Paint-on displays get closer to reality. (Technology).

A new way to make electronic displays--like the ones in digital watches, cell phones, and laptop computers--may lead to changeable screens that can be painted onto walls and fabric.

In current electronic-display technology, two thin glass plates typically sandwich a layer of liquid crystal, whose constituent molecules align in one direction until a change in an electric field causes them to pivot. Those changes of orientation alter the flow of light through the device, generating an image.

Dirk J. Broer of Philips Research Laboratories in Eindhoven, The Netherlands, and his colleagues have found a way to discard the top plate. First, they paint a film of liquid crystal onto a glass plate along with two other chemicals that form polymers when exposed to ultraviolet light. When struck by that light through a gridlike mask, one of the polymer-making chemicals solidifies into an array of pockets. Each of these, because it contains liquid crystal, can later serve as a pixel within an image. Exposure of the preparation to a different wavelength of UV radiation forces the second polymer-making chemical to harden into a thin, transparent overlayer. The researchers describe the method in the May 2 Nature.

"There are still hurdles to overcome," notes Peter Raynes of the University of Oxford in England in a commentary in the same issue. Still, he says, the new method could "open up the possibility of `painting' a display onto almost any substrate."--P.W.