Summary
(1) HannStar announcement of 'Field Sequential Color' (FSC) technology' for LCDs in smart phone and netbook is going to be another milestone in LCD technology that will finally migrate to LCD TV
(2) Field Sequential Color technology has failed in the past in LCD TV for 'color break-up' on the LCD screen. HannStar is not immediately applying this to LCD TV.
(3) HannStar is correct in introducing FSC in small area LCD like that in smart phone.
Analysis
Two years ago Samsung introduced 32" LCD TV with color sequential operation but the pictures exhibited 'color break-up' that was not acceptable to the market. Samsung did not continue on that. R&D work is still going on the field sequential operation of LCD. In this mode of operation, color filters are not needed. It is well known that color filters absorb nearly 60-70% of light in a traditional LCD. If the field sequential operation succeeds, LCD will become 70% more efficient and the power consumption will be reduced. HannStar has taken the right step of employing FSC in smart phone and netbook instead of jumping to LCD TV. It has to be seen whether 'color break-up' in moving pictures in this small area application is going to be felt by the consumers. Consumers do not use smart phones and netbook frequently for videos.
In the field sequential operation of LCD, the backlight is flashed with fully red color (appearing as red sheet of light) and the red pixels are addressed on LCD screen. After this, the backlight is switched quickly to blue color and the blue pixels are addressed on LCD. A similar operation is done with green color. The three colors are flashed with quick succession that is normally not noticeable by human eye. The LCD needs to respond faster in this mode of operation than in a traditional LCD. To accomplish this a special type of LCD known as 'optically compensated bend mode' (OCB) LCD is employed. Even at the rate of 180 Hz/sec human eye is able to notice the 'color break-up' in this mode of operation. This mode of operation involves LED backlight that employs red, blue and green color LEDs. White LEDs can not be employed for this purpose. The field sequential operation can be done in 'scrolling mode' as well.
Increasing frame rate and inserting 'black frames' are the ways to cheat the eye to eliminate 'color break-up'. Two years ago 240 HZ technology was not in a matured state. It is possible that HannStar solved the problem recently.
If this technology enters the market, the market for RGB LEDs will increase and the color filter market will come down. Again all LED manufacturing companies like Osram Optosemiconductors, Philips, Nichia, Cree, Toyoda Gosei, Seoul Semiconductors, Epistar, Farmosa Epitaxy will be benefited.
Munisamy Anandan consults with leading institutions through GLG
Analyses are solely the work of the authors and have not been edited or endorsed by GLG.
