OPERATION METHOD OF PHOTOSENSOR IN WHICH INITIAL CHARGE ON PHOTODIODE IS SAMPLED AND THEN RETRANSFERRED TO THE PHOTODIODE

摘要

PROBLEM TO BE SOLVED: To obviate fixed-pattern noise and thermally-induced noise in photosensitive device employing fat zero charges. SOLUTION: In the photosensor wherein a photodiode 10 is operated by placing an initial fat zero charge thereon before the integration of a light- induced signal, the actual dark level signal created by the fat zero charge is sampled with each readout from the photodiode, and then retransferred to the photodiode. After integration, the sampled dark level is subtracted from the total signal level on the photodiode. In this way both fixed-pattern noise and thermally-induced noise are obviated.