JP4455108B2 - Camera having zoom lens and zoom lens barrel - Google Patents

Description

  The present invention relates to a camera having a zoom lens capable of zooming and focusing, and a zoom lens barrel incorporating the zoom lens.

  As an example of a conventional retractable zoom lens barrel, in the case of a lens barrel having a general structure as shown in the enlarged sectional view of the frame member in FIG. The movable front group frame 102 and rear group frame 104 are moved from the retracted position to the wide end position and further to the tele end position by the rotation of the cam frame 101. A female helicoid screw 101a for driving the front group frame 102 forward and backward and a cam groove 101b for driving the rear group frame 104 forward and backward are provided on the inner periphery of the cam frame 101.

  In the conventional lens barrel shown in FIG. 15, when the front group frame 102 and the rear group frame 104 are retracted from the wide end position to the retracted position, the front group frame 102 is retracted by the female helicoid screw 101a. The frame 103 does not move immediately in the retracting direction from the wide end position. In some optical systems, the frame 103 is temporarily retracted in the retracting direction and then retracted toward the retracted position. In other words, the cam groove 101b is provided with a cam groove in a feeding direction with a certain margin in the wide end portion.

  In the conventional zoom lens barrel shown in FIG. 15 described above, when retracting from the wide end, the rear group frame 104 moves so as to be extended once, so that the front group frame 102 and the rear group frame 104 are at the wide end. It will be closer than the relative position at. Therefore, the separation distance d0 between the front group frame 102 and the rear group frame 104 needs to be set larger than the separation distance at the wide end. Therefore, the degree of freedom of arrangement and shape is reduced by limiting the occupied space of the front group frame 102 and the rear group frame 104, for example. Therefore, it becomes difficult to provide a lens barrel having sufficient performance. Or, the lens barrel can be downsized.

  The present invention has been made in order to solve the above-described problem, and in a zoom lens barrel, the arrangement of each component is easy, the degree of freedom in design is large, and the zoom lens barrel can be downsized. Another object is to provide a camera having a zoom lens.

A camera having a zoom lens according to the present invention is a camera having a retractable zoom lens, a focusing lens group for focusing among a plurality of lens groups constituting the zoom lens, and an optical axis for zooming the focusing lens group A retractable cam streak that is required to move in the direction of the optical axis, and that is not sufficiently moved in the optical axis direction to avoid interference with the focusing lens group between the wide end rotational position and the retracted rotational position. a cam having a zoom cam muscle is insufficient to optical required amount of movement for zooming leads to a focusing drive mechanism for driving for focusing the focusing lens unit, to function the focusing drive mechanism , when focusing the focusing lens group, the focusing lens unit caused by the zoom cam muscle Control means for controlling the focusing drive mechanism so as to move the focusing lens group by adding the insufficient movement amount to the movement amount for focusing.

  According to the present invention, it is possible to provide a zoom lens barrel or a camera having a zoom lens in which the arrangement of the frame member is easy, the degree of freedom of design is large, and the size can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing an appearance of a zoom lens barrel that is an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the photographing optical axis in the retracted state of the lens barrel of the silver halide camera to which the zoom lens barrel is attached. FIG. 3 is a cross-sectional view of the zoom lens barrel taken along the photographing optical axis in a wide state where photographing is possible. FIG. 4 is a cross-sectional view of the zoom lens barrel along the photographing optical axis in a telephoto state where photographing is possible. 5 and 6 are exploded perspective views of the zoom lens barrel. FIG. 7 is an exploded perspective view of the focus unit built in the zoom lens barrel. FIG. 8 is a cross-sectional view around the feed shaft portion constituting the focusing drive mechanism portion of the focus unit, as seen from the direction of arrow E in FIG.

  In the following description, the subject side of a zoom lens barrel (described as a lens barrel) is the front side (the forward direction is + Z), and the imaging side is the rear side (or the back side) ( The backward direction is taken as the -Z direction). The rotation direction is indicated by the rotation direction when viewed from the front side.

  The lens barrel 110 of the present embodiment is a lens shutter type zoom lens barrel incorporated in the silver halide camera 100 as shown in FIG. 2 and the like, and the camera 100 incorporates a zoom optical viewfinder device. It shall be.

  The lens barrel 110 is fixed to the fixed frame 1 as a fixed frame 1 supported by the camera body 130 in the camera exterior cover 120 and a frame member incorporated in the fixed frame 1 as shown in FIGS. The rotary frame 2 is supported so as to be freely rotatable and reciprocated, the rotation frame is restricted with respect to the fixed frame 1, the moving frame 4 moves forward and backward with the rotary frame 2, and rotates with the rotary frame 2, and moves forward and backward with respect to the moving frame 4. The cam frame 3 to be driven, the float key 5 that is restricted by the moving frame 4 and moved forward and backward together with the cam frame 3, the rotation that is restricted by the float key 5, and the first that is driven forward and backward by the cam frame 3. Energizing the group frame 6 and the focus unit 7 and the third group frame 8 which are restricted in rotation by the float key 5 and driven to advance and retreat by the cam frame 3, and in the direction in which the focus unit 7 and the third group frame 8 are separated from each other. Do A biasing spring 9 formed by a compression spring, and a focusing optical system that is held by the first group lens 11 and the second group frame 23 held by the first group frame 6 as a photographing optical system (zoom lens) having an optical axis O. A second group lens 12 that is a lens group, a third group lens 13 held by the third group frame 8, a bellows light-shielding rubber 17 disposed between the first group frame 6 and the focus unit 7, and each frame member It mainly has ring-shaped light shielding rubbers 18, 19, and 20 disposed between them.

  The fixed frame 1 is an annular member, and the fixed frame 1 is provided with a female helicoid screw (hereinafter referred to as a helicoid screw) 1a and a rectilinear groove 1b overlapping the helicoid on the inner periphery. The long gear insertion recess 1c along the optical axis O is provided in the inner peripheral portion.

