JP2009116222A - Mechanism for controlling position of optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mechanism for controlling the position of an optical element, which is configured in space saving, and achieves miniaturization and power-saving, wherein the fluctuations of loads accompanying in the movement of a reciprocating member is small. <P>SOLUTION: The mechanism for controlling the position of the optical element includes: a reciprocating member which holds the optical element and is supported so as to move in an optical axis direction passing through the optical element; a driving mechanism for reciprocating the reciprocating member in the optical axis direction; and a biasing means swingable in the optical axis direction, having a swing force receiving section that engages with the reciprocating member in the position away from the center of the swinging, and biasing the reciprocating member in the optical axis direction through the swing force receiving section. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a position control mechanism for an optical element in an optical apparatus, and more particularly to a structure that applies an urging force in the moving direction to an advancing / retreating member that moves forward / backward in the optical axis direction.

In an optical device such as a camera, the advancing / retracting member that holds the optical element and can move in the optical axis direction performs a part of the function of the driving mechanism, takes backlash in the driving mechanism, or positions the moving member. For the purpose of stabilization, an urging force in the direction of the optical axis is often given. The urging means for the advance / retreat member is generally constituted by a tension spring or a compression spring having an axis line in the optical axis direction.
JP 2000-206391 A

  In an arrangement structure of a tension spring or a compression spring that has been widely used as an urging means for the advance / retreat member, one end of the spring is engaged with the advance / retreat member, and the other end is integrated with the advance / retreat member such as a fixing member. It is engaged with another support member that is not moved, and the amount of movement of the advance / retreat member is directly reflected in the amount of expansion / contraction of the spring. As the amount of expansion / contraction of the spring increases, the fluctuation range of the load increases accordingly.

  By the way, the output of the motor or actuator constituting the drive mechanism of the advance / retreat member is set so as to correspond to the maximum load of the urging means for the advance / retreat member. That is, if the maximum load of the urging means is increased, a stronger drive source is required, which is disadvantageous in terms of power consumption, manufacturing cost, and miniaturization. However, in the conventional arrangement structure of the tension spring and the compression spring with respect to the advancing / retreating member, the amount of spring expansion / contraction per movement of the advancing / retreating member, that is, the fluctuation range of the load tends to increase, and it is difficult to keep the maximum load small.

  In tension springs and compression springs, the fluctuation range of the load with respect to a certain amount of movement of the advance / retreat member can be relatively reduced by extending the spring length. However, it is difficult to extend the length of the spring in the recent optical equipment, which has a strong demand for miniaturization, because it goes against space saving. In particular, zoom lens barrels are strongly demanded to be compact in the stowed state when shooting is not performed, and when stowed, the distance between the optical elements in the optical system in the optical axis direction is reduced as much as possible to shorten the barrel. There are many structures to make. Therefore, the spring length in the moving direction of the advancing / retreating member is limited by the thickness of the lens barrel in this shortened state, and it is difficult to adopt a long spring. As a result, the above-described problem that the load fluctuation of the spring becomes large tends to occur.

  In addition, even if the movement amount of the advance / retreat member itself is reduced, the fluctuation range of the load due to the biasing means can be suppressed. However, the advance / retreat member, that is, the movement amount of the optical element, originally satisfies the required optical performance. If the amount of movement is limited, the required optical performance may not be obtained. For example, in the zoom lens barrel that aims to reduce the size of the optical system in the optical axis direction as much as possible in the housed state as described above and aim for high zooming, the amount of movement of the advancing / retracting member that holds the optical element increases. There is a tendency.

  Therefore, the present invention has an object to provide an optical element position control mechanism that can be configured in a space-saving manner, has a small variation in load accompanying the movement of the advancing / retreating member, and achieves both miniaturization and power saving at a high level. And

  An optical element position control mechanism according to the present invention includes an advance / retreat member that holds an optical element and is movably supported in the optical axis direction passing through the optical element, a drive mechanism that moves the advance / retreat member in the optical axis direction, and It has a swinging force force portion that can swing in the optical axis direction and engages the advancing / retreating member at a position away from the center of swinging, and urges the advance / retreat member in the optical axis direction via the swinging force force portion. And an urging means for performing the operation.

