How to Design 120V LED Light Bulbs
Incandescent bulbs are on their way to extinction. Both the European Union and the United States have enacted regulations that ban the manufacture of incandescent lighting by 2014. Incandescent bulbs are inefficient: only about 5 percent of the power they suck in is put out as light. Compact fluorescent bulbs are more efficient, but there's not a whole lot of flexibility in tuning the light they emit. Enter light emitting diodes (LEDs), which offer high efficiency, tunable color and an unprecedented degree of control over the distribution of light. But designing an LED bulb to replace incandescents is a complex process. Does this Spark an idea?
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Instructions
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Familiarize yourself with the U.S. Department of Energy's Energy Star Program Requirements for Integral LED Lamps. The DOE has outlined light distribution, color maintenance, energy efficiency and other requirements for acceptable LED bulbs. If you can't meet those requirements, no one should buy your bulb.
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Perform a design trade-off to select the number of LEDs necessary to reach the desired light output. A single LED might be the optimum solution for managing the light distribution, but it might require such high current that the heat it generates will be unmanageable. Select the mix of white and color LEDs appropriate for your application.
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Design secondary optics to get the light where you want it to be. Optimize the light distribution by modeling the LED layout and the optical surfaces using a nonlinear raytrace program.
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Construct an efficient electronic driver that will convert the 120 volt AC input to the voltage and current you have selected for your LED design.
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Design a thermal management system to keep the LEDs operating well below their maximum rated temperature. This step is absolutely critical, as the lifetime, the color consistency and the overall quality of light will degrade rapidly if the thermal design does not keep the entire package at a consistent, relatively cool temperature.
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Test the LEDs per the Energy Star requirements, and supply data and product samples to the DOE to obtain certification and get your Lighting Facts label.
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Tips & Warnings
The importance of thermal management cannot be overemphasized. Good thermal management will allow higher light output, longer lifetime and better lighting quality. Without good thermal management the rest of the design won't matter.
Nonlinear raytrace programs can be found by searching "illumination design software." There is a wide variety of design packages available; pick the one that meets your needs and your budget.
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Resources
- Photo Credit Kiyoshi Ota/Getty Images News/Getty Images
