Monday, February 03, 2014

Sony Applies for Nano-Carbon Film IR Shutter Patent

Japanese language Egami blog noticed Sony patent application proposing to use nano-carbon film that apparently changes its transparency with applied electrical field. It looks like the transparency is modulated only in IR band, but Sony considers it significant enough to apply for an IR shutter patent.

7 comments:

  1. Looks like the nano-carbon filter can cut off almost all light when no voltage is applied.
    Here is from machine translated text from the patent itself
    [0062]
    [About a noise cancellation function]
    Next, the noise cancellation function which corrects dark current unevenness is explained in full detail. Dark current is a noise generated by the electric charge generated with output current or heat, even when light is intercepted completely. In giving a noise cancellation function to the solid state image pickup device 11, as the nano carbon cascade screen 35, the transmissivity of the light when not applying voltage is about 0%, and the transmissivity of the light at the time of applying voltage uses the nano carbon cascade screen which is about 100%. In this case, when not applying voltage to the nano carbon cascade screen 35, in order that IR pixel 39IR may not transmit light, the signal component obtained is only noise component deltaE by dark current. The noise signal by dark current is removable by each pixel by deducting the noise by this dark current from each signal component of the red picture element 39R, the blue pixel 39B, and the green picture element 39G.

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  2. I think that the real utility of this device is to permit an estimation of IR component. For a surveillance camera, you have to switch the IR-cut filter to be able to operate the camera in Day/Night mode. With this device, you can have an estimation of the IR component in color processing without IR-cut filter. A great simplification and possible new applications.

    -yang ni

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  3. The data shown above shows modulation between 97.6% and about 100%. Am I reading this wrong? If this is the modulation depth then I think this is not anything to be excited about yet.

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    Replies
    1. This is my understanding too. I do not think it's worth patenting, unless Sony sees a possibility for big improvement in transparency.

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    2. It's said that 40 layers laminated structure is applied as shutter, so transmittance of visible becomes about 8%(1-2.3*40).

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  4. if it's for NIR component estimation, this shallow modulation depth should be enough. I don't think that they work on pyrelectric type thermal detectors.

    -yang ni

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  5. My guess is that the real purpose of this patent is to allow x-sync at any speed. Imagine a camera with no shutter at all. When you press the "shutter" button the sensor stay sensitive for 1/125 or 1/8000. There's no x-sync limits anymore.

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