Photosensitive apparatus in which an initial charge on a photodiode is sampled and the retransferred to the photodiode
AssigneeXerox Corporation
InventorsPaul A. Hosier, Jagdish C. Tandon
Life of this patent
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Abstract
In a photosensitive device wherein a photodiode 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 and thermally-induced noise is obviated.
Claims7
A method of operating a photosensitive apparatus having at least one photodiode and a storage means associated with the photodiode, comprising the steps of
- injecting a charge on the photodiode;
- transferring the charge from the photodiode to the storage means;
- retransferring the charge from the storage means to the photodiode;
- integrating a light signal on the photodiode;
- and
- reading the charge and the light signal from the photodiode through the storage means.
Dependencies are inferred from the claim text.