PROJECTION TYPE IMAGE DISPLAY APPARATUS WITH CIRCUIT FOR CORRECTING LUMINANCE NONUNIFORMITY

摘要

In a projection type image display apparatus, the screen is divided and a memory to record luminance correction data corresponding to the divided regions is provided, and addresses of the divided regions of the screen are set by an address counter, synchronized with the input video signal. The luminance correction data are read successively by inputting the addresses to the memory, and luminance nonuniformity on the screen is corrected through operational processing of the correction value converted in an analog value by a D/A converter and the input video signal. The luminance correction data is obtained by computing measurement results of respective luminance characteristics of red, green, and blue colors on the screen and separately recorded as an amplitude correction component and a DC level correction component. By multiplying and adding the correction data to the input video signal respectively, nonuniformities in luminance and color from low luminance level to high luminance level can be precisely corrected. Also, as the read start position and read direction of the memory can be set corresponding to sweep direction of a projection type image display apparatus, the projection direction to the screen in a projection type image display apparatus can be easily changed without affecting the operation of luminance correction.