Organic Looks Viable Again
by Paul McGoldrick
For a journalist in the world of electronics there are a few periods
in the year when in-boxes fill with anxious news releases that relate to
a particular trade show. In my case this happens just before and during
Electronica, NAB and -- at this time of year -- CES.
I haven't actually been to a CES for some years. The drive to make appointments at the various exhibits wilts as you start to get late just on the first day -- and you never catch up. Also, the materials on display, and that are being pushed, are usually vaporware, or close to it, and just don't fit into a component level approach that is unique to analogZONE.
Among the hundreds of e-mails during the last few days there is one product that really stands out from the rest: a 21-inch OLED display from Samsung. I, for one, did not expect this size of OLED for a few years yet.
The organic light emitting diode (OLED, also known as light-emitting polymer) was developed by Eastman-Kodak and uses a minute amount of an organic polymer (about 0.1 mm) that is charged by a voltage source. There are a number of layers on the substrate and light is emitted when charge carriers move towards one another (photophosphorescence). After the potential is removed the carriers recombine. Color displays can be created by either changing the energy level of the charge carrier combination involved or by using a white OLED with color filters (active or passive matrix) -- the latter is a little less efficient but seemed to be the way that larger displays might go.
Some of the advantages of OLED over an LCD, for example, are a wider viewing angle (up to 160°), lower voltage operation (1.8 V to 10 V, typically), longer life, lighter weight, no backlighting required -- therefore lower power -- faster response times, better operating temperature range and a thinner display. All good stuff and the technology seems ideal for smaller portable equipment displays, such as produced by Sanyo.
Another intriguing direction that OLED was, and presumably still is, going is to make the displays flexible (FOLED) so that you would, literally, be able to roll up your display and put it in your pocket. (Maybe the future for reading your morning newspaper?)
But Samsung has broken through (maybe two years before the nearest competition from Epson or Seiko -- who is looking at a 40-inch OLED) with the announcement of a 21-inch OLED with a resolution of 6.22 Mpixel (WUXGA) and that gives a brightness of 400 nit, a contrast ratio of 5000:1 and a color gamut of over 75%.
The real breakthrough, however, is that the process technology used is an amorphous silicon (a-Si) which can be produced on the extensive TFT-LCD lines that Samsung already has in operation. The cost benefits to the company are going to be huge.
Yesterday, my first choice in a flat-panel display for HDTV would have
been a DLP one using TI's brilliant technology. Today, I don't know, but
what I do want is to see a DLP monitor and a Samsung OLED monitor
side-by-side with the same native source material. Hell, if someone was
willing to set it up in Las Vegas I would even go to see it!