LCD Backlight Unit: Cost Reduction
Backlight units (BLUs) is one of the most expensive components of a LCD. Similar in cost are color filters. A BLU account for about 30% of the material costs in a LCD TV panel. For a LCD monitor panel, the BLU is around 20%. There are opportunities to reduce cost if you look closely at the structure of the BLU. There are two different BLU types for a LCD TV. One uses two lower diffuser films and one dual brightness enhancement film (DBEF). The other uses one upper and one lower diffuser film and a brightness enhancement film (BEF). Within the BLU, DBEF and BEF is the most expensive components. But you cannot simply eliminate because as the names suggest DBEF and BEF plays a critical role in improving brightness. By using BEF instead DBEF you quickly save US$9 in material costs for the BLU. One of the main reasons for this is that 3M’s BEF patents have expired; 3M’s DBEF patents are still alive and therefore fairly expensive. Of course, if you completely rid of using either BEF and DBEF you will get even more cost savings but that would mean a 20% decrease in brightness from 500 cd/m2 to 400 cd/m2. This can be done by using three diffuser films in a 32″ LCD TV with 16 CCFLs. There are problems: with lower brightness the contrast ratio suffers because improvements in contrast ratio has mostly come from increase the brightness of whites due to the difficulty of making blacks darker.
As more competitors enter the market, prices will become more competitive. For many components of the LCD, the prices are very high due to oligopoloy-like markets that do not need to compete in an open market. For diffuser films, Japan’s Keiwa, Tsujiden and Kimoto are key suppliers. They have recently had to be more price competitive due to new suppliers such as South Korea’s SKC and Taiwan’s Exploit.
What this all means is that LCD TV prices will continue to come down in price and become more affordable to more and more. A sub-$999 40″ LCD TV would definitely accelerate the adoption of LCD TVs and so would a $499 32″ LCD TV.
Source: Witsview via Digitimes
DBEF has polarization recycling where BEF is a prism sheet so there is still a benefit to using DBEF. I would expect too much backlight gain can cause luminance uniformity issues when viewed too closely or from too wide an angle from normal.
I like your blog, by the way. Keep up the good work and interesting posts.
anchoku
January 20, 2007 at 12:04 am
Thank you for your comment. I appreciate the additional information regarding DBEF and BEF. What do you think is the most cost effective way to improve light efficiency from the backlight to the front of the screen besides the current trend toward removing DBEF due mainly to the price? Thanks again for your encouragement.
Max
January 22, 2007 at 12:23 pm