Systems for optically inspecting cylindrical surfaces

摘要

The entire cylindrical surface of a cylindrical object such as a cigarette is optically inspected by first inspecting at least 180 DEG of the circumference of a first side of the surface, and then inspecting at least 180 DEG of the circumference of the other side. Each of the inspection stations illuminates more than 180 DEG of the circumference and images the surface from two angularly spaced directions to ensure that at least 180 DEG of the circumference is seen at each station. Any object having a defective image is automatically rejected from the apparatus, and the images and other statistical information regarding the performance of the system are displayed by the system. The images are formed in such a way as to greatly increase the speed at which the inspection system operates so that it can keep up with the very high rates at which objects such as cigarettes are made in modern machinery (e.g., approximately 10,000 cigarettes per minute). The images are analyzed using techniques which make possible the detection of very small defects and also compensate for possible nonuniform illumination of the objects in the circumferential direction.