  Of the rectilinear grooves 1b, the rectilinear grooves 1b1 disposed below are provided with two pin holes 1f and screw holes 1e. Zoom detection pins 37A and 37B are inserted into the two pin holes 1f, respectively, so that they can be protruded and retracted in a state in which their tip portions protrude from the outer peripheral side into the rectilinear groove 1b1. A wide detection switch contact piece 38A, a tele detection switch contact piece 38B and a detection switch common contact piece 39 constituting the zoom position detection switch unit 40, which is the zoom encoder 89, are provided at the outer peripheral position of the fixed frame 1 outside the rectilinear groove 1b1. 72 and 73 are screwed and fixed to the screw holes 1e and the like. The lower end of one zoom detection pin 37 </ b> A is in contact with the rear end 39 a of the common contact piece 39, and the lower end of the other zoom detection pin 37 </ b> B is in contact with the front end 39 b of the common contact piece 39. The front end portions 39a and 39b are always in contact (on state) with the wide detection switch contact piece 38A and the tele detection switch contact piece 38B. When one of the zoom detection pins 37A and 37B is pressed by a guide projection 4a (described later) of the moving frame 4 that has been extended, the wide detection switch contact piece 38A and the tele detection switch contact piece 38B are switched to the OFF state, and the movement frame 4 wide end positions or tele end positions are detected. Note that the end brush portions of the wide detection switch contact piece 38A, the tele detection switch contact piece 38B, and the common contact piece 39 are held in contact with a connection flexible printed circuit board (not shown), and the output is input to a CPU 91 described later. Is done.

  A rotary frame driving long gear 36 is inserted into the gear insertion recess 1c, and the long gear 36 is mounted by a front shaft hole 1d and a gear mounting plate 36a fixed at the rear portion, and the rotation axis is an optical axis. O is supported in parallel with O.

  The long gear 36 is rotationally driven by the zoom motor 64 via the gear train 67 and the like during zoom driving. That is, as shown in FIG. 1, the pinion 65 fixed to the output shaft of the zoom motor 64 meshes with the input side gear of the gear train 67, and the output gear side of the gear train 67 meshes with the screw gear 68 side. ing. The rotation of the screw gear 68 is transmitted to the output gear 69 side. Since the output gear 69 is always meshed with the long gear 36, the rotation of the zoom motor 64 is transmitted to the long gear 36 side.

  The amount of rotation of the zoom motor 64 is detected by a photo interrupter 66 that is a zoom encoder 89 that detects the amount of rotation of the slit plate 65a fixed to the zoom motor output shaft.

  The rotating frame 2 is an annular member, and the rotating frame 2 is provided with a gear portion 2c and a male helicoid 2a on the outer peripheral portion of the rear end. Further, a circumferential guide groove 2e having cam portions 2f and 2g along the inner periphery is provided in the rear inner peripheral portion, and a plurality of concave portions in a state of being recessed from the rear end surface 2d in a state corresponding to the cam portions 2f and 2g. 2i is provided. In addition, a plurality of rectilinear grooves 2b along the optical axis O direction are provided in the inner peripheral portion.

  The rotating frame 2 is fitted into the inner peripheral portion of the fixed frame 1 by screwing the male helicoid 2 a with the female helicoid 1 a on the inner peripheral portion of the fixed frame 1. The rotating frame 2 is rotationally driven by a long gear 36 attached to the fixed frame 1 via a gear portion 2 c that meshes with the long gear 36, and moves forward and backward in the direction of the optical axis O while rotating with respect to the fixed frame 1.

  The moving frame 4 is an annular member, and the moving frame 4 includes a plurality of guide protrusions 4a protruding in the outer diameter direction on the outer peripheral portion of the rear end surface portion 4f, and outwardly protruding forward of the guide protrusions 4a. A plurality of guide pins 4d, a female helicoid 4b on the inner peripheral portion, and a rectilinear groove 4c along the optical axis O direction, and two spiral escape grooves penetrating the inner and outer peripheral portions 4e is provided.

  The moving frame 4 is inserted into the inner periphery of the rotating frame 2 while being rotatably fitted in a state in which the guide protrusion 4a is slidably fitted into the rectilinear groove 1b of the fixed frame 1. In the inserted state, the guide pin 4d is slidably fitted into the circumferential guide groove 2e of the rotating frame 2. Accordingly, the movable frame 4 moves forward and backward in the state of being integrated with the rotary frame 2 in the direction of the optical axis O at the inner peripheral portion of the rotary frame 2 in a state where the rotation of the fixed frame 1 is restricted.

  The cam frame 3 is an annular member, and the cam frame 3 is provided with a male helicoid 3a on the outer periphery of the rear end. A plurality of guide protrusions 3e are provided on the rear inner periphery. In addition, a female helicoid 3b and three cam grooves 3c and 3d are provided on the inner peripheral portion as zoom cams that are inclined with respect to the optical axis O direction. Further, two guide pins 14 protruding outward are fixed to a portion where the rear end male helicoid 3a is provided.

  The cam groove 3 c is a cam groove that fits with a cam follower 15 of a second group guide frame 21 of the focus unit 7 described later, and is a focusing lens that is held on the second group frame 23 via the second group guide frame 21. This is a zoom cam for advancing and retracting the second group lens 12 in the optical axis O direction for zooming. However, the cam groove 3c has a cam streak (cam groove portions 3c1 to 3c1 in FIG. 10) that is insufficient with respect to the required movement amount as described later in order to limit the required optical movement amount of the second group lens 12 during zooming. 3c3) is formed. As will be described later, the correction driving of the second lens group 12 is performed by adding the amount of movement insufficient for zooming (the amount of movement L1 in FIG. 10) to the in-focus driving amount during the in-focus driving.

  The cam groove 3d is a cam groove fitted to the cam follower 16 of the third group frame 8, and is used to advance and retract the third group lens 13 held by the third group frame 8 in the optical axis O direction for zooming. This is a zoom cam.

