Optoelectronic device for automatically inspecting a group of cigarettes

Abstract

An automatic optoelectronic inspection device is located at a position downstream from a cigarette making machine and upstream from cigarette packaging machinery, and cigarettes are conveyed in groups to the inspection device where each group is inspected. The inspection device includes a plurality of photodetectors arranged so that there is a one-to-one correspondence between the position of a photodetector and the position occupied by each cigarette in a normally formed group. Each photodetector includes a light-emitting source for illuminating the end portion of a cigarette and a photoelectric transducer for sensing light reflected from the end portion of a cigarette in registration with the photodetector. The power to the light-emitting sources is controlled in such a way that the intensity of the light emanating from each light-emitting source is modulated at a high frequency. The signal produced by each photoelectric transducer is AC-coupled to circuitry for comparing each photoelectric transducer signal with a preset threshold signal, thereby substantially eliminating the effects of varying ambient light on the accuracy with which missing and improperly filled cigarettes are detected. If the intensity of reflected light is such that the photoelectric transducer signal is less than the threshold signal, the comparison circuitry indicates that a cigarette is missing from the group or is improperly filled, and the group of cigarettes is rejected. Other features are also disclosed.