Sensor signal processing for automatic convergence

摘要

A projection display device includes a screen image measuring arrangement and is subject to unwanted illumination. The measuring arrangement comprises a photo sensor located adjacent to an edge of the screen for generating an output signal having a first component responsive to illumination by a projected image and a second component responsive to illumination by the unwanted illumination. A filter is coupled to the photo sensor for filtering the output signal to pass the first component of the output signal and to attenuate an amplitude of the second component of the output signal.