JP4159487B2 - Compressed storage structure for zoom lens barrel - Google Patents

Description

  The present invention relates to a compression housing structure for a zoom lens barrel.

  There is known a zoom lens system that has at least first, second, and third lens groups in order from the object side, and moves the first and third lens groups together during zooming. In a lens barrel equipped with this zoom lens system, in order to shorten the storage length, the first lens group is changed to the second lens group and the third lens group by releasing the integral movement relationship of the first and third lens groups during storage. Structures that move closer together are known. In general, a compression spring is inserted between the second lens group and the third lens group to urge them away from each other, and at the time of zooming (photographing area), at the separation end by this compression spring. The third lens group is retracted to create an integral movement relationship with the first lens group, and when stored, the compression spring is compressed to bring the third lens group closer to the second lens group (and the first lens group).

  In such a lens barrel, a linear guide mechanism is generally provided between a movable barrel that can move in the optical axis direction that supports the third lens group and another member that constitutes the lens barrel. However, if a large load is applied to the movable barrel, the linear guide relationship is canceled, and the movable barrel may fall off the lens barrel.

  As a measure for solving such a problem, it is conceivable to improve the strength of the rectilinear guide mechanism by making the rectilinear guide mechanism between the movable cylinder and the other member a complicated structure. It will be difficult to assemble the movable cylinder to the lens barrel.

  SUMMARY OF THE INVENTION An object of the present invention is to easily assemble a zoom lens barrel equipped with such a zoom lens system in which the first and third lens units are integrally moved, and reliably guide the first, second and third lens units in a straight line. An object of the present invention is to provide a compression storage structure that can be used.

The zoom lens barrel compression housing structure of the present invention includes at least first, second, and third lens groups in order from the object side, and moves the first and third lens groups together during zooming. A lens barrel for a zoom lens system that closes the first and third lens groups when housed, and a first group moving cylinder that supports the first lens group and is guided straight in the optical axis direction; second lens group A two-group moving cylinder that is guided in a straight line in the optical axis direction; a cam mechanism that moves the first group moving cylinder and the second group moving cylinder in the optical axis direction along an independent path; and a maximum separation position from the first group moving cylinder A third-group moving cylinder that supports the third lens group and is guided to move freely in the direction of the optical axis; and a spring that biases the third-group moving cylinder away from the first-group moving cylinder means; in the compression storage structure of the zoom lens barrel including a radial to the first group moving barrel Provided to protrude in the direction, a first linear guide projections heart hanging groove rear end faces the direction parallel to the optical axis is closed in the radially inner surface is formed; in the third lens group moving barrel A second rectilinear guide projection formed by projecting radially outward ; a rectilinear key formed on a front end portion of the second rectilinear guide projection and engaged with the suspension groove; a through groove in the second group moving cylinder The second rectilinear guide that is formed in parallel with the optical axis and that is slidably fitted from the radially outer side and the second rectilinear guide that is fitted slidably from the radially inner side. And a receding end of the third group moving cylinder with respect to the first group moving cylinder is restricted at a position where the rectilinear key contacts the rear end closing portion of the suspension groove. Features.

  Further, the suspension groove includes a narrow portion that communicates with the rectilinear guide groove, and a wide portion that communicates with the narrow portion and is wider in the circumferential direction than the narrow portion. It is preferable to include a neck portion that fits into the narrow portion and a head portion that is wider in the circumferential direction than the narrow portion and fits into the wide portion.

  The second group moving cylinder is provided with an introduction groove that communicates with the straight guide groove from a direction orthogonal to the straight guide groove. The first group moving cylinder has a specific groove with respect to the second group moving cylinder. An introduction groove that communicates with the introduction groove and the suspension groove is provided at a position in the optical axis direction, and the linearly-moving key of the third group moving cylinder is configured so that the introduction groove of the second group moving cylinder and the first group moving cylinder are assembled during assembly. It is practical to be fitted into the suspension groove through the introduction groove.

  According to the present invention, in a zoom lens barrel equipped with a zoom lens system in which the first and third lens units are integrally moved, it is easy to assemble, and the first, second, and third lens units can be guided in a straight line without fail. A structure is obtained.

