Interlink Electronics Ring Sensor - Manual (Page 4)

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2
Ring Sensor
Integration Guide
3.0 Theory of Operation
The Interlink Ring Sensor is designed to overcome the shortcomings of a simple angular
potentiometer. A normal ring-shaped potentiometer would have a ring of resistor material broken
by a small gap. Electrodes on either side of the gap would be used to place a potential across the
ring. Touching a wiper against the ring would bring the wiper to a potential that is proportional to
angle. The problem with this arrangement is that when the wiper touches the gap, the potential is
undetermined. If the wiper is broad (as it is with a finger) the wiper could touch both electrodes at
once. In this case the potential on the wiper would be some kind of average of the two electrodes.
To solve this problem, the Interlink Ring Sensor has a continuous ring of resistor. Three electrodes
that are separated by 120° of arc drive this ring. The method is detailed on the next page.
Figure 1: Exploded view of the Ring Sensor.