JP2009134249A - Mechanism for controlling position of optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mechanism for controlling a position of an optical element, capable of removing a backlash in an advance-retraction guide mechanism of a holding member of the optical element with a simple and space-saved constitution. <P>SOLUTION: This mechanism for controlling the position of the optical element, has the holding member for holding the optical element, an advance-retraction guide member for movably supporting the holding member in the optical axis direction passing through the optical element, and an energizing means rockable in the optical axis direction in a force-applied state of engaging with the holding member and simultaneously applying energizing force in the moving direction guided by the advance-retraction guide member to the holding member and energizing force in the orthogonal direction to the moving direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a position control mechanism for an optical element that is moved in an optical axis direction in an optical apparatus.

In an optical device such as a camera, as a forward / backward guide structure for moving a holding member of an optical element such as a lens group in the optical axis direction, a guide shaft (shaft) whose longitudinal direction is parallel to the optical axis relative to the guide hole Known are those that are slidably inserted, and those in which guide protrusions are slidably engaged with guide grooves that are oriented in the longitudinal direction parallel to the optical axis.
JP 2000-206391 A

  In this type of advancing / retreating guide structure, a predetermined clearance for enabling relative sliding is provided at sliding portions such as between the guide hole and the guide shaft and between the guide groove and the guide projection. Then, backlash removal is performed in order to prevent the occurrence of looseness and noise due to this clearance and to perform stable position control. An object of the present invention is to provide an optical element position control mechanism capable of performing backlash removal in the advance / retreat guide mechanism of the holding member of the optical element with a simple and space-saving configuration.

  The optical element position control mechanism of the present invention includes a holding member that holds the optical element, an advance / retreat guide member that movably supports the holding member in the optical axis direction passing through the optical element, and an applied force that engages the holding member. It is possible to swing in a plane parallel to the optical axis, and simultaneously apply an urging force in the moving direction guided by the advance / retreat guide member to the holding member and an urging force in a direction perpendicular to the moving direction. It is characterized by having a force means.

  As the optical element position control mechanism of the present invention, a coil part supported by a support member different from the holding member with the axis line oriented in a direction orthogonal to the optical axis passing through the optical element, and an outer diameter direction from the coil part A first arm portion extending toward the holding member and a second arm portion extending from the coil portion toward the outer diameter direction and engaged with the support member. In the free state where the biasing means is constituted by a spring member that changes the amount of bending in the rotational direction around the coil portion according to the movement, and the first arm portion of the spring member is not engaged with the holding member, It is possible to adopt a mode that is located outside the rocking surface defined by the rocking and is elastically deformed in a direction approaching the rocking surface when it is in an applied state to the holding member.

  Alternatively, as an urging means, one end is pivotally supported by a support member different from the holding member and the other end engages with the holding member, and is urged in either the forward or reverse rotation direction with respect to the swing center. In a free state in which the lever member is not engaged with the holding member, the lever member is located outside the rocking surface defined by the rocking motion. You may comprise so that it may be elastically deformed in the approaching direction.

  In the case of a forward / backward guide structure in which a guide shaft whose axis is directed in the optical axis direction is slidably inserted into a guide hole formed in the holding member, the urging means is located near the guide hole with respect to the holding member. It is preferable to press the inner wall of the guide hole against the guide shaft and press against the guide shaft. In this case, the holding member is provided with a protrusion that protrudes from the contact portion in the vicinity of the guide hole and is positioned on the extension of the swinging direction of the biasing member and receives the biasing force in the moving direction of the holding member. Is preferred.

  In the optical element position control mechanism of the present invention, it is more effective to further include a pressing unit that presses the urging unit in a direction applied to the holding member in a direction perpendicular to the moving direction of the holding member.

  Specifically, a fixed wall member is provided on at least one of the outer side and the inner side of the urging unit, and the urging unit abuts against the fixed wall member and presses in a direction orthogonal to the moving direction of the holding member. Configured to be. The fixed wall member may be either an outer wall member located outside the urging means or an inner wall means located inside the urging means. In the case of the outer wall member, the urging means in the direction approaching the optical axis. In the case of the inner wall member, the urging means is pressed in a direction away from the optical axis.

  It is effective to provide the fixed wall member with a protruding pressing portion that comes into contact with the biasing means. Alternatively, the biasing means may have a bent shape that is convex toward the fixed wall member, and the bent portion may be in contact with the fixed wall member.

  Further, an inner cylindrical member positioned outside the holding member and an outer wall member facing the outer surface of the inner cylindrical member are provided, and the urging means is held between the inner cylindrical member and the outer wall member. It is good to comprise so that it may contact | abut either of them and may be pressed in the direction orthogonal to the moving direction of a holding member.

  According to the present invention described above, the urging means for moving and urging the holding member in the direction along the optical axis passing through the optical element also performs urging in the direction orthogonal to the moving direction. Backlash removal at the advancing / retreating guide portion can be performed with a simple and space-saving configuration. Further, by providing means for pressing the biasing means in a state of being applied to the holding member in a direction orthogonal to the moving direction of the holding member, a higher effect can be obtained with respect to the backlash removal of the advance / retreat guide portion.

  First, the overall structure of the zoom lens barrel 1 to which the optical element position control mechanism of the present invention is applied will be described mainly with reference to FIGS. 1 and 2 show a cross section of the zoom lens barrel 1. FIG. 1 is a storage state in which shooting is not performed, the upper half section of FIG. 2 is the wide end of the zoom shooting area, and the lower half section of FIG. Each edge is shown. 3 and 4 are perspective views corresponding to the storage state of FIG. 1, and FIGS. 5 and 6 are perspective views corresponding to the photographing state of FIG.

  The zoom lens barrel 1 includes, in order from the object (subject) side, a first lens group LG1, a second lens group LG2, a diaphragm shutter S, a third lens group LG3, a low-pass filter LPF, and a CCD (imaging device) 24. In addition, a three-group imaging optical system is provided. This optical system is a zoom optical system with a variable focal length, and performs zooming by advancing and retracting the first lens group LG1 and the second lens group LG2 along a photographing optical axis O of the optical system along a predetermined locus. Further, focusing is performed by moving the third lens group LG3 along the photographing optical axis O.

  The zoom lens barrel 1 includes a fixed barrel (support member) 22 that movably supports an optical system from the first lens group LG1 to the third lens group LG3, and a barrel rear surface plate 23 that is fixed to the rear portion thereof. It has. The CCD 24 is held in the opening formed at the center of the lens barrel rear plate 23 via the CCD holding frame 62, and the low-pass filter LPF is held by the filter holding frame 21 provided at the front of the CCD holding frame 62. ing. Sealing (dust-proof) packing 61 is sandwiched between the low-pass filter LPF and the CCD 24. The CCD holding frame 62 is supported so as to be capable of adjusting the inclination with respect to the lens barrel rear plate 23.

  The fixed barrel 22 includes a cylindrical cylindrical housing portion 22a that surrounds the photographing optical axis O, a zoom motor support portion 22b that supports the zoom motor 32, an AF motor support portion 22c that supports the AF motor 30, and the AF And a front wall portion 22d positioned in front of the motor support portion 22c. The cylindrical housing portion 22a holds the optical elements such as the lens groups described above and constitutes a substantial outer shape portion of the zoom lens barrel 1. The zoom motor support portion 22b, the AF motor support portion 22c, and the front wall portion 22d are positioned outside the cylindrical housing portion 22a in the radial direction with the photographing optical axis O as the center. As shown in FIGS. 3 to 7, the AF motor support portion 22 c is provided at substantially the same position in the optical axis direction as the rear end portion of the cylindrical housing portion 22 a, and the rear surface portion is blocked by the lens barrel rear surface plate 23. It is. The front wall portion 22d is formed at a facing position that is spaced forward in the optical axis direction with respect to the AF motor support portion 22c.

