JP5201811B2 - Lens barrel and imaging device - Google Patents

Description

  The present invention relates to a lens barrel having an extension cam mechanism and an imaging apparatus.

  Conventionally, various techniques have been proposed as a feeding cam mechanism for a zoom lens barrel mounted on an imaging apparatus (see, for example, Patent Document 1).

  FIG. 11 is a perspective view showing a configuration of a movable ring of a zoom lens barrel according to a conventional example. FIG. 12 is a development view of the inner peripheral surface of the cam ring of the zoom lens barrel according to the conventional example.

  11 and 12, a movable ring 201 is a member that supports a part of the photographing optical system of the imaging apparatus, and includes a plurality of cam followers 201a and 201b that engage with cam grooves of the cam ring 101 described below. . The cam ring 101 includes a plurality of cam grooves 101a and 101b having the same basic locus α. The cam ring 101 is open to the cam ring end surface in a state where none of the front grooves or rear parts of the plurality of cam grooves 101a and 101b exists (cuts in the middle).

  The cam followers 201a and 201b of the movable ring 201 are engaged with the cam grooves 101a and 101b of the cam ring 101, and the cam ring 101 rotates about the optical axis, thereby moving the movable ring 201 back and forth in the optical axis direction. ing. The cam follower 201a is detached from the cam groove 101a of the cam ring 101 at the front moving end of the movable ring 201, and the cam follower 201b is detached from the cam groove 101b of the cam ring 101 at the rear moving end of the movable ring 201. Even if one cam follower is disengaged from the cam groove, the other cam follower and the cam groove maintain engagement so that they do not deviate from the basic locus α.

  With the above-described configuration, it is possible to ensure the necessary amount of movement of the movable ring 201 without increasing the length of the cam ring 101 in the optical axis direction.

  In FIG. 13, three cam grooves 301 a are formed on the inner peripheral surface of the cam ring 301. On the outer periphery of the movable ring 302, there are two fixed cam followers 302a that engage with the cam groove 301a of the cam ring 301, and a movable follower 303 that is biased by the biasing spring 304 to the cam groove 301a of the cam ring 301. It is arranged.

As can be seen from FIG. 13, when the movable follower 303 is urged by the cam groove 301a of the cam ring 301, the remaining two fixed cam followers 302a of the movable ring 302 are also in contact with the cam groove 301a. Become. Therefore, it becomes possible to absorb the backlash of parts at the cam follower of the movable ring 302 and the cam groove of the cam ring 301, and even if the movable ring 302 is advanced and retracted in the optical axis direction during zooming operation, the center of the optical axis is always stable. Can be guaranteed.
JP 2004-085932 A

  However, in the conventional example shown in FIGS. 11 and 12, it is impossible to adopt the general configuration shown in FIG. The reason is that the cam follower of the movable ring comes off from the cam groove of the cam ring. When the movable follower is provided on the movable ring, the movable follower that has come out of the cam groove comes into contact with the cam groove when the movable ring is restored, and the operation of the movable ring becomes unstable.

  Therefore, the conventional example (FIG. 11) has a configuration in which three fixed cam followers are provided on the movable ring. However, it is impossible to eliminate the gap between the cam follower of the movable ring and the cam groove of the cam ring, and it is difficult to guarantee the center of the optical axis of the movable ring during zooming operation of the zoom lens barrel. was there. Further, if the accuracy of the parts is increased in order to reduce the gap between the cam follower of the movable ring and the cam groove of the cam ring as much as possible, there is a problem that the manufacturing cost increases.

  An object of the present invention is to provide a lens barrel and an imaging apparatus that can guarantee the center of the optical axis of a photographing barrel member without depending on component accuracy.

