Sony: New 6mpix CCD imager!
By
Mike Tomkins
(Saturday, February 16, 2002 - 19:43 EST)
ICX413AQ CCD sensor looks to be aimed at digital SLRs...
Sony is working on a new 6 megapixel CCD image sensor, the ICX413AQ, our friends at the Digital Photography Review website hear from a reader. According to a Sony development document we've read, the ICX413AQ is a primary color CCD that has a diagonal of 28.4mm (1.12in) and an active area of 3032 x 2016 square pixels - or 6.11 megapixels. With a chip size of 25.10 x 17.64mm and active area dimensions of 23.65 x 15.72mm, it is close - but not identical - to APS C film which is 23.4 x 16.7mm. (APS C has an aspect ratio of 1.4:1, whilst the larger APS H is 1.8:1). This isn't the whole story though, as explained in a couple of paragraphs.
The sensor is an interline transfer frame readout type - which means that the contents are read off the imager line by line, and that the entire contents of the frame must be read out (as opposed to partial contents, which can be done with CMOS imagers - not to be confused with a frame transfer imager, where the readout area has the same dimensions as the imaging area, and the entire contents are read out in one go). It is designed for use with a mechanical shutter to prevent smear, but without one has a smear level of -80dB. It also has a fairly fast full-frame rate of 3.08 frames per second - not up to the speeds of Canon's EOS-1D or Nikon's D1X cameras, but certainly fast enough to hold its own amongst the low to mid-end digital SLRs.
The sensor itself has dimensions of 3110 x 2030 pixels (6.31 megapixels), of which 70 columns and 8 rows are blacked out for dark-current calibration, etc. - leaving 3040 x 2024 pixels effective in image interpolation. A further 4 pixels on all sides of the image are discarded as, whilst they contain information to interpolate color values for other pixels, they lack sufficient partners to interpolate color values for themselves. Hence, the result is a 3032 x 2016 pixel image. Curiously, this is apparently cropped once more as a function of the imager to a 3:2 aspect ratio (similar to 35mm film), as Sony lists the "number of record pixels" as 3000 x 2000. This affects the diagonal of the imager somewhat though, since the diagonal is quoted as the dimensions active before this cropping takes place!
All very complicated, but suffice to say by our math the final area of the sensor used in the image is 23.4 x 15.6mm - the same width as APS C, but not quite as high. The diagonal of this area is 28.1mm, which would lead to a focal length multiplier of 1.54:1 if using 35mm lenses. The cell size (distance from the center of each pixel to the center of its neighbor, either horizontally or vertically since the imager uses square cells) is 7.8μm.
The Digital Photography Review notes an expected date of June 2002 for mass production, with no mention as yet to pricing. This looks like a suitable chip for use in a low to mid-end digital SLR, and we'll await confirmation of pricing with interest! Further provisional specifications can be read here.
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