JP2005221889A - Zoom lens barrel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens barrel that can be miniaturized, in a zoom lens barrel enabling a plurality of lens groups to be driven forwards and backwards. <P>SOLUTION: In the zoom lens barrel 10, there are provided a fixing frame 11, a rotary frame 12 helicoidally combined with the fixing frame 11, a connecting frame 13 helicoidally combined with the rotary frame 12, a first and a second group lens frame 14, 16, a key-ring 17 that straight advances the connecting frame 13 and the first group frame 14, and a motor 30 rotatable bi-directionally. In zooming with this lens barrel 10, the rotary frame 12 is rotatably driven in one direction by the driving motor 30, with the first and second group lens frames 14, 16 delivered to each zooming position through the connecting frame 13. Also, in focusing, the rotary frame 12 is rotatably driven in the other direction by the motor 30, with only the second group lens frame 16 driven in the delivering direction without moving the first group lens frame 14 forwards and backwards. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a zoom lens barrel having a plurality of lens groups and capable of advancing and retracting each lens group.

Conventionally, there is a zoom lens barrel disclosed in Patent Document 1 that performs zooming and focus adjustment with a single driving source. As shown in FIG. 12, the zoom lens barrel 101 is rotationally driven by a fixed barrel 102, a single drive motor, and has double rotary barrels 103 and 104 each having a cam groove, and the rotary barrel 103. The movable cylinder 105 is driven forward and backward to hold the front group lens, and the rear group lens holding cylinder 106 is driven forward and backward by the cam groove. The two cam grooves provided in the rotary cylinders 103 and 104 are provided with two cam sections made up of stepped cams for a set corresponding to a plurality of magnifications (for example, six types of magnifications). One cam section is a focus adjustment cam section, and the other is a zooming cam section. The rotating cylinders 103 and 104 are simultaneously driven by the single drive motor to obtain a zooming state corresponding to the zooming cam section corresponding to the zooming, and focus adjustment is performed in the focusing cam section. Is called.
Patent Document 1 is Japanese Patent Laid-Open No. 9-189836.

  However, the zoom lens barrel 101 disclosed in Patent Document 1 described above has a triple cylindrical member structure of the rotary barrel 103, the movable barrel 105, and the rotary barrel 104 except for the fixed barrel 102, and the size of the barrel is small. The disadvantage is the structure. In addition, there is a problem that the zooming point is limited by the cam shape, and an arbitrary zooming cannot be selected.

  The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a lens barrel that can be reduced in size in a zoom lens barrel capable of driving a plurality of lens groups forward and backward.

  A zoom lens barrel according to claim 1 of the present invention includes a plurality of lens groups constituting a zoom optical system, a fixed frame, a rotating frame that rotates in both directions and advances and retreats in the optical axis direction with respect to the fixed frame, Provided between the fixed frame and the rotating frame, when the rotating frame rotates in one direction, the rotating frame is moved forward of the optical axis, and when the rotating frame rotates in the other direction, the rotating frame A first coupling means that moves the optical axis rearward, a key member that extends in the optical axis direction and is not rotatable about the optical axis, and is relative to the key member by a predetermined amount around the optical axis. A connecting frame that is rotatable, receives rotation of the rotating frame and abuts on the key member to be unable to rotate around the optical axis, and advances and retracts in the optical axis direction; and between the rotating frame and the connecting frame And the rotating frame until the connecting frame comes into contact with the key member. Second coupling means that rotates physically and causes the coupling frame to abut against the key member to advance or retract the coupling frame forward or backward of the optical axis according to the direction of rotation of the rotary frame. A first lens group that holds one lens group of the optical system, is rotated around the optical axis in response to the rotation rule of the key member, and advances and retracts in the optical axis direction Provided between the lens frame, the connection frame and the first group lens frame, the rotation frame rotates, the connection frame rotates together, and the first group lens frame and the connection frame rotate relative to each other. A third coupling means for advancing and retreating in the opposite direction to the advancing and retreating direction of the rotating frame, and a second lens group that is one lens group of the optical system different from the first lens group. And is relatively non-rotatable with respect to the connecting frame, and A second group lens frame that is relatively movable in the optical axis direction and advances and retracts in the optical axis direction by rotation of the rotary frame, and is provided between the second group lens frame and the rotary frame, And a fourth coupling means for advancing and retracting the second group lens frame in the optical axis direction by rotation of the rotation frame, and the first group lens frame and the second group lens frame are By the rotation of the frame, it is driven back and forth through the connecting frame.

  A zoom lens barrel according to a second aspect of the present invention is the zoom lens barrel according to the first aspect, wherein the first, second and third coupling means are coupling by a helicoid screw.

