Radiation sensitive tape speed sensor

Claim 1

TAPE SPEED SENSING APPARATUS INA TAPE TRANSPORT DEVICE COMPRISING (A) A PHOTO-ELECTRIC RECTIFIER, (B) MEANS FOR SUPPLYING AN AC VOLTAGE TO THE RECTIFIER, (C) A LIGHT SOURCE POWDERED BY SAID AC VOLTAGE, (D) MEANS FOR DIRECTING A BEAM OF LIGHT FROM THE LIGHT SOURCE TO THE RECTIFIER, (E) MEANS FOR INTERRUPTING THE BEAM AT A FREQUENCY PROPORTIONATE TO THE VELOCITY OF TAPE IN THE TRANSPORT DEVICE SO THAT THE RECTIFIER PASSES PULSES AT SAID FREQUENCY INCLUDING (1) A ROTATABLE ROLLER ENGAGEABLE BY THE TAPE SO THAT THE ROTATIONAL VELOCITY OF THE ROLLER IS PROPORTIONATE TO THE VELOCITY OF THE TAPE PAST THE ROLLER, AND (2) A SLOTTED OPAQUE DISC CONNECTED TO THE ROLLER FOR ROTATION THEREBY AND DISPOSED TRANSVERSELY OF THE BEAM, (F) MEANS FOR REGULATING SAID AC VOLTAGE SO THAT THE INTENSITY OF THE LIGHT BEAM IS CONSTANT AND THE AMPLITUDE OF THE PULSES PASSED BY THE RECTIFIER IS CONSTANT, AND (G) MEANS COUPLED TO THE RECTIFIER AND HAVING A DC VOLTAGE AS AN OUTPUT, THE OUTPUT VOLTAGE BEING PROPORTIONATE TO THE FREQUENCY OF THE PULSES FROM THE RECTIFIER.