Abstract: A zoom lens barrel includes a cylindrical member which is provided with a female helicoid; a split helicoid cylinder having a rear helicoid ring portion which is provided with a male helicoid which is screw-engaged with the female helicoid, and a front cylindrical portion which is detachably connected to the rear helicoid ring portion so as not to relatively rotate; a linear movement cylinder provided in the split helicoid cylinder so as to move in the optical axis direction; and a connecting structure for connecting the linear movement cylinder to the split helicoid cylinder so as to relatively rotate and so as not to relatively move in the optical axis direction, so that the rear helicoid ring portion and the front cylindrical portion of the split helicoid cylinder maintain connected by the connecting structure without being disconnected in the optical axis direction.

Abstract: An engagement structure for cylindrical members includes a first cylindrical member including a plurality of engagement projection portions of different shapes having the same projecting length in the radial direction, and a second cylindrical member including a plurality of groove portions corresponding to the engagement projection portions, each the groove portions having at least one groove, wherein one of the first and second cylindrical members is accommodated inside the other of the first and second cylindrical members. The engagement projection portions and the corresponding groove portions can be engaged and disengaged only at one relative circumferential position of the first and second cylindrical members, and at a relative circumferential position other than the one relative circumferential position, the engagement projection portions of the first cylindrical member are always engaged with at least a portion of the groove portions other than the grooves thereof.

Abstract: A movement of an optical axis of a photographing optical system due to a focused image tremble is detected as a displacement on a focal plane. An object image is formed on the focal plane by the photographing optical system, and when an optical axis of a correction lens is coaxial with an optical axis of other optical systems included in the photographing optical system, the optical axis of the photographing optical system pierces through a center of the focal plane. On the focal plane, a correctable range of the correction lens is defined based on a structure of a correction device. An original point of the correctable range is the center of the focal plane. If a focused image tremble occurs out of the correctable range, an intersection of a boundary of the correctable range and a straight line connecting a position of the optical axis of the photographing optical system and the original point is calculated.

Abstract: A zoom lens barrel includes a first cylindrical member having first and second bottomed grooves, which intersect each other, on an inner peripheral surface thereof; a first moving member which is provided with a first radial projection which is fitted in the first bottomed groove, the first moving member being movable relative to the first cylindrical member; and a second moving member which is provided with a second radial projection which is fitted in the second bottomed groove, the second moving member being movable relative to the first cylindrical member. The shapes of the first bottomed groove and the first radial projection and the shapes of the second bottomed groove and the second radial projection are such that the second radial projection cannot be fitted in the first bottomed groove and that the first radial projection cannot be fitted in the second bottomed groove.

Abstract: A zoom lens barrel includes a rotary feed cylinder which is moved in an optical axis direction while being rotated; a linear movement cylinder which is provided within the rotary feed cylinder; and a connecting structure for connecting the linear movement cylinder to the rotary feed cylinder. The connecting structure includes at least two circumferential grooves centered about the optical axis, provided on the inner peripheral surface of the rotary feed cylinder or the outer peripheral surface of the linear movement cylinder, at different positions in the optical axis direction; and at least two radially extending engagement pawls which correspond to the at least two circumferential grooves, the engagement pawls being engaged in the circumferential grooves so as to slide in the circumferential direction and so as not to relatively move in the optical axis direction.

Abstract: An eccentricity-prevention mechanism includes a pair of lens-supporting rings for supporting a pair of lens groups, respectively; and a pair of positioning recesses and a follower projection formed on one and the other of opposed surfaces of the pair of lens-supporting rings, such that the follower projection engages with one of the pair of positioning recess to define a relative position of the pair of lens-supporting rings with respect to the optical axis, at a mutually close position and at a mutually distant position. At least three pairs of the positioning recesses and at least three follower projections are provided at different positions in a circumferential direction, so that eccentricity between the pair of lens-supporting rings is eliminated when all of the follower projections are concurrently brought into engagement with corresponding positioning recesses.

