Patent ID: 7326871
Filing Date: 2008-02-05
Classification: B07C

Abstract:
1. A system for sorting lignin containing articles from non-lignin containing articles, comprising a detector system which comprises a plurality of narrow bandwidth sources of electromagnetic energy of differing frequencies sequentially illuminating articles passing through the detector system, said plurality including a first source of narrow band energy illuminating articles traveling through the detector system with energy having a wavelength less than the wavelength of a red fluorescence from lignin in the articles and having a narrow enough bandwidth so as not to substantially overlap the red fluorescence from the lignin in the articles, the detector system further comprising a collector for collecting electromagnetic energy reflected and fluoresced from the articles and measuring the red fluorescence from the articles, a deflector for deflecting selected articles toward an alternative destination; and a control system, operably connected to the collector and the deflector, for actuating the deflector in response to the presence or absence of lignin in the articles, wherein a ratio of red fluorescence to reflected green light is calculated for each article in order to factor out intensity variation caused by some articles being closer to the collector than others.