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Ever Wonder What Goes into the Design of LED Retrofits?
May 1, 2014
Author: Arun Dutta, Director of LED Lamp Development for the Americas and Head of Wireless Lamp Development, OSRAM SYLVANIA
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​It’s no secret that complex interactions take place in a quality LED retrofit lamp, and all consumers need to do is just screw the lamp in and enjoy the light for a very long time.

Alright, so let’s break down the design. In a LED retrofit lamp, it is the light engine comprised of LEDs (discrete or chip on board) that emits the light that you see. The LEDs in the lamp operate at a temperature much higher than ambient, resulting in lower lumens. This thermal efficiency factor lowers the lamp efficacy (lumens per Watt or LPW) below that of the intrinsic LEDs. Depending on the application, some LED lamps also have a form of secondary optics to shape the pattern of the light. However, not all the light emitted by the LEDs makes its way out of the lamp. There is a light extraction efficiency associated with the whole optical system and this also lowers the efficacy of the lamp below that of the intrinsic LEDs. Finally, there is a driver efficiency factor (not all of the input power to the lamp ends up being delivered to the LEDs) which again reduces the lamp efficacy. It is the product of these three individual efficiencies which gives the overall factor to help the designer determine the final lamp efficacy.

Very interesting, right? Want to learn more on what goes into the design of LED retrofit lamps? Check out my full blog post online in LED Journal for more details.