  The third group lens frame (holding member) 51 that holds the third lens group LG3 extends from the central lens holding portion 51a with a pair of guide arm portions 51b and 51c in a substantially symmetrical direction across the photographing optical axis O. I am letting. Of these, a pair of front and rear guide holes 51d is formed at the tip of one guide arm 51b, and a three-group guide fixed between the fixed barrel 22 and the barrel rear plate 23 with respect to the guide hole 51d. A shaft (advance / retreat guide member) 52 is slidably inserted. As shown in FIGS. 6 and 10, the third group guide shaft 52 is disposed outside the cylindrical housing portion 22a of the fixed barrel 22, and the front end portion thereof is supported by the front wall portion 22d. The rear end portion of the third group guide shaft 52 passes below the AF motor support portion 22c and is fitted into a support hole (not shown) formed in the lens barrel rear surface plate 23. In order to receive the guide of the third group guide shaft 52, the guide arm portion 51b of the third group lens frame 51 has a tip portion projecting outward from the cylindrical housing portion 22a of the fixed barrel 22, An opening 22e (FIG. 7) that allows the guide arm portion 51b to protrude is formed in the cylindrical housing portion 22a. A rotation restricting projection 51e provided at the tip of the other guide arm portion 51c of the third group lens frame 51 is slidably engaged with a rectilinear guide groove 22f formed on the inner peripheral surface of the fixed barrel 22. is doing. The axis of the third group guide shaft 52 and the longitudinal direction of the rectilinear guide groove 22f are parallel to the photographing optical axis O, respectively. The guide hole 51d and the rotation restricting projection 51e are formed by the third group guide shaft 52 and the rectilinear guide groove 22f. The third group lens frame 51 is guided in a straight line so as to be movable in a direction parallel to the photographing optical axis O. The third group lens frame 51 can be moved back and forth along the photographing optical axis O by the AF motor 30. A driving mechanism of the third group lens frame 51 will be described later.

  A reduction gear train that transmits the driving force of the zoom motor 32 to the zoom gear 31 (FIGS. 6 and 7) is provided inside the zoom motor support 22b of the fixed barrel 22. An annular gear 11 a that meshes with the zoom gear 31 is provided at the rear end of the cam ring 11 that is supported inside the cylindrical housing portion 22 a of the fixed barrel 22, and the cam ring 11 is connected to the zoom motor 32 via the zoom gear 31. It is rotationally driven by. A guide projection 11b projecting from the annular gear 11a of the cam ring 11 in the outer diameter direction is provided, and the guide projection 11b is formed with respect to a cam ring control groove 22g formed on the inner peripheral surface of the cylindrical housing portion 22a of the fixed barrel 22. Are slidably engaged. The cam ring control groove 22g includes a lead groove portion having a predetermined inclination with respect to the photographing optical axis O and a circumferential groove portion including only a circumferential component centered on the photographing optical axis O. When the rotational force is applied by the zoom motor 32 between the storage (collapsed) state of FIG. 1 and the wide end of the upper half section of FIG. 2, the cam ring 11 has the guide protrusion 11b formed by the lead groove portion of the cam ring control groove 22g. It moves in the direction of the optical axis while being guided and rotated. On the other hand, when the photographing state is between the wide end and the tele end, the guide protrusion 11b is positioned in the circumferential groove portion of the cam ring control groove 22g, and the cam ring 11 moves in the optical axis direction according to the driving of the zoom motor 30. Rotated in place without

  On the inner side of the cylindrical housing portion 22a of the fixed barrel 22, the first feeding cylinder 13 and the rectilinear guide ring 10 are supported so as to sandwich the cam ring 11. The first feed cylinder 13 is guided in a straight line in the optical axis direction by the engagement relationship of the straight guide groove 13h with a straight guide groove 22h formed on the inner peripheral surface of the cylindrical housing portion 22a. Is guided linearly in the optical axis direction by the engagement relationship of the rectilinear guide protrusion 10a with the rectilinear guide groove 22i formed on the inner peripheral surface of the housing 22a. The first feeding cylinder 13 and the linear guide ring 10 are coupled to the cam ring 11 so as to be capable of relative rotation and move together in the optical axis direction.

  The rectilinear guide ring 10 guides the second group lens moving frame 8 rectilinearly in the optical axis direction by a rectilinear guide key 10b (FIG. 2) located inside the cam ring 11. A second lens group LG <b> 2 is supported inside the second group lens moving frame 8 via a second group lens holding frame portion 6. Further, a rectilinear guide groove 13b parallel to the photographing optical axis O is formed on the inner peripheral surface of the first feed cylinder 13, and the rectilinear guide protrusion 12a of the second feed cylinder 12 is slidable in the rectilinear guide groove 13b. The second feeding cylinder 12 is also guided in a straight line in the optical axis direction. The first lens group LG <b> 1 is supported inside the second feeding cylinder 12 via the first group lens holding frame portion 4.

  A second group cam follower 8 a provided on the outer peripheral surface of the second group lens moving frame 8 is engaged with the second group control cam groove 11 c formed on the inner peripheral surface of the cam ring 11. Since the second group lens moving frame 8 is linearly guided in the optical axis direction via the straight guide ring 10, when the cam ring 17 rotates, the second group lens moving frame 8, i.e., the first group moving frame 8 is moved according to the shape of the second group control cam groove 11c. The two lens group LG2 moves along a predetermined locus in the optical axis direction.

  The second feeding cylinder 12 has a first group cam follower 12b protruding in the inner diameter direction, and the first group cam follower 12b is slidably fitted in a first group control cam groove 11d formed on the outer peripheral surface of the cam ring 11. is doing. Since the second feeding cylinder 12 is guided linearly in the direction of the optical axis via the first feeding cylinder 13, when the cam ring 11 rotates, the second feeding cylinder 12, that is, the first feeding cylinder 12 according to the shape of the first group control cam groove 11d. The lens group LG1 moves along a predetermined locus in the optical axis direction.

  The second group lens moving frame 8 and the second feeding cylinder 12 are urged in a direction away from each other by an intergroup urging spring 27, between the second group control cam groove 11c and the second group cam follower 8a, and 1 The fitting accuracy between the group cam follower 12b and the first group control cam groove 11d is increased.

  A shutter block 15 having a shutter S is supported inside the second group lens moving frame 8. Guide protrusions 8b and 5a that make a pair in the direction parallel to the photographing optical axis O approach each other on the second group lens moving frame 8 and the rear regulating member 5 provided at the rear of the second group lens moving frame 8. The shutter block 15 is supported so as to be slidable in the optical axis direction with respect to the guide protrusions 8b and 5a.

  A decorative plate 16 is fixed to the front end portion of the second feeding cylinder 12, and a barrier member 17 that opens and closes a photographing opening 16 a in front of the first lens group LG <b> 1 on the decorative plate 16 is provided.

  The zoom lens barrel 1 having the above structure operates as follows. In the lens barrel storage state shown in FIG. 1, the length of the optical system in the photographic optical axis direction (distance from the object side surface of the first lens group LG1 to the imaging surface of the CCD 24) is shorter than in the imaging state of FIG. ing. When the main switch provided in the camera is turned on in the lens barrel storage state, the zoom motor 32 is driven in the lens barrel feeding direction. The zoom gear 31 is rotationally driven by the zoom motor 32, the guide protrusion 11 b is guided to the lead groove portion of the cam ring control groove 22 g of the fixed barrel 22, and the cam ring 11 is rotated and fed forward in the optical axis direction. The rectilinear guide ring 10 and the first feed cylinder 13 move forward together with the cam ring 11. When the cam ring 11 rotates, on the inner side, the second group lens moving frame 8 guided linearly through the straight guide ring 10 is predetermined in the optical axis direction due to the relationship between the second group cam follower 8a and the second group control cam groove 11c. It is moved by the trajectory. Further, when the cam ring 11 rotates, the second feeding cylinder 12 guided linearly through the first feeding cylinder 13 on the outside of the cam ring 11 is related to the first group cam follower 12b and the first group control cam groove 11d. Is moved along a predetermined locus in the optical axis direction.

  That is, the first lens group LG1 and the second lens group LG2 are fed out from the lens barrel retracted state by the former moving amount of the cam ring 11 with respect to the fixed barrel 22 and the second feeding amount with respect to the cam ring 11, respectively. It is determined as a sum of the cam feed amount of the cylinder 12 and the latter is a sum of the amount of forward movement of the cam ring 11 with respect to the fixed barrel 22 and the cam feed amount of the second group lens moving frame 8 with respect to the cam ring 11. Determined. Zooming is performed by moving the first lens group LG1 and the second lens group LG2 on the photographing optical axis O while changing the air interval between them. When the lens barrel is extended from the housed state of FIG. 1, first, the wide end extended state shown in the upper half section of FIG. 2 is obtained, and when the zoom motor 32 is further driven in the lens barrel extending direction, the lower half section of FIG. As shown in FIG. In the zoom region between the tele end and the wide end, the cam ring 11 performs only the above-mentioned fixed position rotation by the guide protrusion 11b being positioned in the circumferential groove portion of the cam ring control groove 22g, and in the optical axis direction. Do not advance or retreat. When the main switch is turned off, the zoom motor 32 is driven in the lens barrel storage direction, and the zoom lens barrel 1 performs a storage operation opposite to the above-described feeding operation, and enters the storage state of FIG.

  In the photographing state of FIG. 2 in the zoom lens barrel 1, the shutter S is positioned behind the second lens group LG2, while in the retracted state of FIG. The relative position in the optical axis direction is moved forward, so that the second lens group LG2 and the shutter S partially overlap.

