Patent ID: 7595940
Filing Date: 2009-09-29
Classification: G02B,G03B

Abstract:
1. A lens barrel, comprising: a) a plurality of lens groups each having at least one lens; b) a plurality of lens retaining frames each retaining corresponding one of the plurality of lens groups; c) a telescopic cylinder containing therein the plurality of lens groups and the plurality of lens retaining frames; d) a lens retaining frame driving device configured to drive at least one of the lens retaining frames; at least one portion of the plurality of lens groups being collapsed to store the plurality of lens groups in a collapsed state and at least one portion of the plurality of lens groups being moved toward a subject in a photographable state, the plurality of lens retaining frames including a retractable lens retaining frame configured to retain and retract at least one of the plurality of lens groups to a retracted position substantially out of the telescopic cylinder in the collapsed state and configured to move the corresponding at least one of the plurality of lens groups from the retracted position to a photographing position in the photographable state such that an optical axis of the corresponding at least one of the plurality of lens groups substantially coincide with an optical axis of the other lens group of the plurality of lens groups in order that all of the plurality of lens groups be substantially aligned on the same optical axis; and e) a position detector configured to detect a change in a position of the retractable lens retaining frame in the collapsed state and in the photographable state, the retractable lens retaining frame including a cam portion configured to change a position of the retractable lens retaining frame between the retracted position which is substantially out of the telescopic cylinder and which is distant from the optical axis of said the other lens group, and the photographing position in which the optical axis of the corresponding at least one of the plurality of lens groups retained by the retractable lens retaining frame is positioned substantially on the optical axis of said the other lens group and in which the retractable lens retaining frame is moveable in a direction substantially coaxial with the optical axis of said the other lens group, so as to detect, based on an amount of a displacement of the retractable lens retaining frame in the direction substantially coaxial with the optical axis of said the other lens group, a displacement of the retractable lens retaining frame in a direction in which the optical axis of the corresponding at least one of the plurality of lens groups retained by the retractable lens retaining frame approaches and separates away from the optical axis of said the other lens group between the collapsed state and the photographable state, and a displacement of the retractable lens retaining frame in the direction substantially coaxial with the optical axis of said the other lens group in the photographable state, the lens retaining frame driving device including a lead screw configured to advance and retreat the retractable lens retaining frame in a direction substantially extending parallel with the optical axis of said the other lens group, and a female screw member screwed on the lead screw and capable of being advanced and retracted by rotation of the lead screw in an axial direction of the lead screw which extends substantially in parallel with the optical axis of said the other lens group, the female screw member including a contact portion configured to contact with the cam portion to change the position of the retractable lens retaining frame between the retracted position and the photographing position by the rotation of the lead screw, and the position detector including a detected portion provided on the female screw member so as to detect the position of the female screw member in the axial direction at the time of the rotation of the lead screw, and a detecting portion arranged in an area of movement of the detected portion for detecting a displacement of the detected portion in the axial direction.