Basic
/ Transition
of Incandescent to LED technology on the Flight Deck
IDD Design
and Test Capabilities /
Design
and Production
What are the advantages
of LED lighting over incandescent lighting?
- More Uniform Lighting
- Higher Reliability (MTBF of Incandescent
Lamps vs. MTBF of LED Lamps – see chart below)
- Reduced Service Cost (Due to magnitude
greater LED MTBF, lamp replacement is infrequent or unlikely during
the life of the aircraft)
- Lower Power Consumption
- Automated assembly process via surface
mount reduces production costs.
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Electroluminescent |
Incandescent |
LED |
Useful Life |
8,000 hours |
100,000 hours |
500,000 hours |
MTBF |
8,000 hours |
23,000 hours |
300,000+ hours |
Cost |
1 |
0.8 |
0.95 |
Power |
1.00 Watt |
5.40 Watts |
.40 Watt |
Surface Temperature |
78°F |
110°F |
78°F |
Repairability |
Not Repairable |
Lamps Replaceable |
Lamps Replaceable |
Weight (Not including
any additional weight as a result of 115 volt inverter) |
100 g |
95 g |
95 g |
Thin Profile |
.120” |
.180” |
.180” |
What is the difference
between the lighting curve for Incandescent and LED panels?
An incandescent lamp becomes brighter as
a non-linear function of its input voltage. The approximate function
is B = V 3.5 for a non-gas filled incandescent lamp. Where B is
brightness and V is input voltage. This is referred to as an “incandescent
dimming curve”.
Can an LED panel
be installed in an incandescent environment?
IDD designs and builds LED panels for both
LED and existing Incandescent flight deck installations. On newer
model aircraft, LED installations are standard and generally use
a 28 volt input and have a linear dimming curve.
To achieve uniformity of lighting in an incandescent
flight deck installation when installing a co-located LED illuminated
panel within an existing incandescent panel environment, the brightness
of the LED illuminated panel must adapted to achieve uniform cockpit
lighting. To accomplish this the dimming control input is transformed
to a Pulse Width Modulated (PWM) control waveform whose duty cycle
follows the “incandescent dimming curve”.
An example of an incandescent dimming curve
and actual measured LED illumination in IDD products is shown below:
What options exist
for the control of LED illumination in the cockpit?
- Brightness control via an analog
dimming control voltage.
The dimming control voltage (DC or AC)
from the aircraft to the light plate or control panel is conditioned,
a dimming curve is implemented to approximate an incandescent
dimming curve, and the brightness of the LEDs is controlled based
on the input voltage and dimming curve transfer function. The
circuitry can derive its power exclusively from the dimming control
voltage if alternate power busses are not available.
- Brightness control command via the
communication interface.
The brightness can be commanded
as a percentage of full scale brightness from a command label
via a digital communication interface.
- Brightness control from a PWM dimming
control unit.
The LED illumination brightness can be
controlled by an external PWM dimming control unit either directly
sourcing the LED current or providing a low current PWM waveform
that drives current control circuitry on the light plate or control
panel.
IDD provides solutions for each of the above illumination scenarios.
Is there a cost impact
when implementing LED lighting?
When LED was first introduced to the aviation
market in the early to mid 1990s, the volumes were lower and it
was a newer technology. This led to a higher cost when compared
to incandescent or electroluminescent technology. As the technology
matured and the volume increased the cost differential between incandescent
and LED lighting, continued to decrease. The technology continues
to be adopted because additional acquisition cost is off-set by
the order magnitude improvement in aircraft life-cycle costs. This
includes the higher reliability in Mean Time Between Unplanned Removal
(MTBUR) and Mean Time Between Failure (MTBF) of LED illumination
when compared to incandescent lamp installations. An additional
benefit of LED technology that continues to hold down costs, is
that LEDs are surface mountable which enables automated assembly
and reduced labor time in some applications.
IDD currently produces over 200 part numbers
of LED parts. New LED flight decks with over 30 IDD lightplates,
keyboards and control panels include the Embraer 170/190, the Bombardier
Challenger 300 and the Airbus A380. IDD consumes over 10,000 LEDs
per month in the production of LED panels. Due to the large volume
and optimized production processes, the prices of LED illuminated
panels and keyboards produced by IDD are often the same cost or
less than incandescent keyboards and panels.
How does IDD manage
fluctuation in brightness from LED suppliers in the industry?
Commonly in the aviation industry, technology
is not driven by the specialized demand of the aviation industry.
The volumes required in aviation applications are too low to entice
LED manufacturers to meet the tighter specification ranges and continue
production of a set specification for many years. In this case,
LED technology for the world market continues to improve in brightness
and the lighting output can change from lot to lot.
IDD has developed an internal process to
monitor and address these changes and continue to meet design specifications.
These processes ensure that customers can order product from IDD
years after the development and that the product continues to meet
the specification regardless of the evolution of LED technology.
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