Multi-band spectral sorting system for light-weight articles

A method for sorting tobacco products, comprising:

• providing a conveyor belt having an infeed end, an opposite discharge end, and an upper supporting surface, and wherein the conveyor belt rotates at a selected speed;
• enclosing the upper supporting surface of the conveyor belt with a hood, the hood extending from the infeed end of conveyor belt to the opposite discharge end thereof, the hood defining a tunnel having a continuously diminishing cross sectional dimension when measured in a direction extending from the infeed end of the conveyor to the opposite discharge end thereof;
• providing a source of tobacco products to be sorted, and wherein the source of tobacco products is mixed with unacceptable items which are selected from a group which comprises cardboard, paper, rope, black butyl, and stained latex;
• depositing the source of tobacco which is mixed with unacceptable items on the infeed end of the conveyor belt;
• generating an air flow having a direction of movement within the tunnel, the direction of the air flow moving generally parallel relative to the upper supporting surface of the conveyor belt and from the infeed end to the opposite discharge end, and wherein the air flow has a first velocity at the infeed end of the conveyor, and a second velocity at the opposite discharge end of the conveyor, and wherein the diminishing cross sectional dimension of the tunnel increases the velocity of the air flow as the air flow moves from the infeed end of the conveyor to the opposite discharge end, and wherein the increasing air flow velocity stabilizes the source of tobacco mixed with unacceptable items on the upper supporting surface of the conveyor belt;
• providing an inspection zone which is disposed downstream of and in spaced relation relative to the discharge end of the conveyor belt;
• illuminating the source of tobacco which is mixed with unacceptable items as they move through the inspection zone with at least one illumination source which emits red, green, and infrared radiation;
• sensing the red, green, and infrared radiation reflected from the source of tobacco which is mixed with unacceptable items;
• generating red green and infrared radiation data from the red green and infrared radiation sensed in the inspection station;
• providing a data processor for receiving and processing the red, green, and infrared radiation data and generating sorting data based upon the red, green, and infrared radiation;
• and
• providing a sorter down stream of and in spaced relation relative to the discharge end of the conveyor, and wherein the sorter receives the sorting data from the data processor and separates the tobacco products from the unacceptable items.