    A zoom lens barrel according to a third aspect of the present invention is the zoom lens barrel according to the second aspect, wherein the frictional force in the second coupling means is larger than the frictional force in the third coupling means.

  According to a fourth aspect of the present invention, there is provided a zoom lens barrel comprising: a plurality of lens groups constituting a zoom optical system; a first frame; and a second that rotates in both directions and advances and retreats in the optical axis direction with respect to the fixed frame. When the rotating frame rotates in one direction, the rotating frame is moved in front of the optical axis, and the rotating frame rotates in the other direction. Includes a first coupling means for moving the rotary frame to the rear of the optical axis, a key member extending in the optical axis direction and not rotatable about the optical axis, and a predetermined key around the optical axis with respect to the key member. A third frame that receives the rotation of the rotating frame, abuts on the key member and cannot rotate about the optical axis, and advances and retreats in the optical axis direction, and the rotating frame. Provided between the connecting frame and the rotating until the connecting frame abuts the key member. A second frame that rotates integrally with the frame, abuts the connecting frame against the key member, and advances or retracts the connecting frame forward or backward of the optical axis according to the direction of rotation of the rotary frame; A first lens group that is a coupling means and one lens group of the optical system is held, and is rotated around the optical axis in response to the rotation rule of the key member, and is moved forward and backward in the optical axis direction. Provided between the fourth frame and the connecting frame and the fourth frame, the rotating frame rotates, the connecting frame rotates together, and the fourth frame and the connecting frame rotate relative to each other. A third coupling means for advancing and retreating in the opposite direction to the advancing and retreating direction of the rotating frame, and a second lens group that is one lens group of the optical system different from the first lens group. Hold, relatively unrotable with respect to the connecting frame, and optical axis direction with respect to the connecting frame A fifth frame that is relatively movable and is advanced and retracted in the optical axis direction by rotation of the rotating frame; and is provided between the fifth frame and the rotating frame, and the rotation frame rotates to And a fourth coupling means for advancing and retracting the fifth frame in the optical axis direction. The fourth frame and the fifth frame are rotated by the rotation of the second frame. It is driven back and forth through the frame.

  According to the present invention, it is possible to provide a lens barrel that can be reduced in size in a zoom lens barrel capable of driving a plurality of lens groups forward and backward.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view along the optical axis in a retracted state of a camera incorporating a zoom lens barrel according to an embodiment of the present invention. 2 and 3 are cross-sectional views along the optical axis of the zoom lens barrel in the wide state and the tele state. FIG. 4 is an exploded perspective view of the zoom lens barrel. FIG. 5 is a view of the meshing state of the rotating frame of the zoom lens barrel and the drive gear as seen from the optical axis direction. FIG. 6 is a cross-sectional view seen from the optical axis direction showing a fitting state of the first group frame of the zoom lens barrel and the key tip. FIG. 7 is a development view of the cam groove in the inner peripheral portion of the rotating frame of the zoom lens barrel (the female helicoid portion is not shown). FIGS. 8A to 8C are front views in the optical axis direction showing the rotating state of the rotating frame, the second group frame, the connecting frame, and the key tip in the zoom operation, focusing operation, and collapsing operation of the zoom lens barrel. It is sectional drawing seen from. FIG. 8A shows the zoom-up operation from the retracted state to the wide state and the tele state. FIG. 8B illustrates a focusing operation, and FIG. 8C illustrates a state during a zoom-down operation or a retracting operation. 9A to 9C show the fitting state of the connecting frame and the key portion in each state of FIG. 8 and the retracted end state, and FIG. 9A is a view of A in FIG. 9B is an A ′ arrow view of FIG. 8B, FIG. 9C is an A ″ arrow view of FIG. 8C, and FIG. 8D shows a state in which the retracting operation is completed from the state of FIG.8C, and FIGS.10A to 10D show the rotation frame, connecting frame, and first group frame of the zoom lens barrel. 10A and 10B are cross-sectional views along the optical axis showing the retracted state, where FIGS. 10A and 10B show an arbitrary zoom state and a zoom-down start state, and FIGS. 10C and 10D show the collapsed state. Fig. 11 is a diagram showing changes in the amount of forward and backward movement of the first and second group lenses with respect to the focal length (rotating frame rotation angle) of the zoom lens barrel.

  Note that the photographing lens of the zoom lens barrel has an optical axis O. In the following description, the direction parallel to the optical axis O and the subject side direction is defined as + Z direction (front), and the subject image formation side direction is defined as −Z direction (rear). The rotation direction is indicated by the rotation direction when viewed from the subject side, the clockwise rotation direction is defined as + D direction, and the counterclockwise rotation direction is defined as −D direction.