  As one aspect of the urging means, a coil part supported by a support member different from the advance / retreat member with the axis line oriented in a direction orthogonal to the optical axis direction, and extended / retracted from the coil part toward the outer diameter direction A first arm portion that engages with the member, and a second arm portion that extends from the coil portion toward the outer diameter direction and engages with the support member, and the coil portion according to the movement of the advance / retreat member The urging means can be constituted by a spring member that changes the amount of bending in the rotational direction around the center,

  In this case, the spring member that constitutes the urging means determines the amount of displacement in the rotational direction of the first arm portion from the free state where the spring member is not engaged with the advance / retreat member to the applied state where it is engaged with the advance / retreat member. The amount of displacement of the first arm portion in the rotational direction due to the advance / retreat movement of the advance / retreat member in the state of being applied to the head is preferably larger.

  As another aspect of the urging means, a lever member whose one end is pivotally supported by a support member different from the advance / retreat member and the other end engages with the advance / retreat member is provided as the swinging force applying portion, and the lever member is further swung. A configuration in which a lever urging member that urges the moving center in either the forward or reverse rotation direction is also possible.

  The lever urging member in this aspect includes a coil portion supported by the support member with the axis line oriented in a direction orthogonal to the optical axis direction, and a first arm portion extending from the coil portion and engaged with the lever member. And a second arm portion that extends from the coil portion and engages with a spring hook portion of the support member, and in accordance with the swing of the lever member, the amount of bending in the rotational direction around the coil portion It is possible to configure with a spring member to be changed.

  Alternatively, the lever urging member may be configured by an extension spring that has one end engaged with the lever member and the other end engaged with the support member and changes its length in accordance with the swing of the lever member. In this case, the length from the swing center of the lever member to the spring hooking portion of the extension spring may be shorter than the length from the swing center to the engagement position with the advance / retreat member.

  The present invention further includes a rotating frame that surrounds the optical axis of the optical element held by the advance / retreat member and moves an optical element different from the optical element by rotation, and the drive mechanism and biasing means of the advance / retreat member are respectively It is preferable that the rotary frame is disposed on the outer side in the radial direction. Thereby, the biasing means can be configured without being restricted by a movable member such as a rotating frame. Further, as the arrangement of the urging means, the engagement position of the swinging force applying portion with respect to the swinging center and the advancing / retracting member is substantially parallel to the swinging center axis of the swinging force applying unit on the outside of the rotating frame, and the advancing / retracting member is If the two regions divided by the plane including the optical axis passing through the holding optical element are divided into one and the other, it is effective in suppressing the load fluctuation width of the urging means, and space efficiency is reduced. Can be increased.

  In the present invention, various types of drive mechanisms for the advancing and retracting members can be used. For example, a feed screw that rotates about an axis parallel to the optical axis direction, and a nut that is screwed into the feed screw and is advanced and retracted in the optical axis direction by forward and reverse rotation of the feed screw. In a drive mechanism in which the movement position of the advance / retreat member in the optical axis direction is determined by contact, the urging means for the advance / retreat member functions to maintain the contact state with the nut and cause the nut to follow the advance / retreat member. To do.

  Further, in a drive mechanism of a type having a guide member having a guide surface having an inclination component with respect to the optical axis direction and a follower projecting on the advance / retreat member and slidingly contacting the guide surface of the guide member, an urging means for the advance / retreat member Can perform the function of removing the backlash by pressing the follower against the guide surface.

  According to the present invention as described above, an optical element position control mechanism that can be configured in a space-saving manner, has a small variation in the load of the urging means accompanying the movement of the advancing / retreating member, and achieves both miniaturization and power saving at a high level. Can be obtained.

  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, and an AF motor support portion 22c that supports an AF motor (drive mechanism) 30. And a front wall portion 22d positioned in front of the AF 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 (advancing / retracting 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 symmetric 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. The shaft 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 portion of the cam ring (rotating frame) 11 that is supported inside the cylindrical housing portion 22 a of the fixed barrel 22, and the cam ring 11 is interposed via the zoom gear 31. The zoom motor 32 is rotationally driven. 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. This is transmitted to a feed screw (drive mechanism) 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 (drive mechanism) 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, a standing wall portion 51k having a planar shape substantially parallel to the photographing optical axis O is formed at the distal end portion of the guide arm portion 51b of the third group lens frame 51, and is positioned between the pair of front and rear guide holes 51d. A spring-hanging projection 51h is provided so as to project from the standing wall 51k to the side. The spring hooking protrusion 51h is an L-shaped protrusion whose tip is bent toward the rear in the optical axis direction. A semicircular cross-sectional portion 51m is formed on the standing wall portion 51k so as to be located behind the spring hooking projection 51h.

