Fiber-optic backlighting fits under switches, buttons, indicators

By Control Engineering Staff August 3, 2006
Lumitex UniGlo fiber optics lights under circles, semi-circles, holes and other irregularities.

Strongsville, OH —Thin, flexible fiber-optic backlighting technology from Lumitex is now available in unusual geometries that were previously the domain of electroluminescent backlighting. Circles, semi-circles, holes, and other irregular shapes are possible using UniGlo patented fiber optics. Traditional membrane switches have been rectangular in shape, but some OEMs have been designing membrane switches with other, more unusual shapes to help differentiate their products in the marketplace.

UniGlo backlighting is said to provide brightness, uniformity, durability, and low power consumption. OEMs would like to create membrane switches with alternative shapes, such as ovals, rectangular with curved die cuts, or other custom shapes, which would improve switch identifiability.

The fiber-optic panels are positioned between the overlay and the circuit board/metal dome assembly, while a fiber-optic tail is routed around any obstacles to the LED, which is soldered into an appropriate space on the circuit board. Panels can backlight a large area with one LED light source (up to 4 x 6-in.) Because they are thin (0.013-in.), they don’t interfere with the tactile feel of the switch when the dome is depressed.

Brightness is as high as 75 Ft-L, and power consumption is low (2-4 V dc, 5-30 mA for a single-LED backlight). Fiber-optic panels have been tested to over 5 million actuations and provide backlight lifetimes up to 100,000 hours (depending on the LED light source used).

Cost ranges from $0.70 for a panel with a 0.40 x 4-in. viewing area and no LED in quantities of 100,000, to $4 for a panel with a 1.35 x 3.50-in. viewing area and one white LED in quantities of 5,000.

—Edited by Mark T. Hoske , Control Engineering editor in chief