Abstract: A lens barrel includes a stationary barrel, first through third lens support rings, and a lens drive ring including a first guide engaged with a guide formed on the stationary barrel; an engaging portion engaged with a guide formed on the first lens support ring, the lens drive ring and the first lens support ring being relatively rotatable and integrally movable in the optical axis direction; a second guide, engaged with a guide formed on the second lens support ring, to move the second lens support ring in the optical axis direction relative to the lens drive ring via rotation of the lens drive ring; and a third guide engaged with a guide formed on the third lens support ring to move the third lens support ring in the optical axis direction relative to the lens drive ring via rotation of the lens drive ring.

Abstract: A projection lens unit is provided that is reduced in size and profile. The projection lens unit may include a plurality of lenses of which at least one lens disposed at the base end opposite to the projection direction is cut away at the upper portion thereof. The surface of the cut-away portion of the lens is made flat. With this arrangement, a space above the lens can be used when a cooling fan is disposed above an electrooptical unit provided in the vicinity of the projection lens unit, whereby a projector can be reduced in size and profile, because the height of the projector can be reduced because it is not necessary to provide an additional space for receiving the cooling fan in the projector.

Abstract: The present invention is an inexpensive and accurate means of improving resolution when imaging a small digital display onto a larger photosensitive medium. The device includes a printer having a housing that encloses, in a common cavity thereof, an arrangement comprising a digital area array display, a plurality of lenses, and an image plane. The digital area array display, the plurality of lenses, and the image plane are spaced along an optical axis extending from the digital area array display through the plurality of lenses, and toward the image plane such that a digital image provided by the display can be brought into focus onto the imaging plane by the plurality of lenses. One of the plurality of lenses is a transposable lens, the transposable lens capable of being transposed out of the optical axis during the operation of the printer, to increase the perceived resolution of the digital image focused onto the imaging plane.

Abstract: A body of a lens frame, which is a lens barrel of the present invention, consists of an inner frame for holding a lens, an intermediate frame in which an adjusting screw is screwed, and an outer frame in which an adjusting screw is screwed. The frames are connected to one another by parallel springs. In the case of this lens frame, the inner frame is displaced in the direction of X-axis or a horizontal axis by screwing the adjusting screw thereinto in the direction of the horizontal axis and screwing another adjusting screw thereinto by the direction of a vertical axis. Thus, the inner frame is displaced in Y-direction through the intermediate frames. Consequently, the translation of the position of the optical axis of the lens is performed without inclination of the intermediate frame. Hence, the adjustment of the position of the optical axis is easily achieved. Moreover, this lens frame achieves a reduction in the cost of components thereof.

Abstract: A lens driving apparatus which drives a first and a second lens group arranged in the optical axis by a first drive means and a second drive means, wherein the apparatus has a first and a second cam followers extending mutually parallel in a right angle direction to the optical axis from the first and second lens groups and cam member having first and second cams arranged along the optical axis and respectively engaging the first and second cam followers.

Abstract: A lens position control apparatus is disclosed which comprises a variable power lens unit that moves along the optical axis; a focussing lens unit; a drive unit for driving the variable power lens unit along the optical axis; a member defining the reference position to be used prior to execution of a focussing operation of the focussing lens unit, the member being movable along the optical axis in accordance with the movement of the variable lens unit; and calculating means for calculating the driven amount of the focussing lens unit from the reference position in association with the focussing operation thereof, wherein the focus lens is moved to the reference position first, and then driven again based on the distance moved.

Abstract: There is provided an optical device which comprises a fixed barrel, a movable cam ring, and collars and abutments. The movable cam ring is shifted relative to the fixed barrel to move an optical unit, the movable cam ring being fitted to the fixed barrel. Collars and abutments can be engaged with each other when the movable cam ring is in a predetermined positional relationship with respect to the fixed barrel. The collars and abutments preventing the movable cam ring from being disengaged from the fixed barrel and displaced in a direction along an optical axis relative to the fixed barrel.

