Illumination intensity controller for optical projector with zoom lens

摘要

The position of the zoom lens (10) and the intensity of the surrounding illumination are measured (13,17) during image projection and stored in memory (16). A controller (15) reads out the stored data and adjusts the brightness of the light source (12) by operation on its driver (11). The zoom lens position detector is based on the variation of an adjustable resistance by movement of the lens holder whereby the angle of projection is enlarged or diminished.