Method and apparatus for detecting and removing foreign material from a stream of particulate matter
AssigneePhilip Morris Incorporated
InventorsPeter Martin, Avis N. Wyatt, Jr., Hector Alonso, Norman R. Rowe, Robert S. Southard, Stephen G. Zimmermann
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Abstract
A method and apparatus are provided for detecting and removing foreign material which may be found in a stream of particulate matter, such as tobacco. The tobacco is allowed to fall in a cascade past an optical detector. The turbulence of the falling motion brings a large proportion of the particles in the cascade into the field of view of the detector. When foreign material is detected, a signal is generated to activate a fluid blast directed at the portion of the cascade in which the foreign material is located.
Claims20
Apparatus for detecting foreign material in a stream of particulate matter, said apparatus comprising:
- first conveying means for delivering a stream of particulate matter containing foreign material to said apparatus;
- second conveying means located below and spaced vertically from said first conveying means for conveying said stream of particulate matter away from said apparatus, such that said stream of particulate matter is transferred from said first conveying means to said second conveying means by falling therebetween under the influence of gravity in a turbulent cascade;
- illuminating means for illuminating said turbulent cascade of particulate matter while it is falling between said first and second conveying means;
- detecting means for detecting light reflected from said illuminated turbulent cascade of particulate matter;
- and
- control means for comparing, without resort to a background reference, the light reflected from said illuminated turbulent cascade of particulate matter containing foreign material with the light expected to be reflected from a turbulent cascade of the particulate matter free of foreign material and for generating a signal when said reflected light indicates the presence of foreign material.
Apparatus for removing foreign material from a stream of particulate matter, said apparatus comprising:
- first conveying means for delivering a stream of particulate matter containing foreign material to said apparatus;
- second conveying means located below and spaced vertically from said first conveying means for conveying said stream of particulate matter away from said apparatus, such that said stream of particulate matter is transferred from said first conveying means to said second conveying means by falling therebetween under the influence of gravity in a turbulent cascade having first and second sides;
- first illuminating means for illuminating said turbulent cascade of particulate matter while it is falling between said first and second conveying means;
- first detecting means for detecting light reflected from said illuminated turbulent cascade of particulate matter;
- control means for comparing, without resort to a background reference, the light reflected from said illuminated turbulent cascade of particulate matter containing foreign material with the light expected to be reflected from a turbulent cascade of the particulate matter free of foreign material and for generating a signal when said reflected light indicates the presence of foreign material;
- first deflecting means responsive to said signal for directing a blast of fluid under pressure at a portion of said turbulent cascade of particulate matter when said control means determines that foreign material is present in said portion of said turbulent cascade of particulate matter, said blast of fluid deflecting said foreign material from said turbulent cascade.
A method for removing foreign material from a stream of particulate matter containing foreign material, said method comprising the steps of:
- causing said stream of particulate matter containing foreign material to fall under the influence of gravity in a turbulent cascade having first and second sides;
- illuminating a first side of said turbulent cascade of particulate matter at a first illuminating height;
- detecting the light reflected from said illuminated turbulent cascade of particulate matter at a first detecting height;
- comparing, without resort to a background reference, the light reflected from said illuminated turbulent cascade of particulate matter containing foreign material at said first detecting height with the light expected to be reflected from a turbulent cascade of the particulate matter free of foreign material, and generating a first signal when said reflected light indicates the presence of foreign material;
- and
- deflecting a first portion of said turbulent cascade at a first deflecting height in response to said first signal.
Dependencies are inferred from the claim text.