Edge-lit microlenses improve LED backlighting efficiency

Flat-panel displays can benefit from the energy efficiency of light-emitting diodes (LEDs) used as backlights.

Sep 1st, 2007
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Flat-panel displays can benefit from the energy efficiency of light-emitting diodes (LEDs) used as backlights. However, common diffusion screens and/or the need for multiple LEDs arranged in an array to uniformly distribute the light intensity can correspondingly increase the overall display thickness and power consumption. In response, engineers at Global Lighting Technologies (GLT; Brecksville, OH) are applying their MicroLens technology-a patented, pixel-based edge-lighting technique that uses molded microlens arrays-to efficiently channel the light from a single (or a very small number) of LEDs over a broad display area without adding additional thickness (for another approach, see “Wavy prism sheet makes LCDs look better,” p. 20).

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The MicroLens technology uses as many as 180,000 light-extraction features per square inch that can be controlled to within 5 µm, with customized shapes, depths, and thickness values as low as 0.4 mm, in configurations that can easily illuminate a 5 in. (diagonal) display using one edge-positioned white-light LED running at 20 mA or less. Compared to printed or etched-dot diffusers or V-groove arrays, MicroLens technology enables illumination uniformity of 80% using far fewer LEDs. The technology also allows for non-uniform or directional discrete-area backlighting for such applications as keyboard overlays to illuminate specific characters, logos, or buttons. Contact David DeAgazio at info@glthome.com.

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