GYRICON TECHNOLOGY

Electronic paper was first developed in the 1970’s by Nick Sheridon at Xerox’s Palo Alto Research Center. The first electronic paper, called Gyricon, consisted of polyethylene spheres between 20 and 100 micrometres across. The basic Gyricon display technology consists of a sheet of silicone elastomer in which many round spheres are embedded. The spheres are smaller than the eye can see and are made so that one hemisphere is one color and the other is a contrasting color. In addition to a different color, each hemisphere also has a different electronic charge. Every ball floats in its own small cavity, which is filled with silicone fluid. An electric field across the sheet can cause the ball to rotate. When the field is turned off, the ball settles against the cavity wall. Electrostatic forces maintain that state of rotation until an opposite electric field is applied, thus achieving bistable operation. Patterned electrodes allow us to rotate balls in selected areas, thus creating an image on the display. This is achieved by laminating the sheet between an electronic backplane and a transparent top electrode.

For situations in which the user needs central control of signs spread around a building or campus, these displays can be updated via a wireless router. One piece of software can control hundreds or thousands of signs if the designer assigns each sign its own network address and stores each sign's layout in the software scheduler. This program looks like commonly available scheduling software: any message can be scheduled for any time slot. Once programmed into the scheduler, the appropriate message appears on the sign at the appropriate time, whether it is a one-time message or a recurring message programmed far in advance.