At 11:48 PM 05/14/2001, you wrote:
>Price, on the other hand, is definitely an advantage. That's why CMOS
>sensors are used in all the cheap cameras.
From the NYTimes Circuits Section of May 10, 2001:
Blinc is one of a number of digital imaging devices based on the
relatively new
complementary metal oxide semiconductor, or CMOS,
technology. Several
companies, including Sarnoff, Eastman Kodak, Foveon and
Intel, are promoting
CMOS as a replacement for the charge-coupled devices, or
C.C.D.'s, that are
currently found in most digital video and digital still
cameras.
"The C.C.D. was a great invention," Mr. Andreas said, "but
it does have a lot of
limitations."
One of the chief advantages of CMOS cameras is that they
directly produce digital
images. C.C.D.'s, by contrast, yield an analog image, which
then must be
transformed by digital processing. That step adds costs and
drains batteries of
portable devices. That and other power savings may one day
make CMOS
cameras suitable for use in wireless phones and other
gadgets whose batteries are
already undersize and overworked.
CMOS chips can also be produced in the same factories that
make conventional
computer chips. Because of that, all the electronics for the
CMOS-based camera
can be built into the senior chip at the time of its
creation. Such camera-on-a-chip
designs cut both the overall size and cost. C.C.D.'s, by
contrast, must be
manufactured using a special process and then combined with
the chip containing
their electronics.
While Kodak and others were emphasizing image sharpness in
their CMOS chips,
Sarnoff's researchers were more concerned with its dynamic
or exposure range.
Integrated in Blinc's imaging chip is software that controls
the exposure range of
each pixel. The result, by Sarnoff's measurements, is a
camera that has 100 times
the dynamic range of a typical C.C.D. unit.
Among other things, said Niel McCaffrey, head of Sarnoff's
Advanced Imaging
Unit, that broad sensitivity eliminates the need for a
mechanical aperture within the
camera's lens to increase or reduce the amount of light that
reaches the sensor chip.
Such apertures take time to adjust, and their motors draw
substantial amounts of
power.
--
regards,
Henry Posner
Director of Sales and Training
B&H Photo-Video, and Pro-Audio Inc.
http://www.bhphotovideo.com
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