In order to achieve the above object, a lens barrel of the present invention is a lens barrel that holds a photographing optical system, wherein a plurality of first cam followers are disposed on an outer peripheral surface, and a part of the photographing optical system is provided. A cylindrical photographing lens barrel member to be held, a plurality of second cam followers disposed on the outer peripheral surface, a movable member movable in the optical axis direction relative to the photographing lens barrel member, and the plurality of the plurality of second cam followers A plurality of first cam grooves that engage with the first cam follower and a plurality of second cam grooves that engage with the plurality of second cam followers are disposed on the inner peripheral surface, and the photographing lens barrel is rotated with rotation. A cylindrical cam member that moves the member and the moving member back and forth in the optical axis direction of the imaging optical system, and the first camcorder is biased in a direction in which the imaging barrel member and the moving member are separated in the optical axis direction. a first biasing member for biasing the cam follower to said first cam groove, before And said moving member and the taking lens barrel member is biased in a direction perpendicular to the optical axis direction and a second urging member for urging said second cam follower on said second cam groove, the A part of the first cam groove is formed with a non-engagement area in which the plurality of first cam followers are disengaged when the imaging barrel member advances and retreats in the optical axis direction. When the first cam follower and the second cam follower are engaged with the first cam groove and the second cam groove, respectively, the first biasing force is greater than the biasing force of the second biasing member. The biasing force of the biasing member is strong.

  According to the present invention, the cam follower of the photographic lens barrel member falls out of the cam groove of the cam member in a part of the normal region in the optical axis direction and is in the disengaged state.

  In addition, a moving member is interposed between the imaging barrel member and the cam member, and each of these members can absorb backlash of parts. As a result, it is possible to secure a necessary amount of movement of the photographing barrel member without increasing the length of the cam member in the optical axis direction, and further, the optical axis center of the photographing barrel member depends on the component accuracy. It can be guaranteed without any problems.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a configuration (collapse position) of a zoom lens barrel as a lens barrel according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing the configuration of the zoom lens barrel (WIDE ANGLE (hereinafter referred to as WIDE) position). FIG. 3 is a cross-sectional view showing the configuration of the zoom lens barrel (TELESCOPE (hereinafter TELE) position).

  1 to 3, first, the overall configuration of the zoom lens barrel will be described. The zoom lens barrel includes a first group lens 1, a second group lens 2, a third group lens 3, a first group lens barrel 11, a second group lens barrel 12, and a third group lens barrel 13. The zoom lens barrel further includes a moving follower base plate 14, an aperture shutter unit 15, a moving cam ring 21, a fixed cylinder 22, a CCD holder 23, and a straight guide ring 24.

  The first group lens 1 and the second group lens 2 are lenses having a zooming action. The third group lens 3 is a lens that controls focus (focus adjustment) and image plane correction. The CCD 4 is an image sensor that photoelectrically converts an optical image of a subject formed through the first group lens 1, the second group lens 2, and the third group lens 3 into an electrical signal. The first group lens barrel 11, the second group lens barrel 12, and the third group lens barrel 13 are respectively cylindrical (annular) that hold the first group lens 1, the second group lens 2, and the third group lens 3 so as to be movable in the optical axis direction. It is a member. The first group barrel 11, the second group barrel 12 and the movable follower base plate 14 are held by a movable cam ring 21 having a cam groove (described later) on the inner peripheral surface.

  The moving follower base plate 14 is a cylindrical (annular) member that is guided linearly in the optical axis direction relative to the second group barrel 12. The aperture shutter unit 15 is a known mechanism that performs an aperture operation and a shutter operation. The aperture shutter unit 15 is fixed to the second group barrel 12 and is moved integrally with the second group barrel 12 in the optical axis direction. The movable cam ring 21 includes three follower pins 21a disposed on the outer peripheral surface, a groove portion 21b disposed on the inner peripheral surface, and cam grooves 21c, 21d, and 21e disposed on the inner peripheral surface. It is arranged on the inner peripheral side of the tube 22.

  The fixed cylinder 22 includes a cam groove 22a disposed on the inner peripheral surface, and holds the movable cam ring 21 movably in the optical axis direction via the cam groove 22a. The CCD holder 23 holds the rear end of the fixed cylinder 22 in the optical axis direction and holds the CCD 4 and a low-pass filter (not shown). The rectilinear guide ring 24 includes a front projection 24a disposed on the outer peripheral portion of the front end portion in the optical axis direction, and a flange portion 24b disposed on the rear end portion in the optical axis direction. The first and second group lens barrels 12 are restrained from rotating and moved straight in the optical axis direction.

