Patent ID: 8039799
Filing Date: 2011-10-18
Classification: G01J,G08B

Abstract:
1. A motion detection system for detecting the presence of a moving object within a detection zone, comprising: a first sensor responsive to light in a first range of wavelengths in the detection zone and generating a first output signal indicative of a first detected parameter of the light in the first range; a second sensor responsive to light in a second range of wavelengths in the detection zone and generating a second output signal indicative of a second detected parameter of the light in the second range, wherein the second range of wavelengths is different from the first range of wavelengths; and a processing component for generating a variable threshold value for the first sensor based upon at least maximum and minimum output signals from the second sensor within a predetermined period of time, and for comparing the first output signal with the variable threshold value, wherein the processing component generates an activating signal if the first output signal exceeds the variable threshold value.