Mark sensing system

Claim 1

A MARK SENSING SYSTEM FOR SENSING PREPRINTED TIMING MARKS AND MARKS RECORDED IN PREDESIGNATED MARKING AREAS ON A DOCUMENT AND PROVIDING OUTPUT INDICATIONS CORRESPONDING TO THE PRESENCE AND ABSENCE OF SAID RECORDED MARKS IN SAID PREDESIGNATED MARKING AREAS COMPRISING: A TIMING CHANNEL AND AT LEAST ONE READING CHANNEL; SAID TIMING CHANNEL COMPRISING A TRANSDUCER MEANS FOR SENSING A PREPRINTED TIMING MARK AND PROVIDING AN ELECTRICAL SIGNAL IN RESPONSE THERETO; MEANS TO DIFFERENTIATE SAID ELECTRICAL SIGNAL TO PRODUCE A FIRST PULSE OF ONE POLARITY FOLLOWED BY A SECOND PULSE OF THE OPPOSITE POLARITY; A FIRST DEVICE SETTABLE BY ELECTRICAL SIGNALS TO AT LEAST TWO STABLE STATES AND PROVIDING OUTPUT SIGNALS CORRESPONDING THERETO; MEANS RESPONSIVE TO THE TOTAL ABSOLUTE MAGNITUDE OF SAID FIRST AND SECOND PULSES FOR ACTUATING SAID FIRST DEVICE;