Wednesday, November 16, 2011

Fujifilm Organic Pixel Patented

Fujifilm organic pixel patent US8053661 has been granted recently. The patent is named "Photoelectric conversion element and imaging device" and talks about the sense layer chemistry and the pixel structure:

"In an organic photoelectric conversion element, for realizing high photoelectric conversion efficiency, low dark current and high-speed responsivity, the organic photoelectric conversion layer used preferably satisfies the following requirements.

1. In terms of high efficiency and high-speed response, the signal charge after dissociation of an exciton needs to be swiftly transmitted to both electrodes without loss. High mobility and high charge transport ability with a small number of carrier trapping sites are necessary.

2. In terms of high photoelectric conversion efficiency, it is preferred that the exciton stabilizing energy is small and the exciton can be swiftly dissociated by the effect of an externally applied electric field or an electric field generated in the inside by pn-junction or the like (high exciton dissociation efficiency).

3. In order to reduce as much a carrier generated in the inside at dark time as possible, it is preferred to select the intermediate level in the inside and select a layer structure and a material that allow the presence of less impurities working out to one of causes thereof.

4. In the case of stacking a plurality of layers, an energy level matching with the adjacent layer is required and if an energetic barrier is formed, this inhibits charge transport.
"

The patent has description of chemical composition of photosensitive and electron- and hole-blocking layers and also shows the 3T-like pixel schematics:


Thanks to DI for sending me the patent!

7 comments:

  1. Seems that the patent is follow up to this paper - http://www.fujifilm.com/about/research/report/055/pdf/index/ff_rd055_004_en.pdf

    ReplyDelete
  2. Considering how interesting this inventon is to a layman and the not yet introduced, but confirmed Fuji high-end (rangefinder?) camera, awfully little discussion here on this technology ;)

    The earlier paper seems to indicate a rather large full well capacity for relatively small pixel.

    Also, if I understood the patent properly, each pixel consists of vertical set of three photoelectric conversion element layers, ie. kind of organic version of Foveon, with none of the color issues, similar high read noise, and good responce to angular incident light?

    ReplyDelete
  3. Full Colour Image Capture
    Low Noise
    No AA Filter
    No Green Cast
    High Resolution
    High Dynamic Range
    FANTASTIC IQ

    Please please please please...........

    ReplyDelete
  4. @Anonymous
    "if I understood the patent properly, each pixel consists of vertical set of three photoelectric conversion element layers, ie. kind of organic version of Foveon, with none of the color issues, similar high read noise, and good responce to angular incident light?" --- I think you are incorrect, the paper points to individual pixels for R, G and B each, with color filters delineating each type.

    ReplyDelete
  5. To the other Anonymous:

    I was referencing to the *patent*, not to the research paper. To me the patent is clear on this, but I am no expert.

    To me, in the research paper the color filter diagram seems speculative as the chip they built has no color filters.

    ReplyDelete
  6. Link to the patent:

    http://www.freepatentsonline.com/8053661.pdf

    ReplyDelete
  7. The patent covers three variants, no filter, three adjacent pixels, and a true color in depth pixel.
    I don't think they will implement the foveon like sensor in the first iteration. It's a wishful thinking that this sensor will end in the coming Fuji LX camera.

    ReplyDelete

All comments are moderated to avoid spam.