  First, a zoom lens optical system to which the zoom lens barrel of the present embodiment is applied will be described with reference to FIG. The zoom lens system includes, in order from the object side, a first lens unit L1 having a positive power, a second lens unit L2 having a negative power, a third lens unit L3 having a positive power, and a fourth lens unit having a positive power. This is a varifocal lens system consisting of L4. The zooming is performed by the first to third lens units L1 to L3, and the focal point movement accompanying the zooming is corrected by the fourth lens unit L4. At the time of zooming, the first lens unit L1 and the third lens unit L3 move together at a constant interval. The fourth lens group L4 is a focus group at the same time. FIG. 1 depicts both a zooming trajectory and a trajectory during storage. Strictly speaking, the varifocus lens system is defined as a lens system in which focal movement is caused by zooming, and the zoom lens system is defined as a lens system in which focal movement does not occur. The system is treated as a kind of zoom lens system, and in the following description, the varifocal lens system is referred to as a zoom lens system.

  The overall structure of the zoom lens barrel of the present embodiment will be described with reference to FIGS. For example, as shown in FIG. 8, the fixed cylinder 11 fixed to the camera body is formed with a female helicoid 11a and a rectilinear guide groove 11b in a direction parallel to the optical axis. A male helicoid 12a formed at the rear end of the cam helicoid ring 12 is screwed into the female helicoid 11a of the fixed cylinder 11 as shown in FIG. A spur gear 12b is formed at the peak of the male helicoid 12a, and the spur gear 12b is positioned in the inner surface recess 11c (FIG. 3) of the fixed cylinder 11 and is rotatably supported (FIG. 15). Always see). Accordingly, when the cam helicoid ring 12 is rotated via the drive pinion 13 and the spur gear 12b, the cam helicoid ring 12 moves in the optical axis direction according to the male helicoid 12a and the female helicoid 11a. In the zoom lens barrel of this embodiment, the cam helicoid ring 12 is the only rotating member centered on the optical axis.

  A rectilinear guide ring 14 is fitted on the outer periphery of the cam helicoid ring 12. The rectilinear guide ring 14 has a radial rectilinear guide projection 14a on the outer surface of the rear end portion, and a bayonet projection 14b (FIG. 4) on the inner surface of the rear end portion. The rectilinear guide protrusion 14a is fitted in the rectilinear guide groove 11b of the fixed cylinder 11 so as to be relatively movable, and the bayonet protrusion 14b is a circumferential groove formed immediately before the male helicoid 12a (spur gear 12b) of the cam helicoid ring 12. It fits in 12c so as to be relatively rotatable. Therefore, the linear guide ring 14 moves together with the cam helicoid ring 12 in the optical axis direction without rotating.

  On the outer peripheral surface of the cam helicoid ring 12, as shown in FIGS. 4, 9, and 16, a cam groove C15 for the first group moving cylinder 15 that supports the first lens group L1 and a cam groove for the decorative cylinder 16 are provided. C16 is formed, and a cam groove C17 (see FIG. 19) for the second group moving cylinder 17 supporting the second lens group L2 is formed on the inner peripheral surface. The first group cam groove C15 and the decorative cylinder cam groove C16 are slightly different in shape and are formed in three circumferentially spaced apart, and the second group cam groove C17 has the same basic locus in the circumferential direction and the optical axis. Six are formed apart from each other in the direction. The first group moving cylinder 15, the decorative cylinder 16, and the second group moving cylinder 17 are each guided in a straight line in the optical axis direction, and follow the first group cam groove C15, the decorative cylinder cam groove C16, and the second group cam groove C17. As the cam helicoid ring 12 rotates, it advances and retreats in the optical axis direction.

  These straight-ahead guidance relationships will be described. As shown in FIGS. 4 and 5, the first group moving cylinder 15 has an outer cylinder 15X, an inner cylinder 15Y, and a flange wall 15Z connecting the outer cylinder 15X and the tip of the inner cylinder 15Y. The cam helicoid ring 12 is located between the outer cylinder 15X and the inner cylinder 15Y. A cam follower 15a that fits in the first group cam groove C15 of the cam helicoid ring 12 is fixed to the rear end portion of the outer cylinder 15X. As shown in FIGS. 8 and 9, a first group frame 24 to which the first lens group L1 is fixed is screwed and fixed to the distal end portion of the inner cylinder 15Y. The first group frame 24 can be used when zooming adjustment is performed by adjusting the position of the first lens group L1 in the optical axis direction.

