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CS2 Color Scanner
General Application Information
The term "color" actually inplies visable light --
wavelengths from about 400 nm (violet) to about 750 nm
(deep red), although in this document any color that can
be seen by the CS2 is refered to as a color.
With high intensity LEDs available at 450nm (blue) and at
a variety of wavelengths up to 700nm, the CS2 can see all
of athese colors. But the CS2's capability does not stop
there; the precision silicon photodiodes in the CS2 can see
into the near-infrared (NIR) up to about 1,000nm, and
LEDs are readily available in this region as well.
NIR LEDs are used in the CS2 and similar scanners for
several different functions. One involves using the NIR
reading to establish a baseline value that is constant (or
nearly constant) regardless of the visible color of the
product.
For example, to detect "browness" on cookies, any one of
several visable colors can be used. But using one color
(monochromatic) and looking for changes in amplitude
will not produce good results, since other factors, such as
dirty optics, temperature changes, etc., can produce
signals that are indistinguishable from "browness"
changes.
However, using the ratio of a visable color to an NIR
color will give the desired result: the ratio will only
change with product color, not with ambient conditions.
Other uses of the NIR spectrum include sorting items that
can be differentiated in the NIR spectrum. Delta's CS-
plus-T50 tomato sorters, for example, uses two different
NIR colors to differentiate tomatoes and virtually any
other item.
Delta's LGM length graders use monochromatic NIR light
to detect product presence only. They function as
reflective light curtains and detect products regardless of
visable color. The viewing area is very long and narrow
allowing the LGM to cover an area approximately two
inches in diameter at about six inches from the scanner.
The LGM measures product length at 1/32 inch resolution
at speeds of 550 ft/min.
Delta Computer Systems, Inc., 11719 NE 95th Street, Vancouver, Washington 98682-2444 (360) 254-8688
email@deltacompsys.com http://deltacompsys.com
Here are some examples of items and applications that
Delta has successfully tested:
•
Detecting the presence or absence of brown glue on
brown wood
•
Detecting "browness" of crackers, etc.
•
Detecting green ends on carrots
•
Detecting white ends on asparagus
•
Detecting various defects on potatoes
•
Differentiating between tomatoes and MOT (material
other than tomatoes)
•
Using a modified CS2, differentiating between
several different colors of cloth
•
Using a modified CS2, identifing several different
colors on a cardboard box
•
Some of these applications are in use, and some
remain in testing. More tests are done on a regular
basis.
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