  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 (second arm) 38b and a long biasing arm (first arm) 38c extending from the coil portion 38a in the outer diameter direction. I am letting. 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. When the urging arm portion 38c of the standing wall portion 51k and the semicircular cross-sectional portion 51m of the third group lens frame 51 is engaged with the spring hooking projection 51h, the urging arm portion 38c comes into contact with other parts. To prevent. 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. A lead cam shaft (drive mechanism, guide member) 136 is used in place of the feed screw as the drive mechanism of the lens frame (advance / retreat member) 151 that holds the lens. The lens frame 151 has a guide shaft 152 slidably inserted into a guide hole formed in the cylindrical portion 151a, and a detent formed at a substantially symmetrical position with the cylindrical portion 151a and the photographing optical axis O interposed therebetween. A non-rotating shaft 153 is slidably engaged with the groove 151d so as to be guided in a straight line in a direction parallel to the photographing optical axis O and guided from the cylindrical portion 151a receiving the guide shaft 152. (Drive mechanism, follower) 151b is projected. 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 (driving mechanism) 130 via the gear 135, the lead cam shaft 136 is rotated by a rotation center parallel to the photographing optical axis O. Driven. 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 supporting arm portion (second arm portion) 138b is engaged with the fixing protrusion 122k, and the other biasing arm portion (first arm portion) 138c is engaged with the spring hooking protrusion 151c of the lens frame 151. I am letting. 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 advance / retreat member in the present invention is not limited to the one directly involved in driving the advance / retreat member as in the first embodiment, but the lens frame. It may be for backlash removal such as a biasing spring 138. The drive mechanism for the advancing / retracting 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 the requirement that the urging force is applied to the advance / retreat member via the swinging force applying portion that oscillates in the direction of the optical axis passing through the optical element held by the advance / retreat 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 urging means for the third group lens frame 51 is composed of a oscillating lever (oscillating force portion, lever member) 70 and a torsion spring (lever urging member) 238. is doing. 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 protrusion 22n of the fixed barrel 22 with the support arm portion (second arm portion) 238b extending from the coil portion 238a in the outer diameter direction, and the biasing arm portion (first arm portion) The arm portion 238c is engaged in the vicinity of the shaft support portion of the swing lever 70, and the swing 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 (lever urging member, expansion / contraction spring) 338 as the urging member for the swing lever 70 employed in the third embodiment. is there. 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 of FIG. 21 is obtained by replacing the tension spring 338 of the fourth embodiment with a tension spring (lever urging member, expansion / contraction 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 70c and the other end engaged with a spring protrusion 22q 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.

  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 to which one end of the spring constituting the urging means is engaged is at least advancing and retracting corresponding to 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 lens barrel 22, and is a forward / backward member corresponding to at least the third group lens frame 51. Any device that causes relative movement between them may be used.

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.

Explanation of symbols

1 Zoom lens barrel 11 Cam ring (rotating frame)
12 Second feeding cylinder 13 First feeding cylinder 22 Fixed lens barrel (supporting member)
22a Tubular housing portion 22b Zoom motor support portion 22c AF motor support portion 22d Front wall portion 22e Opening portion 22f Straight guide groove 22g Cam ring control groove 22h 22i Straight guide groove 22j Spring support projection 22k 22n Fixed projection 22m Swing support projection 22p 22q Spring projection 23 Lens barrel rear plate 24 CCD
30 AF motor (drive mechanism)
32 Zoom motor 36 Feed screw (drive mechanism)
37 AF nut (drive mechanism)
38 3 group lens biasing spring (biasing means, spring member)
38a Coil portion 38b Support arm portion (second arm portion)
38c Energizing arm portion (swinging force applying portion, first arm portion)
38x Oscillation center shaft 39 Spring retaining screw 40 Origin position detection sensor 51 Third lens group frame (advance / retreat member)
51a Lens holding portion 51b 51c Guide arm portion 51d Guide hole 51e Rotation restricting projection 51f Nut abutting portion 51g Non-rotating projection 51h Spring projection 51i Sensor passage plate 51j Lever engagement projection 52 Third group guide shaft 70 Oscillating lever (Force force part, lever member)
70a Main arm 70b 70c Spring hook arm 70x Oscillation center shaft 122j Spring support protrusion 122k Fixed protrusion 130 Motor (drive mechanism)
136 Lead cam shaft (drive mechanism, guide member)
136a Lead groove (guide surface)
138 Lens frame biasing spring (biasing means, spring member)
138a Coil portion 138b Support arm portion (second arm portion)
138c Energizing arm portion (swinging force applying portion, first arm portion)
138x Oscillation center shaft 151 Lens frame (advance / retreat member)
151a Cylindrical portion 151b Guide pin (drive mechanism, follower)
151c Spring hooking projection 152 Guide shaft 153 Non-rotating shaft 238 Torsion spring (lever urging member)
238a Coil part 238b Support arm part (second arm part)
238c Energizing arm (first arm)
338 Tension spring (lever biasing member, expansion spring)
438 Tension spring (lever biasing member, expansion spring)
LG lens group LG1 first lens group LG2 second lens group LG3 third lens group LPF low pass filter O photographing optical axis S shutter

