Abstract

A contact sensor for detecting points on a grid where the sensor is being contacted on opposing sides by teeth surfaces or other contacting points. The contact sensor includes two sets of parallel electrodes which are each formed of a thin, flexible supporting sheet. The electrodes are coated with a thin, resistive coating. Two such electrode structures are oriented at approximately right angles to create a grid where the intersecting electrodes cross separated by the resistive coatings. The resistive coatings may be made from conventional resisitive inks and are optionally separated by a separation material, such as talcum or mesh. In the absence of an external force, the material between the electrodes sets provides a high resistance between intersecting electrodes. The novel composition of the intermediate layer results in a structure which provides a "switching" effect such that the resistance between electrodes is very high where there is no external pressure and changes to a comparatively low value at locations where external pressure is applied by two contacting points or surfaces. The sensor output is dynamic in the sense that the resistance will change back and forth between high and low resistance states as external pressure is repeatedly applied and removed. The sensor may be made extremely thin and can provide high resolution capable of distinguishing between contact points separated by 0.050 inches or less.Additionally, the sensor output may be provided by means of a small computer or similar digital processor which monitors the signals from the sensor grid and which provides an output which indicates the variation in contacting points with time.

Other References

• "A Force Transducer Employing Conductive Silicon Rubber", J. A. Purbrick, Apr. 1981, First Robot Vision and Sensors Conference
• "Active Touch Sensing", W. D. Hillis, Apr., 1981, Massachusetts Institute of Technology, A. I. Memo 629