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 having a zoom lens system including a plurality of variable power lens groups which includes a switching lens group having two sub-lens groups which are optically operable in mutually close and distant positions, the lens barrel includes a first sub-lens group frame for supporting one sub-lens group; 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 shift mechanism for selectively moving the first and second sub-lens group frames in the switching lens group frame to the mutually close and distant positions; and a switching lens group frame moving mechanism for moving the switching lens group frame with the other variable power lens group(s) along a predetermined path to vary the focal length; wherein combined movement of the shift mechanism and the switching lens group frame moving mechanism provides a zoom path for the sub-lens groups.

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 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 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 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 zoom viewfinder includes an objective optical system having a frontmost lens group and a movable lens group positioned behind the frontmost lens group, and a guide shaft which extends parallel to an optical axis of the objective optical system to guide the movable lens group in the optical axis direction. The frontmost end of the guide shaft is positioned behind the frontmost lens group of the objective optical system.

Abstract: A step zoom lens camera having a zoom lens and a cam ring provided with a cam groove having step portions. The zoom lens camera includes a focusing lens group which serves also as a variable power lens group of the zoom lens; and an adjusting lens group, serving also as another variable power lens group of the zoom lens, which is guided by the cam groove and is moved in the optical axis direction in a non-linear relationship with respect to the rotation angle of the cam ring in each focal length step. The step portions of the cam groove are each provided with a path which enables the adjusting lens group to move so as to provide a linear relationship between the rotation angle of the cam ring and amount of movement of the focal position of an infinite distance object.

Abstract: A camera having a manually operated zoom lens system, in which the magnification of the lens system is adjusted by manual rotation of a part of the lens systems. The camera includes a lens system having at least first and second optical elements, the first optical element being movable relative to the second optical element, a mechanism for moving the first optical element relative to the second optical element, and a rotatable element for operating the mechanism to change the magnification of the lens system. The camera further includes a view finder with adjustable magnification for providing a view representative of the image captured by the lens systems. The view finder includes first and second optical elements, the first element being moveable relative to the second element to change the magnification of the view finder and a mechanism for moving the first optical element relative to the second element.

Abstract: In a zoom lens device of the present invention, an aperture at a predetermined zooming step that is other than a telephoto end and a wide-angle end is smaller than apertures at the other zooming steps, and the predetermined zooming step is used only when a macro shooting mode is chosen. In the present invention, the predetermined zooming step between the telephoto end and the wide-angle end is set only for the macro shooting mode, and the aperture in the macro shooting mode is small enough to make the field depth large. Therefore, the simple and inexpensive lens device can perform the macro shooting.

Abstract: A lens moving device comprises a cam follower which is provided to a lens holding frame supporting a lens, and a cam gear with which the cam follower is engaged. The cam gear is rotated by a stepping motor, so that the lens holding frame and the lens move along the optical axis thereof. The cam gear is molded from synthetic resin and is provided with a stopper at the both ends of a non-operative area, in which the cam follower does not come in contact during a normal operation. The non-operative area has a gate mark, which is formed during the resin molding process. The stopper prevents the cam follower from interfering with the gate mark.

Abstract: A combinational object lens 3 constructed of a first lens 1 and a second lens 2 is formed. The first lens 1 and a first lens barrel 4 for retaining the first lens 1 are fixed by bonding to a second lens barrel 5 for retaining the second lens 2 only via a spacer layer 7 made of an adhesive. With this arrangement, residual aberration of the combinational object lens constructed of a plurality of lenses can be reduced, and this further enables the compacting and reduction in weight of the object lens barrels, an object lens barrel drive unit and an optical information recording and reproducing unit.

Abstract: An optical element holding device includes a ring body for accommodating an optical element and a drive mechanism for driving the optical element. The ring body has an inner ring portion, which engages with a peripheral edge of the optical element, and an outer ring portion integral with the inner ring portion. The drive mechanism includes an actuator, a displacement increasing mechanism and a guide mechanism. The guide mechanism transfers displacement of the actuator to the inner ring and moves the inner ring axially.