  On the inner peripheral surface of the rectilinear guide ring 14 guided linearly by the fixed cylinder 11, rectilinear guide grooves 14c (FIG. 9) parallel to the optical axis are formed at intervals of approximately 120 °. A rectilinear guide protrusion 15b protruding in the radial direction from the rear end portion of the outer cylinder 15X is fitted. The outer cylinder 15X of the first group moving cylinder 15 is formed with a narrow rectilinear guide groove 15d (FIG. 16) at the rear end of the assembly groove 15c. The rectilinear guide groove 15d is linearly moved with the outer cylinder 15X. A rectilinear guide key 16a fixed to the decorative cylinder 16 located between the guide rings 14 is located. The relative movement distance of the first group moving cylinder 15 and the decorative cylinder 16 in the optical axis direction (the difference in shape between the first group cam groove C15 and the decorative cylinder cam groove C16) is slight, and the optical axis direction of the rectilinear guide groove 15d is small. The length of is correspondingly short. The linear guide key 16a is integrally provided with a cam follower 16b that fits into the decorative cylinder cam groove C16.

  A compression coil spring 19 (see FIGS. 3 to 5) is inserted between the first group moving cylinder 15 and the decorative cylinder 16. The compression coil spring 19 moves and energizes the first group moving cylinder 15 backward and the decorative cylinder 16 forward, and between the first group cam groove C15 and the cam follower 15a and between the decorative cylinder cam groove C16 and the cam follower 16b. It works to take backlash between.

  Further, as shown in FIG. 16, the first group cam groove C15 and the decorative cylinder cam groove C16 extend the decorative cylinder 16 forward relative to the first group movable cylinder 15 in the storage position compared to the photographing position. The shape is set to be slightly different so as to prevent interference between the barrier of the barrier block 30 (FIG. 8) and the first lens unit L1. More specifically, as shown in FIG. 16, the optical axis direction distance Q between the first group cam groove C15 and the decorative tube cam groove C16 is greater in the preparation section (section from the storage position until the barrier is fully opened). The shapes of the first group cam groove C15 and the decorative tube cam groove C16 are set to be larger than the zoom section (section from the wide end position to the tele end position). That is, in the preparatory section, Q = Q1 in all sections, but the distance Q gradually decreases from the position OP2 (that is, from the position where the lens L1 and the barrier do not interfere) after passing through the barrier fully open position OP1 by a predetermined amount. In the wide end position, Q = Q2 (<Q1). In the zoom section, Q = Q2 in all the sections. In the storage position shown in FIG. 3, the clearance c1 between the flange wall 15Z at the front end of the first group moving cylinder 15 and the flange wall of the decorative cylinder 16 positioned in front of the flange wall 15Z is the shooting state shown in FIG. It can be seen that the clearance is larger than the clearance between both flange walls. In other words, vignetting by the barrier block 30 is prevented by bringing the barrier block 30 closer to the first lens unit L1 at the photographing position. The barrier block 30 is supported by the front end of the decorative cylinder 16, and the barrier opening / closing ring 31 (FIG. 9) positioned immediately behind the barrier block 30 is rotated by the cam helicoid ring 12 in the vicinity of the storage position. Open and close the barrier. A barrier mechanism that opens and closes the barrier block 30 by the rotational movement of the barrier opening and closing ring 31 is well known. In the present embodiment, the shapes of the first group cam groove C15 and the decorative cylinder cam groove C16 are set so that the distance Q becomes a constant value (= Q2) in the zoom section, but depending on the focal length. The distance Q may be changed, and the distance Q in the zoom section may be larger than the distance Q in the preparation section.

  The front end of the decorative cylinder cam groove C16 is opened, and the cam follower 16b of the decorative cylinder 16 is inserted into the cam groove C16 from the open end C16a (FIG. 16) at a specific assembly position. The Similarly, for the first group cam groove C15, the cam follower 15a of the first group moving cylinder 15 is inserted from the front end open end C15a.

  The inner cylinder 15Y of the first group moving cylinder 15 is formed with a rectilinear guide protrusion 15f (FIGS. 6 and 7) in a direction parallel to the optical axis on the inner peripheral surface. A rectilinear guide groove 17a is formed in a direction parallel to the optical axis into which the rectilinear guide protrusion 15f is slidably fitted. A suspension groove 15e is formed at the center of the straight guide protrusion 15f in a direction parallel to the optical axis, and the rear end of the suspension groove 15e is closed (see FIGS. 17 and 18). The second group moving cylinder 17 is formed with a cam follower 17c that fits into the second group cam groove C17 of the cam helicoid ring 12.

