Method and apparatus for detecting direction and speed using PIR sensor

A method of detecting motion, comprising the steps of:

• orienting a pair of opposed-polarization sensing elements of a PIR sensor in a motion plane;
• arranging said opposed-polarization sensing elements to provide a composite signal having a positive primary peak in response to a source of IR radiation moving across said sensing elements in a first direction in said motion plane and having a negative primary peak in response to the source of IR radiation moving across said sensing elements in an opposite direction to said first direction in said motion plane;
• and
• discriminating the polarity of the primary peak of said composite signal to determine the direction of motion of an IR source moving in said motion plane.

Apparatus for determining the velocity of a moving source of IR radiation comprising:

• first and second PIR sensors, each PIR sensor including first and second sensing elements, each said sensing element having a polarization and the sensing elements of each PIR sensor being electrically coupled with their polarizations in opposition to one another and being disposed and arranged to provide a composite signal having a positive primary peak in response to a source of IR radiation moving in a first direction and having a negative primary peak in response to the source of IR radiation moving in an opposite direction to said first direction;
• direction determining means, coupled to each said PIR sensor and responsive to said composite signal from each said PIR sensor, for determining the direction of movement of an IR source across each said PIR sensor;
• and
• means, coupled to said direction determining means, for generating a signal proportional to the average speed of the IR source as it transits said first and second PIR sensors.