Temperature-compensated object sensing device and method therefor

A method for temperature-compensating the sensing of an object in a sensing zone in the presence of an environment temperature, comprising:

• producing a sensing response indicative of the distance of the object is from the sensing zone;
• generating a first periodical signal cycling at a first frequency that is dependent on the environment temperature and the response;
• isolating the sensing response from the generating of the first periodical signal step so that a second periodic signal is generated that cycles at a second frequency dependent on the environment temperature, but not dependent on the sensing response;
• and
• producing a temperature-compensated response indicative of whether the object is in the sensing zone from the first and second periodic signals.

A device for indicating to a vehicle driver to perform a certain driving action, the device being responsive to the presence of a vehicle in a sensing zone, wherein the device is exposed to an environment temperature, comprising:

• a sensor having a characteristic responsive to the distance of the vehicle is from the sensor;
• a signal generator coupled to the sensor for producing a first periodical signal cycling at a temperature-uncompensated frequency dependent on the sensor characteristic and the environment temperature;
• a de-coupling mechanism for de-coupling the sensor from the signal generator so that the signal generator produces a second periodical signal cycling at a reference frequency dependent on the environment temperature, but not substantially dependent on the characteristic of the sensor;
• a device for producing a temperature-compensated response from the temperature-uncompensated frequency and the reference frequency, wherein the temperature-compensated response is indicative of whether the vehicle is in the sensing zone;
• and
• driver stimulus device for indicating to the vehicle driver to perform the action when the vehicle has been detected in the sensing zone.

A gate operating system for controlling a gate in response to a vehicle being detected in a sensing zone, wherein at least a portion of the gate operating system is exposed to an environment temperature, comprising:

• a drive train for moving the gate between open and closed positions;
• a drive motor coupled to the drive train for causing the drive train to move the gate between the open and closed positions;
• a vehicle sensing device, comprising:
• a sensor having a characteristic responsive to the proximity of the vehicle is to the sensor;
• a signal generator coupled to the sensor for producing a first periodical signal cycling at a first frequency dependent on the sensor characteristic and the environment temperature;
• a de-coupling mechanism for de-coupling the sensor from the signal generator so that the signal generator produces a second periodical signal cycling at a second frequency dependent on the environment temperature, but not substantially dependent on the characteristic of the sensor;
• and
• a device for producing a temperature-compensated response indicative of whether the vehicle is in the sensing zone from the first and second periodical signals;
• and
• a motor control circuit coupled to the vehicle sending device for receiving therefrom the temperature-compensated response, and coupled to the motor for controlling the drive motor to cause the drive train to move the gate to the open position when the temperature-compensated response indicates the presence of the vehicle in the sensing zone.