Abstract: A lens barrel comprises first and second cylinders, a base, a single motor, a feed screw, a rotation mechanism, a helicoid mechanism, and a drive gear for transmit a drive force of the motor to the feed screw and the rotation mechanism. The drive gear comprises a cylindrical gear and a shaft gear having a shaft inserted in the cylindrical gear. The cylindrical gear and the shaft gear rotating about a common rotation axis. The cylindrical gear is interposed between the rotation mechanism and the motor, and the shaft gear is interposed between the feed screw and the motor. Accordingly, zooming and focusing can be made by one motor, increasing density and integration and providing excellent space efficiency.

Abstract: A lens barrel includes a lens movable in a direction orthogonal to the optical axis of the lens barrel, a movable member that holds the lens, a fixed member that regulates movement of the movable member in a direction of the optical axis, at least three balls placed between the movable member and the fixed member, each of the balls being held in a holding portion formed in one of the movable member and the fixed member so as to roll and to allow relative movement between the movable member and the fixed member, an urging member that urges the movable member toward the fixed member, a driving unit that generates force for moving the movable member in two directions orthogonal to the optical axis, and a position detecting mechanism for detecting positions of the movable member in the two directions orthogonal to the optical axis.

Abstract: A body of a lens frame, which is a lens barrel of the present invention, consists of an inner frame for holding a lens, an intermediate frame in which an adjusting screw is screwed, and an outer frame in which an adjusting screw is screwed. The frames are connected to one another by parallel springs. In the case of this lens frame, the inner frame is displaced in the direction of X-axis or a horizontal axis by screwing the adjusting screw thereinto in the direction of the horizontal axis and screwing another adjusting screw thereinto by the direction of a vertical axis. Thus, the inner frame is displaced in Y-direction through the intermediate frames. Consequently, the translation of the position of the optical axis of the lens is performed without inclination of the intermediate frame. Hence, the adjustment of the position of the optical axis is easily achieved. Moreover, this lens frame achieves a reduction in the cost of components thereof.

Abstract: A lens barrel includes fixed tubes each arranged to hold an optical unit having an optical axis, a rotating tube arranged to rotate around the optical axis with respect to the fixed tubes, wherein the rotating tube is provided, at front and rear portions thereof as viewed along the optical axis, respectively with end surfaces of ring shape having a center thereof on the optical axis, and each of the fixed tubes is provided with an end surface opposite to the associated end surface of the rotating tube, and sheet members of ring shape having a center thereof on the optical axis, each of the sheet members being disposed on a space formed by each end surface of the rotating tube and the associated end surface of the fixed tubes, so that the torque of a rotating operation on the rotating tube is lessened and, yet, the lens barrel excels in dust-proof and drip-proof.

Abstract: A lens barrel comprises first and second tubes, a base, a single motor, and a drive gear for transmitting a drive force of the motor to the first and second tubes. The drive gear comprises a cylindrical gear and a shaft gear having a shaft inserted in the cylindrical gear. The cylindrical gear and the shaft gear rotating about a common rotation axis. The cylindrical gear is interposed between a first feed screw and the motor, and the shaft gear is interposed between a second feed screw and the motor. Accordingly, zooming and focusing can be made by one motor, increasing density and integration and providing excellent space efficiency.

Abstract: A focuser having a drawtube on which an eyepiece can be mounted, a track secured to the drawtube, and a base adapted to be mounted to an optical tube of a telescope. The base is movably engaged with the drawtube such that the drawtube and track are able to move relative to the base along an optical axis. A shaft is rotatably secured to the base and operatively engaged with the track such that rotation of the shaft effects movement of the drawtube relative to the base. This, in turn, results in relative movement between the eyepiece and optical tube along the optical axis, so as to focus the telescope. The drawtube, track and base are configured such that the base applies a first force to the drawtube and a second opposing force to the track to align the drawtube and track as they move along the optical axis.

Abstract: A movable lens hood mechanism of a zoom lens includes a plurality of lens groups guided linearly in a direction of an optical axis to change a focal length of the zoom lens; a first cam barrel rotatably driven to move the plurality of lens groups in the optical axis direction; a movable hood barrel having a photographic aperture positioned in front of the frontmost lens group and guided linearly in the optical axis direction; and a feed mechanism which drives the movable hood barrel forward/rearward in the optical axis direction relative to the frontmost lens group by rotation of the first cam barrel so that a space between the photographic aperture of the movable lens hood and the frontmost lens group in the optical axis direction varies in accordance with a variation of a focal length of the zoom lens.

