Method and apparatus for time compression of facsimile transmissions

Abstract

In a facsimile transmission system, a transmitter comprises a read photodetector which scans a document for video content and a lead photodetector which scans the document in advance of the read photodetector. The output of the read photodetector is coupled to a modulator which generates signals for transmission to a facsimile receiver at a remote location. The output of the read photodetector and the lead photodetector are also coupled to timing circuitry which automatically initiates a fast scanning mode for the read and lead photodetectors after a predetermined time lapse without detection of a dark, information-bearing area on the document. The facsimile receiver which comprises a stylus for scanning a copy medium and a demodulator for controlling marking on the copy medium by the stylus also includes timing circuitry for automatically initiating a fast scanning mode after a predetermined lapse in time between received signals representing dark, information-bearing areas. The fast scanning modes at the transmitter and receiver are terminated in response to the first dark, information-bearing area detected by the read or lead photodetector.

Dependencies are inferred from the claim text.