Displays can be characterized not only by size, but by their typical brightness. TVs have typically required brightness higher than 400 nits, because TV is generally in the living room and watched from a distance. In contrast, brightnesses of less than 300 nits are typically sufficient for IT devices (e.g. notebook PC, monitor, etc.), because these are usually viewed from shorter distances. For LCD TVs in particular, high brightness was even used as a marketing point against plasma TVs, whose full-white brightness is typically under 200 nits. However, the current trend in LCD TV is toward lower brightness.
While there have been low-brightness TV models in the past, most were in small sizes, targeting the secondary TV market. The first trial for low-brightness TV models in the main segment of large TVs started early this year with the introduction of low-cost direct LED backlight TVs. These sets trade off design and picture quality for cost, sacrificing thickness to reduce the cost of the light guide plate, and brightness to reduce LED cost. These designs have been able to reduce the cost gap between LED and CCFL backlights to less than 1.3X, enabling the set prices to be similar. These low-brightness LED-backlit TVs gained consumer acceptance, and accounted for more than 10% of total LCD TV shipments in Q2’12.
The success of low brightness models has led TV makers to plan more models with low brightness, even those using edge LED backlights. A brightness of 400 nits, which is the traditional level for LCD TVs, will soon be found only in high-end models. Most mainstream TV models are being designed with brightness of about 350 nits. Furthermore, some entry-level models are expected to have brightness as low as 250 nits, to fight against low-cost backlight TV models whose brightness is generally ranged 300-350nit.Lowering the brightness of an edge-lit backlight to 250 nits can reduce the cost premium over CCFL from 2X to 1.5X, which is still larger than that of low-cost direct LED backlights, although the edge backlights are much slimmer. Therefore, the real target of low-brightness edge LED backlights is the low-cost direct LED backlight, not CCFL. Now, low-brightness edge LED backlight TVs are targeting the new entry segment created by low-cost direct LED backlight TVs.