The htk book version

A controlled projection reader is disclosed in which film having indicia thereon is passed by an aperture area. A lamp and lens arrangement projects the indicia on the film onto a screen or the like. A scanning disc is mounted relative to the aperture area so as to be rotatably driven relative to the film and aperture area. Means on the disc permits scanning or line-type reading to occur. A masking disc is mounted for relative movement relative to the scanning disc to permit either scan-type operation or full line projection. The film is looped toward the scanning disc to reduce the distance between the aperture mask, image plane on the film and the scanning disc so as to project a clear border line on the screen. Means for advancing the film in response to rotational movement of the scanning device is provided.