Patent ID: 7961269

Claim:
A projection optical unit comprising: an optical modulation element unit; an optical system which guides light from a light source to the optical modulation element unit; and a projection lens which projects light from the optical modulation element unit, wherein the optical modulation element unit comprises: a light-transmissive substrate; a film-type optical function member attached to the light-transmissive substrate; a reflective optical modulation element placed, at a predetermined distance, substantially parallel to the light-transmissive substrate; a cover member which surrounds a dustproof space between the light-transmissive substrate and the reflective optical modulation element; and a holding member which holds the light-transmissive substrate, wherein the holding member has an air guiding portion which guides an air flow to an air flow space along a first surface of the light-transmissive substrate, the first surface being a surface facing away from the reflective optical modulation element, wherein the cover member is formed so as not to surround the air flow space along the first surface, and wherein the film-type optical function member is attached to a second surface of the light-transmissive substrate, the second surface being a surface facing towards the reflective optical modulation element.