  Next, the operation of the zoom lens barrel configured as described above will be described in detail.

  As a result of the rotation of the zoom motor mounted on the zoom lens barrel being transmitted via a gear (not shown) on the outer periphery of the moving cam ring 21 meshing with a gear disposed on the zoom motor output side, the movement The cam ring 21 rotates. Here, the three follower pins 21 a disposed on the outer peripheral surface of the movable cam ring 21 are respectively fitted with the three cam grooves 22 a disposed on the inner peripheral surface of the fixed cylinder 22. Accordingly, the moving cam ring 21 moves in the optical axis direction while rotating along the cam groove 22 a of the fixed cylinder 22.

  A front protrusion 24 a disposed on the outer peripheral portion of the front end portion of the rectilinear guide ring 24 is in contact with a groove portion 21 b disposed on the inner peripheral surface of the movable cam ring 21. Further, the flange portion 24 b disposed at the rear end portion of the rectilinear guide ring 24 is in contact with the rear end portion of the movable cam ring 21. As a result, the linear guide ring 24 is restricted from moving relative to the movable cam ring 21 in the optical axis direction.

  Further, the rectilinear guide ring 24 is fitted to a rectilinear guide (not shown) disposed on the inner peripheral side surface of the fixed cylinder 22 so as to be able to advance straight. Thereby, the linear guide ring 24 is restricted from moving in the rotational direction. Accordingly, when the movable cam ring 21 moves in the optical axis direction while rotating along the cam groove 22a of the fixed cylinder 22, the rectilinear guide ring 24 follows the movement of the movable cam ring 21 in the optical axis direction to follow the optical axis. Move only in the direction.

  Cam grooves 21c, 21d, and 21e disposed on the inner peripheral surface of the movable cam ring 21 are respectively provided with a cam follower 11a of the first group barrel 11, a cam follower 12a of the second group barrel 12, and a cam follower 14a of the movable follower base plate 14. Are mated. A rectilinear guide groove (not shown) having a constant width is disposed on the side surface of the rectilinear guide ring 24 in parallel with the optical axis. The first group lens barrel 11, the second group lens barrel 12, and the third group lens barrel 13 are restrained from rotating by the rectilinear guide groove of the rectilinear guide ring 24.

  Therefore, when the movable cam ring 21 moves, the first group barrel 11, the second group barrel 12, and the third group barrel 13 do not rotate, and the cam grooves 21c, 21d, and 21e on the inner peripheral surface of the movable cam ring 21 are rotated. Along the optical axis. Thereby, it is possible to arrange lenses according to a desired focal length in the zoom lens barrel.

  Next, the configuration of the second group barrel 12 in the zoom lens barrel will be described in detail.

  FIG. 4 is an exploded perspective view showing the configuration of the second group barrel 12, the movable follower base plate 14, and the compression spring 33. FIG. 5 is a perspective view showing a state in which the second group barrel 12, the movable follower base plate 14, and the compression spring 33 are assembled. FIG. 6 is a front view of the second group barrel 12. 7 is a cross-sectional view of the second group barrel 12 taken along the line AA in FIG.

  4 to 7, three rectilinear guide grooves 14b having a uniform width in the optical axis direction are arranged on the inner peripheral side surface of the movable follower base plate 14 at predetermined intervals in the circumferential direction. In addition, three rectilinear keys 12b are arranged on the outer peripheral surface of the second group barrel 12 at predetermined intervals in the circumferential direction. The three rectilinear guide grooves 14b of the movable follower base plate 14 are respectively fitted to the three rectilinear keys 12b of the second group barrel 12. Thereby, the rotational follower base plate 14 is restricted from rotating relative to the second group barrel 12 and moves only in the optical axis direction relative to the second group barrel 12.