  The third lens group LG3 can be moved back and forth along the photographing optical axis O by the AF motor 30, independently of the driving of the first and second lens groups LG1 and LG2 by the zoom motor 32 described above. Then, when the photographing from the wide end to the tele end is possible, the third group lens frame that supports the third lens group LG3 by driving the AF motor 30 according to the subject distance information obtained by the distance measuring means. 51 is moved along the photographing optical axis O to perform focusing.

  Next, details of the position control mechanism of the third group lens frame 51 will be described. As described above, the fixed barrel 22 is formed with the AF motor support portion 22c outside the cylindrical housing portion 22a, and the front wall portion 22d is formed facing the front of the AF motor support portion 22c. . The AF motor 30 is fixed to the front surface side of the AF motor support portion 22c by a fixing screw 33, and a pinion 30a provided on the rotation shaft of the AF motor 30 projects to the rear surface side of the AF motor support portion 22c. A reduction gear 34 meshing with the pinion 30a and a feed screw gear 35 meshing with the reduction gear 34 are pivotally supported on the rear surface side of the AF motor support portion 22c. It is transmitted to the feed screw 36 that rotates integrally with the feed screw gear 35 via the reduction gear train. The front end portion of the feed screw 36 is pivotally supported by a shaft hole formed in the front wall portion 22d of the fixed barrel 22, and the rear end portion is pivotally supported by a shaft hole formed in the lens barrel rear surface plate 23. In this state, the feed screw 36 is rotatable by a rotation center substantially parallel to the photographing optical axis O.

  A nut abutting portion 51f having a through hole through which the feed screw 36 is inserted is formed at the distal end portion of the guide arm portion 51b of the third group lens frame 51, and is positioned in front of the nut abutting portion 51f. An AF nut 37 having a screw hole that is screwed into the feed screw 36 is provided. The AF nut 37 engages a rotation-preventing concave portion 37 a (FIG. 7) with a rotation-preventing projection 51 g (FIG. 8) of the third group lens frame 51, and a rotation-preventing convex portion 37 b around the fixed barrel 22. The rotation is restricted by engaging with a recess (not shown) for stopping, and by moving the feed screw 36 forward and backward, it moves forward and backward in parallel with the photographic optical axis O without rotating with the feed screw 36. Is done. Further, an L-shaped spring-hanging projection (projection) 51 h is projected from the tip of the guide arm portion 51 b of the third group lens frame 51 so as to be positioned between the pair of front and rear guide holes 51 d.

  A third group lens biasing spring (spring member) 38 is provided as a biasing unit that applies a biasing force in the moving direction along the photographing optical axis O to the third group lens frame 51. The third group lens biasing spring 38 is a torsion spring, and its coil portion 38 a is supported by a spring support protrusion 22 j provided on the fixed barrel 22. The spring support protrusion 22j is a cylindrical protrusion formed on the outside of the cylindrical housing portion 22a with the axis line directed to the side substantially orthogonal to the photographing optical axis O, and is formed at the center of the spring support protrusion 22j. By fixing the spring retaining screw 39 to the threaded hole, the coil portion 38a of the third group lens biasing spring 38 is held against the cylindrical outer surface of the spring support projection 22j. The axis of the coil portion 38a in the holding state substantially coincides with the axis of the spring support protrusion 22j.

  The third group lens biasing spring 38 includes a short support arm portion (second arm portion) 38b and a long biasing arm portion (biasing means, first arm portion) from the coil portion 38a toward the outer diameter direction. 38c is extended. Of these, the support arm portion 38b is hung on a spring hooking protrusion 22k (FIG. 12) formed on the fixed lens barrel 22 in the vicinity of the spring support protrusion 22j. On the other hand, the urging arm portion 38 c is hung on the spring hooking protrusion 51 h of the third group lens frame 51. The urging arm portion 38c can oscillate around an oscillation center axis 38x substantially coincident with the axis of the coil portion 38a (ie, a fulcrum) (that is, oscillate in an oscillation plane substantially parallel to the photographing optical axis O). In a free state that is not swingable on the spring hooking protrusion 51h, it is directed in the direction indicated by "38c (F)" in FIG. Then, from this free state, the urging arm portion 38c is rotated about half a counterclockwise in FIG. 12, and the vicinity of the tip end portion of the urging arm portion 38c is applied to the rear surface in the optical axis direction of the spring projection 51h. As a result, the amount of bending (twisting) of the third group lens urging spring 38 is increased, and the force in the sag-removing direction acts as a load for the urging arm portion 38c to press the spring hooking protrusion 51h forward in the optical axis direction. To do. That is, it is in an applied state in which an urging force forward in the optical axis direction is applied to the third group lens frame 51 via the urging arm portion 38c.

  In this way, the third group lens frame 51 applied with the urging force forward in the optical axis direction from the third group lens urging spring 38 is moved forward by the nut abutting portion 51f against the AF nut 37. Movement is restricted. That is, as shown in FIGS. 8, 9 and 12, the third group lens frame 51 is held in a state where the nut abutting portion 51f is in contact with the AF nut 37 by the urging force of the third group lens urging spring 38. The front and rear positions of the third group lens frame 51 in the optical axis direction are determined depending on the AF nut 37. As described above, the AF nut 37 is moved forward and backward in the direction parallel to the photographing optical axis O by the feed screw 36 by rotating the pinion 30a of the AF motor 30 in the forward and reverse directions. The position of the frame 51 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 37 is moved forward by the AF motor 30, the third group lens frame 51 is moved forward by the urging force of the third group lens urging spring 38 by the amount of movement of the AF nut 37. On the other hand, when the AF nut 37 is moved backward from the forward movement position, the AF nut 37 pushes the nut abutting portion 51f, and the third group lens frame 51 resists the biasing force of the third group lens biasing spring 38. Moved backwards.

  The fixed barrel 22 is provided with an origin position detection sensor 40 that detects a rearward movement end of the third group lens frame 51 in the optical axis direction by the AF motor 30. The origin position detection sensor 40 is composed of a transmissive photo interrupter, and the state in which the sensor passage plate 51i of the third group lens frame 51 is located between the bifurcated light projecting portion and the light receiving portion is behind the third group lens frame 51. Detected as moving end. The AF motor 30 is a stepping motor, and the amount of movement of the third lens group LG3 during focusing is calculated as the number of driving steps of the AF motor 30 with the rearward movement end as the origin position.

  A solid line in FIG. 12 shows the rear moving end of the third group lens frame 51 in the movable range controlled by the AF motor 30, and a two-dot chain line in FIG. 12 shows in the movable range. This is the front moving end of the third group lens frame 51. FIG. 14A shows the variation in the load of the third group lens urging spring 38 according to the change in the position of the third group lens frame 51 in the optical axis direction. When the third group lens frame 51 is located at the rear moving end and when the third group lens frame 51 is located at the front moving end, the swing angle of the urging arm portion 38c from the free state (the amount of deflection of the third group lens urging spring 38). The magnitudes are represented by θmin and θmax, respectively. The loads of the third group lens urging springs corresponding to the swing angles θmin and θmax of the urging arm portions 38c are Fmin and Fmax. As can be seen from FIG. 12, the displacement θv between the minimum swing angle θmin and the maximum swing angle θmax in the applied state in the third group lens biasing spring 38 is the minimum swing from the free state to the applied state. It is much smaller than the angle θmin. Therefore, the fluctuation from the minimum load Fmin to the maximum load Fmax of the third group lens biasing spring 38 in the movable range of the third group lens frame 51 is suppressed to a small value.

  FIG. 13 shows a comparative example in which a tension spring 38 ′ that expands and contracts in a direction parallel to the photographing optical axis O is provided in place of the third group lens biasing spring 38. One end of the tension spring 38 ′ is hooked on the spring hooking protrusion 51 h ′ of the third group lens frame 51 ′, and the other end is hooked on the spring hooking protrusion 22 j ′ of the fixed barrel 22 ′. The third group lens frame 51 'is movable back and forth along the third group guide shaft 52' in parallel with the photographic optical axis O, and behind the third group lens frame 51 'within a movable range controlled by the AF motor 30'. The moving end is indicated by a solid line, and the forward moving end is indicated by a two-dot chain line. In addition, the lengths of the tension springs 38 'with reference to the engaging positions with the spring engaging projections 22j' on the fixed barrel 22 'side at the respective front and rear moving ends of the third group lens frame 51' are indicated by Lmin and Lmax. ing. Since the spring-hanging projection 22j 'at the fixed position is located at the front, the tension spring 38' is the longest (Lmax) at the rearward movement end of the third lens group frame 51 '. Lf is the length of the tension spring 38 'in the free state.

