism of the optical element by this invention. It is a perspective view which shows the assembly | attachment state of a 3 group lens frame, a 3 group lens biasing spring, and an intermediate slide member. It is a perspective view which shows the decomposition | disassembly state of a 3 group lens frame, a 3 group lens urging | biasing spring, and an intermediate slide member. It is a perspective view which expands and shows a 3 group lens frame and an intermediate slide member. It is a perspective view which expands and shows the vicinity of the driven engagement part of a 3 group lens frame. It is a front perspective view which expands and shows an intermediate slide member. It is a back perspective view which expands and shows an intermediate slide member. It is a figure which expands and shows a mode that rotation centering on the 3rd group guide shaft of an intermediate slide member is controlled because the rotation control protrusion of an intermediate slide member engages with the rotation control guide of a housing. The force transmitted by the urging arm portion of the third group lens urging spring and the force applying portion of the spring projection of the intermediate slide member, and the drive engagement portion of the intermediate slide member and the driven engagement portion of the third group lens frame It is a 1st figure which shows the force transmitted by an applied force part. The force transmitted by the urging arm portion of the third group lens urging spring and the force applying portion of the spring projection of the intermediate slide member, and the drive engagement portion of the intermediate slide member and the driven engagement portion of the third group lens frame It is a 2nd figure which shows the force transmitted by an applied force part. The component of the component orthogonal to the optical axis of the force transmitted from the drive engagement portion of the intermediate slide member to the driven engagement portion of the third group lens frame, and the rotational moment (rotation) applied to the third group lens frame by this component force It is a figure which shows the direction of force. It is a figure which shows the conditions for making the load of a fixed direction act on a 3 group lens frame always. FIGS. 14A to 14D are diagrams showing variations in the shapes of the drive engagement portion of the intermediate slide member and the driven engagement portion of the third group lens frame. It is a figure corresponding to FIG. 11 which shows another embodiment using a tension spring as a biasing member which moves and biases a 3 group lens frame to an optical axis direction. It is a figure corresponding to FIG. 11 which shows another embodiment using a compression spring as an urging member which urges | biases a 3 group lens frame to an optical axis direction.

  First, an overall structure of a retractable zoom lens barrel ZL equipped with an optical element driving mechanism according to the present invention will be described mainly with reference to FIGS. The imaging optical system of the zoom lens barrel ZL includes a first lens group LG1, a shutter S, a second lens group LG2, a third lens group (optical element) LG3, a low-pass filter 25, and an imaging element in order from the object (subject) side. 26. Further, the zoom lens barrel ZL has a polarization filter 43 that can be inserted into and removed from the optical path in front of the second lens group LG2. In the following description, the optical axis direction means a direction parallel to the optical axis O of the photographing optical system, the front means front in the optical axis direction (subject side), and the rear means rear in the optical axis direction (image). Surface side). In the radial direction centered on the optical axis O, the side closer to the optical axis O is the inner diameter side, and the side farther from the optical axis O is the outer diameter side.

  The zoom lens barrel ZL has a cylindrical housing 22 as a fixing member, and the image sensor holder 21 is fixed to the rear portion of the housing 22. The low-pass filter 25 and the image sensor 26 are unitized and fixed to the rear surface portion of the image sensor holder 21.

  The third lens group (optical element) LG3 is a focus lens group in the zoom lens barrel ZL, and is held by a third group lens frame (optical element holding frame) 50. The third group lens frame 50 is supported through a guide shaft 53 (FIGS. 3, 4, and 9 to 12) so as to be linearly movable in the optical axis direction, and an AF motor 30 (drive means, feed screw mechanism). It can be moved back and forth by the driving force (FIGS. 3, 4 and 9). The support driving means for the third group lens frame 50 will be described in detail later.

  In addition to the support driving means for the third group lens frame 50, a zooming group (cam ring) block that is driven and controlled by a lens barrel drive motor (not shown) is supported inside the housing 22. The variable power group (cam ring) block includes a cam ring 11, a feeding cylinder 12, a straight guide ring 13, and a second group lens block 80.

  The cam ring 11 constitutes an external appearance cylinder of the zoom lens barrel ZL together with the feeding cylinder 12, and a guide protrusion (not shown) that is slidably fitted into a cam ring guide groove 22 a formed on the inner peripheral surface of the housing 22. Z). The cam ring 11 is rotated by receiving a driving force of a zoom gear (not shown) rotated by a lens barrel drive motor (not shown), and moves in the optical axis direction while rotating by the guide of the cam ring guide groove 22a. To do. A straight guide ring 13 is supported in the housing 22. The rectilinear guide ring 13 is guided through a rectilinear guide groove formed on the inner surface of the housing 22 so as to be able to move linearly in the optical axis direction. The rectilinear guide ring 13 can rotate relative to the cam ring 11 and moves together in the optical axis direction. Is bound to.

