Magnified image projector apparatus

摘要

A magnified image projector apparatus such as a microfilm strip reader or a microfilm strip printer apparatus having an automatic focus control system and a tiltable reflector mirror by means of which the image-carrying beam passed through an image projection lens may be directed to advance along one path of light toward the viewing screen to along another path of light to a photodetector unit of the focus control system which comprises a focusing lens located in the path of light between the tiltable reflector mirror and the photodetector unit so that the image-carrying beam passed through the projection lens may be incident on the photodetector unit to a reduced scale. This arrangement of the focussing lens allows significant reduction in the effective light receiving area of the photodetector unit used in the apparatus while enabling the photodetector unit to accurately detect the location at which the beam is focussed by the projection lens.