  FIG. 14B shows the fluctuation of the load due to the tension spring 38 'in the comparative example of FIG. Fmin ′ and Fmax ′ in the figure are spring loads when the length of the tension spring 38 ′ is Lmin and Lmax, respectively. As can be seen from FIG. 13, the tension spring 38 ′ is in an applied state more than the displacement amount Lv 1 from the length LF in the free state to the minimum length Lmin in the applied state to the third group lens frame 51 ′. The displacement amount Lv2 between the minimum length Lmin and the maximum length Lmax is significantly larger. Since the magnitude of the load of the tension spring 38 'varies in proportion to the change in its length, the tension spring 38' has a difference between the load Fmin 'at the minimum length Lmin and the load Fmax' at the maximum length Lmax. It becomes very big. A powerful AF motor 30 'corresponding to the maximum load Fmax' is required.

  In order to suppress the load fluctuation, that is, to make the change in length between the longest time and the shortest time relatively small, it is conceivable to extend the length of the tension spring 38 'in the free state. However, if the tension spring 38 'is made longer, a larger installation space is required, which is against the demand for downsizing the lens barrel. The comparative example of FIG. 13 has the same structure as that of the embodiment of FIG. 12 except for the tension spring 38 ′. If the total length of the tension spring 38 ′ is increased, the front end of the lens barrel in the stored state will be described. The spring hooking protrusion 22j ′ must be positioned ahead (right side in FIG. 13) of the part position (substantially equal to the front end position of the fixed barrel 22 ′). That is, if an attempt is made to arrange the elongated tension spring 38 ', the lens barrel storage length becomes large. In that sense, the tension spring 38 ′ in the comparative example of FIG. 13 has already been given the maximum possible length in terms of the structure of the lens barrel, and FIG. 14 ( It is difficult to keep the load fluctuation smaller than shown in b), and it is impossible to satisfy the demands for reducing the size of the lens barrel and suppressing the load fluctuation at the same time.

  Further, if the movable range of the third group lens frame 51 'is reduced (if the rearward movement end is set in front of the solid line position in FIG. 13), the maximum load is reduced without increasing the free length of the tension spring 38'. However, it is not practical because the amount of lens movement is limited and the required optical performance may not be obtained.

  Although the tension spring 38 'is used in the comparative example of FIG. 13, there is a similar problem even if this is replaced with a compression spring. That is, regardless of whether the spring is a tension spring or a compression spring, a spring member that expands and contracts between the third group lens frame 51 'and the fixed member (fixed barrel 22') in the advancing and retracting direction of the third group lens frame 51 '. In the urging structure that is directly connected with the, it is difficult to achieve both compactness and suppression of load fluctuation.

  On the other hand, in the configuration of the present embodiment in which the third group lens biasing spring 38 is used as the biasing means of the third group lens frame 51, as can be seen from the comparison between FIG. 14A and FIG. Although it is an urging means provided in an equivalent arrangement space, its load fluctuation is much smaller than that of the comparative example, and the maximum load of the spring is also smaller than that of the comparative example. As a result, the energy required for driving the third group lens frame 51 is averaged at a low level, and the power consumption in the AF motor 30 can be suppressed. In other words, the power-saving AF motor 30 can be used. Further, since the load fluctuation according to the movement of the third group lens frame 51 is small, it can be driven smoothly over the entire moving range, and abnormal noise from the driving mechanism that transmits the driving force from the AF motor 30 is also generated. Hard to occur.

  As described above, in the third group lens biasing spring 38, the swing displacement amount (θv) of the biasing arm portion 38c in the acting section (between the front and rear moving ends of the third group lens frame 51) is as follows. This is smaller than the swing displacement amount (θmin) of the urging arm portion 38c from the free state to the applied (engaged) state to the third group lens frame 51, and has a relationship of θv / θmin <1. Therefore, the load fluctuation in the applied force state is suppressed to a small level. In the embodiment shown in FIG. 12, the magnitude of θmin is set to about half a rotation, but by increasing the value of θmin, which is the denominator (θmax increases as θmin increases, θv is constant), The swing displacement amount θv of the urging arm portion 38c in the operating section in the state can be made relatively small, and the difference between the maximum load and the minimum load of the third group lens urging spring 38 can be further reduced. Satisfying θv / θmin <1 is effective in suppressing load fluctuations, but more preferably, a remarkable effect can be obtained by satisfying θv / θmin <0.5. As a specific method for increasing the value of θmin, the urging arm portion 38c may be twisted one or more turns from the free state to engage with the spring hooking protrusion 51h. The size of the third group lens biasing spring 38 made of a torsion spring does not change substantially even if the amount of deflection in the rotational direction around the coil portion 38a is increased. Unlike the case of extending the free state length of the spring, there is no need to increase its installation space. If conditions such as the thickness of the steel wire constituting the spring are the same, if the amount of deflection of the third group lens biasing spring 38 from the free state to the applied state is increased, the load also increases on average. Therefore, the amount of deflection is set within a range where the maximum load is not excessive.

  As a factor that the load fluctuation is suppressed to be small in the third group lens biasing spring 38, the biasing arm portion 38c from the coil portion 38a that is the pivot point of the swing to the point of application (operation point) to the third group lens frame 51 is shown. The length of is also related. As the distance from the swing center of the biasing arm portion 38 to the applied force point, that is, the rotation radius of swing near the tip of the third group lens biasing spring 38 increases, the bias per unit movement amount of the third group lens frame 51 increases. The displacement angle (θv) of the arm portion 38c becomes small, and the fluctuation of the spring load can be suppressed. As shown in FIG. 10, when a plane P including the photographing optical axis O and parallel to the oscillation center axis 38x of the third group lens urging spring 38 (in this embodiment, the plane P is a horizontal plane) is assumed. The spring hooking protrusion 51h, which is the engagement position of the urging arm portion 38c with the third group lens frame 51, is located in a region above the plane P. On the other hand, the spring support projection 22j that supports the coil portion 38a that is the swing center of the third group lens urging spring 38 is provided in a region below the plane P. Therefore, the urging arm portion 38c of the third group lens urging spring 38 extends in the vertical direction (top and bottom) of the zoom lens barrel 1 across the plane P. Since the third group lens urging spring 38 is provided at a radially outer position than the cam ring 11 which is a rotating member inside the lens barrel, the first lens group LG1 and the second lens group driven by the cam ring 11 are provided. The biasing arm portion 38c can have such a length without interfering with the movable member relating to LG2.

  Also in the front projection shape of the zoom lens barrel 1, the position control mechanism of the third group lens frame 51 including the third group lens biasing spring 38 is arranged with high space efficiency. As shown in FIG. 10, elements such as a third group guide shaft 52 constituting a guide mechanism of the third group lens frame 51, an AF nut 37, an AF motor 30 and a feed screw 36 constituting a drive mechanism of the third group lens frame 51. Is disposed in a triangular space along the outer peripheral surface of the cylindrical housing portion 22a of the fixed barrel 22 above the plane P. The coil portion 38 a of the third group lens urging spring 38 is supported by a lower triangular space that is substantially plane-symmetric with respect to the upper triangular space and the plane P. In many cases, the front projection shape of an optical device such as a camera on which the zoom lens barrel 1 is mounted is based on a square, but according to this arrangement relationship, the position control mechanism of the third group lens frame 51 is a square. It can be efficiently accommodated in a dead space between the housing portion of the optical device and the outer peripheral surface of the cylindrical housing portion 22a. As can be seen from FIG. 10, the urging arm portion 38c of the third group lens urging spring 38 is substantially the outer peripheral surface of the cylindrical housing portion 22a from the lower triangular space toward the upper triangular space. Is extended in the vicinity of the cylindrical housing portion 22a. Therefore, even if the third group lens urging spring 38 is provided outside the cylindrical housing portion 22a, the horizontal width of the zoom lens barrel 1 is hardly affected.

  As described above, the urging structure of the third group lens frame 51 by the third group lens urging spring 38 of the present embodiment contributes to reducing the size of the zoom lens barrel 1, particularly to reducing the storage length, while maintaining the AF motor. It is possible to reduce power consumption by reducing 30 loads.