  The second group lens block 80 has a configuration in which the polarization filter unit 40 is fixed to the front portion of the second group lens moving ring 8, and has an outer diameter from the vicinity of the rear end of the cylindrical portion 8 a that constitutes the main body portion of the second group lens moving ring 8. By causing a straight guide key (not shown) protruding in the direction to slidably engage with a straight guide slot (not shown) which is a long hole in the optical axis direction formed in the straight guide ring 13 It is guided straight in the direction of the optical axis.

  The second lens group LG2 is held by a holding frame portion 8c formed in the cylindrical portion 8a of the second group lens moving ring 8. A polarizing filter unit 40 and a shutter unit 81 are attached to the front part of the second group lens moving ring 8. The shutter unit 81 has a shutter S that can be opened and closed inside, and the shutter S is driven to open and close by a shutter actuator 82. The polarizing filter unit 40 rotates the filter drive motor 41 in the forward and reverse directions to insert and remove the polarizing filter 43 on the optical path passing through the optical axis O, and rotate the inserted polarizing filter 43 around the optical axis O. It is possible to make it.

  A second group cam follower (not shown) is fixed on a straight guide key (not shown) of the second group lens moving ring 8. The second group cam follower is slidably engaged with a second group control cam groove CG2 formed on the inner peripheral surface of the cam ring 11. Since the second group lens moving ring 8 (second group lens block 80) is guided linearly in the optical axis direction via the straight guide ring 13, when the cam ring 11 rotates, the second group cam follower (not shown) is 2 Under the guidance of the group control cam groove CG2, the second group lens moving ring 8 (second group lens block 80) moves along a predetermined locus in the optical axis direction.

  A first lens group LG1 is held in the feeding cylinder 12. The feeding cylinder 12 moves straight in the optical axis direction by slidably engaging a linear guide key (not shown) provided on the inner surface side with a linear guide groove (not shown) formed in the linear guide ring 13. Guided. A first group cam follower 12a is provided on the outer peripheral surface near the rear end of the feeding cylinder 12, and the first group cam follower 12a slides on a first group control cam groove CG1 formed on the inner peripheral surface of the cam ring 11. Engagement possible. Since the feeding cylinder 12 is linearly guided in the optical axis direction via the linear guide ring 13, when the cam ring 11 rotates, the first group cam follower 12a receives the guidance of the first group control cam groove CG1, and the feeding cylinder 12 Moves along a predetermined locus in the optical axis direction.

  The zoom lens barrel ZL having the above structure operates as follows. In the photographing state (zoom range) shown in FIG. 1, the cam ring 11 is extended forward in the optical axis direction with respect to the housing 22, and the extension amount of the cam ring 11 is controlled by the locus of the cam ring guide groove 22a. The feeding cylinder 12 that supports the first lens group LG1 and the second group lens block 80 that supports the second lens group LG2 are guided by the cam grooves CG1 and CG2 in accordance with the rotation of the cam ring 11, respectively. Move relative to.

  When a lens barrel drive motor (not shown) is driven in the lens barrel storage direction from the photographing state shown in FIG. 1, the cam ring 11 guided by the cam ring guide groove 22a is moved rearward in the optical axis direction while rotating. The The feeding cylinder 12 and the second group lens block 80 (second group lens moving ring 8) move rearward in the optical axis direction together with the cam ring 11 with a predetermined relative movement along the locus of the cam grooves CG1 and CG2 on the cam ring 11. To do. When the lens barrel storage state shown in FIG. 2 is reached, the driving of the lens barrel drive motor (not shown) in the lens barrel storage direction is stopped. Further, the position of the third lens group frame 50 holding the third lens group LG3 is also controlled by the AF motor 30 (FIGS. 3, 4, and 9) so as to be in the retracted position shown in FIG.

  Subsequently, mainly referring to FIGS. 3 to 9, the configuration and operation of the third lens group frame (optical element holding frame) 50 holding the third lens group (optical element) LG3 and its peripheral members will be described in detail. explain. The third lens group LG3 is driven by an AF motor 30 (FIGS. 3, 4, and 9) independently of driving the first lens group LG1 and the second lens group LG2 by a lens barrel drive motor (not shown). It can be moved back and forth along the photographing optical axis O. When the photographing from the wide end to the tele end is possible, the third lens group LG3 is held by driving the AF motor 30 according to the subject distance information obtained by the distance measuring means (not shown). The third group lens frame 50 to be moved moves along the photographing optical axis O, and focusing is executed.

  As shown in FIGS. 3 to 5, the third group lens frame 50 is made of an annular member in which a lens holding portion 51 that holds the third lens group LG <b> 3 is formed at the center. A guide arm portion 52 extending in the front-rear direction is formed in a part of the third group lens frame 50 in the circumferential direction, and a pair of front and rear circular guide holes 52 a are formed at both ends in the front-rear direction of the guide arm portion 52. Is formed. A three-group guide shaft (guide shaft) 53 having a circular cross section extending in the optical axis direction is slidably inserted into the pair of guide holes 52a (FIGS. 3 and 4). A slight radial clearance exists between the guide hole 52 a of the third group lens frame 50 and the third group guide shaft 53. Both ends in the front-rear direction of the third group guide shaft 53 are supported by guide shaft support portions (not shown) formed in the housing 22.

