LED Arrays
LED arrays, with their high brightness, are best suited for use in small LCD backlights. The LED array consists of a matrix of LED chips typically mounted to the LCD module’s pc board. For a standard 2x16 LCD as many as 36 LED chips are needed. While LED arrays work well in all lighting environments, they also have a high power appetite, can run hot, and are available typically only in yellow-green. Supply voltages to LED arrays are typically 5V DC although 12V can sometimes be used.
LED Edge lit
LED-based light guides are particularly effective for small- to mid-sized backlights, especially since the introduction of new, higher-efficiency white, blue and green LEDs offering significant brightness improvements. The brightness level of backlights based on these new LEDs can be eight to 10 times brighter than traditional yellow-green types. The light guides offer: long life; low voltage and power; high brightness and mechanical versatility. New methods of light extraction continue to be developed, such as pixel-based and moulded methods that improve the performance and reduce the cost of the backlights. Where space is a concern, light guides can incorporate side-firing LEDs reducing total backlight thicknesses to <1mm. Supply voltages to LED edge lit backlights are typically 5V DC.
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| LED Array |
LED Edge Lit |
| Pros | Cons |
White, Red, Green, Blue, Yellow or Amber available | Very high brightness not possible |
High Brightness up to 6,000cd/m2 |
> 1mm thickness |
Up to 100,000 hours | Hot spots |
Good uniformity > 80% | Up to 5W power for large size |
Only DC supply required | |
Ideal for small or medium size displays | |
Customisable | |
Down to 50mW power | |
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