Edge-Position Transducer Employing Reflectance
Original Publication Date: 1985-Sep-01
Included in the Prior Art Database: 2005-Feb-19
The system described herein detects the position of an edge by light reflection from the object of interest, such as a piece or web of paper. The key feature is the use of feedback from a reference sensor which changes the illumination level to compensate for changes in the reflectance so the edge detector output remains proportional to the edge position with respect to the edge detector. Fig. 1 shows the mechanical arrangement of the system. Target 1 is the paper or other substance to be sensed. It is illuminated by light-emitting diode 2, which by means of a cylindrical lens 3, illuminates area 4. Illuminated area 4 is common to reference detector viewing area 5 and edge-detection viewing area 6.