  The cam frame 3 is fitted in a state in which the male helicoid 3a is screwed to the female helicoid 4b on the inner peripheral portion of the moving frame 4, and the rotating frame 2 moves straight with the guide pin 14 inserted through the escape groove 4e. The groove 2b is slidably fitted into the groove 2b. Accordingly, the cam frame 3 rotates together with the rotating frame 2 and moves forward and backward in the optical axis O direction relative to the moving frame 4.

  The float key 5 is a ring-shaped member, and the float key 5 includes a plurality of guide protrusions 5a protruding in the outer radial direction at the outer peripheral rear end portion, and a guide groove 5d extending in the circumferential direction at the outer peripheral rear portion, A rectilinear groove 5e along the optical axis O direction and three rectilinear guide grooves 5b and 5c along the optical axis O direction penetrating the inner and outer peripheries are provided on the outer peripheral portion.

  The float key 5 is assembled in a state where the guide protrusion 5a is slidably fitted into the rectilinear groove 4c of the moving frame 4, and the guide protrusion 3e of the cam frame 3 is slidably fitted into the guide groove 5d. Therefore, the rotation of the float key 5 is restricted by the moving frame 4 and moves forward and backward integrally with the cam frame 3 in the optical axis O direction.

  The first group frame 6 is a ring-shaped member, and the first group frame 6 is provided with a male helicoid 6a on the outer peripheral portion of the rear end and a straight guide convex portion 6b extending in the optical axis O direction on the inner peripheral portion. . Further, the first lens group 11 is held in the central opening, and the decorative plate 10 is fixed to the front surface thereof.

  The first group frame 6 is incorporated by sliding the straight guide convex portion 6 b into the straight guide groove 5 b of the float key 5 slidably and screwing the male helicoid 6 a with the female helicoid 3 b of the cam frame 3. Accordingly, the first group frame 6 moves straight in the direction of the optical axis O as the cam frame 3 rotates and advances and retracts while being restricted by the float key 5.

  As shown in FIGS. 2, 5, and 7, the focus unit 7 is mounted with a second group guide frame 21, a focusing lens, and a shutter drive source, and is mounted on the rear side of the second group guide frame 21. 22, a shutter blade, a light shielding blade, a second lens group that is a focusing lens, and the like are incorporated, and a second group frame 23 that is driven relative to the second group guide frame 21 in the optical axis O direction during focusing, A shutter lid 25 attached to the front surface of the second group frame 23, a frame lid 26 attached to the front surface of the second group guide frame 21, and a guide rod 27 that slidably supports the second group frame 23 in the direction of the optical axis O. And mainly.

  The LD base plate 22 is a frame member having a central opening 22a, and on the front side thereof, a plunger solenoid device 55 that is a driving source of shutter blades and light shielding blades, a focus motor 41 that is a driving source of focusing drive, A focus drive gear train 46, a focus drive mechanism for driving the second group frame 23 forward and backward via the focus drive gear train 46, a focus motor rotation amount detection photo interrupter 61, and a shutter blade movement position A photo interrupter 63 for detection and the like are incorporated. The LD base plate 22 is temporarily fixed to the second group guide frame 21 with a hook 22c from the back side, and then a screw 71a inserted into the screw insertion hole 22b and a screw 71b inserted through the screw insertion hole 22d. The second group guide frame 21 is fixed by screwing.

  The plunger solenoid device 55 includes a solenoid part 58, a plunger 56, and a plunger spring 57 that is interposed between the solenoid part and the plunger and biases the plunger in the protruding direction (shutter blade closing direction). ing. The sliding direction of the plunger 56 is a direction along a plane perpendicular to the optical axis O. An end portion 29b of a shutter drive lever 29 described later abuts on the tip of the plunger 56.

  The focus motor 41 has an output shaft along a direction parallel to the optical axis O, and a pinion 42 is fixed to the output shaft. The pinion 42 meshes with the first gear 47 of the focusing drive gear train 46. The rotation amount of the output shaft is detected by a photo interrupter 61 that is a focus encoder 60 that detects the rotation of the slit plate 62 attached to the shaft of the gear 48 in the focusing drive gear train 46.

  The final stage gear 49 of the focusing drive gear train 46 has a feed screw 50 of a focusing drive mechanism portion parallel to the optical axis O fixed integrally, and the feed screw 50 has a focusing drive mechanism. The drive nut 52 of the part is screwed. The details of the focusing drive mechanism around the feed screw 50 will be described later with reference to FIG.

  The second group guide frame 21 is a frame member having a central opening 21a, and is provided with convex portions 21b at three outer peripheral portions, and the cam followers 15 are fixed to the convex portions, respectively.

  The convex portion 21b of the second group guide frame 21 built in the focus unit 7 is supported by being linearly guided in the direction of the optical axis O while being fitted in the linear guide groove 5b inside the float key 5. The second group guide frame 21 is relatively advanced and retracted with the rotation of the cam frame 3 through the cam follower 15 fitted in the cam groove 3c of the cam frame 3 during zoom driving.

  The second group frame 23 is a frame member having a shutter opening 23a at the center, and a second group lens and a shutter device are incorporated therein. That is, the second group frame 23 includes a pair of shutter blades that hold the second group lens 12 (FIG. 2) on the rear side of the opening 23a and open and close the photographing optical path as a shutter device on the front side. One shutter blade 31 and second shutter blade 32 are rotatably supported by a support pin 23d and a support pin 23e, which are a pair of shafts. Further, a light shielding blade 33 that shields the leakage of photographing light as a shutter device is rotatably supported by a support pin 23f. Further, a shutter drive lever 29 is rotatably attached to a shaft portion 23g protruding in the optical axis O direction on the rear side upper portion through a shaft hole 29a. A sleeve 28 parallel to the direction of the optical axis O is bonded and fixed to the upper part of the second group frame 23. An anti-rotation guide convex portion 23b is provided that protrudes outward at a position facing the optical axis O of the sleeve.