  On the inner periphery of the second group moving cylinder 17, the third group moving cylinder 18 supporting the third lens group L3 is located. The third group moving cylinder 18 is formed with a rectilinear guide protrusion 18a that is parallel to the optical axis and is fitted in the rectilinear guide groove 17a of the second group moving cylinder 17 so as to be relatively slidable from the inside. A rectilinear key 18b (FIGS. 11, 17, and 18) that fits in the hanging groove 15e is formed at the center of the rectilinear guide protrusion 18a. As shown in FIG. 11, a shutter block 20 is inserted into the third group moving cylinder 18 in front of the third lens group L3, and is fixed by a holding ring 20a. A compression coil spring 21 is inserted between the third group moving cylinder 18 (restraining ring 20 a) and the second group moving cylinder 17, and the third group moving cylinder 18 is always in relation to the second group moving cylinder 17. Is urged to move backward. The rearward movement end of the third group moving cylinder 18 is restricted at a position where the linear key 18b contacts the rear end of the suspension groove 15e of the first group moving cylinder 15. In other words, in the shooting state, the state where the straight key 18b is in contact with the rear end portion of the suspension groove 15e of the first group moving cylinder 15 is maintained, and the relative distance between the first lens group L1 and the third lens group L3 is constant. It becomes. When the zoom lens barrel changes from the photographing state to the retracted state, after the third lens unit L3 (third group moving barrel 18) reaches the mechanical retracted end, the first lens unit L1 moves to the first group cam. When further retracting according to the groove C15, the compression coil spring 21 is bent and the first lens unit L1 approaches the third lens unit L3 (see FIG. 1). The straight key 18b has a swelled head and is prevented from falling off the hanging groove 15e.

  The compression coil spring 21 may be directly applied to the second group moving cylinder 17 (the second lens group L2 may be fixed to the second group moving cylinder 17), but in the illustrated embodiment, the storage length is further reduced. Therefore, the second lens unit L2 can be retracted with respect to the second group moving cylinder 17. FIG. 12 and FIG. 13 show the configuration. The second group moving cylinder 17 is formed with a cylindrical portion 17e having an inward flange 17d at the tip, and this cylindrical portion 17e has an optical axis and Three rectilinear guide grooves 17f that are parallel and open at the rear end and the front end are formed at equiangular intervals in the circumferential direction. The cylindrical portion 17e is fitted with a flange portion 25a formed on the intermediate cylindrical member 25, and three radially outward guide projections 25d are provided on the outer peripheral surface of the flange portion 25a so as to protrude at equal angular intervals in the circumferential direction. Are fitted into the corresponding straight guide grooves 17f from the rear. For this reason, the intermediate cylinder member 25 is restricted in relative rotation around the optical axis with respect to the second group moving cylinder 17, and can be relatively moved only in the optical axis direction. It can move forward until it comes into contact. The second lens group L2 is fixed to the second group frame 26, and the male screw 26b of the second group frame 26 is screwed into a female screw 25e formed on the inner periphery of the intermediate cylinder member 25. Therefore, by rotating the second group frame 26 relative to the intermediate cylinder member 25 whose rotation about the optical axis is restricted, the position of the second lens group L2 in the optical axis direction can be adjusted (zooming adjustment). After the adjustment, the second group frame 26 can be fixed to the intermediate cylinder member 25 by dropping the adhesive from the adhesive hole 25b. Between the front end face of the inner flange 17d of the second group moving cylinder 17 and the outer flange 26a of the second group frame 26, there is a gap c2 (FIG. 13) including the adjustment allowance. The compression coil spring 21 acts on the intermediate cylinder member 25, and normally, the intermediate cylinder member 25 is held at a position where the flange portion 25a abuts against the inner flange 17d. That is, the position of the second lens group L2 is controlled by the second group cam groove C17 in the shooting state, while the second group frame 26 is mechanically pushed backward by the rear end of the first group frame 24 during storage. The outer flange 26a can be retracted to a position where it abuts against the inner flange 17d, and the storage length can be shortened by the gap c2.

