LED BACKLIGHTING TECHNOLOGY

Today’s state-of-the-art LEDs have come a long way in terms of offering more brightness in a smaller package, and ongoing advances in LED technology are enabling LCD backlight manufacturers to better meet the ever-increasing challenges posed by small displays used in portable and handheld products. They’re available in a broad range of colors – white, green, blue, red, orange-red, amber and more. There are even LEDs that can achieve the full array of colors in just one package, making it possible to light your display in any hue from just one LED. And they’re getting ever smaller, too. Today, the thinnest production LEDs are around .6mm high, and packages are continually getting smaller.

LED DESIGN CONSIDERATIONS FOR BACKLIGHTING

The LED package you choose, the number and spacing of the LEDs, and the LED current determine what levels of uniformity, brightness and overall visual smoothness you get. GLT offers multiple LED packages to meet your mounting and space requirements, and we can recommend a light source configuration to meet your product specifications. Available packages include LEDs for surface mount cellular phone or PDA applications, and LEDs with square packages that are ideally suited for insert molding. The surface mount LED can be attached to a flex circuit or small LED by GLT to provide a complete backlight module solution. Insert molded LEDs will typically require hand soldering of the LED leads, but this improves efficiency because of the optical bond of the LED to the light guide. The square package LED is the typical package for mid-sized displays in both GLT's proprietary configurations as well as from the manufacturers of high brightness, high efficiency LEDs.

A key technique used to enhance uniformity is lens arrays. Lens arrays are light distribution features that are located on the edge of the light guide (in front of the LED), and they help to provide for a uniform visual appearance using a reduced number of light sources by increasing the angular output distribution of the LED, while minimizing the hot spots that can occur when an LED is too close to the viewing area. Using lens arrays permits a reduction in the number of LEDs required while still achieving a uniform backlight. This enables cost, space, component and power savings.

Lens array design capabilities for LED-based backlights offered by GLT include:

• State-of-the-Art Ray Tracing Software
• Proprietary Light Source Models
• Rapid Prototyping

Single LED Backlight Design Without Lens Arrays	Single LED Backlight Design With Lens Arrays (Iteration One)	Single LED Backlight Design With Lens Arrays (Iteration Two)	Single LED Backlight Design With Lens Arrays (Iteration Three)

CCFL BACKLIGHTING TECHNOLOGY

Global Lighting Technologies also offers the benefits of its MicroLens technology for larger format displays utilizing cold cathode fluorescent lamps (CCFLs). MicroLens™ CCFL light guides are ideal for notebook computers, desktop monitors, portable DVD players, scanners, and other high-volume consumer applications where higher output and lower cost are important. MicroLens™ technology for CCFL applications offers optical performance improvements over conventional backlighting construction methods that translates into the following benefits:

• Higher Efficiency
  • Equal brightness to other competitive backlighting solutions at reduced power requirements.
  • Superior output relative to other competitive backlighting solutions

GLT’s CCFL backlight assembly for 15-inch desktop TFT (thin film transistor) LCD monitors utilizes a backlighting panel through which light extraction features are precision-molded into the panel, maximizing lighting efficiency and minimizing cost. Up to 30,000 optical features per square inch can be individually customized to optimize the light ray angles, particularly when using light management films to enhance brightness.