Electro-optical label reading system using pulse width detection circuit

Claim 1

IN AN ELECTRO-OPTICAL LABEL READING SYSTEM INCLUDING A LABEL CONTAINING CODED DATA, APPARATUS FOR OPTICALLY SCANNING SAID LABEL, AND A SENSOR OPERATIVE IN RESPONSE TO LIGHT REFLECTED FROM SAID LABEL TO PRODUCE SIGNAL PULSES OF VARYING AMPLITUDE AND WAVE SHAPE REPRESENTATIVE OF SAID CODED DATA, A CIRCUIT FOR MEASURING THE MID-AMPLITUDE WIDTH OF SAID SIGNAL PULSES COMPRISING: A DELAY LINE HAVING AN INPUT TERMINAL AND FIRST AND SECOND OUTPUT TAPS, THE DELAY BETWEEN SAID INPUT TERMINAL AND SAID SECOND OUTPUT TAP BEING TWICE THE DELAY TO SAID FIRST OUTPUT TAP AND APPROXIMATELY EQUAL TO THE MAXIMUM RISE TIME OF SAID SIGNAL PULSES, MEANS COUPLING SAID SIGNAL PULSES TO THE INPUT TERMINAL OF SAID DELAY LINE, FIRST MEANS TO WHICH SAID SIGNAL PULSES ARE ALSO APPLIED FOR ATTENUATING BY HALF THE AMPLITUDE OF SAID INPUT SIGNAL PULSES, SECOND MEANS COUPLED TO THE SECOND OUTPUT TAP OF SAID DELAY LINE FOR ATTENUATING BY HALF THE AMPLITUDE OF DELAYED SIGNAL PULSES APPERATING THEREAT, A DIFFERENCE AMPLIFIER HAVING FIRST AND SECOND INPUT TERMINALS, MEANS COUPLING SAID ATTENUATED SIGNALS FROM SAID FIRST AND SECOND MEANS TO THE FIRST INPUT TERMINAL OF SAID DIFFERENCE AMPLIFIER, MEANS COUPLING THE DELAYED SIGNAL PULSES APPEARING AT THE FIRST OUTPUT TAP OF SAID DELAY LINE TO THE SECOND INPUT TERMINAL OF SAID DIFFERENCE AMPLIFIER, AND MEANS COUPLED TO SAID DIFFERENCE AMPLIFIER AND OPERATIVE IN RESPONSE TO THE SIMULTANEOUS APPLICATION TO SAID FIRST AND SAID INPUT TERMINALS, RESPECTIVELY, OF SAID DIFFERENCE AMPLIFIER OF SAID ATTENUATED PULSE SIGNALS AND A SIGNAL FROM THE FIRST OUTPUT TAP OF SAID DELAY LINE TO PRODUCE RECTANGULAR PULSES OF UNIFORM AMPLITUDE.