Patent ID: 7252388

Claim:
A projector which projects light to form an image on a surface of a screen and has a tilt-angle detecting capability, said projector comprising: a projection lens through which the light for forming the image on the screen is projected; a focus control section which controls focusing of the projection lens; and a tilt-angle detecting unit which detects a tilt angle of said surface of said screen with respect to an optical axis of light projected by said projector, said tilt-angle detecting unit comprising: a plurality of distance measuring sections, each of which includes at least two light receiving sections and at least two lenses, and which measure distances to a plurality of distance-measuring points on said screen; a control section which controls said plurality of distance measuring sections to measure said distances to said plurality of distance-measuring points on said screen; and a tilt-angle acquiring section which acquires said tilt angle of said surface of said screen with respect to said optical axis of said light projected onto said screen based on at least three measured distances measured by said plurality of distance measuring sections as controlled by the control section; wherein each of said distance measuring sections performs distance measuring by detecting a phase difference; wherein said plurality of distance measuring sections are laid out adjacent to the projection lens such that respective baselines of the plurality of distance measuring sections are adjacent to a circumference of the projection lens and cross each other, said baselines being lines connecting incidence centers of the associated light receiving sections of the distance measuring sections; and wherein the focus control section controls the focusing based on at least one of the distances measured by at least one of the distance measuring sections.