Machine Design

Fiber Optics brighten LCDs

Backlighting LCDs with cold-cathode fluorescent lamps (CCFLs) might be common, but it isn't necessarily the best method for membrane switches, digital controllers, test equipment, and medical devices.

Fiber optics brighten LCDs

A better alternative might be fiber-optic panels, according to Lumitex Inc., Strongsville, Ohio. Using a LED-driven fiber-optic panel to backlight LCDs offers several advantages, they point out. It uses less power and has a longer life, using only 10 to 100 mA at 2 Vdc, with a life as long as 100,000 hr. A single LED can illuminate a panel 4310 in., and unlike CCFLs, it needs no inverter.

The panels are constructed of up to eight layers that include one or more sheets of woven optic fibers, a polyester reflector on the back, and a semitransparent diffusion membrane between the topmost woven layer and a clear vinyl protective layer. They are assembled with double-sided adhesives, with each layer increasing brightness by up to 50 ft-L or more. Fibers from the woven layers extend from the panel as a bundled cable into a brass ferrule. This connects to a light source such as an LED, a low-current incandescent lamp, or a high-wattage halogen lamp.

Panels can be as thin as 0.013 in. They generate no heat or EMI, and they are unaffected by shock, vibration, and extremes in temperature and humidity.

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