Abstract: A lens barrel includes an optical element having a light-transmissive surface which is deformed by own weight thereof and/or by being supported, and a plurality of protrusive parts which support the optical element. The plurality of protrusive parts are disposed in such a way as to enable the light-transmissive surface of the optical element to be deformed symmetrically with respect to a plane which includes an optical axis.

Abstract: A cam mechanism includes a linear guide barrel provided with a linear guide projection at one end thereof, extending radially outwards; a cam barrel fitted on the linear guide barrel, rotatable relative to the linear guide barrel and movable along the optical axis with the linear guide barrel, the cam barrel being provided with a cam groove on an inner surface thereof; a linear guide slot formed on the linear guide barrel extending parallel to the optical axis; at least one lens frame positioned inside the linear guide barrel; a projection formed on the lens frame to be slidably engaged in the linear guide slot; and a cam follower formed on the projection to be engaged in the cam groove. The linear guide projection and the linear guide slot are formed on the linear guide barrel at the same circumferential position of the linear guide barrel.

Abstract: A zoom lens includes a plurality of lens groups, and a cam barrel having a cam groove formed on an inner peripheral surface thereof. The cam barrel includes a first barrel having the cam groove on an inner peripheral surface thereof, and a second barrel which is fitted on a front part of an outer peripheral surface of the first barrel, the first barrel and second barrel being movable in the optical axis direction with a predetermined clearance provided therebetween in the optical axis direction while being rotatable together about the optical axis, so that an external force applied to the zoom lens from the outside of the zoom lens is transmitted to the first barrel via the second barrel.

Abstract: A body of a lens frame, which is a lens barrel of the present invention, consists of an inner frame for holding a lens, an intermediate frame in which an adjusting screw is screwed, and an outer frame in which an adjusting screw is screwed. The frames are connected to one another by parallel springs. In the case of this lens frame, the inner frame is displaced in the direction of X-axis or a horizontal axis by screwing the adjusting screw thereinto in the direction of the horizontal axis and screwing another adjusting screw thereinto by the direction of a vertical axis. Thus, the inner frame is displaced in Y-direction through the intermediate frames. Consequently, the translation of the position of the optical axis of the lens is performed without inclination of the intermediate frame. Hence, the adjustment of the position of the optical axis is easily achieved. Moreover, this lens frame achieves a reduction in the cost of components thereof.

Abstract: A floating lens barrel includes a stationary barrel which can be connected to a camera body, a rotation ring which is rotatably supported by the stationary barrel and which is rotated in accordance with the focusing operation, a female helicoid ring provided on the stationary barrel, a front lens support ring which supports a focusing front lens group and which is guided to move linearly in the optical axis direction, a male helicoid ring which is supported by the front lens support ring so as to rotate relative thereto but not to move in the optical axis direction relative to the front lens support ring, a combination of rotation transmission grooves and pins for transmitting the rotation of the rotation ring to the male helicoid ring, and a rear lens support ring which holds a focusing rear lens group and which is guided to move linearly in the optical axis direction by the front lens support ring, in accordance with a cam groove formed in the male helicoid ring.

Abstract: A zoom viewfinder device has a viewfinder body. Two movable lenses are accommodated in the viewfinder body. A lens moving mechanism drives the movable lenses in the viewfinder body. A rectilinear guiding mechanism guides movement of each movable lens in an optical axis direction thereof. In the rectilinear guiding mechanism, a rectilinear guiding groove is formed in the viewfinder body, extended in the optical axis direction. A follower projection is formed with a periphery of the movable lens, for contacting the rectilinear guiding groove to slide along the rectilinear guiding groove. A one-side positioning rod keeps the follower projection pressed on the rectilinear guiding groove by pushing the movable lens in a direction crosswise to the optical axis direction, for absorbing play of the movable lens relative to the optical axis direction.