  A light shielding frame 27 is supported on the intermediate cylinder member 25. The light-shielding frame 27 includes an annular light-shielding portion 27a, a holding leg 27b extending forward from the annular light-shielding portion 27a at an interval of approximately 120 °, and a retaining hook portion 27c that is bent outward at the tip end portion of the holding leg 27b. The intermediate cylinder member 25 is formed with a light shielding member holding hole 25c into which the retaining hook portion 27c is fitted (FIG. 12). A conical coil spring 28 is inserted between the light shielding frame 27 and the second group frame 26, and always urges the light shielding frame 27 to move backward. When the light shielding frame 27 reaches the mechanical retracted end when the lens barrel is housed, the light shielding frame 27 bends the conical coil spring 28 and approaches the second group frame 26. The length of the light shielding member holding hole 25c in the optical axis direction is set so that the annular light shielding portion 27a can come into contact with the second lens unit L2.

  The conical coil spring 28 further functions to remove backlash during zooming adjustment performed by rotating the second group frame 26. The zooming adjustment is an adjustment performed by adjusting the position of the second lens unit L2 in the optical axis direction while observing the image position, and backlash with respect to the intermediate cylinder member 25 (second group moving cylinder 17) of the second group frame 26 is performed. By removing, accurate adjustment can be made.

  The fourth lens group L4 is fixed to the fourth group frame 22. As described above, the fourth lens group L4 has a role of correcting the focal movement of the varifocal lens system and a role of the focus lens group, and is advanced and retracted by the pulse motor 23. That is, the drive shaft of the pulse motor 23 is a screw shaft 23a, and a nut member 23b whose rotation is restricted is screwed onto the screw shaft 23a. The nut member 23b is constantly urged to move in a direction in which the nut member 23b comes into contact with the foot portion 22a of the fourth group frame 22 by the spring means S, and the rotation of the fourth group frame 22 is restricted by the guide bar 22b. Therefore, when the pulse motor 23 is driven, the fourth group frame 22 (fourth lens group L4) moves forward and backward in the optical axis direction. The pulse motor 23 is controlled according to focal length information and subject distance information.

  Therefore, in the zoom lens barrel having the above-described configuration, when the cam helicoid ring 12 is rotated via the drive pinion 13, the first group moving cylinder 15, the decorative cylinder 16, and the second group moving cylinder 17 which are guided in a straight line are cam grooves. It moves in the optical axis direction according to C15, C16, C17. The third group moving cylinder 18 moves together with the first group moving frame 15 when the first group moving cylinder 15 moves forward from the storage position and the rectilinear key 18b contacts the rear end of the suspension groove 15e. The position of the fourth lens unit L4 is controlled by a pulse motor 23 that is controlled according to the focal length information, and the focal movement of the varifocal lens system is corrected. As a result, a zooming locus as shown in FIG. 1 is obtained. The pulse motor 23 is also controlled by subject distance information, and a focusing operation is executed.

As described above, in this embodiment, the first lens unit L1, the second lens unit L2, the third lens unit L3, and the fourth lens unit L4 are provided in this order from the object side, and zooming is performed from the first lens unit L1. The third lens unit L3 is used. At this time, the first lens unit L1 and the third lens unit L3 are moved together. Then, the first lens group L1 is supported, the cam follower 15a of the first group moving cylinder 15 positioned outside the cam helicoid ring 12 is engaged with the cam groove C15 of the cam helicoid ring 12, and the second lens group L2 is moved. The cam follower 17c of the second group moving cylinder 17 that is supported and located inside the cam helicoid ring 12 is engaged with the cam groove C17 of the cam helicoid ring 12.
The cam follower 15a of the first group moving cylinder 15 and the cam groove C15 of the cam helicoid ring 12 are components of a cam mechanism for moving the first group moving cylinder 15 in the optical axis direction, and the cam follower 17c of the second group moving cylinder 17 and The cam groove C17 of the cam helicoid ring 12 is a component of a cam mechanism for moving the second group moving cylinder 17 in the optical axis direction.

The first group moving cylinder 15 is moved straight by fitting the straight guide protrusion 15b of the outer cylinder 15X of the first group moving cylinder 15 into the straight guide groove 14c of the straight guide ring 14 guided by the fixed cylinder 11. I am guiding you.
Further, the second group moving cylinder 17 is guided in a straight line by fitting the rectilinear guide protrusion (first rectilinear guide protrusion) 15 f of the inner cylinder 15 Y of the first group moving cylinder 15 into the rectilinear guide groove 17 a of the second group moving cylinder 17. ing.

