As the competition between OLED and LCD technologies heats up, news over the past week indicates that there will be consolidation in other display technologies. One of the technologies, MEMS, is being consolidated just as the first commercial product is coming to market. Another display technology, FED, does not have as bright of a future.
The idea of using Micro Electro-Mechanical Systems (MEMS) in a direct-view display originated at MIT in the 1990s. It became the basis for a company called Iridigm, which was acquired by Qualcomm in 2004. Since then, Qualcomm has been investing in the technology, including building a pilot fab and a high-volume fab in Taiwan that will begin full production in 2012. Last month, Qualcomm announced that Korean bookseller Kyobo will sell e-readers that include Qualcomm’s mirasol display technology.
Qualcomm’s mirasol technology utilizes MEMS to control structures that enable reflective cavities of varying depth inside a display. When external light reaches the display, the depth of each cavity determines the wavelength (and color) of light reflected. With each cavity representing a pixel, a reflective color display can be made.
Other companies have developed MEMS displays that use the structures as shutters to control the light from LEDs. One of these companies, UniPixel, has moved away from displays in favor of optical film. The other is Pixtronix, which also has roots in MIT. Pixtronix has developed its own prototype displays, and has been working with Hitachi, Samsung, and CMI to bring its technology to mass production.
Qualcomm has not stated officially that it has acquired Pixtronix, so we can only speculate about its plans. One possibility is that Qualcomm, which relies on licensing for much of its revenues, plans to license the Pixtronix IP. Another is that they could use some of the Pixtronix technology in their mirasol displays, potentially to integrate lighting. Yet another possibility is that Qualcomm could have plans to produce Pixtronix displays in their own fabs.
Whatever the outcome, it is clear from Qualcomm’s production investments, the commercial availability of its products, and its purchase of Pixtronix that it sees MEMS displays as a promising technology. It is interesting that the other successful example of MEMS in displays, microdisplays, was also controlled by one company, Texas Instruments.
The outlook for FED technology is not as positive, however. Field Emission Display (FED) is based on high-voltage vacuum technology that originated in the 1970s at SRI and later at the French research institute LETI. The technology can be described as a CRT in flat panel form, in that it fires electrons at a phosphor screen to produce colors. Instead of a single gun that is scanned across the phosphors, FEDs have micro-emitters in each pixel. FED developers have faced two key challenges: how to keep the emitters from destroying themselves, given the high voltages involved, and how to hold together a thin display under the conditions of a high vacuum.
In the 1990s, there were several different companies pursuing the technology, all of which exited the business, leaving Candescent Technologies, which partnered with Sony. After Candescent declared bankruptcy, Sony acquired the rights to the technology, which it sold to AUO in January 2010. AUO built a new team to develop the technology, but after nearly two years of work, and in the face of financial difficulties, AUO apparently decided to focus on other technologies, such as oxide TFT for LCD and OLED. This would seem to be the end of the road for FED, as there are no other display manufacturers seriously pursuing the technology, at least not the type that uses micro emitters.