Red Light, Green Light

Researchers at Philips and the University of Amsterdam in the Netherlands have created the first material for light-emitting diodes (LEDs) and flat-panel displays that can glow two different colors. Other electroluminescent materials, like the familiar LED indicators on VCRs, emit light of one fixed hue when electricity flows through them. As a result, multicolor devices, such as flat-screen televisions and computer monitors, have required three different materials-one each for red, green, and blue.

The new material is a mixture of a semiconducting polymer and a compound containing the metal ruthenium. Applying a voltage in one direction excites the metal, causing it to emit red light; an opposite voltage excites the polymer, which glows green. The dual-color material will allow designers to create full-color displays using two, rather than three, materials. This advance will simplify manufacture, and it will yield brighter displays because a larger portion of the screen surface will emit light at any given time. Philips expects the first small full-color displays that use the materials to be ready for market within three to five years.

Computercycle

Villagers in remote parts of India will soon be surfing the Web, thanks to a new Internet-on-wheels device. Built by researchers at the Indian Institute of Technology in Kanpur, India, in collaboration with MIT's Media Lab Asia, Infothela consists of a covered tricycle with a steel platform that carries a computer linked to the Internet by a wireless antenna. A 12-volt battery tucked below the platform powers the computer: as the Infothela operator rides from village to village, offering Internet access at each stop, a pedal generator recharges the battery. Should the rider tire, the battery can be charged with electricity from an outlet or a diesel generator. The Indian researchers are working on ways to translate Internet content into local languages, and they are developing audio- and video-based software that would make the Net accessible to people who can't read. Prashant Kumar, head of the project's mechanical-design team, expects Infothela to begin its village-hopping voyage within the next three to five months.

Color Coder

Remember those red-and-green glasses that made some movies look 3-D? Now there's an easy way to create similar effects on any printed matter-without glasses. A new color-rendering process from Xerox Research and Technology in Webster, NY, prints two images on a single piece of paper in such a way that each image shows up only under specific lighting-red versus blue light, say. The heart of the system is new software that allows precise control over the process. The user tells the program which wavelengths of light should reveal each image, and it translates that into instructions for a standard printer. The technology could make document authentication that uses hidden watermarks cheap and simple, as well as allow for popcorn boxes that display different images depending on the light from a movie screen. Xerox has filed for patents on the technology.