2
Contrast Enhancement
The objective of contrast enhancement is to provide good
displayreadabilityintheenduseambientlight.Theconcept
is to employ both luminance and chrominance contrast
techniquestoenhancethereadability.Thisisaccomplished
by having the OFF dots blend into the display background
and the ON dots stand out vividly against this same back-
ground. Therefore, these display devices are assembled
with a gray package and matching encapsulating epoxy
in the dots.
Contrast enhancement may be achieved by using one of
the following suggested filters:
Standard Red and AlGaAs Red (HDSP-5300/H150)
Panelgraphic RUBY RED 60
SGL-Homalite H100-1605 RED
3M Louvered Filter R6610 RED or N0210 GRAY
HER (HDSP-5500)
Panelgraphic SCARLET RED 60
SGL-Homalite H100-1670 RED or H100-1250 GRAY
3M Louvered Filter R6610 RED or N0210 GRAY
Yellow (HDSP-5700)
Panelgraphic YELLOW 27 or GRAY 10
SGL-Homalite H100-1720 AMBER or H100-1250 GRAY
3M Louvered Filter A5910 AMBER or N0210 GRAY
Green (HDSP-5600)
Panelgraphic GREEN 48
SGL-Homalite H100-1440 GREEN or H100-1250 GRAY
3M Louvered Filter YG6610 RED or N0210 GRAY
For further information on contrast enhancement please
see Application Note 1015.
Mechanical
Specially developed plastics are used to optimize the
displays optical performance. These plastics restrict the
solvents that may be used for cleaning. Only mixtures of
Freon (F113) and alcohol should be used for vapor clean-
ing processes. Total immersion time in the vapors is two
minutes. Some suggested mixtures are Freon TE, Arklone
A or K, or Genesolv DI-15 or DE-15. A 60°C (140°F) water
cleaning process may also be used. This process includes
a neutralizer rinse (3% ammonia solution or equivalent),
a surfactant rinse (1% detergent solution or equivalent),
a water rinse, and a thorough air dry. Room temperature
cleaning may be done with Freon T-E35 or T-P35, Ethanol,
Isopropanol, or water with a mild detergent.
Cleaning agents from the ketone family (acetone, methyl
ethyl ketone, etc.) and from the chlorinated hydrocarbon
family (methylene chloride, trichloroethylene, carbon
tetrachloride, etc.) are not recommended for cleaning
LED parts. All of these various solvents attack or dissolve
the encapsulating epoxies used to form the package of
plastic LED parts.