  As shown in FIG. 1, the camera 1 incorporating the zoom lens barrel 10 according to the present embodiment has a camera exterior cover that is an exterior member that covers the lens barrel in addition to the zoom lens barrel 10 mounted on the camera body 2. 3, a rear lid 4 capable of opening and closing the rear part of the aperture part 2 a of the camera body 2, a finder optical system 5 disposed above the lens barrel part, a light projecting unit 7 for distance measurement, and an LCD display unit 6.

  1-4, the zoom lens barrel 10 includes a fixed frame 11 as a first frame, a rotary frame 12 as a second frame, a connecting frame 13 as a third frame, and a shutter unit. 15, a first group frame (first group lens frame) 14 that is a fourth frame that holds the first group lens 21, and a second group that is a fifth frame that holds the second group lens 22. A frame (second group lens frame) 16, a key ring 17, which is a linear guide member to which the key ring holding ring 18 is fixed, a coil spring 20, a drive gear 19, and the lens barrel are retracted, zoomed and focused. And a drive motor 30 that rotationally drives the drive gear 19 via a gear train.

  In the zoom lens barrel 10, the first and second group frames 14, 16 and the like are extended from the retracted position to the wide position where the photographing can be performed, and further to the tele position by rotating the rotating frame 12 clockwise (+ D direction). A zoom-up operation is performed. Then, the second group frame is retracted by the counterclockwise rotation (−D direction) of the rotary frame 12 at each zoom position, and the focusing operation is performed. Further, the zoom-down operation and the collapsing operation are performed by the rotation of the rotating frame 12 beyond the focus drive in the −D direction. Details of the zoom lens barrel 10 will be described below.

  The fixed frame 11 which is a constituent member of the zoom lens barrel 10 is a ring-shaped member, and has a left-handed female helicoid screw (hereinafter referred to as a helicoid screw) as a first coupling means on the inner periphery. 11a, a gear insertion opening 11b, and a rectilinear guide groove 11c along the Z direction are provided. The fixed frame 11 is fixed to the front position of the photographing aperture aperture 2a of the camera body 2.

  The drive gear 19 is a spur gear having a long gear shape, is inserted into the gear insertion opening 11b of the fixed frame 11, and is rotatably supported.

The key ring 17 is a ring-shaped plate member, and is formed by bending a rectilinear guide convex portion 17a projecting outward on the outer peripheral portion, and two upper and lower portions extending straight forward in the optical axis O direction. A key portion 17b is provided. A key ring holding ring 18 is fixed to the front side of the ring portion of the key ring 17 with screws.

  The key ring holding ring 18 is provided with three circumferential guide convex portions 18a protruding outward from the outer peripheral portion.

  The key portion 17b includes a root portion 17d having a wide circumferential direction, a key tip portion 17c having a predetermined width narrower than the root portion, and a cam portion 17e having an inclined surface connecting the root portion 17d and the key tip portion 17c. Yes. The cam portion 17e is provided on the side surface on the clockwise side of the key portion 17b when the key ring 17 is viewed from the front. The side surface on the counterclockwise side of the key portion 17b is a linear portion formed by a plane parallel to the Z direction (optical axis O direction).

  The key ring 17 to which the key ring holding ring 18 is fixed is inserted from the rear of the fixed frame 11 and the rotating frame 12 described later, and the circumferential guide convex portion 18a is inserted from the insertion port 12e of the rotating frame 12. Then, it is slidably fitted into the circumferential guide groove 12f. At the same time, the rectilinear guide protrusion 17 a is slidably fitted into the rectilinear guide groove 11 c of the fixed frame 11.

  Therefore, the key ring 17 and the key ring holding ring 18 are held so as to move forward and backward in the direction of the optical axis O together with the rotary frame 12 while being linearly guided while being rotationally restricted by the fixed frame 11.

  The key portion 17b of the key ring 17 is inserted into a guide hole 13c of the connecting frame 13 described later, and is slidably inserted into a guide groove 14b of the first group frame 14 described later. In the inserted state, the distal end portion 17c of the key portion 17b has a predetermined gap (gap rotation angle θd) in the width direction with respect to the guide hole 13c (FIG. 9A). Further, in the state where the root portion 17d of the key portion 17b is fitted in the guide hole 13c, there is no backlash in the width direction (circumferential direction) (FIG. 9D).

  Further, the key tip portion 17c of the key portion 17b is slidably fitted in the straight guide groove 14b of the first group frame 14 without any play in the circumferential direction (FIG. 6).