  First, the sleeve 28 is inserted into the second group frame 23 with a backlash. The second group frame is positioned with a jig or the like so that the inner diameter portion of the sleeve is positioned parallel to the optical axis O of the second group lens 12 and spaced from the optical axis O by a predetermined distance. It is bonded and fixed to 23. The sleeve 28 is fitted with a guide rod 27 that slidably supports the second group frame 23.

  The shutter drive lever 29 is a driven member that is driven by the plunger 56 and is a drive member that rotationally drives the shutter blades including the light shielding blades. The shutter drive lever 29 is inserted through a shaft hole 29a that is rotatably fitted to the shaft portion 23g, an end portion 29b that contacts the tip of the plunger 56, and a pin insertion long hole 23c of the second group frame 23. Then, it has a shutter drive pin 29c that protrudes forward and engages the shutter blade and the light shielding blade.

  The shutter drive lever 29 is urged clockwise (viewed from the front) by a shutter spring 30. The urging direction is a direction in which the end portion 29b of the shutter drive lever 29 is in contact with the distal end side of the plunger 56, and a direction in which the shutter blades 31, 32 and the light shielding blade 33 are opened. The biasing force of the shutter spring 30 against the shutter drive lever 29 is weaker than the biasing force of the biasing spring 57 on the plunger 56 side. Therefore, when the plunger solenoid device 55 is turned off, the shutter drive lever 29 is rotationally driven in the shutter closing direction via the plunger 56 by the biasing force of the biasing spring 57.

  Since the shutter drive lever 29 and the plunger 56 move relative to each other in the direction of the optical axis O during focus driving, the end portion 29b of the shutter drive lever 29 is light-tight in order to maintain a contact state with the tip of the plunger 56. It has a shape extending in parallel with the direction of the shaft hole 29a which is parallel to the direction of the axis O.

  The first shutter blade 31 has a light shielding portion that can open and close the shutter opening 23 a in cooperation with the second shutter blade 32. The shutter blade 31 is rotatably supported in a state where the shutter blade 31 is fitted into the support pin 23d on the front side of the second group frame 23 and the drive slot is fitted into the drive pin 29c of the shutter drive lever 29. The

  The second shutter blade 32 has a light-shielding portion having an opening edge that can open and close the shutter opening 23 a in cooperation with the first shutter blade 31. That is, the second shutter blade 32 forms a biting portion (overlapping portion) on the opening 23 a in the shutter closed state with respect to the first shutter blade 31. The shutter blade 32 is fitted into the support pin 23e in a state of being superimposed on the front surface of the shutter blade 31 on the front side of the second group frame 23, and the drive elongated hole is fitted into the drive pin 29c of the shutter drive lever 29. In such a state, it is supported so as to be rotatable.

  The light shielding blade 33 blocks light leakage from the overlapping portion of the shutter blades 31 and 32 in a state where the shutter opening portion 23a is shielded by the shutter blades 31 and 32, and when the shutter is opened, the shutter opening together with the shutter blade 31 It has a light-shielding part that can be retracted from the part 23a. The light shielding blade 33 is arranged in a state where the shutter blade 32 is sandwiched between the shutter blades 31 while covering the edge of the light shielding portion on the front surface side of the shutter blade 32 on the front surface side of the second group frame 23. . In the attached state, the support pin 23f is fitted, and the drive elongate hole is fitted to the drive pin 29c of the shutter drive lever 29 so as to be rotatably supported.

  A light shielding sheet 24 is further placed on the front surface of the light shielding blade 33 to cover it. The light shielding sheet 24 is provided with a central opening 24a having the same size as the shutter opening 23a, a relief hole 24c of the drive pin 29c, a relief 24b of the second group frame biasing spring 35, and the like.

  The shutter lid 25 is locked to the front surface of the second group frame 23 in which the shutter blades 31 and 32, the light shielding blade 33, and the light shielding sheet 24 are incorporated by the locking pins 23h, 23i, and 23j of the second group frame 23. Are installed and unitized. The shutter cover 25 is provided with a relief hole 25c of the drive pin 29c, a relief portion 25b of the second group frame biasing spring 35, and the like.

  The unitized second group frame 23 slides the guide projection 23b from the front side of the second group guide frame 21 to a guide recess 21d formed in parallel with the optical axis O of the second group guide frame 21. It is mounted in a state where it is freely inserted. Further, the frame lid 26 is fitted to the front surface of the second group guide frame 21 with the positioning pin of the guide frame in the mounted state, and the locking hole portion 26b of the frame lid 26 is hooked to the hook portion of the second group guide frame 21. 21f is engaged to provide a temporarily fixed state. Therefore, the guide rod 27 is inserted into the rod support hole 26c of the frame lid 26, and the tip portion thereof is press-fitted into the rod support hole 21c of the second group guide frame 21 and fixed. In the fixed state, the second group frame biasing spring 35 is inserted into the guide rod 27 between the frame lid 26 and the second group frame 23 in a compressed state.

  The focusing drive mechanism unit incorporated in the LD base plate 22 described above includes a feed screw 50 parallel to the optical axis O fixed integrally to the final gear 49 of the gear train 46 driven by the focus motor 41, and a feed screw. 50, a driving nut 52 that is screwed into the second group frame 23, and a rear projection 23k having one apex provided on the second group frame 23 side and a rear projection 23m having two apexes (FIG. 7). , 8). Both end shaft portions 51 of the feed screw 50 are rotatably supported by the LD base plate 22 in the shaft hole 22 c and the shaft hole 21 e of the second group guide frame 21. The drive nut 52 has a convex portion 52a, and the convex portion 52a is slidably fitted into a concave portion 21h formed in parallel with the axis of the feed screw 50 of the second group guide frame 21. . Therefore, when the final gear 49 rotates, the drive nut 52 moves in a direction parallel to the optical axis O (Z direction) along the feed screw 50 in a state where the rotation is restricted (FIG. 8). Further, the projecting portion 23k and the projecting portion 23m of the second group frame 23 are always in contact with the front side of the driving nut 52 by receiving a rearward biasing force W0 by the biasing spring 35.

