HDSP2110S Datasheet, PDF (13/13 Pages) Infineon Technologies AG – 8-Character 5x7 Dot Matrix Parallel Input Alphanumeric Intelligent Display

Optical Considerations
The .200" high character of the HDSP211XS gives readability up
to eight feet. Proper filter selection enhances readability over
this distance.
Using filters emphasizes the contrast ratio between a lit LED
and the character background. This will increase the discrimina-
tion of different characters. The only limitation is cost. Take into
consideration the ambient lighting environment for the best
cost/benefit ratio for filters.
Incandescent (with almost no green) or fluorescent (with
almost no red) lights do not have the flat spectral response of
sunlight. Plastic band-pass filters are an inexpensive and effec-
tive way to strengthen contrast ratios. The HDSP2110/2112S
are red/high efficiency red displays and should be matched
with long wavelength pass filter in the 570 nm to 590 nm
range. The HDSP2113S should be matched with a yellow-
green band-pass filter that peaks at 565 nm. For displays of
multiple colors, neutral density grey filters offer the best com-
promise.
Additional contrast enhancement is gained by shading the dis-
plays. Plastic band-pass filters with built-in louvers offer the
next step up in contrast improvement. Plastic filters can be
improved further with anti-reflective coatings to reduce glare.
The trade-off is fuzzy characters. Mounting the filters close to
the display reduces this effect. Take care not to overheat the
plastic filter by allowing for proper air flow.
Optimal filter enhancements are gained by using circular
polarized, anti-reflective, band-pass filters. The circular polar-
izing further enhances contrast by reducing the light that
travels through the filter and reflects back off the display to
less than 1%.
Several filter manufacturers supply quality filter materials.
Some of them are: Panelgraphic Corporation, W. Caldwell, NJ;
SGL Homalite, Wilmington, DE; 3M Company, Visual Products
Division, St. Paul, MN; Polaroid Corporation, Polarizer Division,
Cambridge, MA; Marks Polarized Corporation, Deer Park, NY,
Hoya Optics, Inc., Fremont, CA.
One last note on mounting filters: recessing displays and bezel
assemblies is an inexpensive way to provide a shading effect in
overhead lighting situations. Several bezel manufacturers are:
R.M.F. Products, Baklava, IL; Nobody Components, Griffith
Plastic Corp., Burningly, CA; Photo Chemical Products of Cali-
fornia, Santa Monica, CA; I.E.E.-Atlas, Van Nuys, CA.
 2000 Infineon Technologies Corp. • Optoelectronics Division • San Jose, CA
www.infineon.com/opto • 1-888-Infineon (1-888-463-4636)
OSRAM Opto Semiconductors GmbH & Co. OHG • Regensburg, Germany
www.osram-os.com • [phone]
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HDSP2110S/1S/2S/3S/4S/5S
March 24, 2000-13