METHOD OF DETECTING AND INSOLATING PIECE OF INSULATING SUBSTANCE BETWEEN SMALL PIECES OF CONDUCTIVE SUBSTANCE

摘要

When small pieces of a conductive substance such as raw pulp materials or grain are supplied by a belt conveyor (2), the surface potential of any pieces of an insulating substance such as mixed plastics becomes higher than that of the small pieces of conductive substance due to friction. The surface potential is measured by an electrode (8), is amplified as a time-differentiated value by an amplifier of a surface potentiometer (7), the output is supplied to a comparator (10) to compare the output with a reference potential to detect whether or not the absolute value thereof is higher. Thus the presence or absence of mixed insulating substance pieces can be detected.