Wednesday, October 03, 2012

Sony Applies for a Curved Sensor Patent

Ubergizmo quotes Japanese-language Egami blog (via Google translation) describing a recently published Sony patent application on a method to create a curved image sensor surface. I was unable to find the original patent application link, so the only available info is what's published by Egami:


According to the Egami post, Sony proposes to control curvature by varying the magnetic force, volumetric shrinkage of the base due to heat, or by changing a vacuum suction force. Sony says that one needs to leave a flat portion of silicon around the curved one to avoid cracks.

15 comments:

  1. off-topic but perhaps Vladimir can honor this with a separate post: http://mashable.com/2012/09/26/iphone-5-purple-haze/

    what is causing this? reverse saturation should give a purple sun ...

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    1. Thanks, I've seen these reports, as well as complaints about too long an exposure at low light in comparison with iPhone 4s. I'm not sure it's related to image sensor, though. To me, it has more to deal with iPhone 5 camera algorithms.

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  2. isn't this related to the sapphire glass but not the sensor?

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  3. What are the advantages of such curved sensors.
    Thanks,

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    1. If you can curve it to cancel the "camera" field curvature then you have a cheaper corrected imaging system.

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    2. Yes, but the curve must be the exact shape to match the lens. If not, then parts of the image will be out of focus. So, you need to be sure that not only do you know the shape, but that it is quite reproducible from sensor to sensor (module to module) and stable over time. I think sensor stress due to the forced bending might impact dark current and reliability. (Assuming the radius of curvature is just a few focal lengths.) Thus, I believe all of these things fully negate all advantages of a curved sensor.

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  4. the purple haze is more to do with optics and module design. quite serious considering the army of people in the module team

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  5. the patent publication number is: JP2012182194A

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    1. US equivalent pplication is US20120217606A1

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  6. The purple haze must be related to the use of a dichroic NIR cutoff filter in the camera module, or at least a hybrid dichroic/absorbing NIR filter instead of a purely absorbing NIR cutoff filter.

    Maybe they had to do this to make the module thinner.

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    1. No the purple haze is caused by the lens. It's been seen in this lens on different sensors.

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    2. The IR cutoff filter is usually a part of the lens - coating on a separate glass or on the last element.

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    3. The ir cut has been dichroic for a long time.
      It has some angular depency so cutoff shifts with angle. It can be corrected by SW and wasn't so its probably not the cause.

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  7. It's a stray light reflection off some edge according to a colleague who has used this lens, not the IRCF.

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  8. Hi guys,

    I've just run into the article and I think the curved sensor does totally different thing, correcting discrepancy between photo and human eye's perception. Recently, I myself contacted a patent lawyer with my own idea and he found me this Sony's patent in 3 different countries (as far as we know). In the summary of the patent doc it only talks about how to fabricate the curved sensor but in the main text it implies why they do that only in a couple of lines. This is to help you understand the effect in my words.

    Any photographer must have experienced photos taken with camera get different feel from what s/he sees with human eyes, especially dramatic scenery. Photos or videos of mountain heels always look shorter or less steep than what we see. (Alpine ski slope looks very easy on TV or photo unless taken from side) It's because while human eye ball has concave surface, the camera sensor is flat since the very first film camera and obscura. In comparison to eye's perception the flat sensor does the opposite effect of macro lens which makes objects in short distance look much bigger and those in far distance look much smaller. In other words, with the concave sensor you can make objects in far distance look bigger and that's what human eyes perceive. It's like regular photo images are like the image reflected on convex mirror or backside of shallow spoon when compared to eye perception.

    Well, it cannot be achieved with simple image correction because it's about size ratio between the objects in far and short distances that will be imprinted on the photo image.

    It's funny that the drawing in the patent shows only section but it can be overall concave surface. Also Sony included a line in the patent text that all range of curvatures is to be covered by the patent. It implies that changing curvature is also being considered. Once this becomes available, the effect will be huge. For example, movie maker can get a dramatic effect with the sensor with smaller curvatures, and the face of movie star doesn't have to be small figured. (actors usually have smaller figure than ordinary people because regular size will make the scene look small with when the scene is taken by current camera)

    I was disappointed to see the patent issued for my idea but now I'm itching to see the product sooner. I know that the main element of digital sensor, silicon is now fabricated in flat condition. However, if Sony really can give it curvatures with keeping the consistent material quality, it'll be a huge success. It could affect the entire camera market rewriting the history of photography.

    It's rather about size ratio and composition in the image not image quality.

    If you want more details, let me know. Paul Cha, alekancha@yahoo.com

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