Further, the third group moving cylinder 18 is guided in a straight line by the second group moving cylinder 17 by fitting the straight guide protrusion 18 a into the straight guide groove 17 a. Further, a straight advance key (stopper protrusion) 18b provided at the front end portion of the straight advance guide protrusion (second straight advance guide protrusion) 18a is fitted into a suspension groove 15e formed in the straight advance guide protrusion 15f, whereby the third group. The moving cylinder 18 is guided straight by the first group moving cylinder 15. That is, the rectilinear guide protrusion 15f of the inner cylinder 15Y guides the second movable cylinder 17 through the rectilinear guide groove 17a by both edges thereof, and the three groups by the substantially central portion (that is, the suspension groove 15e). The structure is such that the movable cylinder 18 is guided in a straight line, and the linear guide structure of the two movable cylinders can be miniaturized by effectively utilizing the three surfaces of the protruding portion. Further, the rectilinear guide groove 17a has a structure that is fitted over both edges of the rectilinear guide protrusion 15f and the rectilinear guide protrusion 18a, and the radial protrusion dimensions of the rectilinear guide protrusion 15f and the rectilinear guide protrusion 18a are two groups. It is absorbed by the thickness of the moving cylinder 17. Therefore, it is possible to increase the strength of the zoom lens barrel without increasing the radial thickness of the lens barrel and to perform reliable straight guidance. Furthermore, since the outer cylinder 15X of the first group moving cylinder 15 is guided straight by the straight guide ring 14, and the second group moving cylinder 17 and the third group moving cylinder 18 are guided straight by the inner cylinder 15Y of the first group moving cylinder 15, The diameter of the zoom lens barrel is reduced as compared with the prior art. In this way, since the third group moving cylinder 18 is guided straight by the two members of the second group moving cylinder 17 and the first group moving cylinder 15, a large load is applied to the second group moving cylinder 17 or the first group moving cylinder 15. In addition, the third group moving cylinder 18 can be guided in a straight line in a stable state, and even if a large load is applied to the third group moving cylinder 18, the third group moving cylinder 18 is less likely to fall out of the zoom lens barrel.
Moreover, as shown in FIG. 6, the suspending groove 15e includes a narrow width portion 15e1 and a wide width portion 15e2 whose circumferential width is wider than the narrow width portion 15e1, and the rectilinear key 18b is formed in the narrow width portion 15e1. A neck portion 18b1 to be fitted and a head portion 18b2 formed at the tip portion of the neck portion 18b1 and having a circumferential width that swells wider than the narrow width portion 15e1. The head portion 18b2 is fitted to the wide portion 15e2, and not only prevents the neck portion 18b1 from coming off from the narrow portion 15e1, but is also guided straight by the wide portion 15e2, so the third group moving cylinder 18 Stable linear guidance is provided through the first group moving cylinder 15.

  The rear end portion of the suspending groove 15e is closed, and the separation distance between the first group moving cylinder 15 and the third group moving cylinder 18 when the rectilinear key 18b comes into contact with the rear end portion (rear end closing portion) of the suspending groove 15e. Is the maximum. Further, a second group moving cylinder 17 (first group moving cylinder 15) and a third group moving cylinder 18 are provided between the intermediate cylinder member 25 whose forward end is restricted with respect to the second group moving cylinder 17 and the third group moving cylinder 18. A compression coil spring (spring means) 21 that urges in a direction away is contracted.

  Further, in the present embodiment, as described above, the third group moving cylinder 18 is linearly guided by the first group moving cylinder 15 and the second group moving cylinder 17, and the suspension groove 15e and the straight key 18b are formed in a special shape. An assembly structure that facilitates assembly is provided.

  As shown in FIGS. 17 to 19, the second group moving cylinder 17 is provided with an introduction notch groove 17a1 perpendicular to the rectilinear guide groove 17a and communicating with the rectilinear guide groove 17a, and this introduction notch groove 17a1. And a bottomed introduction groove 17a2 formed to the rear end of the second group moving cylinder 17 in a direction parallel to the optical axis. Furthermore, the inner cylinder 15Y of the first group moving cylinder 15 is formed with a bottomed introduction groove 15a1 which is orthogonal to the suspension groove 15e and penetrates the wall of the rectilinear guide projection 15f from one direction and communicates with the suspension groove 15e. ing. The circumferential lengths of these introduction grooves 15a1 and 17a1 are set to be longer than the circumferential length of the head 18b2 of the rectilinear key 18b.

