Method to improve white light immunity of infrared motion detectors
First Claim
1. A motion detection system for detecting a presence of a moving object within a secure area, the system comprising:
- a first sensor responsive to light in a first range of wavelengths in the secure area, the first sensor generating a first output signal indicative of a first detected parameter of the light in the first range of wavelengths;
a second sensor proximate to the first sensor, the second sensor being responsive to light in a second range of wavelengths in the secure area;
a logic unit for compensating the first output signal based in part upon a reference signal indicative of a second parameter of the light in the second range of wavelengths; and
an alarm generation unit to generate an alarm if the first output signal exceeds a first threshold value, the first threshold value being a function of a baseline of the first output signal,wherein the second parameter comprises an intensity value of the light in the second range of wavelengths,wherein the reference signal is indicative of a differentiation of said intensity value with respect to time,wherein the reference signal is a second signal indicative of the second parameter of the light in the second range of wavelengths detected by the second sensor,wherein the logic unit compensates the first output signal only when the second parameter of the light in the second range of wavelengths exceeds a second preprogrammed threshold value, andwherein the second preprogrammed threshold value is added to an average value over a predetermined time period of the light in the second range of wavelengths detected by the second sensor over said predetermined time period.
4 Assignments
0 Petitions
Accused Products
Abstract
A system and method for improved white light immunity for IR motion sensors. The system comprises a first sensor responsive to light in a first range of wavelengths in the secure area, the first sensor generating a first output signal indicative of a first detected parameter of the light in the first range of wavelengths, a second sensor proximate to the first sensor, the second sensor being responsive to light in a second range of wavelengths in the secure area, and a logic unit for compensating the first output signal based in part upon a reference signal indicative of a second parameter of the light in the second range of wavelengths. The first sensor is a pyro-electric sensor and the second sensor is a visible light sensor. The second parameter comprises an intensity value of the light in the second range of wavelengths, wherein the reference signal is indicative of a differentiation of said intensity value with respect to time. The system further comprises an alarm generation unit to generate an alarm if the first signal exceeds a first threshold value, the first threshold value being a function of a baseline of the first signal.
-
Citations
20 Claims
-
1. A motion detection system for detecting a presence of a moving object within a secure area, the system comprising:
-
a first sensor responsive to light in a first range of wavelengths in the secure area, the first sensor generating a first output signal indicative of a first detected parameter of the light in the first range of wavelengths; a second sensor proximate to the first sensor, the second sensor being responsive to light in a second range of wavelengths in the secure area; a logic unit for compensating the first output signal based in part upon a reference signal indicative of a second parameter of the light in the second range of wavelengths; and an alarm generation unit to generate an alarm if the first output signal exceeds a first threshold value, the first threshold value being a function of a baseline of the first output signal, wherein the second parameter comprises an intensity value of the light in the second range of wavelengths, wherein the reference signal is indicative of a differentiation of said intensity value with respect to time, wherein the reference signal is a second signal indicative of the second parameter of the light in the second range of wavelengths detected by the second sensor, wherein the logic unit compensates the first output signal only when the second parameter of the light in the second range of wavelengths exceeds a second preprogrammed threshold value, and wherein the second preprogrammed threshold value is added to an average value over a predetermined time period of the light in the second range of wavelengths detected by the second sensor over said predetermined time period. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. A method for detecting a presence of a moving object within a secure area, the method comprising:
-
generating at a first sensor a first output signal indicative of a first detected parameter of light in a first range of wavelengths; compensating the first output signal based in part upon a reference signal indicative of a second parameter of light in a second range of wavelengths; generating an alarm if the first output signal exceeds a first threshold value, the first threshold value being a function of a baseline of the first output signal; compensating the first output signal only when the second parameter of the light in the second range of wavelengths exceeds a second preprogrammed threshold value; and determining an average value over a predetermined time period of the light in the second range of wavelengths detected by the second sensor over said predetermined time period, and adding the second preprogrammed threshold value to said average value, wherein the second parameter comprises an intensity value of the light in the second range of wavelengths, and wherein the reference signal is indicative of a differentiation of said intensity value with respect to time, and wherein the reference signal is a second output signal indicative of the second parameter of the light in the second range of wavelengths, the second output signal being generated by a second sensor responsive to the light in the second range of wavelengths. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
-
Specification