Patent ID: 7677740
Filing Date: 2010-03-16
Classification: F21V,G03B,H04N

Abstract:
1. An optical diaphragm for adjusting a light quantity of an incident light beam, comprising: a base plate extending along a plane orthogonal to an optical axis of the light beam, the base plate having an aperture for transmitting the light beam; a plurality of light-shielding vanes attached to a circumferential portion of the aperture of the base plate in a manner rotatable along the plane orthogonal to the optical axis of the light beam, the light-shielding vanes being rotated to change an aperture area of the aperture for transmitting the light beam to adjust the light quantity of the light beam; a vane holder for pressing the plurality of light-shielding vanes to the base plate in a manner that the light-shielding vanes are rotatable; a plurality of rotary shafts fixed between the base plate and the vane holder, the rotary shafts each rotatably supporting each of the plurality of light-shielding vanes; and a vane-driving mechanism movably attached to the base plate and engaged with the plurality of light-shielding vanes, the vane-driving mechanism moving relative to the base plate to rotate the plurality of light-shielding vanes, wherein the plurality of light-shielding vanes each include a vane plate for intercepting the incident light beam; and a bearing integrally provided to the vane plate, the bearing each allowing each of the rotary shafts to be inserted therein so as to be supported by each of the rotary shafts, the vane plate is perpendicularly attached to the bearing, the plurality of light-shielding vanes move in parallel to each other in an opening and closing direction thereof without crossing with each other, and an adjacent pair of the light-shielding vanes are so arranged that thicknesses of the bearings of the adjacent pair of the light-shielding vanes are different from each other in the optical axis direction.