  When the output shaft of the focus motor 41 is rotationally driven during focusing driving, the driving nut 52 moves via the feed screw 50 as the final gear 49 rotates, so that the second group frame 23 is used for driving. It is pressed against the urging force W0 of the urging spring 35 through the nut 52, moves forward and backward in the Z direction parallel to the optical axis O relative to the second group guide frame 21 and the LD base plate 22, and is focused. Driven.

  At the time of the focusing drive, the cam follower 15 of the second group guide frame 21 has an optically required moving amount for zooming of the second group lens 12 in the cam groove 3c of the cam frame 3 described above during the previous zooming drive. On the other hand, when it is positioned on the cam groove portion that is insufficient (cam groove portions 3c2 and 3c1 shown in FIG. 10), the movement amount for correcting the zooming shortage is added to the in-focus drive amount to add the second group guide frame 21. The second group frame 23 is driven back and forth. Details of the operation will be described later.

  The third group frame 8 is a disk-shaped frame member that holds the third group lens 13 in the central opening, and the third group frame is provided with three rectilinear guide convex portions 8a on the outer peripheral portion, Three cam followers 16 are fixed to the convex portions, respectively.

  The third group frame 8 has an optical axis O at a rear position of the focus unit 7 in a state in which the straight guide protrusion 8a is slidably fitted in the straight guide groove 5c of the float key 5 at the inner periphery of the float key 5. It is inserted so that it can move forward and backward. The cam follower 16 of the third group frame 8 is slidably fitted into the cam groove 3 d on the inner periphery of the cam frame 3. Accordingly, the third group frame 8 moves forward and backward by the cam groove 3d as the cam frame 3 rotates and advances and retracts while being guided linearly in the direction of the optical axis O.

  A biasing spring 9 that is a compression spring is inserted between the third group frame 8 and the LD base plate 22 of the focus unit 7, and a biasing force is always acting in the direction of separation. Accordingly, in the state where there is no fitting backlash between the cam follower 16 of the third group frame 8 and the cam groove 3d and no backlash between the cam follower 15 of the second group guide frame 21 and the cam groove 3c. 8 and the second guide frame 21 (second group frame 23) move forward and backward.

  An electrical circuit of the camera 100 to which the lens barrel 110 of this embodiment is attached will be described with reference to a circuit block configuration diagram of FIG.

  As shown in FIG. 11, the electric circuit of the camera 100 includes a camera driving power source (battery) 92, a CPU 91 that is a control unit that controls the entire camera, a main switch 93 that is a main power switch of the camera 100, and a lens. A zoom switch 94 for instructing zoom driving of the lens barrel 110, a release switch 95 for instructing start of photographing, a focus motor driver 96 for driving the focus motor 41, the focus motor 41, and various kinds of camera control RAM 97 for storing the above-mentioned data, zoom motor driver 98 for driving the zoom motor 64, zoom motor 64, distance measuring means for measuring the object distance and obtaining the focusing drive data of the lens barrel 110 ( A focusing circuit comprising a distance measuring circuit 99 and a photo interrupter 61 (FIG. 7) is detected. Zoom position data of the lens barrel (cam frame 3) of the focus encoder 60 including the photo interrupter 61 (FIG. 7), the zoom position detection switch unit 40 (FIG. 5), and the photo interrupter 66 (FIG. 1). And a zoom encoder 89 for obtaining (rotational angle position data).

Next, the advancing / retreating operation of each lens frame in the lens barrel 110 of the present embodiment having the above-described configuration will be described.
In the present lens barrel 110, in a non-photographing state, the lens frames such as the rotating frame 2, the cam frame 3, the first group frame 6, and the focus unit 7 are retracted substantially inside the fixed frame 1 shown in FIG. Has been brought into position.

  When the main switch 93 is turned on, various controls of the camera 100 are started under the control of the CPU 91. In the retracted lens barrel 110 in FIG. 2, the rotation frame 2 is rotated through the long gear 36 to rotate the rotation frame 2, the cam frame 3, the first group frame 6, the focus unit 7, and the third group frame 8. Are fed out in the direction of the optical axis O, and the wide state of FIG. Specifically, the rotating frame 2 is fed forward through the female helicoid 1a of the fixed frame 1 as the rotation frame 2 rotates. The moving frame 4 is fed forward together with the rotating frame 2 without rotating. The cam frame 3 is fed out while rotating together with the rotary frame 2, but the feeding position is drawn out through the female helicoid 4 b of the moving frame 4, so that the cam frame 3 is drawn out further forward than the cam frame 3. The float key 5 is fed out together with the cam frame 3 in a state in which the rotation is restricted by the moving frame 4. Further, the first group frame 6 is drawn forward from the cam frame 3 via the female helicoid 3 b of the cam frame 3 in a state in which the rotation is restricted by the float key 5. The focus unit 7 and the third group frame 8 are fed out by the cam grooves 3 c and 3 d of the cam frame 3 in a state where the rotation is restricted by the float key 5.

  Thereafter, when the zoom switch 94 is operated to the telephoto side (and further to the wide side), the first group frame 6, the focus unit 7, the third group frame 8 and the like are respectively associated with the rotation of the rotary frame 2 and the cam frame 3. It is extended to the zoom position of FIG.

  The arrival of the first group frame 6, the focus unit 7, and the third group frame 8 at the wide end position or the tele end position (corresponding to the rotational angle position of the cam frame 3) is a zoom position detection. It is detected by an off signal of the switch unit 40. Further, the rotation angle position of the cam frame 3 that gives an arbitrary zoom position other than the wide end position and the tele end position of each frame member is detected after the zoom position detection switch unit 40 detects that the wide end rotation position has been reached. Obtained by the rotation amount data of the zoom motor 64 based on the output of the photo interrupter 66.