Abstract: A specific lens with a high sensitivity to an eccentricity is selected from a lens optical system and is provided with a tilting mechanism, which enables the tilt angle of the lens to be adjusted from outside a lens barrel. After lenses are fitted into the lens barrel, the tilting mechanism enables the adjustment of a resolution while the image quality of the lens optical system is observed. A second lens frame for supporting a second lens, which has the greatest effect on the resolution in the lens optical system, is arranged inside a first lens frame. A reference pin and two eccentric pins are provided at regular intervals of 120 degrees on the circumferential surface of the first lens frame. The reference pin and two eccentric pins support the second lens frame from the outside. The pins are inserted into grooves formed in the second lens frame. A projecting part is formed at the outer circumference of the second lens frame, and the projecting part comes into contact with the first lens frame.

Abstract: A structure which holds a lens by fitting a lens holding member holding a lens into an outer cylindrical member. In the structure, a biasing mechanism is provided to bias the lens holding member, located within the outer cylindrical member, forward or backward in an optical axis direction. A plurality of engaging nails are arranged on one of circumferential surfaces of the lens holding member and the outer cylindrical member at substantially equal angular intervals circumferentially. A plurality of fixing holes arranged on the other of the circumferential surfaces of the lens holding member and the outer cylindrical member at substantially equal angular intervals circumferentially to be respectively engaged with the engaging nails to retain the lens holding member relative to the outer cylindrical member against a biasing force of the biasing mechanism.

Abstract: A zoom lens is formed of a fixed cylinder, an outer movable cylinder, an inner movable cylinder, and a guide plate disposed between the fixed cylinder and the outer movable cylinder. The outer movable cylinder is movably fitted into the fixed cylinder and is provided at one end thereof with a first locating point, a second locating point, and a third locating point. The guide plate displaces along with the outer movable cylinder and has a reference portion, which is aligned with the first locating point, the second locating point, and the third locating point to determine the focal position of the lens.

Abstract: Disclosed is an engaging structure of two cylindrical members. At least part of one of the two cylindrical members is coaxially fitted on the other cylindrical member. The engaging structure includes: a plurality of radial projections formed on the second cylindrical member; two annular flanges formed on the other cylindrical member to form a circumferential groove therebetween, the plurality of radial projections being fitted in the circumferential groove; and a plurality of cut-away portions, formed on one of the two annular flanges, through which the plurality of radial projections are respectively inserted into the circumferential groove. Each corresponding pair of the plurality of projections and the plurality of cut-away portions are formed to have a circumferential width different from those of the other corresponding pairs of the plurality of projections and the plurality of cut-away portions.

Abstract: The invention relates to an arrangement with optical elements, in which a first housing portion with optical elements is releasably held to a second housing portion with optical elements. A magnetic holding device is installed between the first housing portion and the second housing portion to releasably hold the first housing portion to the second housing portion.

Abstract: A helicoid is formed at the outer periphery of the front of a body fixing lens barrel, and a helicoid is formed at the inner periphery of the back of the focusing lens barrel in such a manner that these two helicoids can be engaged with each other. A movable focusing lens group is held by the front of the focusing lens barrel so that the helicoid can be pushed to one side and the inaccurateness of the focus can be reduced. A lens hood is attached to a fixed focus lens frame fixed to a focus fixing lens barrel, which is different from the body fixing lens barrel. Thereby, even if the focus fixing lens barrel is deformed by the force generated by the attachment, the deformation does not warp the helicoid.

Abstract: A lens barrel includes a lens holding barrel holding a lens, a containing barrel containing the lens holding barrel therein, a plurality of inwardly directed projections provided on the inner peripheral surface of the containing barrel, and a plurality of groups of outwardly directed projections provided on the outer peripheral surface of the lens holding barrel, each of the plurality of groups of outwardly directed projections having the same number of outwardly directed projections as the number of the inwardly directed projections, the plurality of inwardly directed projections bearing against respective ones of the outwardly directed projections in one group at a time to position the optical axis to the lens, virtual circles circumscribed on the outwardly directed projections in the respective groups having the same size in a plane perpendicular to the optical axis, the centers of the virtual circles lying at different positions.