  A movable pin 31 and an urging spring 32 are incorporated in a hole 12c provided in one of the three rectilinear keys 12b of the second group barrel 12 (see FIG. 7). The second group barrel 12 is centered on the optical axis with respect to the moving follower base plate 14 by the biasing spring 32 so as to absorb the backlash between the straight key 12b of the second group barrel 12 and the straight guide groove 14b of the moving follower base plate 14. It is biased in the radial direction. As a result, the eccentric error with respect to the center of the optical axis of the second group barrel 12 is guaranteed relative to the moving follower base plate 14.

  Also, on the outer peripheral surface of the movable follower base plate 14, two integrally formed cam followers 14a and a movable follower 14c urged to the cam groove 21e of the movable cam ring 21 by a spring are disposed. Thereby, the eccentric error with respect to the optical axis center of the moving follower base plate 14 does not depend on the component accuracy of the cam follower 14a of the moving follower base plate 14 and the cam groove 21e of the moving cam ring 21. Note that the cam follower 14a and the movable follower 14c of the movable follower base plate 14 are configured to be always in contact with the cam groove 21e of the movable cam ring 21 (FIG. 9 (engaged), FIG. Engagement))).

  Specifically, the movable follower 14c of the movable follower base plate 14 is urged by the cam groove 21e of the movable cam ring 21, so that the cam follower 14a of the movable follower base plate 14 and the cam groove 21e of the movable cam ring 21 contact each other. Touch. Thereby, the backlash between the cam follower 14a of the moving follower base plate 14 and the cam groove 21e of the moving cam ring 21 is absorbed, thereby guaranteeing the center of the optical axis.

  In this embodiment, as described above, a backlash absorbing mechanism for parts is provided between the second group barrel 12 and the movable cam ring 21 via the movable follower base plate 14. Thereby, the center of the optical axis of the second group barrel 12 is guaranteed without depending on the component accuracy of the cam follower 14a of the movable follower base plate 14 and the cam groove 21e of the movable cam ring 21.

  A compression spring 33 is incorporated on the outer peripheral side surface of the second group barrel 12. The second group lens barrel 12 is always urged rearward in the optical axis direction (image sensor side) with respect to the moving follower base plate 14 by the compression spring 33. The second group lens barrel 12 is positioned in the optical axis direction relative to the moving follower base plate 14 at a position where the stopper 14d of the moving follower base plate 14 abuts the movable pin 31 except in the vicinity of the TELE end to be described later of the zoom lens barrel. The position is determined (see FIG. 7).

  Next, the operation at the time of zooming of the second group barrel 12 in the zoom lens barrel will be described in detail.

  FIG. 8 is a development view of the inner peripheral surface of the movable cam ring 21.

  In FIG. 8, the left arrow indicates the rotation direction of the movable cam ring 21, and the upward arrow indicates the subject side. In order to give a desired amount of movement to the second group barrel 12, a cam locus 41 as shown is necessary. The cam trajectory 41 includes a normal area from the retracted position to the WIDE position (wide-angle end) and the TELE position (telephoto end), and an installation phase area necessary when assembling the components of the zoom lens barrel. The maximum movement amount L2 of the cam locus 41 in the optical axis direction exceeds the length L1 of the moving cam ring 21 in the optical axis direction as shown in the figure.

  The regular area has the following areas. This is an area in which the position control in the optical axis direction is performed by the engagement between the cam follower 12a of the second group barrel 12 and the cam groove 21d of the movable cam ring 21. This is an area in which the position control in the optical axis direction is performed by the engagement of the two cam followers 14a and the movable follower 14c of the movable follower base plate 14 with the cam groove 21e of the movable cam ring 21.

  Therefore, in the conventional structure in which the cam locus is simply developed on the inner peripheral surface of the moving cam ring, the length of the moving cam ring in the optical axis direction is increased. This means that the length in the optical axis direction when the zoom lens barrel is retracted is increased. On the other hand, in the present embodiment, the amount of movement necessary for the second group barrel 12 is ensured without increasing the length of the movable cam ring 21 in the optical axis direction.

