McAulay Fisher Nissen & Goldberg
Method for detecting colored foreign particles in light-colored powder and system therefor
 An efficient and reliable method and a system are proposed for detecting colored foreign particles in a white or light-colored powdery product such as a polyvinyl chloride resin with an object of product inspection and quality control. The method comprises the steps of eliminating static electricity from the powder, e.g., by spraying ethyl alcohol, continuously feeding the powder at a controlled rate on to a belt conveyor to form a uniform powder layer having a flat and even surface thereon, bringing the powder layer below a reflection-type laser-beam scanning detector projecting a laser beam with scanning and receiving the reflected beam and monitoring the output signals coming out of the detector. 
Shin-Etsu Chemical Co., Ltd.
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Hideo Masaru Hajime
Yoshikoshi Takeuchi Kitamura