  The rotary frame 12 is a stepped ring-shaped member, and the left-handed male helicoid 12a and spur gear portion 12b of the first coupling means are provided on the outer peripheral portion of the rear end step portion, and the second coupling means is provided on the inner peripheral portion. A right-handed female helicoid 12c, a cam groove 12d for driving the second group frame of the fourth coupling means arranged so as to overlap the helicoid, and a circumferential guide groove 12f having an insertion port 12e at the rear of the inner periphery Provided. The rotating frame 12 is inserted into the inner peripheral part of the fixed frame 11 from the rear side, and is inserted in a state in which the male helicoid 12a is screwed into the female helicoid screw 11a. Further, the drive gear 19 meshes with the spur gear portion 12b of the rotary frame 12 (FIG. 5). Accordingly, the rotary frame 12 is driven to rotate by the drive gear 19 and is driven back and forth along the Z direction (optical axis O direction) while rotating with respect to the fixed frame 11.

  The connecting frame 13 is a stepped annular member having the same lead as the right-handed male helicoid 13a of the second coupling means on the outer periphery of the rear step portion and the female helicoid 11a of the fixed frame 11 on the front outer periphery. A left-handed male helicoid 13b as a third coupling means is provided, and has three notches 13d along the Z direction in three circumferential directions, and a rectilinear guide groove 13e is provided inside the notch. Furthermore, guide holes 13c for key insertion are provided at two locations, upper and lower, along the Z direction that penetrate the rear stepped portion.

  The connecting frame 13 is inserted into the inner peripheral portion of the rotating frame 12 from the rear side, is inserted into the female helicoid 12c by screwing the male helicoid 13a, is rotatable with respect to the rotating frame 12, and has an optical axis O. Supported to move forward and backward in the direction.

  As described above, since the tip 17c of the key portion 17b provided in the key ring 17 is inserted through the guide hole 13c, the connecting frame 13 has a gap with the guide hole 13c as shown in FIGS. 9 (A) and 9 (B). It can be rotated by a corresponding rotation angle θd.

  On the other hand, the friction torque (friction force or drive transmission torque) of the screwed portion between the male helicoid 13a of the connecting frame 13 and the female helicoid 12c of the rotating frame 12 is the first group described later with the male helicoid 13b of the connecting frame 13. It is assumed that the friction torque (friction force or load torque) of the screwed portion of the frame 14 with the female helicoid 14a is surely larger. This difference in friction torque may be caused by the viscosity of the grease applied to the helicoid screw part, or the threaded portion between the connecting frame 13 and the rotating frame 12 is elastically deformed to contact with a predetermined biasing force. Alternatively, the transmission torque and the first group frame side load torque may be differentiated by providing sliding resistance between the connecting frame 13 and the rotating frame 12 by a separate spring member.

  As described above, when the rotary frame 12 is driven to rotate in the + D direction under a state where there is a difference in friction torque (transmission torque) between the helicoid screw portions between the frame members, the connecting frame 13 is shown in FIG. ) Until the key portion 17b contacts the -D side surface 13c1 of the guide hole 13c of the connection frame 13 (integral rotation, maximum rotation angle θd). After the contact, the connecting frame 13 is fed out in the + Z direction by the female helicoid 12c without rotating. When the rotary frame 12 is driven to rotate in the −D direction, the key portion 17b of the connecting frame 13 contacts the + D side surface 13c2 of the guide hole 13c of the connecting frame 13 as shown in FIG. To the rotating frame 12 (integral rotation, maximum rotation angle θd). After the contact, the connecting frame 13 does not rotate and is retracted in the −Z direction by the female helicoid 12c.

  The first group frame 14 is a ring-shaped member, and is provided with a left-handed female helicoid 14a as a third coupling means and two straight guide grooves 14b in the upper and lower directions along the Z direction on the inner periphery. The first lens group 21 is held in front of the inner periphery, and a shutter unit 15 having a shutter blade 15a that can be opened and closed is attached to the rear inside thereof.

  The first group frame 14 is inserted into the outer peripheral portion of the connection frame 13 from the front side, and is fitted in a state in which the female helicoid 14a is screwed into the male helicoid 13b. Further, as described above, the key portion tip 17c of the key ring 17 is slidably fitted into the linear guide groove 14b with no gap in the rotational direction. Therefore, the fixed frame 11 is always supported so as to be movable forward and backward in the direction of the optical axis O in a rotation-restricted state, and is supported so as to be relatively rotatable and movable back and forth with respect to the connecting frame 13.

  When the rotating frame 12 is rotated, the first group frame 14 is rotated by the female helicoid 11a of the fixed frame 11 if the connecting frame 13 is in a state where the rotation of the connecting frame 13 is restricted by the key portion 17b (a state in which the rotating frame 12 does not rotate together). The movement amount in the Z direction and the movement amount in the Z direction by the female helicoid 12c of the connection frame 13 are moved by the movement amount. However, as described above, when the connecting frame 13 rotates with the rotating frame 12 by the gap between the guide hole 13 c and the key portion 17 b (integral rotation), the first group frame 14 is a female helicoid of the fixed frame 11. The amount of movement of the rotating frame 12 in the Z direction by 11a is different from the above Z direction by the male helicoid 13b (having the same lead as the female helicoid 11a) of the connecting frame 13 that rotates relative to the + or-direction (reverse) Since the same amount of movement in the direction) is added, the fixed frame 11 is held in a state of not moving in the Z direction.

