The comparison of Microlens Molded Light Guide technology vs. Direct LED backlighting shows how the use of a molded LED light guide between the PC board and keypad can tightly focus the light as it enters the thru-holes to the keypad, reducing the number of LEDs required.  
      

The diversion features molded into the Microlens molded light guide (above) eliminate diffusion and scatter of the light produced by the LED as compared to the direct LED backlighting method (at left), resulting in better uniformity. 
    
Microlens molded LED lightguides from Global Lighting Technologies (www.glthome.com) provide a high level of efficiency, performance and economy for backlighting keypads used in smart phones, PDAs, wireless handhelds and other applications.  When backlighting keypads, designers are continually looking to increase brightness and uniformity, reduce thickness, eliminate electronic noise, minimize secondary components, reduce cost, and reduce power consumption. 
  
Microlens molded LED lightguides address these key issues :
 - Brightness
 - Uniformity
 - Thinness
 - Design Flexibility
 - Efficiency
 - Power Consumption
 - Connectivity and Ease of Assembly
   
Microlens vs. Direct LED Backlighting :
Direct LED backlighting employs top-firing surface mounted, non-focused (120º viewing angle) LEDs placed between the keys. The brightness can be good but, since there is little or no way for this technique to channel the light uniformly, you need a lot of LEDs, combined with the diffusive properties of the keypad itself, to achieve acceptable uniformity. Due to the number of LEDs needed, cost, power consumption and PCB real estate become key issues.