Patent ID: 6683645
Filing Date: 2004-01-27
Classification: H01L,H04N

Abstract:
A method of correcting for device variations in an imaging system, said system incorporating:(i) detecting means (52) comprising multiple detector elements (56) arranged to detect electromagnetic radiation from a scene and to generate pixel image signals in response thereto; (ii) processing means (58) arranged to high-pass spatially filter the pixel image signals and to generate processed output image signals having a dynamic range which is less than that of radiation from the imaged scene, the processing means being spatially separate from the detecting means (52); and (iii) floating gate device compensating means (118, 278) for compensating for errors arising from variation in the characteristics of circuit elements incorporated into the detecting means (52); â€ƒthe method comprising the steps of (a) resetting the floating gate device compensation means by exposing it to ultra violet radiation to remove charge stored therein; (b) exposing the detector elements to a uniform intensity of radiation from a scene; (c) selecting an element and comparing its pixel image signal with a respective desired output signal; (d) injecting charge into the floating gate device means to adjust its characteristics so that the pixel image signal is substantially equal to the desired output signal; (e) repeating steps (c) and (d) until all elements in the system have been corrected.