  As shown in FIGS. 4 to 6, a nut abutting portion 54 and a driven engagement portion 55 are formed on the guide arm portion 52 of the third group lens frame 50. The nut abutting portion 54 is formed so as to protrude from the side of the guide arm portion 52 in the direction perpendicular to the optical axis. The driven engagement portion 55 includes a curved surface portion (semi-cylindrical portion) that protrudes rearward from the rear end portion of the guide arm portion 52 in the optical axis direction.

  As shown in FIGS. 3 to 5, a bifurcated guide portion 56 is formed in the third group lens frame 50 so as to be different from the guide arm portion 52 (guide hole 52 a) in the circumferential direction. A rotation regulating guide shaft 57 having a circular cross section extending in the optical axis direction is slidably inserted into the bifurcated guide portion 56. Here, since there is a circumferential clearance between the bifurcated guide portion 56 and the rotation restricting guide shaft 57, the third group lens frame 50 can be slightly rotated around the third group guide shaft 53. Yes (rotation around the third group guide shaft 53 cannot be completely prevented).

  As shown in FIGS. 3 to 5 and 7 to 9, the third group guide shaft 53 is positioned immediately after the third group lens frame 50, and is an intermediate slide member that is a separate member from the third group lens frame 50. 60 is slidably provided. As shown in an enlarged view in FIGS. 7 and 8, the intermediate slide member 60 is formed of a block body in which an insertion hole 61 through which the third group guide shaft 53 is slidably inserted is formed at the center.

  The intermediate slide member 60 has an L-shaped projecting portion 62 that extends in the direction perpendicular to the optical axis from the side of the intermediate slide member 60 and is bent rearward in the optical axis direction. On the short side (optical axis orthogonal wall) of the L-shaped projecting portion 62, there is formed a spring hooking projection 63 composed of a curved surface portion (semi-cylindrical portion) projecting rearward in the optical axis direction.

  The intermediate slide member 60 has a drive engagement portion 64 including a plane including the optical axis and an inclined surface portion inclined with respect to the plane orthogonal to the optical axis in front of the intermediate slide member 60. The drive engagement portion 64 is provided at a position where it engages with the driven engagement portion 55 of the third group lens frame 50.

  The intermediate slide member 60 has a rotation restricting protrusion 65 that protrudes from the side of the intermediate slide member 60 in a different position from the L-shaped protrusion 62. The rotation restricting protrusion 65 is engaged with a rotation restricting guide 22b formed on the housing 22 (FIGS. 3 and 9). As a result, the rotation of the intermediate slide member 60 around the third group guide shaft 53 is restricted to a certain extent, but as shown in FIG. 9, there is a circumferential clearance between the rotation restricting projection 65 and the rotation restricting guide 22b. Therefore, the intermediate slide member 60 can be slightly rotated around the third group guide shaft 53 (the rotation around the third group guide shaft 53 cannot be completely prevented).

  As shown in FIGS. 3 and 4, the zoom lens barrel ZL is a third group lens biasing spring 70 as a biasing member that applies a biasing force toward the front of the photographing optical axis O to the third group lens frame 50. It has. The third group lens urging spring 70 is formed of a torsion spring member, and the coil portion 71 is supported by a spring support protrusion 22 c provided on the housing 22 with its axis line directed in a direction orthogonal to the third group guide shaft 53.

  The third group lens urging spring 70 includes a short linear support arm portion 72 (FIG. 10) and a long linear urging arm portion (oscillating force arm) 73 from the coil portion 71 toward the outer diameter direction. It is extended. Of these, the support arm portion 72 is hung (engaged) on a spring hooking protrusion (not shown) formed on the housing 22 in the vicinity of the spring support protrusion 22c. On the other hand, the urging arm portion 73 has its tip portion hooked (engaged) with the spring hooking protrusion 63 of the intermediate slide member 60.

  The urging arm 73 can swing about a swing center axis 71X substantially coincident with the axis of the coil portion 71 (ie, a fulcrum) (that is, swing within a swing plane substantially parallel to the photographing optical axis O). In a free state that is a swingable force-applying portion that is not hung on the spring-hanging projection 63, it faces upward in FIG. Then, from this free state, the urging arm 73 is rotated about half a clockwise direction in FIG. 3, and the tip end portion (swinging force arm) of the urging arm 73 is rearward in the optical axis direction of the spring projection 63. The amount of bending (twisting) of the third group lens urging spring 70 is increased by applying to the surface of the lens, and the urging arm portion 73 presses the spring hooking protrusion 63 forward in the optical axis direction due to the force in the direction of deflecting. Acting as a load. The load transmitted to the intermediate slide member 60 via the spring protrusion 63 is further passed from the intermediate slide member 60 to the third group lens frame 50 via the engagement portion between the drive engagement portion 64 and the driven engagement portion 55. Is transmitted to. In other words, it is in an applied force state in which an urging force forward in the optical axis direction is applied to the third group lens frame 50 via the urging arm portion 73 of the third group lens urging spring 70.