Abstract: A lens barrel includes a lens frame, for supporting a photographing lens group, which have guide bore which extends in a direction parallel to the optical axis; a support barrel including front and rear rod support portions which face each other, with the guide bore provided therebetween; guide rod supported by the front and rear rod support portions by the front and rear ends thereof, respectively, the guide rod being placed through the guide bore and guiding the lens frame to move relative to the support barrel in the optical axis direction; and a coil spring for biasing the lens frame in an optical axis direction, the coil spring provided around the guide rod so as to be positioned between the lens frame and one of the front rod support portion and the rear rod support portion.

Abstract: A zoom lens mechanism includes a switching lens group frame which supports a first sub-lens group frame and a second sub-lens group frame; a shift cam mechanism provided on opposed surfaces of the first and second sub-lens group frames, respectively, the shift cam mechanism causing the first and second sub-lens group frames to move to a mutually close position or mutually distant position; an actuator ring for providing relative rotation between the first and second sub-lens group frames; a receiving surface provided on the switching lens group frame wherein a rear end surface of the actuator ring abuts against the receiving surface; and a biasing device for biasing the first sub-lens group frame toward the actuator ring to force the first and second sub-lens group frames, and the actuator ring against the receiving surface, so that the shift cam mechanism come into contact with each other.

Abstract: A zoom lens mechanism includes a switching lens group frame supporting a first sub-lens group frame and a second sub-lens group frame which support first and second sub-sub-lens groups, respectively; a lens group shift mechanism for causing the first and second sub-lens group frames to linearly move to a mutually close position or a mutually distant position, with respect to the optical axis direction, in accordance with relative rotation between the first sub-lens group frame and the second sub-lens group frame; and a focusing mechanism which integrally moves the first sub-lens group frame and the second sub-lens group frame in the optical axis direction while maintaining a distance therebetween after the first and the second sub-lens group frames are moved to one of the mutually close position and the mutually distant position by the lens group shift mechanism.

Abstract: A lens barrel having a zoom lens system including variable power lens groups, at least one of which includes a switching lens group having two sub-lens groups, the lens barrel includes a first sub-lens group frame for supporting one of the sub-lens groups; a second sub-lens group frame for supporting the other sub-lens group; a switching lens group frame for supporting the first and second sub-lens group frames; a lens shutter mechanism secured to the switching lens group frame on the image side of the second sub-lens group frame; and a focusing mechanism for making the second sub-lens group frame advance or retreat, with respect to a reference position provided by the lens shutter mechanism secured to the switching lens group frame. The first and second sub-lens group frames are integrally moved along in the optical axis direction via the focusing mechanism.

Abstract: A reduction gear mechanism includes at least first and second axes which extend parallel to each other; one of the first and second axes rotatably supports at least two gears arranged one after the other in the axial direction thereof, and the other of the first and second axes rotatably supports at least one gear, and the gears provided on the first and second axes being engaged with each other in such a manner that the gear supported on one of the first and second axes successively and alternatively engages with the gear supported on the other of the first and second axes.

Abstract: A shift mechanism includes first and second ring bodies which are relatively rotatable; a shift cam surface formed on the first ring body on an end surface thereof which faces the second ring body, the shift cam surface being inclined with respect to a circumferential direction of the first ring body; a follower projection formed on the second ring body for engaging with the shift cam surface; and a rotating mechanism for relatively rotating the first and second ring bodies. The shift cam surface and the follower projection are arranged to move the first and second ring bodies toward and away from each other in the axial direction as the first and second ring bodies are relatively rotated. An annular rib is formed along the circumference of the first ring body outside the shift cam surface over the follower projection of the second ring body.

Abstract: A lens barrel includes front and rear sub-lens groups; front and rear sub-lens group frames for supporting the front and rear sub-lens groups, respectively; a lens frame shift mechanism for causing the front sub-lens group frame and the rear sub-lens group frame to move relative to each other to obtain the mutually close position and the mutually distant position; a first lens group positioning surface provided on the front sub-lens group frame for positioning the front sub-lens group by contacting with a portion of a rear surface of the front sub-lens group; and a second lens group positioning surface provided on the rear sub-lens group frame for positioning the front sub-lens group by contacting with a portion of a front surface of the rear sub-lens group.

