Another ingredient in the pin screen design is a per-pin feedback network and means for measuring how far out of its sleeve any one pin might be at any given time.

I propose laser-etching the side of the pin with a binary code in pits like those on the surface of a laser-disk, and using laser/photodetectors surface-mounted onto the manifold itself to read the code. The feedback mechanism would be able to detect and measure touch or mechanical pressure by computing the difference in volume of the air pumped into the cylinder, compared to the actual position of the pin in the cylinder.

Copyright 1999 (c)