Patent ID: 6634757
Filing Date: 2003-10-21
Classification: H04N

Abstract:
A projection display apparatus in which a light emitted from a light source enters a light valve, an image corresponding to an input video signal is formed in an image-forming plane of the light valve, and the formed image is projected onto a screen through an optical system including a zoom lens, the projection display apparatus comprising:a distance-measuring device automatically measuring a distance between the projection display apparatus and the screen; a first processor for calculating an area of an image projected onto the screen on the basis of a target position of the zoom lens and the distance measured by the distance-measuring device; a photometer for measuring illuminance in the neighborhood of the image projected onto the screen; a second processor for calculating a black-level correction value from the area of the image calculated by the first processor and the illuminance measured by the photometer; and a light-source-power controller for controlling power supplied to the light source on the basis of the black-level correction value calculated by the second processor.