Original Post by Bob Waddell, Jan 8, 2009

Overview

As more and more LCDs find their way into outdoor applications, the need becomes far greater for them to not only be able to withstand severe temperature extremes (heat and cold) and solar radiation, but the LCD must also be readable when exposed to extreme optical conditions such as direct and indirect sunlight, glare and reflection. On an average sunny day, the illumination of ambient daylight is approximately 30,000 nits. Therefore, a TFT’s brightness should be over 900 nits to get a clear image for an outdoor application.

Most off-the-shelf LCDs are not properly equipped to handle all of these requirements. There are  several brightness enhancement solutions to meet/exceed our customers’ requirements.

Benefits of Brightness Enhancements for TFT Modules

• Increase brightness up to 100% with enhancement films alone
• Improve display contrast and readability
• Improve display clarity and image quality
• Superior uniformity
• Improved operating temperature range and brightness

Options

Both passive and active backlight modifications can dramatically improve sunlight readability. One of the most efficient and cost-effective solutions is the GenFlective™ display, a hybrid of transflective and passive enhancements. Avnet also offers a standard transflective display, which incorporates a highly reflective polarizer that reflects ambient light back out of the display. Thirdly, Avnet provides the traditional value-add backlight solution, an active enhancement featuring your choice of CCFL, LED or NVIS backlight technology.

Passive Enhancements

Benefits of GenFlective™ Technology

• Requires no more power than OEM panel
• Dissipates no more heat than OEM panel
• Simplifies integration of value-add display
• Easier to address cooling due to low power
• Can often be combined with other passive enhancements (optical bonding) or active enhancements (sunlight/daylight readable backlights/edgelights)
• Typical enhancement of OEM luminance of 20% to 100%

A GenFlective™-enhanced LCD is a display that has been altered, using passive enhancements, to improve the brightness (transmissive and/or reflective) and/or the contrast of the display. Although each display has its own personality, due to differences in design, manufacturing techniques and in the stock film stack, our value-add partner can typically enhance the performance of an OEM panel utilizing Optical Management Films, Polarizers and Diffusers, and a multitude of films and coatings (Contrast Enhancement, Index Matched, Antireflective, etc.)The display would be characterized under darkroom conditions and three different simulated daylight conditions. We would then do an evaluation of the OEM films in the LCD and modify this configuration as we deem reasonable. We will do up to four iterations of backlight film modifications and submit the data to you, along with our analysis of what the data tells us. 

Transflective Panels

Although they are designed to reflect ambient light back out the display to augment its performance in direct sunlight, transflective panels have insufficient transmissive luminance (typically ~200 nits) to be considered usable in diffused lighting conditions where direct sunlight is not available (e.g., cloudy or rainy days).