  As can be seen from FIGS. 4 and 5, the three cam followers 12a of the second group barrel 12 and the two cam followers 14a and the movable follower 14c of the movable follower base plate 14 are shifted in the optical axis direction and have the same phase. It is arranged to become. Therefore, the cam follower 12a of the second group barrel 12 and the cam groove 21d of the moving cam ring 21, the cam follower 14a and the movable follower 14c of the moving follower base plate 14, and the cam groove 21e of the moving cam ring 21 are formed as follows. The That is, the built-in phase, the retracted position, the WIDE position, and the TELE position are formed to have the same phase (see FIG. 8).

  Here, the cam groove 21d and the cam groove 21e of the movable cam ring 21 are formed so as to trace the cam locus 41 (having substantially the same cam locus), but each covers the cam locus 41 completely. I don't mean. The cam groove 21d of the moving cam ring 21 is interrupted at m1 in the middle from the retracted position to the WIDE position and m2 in the middle from the WIDE position to the TELE position, and is opened at the rear end surface of the moving cam ring 21 in the optical axis direction. Part. The cam groove 21e of the moving cam ring 21 has a region having no gradient from m3 near the TELE position to the TELE position. In this region, even if the movable cam ring 21 rotates, the movable follower base plate 14 does not advance or retreat in the optical axis direction.

  That is, in the area from m1 to m2, the cam groove 21e of the moving cam ring 21 covers the cam locus 41. In the region from m3 to the TELE position, the cam groove 21d of the movable cam ring 21 covers the cam locus 41. As a result, the entire region of the cam locus 41 is covered.

  The retracted positions in FIG. 1 correspond to the retracted positions of the cam grooves 21d and 21e of the movable cam ring 21 in FIG. In the retracted position, the three cam followers 12a of the second group barrel 12 and the two cam followers 14a and the movable follower 14c of the movable follower base plate 14 are all in the cam grooves 21d and 21e of the corresponding movable cam ring 21. Engage with each other.

  When the movable cam ring 21 is rotated from the retracted position of FIG. 1 in accordance with the zoom operation of the imaging apparatus equipped with the zoom lens barrel, the respective parts of the second group barrel 12 and the movable follower base plate 14 operate as follows. To do. The three cam followers 12a of the second group lens barrel 12 and the two cam followers 14a and the movable follower 14c of the movable follower base plate 14 are guided by the cam grooves 21d and 21e of the movable cam ring 21, respectively, and move from the retracted position to the WIDE position. Move backward in the optical axis direction.

  As described above, the cam groove 21 d of the moving cam ring 21 is open on the rear end surface of the moving cam ring 21 in the optical axis direction. Therefore, the three cam followers 12a of the second group barrel 12 are disengaged from the cam grooves 21d of the movable cam ring 21 at m1 on the way from the retracted position to the WIDE position. In the region from m1 through the WIDE position to m2, the three cam followers 12a of the second group barrel 12 are disengaged from the cam grooves 21d of the movable cam ring 21.

  Therefore, in the area from m1 to m2, only the two cam followers 14a and the movable follower 14c of the movable follower base plate 14 are engaged with the cam groove 21e of the movable cam ring 21 (FIG. 2, FIG. (See FIG. 7). Therefore, in the region from m1 to m2, the second group barrel 12 is also moved in the optical axis direction by the movable follower base plate 14 being guided by the cam groove 21e of the movable cam ring 21. At this time, the optical axis center of the second group lens barrel 12 is guaranteed relative to the moving follower base plate 14.

  Further, as shown in FIG. 7, the movable lens 31 of the second group lens barrel 12 is in contact with the stopper 14 d of the moving follower base plate 14, so that the optical axis position is guaranteed relative to the moving follower base plate 14. . In the area from m1 to m2, the movable follower base plate 14 is guided in the optical axis direction according to the cam locus 41, so that the second group barrel 12 also does not deviate from the cam locus 41. Therefore, the position of the second group barrel 12 in the optical axis direction is also guaranteed.