  Focusing drive of the focus unit 7 is performed based on subject distance data fetched from the distance measuring means 99 by the first operation of the release switch 95. That is, based on the subject distance data, the focus motor 41 is driven by the control of the CPU 91, and the second group frame 23 built in the focus unit 7 by the focus drive mechanism unit is lighted with respect to the second group guide frame 21. Advancing and retreating is relatively performed along the axis O direction, and focusing driving is performed. In the case of the present embodiment, at the time of the focus drive, if the zoom extension position is insufficient from the normal zoom position as described later, the shortage is added and the focus drive is performed.

Next, details of the trajectories of the cam grooves 3c and 3d provided in the cam frame 3 in the lens barrel 110 of the present embodiment, the advance / retreat operation of each frame member during zoom driving, and the amount of movement during zoom driving are insufficient. The details of the operation for correcting at the time of in-focus driving will be described with reference to FIGS.
FIG. 9 is a development view showing the shape of the female helicoid and the cam groove in the inner peripheral portion of the cam frame in the lens barrel of the present embodiment. FIG. 10 is an enlarged view of a portion P in FIG. 9 and shows a detailed shape of the cam groove.

  When the zoom frame is zoomed up (including setup drive) from the retracted state to the wide state of the zoom lens barrel, the cam frame 3 is moved from the retracted rotation position (angle) to the wide rotation position (angle). It is rotated counterclockwise (+ θ direction in FIG. 9) at the tele-rotation position (angle). As the cam frame 3 rotates counterclockwise, the cam follower 15 moves to corresponding positions of the retracted rotation position θ2C, the wide end rotation position θ2W, and the tele end rotation position θ2T. As the cam follower 15 moves, the second group frame 23 moves to the respective zoom movement positions. On the other hand, the cam follower 16 moves to the corresponding positions of the retracted pivot position θ3C, the wide end pivot position θ3W, and the tele end pivot position θ3T. The third group frame 8 is moved to each zoom position by the movement of the cam follower 16.

  However, the cam groove 3c is short in the optical axis O direction with respect to the optically required movement amount (trajectory) during zooming of the regular second lens group 12 only in the range between the retracted position and the wide position. It has a trajectory giving (a trajectory partially translated in the -Z direction).

  Explaining with an enlarged view of the cam groove in FIG. 10, regular optical necessity at the time of zoom driving of the second group lens 12 held via the second group guide frame 21 (second group frame 23) of the focus unit 7. The cam groove 3c 'that gives the amount of movement is formed by a cam groove portion 3c3' as a retracted cam streak of the cam frame 3, a cam groove portion 3c2 'as a zoom cam streak, and a cam groove portion up to the tele end, of which the cam groove portion 3c2' In addition, it has a shape having a peak point forward in the direction of the optical axis O from the wide end rotation position θ2W toward the retractable rotation position θ2C.

  On the other hand, the cam groove 3c of the cam frame 3 in the present embodiment is formed by a cam groove 3c3 as a retracted cam line, cam groove parts 3c2 and 3c1 as a zoom cam line, and a cam groove part to the tele end. The cam groove 3c is retracted to the −Z side from the cam groove 3c ′ in the range from the retracted rotation position θ2C of the cam frame 3 to the rotation position θ2F of the bending point F0 past the wide end rotation position θ2W. Has a trajectory. That is, the cam groove 3c is a cam groove 3c1 having no inclination and bent along the direction orthogonal to the optical axis O from the turning point rotation position θ2F toward the wide end rotation position θ2W as zoom cam streaks, and the cam groove 3c1. Subsequently, the cam groove 3c2 has a peak shape in the vicinity of the wide end rotation position θ2W, and the cam groove 3c4 as a collapsed cam streak descends to the retracted position after the peak following the cam groove 3c2. The cam groove 3c is a cam groove portion that is insufficient for the above-mentioned required moving amount in which a part of the cam groove portions 3c2 'and 3c3' of the cam groove 3c 'is translated by a distance L1 in the -Z direction.

  When the cam follower 15 is extended by the cam groove 3c from the retracted rotation position θ2C toward the wide end rotation position θ2W during zoom driving, the cam follower 15 is extended later than the retracted rotation position θ2C as compared with the case of extending by the cam groove 3c ′. In this state, the distance reaches the cam groove 3c2 with respect to the wide end rotation position θ2W in a state where the distance L1 is insufficient. Thereafter, when passing through the cam groove 3c1, the shortage of the cam groove 3c ′ with respect to the cam groove 3c2 ′ gradually decreases, and when the rotation position θ2F of the bending point F0 is reached, the shortage disappears. The cam groove 3c coincides with the cam groove 3c ′ at the rotation position, and the cam follower 15 is located at the same position. Thereafter, until the tele end rotation position θ2T, the cam follower 15 moves on the cam groove 3c having the same locus as the cam groove 3c ′.

  As described above, between the vicinity of the wide end rotation position of the cam frame 3 and the retracted rotation position, the cam groove 3c ′ that gives the necessary optical movement amount during zoom driving is provided as the cam groove 3c of the cam frame 3 on the −Z side. The reason for giving a trajectory (in other words, insufficient zooming out) in the direction of the optical axis O to the necessary movement amount displaced in the second direction is that the cam follower 15 is fixed when retracting from the wide position to the retracted position. To avoid interference (collision) between the guide frame 21 (actually, the front end surface of the frame lid 26) and the first group frame 6 (actually, the rear end surface of the frame portion that holds the first group lens 11). It is.

  Specifically, when the cam frame 3 is rotated from the wide end rotation position toward the collapsible rotation position, the first group frame 6 is gradually retracted along the female helicoid 3b. On the other hand, when the second group guide frame 21 having the cam groove 3c ′ is similarly turned from the wide end turning position toward the retracted turning position, the cam follower 15 moves along the cam groove 3c ′. Since the cam groove 3c 'has a peak from the wide end rotation position to the retraction rotation position as described above, the first group is located at the closest rotation position θ2P' which is slightly beyond the peak point. The rear end surface of the frame 6 and the front portion of the second group guide frame 21 are very close to each other. Therefore, since both may interfere when approaching, the arrangement and shape of the second group guide frame 21 including the first group frame 6 and the second group frame 23 are limited, and the degree of freedom is increased. Less. Note that the state in which the first group frame 6 and the second group guide frame 21 approach is similar to the state in which the cam frame 3 is rotated from the retracted rotation position toward the wide end rotation position. It becomes.