Abstract: A lens assembly is disclosed in which the amount of movement of at least one lens unit is achieved by combining the amounts of relative movement of at least two barrels. A linear advancement barrel advances straight ahead relative to a fixed barrel. A first lens unit moves together with the linear advancement barrel. A second lens unit is located in front of the first lens unit along the optical axis. A third lens unit is located behind the first lens unit along the optical axis. A cam ring moves together with the linear advancement barrel along the optical axis and rotates around the optical axis. The cam ring has first and second cams that move the second lens unit and the third lens unit by amounts of movement relative to the linear advancement barrel.

Abstract: A lens barrel having first and second lens groups and first and second tubes. The first tube has first and second guide grooves to respectively guide the first and second groups in an optical direction. The second tube has first and second cam grooves to respectively guide the first and second lens groups, in conjunction with the first and second guide grooves, for focusing and zooming operations. A first collapsing use groove extends substantially perpendicular to the optical axis from an end of the second guide groove that is closer to an image surface to maintain the second lens group in a stationary position on the optical axis when the first lens group is collapsed toward the second lens group and when the first lens group is extended into a wide state.

Abstract: A lens apparatus, such as a lens barrel for a camera, allows different optical systems to be easily removed and installed. The lens apparatus has first and second optical systems with an optical axis of the lens apparatus extending thorough the first and second optical systems. First and second lens compartments respectively retain the first and second optical systems. First and second lens frames respectively correspond to, and respectively retain, the first and second lens compartments. The first and second lens compartments are independent structures from the first and second lens frames to allow the first and second lens compartments to be removed from, and inserted into, the respectively corresponding first and second lens frames. The present invention also relates to a method of assembling the lens apparatus.

Abstract: The projection-lens driving apparatus for a 3-beam projector includes a housing, a triplet of cylindrical projection-lens holders, a pair of cam members, each of the cam members having a triplet of guide rails, a trifurcating member, a driving means provided with a feed screw and a motor, three pairs of brackets, three pairs of feed rollers, one end of each of the brackets coupled to one of the feed rollers which, in turn, is coupled to one of the guide rails, the other end thereof being coupled to one cylindrical projection-lens holder, and a triplet of guiding means, each of the guiding means mechanically coupling one of the cylindrical projection-lens holders with the housing. The pair of cam members and the cylindrical projection-lens holders are mechanically coupled through the feed screw of the driving means to allow a synchronous movement of the components constituting the apparatus.

Abstract: A zoom lens assembly includes a stationary lens barrel and a rotatable cam ring which is supported on the stationary lens barrel for movement in the direction of the optical axis while being rotated, and which includes at least two cam grooves. The zoom lens include first and third lens groups which are both moveable by one of the two cam grooves in the direction of the optical axis. A second lens group movable, by a second of the two cam grooves in the direction of the optical axis is also provided, as well as a focusing mechanism, for moving the second lens group to a position which is determined by focal length data derived from actual positions of the first, second, and third lens groups and object distance data detected by an object distance measuring device. A method of controlling focusing of the zoom lens includes correcting an amount of deviation from focus caused by a zooming operation, by moving the focusing lens group.

Abstract: A zoom lens apparatus having a first pair of substantially parallel guide rods. A pair of carriage assemblies are mounted to the first pair of parallel guide rods each having lens element. A pair of lead screws are provided for driving the carriage assemblies. The screws are each mounted to the apparatus by a bearing block assembly such that the longitudinal axis of the lead screw is substantially parallel to the first pair of guide rods. The bearing block constrains the movement of the first lead screw along the longitudinal axis. A zero constraint threaded drive coupling is provided with each lead screw for moving the carriage along the guide rods. A motor is provided for rotating each of the drive screws.

Abstract: A lens barrel which has a lens holding member for holding a lens unit, a movement cam mechanism for moving the lens holding member in an optical-axis direction, a biasing member for biasing the lens holding member to shift a slide allowance of the movement cam mechanism in one direction, a biasing force receiving member for receiving a biasing force of the biasing member and a biasing force adjustment cam mechanism for moving the biasing force receiving member in the optical-axis direction so that the biasing force of the biasing member remains the same.