Claims (11)

An advancing and retracting member that holds the optical element and is movably supported in the optical axis direction passing through the optical element;
A drive mechanism for moving the advance / retreat member back and forth in the optical axis direction;
A swing attachment portion that is capable of swinging in the direction of the optical axis and that engages the advance / retreat member at a position away from the center of the swing, and the advance / retreat member is connected to the optical axis via the swing attachment portion. An optical element position control mechanism comprising an urging means for urging in a direction. 2. The optical element position control mechanism according to claim 1, wherein the biasing means is a coil portion supported by a support member different from the advance / retreat member with an axis line oriented in a direction orthogonal to the optical axis direction, and the coil A first arm that extends from the coil portion toward the outer diameter direction and engages with the advance / retreat member, and a second arm that extends from the coil portion toward the outer diameter direction and engages with the support member The optical element position control mechanism which consists of a spring member which has a part and changes the deflection amount of the rotation direction centering on a coil part according to the movement of an advance / retreat member. 3. The optical element position control mechanism according to claim 2, wherein the spring member is rotated in a rotational direction of the first arm portion from a free state where the spring member is not engaged with the advance / retreat member to an applied state where the spring member is engaged with the advance / retreat member. An optical element position control mechanism in which the amount of displacement is larger than the amount of displacement in the rotational direction of the first arm portion due to the advance / retreat movement of the advance / retreat member in a state where the advance / retreat member is applied. 2. The optical element position control mechanism according to claim 1, wherein one end of the oscillating force portion of the urging means is pivotally supported by a support member different from the advance / retreat member and the other end engages with the advance / retreat member. An optical element position control mechanism comprising a lever member, and the urging means further includes a lever urging member that urges the lever member in either the forward or reverse rotational direction with respect to the swing center. 5. The optical element position control mechanism according to claim 4, wherein the lever urging member has a coil portion supported by the support member with an axis line oriented in a direction orthogonal to the optical axis direction, and extends from the coil portion. A first arm portion engaged with the lever member; and a second arm portion extended from the coil portion and engaged with a spring hook portion of the support member. An optical element position control mechanism comprising a spring member that changes the amount of bending in the rotational direction around the coil portion. 5. The optical element position control mechanism according to claim 4, wherein one end of the lever urging member is engaged with the lever member and the other end is engaged with the support member. An optical element position control mechanism consisting of a telescopic spring that changes its length. 7. The optical element position control mechanism according to claim 6, wherein the length from the swing center of the lever member to the spring hooking portion of the expansion spring is longer than the length from the swing center to the engagement position with the advance / retreat member. Short optical element position control mechanism. 8. The optical element position control mechanism according to claim 1, further comprising a rotation frame that surrounds the optical axis and moves an optical element different from the optical element by rotation, and drives the advance / retreat member. The mechanism and the biasing means are optical element position control mechanisms provided radially outward from the rotary frame. 9. The optical element position control mechanism according to claim 8, wherein the rocking center of the biasing means and the engagement position with respect to the advancing / retracting member are located on the outside of the rotating frame and the rocking center of the rocking force applying part. An optical element position control mechanism arranged in one and the other of two regions which are substantially parallel to the axis and divided by a plane including the optical axis. 10. The optical element position control mechanism according to claim 1, wherein the advancing / retreating member driving mechanism includes a feed screw that rotates about an axis parallel to the optical axis direction, and a screw threaded on the feed screw. A nut that is advanced and retracted in the optical axis direction by forward and reverse rotation of the feed screw;
An optical element position control mechanism in which the advancing / retreating member has a moving position in the optical axis direction determined by contact with the nut, and the urging means urges the advancement / retraction member in the contact direction with the nut. 10. The optical element position control mechanism according to claim 1, wherein the drive mechanism of the advance / retreat member is provided with a guide member having a guide surface having an inclination component with respect to the optical axis direction, and protrudes from the advance / retreat member. And an optical element position control mechanism in which the follower is pressed against the guide surface by the urging force of the urging means.

Images