Graf/Pen

Abstract

The Graf/Pen is a digitizing or data gathering device in which the operator simply holds a pen to point or to create graphical input for digital systems. Previous attempts to provide a natural graphical input have suffered from one or more disadvantages. The method in which strings extend from the cursor to mechanical or optical encoders (mangiospago) does not allow the operator to sketch as naturally as with a pen. The method of crossed wire grids and capacitive sensing known as the Rand Tablet is inherently expensive while being limited in size and format. Other methods using resistive sheets and capacitive sensing suffer from poor integral linearity, and in addition, require ADC's. Our own R & D group has long had all of the technology needed to solve the problems, but we were in a different area of science and were unaware of the need for a natural man-machine interface. A little accidental cross-fertilization between us and computer scientists prompted us to develop the extremely simple and versatile device I am about to describe.