×

Electronic parking meter system

  • US 7,014,355 B2
  • Filed: 05/30/2001
  • Issued: 03/21/2006
  • Est. Priority Date: 10/02/1996
  • Status: Expired due to Fees
First Claim
Patent Images

1. An electronic parking meter system comprising:

  • an electronic parking meter for determining the time a parking space associated with the parking meter is occupied by a vehicle and receiving coins denoting desired parking time and indicating said time;

    an inductive loop vehicle detection sensor located to detect both the physical presence or absence of a vehicle in said parking space and emitting a respective signal indicative thereof;

    a microprocessor controller coupled to the sensor and the electronic parking meter for selectively controlling the electronic parking meter and the controller responsive to the sensor signal;

    the electronic parking meter indicating time provided upon payment with a vehicle occupying said space to obtain a fixed amount of time in accordance with the amount of payment, said electronic parking meter decrementing the indicated time;

    said controller initializing said electronic parking meter to zero when the sensor signals the controller that a vehicle no longer occupies the parking space;

    said detection sensor includes a variable oscillator circuit oscillating at a base frequency and responsive to the inductance of the inductive loop for providing said signals to the microprocessor indicating the presence or absence of a vehicle in the parking space;

    said microprocessor controller including a crystal oscillator producing pulses and operating at approximately 50 times the base frequency of the variable oscillator circuit and initiating a 12.5 ms long charge to said variable oscillator circuit every 2.5 seconds for the purpose of measuring the operating frequency of said circuit while conserving power as needed for the practical application of the technology in parking control;

    the presence or absence of a vehicle in the parking space causing a respective decrease or increase in the inductance of the inductive loop and a respective commensurate increase or decrease in the operating frequency and a respective decrease or increase in the period of the variable oscillator circuit, thereby decreasing or increasing the number of crystal oscillator pulses in each period of the variable oscillator circuit;

    said oscillator providing an output signal including said crystal oscillator pulses to said microprocessor controller; and

    said microprocessor controller superimposes the signals received from the variable oscillator circuit during each 12.5 ms time frame in which the variable oscillator circuit is charged with the crystal oscillator pulses clock to determine the presence or absence of a vehicle in the parking space.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×