The History
Wamco began in 1968 as a supplier of high quality subminiature incandescent
lamps to the aerospace, computer and hi-rel electronics industries.
Today we are listed on the Federal Specification QPL WL-00111 and are
a top supplier of subminiature incandescent lamps and DVF displays
to the aerospace industry.
Wamco is noted for high quality products, quick response to new designs,
excellent sales staff, and service which is backed by one of the largest
lamp and DVF display inventories in the United States and Canada.
Wamco’s KW DVF displays were developed
as a result of requests we received from our aerospace customers to
design a truly high quality sunlight readable display capable of withstanding
the most rigorous of environments.
The Factory
Wamco selected Wakoh Corporation in Tokyo, Japan to manufacture our
readouts. Wakoh eagerly accepted the challenge to improve upon the current
DVF technology in the areas we felt were vitally important. We were confident
they would be able to accomplish this task based on their experience
and the research they had already accomplished in the development of
highly innovative and proprietary system for sealing and evacuation.
Superior Features of KW DVF Displays
Non-Crossed
Filaments:
Eliminates potential of filaments accidentally touching (at
the corners) during shock and vibration.
All Glass Package:
Increases reliability during
temperature cycling because of the lack of dissimilar materials at
the sealing seam of the faceplate.
Larger Sealing Area:
Our proprietary sealing
process has eliminated vacuum leaks as a major problem.
Special Filament
Mounting Pads:
Character dimensions are held to a tolerance of plus/minus
.015”.
High Vacuum Level:
Guarantees a longer life
and reduces the tungsten evaporation rate closer to the theoretical
rate.
Greater Filament Strength:
Proprietary processing
and heat treating of Wamco filaments permits them to withstand high
shock and vibration environments. Wamco readout filaments have been
subjected to 50 G’s without breakage,
although we do not recommend their use under these conditions.
Water Cycle
Eliminated:
Special processing eliminates the out-gassing of water
molecules (a phenomena which begins at 100º C +) from the glass which
attacks the tungsten filament and drastically reduces filament life.
Benefits
• Sunlight readable
• Low power
• Night vision goggle readable
• Wide viewing angle
• Directly replaceable to other DVF displays
• Multiplexing
• Impervious to salt spray and humidity
• Even Brightness at rated and
dimming voltages
• Long life
• Withstands temperature extremes
• Compact design
• Withstands transient voltages which damage solid state
devices
• Compatible with LED display IC drivers
• Color filtering
Quality Control
• Production lots coded for traceability
• 100% aging 50 hours before
shipment
• 100% brightness measurement at both rated and dimmed voltages
• 100% selected
for current draw
• 100% production lots are sample tested to special inspection
level "S-4";
lot size "F"; 1.0 AQL in an oven @ 125º C for 15
hours
Brightness
There are two methods of measuring
the brightness of direct view filament displays. The first method yields
candelas, and the second, foot-lamberts. Wamco uses the candela method.
Candelas can be measure very accurately and, more importantly, the
measurements have a high degree of repeatability. Candelas closely
represent what the eye actually sees because it measures integrated
light from all of the filament coils.
The history of measuring the brightness
of filament displays in foot-lambert values has not offered a high
degree of reliability. Accuracy is suspect and the repeatability
of measurements is difficult. Foot-lambert measurements do not
reflect what the eye sees because the photometer focuses on only a
few filament coils. The only advantage of having foot-lambert values
is to compare for equal brightness readouts of different sizes.
