Brelco offers a new high-brightness TFT line ideal for use in severe environmental conditions. Brightness values up to 1200 nits (depending on the size of the TFTs) are available, providing a very high visibility even in direct sunlight. As an option and as an improvement feature, these TFTs can be equipped with Optical Bonding technology (see below).
Optical Bonding: Optical Bonding: a solution that improves readability to sunlight, and provides greater resistance to vandalism in outdoor environments, flat display screens, and portable devices. Optical Bonding technology puts a cover lens, as well as an anti-reflective glass or touch panel, directly on the display glass and eliminates the intermediate air layer to reduce reflections to less than 0.2%, greatly increasing the contrast ratio in environments with strong light sources.
Basically, it consists of a layer of adhesive designed to be optically inert placed between the LCD glass and a protective glass. Lacking an air layer eliminates the risk of moisture between the two glasses and improves overall optical performance. It is also possible to apply anti-reflective and anti-reflective coatings that allow a drastic reduction of reflections making a TFT truly readable to sunlight.
It's important to underline the role of contrast in outdoor visualization. More than brightness, in fact, Contrast Ratio (CR) is the key to achieve a real good sunlight readability. In math terms CR is the difference between the light intensity of "white" pixels (all lighted on) and the dark ones (all lighted off); or white level against black level. In the ratio formula also the reflections are considered and summed to each light intensiity:
CR = (white area + reflections) / (black area + reflections)..
So become clear that introducing layers and covering such as Optical Bonding, Anti-Reflective and Anti-Glare filters able to strongly reduce refelctions, can greatly improve the CR and, as a consequence, the TFT's readability under full sunlight. Most recent literature about LCD technology consider a value of 7:1 the base to get a good visibility under direct sunlight or hard environmental conditions.