Cam mechanism for driving a linearly-guided lens

A zoom lens comprising:

• first and second lens groups which are moved with respect to each other to change a focal length of said zoom lens;
• a linear guide barrel guided in a direction of an optical axis without rotating about said optical axis, said linear guide barrel having linear guide slots which extend parallel to said optical axis and linear guide projections at one end of said linear guide barrel to extend radially outwards;
• a cam barrel fitted on said linear guide barrel to be immovable in said direction of said optical axis relative to said linear guide barrel and to be rotatable about said optical axis relative to said linear guide barrel, said cam barrel having first cam grooves and second cam grooves which are formed on an inner peripheral surface of said cam barrel;
• a first lens frame which holds said first lens group and includes first cam followers which are respectively engaged in said first cam grooves, and first guide projections which are respectively engaged in said linear guide slots;
• and
• a second lens frame which holds said second lens group and includes second cam followers which are respectively engaged in said second cam grooves, and second guide projections which are respectively engaged in said linear guide slots;
• wherein said first lens frame and said second lens frame are moved in said direction of said optical axis by rotation of said cam barrel in accordance with the profiles of said first cam grooves and said second cam grooves, respectively;
• and
• wherein said linear guide projections and said linear guide slots are formed on said linear guide barrel at the same circumferential positions in a circumferential direction of said linear guide barrel, respectively

A cam mechanism for driving at least one lens group guided along an optical axis thereof in a predetermined manner, without rotating about said optical axis, said cam mechanism comprising:

• a linear guide barrel which is moveable in a direction of said optical axis without being rotatable about said optical axis;
• a plurality of linear guide projections formed on said linear guide barrel at one end thereof extending radially outwards;
• a cam barrel fitted on said linear guide barrel to be rotatable about said optical axis relative to said linear guide barrel and to be movable in said direction of said optical axis together with said linear guide barrel;
• a plurality of cam grooves formed on an inner surface of said cam barrel;
• a plurality of linear guide slots formed on said linear guide barrel extending parallel to said optical axis;
• at least one lens frame positioned inside said linear guide barrel;
• a plurality of projections formed on each of said at least one lens frame to be slidably engaged in said plurality of linear guide slots, respectively;
• and
• a plurality of cam followers formed on said plurality of projections to be engaged in said plurality of cam grooves, respectively;
• wherein said plurality of linear guide projections and said plurality of linear guide slots are formed on said linear guide barrel at the same circumferential positions of said linear guide barrel, respectively.