  In the third group lens frame 50 thus provided with the urging force forward from the third group lens urging spring 70 in the optical axis direction, the nut abutting portion 54 is a nut of the AF nut (drive means, nut member) 31. By abutting against the contact portion 32, the forward movement is restricted (FIG. 4). That is, the third group lens frame 50 is held in a state in which the nut abutting portion 54 is in contact with the nut abutting portion 32 of the AF nut 31 by the urging force of the third group lens urging spring 70. The front and rear positions in the optical axis direction are determined depending on the AF nut 31 (the third group lens frame 50 and the AF nut 31 move integrally in the optical axis direction).

  A mechanism for moving the AF nut 31 back and forth in the optical axis direction will be described. The AF motor 30 has a feed screw (drive means, feed screw mechanism) 33 directly connected to the rotating shaft protruding forward in the optical axis direction, and the AF nut 31 is screwed with the feed screw 33. A hole (not shown, hidden in the AF motor 30 in FIG. 4) is formed. The AF nut 31 is slidably supported by an AF nut guide shaft (drive means) 34 extending in the optical axis direction parallel to the third group guide shaft 53 and the feed screw 33. With the above configuration, when the AF motor 30 is driven to rotate in the forward and reverse directions, the AF nut 31 moves forward and backward in the optical axis direction by the feed screw 33. As a result, the position of the third group lens frame 50 in the optical axis direction is controlled according to the driving direction and driving amount of the AF motor 30. For example, when the AF nut 31 is moved forward by the AF motor 30, the third group lens frame 50 is moved forward by the urging force of the third group lens urging spring 70 by the amount of movement of the AF nut 31. On the other hand, when the AF nut 31 is moved backward from the forward movement position, the nut abutting portion 32 of the AF nut 31 pushes the nut abutting portion 54 of the third group lens frame 50, and the third group lens frame 50 is in the third group. The lens biasing spring 70 is moved backward against the biasing force of the lens biasing spring 70.

  Now, mainly referring to FIGS. 10 to 13, when the third group lens frame 50 and the intermediate slide member 60 move in the entire movement region in the optical axis direction between the front movement end and the rear movement end, the third group The force F transmitted by the biasing portion of the biasing arm portion 73 of the lens biasing spring 70 and the spring hooking protrusion 63 of the intermediate slide member 60, the drive engagement portion 64 of the intermediate slide member 60, and the third group lens frame 50. Note the force F ′ transmitted by the force applying portion of the driven engagement portion 55.

[Force F transmitted by the force applying portion of the urging arm portion 73 of the third group lens urging spring 70 and the spring protrusion 63 of the intermediate slide member 60]
In the zoom lens barrel ZL of the present embodiment, the biasing arm portion 73 of the third group lens biasing spring 70 and the biasing portion of the spring projection 63 of the intermediate slide member 60 according to the position of the intermediate slide member 60 in the optical axis direction. The magnitude and direction (vector component) of the force F transmitted in the above fluctuate.

  The spring force F transmitted from the distal end portion of the urging arm portion 73 of the third group lens urging spring 70 to the spring hooking protrusion 63 of the intermediate slide member 60 is the distal end of the urging arm portion 73 of the third group lens urging spring 70. It works in the direction orthogonal to the extending direction of the urging arm 73 from the force applying portion of the spring-hanging projection 63 of the intermediate slide member 60. The spring force F is divided into a component force that works along the axial direction of the third group guide shaft 53 and a component force that works perpendicular to the axial direction of the third group guide shaft 53.

  The former component force is essentially a force necessary to urge the intermediate slide member 60 in the optical axis direction, and does not have any adverse effect on the operation of the zoom lens barrel (optical element drive mechanism) ZL. .

  On the other hand, the latter component force is a force for pushing the intermediate slide member 60 in the direction orthogonal to the optical axis, and a rotational moment (rotational force) for rotating the intermediate slide member 60 about the third group guide shaft 53. Give rise to This component force is directed leftward in FIG. 10 (rightward in FIG. 12) until the intermediate slide member 60 moves from the rearward movement end to the intermediate position. In FIG. The direction of the rotational moment for rotating the intermediate slide member 60 around is the counterclockwise direction. On the other hand, this component force is directed in the right direction in FIG. 10 (left direction in FIG. 12) until the intermediate slide member 60 moves beyond the intermediate position to the forward movement end. The direction of the rotational moment for rotating the intermediate slide member 60 around the group guide shaft 53 is the clockwise direction. Thus, as the intermediate slide member 60 moves along the third group guide shaft 53 in the optical axis direction, the tip of the urging arm 73 of the third group lens urging spring 70 and the intermediate slide member 60 are moved. The direction of the rotational moment (component force) that causes the rotational force about the third group guide shaft 53 to act on the intermediate slide member 60 is changed clockwise in FIG. Reverse in direction and counterclockwise.