  A second embodiment of the present invention will be described with reference to FIGS. 15 and 16. In the first embodiment shown in FIGS. 1 to 12 and 14, the movement of the third group lens frame 51 is controlled by the feed screw 36 and the AF nut 37, but in the second embodiment, the lens group LG is controlled. As a driving mechanism for the lens frame (holding member) 151 that holds the lead, a lead cam shaft 136 is used instead of the feed screw. The lens frame 151 has a guide shaft (advancing / retracting guide member) 152 slidably inserted into a guide hole formed in the cylindrical portion 151a, and a substantially symmetrical position with the cylindrical portion 151a and the photographing optical axis O interposed therebetween. A cylindrical portion that is guided in a straight line in a direction parallel to the photographic optical axis O and is guided by the guide shaft 152 by slidably engaging the detent shaft 153 with the detent groove 151d formed in A guide pin 151b protrudes from 151a. The guide pin 151 b is engaged with a lead groove 136 a formed on the peripheral surface of the lead cam shaft 136. The lead groove 136a has a pair of opposed guide surfaces that are inclined with respect to the photographing optical axis O, and allows the guide pin 151b to slide between the pair of opposed guide surfaces and the guide pin 151b. A predetermined clearance is provided. A gear 135 is provided at one end of the lead cam shaft 136, and when the rotational force is applied by the motor 130 via the gear 135, the lead cam shaft 136 is rotationally driven by a rotation center parallel to the photographing optical axis O. Then, the guide pin 151b is slidably guided by the guide surface of the lead groove 136a, and the lens frame 151 is moved in the optical axis direction.

  A lens frame urging spring (biasing means) 138 formed of a torsion spring directs the axis of the coil portion 138a in a direction orthogonal to the photographing optical axis O, and the coil portion 138a is placed on the outer peripheral surface of the cylindrical spring support protrusion 122j. It is supported. The position of the spring support protrusion 122j is fixed. Then, one support arm portion (second arm portion) 138b is engaged with the fixing protrusion 122k, and the other biasing arm portion (first arm portion) 138c is spring-loaded protrusion (projection portion) of the lens frame 151. 151c is engaged. In this engaged state, the urging arm portion 138c of the lens frame urging spring 138 oscillates about the oscillating central axis 138x that substantially coincides with the axis of the coil portion 138a supported by the spring support protrusion 122j. The lens frame 151 is urged forward in the optical axis direction (leftward in FIG. 15). By this urging force, the guide pin 151b is pressed against one guide surface in the optical axis direction among a pair of guide surfaces opposed to the lead groove 136a, and the backlash between the lead groove 136a and the guide pin 151b. Is removed. Since the spring hooking protrusion 151c is provided at substantially the center in the longitudinal direction of the cylindrical portion 151a, the cylindrical portion 151a is inclined with respect to the guide shaft 152 when receiving the load of the lens frame biasing spring 138. Such a moment is hardly generated, and the smooth movement of the lens frame 151 in the optical axis direction is guaranteed.

  According to the lens frame biasing spring 138, when the lens frame 151 is moved back and forth in the optical axis direction via the motor 130 and the lead cam shaft 136, the applied force is the same as that of the third group lens biasing spring 38 of the previous embodiment. The fluctuation of the spring load in the state can be reduced, and the load on the motor 130 can be reduced. Further, when changing from the free state to the applied state, even if the rotation amount of the urging arm 138c is changed, the installation space for the lens frame urging spring 138 itself does not increase, and the space efficiency is also excellent. This is the same as the group lens biasing spring 38. As can be seen from the second embodiment, the application of the urging means to the optical element holding member in the present invention is not limited to the one directly involved in driving the advance / retreat member as in the first embodiment, The lens frame biasing spring 138 may be used for backlash removal. The driving mechanism for the holding member such as the lens frame 151 is not limited to the groove and the projection such as the lead groove 136 and the guide pin 151b in the present embodiment, but has a structure such as a face cam (end face cam). May be. In short, the present invention can be widely applied to any drive mechanism that requires backlash removal between the guide surface and the follower that is in sliding contact with the guide surface.

  In the first and second embodiments, the urging means for the third group lens frame 51 and the lens frame 151 are a third group lens urging spring 38 and a lens frame urging spring 138, each of which is a single torsion spring. . However, if the urging means satisfies such a requirement that the urging force is applied to the holding member via a swinging force applying portion that oscillates in the direction of the optical axis passing through the optical element held by the holding member, such a single unit is sufficient. It is not limited to the torsion spring. Next, with reference to FIG. 17 and the following, third to fifth embodiments in which the mode of the urging means is different will be described. Each of the following embodiments is common to the first embodiment except for the biasing means and the configuration related thereto, and the elements common to the first embodiment are denoted by the same reference numerals and the same member names.

  In the third embodiment shown in FIGS. 17 to 19, the biasing means for the third group lens frame 51 is constituted by a swing lever (biasing means, lever member) 70 and a torsion spring 238. One end of the swing lever 70 is rotatably supported with respect to the swing support protrusion 22m provided on the fixed barrel 22, and the swing center substantially coincides with the axis of the swing support protrusion 22m. It can swing in a plane parallel to the photographing optical axis O with the axis 70x as the center (fulcrum). The other end portion of the swing lever 70 is engaged with a lever engagement protrusion 51j provided on the third group lens frame 51. A coil portion 238a of a torsion spring 238 is further fitted and supported on the outer peripheral surface of the swing support protrusion 22m. The torsion spring 238 engages the support arm portion 238b extending from the coil portion 238a in the outer diameter direction with the fixed protrusion 22n of the fixed barrel 22, and the biasing arm portion 238c near the shaft support portion of the swing lever 70. The rocking lever 70 is urged to rotate clockwise in FIG. The urging force with respect to the swing lever 70 acts to press the third group lens frame 51 forward in the optical axis direction via the lever engaging projection 51j.

  The swing lever 70 itself does not have elasticity in the swing direction. However, when the biasing force is applied by the torsion spring 238, the swing arm 238c of the torsion spring 238, the swing lever 70, However, in practice, it functions as a swinging force applying portion similar to the urging arm portions 38c and 138c of the urging springs 38 and 138 in the first and second embodiments. Therefore, like the urging means in the previous embodiment, the load on the AF motor 30 can be reduced by suppressing the load fluctuation in the applied state with respect to the third group lens frame 51 while being able to be arranged in a space-saving manner. Unlike this embodiment, the coil portion 138a of the torsion spring 238 can be supported by a support portion different from the swing support protrusion 22m of the swing lever 70.

  In the fourth embodiment shown in FIG. 20, the torsion spring 238 is replaced with a tension spring 338 as an urging member for the swing lever 70 employed in the third embodiment. The swing lever 70 is substantially opposite to the main arm 70a in addition to the main arm 70a extending from the shaft support portion by the swing support protrusion 22m in the engaging direction with the lever engaging protrusion 51j of the third group lens frame 51. It has a spring arm 70b extending in the direction. The tension spring 338 has one end engaged with the spring arm 70b and the other end engaged with a spring protrusion 22p formed on the fixed barrel 22, and its axial direction is substantially parallel to the photographing optical axis O. It is arranged to be. In the swing lever 70, the length D1 of the main arm 70a from the center of the swing support protrusion 22m to the engaging portion E1 with the lever engagement protrusion 51j and the tension spring 338 from the center of the swing support protrusion 22m. The length D2 of the spring hanging arm 70b up to the joint E2 is in a relationship of D1> D2. Depending on the ratio of the lengths of the main arm 70a and the spring hook arm 70b (lever ratio), the amount of movement (fluctuation) of the engaging portion E1 on the main arm 70a side per unit movement amount of the third group lens frame 51 in the optical axis direction. The latter is smaller in the amount of movement in the rotational direction around the moving support protrusion 22m) and the amount of movement (same) of the engaging portion E2 on the spring hook arm 70b side. As a result, as can be seen from the comparison between FIG. 13 and FIG. 20, the displacement Lv3 between the minimum length Lmin and the maximum length Lmax of the tension spring 338 in the applied state with respect to the third group lens frame 51 is reduced, and the bias is applied. The variation of the load can be suppressed as compared with the case where a single tension spring is used as the means, and the load on the AF motor 30 can be reduced by reducing the maximum load.

The fifth embodiment in FIG. 21 is obtained by replacing the tension spring 338 of the fourth embodiment with a tension spring 438 having a different tension direction. The swing lever 70 protrudes the spring hook arm 70c from the shaft support portion by the swing support protrusion 22m with a rotational direction phase substantially orthogonal to the main arm 70a. The tension spring 438 has one end engaged with the spring arm 70 c and the other end engaged with a spring protrusion 22 q formed on the fixed barrel 22, and its axial direction is substantially perpendicular to the photographing optical axis O. It arrange | positions so that the lens-barrel may face the up-down direction. In the swing lever 70, the length D1 of the main arm 70a from the center of the swing support protrusion 22m to the engagement portion E1 with the lever engagement protrusion 51j and the tension spring 438 from the center of the swing support protrusion 22m. The length D3 of the spring hook arm 70c up to the joint E3 is in a relationship of D1> D3. Therefore, when the third group lens frame 51 moves back and forth in the optical axis direction, the spring hooking arm 70c is larger than the moving amount of the engaging portion E1 on the main arm 70a side (moving amount in the rotational direction around the swinging support protrusion 22m). The amount of movement (same) of the side engaging portion E3 is smaller. As a result, the amount of displacement Lv4 between the minimum length Lmin and the maximum length Lmax of the tension spring 438 in the applied state with respect to the third group lens frame 51 becomes smaller, than when a single tension spring is used as the biasing means. The fluctuation of the load can be suppressed, and the load on the AF motor 30 can be reduced by reducing the maximum load.