Abstract: A lens barrel includes a lens frame for supporting a photographing lens group, the lens frame including a guide bore which extends in a direction parallel to the optical axis; a support barrel, wherein the lens frame can be inserted into and removed from a front opening of the support barrel; a rod receiving portion formed inside the support barrel; a bracket detachably attached to a front end of the support barrel; and a guide rod provided on the bracket for guiding the lens frame to move relative to the support barrel in the optical axis direction, the guide rod engaging with the rod receiving portion when the bracket is attached to the support barrel. The lens group frame can be taken out of the support barrel through the front opening when the bracket having the guide rods is removed from the support barrel.

Abstract: A lens drive mechanism includes first and second sub-lens group frames for supporting first and second sub-lens groups; a support frame for supporting the first and second sub-lens group frames; a first linear guide mechanism which linearly guides the first sub-lens group frame and prevents rotation thereof; a second linear guide mechanism which linearly guides the second sub-lens group frame, while limiting rotation thereof, at two extremities of rotation thereof; a lens frame shift mechanism for causing the first and second sub-lens group frames to move to the mutually close or distant position; and a linear displacement mechanism which integrally moves the first and second sub-lens group frames in the optical axis direction, in the mutually close or distant position. A linear guide clearance of the first linear guide mechanism is larger than a linear guide clearance of the second linear guide mechanism.

Abstract: A wiring structure of an image stabilizer includes a movable member which supports an image-stabilizing optical system, a cylindrical base which supports the movable member, a first drive device which drives the movable member in a first direction, a second drive device which drives the movable member in a second direction, first and second electrical elements associated with the first and drive devices, respectively, and a flexible printed wiring board which has one end positioned inside the cylindrical base and is provided with first and second wiring strips which firstly extend in opposite directions away from each other along the circumferential direction about the optical axis, and subsequently fold back inwardly towards each folded portion of each respective second and first wiring strips, to be connected with first and second electrical elements, respectively, after intersecting each other as viewed along the optical axis.

Abstract: In an image-tremble-correcting system for an optical instrument, having an optical focussing system for producing a focussed image, to correct a tremble of the focussed image caused by an oscillation of the optical instrument, a movable optical tremble-correction system is assembled in the focussing system of the optical instrument. An X-Y rectangular coordinate system which is defined on a plane perpendicular to the optical axis of the focussing system, the origin of the coordinate system coinciding with the optical axis of the focussing system, the X- and Y-axes thereof defining an angle of 45° with a horizontal axis and a vertical axis defined on the plane when the optical instrument is positioned at a usual attitude. The movable optical tremble-correction system being movable along the X-axis and the Y-axis of the X-Y rectangular coordinate system to the same extent.

Abstract: A focal length detector of a camera having a zoom lens includes a brush having three sliding contacts which are electrically connected to one another; a code plate having three code patterns and a ground pattern, the code plate and the brush being moved relative to each other according to a variation of the focal length of the zoom lens; and a focal-length detecting circuit which is connected to the three code patterns and the ground pattern. The ground pattern always contacts a specific sliding contact of the three sliding contacts. The three code patterns are arranged so that the three code patterns come into contact with the remaining two sliding contacts in predetermined combinations when the code plate and the brush are moved relative to each other.

Abstract: An inner barrel includes a male helicoid, and an outer barrel includes a female helicoid which can engage with the male helicoid of the inner barrel. The included angle of trapezoidal threads of the male helicoid are identical to an included angle of trapezoidal grooves of the female helicoid in a section perpendicular to a direction of an extension of the threads.

Abstract: A zoom lens barrel includes a stationary barrel; a first rotational feed barrel which is engaged with the stationary barrel by means of helicoids; a first linear movement barrel which is engaged with the first rotational feed barrel so as to relatively rotate and to relatively move together along the optical axis and which is provided on the inner peripheral surface thereof with a female helicoid; a second rotational feed barrel which has a male helicoid and a female helicoid on the outer and inner peripheral surfaces thereof respectively; a rotational transmission barrel which is engaged with the first rotational feed barrel so as to relatively move along the optical axis and to rotate together, and which is integrally connected to the second rotational feed barrel; a second linear movement barrel which is provided on outer peripheral surface thereof with a male helicoid which engages with the female helicoid of the second rotational feed barrel; a lens group that is held by said second rotational feed barre