Patent ID: 7199950

Claim:
An extension spring installation structure of a lens barrel including a pair of relatively movable members which are movable relative to each other in an optical axis direction and at least one of which supports an optical element, said extension spring installation structure comprising: at least one extension coil spring which biases said pair of relatively movable members in directions to approach each other, said extension coil spring including a coil spring portion and a pair of engaging portions provided at opposite ends of said coil spring portion, respectively; and at least one spring-hook portion and at least one tilt-restriction portion which are formed on at least one of said pair of relatively movable members, wherein one of said pair of engaging portions is engaged with said spring-hook portion by a movement of said extension coil spring toward the spring-hook portion in a direction along an axis of said coil spring portion, wherein said spring-hook portion is shaped so as to be prevented from being disengaged from said one engaging portion of said extension coil spring even in the case where said extension coil spring is moved along said axis of said coil spring portion in a state where said one engaging portion of said extension coil spring is engaged with said spring-hook portion, and wherein said tilt-restriction portion prevents said coil spring portion from moving in a radial direction of said coil spring portion in said state where said one engaging portion of said extension coil spring is engaged with said spring-hook portion.