Optical detection and comparison apparatus for currency changing machine

Claim 1

APPARATUS FOR TESTING A DOCUMENT IN WHICH PORTIONS THEREOF EACH HAVE A CHARACTERISTIC RESPONSE TO RADIANT ENERGY INCIDENT THEREON TO DETERMINE IF THE DOCUMENT IN GENUINE OR OF A PARTICULAR CLASS, SAID APPARATUS INCLUDING: MEANS FOR PRODUCING AND DIRECTING RADIANT ENERGY ONTO EACH OF SAID PORTIONS RESPECTIVE OF THE DOCUMENT; MEANS DISPOSED TO RECEIVE THE RADIANT ENERGY DIRECTED TO EACH PORTION AFTER INCIDENCE THEREOF WITH THE CORRESPONDING PORTION; DETECTING MEANS OPERABLY ASSOCIATED WITH SAID RECEIVING MEANS AND RESPONSIVE TO THE ENERGY RECEIVED THEREBY FOR PRODUCING FIRST ELECTRICAL SIGNALS, EACH HAVING AN AMPLITUDE OF A MAGNITUDE DEPENDENT UPON THE INTENSITY OF SAID RECEIVED ENERGY FROM A CORRESPONDING PORTION; MEANS COUPLED WITH SAID DETECTING MEANS AND RESPONSIVE TO SAID FIRST SIGNALS FOR ADJUSTING THE AMPLITUDES OF AT LEAST CERTAIN OF SAID FIRST SIGNALS TO PROVIDE ALL OF THE FIRST SIGNALS WITH AMPLITUES WHICH, IT THE DOCUMENT IS GENUINE OR OF SAID CLASS, ARE SUBSTANTIALLY EQUAL; MEANS FOR GENERATING A SECOND ELECTRICAL SIGNAL HAVING AN AMPLITUDE WHICH VARIES IN ONE DIRECTION OVER A RANGE OF VALUES INCLUDING POSSIBLE MAGNITUDES OF SAID FIRST SIGNALS; COMPARATOR MEANS OPERABLY COUPLED WITH SAID GENERATING MEANS AND SAID ADJUSTING MEANS AND RESPONSIVE TO THE FIRST SIGNALS THEREFROM AND SAID SECOND SIGNAL FOR PRODUCING THIRD ELECTRICAL SIGNALS, EACH OF THE LATTER HAVING A PREDETERMINED DURATION AND OCCURRING IN TIME WHEN THE AMPLITUDE OF SAID SECOND SIGNAL AND THE AMPLITUED OF A CORRESPONDING FIRST SIGNAL FROM THE ADJUSTING MEANS ARE SUBSTANTIALLY EQUAL; AND OUTPUT MEANS OPERABLY COUPLED WITH SAID COMPARATOR MEANS AND RESPONSIVE TO SAID THIRD SIGNALS FOR PRODUCING AN OUTPUT SIGNAL WHEN SAID THIRD SIGNALS OCCUR IN AN OVERLAPPING TIME RELATIONSHIP, WHEREBY THE OUTPUT SIGNAL IS PRODUCED IF SAID PORTIONS OF THE DOCUMENT HAVE SAID CHARACTERISTIC RESPONSED INDICATING THAT THE DOCUMENT IS GENUINE OR OF SAID CLASS.