  Therefore, in the lens barrel 110 of the present embodiment, as described above, as the cam groove for the second group guide frame 21 of the cam frame 23, from the wide end rotation position toward the retracted rotation position, the −Z side. The cam groove 3c which is retreated by the distance L1 and is insufficient for the required movement amount is applied. As a result, the separation distance between the rear end surface of the first group frame 6 and the front surface portion of the second group guide frame 21 at the closest rotation position θ2P is larger than that when the cam groove 3c ′ is applied as shown in FIG. It will increase by L2. By increasing the separation distance at the time of the closest approach, the degree of freedom with respect to the arrangement and shape of the second group guide frame 21 including the first group frame 6 and the second group frame 23 increases, and the lens mirror sufficiently satisfies the optical system performance. A cylinder will be obtained.

  As described above, the cam groove 3c of the cam frame 23 is retracted by the distance L1 toward the -Z side from the retracted rotation position toward the wide end rotation position, and the second group guide frame 21 during zoom driving (therefore, accordingly) The amount of extension of the second group frame 21) is insufficient with respect to the required amount of movement, but this insufficient amount of movement is added to the amount of movement for focusing during the focusing drive process, and the second group frame 21 is aligned. It is driven by focus.

  Incidentally, the shape giving the peak of the cam groove 3c2 has a shape parallel to the peak shape of the cam groove 3c2 'giving the necessary optical movement amount (inclination angle is equal). By adopting the shape, the deviation amount of the extension amount of the second group guide frame 21 due to the variation of the stop rotation position at the time of zoom driving of the cam frame 3 is the deviation amount at the cam groove portion 3c2 ′ that gives the necessary optical movement amount. It can be about the same.

The focusing drive processing operation will be specifically described based on the flowchart of FIG.
By operating the zoom switch 94 during shooting, the cam frame 3 is rotated, and the first group frame 6, the second group guide frame 21, and the third group frame 8 are advanced and retracted by the female helicoid 3b and the cam grooves 3c and 3d. A desired zoom state is set. Therefore, when the first stage operation of the release switch 95 is performed, a subroutine “focus driving process” shown in FIG. 12 is incorporated in the CPU 91 in the main routine of the photographing sequence process executed under the control of the CPU 91. Executed by the control means.

  First, in step S01, the rotation position of the cam frame 3 in the zoom state is detected by the output of the zoom encoder 89, and it is checked whether the zooming position of the second lens group 12 which is the focusing lens group is within the normal region. To do. Whether or not the zooming position of the second group lens 12 is within the normal region is determined by whether the cam follower 15 that gives the zoom position of the second group guide frame 21 is the aforementioned bending point on the cam groove 3c of the cam frame 3 or not. Wide end rotation position than the turning point rotation angle position θ2F, which is in the range from the rotation angle position θ2F to the tele end rotation angle position θ2F, or the range where the required optical movement amount of zoom movement is insufficient Whether it is on the side of θ2W is determined (FIGS. 9 and 10).

  If it is determined in step S01 that it is within the normal region, the optically required movement amount is not insufficient, so that the addition of the zoom movement amount is unnecessary, and the process proceeds to step S02. If it is determined that the position is outside the normal region, the amount of zoom movement needs to be added because the required optical movement amount is insufficient, and the process proceeds to step S06.

  When the process proceeds to step S02, the focus drive position data stored in the RAM 97 based on the output data of the distance measuring means 99 is read and set as the drive amount at the time of focus drive from the normal zoom position.

  When the process proceeds to step S06, the amount of deviation from the zoom normal cam position corresponding to the rotation position of the cam frame 3 between the wide end rotation position θ2W and the bending point rotation angle position θ2F detected in step S01. Specifically, the RAM 97 reads movement amount data (deviation amount) in which the movement amount on the cam groove portion 3c1 or 3c2 is insufficient with respect to the movement amount on the cam groove portion 3c2 ′ that gives the optically required movement amount for zooming. On the other hand, the focus drive position data stored in the RAM 97 based on the output data of the distance measuring means 99 is read out, and both movement amount data are added and set as the drive amount at the time of focus drive.

  In step S03, driving of the focus motor 41 is started, and the second group frame 23 is driven back and forth. In step S04, whether the driving for the driving amount at the focusing driving set in step S06 is completed is checked by the output of the focus encoder 60, and if the driving completion is detected, the process proceeds to step S05. Then, the focus motor 41 is stopped, and this subroutine is finished.

  As described above, according to the lens barrel 110 of the present mounting form, the cam groove portions 3c1, 3c2, 3c3 between the wide end rotation position and the retracted rotation position in the cam groove 3c of the cam frame 3 are connected to the regular optical. By shifting the peak point downward with respect to the cam groove 3c ′ giving the necessary movement amount, the first group frame 6 and the second group guide frame 21 are retracted from the wide end position to the retracted position at the time of closest approach. Increased the separation distance. Therefore, the space occupied in the direction of the optical axis O between the first group frame 6 and the second group guide frame 21 can be made wider, the degree of freedom in arrangement and shape is increased, and the lens barrel has satisfactory optical performance. Furthermore, the lens barrel and camera can be miniaturized.

  In the lens barrel 110 of the present embodiment, when the zoom drive is performed near the wide end as described above, the amount of movement of the second group guide frame 21 (second group frame 23) is insufficient before the focus drive. However, since the camera 100 to which the lens barrel 110 is attached has the zoom optical viewfinder as described above, there is no problem in observing the viewfinder image.

  The shape of the cam groove 3c of the cam frame 3 of the lens barrel 110 of the mounting form described above is such that the peak cam groove 3c2 is formed on the retracted side of the wide end rotation position θ2W as shown in FIG. As a modified example of this shape, a cam frame 83 having a flat cam groove as shown in the enlarged view of the cam groove in FIG. 13 can be proposed.