  The second group frame 16 is a ring-shaped member, has three projections projecting to the outer periphery, and three cam followers 16b as fourth coupling means projecting outward of the projection. The three rectilinear guide protrusions 16a having a predetermined circumferential width are provided on the inner diameter side of the protrusion. The second group lens 22 is held on the inner periphery.

  The second group frame 16 is assembled in a state in which the rectilinear guide convex portion 16a is slidably fitted in the rectilinear guide groove 13e of the connecting frame 13 without any play in the circumferential direction. Further, the cam follower 16b of the second group frame 16 is inserted into the cam groove 12d of the rotating frame 12 from the rear end side and is slidably fitted. Therefore, when the rotating frame 12 is driven to rotate, the second group frame 16 moves straight relative to the connecting frame 13 in a state where the connecting frame 13 is restricted in rotation by the key portion 17b (a state where the connecting frame 13 does not rotate together). The rotating frame 12 guided and retracted relative to the fixed frame 11 is further driven back and forth along the cam groove 12d. Further, in a state in which the connecting frame 13 is rotated with the rotating frame 12, the second group frame 16 is not driven forward and backward in the cam groove 12 d, and is advanced and retracted while being rotated by the female helicoid 11 a of the fixed frame 11 together with the rotating frame 12. Driven.

  The coil spring 20 is inserted in a compressed state between the shutter unit 15 in the first group frame 14 and the second group frame 16. Therefore, the first group frame 14 and the second group frame 16 are supported so as to be able to advance and retreat in a state where a fitting play described later is removed. The fitting backlash is play in the optical axis O direction of the helicoid threaded portion of the first group frame 14 and the connecting frame 13 and in the optical axis O direction of the helicoid screwed portion of the connecting frame 13 and the rotating frame 12. The play is a backlash of the cam follower and the cam groove of the second group frame 16 and the rotary frame 12 in the optical axis O direction.

Next, the advancing / retreating operation of the zoom lens barrel 10 of the present embodiment having the above-described configuration will be described.
When the zoom lens barrel 10 is in the retracted state shown in FIG. 1, the key portion 17b of the key ring 17 has a wide root portion 17d fitted in the guide hole 13c of the connecting frame 13 so that there is no gap in the width direction. It is held (FIG. 9D).

  Therefore, in order to zoom up from the retracted state to a wide or telephoto state where the image can be taken, the drive motor 30 is driven to rotate in one direction, and the rotary frame 12 is rotated by an angle θw (FIG. 7) corresponding to the wide. Rotate and rotate clockwise (+ D direction) by an angle θt corresponding to tele or an angle corresponding to an arbitrary zoom position. The rotating frame 12 is extended in the + Z direction with respect to the fixed frame 11 while rotating.

  At this time, the key portion 17b is in contact with the side surface 13c1 of the guide hole 13c of the connection frame 13, and the rotation of the connection frame 13 in the + D direction is restricted (FIG. 9A). Is superposed on the feed amount of the rotary frame 12 and is fed in the + Z direction by the female helicoid 12c in the rotation restricted state. The first group frame 14 is always in a rotation-restricted state, moves in the + Z direction together with the connecting frame 13, and is extended to the wide position, the tele position, or an arbitrary zoom position. On the other hand, the second group frame 16 is superposed on the feed amount of the rotary frame 12 and is restricted by the connecting frame 13 so that the cam groove 12d of the rotary frame 12 has a wide position in the + Z direction, a tele position, or Any zoom position is extended, and zooming (zooming up) is performed.

  FIG. 11 shows the amount of movement of the first group lens 21 and the second group lens 22 with respect to each focal length (corresponding to the rotation angle of the rotary frame 12) and the wide end position (focal length 38 mm) of the second group lens 22. Shown as a reference. In the zoom driving state, the second group lens 22 that is a focusing lens is in an infinite (∞) in-focus position. As shown in FIG. 9A, the key portion 17b is in contact with the −D side surface 13c1 in the guide hole 13c of the connecting frame 13, and the connecting frame 13 rotates most in the + D direction with respect to the key portion 17b. This is because the cam follower 16b is in the moved position corresponding to ∞ on the cam groove 12d.

