FACSIMILE SYSTEM

• US 3,813,483 A
• Filed: 06/01/1972
• Issued: 05/28/1974
• Est. Priority Date: 06/01/1972
• Status: Expired due to Term

• Current Assignee: Anritsu Corporation
• Original Assignee: Koichi Kurosawa, Ko Okubo
• Inventors: Kurosawa, Koichi, Okubo, Ko
• Primary Examiner(s): Safourek, Benedict V.
• Assistant Examiner(s): Masinick, Michael A.
• Application Number:
  US05/258,789
• Time in Patent Office: 726 Days
• Field of Search: 178/DIG.3,DIG.23,6 179/15BC 325/60
• US Class Current: 358/408
• CPC Class Codes: H04N 1/00095 Systems or arrangements for the transmission of the picture signal

Abstract

A facsimile system comprising a signal transmitting section comprising two scanners for scanning the surface of an original picture in parallel directions, a multiplex modulator for forming a composite picture signal by subjecting two carrier waves shifted 90* in phase from each other to 2-phase modulation by the picture signals obtained from said scanners; and a signal receiving section comprising a multiplex demodulator for subjecting said composite picture signal to 2-phase demodulation so as to separate it into two original picture signals and two recorders for reproducing the original picture upon receipt of the aforesaid two picture signals.

Claims

1. A facsimile system comprising:

a transmission section including two scanners for scanning the surface of an original picture being transmitted in parallel and in interleaved relation with each other and for detecting two respective picture signals;

a modulation carrier generator for generating two modulation carriers having the same frequency but having a phase difference of 90 degrees from each other;

two modulators respectively coupled to said two scanners and said carrier generator to modulate the two carriers respectively by the two picture signals; and

a mixer coupled to said modulators to mix the modulated signals from said two modulators thereby obtaining a composite picture signal to be transmitted; and

a receiving section including a receiving end for receiving the composite picture signal from said transmission section;

a demodulation carrier generator coupled to said receiving end to generate two demodulation carriers corresponding to the modulation carriers of said transmission section generated on the basis of the carrier component including in the composite picture signal;

two demodulators coupled to said demodulation carrier generator to demodulate the composite picture signal by the two demodulation carriers thereby to separate the composite picture signal into two picture signals;

D.C. reproducing means coupled to said two demodulators to reproduce the D.C. components included in the original picture signals; and

two recorders coupled to said D.C. reproducing means to scan the surface of a sheet of a recording medium in parallel corresponding to the scanning of the two scanners of the transmission section and reproduce the original picture on said recording medium on the basis of the two separated picture signals;

said demodulation carrier generator including a D.C. unbalance detector coupled to said two demodulators to detect an unbalance between two D.C. components respectively included in two demodulated picture signals;

an oscillator coupled to said D.C. unbalance detector, the oscillation frequency of said oscillator being varied by the output voltage of said detector;

a first frequency converter coupled to said oscillator and to said receiving end to frequency convert the carrier of the received composite picture signal by means of the output frequency of said oscillator;

a first band pass filter coupled to said first frequency converter to pass a predetermined frequency of the frequency converted carrier;

a second frequency converter coupled to said oscillator and to the output of said first band-pass filter to frequency convert the predetermined frequency passed through said first band-pass filter by means of the frequency of said oscillator back to the original carrier frequency;

a second band-pass filter coupled to said second frequency converter to filter the carrieR from the output of said second converter;

a first phase shifter coupled to said second band-pass filter to shift the filtered carrier from said second band-pass filter so as to coincide the phase of the filtered carrier with that of the carrier at the receiving end and coupled to one of said demodulators to supply the carrier therethrough as a demodulation carrier; and

a second phase shifter coupled between said first phase shifter and the other of said demodulators to further shift the carrier by 90* and then supply the 90* further shifted carrier to said other demodulator.

2. The facsimile system according to claim 1 wherein said modulation carrier generator comprises an oscillator of which the output is coupled to one of said modulators, and a phase shifter coupled to the output of said oscillator to shift 90* in phase the output signal from said oscillator.

3. The facsimile system according to claim 1 wherein said transmission section further includes two additional modulators each coupled between one of said scanners and one of said modulators to modulate the carrier having a frequency lower than the maximum picture frequency.

4. The facsimile system according to claim 1 wherein said D.C. reproducing means includes respective full wave rectifying means, each of said rectifying means being coupled between one of said demodulators and its respective recorder.