Flying spot scanner unaffected by ambient light

Abstract

A flying spot scanner is disclosed for scanning an object document or scene with a spot of light, and producing an electrical video signal representing the object. The scanner can be operated under normal ambient light conditions without a light-shielding enclosure. A light beam is deflected in repetitive scanning fashion over the object. The light beam is modulated in amplitude (intensity) at a radio frequency f.sub.c such as 1.2 MHz. A photodetector is positioned to receive light from the object, and it produces an unwanted electrical ambient light noise signal having a maximum frequency f.sub.a, and an electrical information signal consisting of a carrier at frequency f.sub.c modulated by a video signal having a maximum frequency f.sub.m, where f.sub.c - f.sub.m is larger than f.sub.a. The information signal is separated from the ambient light noise signal by a filter, and the information signal is demodulated to produce a facsimile or video information signal free of noise due to ambient light.

Dependencies are inferred from the claim text.