  Further, when the movable cam ring 21 is rotated, the three cam followers 12a of the second group barrel 12 are cam grooves 21d from the opening of the rear end face of the movable cam ring 21 at m2 on the way from the WIDE position to the TELE position. Return to. In the region from m2 through m3 in the vicinity of the next TELE position to the TELE position, each part of the second group barrel 12 and the moving follower base plate 14 operates as follows. Again, the three cam followers 12a of the second group lens barrel 12 and the two cam followers 14a and the movable follower 14c of the movable follower base plate 14 are engaged with the cam grooves 21d and 21e of the corresponding movable cam ring 21. Will be in the double engaged state.

  However, in the region from m2 to the TELE position, the optical axis center and optical axis direction position of the second group barrel 12 are the cam follower 12a and the movable cam ring 21 of the second group barrel 12 holding the second group lens 2. It is desirable to ensure only by engagement with the cam groove 21d. The position of the second group barrel 12 in the optical axis direction is guaranteed because the cam follower 12a of the second group barrel 12 and the cam groove 21d of the movable cam ring 21 are already engaged. It is only necessary to guarantee the center of the optical axis of the second group barrel 12 with the cam follower 12a of the second group barrel 12 and the cam groove 21d of the movable cam ring 21.

  Specifically, as shown in FIG. 4, in the second group lens barrel 12, radial play is absorbed by the biasing spring 32, and the optical axis center is determined relative to the moving follower base plate 14. Therefore, the urging force of the compression spring 33 is configured to be greater than the urging spring 32 so as to cut off the relative relationship between the second group barrel 12 and the movable follower base plate 14. Along with this, the cam follower 12 a of the second group barrel 12 abuts on the cam groove 21 d of the movable cam ring 21 by the urging force of the compression spring 33.

  Accordingly, the backlash of the cam follower 12a of the second group barrel 12 and the cam groove 21d of the movable cam ring 21 is absorbed by the biasing force of the compression spring 33 against the biasing force of the biasing spring 32. Therefore, in the region from m2 through m3 near the TELE end to the TELE position, the center of the optical axis of the second group barrel 12 and the position in the optical axis direction are the three cam followers 12a of the second group barrel 12 and the moving cam ring. 21 is ensured by the engagement with the cam groove 21d.

  Thereafter, when the movable cam ring 21 is further rotated, the gradient of the cam groove 21e of the movable cam ring 21 disappears at m3 near the TELE position. Therefore, the moving follower base plate 14 does not advance or retreat in the optical axis direction even if the moving cam ring 21 rotates in the region from m3 to the TELE position. During this time, the second group barrel 12 is guided by the cam groove 21d of the movable cam ring 21 and moves forward in the optical axis direction. For this reason, in the region from m3 to the TELE position, the moving follower base plate 14 reduces the distance from the second group barrel 12 against the spring force of the compression spring 33.

  Then, at the TELE position (FIG. 3), the moving follower base plate 14 and the second group barrel 12 are closest. During this time, the moving follower base plate 14 is detached from the cam track 41. However, as described above, in the region from m3 to the TELE position, the position guarantee in the optical axis direction of the second group barrel 12 is between the cam follower 12a of the second group barrel 12 and the cam groove 21d of the movable cam ring 21. Guaranteed by engagement.

  In the zoom lens barrel according to the present embodiment, the movable follower base plate 14 is interposed between the movable cam ring 21 and the second group barrel 12, and the light from the second group barrel 12 and the movable follower base plate 14 during zooming operation. Change the axial distance. Thereby, the amount of movement required for the second group barrel 12 is secured without increasing the length of the movable cam ring 21 in the optical axis direction. There is no significant difference between the present embodiment and the conventional example in that the amount of movement necessary for the second group barrel 12 is ensured without increasing the length of the moving cam ring 21 in the optical axis direction.

  The features of the zoom lens barrel of the present embodiment are as follows.

