Position transducer

Abstract

A sealed position transducer which is self-wiping and which is readily adaptable for providing both linear and nonlinear electrical outputs. The transducer includes a housing, a resistive element received in the housing, and a flexible membrane, having a conductive portion formed thereon facing the resistive element, disposed over the resistive element and attached to the housing to seal the interior of the housing from the environment. An object whose position is to be sensed or measured is mounted on or connected to a carriage which movably engages a guide track formed as part of the housing. The carriage includes a roller which causes the conductive portion of the membrane to be deflected into contact with a portion of the resistive element. In one embodiment, where a linear relationship between resistance and distance is desired, a resistive element having a known, constant resistance per unit length is used. By measuring the resistance between the point of contact of the membrane and the resistive element, the distance of the roller from one end of the resistive element is readily determined. Where a nonlinear relationship is desired, a pressure contact clip is used to compress the conductive portion of the flexible membrane into contact with a selected portion of the resistive element.