  However, the rotation of the intermediate slide member 60 around the third group guide shaft 53 is restricted by engaging the rotation restricting protrusion 65 with the rotation restricting guide 22b formed on the housing 22 (FIG. 3, FIG. 3). FIG. 9). For this reason, the reversal of the rotational moment due to the change in the positional relationship between the distal end portion of the urging arm 73 of the third group lens urging spring 70 and the force applying portion of the spring hook 63 of the intermediate slide member 60 is the third group lens. It is not transmitted to the frame 50.

[Force F ′ transmitted by the force applying portion of the driving engagement portion 64 of the intermediate slide member 60 and the driven engagement portion 55 of the third group lens frame 50]
The force F ′ transmitted by the driving engagement portion 64 of the intermediate slide member 60 and the applied force portion of the driven engagement portion 55 of the third group lens frame 50 is the optical axis direction of the third group lens frame 50 (intermediate slide member 60). Over the entire movement region, the magnitude and direction (vector component) of the force F transmitted by the biasing arm portion 73 of the third group lens biasing spring 70 and the biasing portion of the spring projection 63 of the intermediate slide member 60. First, a rotational moment (rotational force) in the same direction around the third group guide shaft 53 is generated in the third group lens frame 50.

  That is, the drive engagement portion 64 of the intermediate slide member 60 includes a plane including the optical axis and an inclined surface portion inclined with respect to the plane orthogonal to the optical axis, and the driven engagement portion 55 of the third group lens frame 50 includes the optical axis. It is composed of a curved surface portion (semi-cylindrical portion) that protrudes rearward in the direction, and the shape of the force-applying portion of both the engaging portions 64 and 55 is within the entire movement range in the optical axis direction of the third group lens frame 50 (intermediate slide member 60). The third group lens frame 50 is set so as to generate a rotational moment in the same direction around the third group guide shaft 53.

  More specifically, between the third group lens frame 50 and the intermediate slide member 60 via the third group lens biasing spring 70 over the entire movement region in the optical axis direction of the third group lens frame 50 (intermediate slide member 60). The vector direction of the force acting on the optical axis is not parallel to the optical axis direction. Further, the engagement of the drive engagement portion 64 of the intermediate slide member 60 and the driven engagement portion 55 of the third group lens frame 50 over the entire movement range of the third group lens frame 50 (intermediate slide member 60) in the optical axis direction. The tangent plane of the joint portion (the force applying portion) and the normal line of this tangential plane are not parallel to the optical axis direction.

  The force F ′ transmitted from the drive engagement portion 64 of the intermediate slide member 60 to the driven engagement portion 55 of the third group lens frame 50 is covered by the drive engagement portion 64 of the intermediate slide member 60 and the third group lens frame 50. It works in the direction orthogonal to the inclined surface of the drive engagement portion 64 from the force applying portion of the drive engagement portion 55. This force F ′ is divided into a component force F′y that works along the axial direction of the third group guide shaft 53 and a component force F′x that works perpendicular to the axial direction of the third group guide shaft 53.

  The component force F′y is essentially a force required to push the third group lens frame 50 in the optical axis direction, and does not have any adverse effect on the operation of the zoom lens barrel (optical element driving mechanism) ZL. .

  The component force F′x is a force for pushing the third group lens frame 50 in the direction orthogonal to the optical axis, and a rotational moment (rotational force) for rotating the third group lens frame 50 around the third group guide shaft 53. Cause it to occur. The component force F′x is directed leftward in FIGS. 11 and 12 over the entire movement region of the third group lens frame 50 in the optical axis direction. In FIG. The direction of the rotational moment for rotating the third group lens frame 50 around the center is the clockwise direction. For this reason, the rotation restricting guide shaft 57 is always applied to one end portion in the circumferential direction of the bifurcated guide portion 56 of the third group lens frame 50. As a result, even when the positional relationship between the front end portion of the urging arm 73 of the third group lens urging spring 70 and the force applying portion of the spring projection 63 of the intermediate slide member 60 changes, the third group lens frame 50 ( The third group lens frame 50 is prevented from rotating forward and backward about the third group guide shaft 53 over the entire movement range in the optical axis direction of the intermediate slide member 60), and excellent usability and image quality are obtained. Can be achieved.

