Vehicular parking systems

Claim 1

THE COMBINATION WITH A PARKING METER HAVING A ZERO-SET MECHANISM OPERABLE TO PREDETERMINE PARKING TIME AND AUTOMATICALLY SET TO ZERO UPON EXPIRATION OF SAID PARKING TIME, TRIPPING MEANS FOR SETTING SAID METER TO ZERO BEFORE EXPIRATION OF SAID PARKING TIME, TRANSDUCING MEANS FOR GENERATING AND DIRECTING ULTRASONIC ENERGY PULSES INTO THE PARKING SPACE MONITORED BY SAID PARKING METER AND WHICH SPACE MAY BE OCCUPIED BY A VEHICLE, PULSING MEANS FOR PERIODICALLY ENERGIZING SAID TRANSDUCING MEANS FOR PRODUCING SAID ULTRASONIC PULSES, SAID TRANSDUCING MEANS BEING DISPOSED TO RECEIVE REFLECTIONS OF SAID ULTRASONIC PULSES FROM A VEHICLE AND IN ITS ABSENCE FROM THE ROADBED, AN OUTPUT CIRCUIT, CONNECTIONS INCLUDING SWITCHING MEANS BETWEEN SAID OUTPUT CIRCUIT AND SAID TRANSDUCING MEANS FOR PREVENTING OUTPUT SIGNALS DURING GENERATION OF SAID ULTRASONIC PULSES AND FOR DEVELOPMENT AT SAID OUTPUT CIRCUIT OF SIGNALS REPRESENTATIVE OF REFLECTIONS PRODUCED BY SAID ULTRASONIC PULSES, AND MEANS FOR OPERATING SAID TRIPPING MEANS IN RESPONSE TO OUTPUT SIGNALS FROM SAID OUTPUT CIRCUIT REPRESENTATIVE OF REFLECTIONS FROM THE ROADBED ARISING DUE TO THE ABSENCE FROM SAID PARKING SPACE OF SAID VEHICLE BEFORE THE EXPIRATION OF ITS PARKING TIME.