  The cam frame 83 of this modification has a cam groove 83c that drives the second group frame 23 forward and backward as shown in FIG. 13. This cam groove 3c is located near the wide end rotation position θ2W, that is, the bending point. A cam groove portion 83c1 along the direction perpendicular to the optical axis O, that is, along the circumferential direction, in the range from the rotation drive position θ2F to the closest approach rotation position θ2P, and tilted toward the retracted position following the cam groove portion. It has a cam groove 83c3 and a cam groove from the bending point rotation drive position θ2F to the tele end. Since the cam groove portion 83c1 has no peak point, the shortage amount further increases with respect to the cam groove portion 3c2 'of the cam groove 3c' that gives a proper optically required movement amount during zoom driving. Therefore, when the cam follower 15 moves from the position corresponding to the wide end to the retracted position, the separation distance at the time of the closest approach between the first group frame 6 and the second group guide frame 21 becomes larger than that in the case of the cam groove of the mounting form. The degree of freedom of the arrangement shape of the first group frame 6 and the second group guide frame 21 is further increased.

  Even when the cam frame 83 of the present modification is applied, the focus drive processing operation shown in the flowchart of FIG. 12 is executed when the first stage of the release switch 95 is turned on, as in the case of the above embodiment.

  The lens barrel 110 to which the above-described embodiment or its modification is applied is applied to a camera having a zoom finder optical system, but is a single lens reflex camera not having a zoom finder optical system. It is possible to apply the structure of the above-described embodiment or its modification to the zoom lens barrel. However, when the cam frame 3 is between the wide end rotation position θ2W and the bending point rotation angle position θ2F, the correction of the deviation of the focusing lens group position from the zoom normal cam position is not zoom driving but focusing. It is necessary to correct the finder observation image to an observation image in a normal zoom state by correcting at the time of driving.

  A subroutine “focusing lens group correction driving process” for correcting the shift amount of the focusing lens group is shown in the flowchart of FIG. This correction driving process does not read out and add the driving amount for focusing with respect to the “focus driving process” shown in FIG. 12, and the focusing lens group (the second group lens of the second group frame 23). 12) is a process for performing only the position correction. In the focus drive process in this modification, a conventional focus drive process is executed.

  The structure of the lens barrel 110 can be applied not only to a silver salt camera but also to a lens barrel for a digital camera.

  A zoom lens barrel or a camera having a zoom lens according to the present invention has a zoom lens barrel or a zoom lens in which a frame member can be easily arranged, has a high degree of freedom in design, and can be downsized. It can be used as a camera.

1 is a perspective view showing an appearance of a zoom lens barrel that is an embodiment of the present invention. FIG. It is sectional drawing along the imaging | photography optical axis in the lens barrel retracted state of the silver salt camera with which the zoom lens barrel of FIG. 1 is mounted | worn. FIG. 2 is a cross-sectional view taken along a photographing optical axis in a wide state where the zoom lens barrel of FIG. 1 can be photographed. 1 is a cross-sectional view along the imaging optical axis in a telephoto state in which the zoom lens barrel can be imaged. FIG. 2 shows a part of an exploded perspective view of the zoom lens barrel of FIG. 1. The other part of exploded perspective view of the zoom lens barrel of FIG. 1 is shown. FIG. 2 is an exploded perspective view of a focus unit built in the zoom lens barrel of FIG. 1. FIG. 8 is a cross-sectional view around the feed shaft portion that constitutes the focusing drive mechanism portion of the focus unit, as viewed from the arrow E in FIG. 7. FIG. 2 is a development view showing shapes of a female helicoid and a cam groove in an inner peripheral portion of a cam frame applied to the zoom lens barrel of FIG. 1. FIG. 10 is an enlarged view of a P-part cam groove of FIG. 9 and shows a detailed shape of the cam groove. It is a block block diagram of the electric circuit of the camera of FIG. 3 is a flowchart of a focus drive process called in a main routine of a shooting sequence in the camera of FIG. FIG. 7 is an enlarged view of a cam groove of a modification example with respect to the cam groove in the cam frame of the zoom lens barrel of FIG. 1. 7 is a flowchart of a subroutine “Focusing lens group correction driving process” in a modification in which the zoom lens barrel of FIG. 1 is applied as a zoom lens barrel of a single-lens reflex camera. It is the elements on larger scale of the frame member of the conventional zoom lens barrel.

Explanation of symbols

3c ... Cam groove (zoom cam)
3c1, 3c2
... Cam groove (cam streaks that are insufficient for the required optical travel,
Zoom cam muscle)
3c3 ... Cam groove (collapse cam)
11: First lens group (multiple lens groups, other lens groups)
12. Second lens group (Multiple lens group, Focusing lens group)
13 ... Third lens group (plural lens groups)
23k, 23m
... Back projection (focus drive mechanism)
50 ... Feed screw (focusing drive mechanism)
52 ... Drive nut (focus drive mechanism)
91 ... CPU (control means)

Agent Patent Attorney Susumu Ito

Claims (1)

In a camera with a zoom lens that retracts,
A focusing lens group for focusing among a plurality of lens groups constituting the zoom lens;
A cam for advancing and retreating the focusing lens group in the optical axis direction for zooming, and the amount of movement necessary to avoid interference with the focusing lens group between the wide end rotation position and the retracted rotation position is light. a cam having a zoom cam muscle is insufficient to optical required amount of movement for performing a retracting cam muscle zooming leads to a shortage in the axial direction,
A focusing drive mechanism for driving the focusing lens group for focusing;
To function the focus drive mechanism, when focusing the focusing lens groups, by adding the movement shortage amount of the focusing lens unit caused by the <br/> zoom cam muscle movement amount for focusing Control means for controlling the focusing drive mechanism so as to move the focusing lens group;
A camera having a zoom lens.

Images