| 摘要 |
A sorting system (10) propels a stream of randomly arranged PET and PVC articles (12, 14) through an inspection zone (20) including a first light polarizer/analyzer combination (24, 26), an article-detecting gap (G), and a second light polarizer/analyzer combination (28, 30). The first and second polarizer/analyzer combinations are oriented to extinguish normally incident light in the absence of articles in the inspection zone and are offset 45 degrees relative to each other such that at least one polarizer/analyzer combination detects a principal axis of birefringence of PET articles. The gap is employed to detect the presence of an article in the inspection zone. A video camera (22) includes first, second, and third CCD arrays (58, 60, 62) positioned to receive respective light rays (48, 64, 50) from the first light polarizer/analyzer combination, the gap, and the second light polarizer/analyzer combination and to generate first, second, and third video signals representative of the light each receives. A video signal processor (68) processes the second video signal to identify the presence of multiple articles in the inspection zone, processes the first and third video signals to determine whether each of the multiple articles is made from PET, and selectively activates air ejectors (70) to separate the PET articles from the other articles.
|