  In order to assemble the third group moving cylinder 18 to the zoom lens barrel, first, the cam helicoid ring 12 is rotated to adjust the positions of the first group moving cylinder 15 and the second group moving cylinder 17 in the optical axis direction, and the introduction groove 15a1. The position of the introduction notch groove 17a1 in the optical axis direction is matched, and an L-shaped introduction path is formed by the three grooves of the introduction groove 15a1, the introduction notch groove 17a1, and the bottomed introduction groove 17a2. Next, the third group moving cylinder 18 is moved from the rear of the second group moving cylinder 17 into the second group moving cylinder 17 in a state where the head 18b2 of each straight key 18b is aligned with the rear end (open end) of the corresponding bottomed introduction groove 17a2. And the head portion 18b2 of each straight key 18b is positioned in the bottomed introduction groove 17a2. When the third group moving cylinder 18 is further inserted into the second group moving cylinder 17, the head portion 18b2 of each rectilinear key 18 reaches the connecting portion between the bottomed introduction groove 17a2 and the introduction notch groove 17a1. When the third group moving cylinder 18 is rotated in a predetermined direction around the optical axis with respect to the second group moving cylinder 17 from this state, the rectilinear key 18b rotates in the circumferential direction through the introduction notch groove 17a1 and the introduction groove 15a1. As a result, the neck portion 18b1 and the head portion 18b2 of the rectilinear key 18b are fitted into the narrow portion 15e1 and the wide portion 15e2 of the suspension groove 15e, respectively. When the cam helicoid ring 12 is rotated in this state to shift the positions of the introduction groove 15a1 and the introduction notch groove 17a1 in the optical axis direction, the linear key 18 becomes non-rotatable in the circumferential direction, and the assembly of the third group moving cylinder 18 is completed. . Note that, in the photographing region and the storage position, the positions of the introduction groove 15a1 and the introduction notch groove 17a1 in the optical axis direction are shifted, so that the rectilinear key 18 moves to the introduction groove 15a1 and the introduction notch groove 17a1 side, so It will not fall out of the zoom lens barrel.

The zoom lens barrel described with reference to FIGS. 1 to 19 is an example to which the compression housing structure of the present invention is applied, and has a cam ring and a lens support cylinder regardless of whether the cam ring is a helicoid cam ring. It is obvious that the zoom lens barrel can be applied in general.

It is a figure which shows the zooming basic locus | trajectory of the zoom lens system to which the zoom lens barrel by this invention is applied. FIG. 2 is a half-cut perspective view showing a lens group and its lens frame of the zoom lens system. It is an upper half sectional view in the storage state of the zoom lens barrel according to an embodiment of the present invention. It is an upper half sectional view in the wide end infinity photographing state of the zoom lens barrel. It is a lower half sectional view in the tele end infinity photographing state of the zoom lens barrel. It is sectional drawing which follows the VI-VI line of FIG. It is sectional drawing which follows the VII-VII line of FIG. It is a disassembled perspective view of a part of the zoom lens barrel. It is a disassembled perspective view of the another part. It is a disassembled perspective view around the first group moving cylinder. It is a disassembled perspective view around the third group moving cylinder. It is a disassembled perspective view around the second group moving cylinder. It is an upper half sectional view around the second group moving cylinder. It is the disassembled perspective view seen from the back surface around the pulse motor supported by a fixed cylinder. FIG. 6 is an exploded perspective view around the fixed cylinder and a fourth lens group. It is an expanded view of the cam groove for 1 group of a cam helicoid cylinder, and the cam groove for a decoration cylinder. It is an expanded view which shows the rectilinear guide relationship of the 1st group moving cylinder, 2nd group moving cylinder, and 3rd group moving cylinder. FIG. It is an expanded view which shows the shape of the cam groove for 2 groups of a cam helicoid ring.