  In the fourth and fifth embodiments, the ratio of the length (D1) of the main arm 70a in the swing lever 70 to the lengths (D2, D3) of the spring hanging arms 70b and 70c is D2 <D1 / 2, Alternatively, it is preferable that D3 <D1 / 2 is satisfied.

  As can be seen from the fourth and fifth embodiments, the load is applied not only to the torsion spring but also to the type of spring that expands and contracts in the axial direction by interposing the swing lever 70 as the biasing means of the third group lens frame 51. Fluctuations can be suppressed. From this point of view, the same effect can be obtained even if the urging means is constituted by a combination of a compression spring and a swing lever instead of the tension springs 338 and 438 as in the fourth and fifth embodiments.

  In each of the above embodiments, the urging means for moving and urging the third group lens frame 51 and the lens frame 151 in the direction along the photographing optical axis O also applies a load in the direction orthogonal to the moving direction. Accordingly, backlash removal is performed in the advance / retreat guide mechanism of the third group lens frame 51 and the lens frame 151.

  The urging arm portion 38c of the third group lens urging spring 38 in the first embodiment is indicated by a solid line in FIGS. 10 and 11 in an applied state in which the urging arm portion 38c is engaged with the spring hooking protrusion 51h of the third group lens frame 51. It extends along a swinging plane (swinging surface) orthogonal to the swinging center axis 38x, and when the third lens group frame 51 moves along the photographing optical axis O as described above, It is swung. In a free state where the urging arm portion 38c is not engaged with the spring hooking projection 51h of the third group lens frame 51, the urging arm portion 38c is not parallel to the oscillating plane (as shown by a two-dot chain line in FIGS. 10 and 11). It is located outside the moving surface) and has a tilted shape inclined in a direction approaching the photographing optical axis O. When the biasing arm portion 38c is brought into an applied state to engage with the spring hooking protrusion 51h, the biasing arm portion 38c is elastically counterclockwise in FIGS. 10 and 11 so as to approach the swinging plane. It is deformed and brought into contact with a standing wall portion (contact portion) 51k formed in the third group lens frame 51 to restrict the return to the free state. The standing wall portion 51k has a planar shape that is substantially parallel to the swinging plane of the urging arm portion 38c, and a semicircular cross-sectional portion 51m that abuts against the urging arm portion 38c is formed on one side surface thereof. The aforementioned spring-hanging projection 51h is provided in front of the semicircular cross-section 51m.

  When the urging arm portion 38c is elastically deformed from the free state and brought into contact with the standing wall portion 51k (semicircular cross-section portion 51m), the standing wall portion 51k of the third group lens frame 51 is caused by the force to return from the bending deformation. Is pushed toward the right in the figure. The standing wall portion 51k is provided at a position immediately below the guide hole 51d at the tip of the guide arm portion 51b of the third group lens frame 51, and the load input from the urging arm portion 38c to the standing wall portion 51k is as follows. The guide hole 51d acts as a pressing force to displace the guide hole 51d in the right direction in FIGS. As a result, the inner wall of the guide hole 51d is pressed against the third group guide shaft 52, and the relationship between the guide hole 51d and the third group guide shaft 52 is orthogonal to the moving direction of the third group lens frame 51 (the direction along the photographing optical axis O). Play in the direction to do is eliminated. A moment also acts on the rotation restricting projection 51e and the rectilinear guide groove 22f that are symmetrical with the guide hole 51d and the third group guide shaft 52 across the photographing optical axis O, and a pair of rectilinear guide grooves 22f. The rotation restricting projection 51e is pressed against one of the opposing guide surfaces to remove play. Therefore, the third group lens frame 51 is stably held without causing a position change due to the clearance of the advance / retreat guide mechanism. Since the urging force from the urging arm portion 38c to the standing wall portion 51k is always applied while the third group lens urging spring 38 is in the applied force state, the third group lens frame 51 can be moved to any position. Stable retention is maintained. Accordingly, it is possible to smoothly move the third group lens frame 51 without causing rattling or abnormal noise. Further, the positional accuracy of the third group lens frame 51 in a plane orthogonal to the photographing optical axis O in a state where the third group lens frame 51 is stopped is improved. The standing wall portion 51k and the semicircular cross-sectional portion 51m of the third group lens frame 51 have the urging arm portion 38c at another portion when the urging arm portion 38c is engaged with the spring hooking projection 51h. It also has a protective function to prevent contact.

  As described above, the urging means for applying the urging force in the direction perpendicular to the moving direction of the third group lens frame 51 to the standing wall 51k applies the third group lens frame 51 in the direction along the photographing optical axis O. Since it is the same as the third group lens urging spring 38 (the urging arm portion 38c) to be urged, the third group lens frame 51 and its Backlash removal can be performed between the third group guide shaft 52 and the straight guide groove 22f that carry the advance / retreat guide.

  Similar to the urging arm portion 38c of the third group lens urging spring 38 of the first embodiment, the urging arm portion 138c of the lens frame urging spring 138 in the second embodiment is also a spring hooking projection of the lens frame 151. In a free state in which it is not engaged with 151c, as shown by a two-dot chain line in FIG. 16, it tilts in a direction approaching the photographing optical axis O with respect to a position on the swing plane in the applied force state indicated by a solid line in FIG. It has a different shape. Then, when the biasing arm portion 138c is brought into an applied state to be engaged with the spring hooking protrusion 151c, the outer surface of the cylindrical portion 151a of the lens frame 151 is elastically deformed in the clockwise direction in FIG. The portion (contact portion) is pressed in the left direction in FIG. This pressing force prevents the lens frame 151 from rattling with respect to the guide shaft 152 and stabilizes the position of the lens group LG in a plane orthogonal to the photographing optical axis O. That is, the lens frame urging spring 138 has both a function of urging the lens frame 151 in its moving direction and a function of urging the lens frame 151 in a direction orthogonal to the moving direction, and has a small number of parts. The lens frame 151 can be stably held with a simple and space-saving configuration.

  The swing lever 70 of the third to fifth embodiments is also configured to apply a load to the third group lens frame 51 in a direction orthogonal to its moving direction. As described in the third embodiment, the swing lever 70 can be elastically deformed in a direction orthogonal to the photographing optical axis O, and is free to engage with the spring projection 51h of the third group lens frame 51. In the state, as shown by a two-dot chain line in FIGS. 17 and 18, a tilted shape tilted in a direction approaching the photographing optical axis O with respect to the position on the swing plane in the applied force state shown by the solid line in FIG. It has become. The swing lever 70 is elastically deformed counterclockwise in FIG. 17 and FIG. 18 when it is in an applied force state to engage with the spring hooking protrusion 51h, and the standing wall portion 51k (semicircle) of the third group lens frame 51. The standing wall 51k is pressed toward the right in the figure by a force which is brought into contact with the section 51m) and tries to release its deformation. This pressing force prevents the third group lens frame 51 from rattling with respect to the third group guide shaft 52 and the rectilinear guide groove 22f, and stabilizes the position of the third lens group LG3 in a plane orthogonal to the photographing optical axis O. In other words, the swing lever 70 receives the biasing force of the torsion spring 238 and moves the third group lens frame 51 by the function of biasing the third group lens frame 51 in its moving direction and the elastic deformation of the swing lever 70 itself. The third group lens frame 51 can be stably held with a simple and space-saving configuration with a small number of parts. Although a detailed description is omitted, the swing lever 70 in the fourth and fifth embodiments similarly has a complex function of urging the third group lens frame 51 in two different directions.

  22 to 26 show modified examples that are more effective in applying an urging force in a direction orthogonal to the moving direction to the holding member of the optical element. In this modification, a part of the configuration of the first embodiment described above is made different, and description of portions common to the above-described portions is omitted.

  22 and 23 show a first modification. The lens barrel rear surface plate 23 holds a CCD 24 and closes the rear surface of the cylindrical housing portion (pressing means, fixed wall member, inner wall member, inner cylindrical member) 22a of the fixed lens barrel 22, and the main body portion. It has a protective wall part (pressing means, fixed wall member, outer wall member) 23b extending forward from the optical axis direction 23a. The protective wall portion 23b faces the outer peripheral surface of the cylindrical housing portion 22a and forms a storage space Q therebetween. A third group lens biasing spring 38 is held in the storage space Q. As described above, the urging arm portion 38c of the third group lens urging spring 38 is in a tilted shape inclined in a direction approaching the photographing optical axis O as shown by a two-dot chain line in FIG. In the state of the applied force engaged with the spring hooking protrusion 51h of the third lens group frame 51, it is elastically deformed as indicated by the solid line in FIG. In this applied state, a spring pressing portion (projecting pressing portion) 23c that contacts the urging arm portion 38c is formed on the protective wall portion 23b of the lens barrel rear surface plate 23. As shown in FIG. 22, the spring pressing portion 23 c protrudes from the surface of the protective wall portion 23 b that faces the storage space Q (that is, the side facing the outer peripheral surface of the cylindrical housing portion 22 a). This is a rib-shaped projection that is long in the direction, and maintains contact with the urging arm portion 38c when the third lens group frame 51 is in any position within the movable range in the optical axis direction.