  Subsequently, in order to perform focusing, the drive motor 30 is rotationally driven in the other direction, and the rotary frame 12 is rotated counterclockwise (− by a desired focusing angle (maximum θd (FIGS. 9A to 9B)). Rotate in the D direction). The rotating frame 12 is retracted in the −Z direction while rotating with respect to the fixed frame 11. When the rotation frame 12 starts to rotate in the −Z direction, as shown in FIGS. 8A and 9A, the key portion 17 b (tip portion 17 c) is placed on the side surface 13 c 1 side of the guide hole 13 c of the connection frame 13. It is in contact. Accordingly, when the rotating frame 12 starts to rotate in the −D direction, the connecting frame 13 rotates together with the rotating frame 12 (integral rotation) due to the friction torque difference of the above-described helicoid screwing portion and rotates in the −D direction. Therefore, it is moved together with the rotary frame 12 in the −Z direction. The rotating state of the connecting frame 13 and the key portion 17b (tip portion 17c) is shown in FIGS. 8B and 9B. Moreover, the state rotated by the maximum focusing angle θd is shown in FIGS. 8C and 9C.

  As described above, when the connecting frame 13 rotates with the rotating frame 12 (integral rotation), the first group frame 14 rotates relative to the connecting frame 13 as described above. However, since the third coupling means including the male helicoid 13b of the connecting frame 13 and the first coupling means including the female helicoid 11a of the fixed frame 11 have the same lead and advance and retract in the reverse direction, The first group frame 14 is held in a stationary state where the stationary frame 11 does not move forward and backward. On the other hand, the second group frame 16 is not driven forward / backward in the cam groove 12d of the rotary frame 12 as described above in a state where the connecting frame 13 rotates with the rotary frame 12, and the rotary groove 12 At the same time, the female helicoid 11a of the fixed frame 11 is moved from the infinite focus position to the focus position at an arbitrary subject distance by the rotation in the -D direction. Focusing from ∞ to the nearest is performed by the above-described operation (FIG. 11).

  Next, the zoom-down operation will be described. When zooming down, after the zoom-up operation or the focusing operation described above, the drive motor 30 is driven to rotate in the other direction, and the rotary frame 12 is driven to rotate counterclockwise (−D direction). The rotating frame 12 is retracted in the −Z direction with respect to the fixed frame 11 while rotating. First, in the connecting frame 13, the key portion 17b (tip portion 17c) contacts the side surface 13c2 side of the guide hole 13c from the state shown in FIG. 8A or FIG. 8B (FIG. 8C). 9 (C)) and rotates together with the rotating frame 12 until the state shown in FIG. Further, when the rotary frame 12 is driven to rotate counterclockwise (−D direction), the rotation of the connecting frame 13 in the −D direction is restricted by the key portion 17b. To turn. With the rotation of only the rotary frame 12 in the −D direction, the connecting frame 13 is retracted, and the first group frame 14 is retracted to a desired zoom-down position. The second group frame 16 is retracted to a desired zoom-down position by the cam groove 12d of the rotary frame 12.

  However, since the key portion 17b (the tip portion 17c) is in contact with the side surface 13c2 of the guide hole 13c, the second group frame 16 is in a close-in-focus state in the zoom-down state. Therefore, after rotating the rotary frame 12 to a position slightly overrunning in the −D direction, the key frame 17b is returned to the + D direction and the key portion 17b is brought into contact with the side surface 13c1 of the guide hole 13c of the connecting frame 13 so that the infinite focus state is obtained. To do. Thereafter, focusing on an arbitrary distance is performed as necessary.

  FIGS. 10A and 10B show the retraction state of the rotation frame, the connection frame, and the first group frame in an arbitrary zoom state where the subject distance is infinite and a zoom-down start state. When in the arbitrary zoom state (the state after zooming up), since the connecting frame 13 is in the rotating state shown in FIG. 8A with respect to the key portion 17b, the first group frame 14 and the connecting frame 13 Although the relative position is in a state of a narrow gap G0, when the zoom-down starts, the focusing state is close to the subject distance, and the connecting frame 13 is in the state shown in FIG. 9C, and the connecting frame 13 is rotated in the −Z direction together with the rotating frame 12, so the relative position between the first group frame 14 and the connecting frame 13 is It is in a relatively wide gap G1.

  Next, the retracting operation after zooming down will be described. When the lens barrel is subsequently retracted after the zoom-down operation described above, the drive motor 30 is further rotated in the other direction, and the rotary frame 12 is rotated counterclockwise (−D direction). . The rotating frame 12 is retracted in the −Z direction with respect to the fixed frame 11 while rotating. During the retracting operation, from the zoom-down operation state to the vicinity of the retracting completion position, the key portion 17b of the key portion 17b is in contact with one side surface 13c2 of the guide hole 13c of the connecting frame 13 as shown in FIG. The relative position between the first group frame 14 and the connecting frame 13 is the same as that in the zoom-down start state shown in FIG. 10B, as shown in FIG. It is in a state of a large gap G1.

