Infrared detector system
First Claim
1. An infrared detector system comprising;
- at least a pair of spaced apart infrared sensing elements capable of generating respective first and second electrical signals;
a plurality of reflective surfaces subtending respective different object fields of view, about a respective optical axis, each reflective surface having a focal point positioned on its optical axis between the respective infrared sensing elements and reflecting optimum energy resolution of an image configuration compatible to the sensing element configuration whereby movement of an infrared emitting object will produce a sequence of electrical signals from the infrared sensing elements; and
means for processing the electrical signals to produce an alarm signal in response to predetermined enabling conditions.
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Abstract
An improved infrared detector system includes a pair of thin film thermopile sensing elements that receives reflected energy from aspheric reflectors that are designed to provide optimum energy resolution. An absorbing coating can be placed above the sensors and extending beyond the periphery to improve the signal to noise ratio. A high gain low noise D.C. amplifier is coupled to the output of the infrared sensing elements while a high pass amplifier and low pass amplifier are designed to pass an amplified signal in the frequency range from approximately 0.2 Hz to 15 Hz. Finally, a combined peak detector and time dependent integrator summing amplifier circuit provides an enabling predetermined threshhold detection gate that requires either a predetermined large signal level or a multiple of small electrical signals within a preselected interval to produce an alarm enabling signal.
52 Citations
21 Claims
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1. An infrared detector system comprising;
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at least a pair of spaced apart infrared sensing elements capable of generating respective first and second electrical signals; a plurality of reflective surfaces subtending respective different object fields of view, about a respective optical axis, each reflective surface having a focal point positioned on its optical axis between the respective infrared sensing elements and reflecting optimum energy resolution of an image configuration compatible to the sensing element configuration whereby movement of an infrared emitting object will produce a sequence of electrical signals from the infrared sensing elements; and means for processing the electrical signals to produce an alarm signal in response to predetermined enabling conditions. - View Dependent Claims (2, 3, 4, 6, 7, 8, 9, 10, 11, 12, 13, 15, 17, 18, 19, 20)
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14. An infrared detector system comprising:
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detector means including at least a pair of infrared sensing elements capable of generating respective first and second electrical signals of opposite polarity; reflecting means including a plurality of aspheric reflector segments that partition the object field of view into discrete regions, each reflector segment subtending a different region and focusing incident infrared energy onto the detector means with minimal image aberration; circuit means for processing electrical signals from the detector means including a high gain low noise D.C. amplifier coupled to the output of the infrared sensing elements, a high pass amplifier and low pass amplifier coupled respectively in series to the output of the D.C. amplifier to pass an amplified signal in the frequency range of approximately 0.2 Hz to 15 Hz and a combined peak detector and time dependent integrator summing amplifier circuit receiving the signal from the low pass amplifier to provide an enabling predetermined threshhold detection gate that requires one of, a predetermined large signal level and a multiple of small electrical signals within a preselected interval, to produce an alarm enabling signal, and means responsive to the alarm signal to indicate the presence of an intruder.
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Specification