  The amount of protrusion of the spring pressing portion 23c is set so as to give a pressing force toward the standing wall portion 51k (semicircular cross-section 51m) when the urging arm portion 38c is engaged with the spring hooking projection 51h. ing. Therefore, the third group lens biasing spring 38 can reliably apply a biasing force in a direction orthogonal to the moving direction of the third group lens frame 51, and the third group guide which is an advance / retreat guide portion of the third group lens frame 51. The play between the shaft 52 and the guide hole 51d can be removed satisfactorily.

  FIG. 24 shows a second modification. The pressing force by the spring pressing portion 23c provided on the protective wall portion 23b of the lens barrel rear surface plate 23 is applied to the urging arm portion 38c of the third group lens urging spring 38 in the applied state shown by the solid line in FIG. This is common to the first modification. This modification is different in that the cylindrical housing portion 22a ′ of the housing 22 is not a complete cylindrical body but an incomplete cylindrical body in which a portion facing the protective wall portion 23b is missing. Accordingly, the coil portion 38a of the third group lens urging spring 38 is held by the spring retaining screw 39 'on the spring support protrusion 23d provided on the protective wall portion 23b side, not on the cylindrical housing portion 22a' side. Yes. Thus, in this invention, the cylindrical member (cylindrical housing part 22a ') located inside an urging | biasing means does not need to be perfect cylinder shape, In that case, the outer side wall member (protection) in the outer side It is effective to provide a pressing portion for the urging means (the third group lens urging spring 38) on the wall 23b).

  FIG. 25 shows a third modification. In this modification, the urging force in the direction orthogonal to the moving direction of the third lens group frame 51 is applied by applying the urging arm portion 38c of the third lens group urging spring 38 to the protective wall 23b of the lens barrel rear plate 23. Is the same as the first and second modified examples described above, but is different depending on the shape of the urging arm portion 38c. That is, the urging arm portion 38c includes an outward extending portion 38c-1 extending in a direction approaching the protective wall portion 23b from the coil portion 38a (a direction away from the cylindrical housing portion 22a), and the outward extending portion 38c. -1 and a bent portion 38c-2, and an inwardly extending portion 38c-3 extending from the bent portion 38c-2 in a direction approaching the cylindrical housing portion 22a (a direction away from the protective wall portion 23b). It has a bent shape that is convex toward the wall 23b. Then, when the urging arm portion 38c is elastically deformed from the free state indicated by the two-dot chain line in FIG. 25 to the applied state indicated by the solid line, the bent portion 38c-2 is pressed against the protective wall portion 23b. Then, due to the reaction force against the pressing, the inwardly extending portion 38c-3 of the urging arm portion 38c becomes the standing wall portion 51k (semicircular cross-sectional portion 51m) side, as in the case of the first and second modifications. It is pushed toward.

  In the fourth modified example shown in FIG. 26, contrary to the first to third modified examples, not the protective wall portion 23 b of the lens barrel rear surface plate 23, but the cylindrical housing portion 22 a side of the fixed barrel 22, A pressing portion for the urging arm portion 38c of the third group lens urging spring 38 is provided. In this modification, the urging direction of the urging arm portion 38c with respect to the advance / retreat guide portion (the third group guide shaft 52 and the guide hole 51d) of the third group lens frame 51 is opposite to that shown in FIGS. When the urging arm portion 38c is elastically deformed from the free state indicated by a two-dot chain line in FIG. 26 to the applied state to the spring hooking protrusion 51h indicated by the solid line, the urging arm portion 38c is closer to the photographing optical axis O. The standing wall 51k ′ (semicircular cross-section 51m ′) provided at the end of the spring-hanging projection 51h is pressed toward the side away from the head. On the outer peripheral surface of the cylindrical housing portion 22a, there is formed a spring pressing portion (projecting pressing portion) 22r that protrudes into the storage space Q (the approaching direction to the protective wall portion 23b). Then, the protective wall 23b in the applied state is pressed in the approaching direction to the standing wall 51k ′ (semicircular cross-section 51m ′). Therefore, also in the third modification, the urging force in the direction orthogonal to the moving direction of the third group lens frame 51 can be reliably applied by the urging arm portion 38c of the third group lens urging spring 38.

  In the aspect in which the urging arm portion 38c is pressed by the cylindrical housing portion 22a, the urging arm portion 38c may have a bent shape as in the third modification. That is, in FIG. 25, the urging arm portion 38c has a bent shape that is convex toward the protective wall portion 23b. On the contrary, the urging arm portion 38c is directed toward the cylindrical housing portion 22a. It is also possible to adopt a mode in which a convex bent shape is formed and the bent portion is applied to the cylindrical housing portion 22a. However, in order to ensure stability when the bent portion of the urging arm portion 38c is applied, a specific pressing portion such as a spring pressing portion 22r may be provided on the outer peripheral surface of the cylindrical housing portion 22a. preferable.

  The above modification is applied to the urging arm portion 38c of the third group lens urging spring 38 of the first embodiment, but the urging arm portion of the lens frame urging spring 138 of the second embodiment. The same applies to 138c and the swing lever 70 of the third to fifth embodiments. In the applied state, the biasing arm portion 138c and the swing lever 70 are pressed in a direction orthogonal to the moving direction by the advance / retreat guide member (the third group guide shaft 52, the guide shaft 152), thereby preventing backlash of the advance / retreat guide portion. A higher effect can be obtained.

  As mentioned above, although embodiment of this invention was described with reference to illustration embodiment, this invention is not limited to this embodiment. For example, in the illustrated embodiment, the optical element moved forward and backward in the optical axis direction is the focusing lens group, but the present invention can also be applied as a position control mechanism for optical elements other than the focusing lens group. .

  Further, the support arm portion 38b of the third group lens biasing spring 38 in the first embodiment, the support arm portion 238b of the torsion spring 238 in the third embodiment, and the tension springs 338, 438 in the fourth and fifth embodiments. One end of each is engaged with a protrusion provided on the fixed lens barrel 22, but the object with which one end of the spring constituting the urging means is engaged corresponds to at least the third group lens frame 51. As long as relative movement occurs between the members, the movable member is not limited to a fixed member. Similarly, the support member that pivotally supports the lever member 70 in the third to fifth embodiments is not limited to a fixed member such as the fixed barrel 22, and is at least a holding member corresponding to the third group lens frame 51. Any device that causes relative movement between them may be used.

  In each of the above embodiments, the urging arm portion 38c of the third group lens urging spring 38, the urging arm portion 138c of the lens frame urging spring 138, and the swing lever 70, which constitute the urging means, are all linear. In the applied state with respect to the third group lens frame 51 and the lens frame 151, the urging arm portions 38c and 138c and the swing lever 70 are constant around the swing center axes 38x, 138x and 70x. It is swung in the swing plane. However, in the present invention, the urging portion (swinging portion) of the urging means is not limited to such a linear body, and various types such as a bent urging arm portion 38c shown in FIG. It is possible to take various forms. If the applied portion is not a simple linear body or has an inclination with respect to the direction orthogonal to the oscillation center axis even in the applied state, the locus during the oscillation will be within a simple plane. Although it is not a thing, if attention is paid to a specific portion of the applied force portion, it can be considered that the portion is moved within a certain plane centered on the oscillation central axis. In the present invention, a plane perpendicular to the swing central axis that includes the movement locus of the specific part is defined as a swing plane.

