Optical motion detector detecting visible and near infrared light

A method for detecting motion from a perturbated lighting scene and for identifying the type of perturbated lighting, comprising the steps of:

• detecting an instantaneous visible light intensity from a lighting scene;
• transducing said instantaneous visible light intensity into a first value functionally related to said visible light intensity;
• storing a second value corresponding to a maximum detected intensity of said lighting scene;
• determining a difference between said first and second values;
• detecting an instantaneous near-infrared light intensity from said lighting scene;
• transducing said instantaneous near-infrared light intensity into a third value functionally related to said near-infrared light intensity;
• storing a fourth value corresponding to a maximum detected intensity of said near-infrared lighting scene;
• determining a difference between said third and fourth values;
• providing an intrusion warning output if said difference between said first and second values exceeds a predetermined limit, .epsilon., and providing an output indicating a perturbation of fluorescent light;
• providing an intrusion warning output if said difference between said third and fourth values exceeds said predetermined limit, .epsilon., and providing an output indicating a perturbation of near-infrared light;
• and
• providing an intrusion warning output and an output indicating a perturbation of incandescent light if each of said differences between said first and second values, and between said third and fourth values, exceed said predetermined limit, .epsilon., and if said instantaneously detected visible light corresponding to said first value is detected substantially simultaneously to said detection of said near-infrared light corresponding to said third value.

An optical motion detector, comprising:

• a first photodetector having an output functionally related to the intensity of visible light illuminating said photodetector;
• a second photodetector having an output functionally related to the intensity of near-infrared light illuminating said photodetector;
• a first signal processing network operably coupled to receive said output of said first photodetector, said first signal processing network including:
• a first low-pass filter operably coupled to said first photodetector, said low pass filter providing an output having a frequency of about 40 hertz and less;
• a first sample-and-hold operably coupled to receive said output of said first low-pass filter, said first sample-and-hold storing a value corresponding to a maximum detected intensity of said illumination of said first photodetector with said visible light;
• a first comparator network operably coupled to receive said output of said first low-pass filter and said output of said first sample-and-hold, said first comparator including:
• a first resistor operably coupled to receive said output of said first photodetector;
• a first amplifier operably coupled to said first resistor, said first amplifier providing an output;
• a second amplifier operably coupled to said first sample-and-hold, said second amplifier providing an output;
• and
• a first comparator operably coupled to receive said outputs of said first and second amplifiers, said first comparator changing state when a difference between said value stored by said first sample-and-hold and said output of said first photodetector exceeds a predetermined limit,
• a first pulse stretcher operably coupled to said first comparator, said first pulse stretcher changing state from a high to a low condition when said first comparator changes state from a high to a low condition;
• a second signal processing network operably coupled to receive said output of said second photodetector, said second signal processing network including:
• a second low-pass filter operably coupled to said second photodetector, said low pass filter providing an output having a frequency of about 40 hertz and less;
• a second sample-and-hold operably coupled to receive said output of said second low-pass filter, said second sample-and-hold storing a value corresponding to a maximum detected intensity of said illumination of said second photodetector with said near-infrared light;
• a second comparator network operably coupled to receive said output of said second low-pass filter and said output of said second sample-and-hold, said second comparator including:
• a second resistor operably coupled to receive said output of said second photodetector;
• a third amplifier operably coupled to said second resistor, said third amplifier providing an output;
• a fourth amplifier operably coupled to said second sample-and-hold, said fourth amplifier providing an output;
• and
• a second comparator operably coupled to receive said outputs of said third and fourth amplifiers, said second comparator changing state when a difference between said value stored by said second sample-and-hold and said output of said second photodetector exceeds a predetermined limit;
• a second pulse stretcher operably coupled to said second comparator, said second pulse stretcher changing state from a high to a low condition when said second comparator changes state from a high to a low condition;
• and
• a logical processor operably coupled to said first and second pulse stretchers, said logical processor providing an intrusion warning output indicating a change in intensity of fluorescent light, an intrusion warning output indicating said change in said intensity of said near-infrared light, and an intrusion warning output indicating a change in intensity of an incandescent light scene whenever said detected change in said intensity of said near-infrared light is detected substantially simultaneously with said detected change in intensity of said near-infrared light.

An optical motion detector, comprising:

• means for detecting visible light intensity;
• means for detecting near-infrared light intensity;
• and
• network means operably coupled to said visible light detecting means and said near-infrared light detecting means for providing an output warning indicating a change in intensity of fluorescent light, for providing an output warning indicating a change in intensity in said detected near-infrared light, and for providing an output warning indicating a change in intensity in incandescent light whenever said detected change in intensity of said visible light is detected simultaneously with said detected change in intensity of said near-infrared light.