Optical element retracting mechanism for a retractable lens

An optical element retracting mechanism for a retractable lens including an optical system having a plurality of optical elements, the optical element retracting mechanism comprising:

• a linearly movable ring configured to be guided along an optical axis of the optical system without rotating, and further configured to retract along said optical axis toward a plane, when said retractable lens moves from an operating state to a fully-retracted state;
• a retractable holder configured to support a retractable optical element as one of the plurality of optical elements, said retractable holder positioned inside and supported by said linearly movable ring, such that said retractable holder is movable in a plane generally orthogonal to said optical axis;
• a holding device configured to hold said retractable holder such that the retractable optical element remains positioned along the optical axis when said retractable lens is in the operating state;
• a cam provided to a stationary member positioned behind said linearly movable ring, said cam configured to press said retractable holder to move said retractable holder such that the retractable optical element retracts to a radially retracted position outside of the optical axis when said linearly movable ring, together with said retractable holder, retracts toward the plane;
• and
• a guide key and a key groove, one of which is located on said stationary barrel, the other of which is located on said linearly movable ring, respectively, wherein said guide key is engaged in said key groove to regulate a direction of movement of said linearly movable ring relative to said stationary barrel at least when said retractable holder is held at a radially retracted position on said plane at which said retractable optical element is positioned at the outside of the position of the optical axis.