It is sectional drawing which shows the accommodation state of the zoom lens barrel to which the optical element position control mechanism of this invention is applied. It is sectional drawing of the imaging state of the zoom lens barrel. It is a front perspective view of the storage state of the zoom lens barrel. It is a back perspective view of the storage state of the zoom lens barrel. It is a front perspective view of the photographing state of the zoom lens barrel. It is the back perspective view which removed the barrel back plate in the photography state of the zoom lens barrel. It is a back perspective view of the state where a member related to position control of the 3rd lens group was removed from a zoom lens barrel. It is a front perspective view which shows the principal part of a 3 group lens frame and its position control mechanism. It is a back perspective view which shows the principal part of a 3 group lens frame and its position control mechanism. It is a front view of a zoom lens barrel mainly showing a third group lens frame and its position control mechanism. It is the front view which took out and showed only the 3 group lens frame and its position control mechanism from FIG. It is a side view of the 3rd group lens frame and its position control mechanism which shows the operation of the 3rd group lens energizing spring. It is a side view of a 3 group lens frame and its position control mechanism in a comparative example using a tension spring as a 3 group lens urging spring. It is a graph for comparing the fluctuation | variation of the spring load by embodiment of FIG. 12, and the comparative example of FIG. 13, (a) is embodiment, (b) shows a comparative example. It is a side view of the position control mechanism of the lens group which shows 2nd Embodiment using a lead cam shaft instead of the feed screw mechanism of 1st Embodiment. It is a front view of the position control mechanism of the lens group in 2nd Embodiment of FIG. FIG. 10 is a front view of a zoom lens barrel mainly including a third group lens frame and its position control mechanism, showing a third embodiment using a lever member and a torsion spring as a biasing means for the third group lens frame. It is the front view which took out and showed only the 3 group lens frame and its position control mechanism from FIG. It is a side view of the 3rd group lens frame and its position control mechanism which shows an operation of a lever member and a torsion spring in a 3rd embodiment. It is a side view of a 3 group lens frame and its position control mechanism which shows a 4th embodiment using a lever member and a tension spring as urging means of a 3 group lens frame. It is a side view of a 3 group lens frame and its position control mechanism which shows a 5th embodiment using a lever member and a tension spring as a biasing means of a 3 group lens frame. It is a perspective view of a lens barrel rear plate showing a first modification in which a pressing portion against a biasing arm portion of a third group lens biasing spring is provided on the protective wall portion of the lens barrel rear plate. In a 1st modification, it is the rear view which made the section a part which shows the state which has pressed the urging | biasing arm part of the 3 group lens urging | biasing spring with the press part of the protection wall part of a lens-barrel rear surface plate. In the 2nd modification, it is the rear view which made the section a part which shows the state where the energizing arm part of the 3rd group lens energizing spring is pressed by the press part of the protection wall part of the barrel back plate. In the 3rd modification, it is a rear view which made the section into a section showing the state where the bent part formed in the energizing arm part of the 3 group lens energizing spring is pressed by the protection wall part of the barrel back plate is there. In the 4th modification, it is the rear view which made the section a part showing the state where the energizing arm part of the 3rd group lens energizing spring is pressed by the press part provided in the cylindrical housing part of the fixed barrel is there.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Zoom lens barrel 11 Cam ring 12 2nd delivery cylinder 13 1st delivery cylinder 22 Fixed barrel (support member)
22a Tubular housing (fixed wall member, inner wall member, inner tubular member)
22a 'cylindrical housing portion 22b zoom motor support portion 22c AF motor support portion 22d front wall portion 22e opening 22f rectilinear guide groove 22g cam ring control groove 22h 22i rectilinear guide groove 22j spring support projection 22k 22n fixed projection 22m swing support projection 22m Spring hooking protrusion 22p 22q Spring hooking protrusion 22r Spring pressing part (protruding pressing part)
23 Lens barrel rear plate 23b Protective wall (fixed wall member, outer wall member)
23c Spring pressing part (protruding pressing part)
23d Spring support projection 24 CCD
30 AF motor 32 Zoom motor 36 Feed screw 37 AF nut 38 Third lens group biasing spring (biasing means, spring member)
38a Coil portion 38b Support arm portion (second arm portion)
38c Energizing arm (urging means, first arm)
38c-1 Outwardly extending portion 38c-2 Bending portion 38c-3 Inwardly extending portion 38x Oscillation center shaft 39 39 'Spring retaining screw 40 Origin position detection sensor 51 Third group lens frame (optical element holding member)
51a Lens holding part 51b 51c Guide arm part 51d Guide hole 51e Rotation restricting protrusion 51f Nut abutting part 51g Non-rotating protrusion 51h Spring hooking protrusion (protrusion part)
51i Sensor passage plate 51j Lever engagement protrusion 51k 51k 'Standing wall portion 51m 51m' Semicircular cross section 52 Third group guide shaft (advance / retreat guide member)
70 Swing lever (biasing means, lever member)
70a Main arm 70b 70c Spring hook arm 70x Oscillating center shaft 122j Spring support projection 122k Fixed projection 130 Motor 136 Lead cam shaft 136a Lead groove 138 Lens frame biasing spring (biasing means, spring member)
138a Coil part 138b Support arm part 138c Energizing arm part (urging means)
138x Oscillation center axis 151 Lens frame (holding member for optical element)
151a Cylindrical part 151b Guide pin 151c Spring hooking protrusion (protrusion part)
151d Non-rotating groove 152 Guide shaft (advance / retreat guide member)
153 Non-rotating shaft 238 Torsion spring 238a Coil portion 238b Support arm portion 238c Energizing arm portion 338 Tension spring 438 Tension spring LG Lens group LG1 First lens group LG2 Second lens group LG3 Third lens group LPF Low pass filter O Shooting optical axis Q Storage space S Shutter

Claims (12)

A holding member for holding the optical element;
An advancing / retreating guide member that supports the holding member so as to be movable in an optical axis direction passing through the optical element;
A biasing force in a moving direction guided by the advance / retreat guide member with respect to the holding member and swingable in the optical axis direction in an applied state engaging with the holding member, and a direction orthogonal to the moving direction An optical element position control mechanism comprising: an urging unit that simultaneously applies an urging force to the lens. 2. The optical element position control mechanism according to claim 1, wherein the biasing unit is a coil portion supported by a support member different from the holding member with an axis line oriented in a direction orthogonal to the optical axis direction, and the coil A first arm portion extending from the portion toward the outer diameter direction and engaging with the holding member; and a second arm portion extending from the coil portion toward the outer diameter direction and engaged with the support member. And a spring member that changes the amount of bending in the rotational direction around the coil portion according to the movement of the holding member, and the first arm portion of the spring member is free to engage with the holding member. An optical element position control mechanism that is positioned outside the rocking surface defined by the rocking movement and is elastically deformed in a direction approaching the rocking surface when it is in a state of being applied to the holding member. 2. The optical element position control mechanism according to claim 1, wherein the urging means has one end portion pivotally supported by a support member different from the holding member and the other end portion engaged with the holding member, and the swing center. In a free state where the lever member is not engaged with the holding member, the lever member is biased in either the forward or reverse rotational direction to the outside of the swing surface defined by the swing. An optical element position control mechanism that is positioned and elastically deformed in a direction approaching the rocking surface when the holding member is in an applied state. 4. The optical element position control mechanism according to claim 1, wherein the advance / retreat guide member is a guide shaft whose axis is directed in the optical axis direction, and the holding member is slidable on the guide shaft. An optical element position control mechanism that has a guide hole to be inserted, and the urging means presses the inner wall of the guide hole of the holding member against the guide shaft by pressing against a contact portion in the vicinity of the guide hole. 5. The optical element position control mechanism according to claim 4, wherein the holding member protrudes from an abutting portion in the vicinity of the guide hole and is positioned on an extension of the swinging direction of the biasing member to generate a biasing force in the moving direction. An optical element position control mechanism having a receiving projection. The optical element position control mechanism according to any one of claims 1 to 5, further comprising: a pressing unit that presses the biasing unit in a direction perpendicular to a moving direction of the holding member in an applied state to the holding member. An optical element position control mechanism. 7. The optical element position control mechanism according to claim 6, wherein the pressing means has a fixed wall member positioned on at least one of the outer side and the inner side of the biasing means, and the biasing means contacts the fixed wall member. An optical element position control mechanism that contacts and is pressed in a direction orthogonal to the moving direction of the holding member. 8. The optical element position control mechanism according to claim 7, wherein the fixed wall member is an outer wall member positioned outside the biasing means, and presses the biasing means in a direction approaching the optical axis. mechanism. 8. The optical element position control mechanism according to claim 7, wherein the fixed wall member is an inner wall member positioned inside the biasing means, and presses the biasing means in a direction away from the optical axis. mechanism. 10. The optical element position control mechanism according to claim 7, wherein the fixed wall member has a projecting pressing portion that comes into contact with the urging means. 11. 11. The optical element position control mechanism according to claim 7, wherein the urging means has a bent shape that is convex toward the fixed wall member, and the bent portion contacts the fixed wall member. Optical element position control mechanism in contact. The optical element position control mechanism according to claim 6, further comprising: an inner cylindrical member positioned outside the holding member; and an outer wall member facing the outer surface of the inner cylindrical member;
The urging means is held between the inner cylindrical member and the outer wall member, and abuts against either the inner cylindrical member or the outer wall member and is pressed in a direction orthogonal to the moving direction of the holding member. Optical element position control mechanism.

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