Roll up the iPad: Siemens advances the flexible screen

Vendors are rounding the final bend in the race to deliver foldable display screens and light sources that could transform not only gadgets, but also architecture, design, construction and fashion.
Written by Mark Halper, Contributor
Osram's OLED ribbon illuminating a square of colors. Photo from Siemens.

Siemens has taken us a step closer to a tablet PC that folds into our pocket, or a TV that rolls up in the living room when not in use.

The German industrial and engineering giant announced that its Osram lighting division has built a flexible light-emitting ribbon that has a record lighting efficiency for such things, known as organic light emitting diodes (OLEDs).

An OLED is a swath of  material that lights up in response to an electric current. OLEDs allow very thin screens because they do not require an extra layer of backlighting. They are available today in rigid form - glass. But flexible OLEDs made from plastic augur a whole new world of computers, gadgets and TVs that we can bend, roll up or fold away.

They also portend radical new possibilities in architecture, design and fashion, as OLEDs could bend into the fabric of furniture, wallpaper, buildings and clothing.

But one obstacle is that so far, flexible OLEDs do not operate efficiently enough to merit commercialization. In their current stage of development, they're not like their established counterparts, LEDs, which save energy because they require only about 20 percent of the electricity of a conventional incandescent bulb. (Light emitting diodes are a pointed light source, not a swath of material. LEDs are appearing in lightbulbs and other places; for instance, they can provide the backlighting for LCD displays).

Siemens claims to have now taken a big step towards rectifying that shortcoming. Its researchers at Osram have produced an 11-cm x 3-cm (4.3-inch x 1.2-inch) plastic ribbon that yields 32 lumens of light per watt of electricity. Siemens says this is more efficient than a halogen lamp, which delivers 10-to-20 lumens per watt, and than a conventional incandescent, which it says operates at 5-to-15 lm/w. Energy saving "CFL" (compact fluorescent bulbs) deliver 30-to-70 lm/w, according to Siemens.

As always in breakthroughs like this, lab advances are one thing, and commercialization is another.  The world will need screens wider than 1.2 inches on its phones, tablets and TVs. Osram will have to scale up its accomplishment into cost-effective, mass-produced, wider material.

It should also continue to improve efficiency. The University of Southern California has reported that, in principle, OLEDs could hit 100 percent efficiency.

Siemens has competition in this endeavor. Last fall, researchers at the University of Toronto claimed to have developed the most efficient flexible OLED. Using a different measure than Siemens they noted that the green spectrum could achieve "a maximum external quantum efficiency of 63 percent."

We hope to speak in detail with Osram's OLED chief soon to clarify the difference between his results and Toronto's. We'll also ask him to compare Osram with Samsung, which hopes to start shipping flexible screen gadgets this year.

One way or another, it's starting to look like the race to deliver foldable screens could soon round the final bend.

Note: Corrected incandescent efficiency to read "5-to-15 lm/w" on Feb. 13 at 12:25 p.m. PST.

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This post was originally published on Smartplanet.com

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