Explanation of symbols

C15 Group 1 cam groove (cam mechanism)
C16 Decorative cylinder cam groove C17 Group 2 cam groove (cam mechanism)
L1 1st lens group L2 2nd lens group L3 3rd lens group L4 4th lens group S Spring means 11 Fixed cylinder 11a Female helicoid 11b Straight guide groove 11c Inner surface recess 12 Cam helicoid ring 12a Male helicoid 12a1 Mountain 12a2 Valley 12b Spur gear 12b1 Valley 12c Circumferential groove 12d Straight guide groove 12e Gear helicoid protrusion 12f Rear extension 12f1 Inclined boundary surface 12f2 Axial boundary surface 12f3 Circumferential boundary surface 12g Gear helicoid protrusion 12g1 Notch 12g2 Inclined boundary surface 12g3 Axial boundary surface 12g4 Circumferential direction Boundary surface 12g5 Projection 13 Drive pinion 14 Linear guide ring 14a Linear guide projection 14b Bayonet projection 14c Linear guide groove 15 Group 1 moving cylinder 15a Cam follower (cam mechanism)
15b rectilinear guide protrusion 15c assembly groove 15d rectilinear guide groove 15e suspension groove 15e1 narrow portion 15e2 wide portion 15f rectilinear guide projection (first rectilinear guide projection)
15X outer cylinder 15Y inner cylinder 15Z flange wall 16 decorative cylinder 16a rectilinear guide key 16b cam follower 17 second group moving cylinder 17a rectilinear guide groove 17c cam follower (cam mechanism)
17d Inner flange 17e Cylindrical portion 17f Straight guide groove 18 Third group moving cylinder 18a Straight guide protrusion (second straight guide protrusion)
18b Straight key 18b1 Neck 18b2 Head 19 Compression coil spring 20 Shutter block 20a Retaining ring 21 Compression coil spring (spring means)
22 4th group frame 22a Foot 22b Guide bar 23 Pulse motor 23a Screw shaft 23b Nut member 24 1st group frame 25 Intermediate cylinder member 25a Flange part 25b Adhesive hole 25c Shading member holding hole 25d Guide projection 25e Female screw 26 2nd group frame 26a Outside Side flange 26b Male screw 27 Shading frame 27a Annular shading portion 27b Holding leg 27c Retaining hook portion 28 Conical coil spring 30 Barrier block 31 Barrier opening / closing ring

Claims (3)

In order from the object side, it has at least first, second, and third lens groups. When zooming, the first and third lens groups are moved together, and when retracted, the first and third lens groups are moved closer. A lens barrel for a zoom lens system,
A first-group moving cylinder that supports the first lens group and is guided straight in the optical axis direction;
A two-group moving cylinder that supports the second lens group and is guided straight in the optical axis direction;
A cam mechanism for moving the first group moving cylinder and the second group moving cylinder in the optical axis direction along independent paths;
A third-group moving cylinder supporting a third lens group, which is guided in a straight line in the direction of the optical axis and restricts the maximum separation position from the first-group moving cylinder; and the third-group moving cylinder is the first-group moving cylinder Spring means for moving and biasing in a direction away from
In the compression storage structure of the zoom lens barrel with
A first straight traveling in which a suspension groove with a rear end portion closed is formed at the center of the radially inner side surface, facing the direction parallel to the optical axis , provided to project radially inward from the first group moving cylinder. Guide protrusion;
A second rectilinear guide protrusion formed by projecting radially outward in the third group moving cylinder;
A rectilinear key that is formed at the front end of the second rectilinear guide projection and engages with the suspension groove;
The first straight guide protrusion, which is formed as a through groove in the second group moving cylinder, is parallel to the optical axis and is slidable from the radially outer side, and is slidably fitted from the radially inner side. A rectilinear guide groove extending over the second rectilinear guide protrusion to be joined;
Have
A zoom lens barrel compression storage structure, wherein a retracting end of the third group moving cylinder with respect to the first group moving cylinder is regulated at a position where the linear key abuts a rear end closing portion of the suspension groove. In the compression housing structure of the zoom lens barrel according to claim 1,
The suspension groove includes a narrow portion that communicates with the rectilinear guide groove, and a wide portion that communicates with the narrow portion and is wider in the circumferential direction than the narrow portion. A compression housing structure for a zoom lens barrel, comprising: a neck portion that fits into a narrow width portion; and a head portion that is wider in the circumferential direction than the narrow width portion and fits into the wide width portion. The zoom lens barrel compression housing structure according to claim 1 or 2, wherein the second group moving cylinder is provided with an introduction groove as a through groove communicating with the straight guide groove from a direction orthogonal to the straight guide groove. The first group moving cylinder is provided with an introduction groove communicating with the introduction groove and the suspension groove at a specific position in the optical axis direction with respect to the second group moving cylinder. A compression housing structure for a zoom lens barrel that is fitted into the suspension groove through the introduction groove of the second group moving cylinder and the introduction groove of the first group moving cylinder during assembly.

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