Small multicolor LEDs with high brightness performance are ideal candidates for outdoor video displays with high resolution. This article will discuss the benefits of surface-mount LEDs which are made from a completely black package for highest contrast indoor video, as well as ingress protected (IP) LEDs for outdoor use. Surface-mount LEDs
LED video walls are everywhere today – from your favorite shopping mall, to airport exteriors to your favorite football club's sporting arena. For outdoor applications, LEDs are still the best light source to build screens bigger than 2m across diagonally. Besides pure screen size, the high brightness performance and outdoor capabilities of LED products are superior compared to LCD technology.
Figure 1: Outdoor video walls are becoming increasingly more common
Multicolor PLCC-6 packages are becoming more popular in the industry because they combine an easy driving configuration, uniform radiation characteristics and long lifetime performance in one package. Looking at Avago Technologies' new 3-in-1 RGB PLCC-6 “OneLED” (ASMT-YTx2 series) as an example, each chip can be addressed individually as it has its own anode and cathode pin for easy mounting and driving. Additionally, silicone encapsulation material and UV inhibitors in the LED packages give these PLCC-6 products the long life and durability required for outdoor applications. With an extended operating temperature range of -40°C to +110°C, these products can be used in a wide range of applications, even ambient lighting in saunas. For outdoor video wall applications, the extended operating temperature range makes it possible to install outdoor video screens even in locations with high ambient temperatures.
For high-resolution full video displays, small pixel distances and small form factor LEDs are required. A smaller LED package helps to increase the resolution while maintaining a high contrast ratio. For example, the Avago OneLED series has small package outlines of 3.4 x 2.8 x 1.8mm. As shown in Figure 2
, this helps reduce the pixel pitch down to 8mm, resulting in high resolution displays that can already be viewed from a relatively small distance to the screen.
Figure 2a/b: The small package of Avago OneLED devices reduce pixel pitch to 8mm