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Optical fiber provides versatility

Posted: 16 Oct 2006 ?? ?Print Version ?Bookmark and Share

Keywords:versatile backlighting application? optical fiber application? versatile backlighting? fiber-optic technology? Brian Spahnie?

Spahnie: Fiber-optic technology has been gaining recognition as possibly the available and most versatile for certain display apps.

LEDs are being increasingly used in flat-panel display (FPD) backlighting and general illumination applications. While that's not news, it presents a quandary to engineers choosing the best LED backlighting technology for their design. All the designs claim to be the brightest, having the best image quality and uniformity, and lowest power consumption and cost to provide the most efficient use of today's LEDs. Not surprisingly, the answer depends on the application, the key criteria and the inherent versatility of the backlighting and illumination technology. Fiber-optic technology has been gaining recognition as possibly the most versatile available for certain display applications.

Not all large FPD applications require a full-color display with full-motion video, as LCD TVs and digital signage do. Operator interfaces such as test instrumentation and membrane switches generally use smaller, passive-matrix monochrome LCDs. Makers of test instrumentation, motor controllers and handheld data-collection devices are concerned with the brightness and uniformity of the displayit has to look good. But these are often low- to medium-volume applications where a stock module cannot be used. These also have key criteria of low power, no heat, no EMI, thinness, low tooling costs and a technology that's versatile enough to be customizable for the design. A backlight using patented, woven fiber-optic panels built from plastic optical fibers or rows of optical fibers mounted on a back reflector can provide a simple-to-design-in, easy-to-customize solution. This allows OEMs to integrate a high-quality backlight into their device without increasing cost.

Membrane switch
Increasingly, membrane-switch OEMs are using backlighting to enhance their user interface and increase the perceived value of the entire device to their customers. Of course, functionality remains critical, such as protection from heat and ESD, and the tactile feel of the switch itself. Fiber-optic panels built from rows of optical fibers can be placed between the overlay and the switch layer to provide even lighting over a wide area, with only a single LED and good tactile feel. Also, the designer may be looking to use an unusual (non-rectangular) geometry, including holes and other irregularities. This has traditionally been the domain of electroluminescent lamp (EL) backlighting. But optical fiber technology provides the desired brightness, uniformity, durability and low power consumption, without the EMI/RFI, degradation in brightness and inverter requirements associated with EL.

Fiber-optic technology's versatility extends to illumination applications beyond LCD and membrane-switch backlighting. In water environments like high-end spas and hot tubs, control panels can be backlit by encasing one of the new-generation of high-power LEDs. These LEDs deliver increased lumens per package into a fiber-optic "light engine," in which a special collimating lens captures and then focuses the light from the LED to the fiber-optic panel. Fiber-optic lines of light can be used in applications such as self-service DVD kiosks to provide brightly colored blinking enunciators that direct customers' attention to the retrieve and return slots, requiring no additional space, depth or retooling. Applications are continually being developed as the inherent versatility of fiber-optic illumination technology becomes better understood in the OEM marketplace.

- Brian Spahnie
Engineering Manager, Lumitex Inc.

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