[Leica]Digital Photography(slightly OT)

["Andrew S Jordan" <andrewsjordan@worldnet.att.net>]

For you digital photo enthusiasts, the latest research development - fresh
from the annual semiconductor device conference- is attached.

regards, Andrew Jordan



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Philips CCD rivals 35-mm quality
By Peter Clarke, EE Times
Dec 9, 1999 (9:04 AM)
URL: http://www.eetimes.com/story/OEG19991209S0012

WASHINGTON — Digital still cameras could rival the image quality of 35-mm
film photography within a couple of years due to a charge coupled device
(CCD) image sensor with over six million pixels developed by Philips
Semiconductors (Eindhoven, Netherlands). Herman Peek, a senior scientist at
the company, presented a paper on the prototype device at this week's
International Electron Devices Meeting. "This is the largest number of
pixels and the smallest pixel size for a digital still camera ever published
in the world," Peek said during the presentation of his paper.

Although the prototype sensor is monochrome, and the use of red, green and
blue filters would reduce resolution to 2 million tricolor pixels, Peek said
the small size of individual light sensing elements, 3-micron x 3-micron,
would allow such a sensor to rival small format film photography.

"We are approaching the grain size of film, which is about 2 microns
diameter, but image quality is also determined by the quality of the lens.
The same thing effects CCD."

Images produced using the sensor and displayed by Peek, albeit through an
overhead projector system, were indistinguishable from images obtained from
film. Individual hairs could been seen on the heads of head-and-shoulder
portraits, which prompted congratulations from the audience.

Peek said he expects to see a similar high-resolution CCD sensor in
production within about two years, although it might include fewer pixels.
"I don't think we will go to more pixels," he said. "We are already asking,
'Is six million too much and are we adding cost unnecessarily?' Perhaps five
million or four million is the right amount."

For a 2/3-inch format, Peck showed that the pixel size was on the limit of
lens resolution, although the device could also be used for lens-less
applications.

The Philips CCD is built using a 0.5-micron CCD process operating at 14
volts and has an active area of 2,048 active lines and 3,072 active
measuring 9.11 mm x 6.07 mm. The sensor has a dark current of 800
picoamperes/centimeter2 and a dynamic range of 63 dB. In his paper, Peek
also discussed how novel techniques had been used to overcome problems with
dark current suppression.

The development of a high-resolution sensor using CCD technology represents
a fight back by the technology against a challenge it faces from lower cost
CMOS image sensors, which also allow the possibility of including signal
processing and logic circuits on the same die.

"CCD will always be expensive in comparison with CMOS image sensors," Peek
said. "CCD can't compete with CMOS on price but it can on quality, and image
quality is very important to consumers."


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