  First, in the present embodiment, the movable cam ring 21 and the movable follower base plate 14, the movable follower base plate 14 and the second group barrel 12 are each provided with a component backlash absorbing mechanism (biasing spring 32, compression spring 33, etc.). It is said. As a result, the center of the optical axis of the second group barrel 12 is relatively guaranteed via the moving follower base plate 14 without depending on the component accuracy.

  In the present embodiment, the two cam followers 14 a and the movable follower 14 c of the movable follower base plate 14 are always engaged with the cam groove 21 e of the movable cam ring 21. Therefore, even if the cam follower 12a of the second group lens barrel 12 falls off from the cam groove 21d of the moving cam ring 21 during the magnification changing operation, the optical axis center of the second group lens barrel 12 is relatively moved via the moving follower base plate 14. It is always possible to guarantee. This ensures the necessary amount of movement for the second group barrel 12 without increasing the length of the movable cam ring 21 in the optical axis direction, and does not depend on the component accuracy for the center of the optical axis of the second group barrel 12. It can be guaranteed.

  In the present embodiment, the region from the retracted position to m1 and the region from m2 to the TELE position in FIG. 8 are configured as follows. The double cam followers 12a of the second group barrel 12 and the two cam followers 14a and the movable followers 14c of the movable follower base plate 14 are engaged with the cam grooves 21d and 21e of the corresponding movable cam ring 21. The engaged state.

  Further, in the present embodiment, as described above, the compression spring 33 is configured so that the urging force is greater than the urging spring 32, so that the double engagement state is avoided in order to guarantee the center of the optical axis. However, it is better to avoid it more actively. That is, in the region from the retracted position to m2, the cam groove 21d of the movable cam ring 21 is formed larger than the diameter of the cam follower 12a of the second group barrel 12. In the region from m2 to the TELE position, the cam groove 21e of the movable cam ring 21 is formed larger than the diameters of the cam follower 14a and the movable follower 14c of the movable follower base plate 14.

  In this case, first, in the region from the retracted position to m2 (region in the normal region), the cam follower 12a of the second group barrel 12 drops off from the cam groove 21d of the movable cam ring 21 as shown in FIG. Thus, the disengaged state is established. As a result, the movable follower base plate 14 is guided by the cam groove 21e of the movable cam ring 21 and advances and retreats in the optical axis direction, and the optical axis center and the optical axis direction position of the second group barrel 12 are guaranteed with respect to the movable follower base plate 14. Will be.

  Next, in the region from m2 to the TELE position (region in the normal region), the cam follower 14a and the movable follower 14c of the movable follower base plate 14 are connected to the cam groove 21e of the movable cam ring 21 as shown in FIG. It becomes a disengaged state. However, in this region, since the moving follower base plate 14 is urged forward in the optical axis direction by the compression spring 33, it is in contact with the front end surface in the optical axis direction of the cam groove 21e of the moving cam ring 21. As a result, the second group barrel 12 is guided by the cam groove 21d of the movable cam ring 21 and moves forward and backward in the optical axis direction.

  As described above, in the normal area m2 during the zooming operation, the cam for guiding in the optical axis direction is transferred by the moving follower base plate 14 and the second group barrel 12 to cover the cam locus 41. Even in this case, the effect obtained by the present embodiment does not change at all.

  As described above, according to the present embodiment, it is possible to secure the necessary movement amount for the second group barrel 12 without increasing the length of the movable cam ring 21 in the optical axis direction. Further, it is possible to realize a zoom lens barrel feeding cam mechanism that can guarantee the center of the optical axis of the second group barrel 12 without depending on the component accuracy.

[Other embodiments]
Although the zoom lens barrel has been described in the above embodiment, the present invention can also be applied to an imaging apparatus to which the zoom lens barrel is attached.

