Optical sorter

An optical sorter comprising three optical sorting units for sorting materials to be sorted according to good/bad quality, each of the optical sorting units including:

• optical detection means for detecting the materials to be sorted falling along a predetermined trajectory;
• ejection means for removing defectives from the materials to be sorted falling along the predetermined trajectory based on detection results obtained in the optical detection means;
• and
• discharge means that includes a non-defectives discharge unit arranged at a fall position of the materials to be sorted falling along the predetermined trajectory and a defectives discharge unit arranged at a fall position of the materials to be sorted displaced by the ejection means,
• wherein the materials sorted according to good/bad quality in a first optical sorting unit and discharged from a defectives discharge unit of the discharge means in the first optical sorting unit are transferred to a second optical sorting unit and sorted therein according to good/bad quality,
• materials to be sorted according to good/bad quality in the second optical sorting unit and discharged from a defectives discharge unit of the discharge means in the second optical sorting unit are transferred to a third optical sorting unit and sorted therein according to good/bad quality, and the optical sorter is characterized in that
• a fraction of the materials sorted according to good/bad quality in the first optical sorting unit and discharged from the defectives discharge unit is allowed to be transferred to the third optical sorting unit and sorted therein according to good/bad quality.