  The engaging portion 64 of the intermediate slide member 60 and the engaging portion of the driven engagement portion 55 of the third group lens frame 50 are arranged in a plane orthogonal to the optical axis with respect to the third group guide shaft 53. By moving them in a certain direction, the third lens group frame 50 is shaped to prevent backlash in the direction perpendicular to the optical axis. Thus, although there is a slight radial sliding clearance between the guide hole 52a of the third group lens frame 50 and the third group guide shaft 53, the third group lens frame 50 within this clearance range. Can be prevented from rattling in the direction perpendicular to the optical axis, and excellent usability and image quality can be achieved.

  The above-described rotation of the third lens group frame 50 around the guide shaft 53 and rattling in the direction orthogonal to the optical axis is caused by a change in the direction of the load that is not parallel to the optical axis direction due to a change in the posture of the camera or a vibration to the camera. Can happen as well. However, the rotation and optical axis about the guide shaft 53 of the third group lens frame 50 are caused by the action of the drive engagement portion 64 of the intermediate slide member 60 and the engagement portion of the driven engagement portion 55 of the third group lens frame 50. The backlash in the orthogonal direction can be prevented, and excellent usability and image quality can be achieved.

  Here, referring to FIG. 13, a condition for constantly applying a load (rotational moment) in a certain direction to the third group lens frame 50 (the driving engagement portion 64 of the intermediate slide member 60 and the cover of the third group lens frame 50). The condition of the shape of the drive engagement portion 55 will be described. In the drawing, the angle θ indicates an angle formed by the plane orthogonal to the optical axis and the tangent plane of the drive engagement portion 64 of the intermediate slide member 60 and the driven engagement portion 55 of the third group lens frame 50. Here, the range in which the angle θ should be satisfied (the lower limit value of the range that the angle θ can take) is obtained.

  There is a slight circumferential clearance between the rotation restricting protrusion 65 of the intermediate slide member 60 and the rotation restricting guide 22 b of the housing 22, and a slight clearance between the insertion hole 61 of the intermediate slide member 60 and the third group guide shaft 53. Since there is a clear clearance, a frictional force is generated in the drive engagement portion 64 of the intermediate slide member 60 and the driven engagement portion 55 of the third group lens frame 50 within the range. Therefore, the direction of the force in the direction orthogonal to the optical axis acting on the third group lens frame 50 is temporarily changed depending on the magnitude of friction and the direction of action, so that the rotation around the guide shaft 53 of the third group lens frame 50 and Since there is a possibility of rattling in the direction perpendicular to the optical axis, the condition of the angle θ for preventing such a situation from occurring is obtained.

  When the intermediate slide member 60 receives an urging force F from the third group lens urging spring 70, a vertical drag R acts on the intermediate slide member 60 from the third group lens frame 50. Further, since the intermediate slide member 60 is about to rotate or move, a friction force of μR (μ is a friction coefficient) works from the third group lens frame 50 to the intermediate slide member 60 at the maximum. As the reaction force, the normal drag R ′ and the frictional force μR ′ act on the third group lens frame 50 from the intermediate slide member 60. Therefore, it is necessary that the total X-direction force (the left-right direction force in FIG. 13) of the vertical drag R ′ and the frictional force μR ′ acting on the third group lens frame 50 always acts in the same direction.

The force F′x in the direction perpendicular to the optical axis acting on the third group lens frame 50 can be obtained by Expression (1) with the leftward direction in FIG. 13 being positive.
(1) F′x = R′Sinθ−μR′Cosθ
Therefore, in order to make the force F′x acting on the third group lens frame 50 in the direction orthogonal to the optical axis always constant, it is necessary to satisfy the expression (2).
(2) F′x> 0
The following formulas (3), (4), (5), and (6) are developed based on the formulas (1) and (2), and if the formula (6) is satisfied, the third group lens frame 50 is satisfied. The force F′x acting in the direction perpendicular to the optical axis can always be made constant.
(3) F′x = R′Sinθ−μR′Cosθ> 0
(4) R′Sinθ> μR′Cosθ
(5) Sinθ> μCosθ
(6) Tanθ> μ
For example, when the friction coefficient μ = 0.25, Tan θ = 0.25, that is, θ = 14.05 °, and the lower limit of the possible range of θ is 14.05 °.

In the above embodiment, as shown in FIG. 14A, the drive engagement portion 64 of the intermediate slide member 60 is composed of a plane including the optical axis and an inclined surface portion inclined with respect to the plane orthogonal to the optical axis. The case where the driven engagement portion 55 of the lens frame 50 is formed of a curved portion protruding rearward in the optical axis direction has been described as an example.
However, various changes in design are possible for the shapes of the drive engagement portion 64 of the intermediate slide member 60 and the driven engagement portion 55 of the third group lens frame 50.
FIGS. 14B to 14D show another embodiment of the shapes of the drive engagement portion 64 of the intermediate slide member 60 and the driven engagement portion 55 of the third group lens frame 50. FIG.
In FIG. 14B, the drive engagement portion 64 of the intermediate slide member 60 is a curved portion protruding forward in the optical axis direction, and the driven engagement portion 55 of the third group lens frame 50 includes the optical axis. It consists of an inclined surface part inclined with respect to the plane and the optical axis orthogonal plane.
In FIG. 14C, both the drive engagement portion 64 of the intermediate slide member 60 and the driven engagement portion 55 of the third group lens frame 50 are inclined with respect to the plane including the optical axis and the optical axis orthogonal plane. It consists of a face part.
In FIG. 14D, the drive engagement portion 64 of the intermediate slide member 60 is a curved surface portion protruding forward in the optical axis direction, and the driven engagement portion 55 of the third group lens frame 50 is in the optical axis direction. It consists of a curved part protruding backward.

