With Invisage technology making so much noise recently, I tried to understand what they really achieved looking at the patent applications. So far I was able to find only two of them published.
US2009152664 published only at European PO site (but not at USPTO site) is an impressive document: it has 218 pages, 99 pages with figures. A same or similar patent is filed as PCT WO/2008/131313 (nice number) has an impressive list of 25 inventors, including Keith Fife, and appears to be a combination of few US provisional patents. Another application is US20100044676 of more modest size of 46 pages with many performance graphs.
The two application have a lot of data and possibly can shed some light on the sensor operation and performance. Here is what I was able to grasp in some limited time:
First, the pixel schematic seems to be a regular 3T structure:
2, CuInSe2 and Cu(GaIn)Se2 quantum dot materials. Multi-layered Foveon-like sensors are also described in great details - this can be a real advantage if Invisage is able to make such sensors:
Said all this, I still have some reservations about suitability of photoconductor principle for consumer photography applications. The problem is that in comparison with photodiodes, photoconductors have an additional and potentially significant noise source - recombination process. Photodiodes are simple devices in that respect - once the photocarriers are generated they are pulled apart by electric field and by this the detection process ends. Photoconductors, on the other hand, are infinitely more complex - the photogenerated carriers just give start to a long and complex process which ends with their eventual recombination. The recombination, being a random process, adds its component to the shot noise of the sensor.
Now, assuming recombination noise is about the same as photogeneration shot noise, photoconductors have an innate disadvantage in SNR10 figure: for the same QE, color crosstalk and very low dark noise, photoconductors have twice worse SNR10 figure. For that reason alone I doubt photoconductive devices can compete with photodiode ones, not in consumer imaging, anyway.