  After that, when the connecting frame 13 is further retracted in the −Z direction retracting direction and the guide hole 13c reaches the cam portion 17e of the key portion 17b, the connecting portion 13e is connected by the cam portion 17e as shown in FIG. 9D. 13 is rotated in the + D direction by the width of the base portion 17d. That is, in appearance, the connecting frame 13 is rotationally driven by the cam portion 17e of the key portion 17b. In the retracted state, the guide hole 13c and the root portion 17d are in a fitted state. By the rotational driving of the connecting frame 13 in the + D direction, the connecting frame 13 is further retracted in the rear of the rotating frame 12 by the female helicoid 12c. At the same time, the first group frame 14 and the connecting frame 13 are relatively driven to rotate, so that the first group frame 14 is brought closer to the connecting frame 13 by the male helicoid 13c. The gap G3 is narrower than the gap G1 (see FIG. 10D). Thereby, the first group frame 14 is retracted to the limit with the connecting frame 13 and a retracted state in which the distance from the second group frame 16 is very close is obtained. That is, since the first group frame 14 and the second group frame 16 are retracted to the full limit as described above in the retracted state, the total length of the lens barrel when retracted is shortened.

  As described above, according to the zoom lens barrel 10 of the present embodiment, zooming with any zooming using a single drive motor 30 and each zoom position by applying a plurality of coupling means between the frame members. It is possible to perform focusing with the lens, and the number of frame members to be configured is small, and the outer diameter of the lens barrel can be reduced. Furthermore, the length of the lens barrel in the retracted state can be shortened to the limit.

  In the zoom lens barrel 10 of the above-described embodiment, a helicoid screw is applied as a coupling means between the frame members. However, the coupling means is not limited to this, and selectively applies a cam groove and a cam follower. However, the same effect can be obtained. In addition, although the above-described zoom lens barrel 10 is applied to a silver salt camera, the same configuration can be applied to a zoom lens barrel of a digital camera.

  The zoom lens barrel according to the present invention can be applied to a zoom lens barrel that can drive a plurality of lens groups forward and backward, as a zoom lens barrel that is downsized and has a short barrel length in a retracted state.

It is sectional drawing along the optical axis in the retracted state of the camera which incorporates the zoom lens barrel which is one Embodiment of this invention. FIG. 2 is a cross-sectional view along the optical axis in the wide state of the zoom lens barrel of FIG. 1. FIG. 2 is a cross-sectional view along the optical axis of the zoom lens barrel of FIG. 1 in a tele state. FIG. 2 is an exploded perspective view of the zoom lens barrel of FIG. 1. It is the figure which looked at the meshing state of the rotating frame and drive gear of the zoom lens barrel of FIG. 1 from the optical axis direction. It is sectional drawing seen from the optical axis direction which shows the fitting state of the 1st group frame and key part front-end | tip part of the zoom lens barrel of FIG. FIG. 2 is a development view of a cam groove in an inner peripheral portion of a rotation frame of the zoom lens barrel in FIG. 1 (a female helicoid portion is not shown). FIG. 3 is a cross-sectional view seen from the front in the optical axis direction showing the rotation state of the rotating frame, the second group frame, the connecting frame, and the key tip in the zoom operation, the retracting operation, and the focusing operation of the zoom lens barrel of FIG. 8A shows the zoom-up operation from the retracted state to the wide state and the tele state, FIG. 8B shows the focusing operation, and FIG. 8C shows the zoom-down operation, or The state during the retracting operation is shown. FIG. 9A shows the fitting state of the connecting frame and the key part in each state of FIG. 8 and in the retracted end state, and FIG. 9A is a view taken in the direction of arrow A in FIG. FIG. 9B is a view taken along the arrow A ′ in FIG. 8B, FIG. 9C is a view taken along the arrow A ″ in FIG. 8C, and FIG. 9D is a view taken along the line A ′ in FIG. The state where the collapsing operation is completed from the state is shown. FIGS. 10A and 10B are cross-sectional views along the optical axis showing the retraction state of the rotation frame, the connection frame, and the first group frame of the zoom lens barrel of FIG. 1, and FIGS. A zoom-down start state is shown, and FIGS. 10C and 10D show a state before the collapse is completed and a state where the collapse is completed. It is a figure which shows the change of the back-and-forth movement amount of a 1st, 2nd group lens with respect to the focal distance of the zoom lens barrel of FIG. It is sectional drawing along the optical axis of the conventional zoom lens barrel.

