Patent ID: 7593169
Filing Date: 2009-09-22
Classification: G02B,G03B

Abstract:
1. An optical option attachment ring comprising: a ring body into which a lens barrel is inserted; a clamping ring rotatably fastened on the periphery of the ring body; an elastic member arranged between the ring body and the clamping ring; and an abutting portion which is provided on the clamping ring and abuts on the elastic member according to the rotational position of the clamping ring to elastically deform the elastic member to cause at least a part of the elastic member to project further inwards than the inner peripheral surface of the ring body and to be positioned in a groove formed in the lens barrel, wherein the ring body includes an opening causing the periphery and the inner peripheral surface of the ring body to communicate with each other, the elastic member is a leaf spring with a fixed end fixed to the ring body, a free end movable between the inner peripheral surface of the clamping ring and the periphery of the ring body in the radial direction and a curved portion formed between the fixed end and the free end and positioned in the opening, and the clamping ring is provided with relatively thin and thick portions on the inner peripheral surface thereof and rotated to cause the thick portion to abut on the free end of the elastic member to elastically deform the elastic member to cause the curved portion to project further inwards than the inner peripheral surface of the ring body from the opening and to be positioned in a groove formed in the lens barrel.