In the above embodiment, the case where the third group lens biasing spring 70 made of a torsion spring is used as the biasing member that moves and biases the third group lens frame 50 in the optical axis direction has been described as an example.
However, as shown in FIG. 15, the biasing member that moves and biases the third lens group frame 50 in the optical axis direction is different from the intermediate slide member 60 according to the position of the intermediate slide member 60 in the optical axis direction. A mode in which a tension spring 90 that provides a tensile force is also possible. In this aspect, one end of the tension spring 90 is hooked (engaged) with the spring hooking protrusion 63 of the intermediate slide member 60, and the other end of the tension spring 90 is fixed to a fixing member (not shown).
Alternatively, as illustrated in FIG. 16, the biasing member that moves and biases the third lens group frame 50 in the optical axis direction is different from the intermediate slide member 60 depending on the position of the intermediate slide member 60 in the optical axis direction. A mode in which a compression spring 95 that gives the compression force is also possible. In this aspect, one end of the compression spring 90 is fixed to the rear end of the intermediate slide member 60 so as to hide the third group guide shaft 53, and the other end of the compression spring 90 is fixed to a fixing member (not shown). ing. Further, the L-shaped protrusion 62 and the spring hooking protrusion 63 of the intermediate slide member 60 are omitted.

  14A to 14D and FIGS. 15 and 16, the rotational moment for rotating the third group lens frame 50 around the third group guide shaft 53 is always the same. The rotation restriction guide shaft 57 is always applied to one end portion in the circumferential direction of the bifurcated guide portion 56 of the third lens group frame 50. Further, the third group lens frame 50 is offset in a certain direction within the plane orthogonal to the optical axis with respect to the third group guide shaft 53. Thereby, rotation around the third group guide shaft 53 of the third group lens frame 50 and rattling in the direction perpendicular to the optical axis can be prevented, and excellent usability and image quality can be achieved.

  As described above, the zoom lens barrel (optical element driving mechanism) ZL of the present embodiment is formed of a member separate from the third group guide shaft (guide shaft) 53 and the third group lens frame (optical element holding frame) 50, An intermediate slide member 60 that receives the urging force of the third group lens urging spring (urging member) 70 and transmits the urging force to the third group lens frame (optical element holding frame) 50 is provided. According to this configuration, unlike the conventional product, the urging member is not directly engaged with the optical element holding frame to urge it, so that the degree of freedom of the arrangement position of the urging member is increased. Can do. In addition, by devising the shape of the engaging portion (contact portion) between the optical element holding frame and the intermediate slide member, rotation around the guide axis of the optical element holding frame and rattling in the direction perpendicular to the optical axis can be prevented. Excellent usability and image quality can be achieved.

  In the above embodiment, the third group lens biasing spring 70 has been described by exemplifying a mode in which the third group lens biasing spring 70 applies a biasing force toward the front of the photographing optical axis O to the third group lens frame 50. It is also possible to adopt a mode in which 70 applies an urging force toward the rear of the photographing optical axis O to the third group lens frame 50.

  In the above embodiment, the circular guide hole 52a formed in the third group lens frame (optical element holding frame) 50 is slidably fitted to the circular third group guide shaft (guide shaft) 53. Even in the relationship of the hole axis having a non-circular cross section, slight forward / reverse rotation of the third group lens frame 50 around the axis may occur due to the clearance between the hole axes. That is, the present invention can also be applied to a lens barrel that moves the optical element holding frame back and forth in the direction of the optical axis in relation to the non-circular hole axis.

  In the above embodiments, the optical element moved forward and backward in the optical axis direction is the focusing lens group. However, in the present invention, the optical elements other than the focusing lens group (for example, moved forward and backward in the optical axis direction during zooming). The present invention can also be applied as a drive mechanism for a variable magnification lens group.

