Saturday, January 31, 2009

Weekly Patent Review

The most interesting application of this week is Kodak's US20090021612. It attempts to overcome the new WRGB-colored sensor problem of early signal overflow in panchromatic pixels. The multiple readout curtains are arranged in such a way that panchromatc pixels get shorter exposure time than colored ones. Then, generalizing the idea, Kodak proposes a readout scheme with different exposure times per each color, as on the figure below:



My first concern about this idea is different motion artifacts for different colors, if fast moving objects are photographed or in presence of camera shake. It might require a good deal of image processing to conceal these artifacts. The second concern is a more difficult wiring of the pixel array, which might result in lower fill factor - can be resolved, if made in BSI.

TSMC patent application US20090020838 proposes to use black photoresist rectangles between the neighboring pixels under color filter to reduce crosstalk. I don't think the idea is new, but there might be some new trick in the manufacturing process of the rectangles.

1 comment:

  1. Actually, I think US20090021612 was designed with BSI in mind. In addition to letting more light in, BSI also offers more layers for circuitry. I think the Omnivision chip has four layers, plus you get the whole chip area instead of just around the edges.

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