A twin-channel (p and n) FT-CCD imager with cross-antiblooming

A new class of Frame-Transfer CCD image sensors is presented, which is based on the use of both electrons and holes as information carriers and has a novel cross-antiblooming structure for overexposure protection. The device consists of alternate columns of p- and n-channel CCD's, which form two separately operating p and n imagers. This concept is based on the use of the n channel as a channel isolator for the p channel and vice versa and has five advantages. First, the complete area of the image section is active because no light-insensitive channel stop area is required. Secondly, both generated carriers electrons and holes can be stored and transported simultaneously. Thirdly, in a typical four-phase clocking system the electron pixels and the hole pixels are separated by half a pixel pitch in both the vertical and horizontal directions, which improves the pixel-packing density and aliasing suppression. Fourthly, the pattern also forms a line-quincunx sampling grid, which offers many advantages for signal processing, especially as the p- and n-output signals are simultaneously available. Finally, this pixel configuration is also ideally suitable for realizing a progressive-scan imager and a color imager.