ZL zoom lens barrel (optical element drive mechanism)
8 Group 2 lens moving ring 8a Tubular portion 8c Holding frame portion 11 Cam ring 12 Feeding tube 12a Group 1 cam follower 13 Straight guide ring 21 Image sensor holder 22 Housing (fixing member)
22a Cam ring guide groove 22b Rotation restriction guide 22c Spring support protrusion 25 Low pass filter 26 Image sensor 30 AF motor (drive means, feed screw mechanism)
31 AF nut (drive means, nut member)
32 Nut contact part (drive means)
33 Lead screw (drive means, lead screw mechanism)
34 AF nut guide shaft (drive means)
40 Polarizing filter unit 41 Filter driving motor 43 Polarizing filter 50 Third group lens frame (optical element holding frame)
51 Lens holding portion 52 Guide arm portion 52a Guide hole 53 Third group guide shaft (guide shaft)
54 Nut abutting portion 55 Driven engagement portion 56 Bifurcated guide portion 57 Rotation restriction guide shaft 60 Intermediate slide member 61 Insertion hole 62 L-shaped projection 63 Spring engagement protrusion 64 Drive engagement portion 65 Rotation restriction protrusion 70 Third lens group Biasing spring (biasing member, torsion spring)
71X Oscillating center shaft 71 Coil part 72 Support arm part 73 Energizing arm part (oscillating force arm)
80 Second lens block 81 Shutter unit 82 Shutter actuator 90 Tension spring (biasing member)
95 Compression spring (biasing member)
CG1 First group control cam groove CG2 Second group control cam groove LG1 First lens group LG2 Second lens group LG3 Third lens group (optical element)
S Shutter

Claims (12)

A guide shaft extending in the optical axis direction;
An optical element holding frame that holds the optical element and is movably supported in the optical axis direction along the guide axis;
An urging member for urging and moving the optical element holding frame in the optical axis direction;
Driving means for moving the optical element holding frame in the optical axis direction along the guide shaft against the biasing member;
In the drive mechanism of the optical element comprising:
An optical element drive characterized in that the guide shaft is provided with an intermediate slide member that is made of a member different from the optical element holding frame and receives the urging force of the urging member and transmits it to the optical element holding frame. mechanism. The drive mechanism for an optical element according to claim 1.
The engaging portion between the optical element holding frame and the intermediate slide member generates a rotational moment in the same direction around the guide axis in the optical element holding frame over the entire movement range in the optical axis direction of both. A drive mechanism for an optical element having a shape. The drive mechanism for an optical element according to claim 1 or 2,
An optical element driving mechanism in which a vector direction of a force acting between the optical element holding frame and the intermediate slide member via the urging member is not parallel to the optical axis direction. In the drive mechanism of the optical element according to any one of claims 1 to 3,
The optical element drive mechanism in which the tangential plane of the engaging portion of the optical element holding frame and the intermediate slide member and the normal line of the tangential plane are not parallel to the optical axis direction. In the drive mechanism of the optical element according to any one of claims 1 to 4,
The engaging portion between the optical element holding frame and the intermediate slide member moves the optical element holding frame toward the guide axis in a certain direction within a plane orthogonal to the optical axis, thereby A drive mechanism for an optical element having a shape that prevents rattling in the direction perpendicular to the optical axis. In the drive mechanism of the optical element according to any one of claims 1 to 5,
The intermediate slide member engages with a rotation restricting guide formed on the fixed member, thereby driving an optical element having a rotation restricting protrusion that restricts the intermediate slide member from rotating about the guide shaft. mechanism. In the drive mechanism of the optical element according to any one of claims 1 to 6,
The biasing member can swing in a swing plane substantially parallel to the optical axis, and has a swinging arm that engages the intermediate slide member at a position away from the swing center. A drive mechanism for an optical element comprising a torsion spring that biases the intermediate slide member in the optical axis direction via a force arm. In the drive mechanism of the optical element according to any one of claims 1 to 6,
The biasing member is an optical element composed of a tension spring or a compression spring that applies a tensile force or a compressive force in the optical axis direction of a different size to the intermediate slide member according to the position in the optical axis direction of the intermediate slide member. Drive mechanism. The drive mechanism for an optical element according to any one of claims 1 to 8,
The engaging portion of the optical element holding frame and the intermediate slide member is an optical element driving mechanism comprising both a plane including the optical axis and an inclined surface portion inclined with respect to the optical axis orthogonal plane. The drive mechanism for an optical element according to any one of claims 1 to 8,
The optical element drive mechanism of the optical element holding frame and the intermediate slide member are formed of a curved surface part projecting in the optical axis direction. The drive mechanism for an optical element according to any one of claims 1 to 8,
One of the engaging portions of the optical element holding frame and the intermediate slide member includes a plane including the optical axis and an inclined surface inclined with respect to the optical axis orthogonal plane, and the other is a curved surface protruding in the optical axis direction. An optical element drive mechanism comprising: The drive mechanism for an optical element according to any one of claims 1 to 11,
The driving means drives the nut member to define the position of the optical element holding frame in the optical axis direction when the optical element holding frame is applied by the biasing force of the biasing member, and drives the nut member to An optical element driving mechanism comprising: a feed screw mechanism that moves the optical element holding frame in the optical axis direction by pushing the element holding frame.

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