Optical diaphragm and projector

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 respectively 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 attached to the vane plate, the bearing allowing each of the rotary shafts to be inserted therein so as to be supported by each of the rotary shafts,
• an adjacent pair of the vane plates is attached to the base plate and the vane holder via the rotary shafts such that the adjacent pair of the vane plates is spaced apart from each other by a predetermined distance in the optical axis direction of the light beam,
• the bearing is arranged such that, when the optical diaphragm is assembled, a thickness of the bearing in the optical axis direction of the light beam is larger than that of the vane plate, and that an end surface in the optical axis direction of the bearing abuts on at least one of the base plate and the vane holder, 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.

A projector, comprising:

• a light source device;
• an optical modulator for modulating a light beam irradiated by the light source in accordance with image information;
• a projection optical device for projecting the light beam modulated by the optical modulator in an enlarged manner;
• and an optical diaphragm for adjusting a light quantity of an incident light beam, wherein
• the optical diaphragm is disposed on an optical path of the light beam irradiated from the light source device and traveling to the optical modulator for adjusting a light quantity of the light beam irradiated from the light source device and traveling to the optical modulator, the optical diaphragm including:
• 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 respectively 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,
• 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.