Explanation of symbols

11: Fixed frame (first frame)
11a ... Female helicoid (first coupling means)
12 ... Rotating frame (second frame)
12a ... male helicoid (first coupling means)
12c ... Female helicoid (second coupling means)
12d ... Cam groove (fourth coupling means)
13 ... Connecting frame (third frame)
13a ... male helicoid (second coupling means)
13b ... male helicoid (third coupling means)
14 ... 1st group frame (1st group lens frame, 4th frame)
14a ... Female helicoid (third coupling means)
16 ... Second group frame (second group lens frame, fifth frame)
16b ... Cam follower (fourth coupling means)
17b ... Key part (key member)
17c ... Key tip (key member)
21 ... First lens group (first lens group, lens group)
22 ... Second lens group (second lens group, lens group)

Agent Patent Attorney Susumu Ito

Claims (4)

A plurality of lens groups constituting the zoom optical system;
A fixed frame,
A rotating frame that rotates in both directions and advances and retreats in the optical axis direction with respect to the fixed frame;
Provided between the fixed frame and the rotating frame, when the rotating frame rotates in one direction, the rotating frame is moved forward of the optical axis, and when the rotating frame rotates in the other direction, the rotating frame First coupling means for moving the optical axis rearward of the optical axis;
A key member extending in the optical axis direction and not rotatable about the optical axis;
The key member can be rotated relative to the key member by a predetermined amount. The rotation of the rotary frame makes contact with the key member and rotation becomes impossible around the optical axis, and the head member advances and retreats in the optical axis direction. A connecting frame to
The rotating frame is provided between the rotating frame and the connecting frame, and rotates integrally with the rotating frame until the connecting frame comes into contact with the key member, the contacting frame comes into contact with the key member, and the rotating frame. Second coupling means for advancing and retracting the connecting frame forward or backward of the optical axis according to the direction of rotation of
A first lens group frame that holds a first lens group that is one lens group of the optical system, is made unrotatable around the optical axis in response to a rotation rule of the key member, and advances and retreats in the optical axis direction When,
Provided between the connection frame and the first group lens frame, the rotation frame rotates, the connection frame rotates together, and the first group lens frame and the connection frame rotate relative to each other; A third coupling means for moving back and forth in the reverse direction by the same amount as the moving direction of the rotating frame;
A second lens group which is one lens group of the optical system different from the first lens group is held, is relatively non-rotatable with respect to the connection frame, and is relative to the connection frame in the optical axis direction. A second group lens frame that is movable in a movable manner and advances and retracts in the optical axis direction by rotation of the rotary frame;
A fourth coupling means provided between the second group lens frame and the rotating frame, for advancing and retracting the second group lens frame in the optical axis direction by rotation of the rotating frame;
A zoom lens barrel characterized by comprising:   2. The zoom lens barrel according to claim 1, wherein the first, second and third coupling means are coupling by helicoid screws.   The zoom lens barrel according to claim 2, wherein the frictional force in the second coupling means is larger than the frictional force in the third coupling means. A plurality of lens groups constituting the zoom optical system;
The first frame,
A second frame that rotates in both directions and advances and retracts in the optical axis direction with respect to the fixed frame;
Provided between the fixed frame and the rotating frame, when the rotating frame rotates in one direction, the rotating frame is moved forward of the optical axis, and when the rotating frame rotates in the other direction, the rotating frame First coupling means for moving the optical axis rearward of the optical axis;
A key member extending in the optical axis direction and not rotatable about the optical axis;
The key member can be rotated relative to the key member by a predetermined amount. The rotation of the rotary frame makes contact with the key member and rotation becomes impossible around the optical axis, and the head member advances and retreats in the optical axis direction. A third frame to
The rotating frame is provided between the rotating frame and the connecting frame, and rotates integrally with the rotating frame until the connecting frame comes into contact with the key member, so that the connecting frame comes into contact with the key member. Second coupling means for advancing and retracting the connecting frame forward or backward of the optical axis according to the direction of rotation;
A fourth frame that holds a first lens group that is one lens group of the optical system, is made unrotatable around the optical axis in response to the rotation rule of the key member, and advances and retreats in the optical axis direction; ,
The rotating frame is provided between the connecting frame and the fourth frame, and the rotating frame rotates, and when the connecting frame rotates together and the fourth frame and the connecting frame rotate relative to each other, the rotating frame A third coupling means for moving forward and backward in the opposite direction to the forward and backward direction of
The second lens group, which is one lens group of the optical system different from the first lens group, is held, relatively unrotatable with respect to the connection frame, and relative to the connection frame in the optical axis direction. A fifth frame that is movable in a movable manner and advances and retracts in the direction of the optical axis by the rotation of the rotating frame;
A fourth coupling means provided between the fifth frame and the rotating frame, for advancing and retracting the fifth frame in the optical axis direction by rotation of the rotating frame;
A zoom lens barrel characterized by comprising:

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