It is sectional drawing which shows the structure (collapse position) of the zoom lens barrel as a lens barrel which concerns on embodiment of this invention. It is sectional drawing which shows the structure (WIDE position) of a zoom lens barrel. It is sectional drawing which shows the structure (TELE position) of a zoom lens barrel. It is a disassembled perspective view which shows the structure of a 2nd lens-barrel, a movable follower base plate, and a compression spring. It is a perspective view which shows the state which assembled the 2nd group lens barrel, the movement follower base plate, and the compression spring. It is a front view of a 2nd group barrel. It is sectional drawing which follows the AA line of FIG. 6 of a 2nd group barrel. It is an expanded view of the internal peripheral surface of a moving cam ring. It is a figure which shows the non-engagement state of the cam follower of a 2nd group lens barrel, and the cam groove of a moving cam ring. It is a figure which shows the non-engagement state of the cam follower and movable follower of a movement follower baseplate, and the cam groove of a movement cam ring. It is a perspective view which shows the structure of the movable ring of the zoom lens barrel which concerns on a prior art example. It is an expanded view of the inner peripheral surface of the cam ring of the zoom lens barrel according to the conventional example. It is a figure which shows the engagement state of the cam follower of a general movable ring, and the cam groove of a cam ring.

Explanation of symbols

1 Group 1 lens (imaging optical system)
2 2 group lens (photographing optical system)
3 3 lens group (photographing optical system)
4 CCD (photographing optical system)
11 Group 1 barrel 12 Group 2 barrel (shooting barrel member)
12a Cam follower 13 Third group barrel 14 Moving follower base plate (moving member)
14a Cam follower 14c Movable follower 21 Moving cam ring (cam member)
21d Cam groove (first cam groove)
21e Cam groove (second cam groove)
32 Biasing spring (second biasing member)
33 Compression spring (biasing member)
41 Cam locus

Claims (7)

In the lens barrel that holds the photographic optical system,
A plurality of first cam followers disposed on an outer peripheral surface, and a cylindrical photographing lens barrel member that holds a part of the photographing optical system;
A plurality of second cam followers disposed on the outer peripheral surface, and a movable member movable in the optical axis direction relative to the imaging barrel member;
A plurality of first cam grooves engaging with the plurality of first cam followers and a plurality of second cam grooves engaging with the plurality of second cam followers are disposed on an inner peripheral surface, A cylindrical cam member that advances and retracts the imaging barrel member and the moving member in the optical axis direction of the imaging optical system;
A first urging member that urges the first cam follower to the first cam groove by urging the photographing barrel member and the moving member in a direction away from each other in an optical axis direction ;
A second urging member for urging the second cam follower to the second cam groove by urging the photographing barrel member and the moving member in a direction perpendicular to the optical axis direction;
A part of the first cam groove is formed with a non-engagement region in which the plurality of first cam followers are disengaged when the imaging barrel member advances and retreats in the optical axis direction. ,
When the first cam follower and the second cam follower are engaged with the first cam groove and the second cam groove, respectively, the first biasing force is greater than the biasing force of the second biasing member. A lens barrel characterized by a strong biasing force of a biasing member. The photographing optical system is an optical system capable of wide-angle photographing and telephoto photographing,
The plurality of first cam followers are located in the non-engagement area when the photographing barrel member is located in a partial area of the normal area from the retracted position in the retracted state to the wide-angle end and the telephoto end. The lens barrel according to claim 1, wherein   When the photographing barrel member is located in a region other than a partial region of the normal region, the plurality of second cam followers are in contact with the wall surface of the second cam groove by the first biasing member. The lens barrel according to claim 2, wherein the lens barrel is in a state.   4. The lens barrel according to claim 2, wherein the first cam groove is opened at an end surface in the optical axis direction of the cam member.   The non-gradient region where the gradient disappears is formed in the second cam groove, and the advancement / retraction of the moving member in the optical axis direction by the rotation of the cam member is stopped in the non-gradient region. The lens barrel according to any one of 4 to 4.   The region other than the partial region of the normal region is a first region in which position control in the optical axis direction is performed by engagement of the plurality of first cam followers and the first cam groove. The partial area is a second area in which position control in the optical axis direction is performed by engagement of the plurality of second cam followers and the second cam groove. The lens barrel according to Crab.   An imaging apparatus comprising the lens barrel according to any one of claims 1 to 6.

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