Flame Detector Using Nearband IR Temporal Signal Processing
First Claim
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1. A flame detector comprising:
- a first, visible light sensing photodiode;
visible light related processing circuits, coupled to the first photodiode to establish instantaneous dc related signal changes and peak-to-peak ac signals over a predetermined time interval;
a second, near infrared sensing photodiode;
infrared related processing circuits, coupled to the second photodiode to establish instantaneous dc related signal changes and peak-to-peak ac signals over a predetermined time interval; and
control circuits to determine the presence of a fire condition using amplitude components of the processed visible light and near infrared signals.
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Abstract
A flame detector incorporates visible and near infrared sensors in common with processing circuits to form processed instantaneous, dc type, signal values minus an average value and peak-to-peak ranges of values of ac-type signals over a measurement time interval on the order of three seconds. The resulting values are further processed to determine the presence of a fire condition by comparing them to a predetermined threshold.
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Citations
15 Claims
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1. A flame detector comprising:
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a first, visible light sensing photodiode; visible light related processing circuits, coupled to the first photodiode to establish instantaneous dc related signal changes and peak-to-peak ac signals over a predetermined time interval; a second, near infrared sensing photodiode; infrared related processing circuits, coupled to the second photodiode to establish instantaneous dc related signal changes and peak-to-peak ac signals over a predetermined time interval; and control circuits to determine the presence of a fire condition using amplitude components of the processed visible light and near infrared signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of operating a visible light sensor and a near infrared sensor to make a fire determination comprising:
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providing a visual light sensor and a near infrared sensor; processing selected amplitude values of signals received from the sensors; establishing that an amplitude of a near infrared processed signal exceeds a predetermined threshold; establishing a renewal window of a predetermined minimum duration; and determining, using at least the processed amplitude values for both sensors, the presence of a fire. - View Dependent Claims (12, 13, 14, 15)
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Specification