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US 4,733,077 AGranted
Noise immune infrared readout circuitry
AssigneeHughes Aircraft Company
InventorsSteve D. Gaalema, Mary J. Hewitt, Arthur L. Morse
Life of this patent
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Abstract
A new technique, and output encoding circuits using that technique, are disclosed for interfacing between a semiconductor IR detector 23 and associated output electronics 24, 25, 26 which technique and circuits transfer a charge packet onto a sense capacitor 22 that previously stored a reset level signal. The resulting stepped signal change, or delta, in the voltage present on that capacitor 22 is employed as the output signal.
Claims13
An output encoding circuit for an associated IR detector element, the circuit including:
- (1) a first capacitive element;
- (2) means to periodically impose a signal across the first capacitive element proportional to the reset level of an associated infrared detector, so as to initiate a frame interval;
- (3) means to accumulate the output of the associated infrared detector for a frame interval;
- and
- (4) means (a) to readout from the first capacitive element the reset signal level, then (b) to impose on the first capacitive element a signal proportional to the output of the IR detector, and then (c) to readout the IR detector signal on the first capacitive element, these sequential operations (a), (b) and (c) defining a pixel address period substantially less than the frame interval, such that output encoding circuit produces a stepped output voltage representative of the delta change on the first capacitive element during the sequential readout operations for each successive frame interval.
2 more elements
Dependencies are inferred from the claim text.