Since the introduction of LED technology into the general illumination lighting market, one desired feature has been the
ability to replace the luminaire lamp in a similar manner to conventional sources (e.g. screw or plug in). Due to thermal
management issues, successfully implementing this feature has proven difficult with many manufacturers simply
integrating the LED sources into the luminaire. However, there are LED replacement lamp products on the market that
manufacturers claim to be the equivalent of their conventional source counterparts. This paper will examine the
relationships between lifetime, light output, source efficacy, thermal management and physical size for three common
lamps: the MR-16, the A-19 (standard incandescent shape) and the PAR-38 (standard floodlight shape). The author will
evaluate the physical size envelope for the three lamp types. Next, a theoretical model for maximum thermal dissipation
to ambient will be determined. Then using data from LED manufacturers, junction temperature limits versus lifetime
will be evaluated and used to determine maximum input power. This input power limit combined with manufacturer's
data and assumed optical and electrical losses will be used to evaluate potential light output of the lamp and compared to
conventional lamp outputs. Upper limits for light output will be determined.
There are many advantages that LEDs offer for use in general illumination. The use of LEDs in certain applications can provide improved energy efficiency. For example, in traffic lights in the United States, LED technology has taken over the market not only because of the energy savings as compared to standard incandescents, but also because of the reduced maintenance costs associated with bulb replacement and improved reliability. With useful lifetimes exceeding 40,000 hours or more, today's high flux LEDs can provide illumination solutions with replacement periods of 8 to 10 years or more. This paper will examine a bridge roadway lighting feasibility study which the authors' company recently undertook. The application required the LED units to reproduce the photometric performance of 64-inch (1.625m) fluorescent lamps. In addition, the LED units were required to survive a harsh, outdoor marine environment with an expected lifetime of 7 years or more. To achieve these results, a number of design elements were studied including: optimum heat dissipation in a sealed enclosure, ease of installation, and design of power supplies having expected lifetimes to match the LED light engines. Results of these studies will be discussed as well as illustrations of the designs chosen.
Since the introduction of the Americans With Disabilities Act in 1990, the number of visual fire alarm signals installed in the United States has grown exponentially. Virtually all of these fire alarm visual signals consist of the Xenon gas flashtube type. This technology offers high intensity along with moderate cost in a relatively small package. Typical intensities offered range from 15cd (candela) up to 185cd. With the recent advances in solid state LEDs (Light Emitting Diodes) the possibility exists to develop visual fire signals using this technology. When used in lower intensity visual appliances, LEDs offer comparable light output with much smaller optical footprints (albeit at somewhat higher estimated costs). This paper will examine the optical performance of a prototype LED visual fire signaling appliance as compared to a more conventional device. It will also evaluate a series of tests, which were run in an office environment to compare the response time of workers for both the conventional Xenon fire signal appliance as well as the prototype LED device. Measurements for each test subject were taken over a two to three day period. Parameters measured included time of day, size of office and general ambient lighting. Results of these experiments indicate that the general response times of the test subjects were similar for the two types of fire signals. The paper concludes with a discussion of the potential for LED-type fire signaling devices as well as some of the potential technology obstacles still to be overcome.
Conference Committee Involvement (8)
Sixteenth International Conference on Solid State Lighting and LED-based Illumination Systems
9 August 2017 | San Diego, California, United States
Fifteenth International Conference on Solid State Lighting and LED-based Illumination Systems
31 August 2016 | San Diego, California, United States
Fourteenth International Conference on Solid State Lighting and LED-based Illumination Systems
12 August 2015 | San Diego, California, United States
Thirteenth International Conference on Solid State Lighting and LED-based Illumination Systems
20 August 2014 | San Diego, California, United States
LED-based Illumination Systems
26 August 2013 | San Diego, California, United States
Twelfth International Conference on Solid State Lighting and Fourth International Conference on White LEDs and Solid State Lighting
13 August 2012 | San Diego, California, United States
Eleventh International Conference on Solid State Lighting
22 August 2011 | San Diego, California, United States
Tenth International Conference on Solid State Lighting
2 August 2010 | San Diego, California, United States
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