Lingraphica is a registered trademark of Tolfa Corporation. It, like its predecessor, translates keyboard key-presses or electronic representations of letters into movements of the fingers of the mechanical hand. With a fingerspelling hand, a deaf-blind individual need not rely on a human interpreter for all communication. More reliable, better control Significant improvements in the mechanical, computer, and software systems are embodied in this new device. Mechanically, each hand motion is driven by a servo motor as in Dexter.
Cables are wound around the motors' pulleys, routed up each finger, and attached to their tips.
The fingers themselves are constructed of Delrin segments attached to each other by a strip of carbon fiber, replacing the torsion springs used in Dexter. The carbon fiber provides the flexible hinge for finger flex and the restoring force necessary to extend the finger. The system's computer hardware consists of an 8 bit microcontroller module and associated digital circuitry. This compact assembly unit is mounted behind the servo motors under the hand. The computer software implements a new fingerspelling algorithm that results in smooth transitions from one letter to the next.