Smear reduction technique for CCD field-transfer imager system

摘要

Three embodiments of an improved smear reduction technique, for reducing substantially all the smear in a CCD field-transfer imager system due to the presence of a bright spot in the projected image, regardless of whether the bright spot remains fixed or whether the bright spot moves between successive field periods. Prior smear reduction techniques were not effective with respect to a moving bright spot. Structurally the improved system employs a CCD field-transfer imager including a line register, in addition to conventional A and B, for collecting smear charge produced in the A register during each successive field period. The smear line register cooperates with associated circuitry to provide the improved smear reduction. In a first and second of the three embodiments, the imager includes a conventional C line register for deriving a smeared video output applied as an input to the associated circuitry, and the smear line register is an additional line register, known as the D register. In a third of the three embodiments, the conventional C register is omitted and a single line register, known as a C-D register, performs the functions of both the C and D line registers in the first and second embodiments.