Abstract
We describe the detection method of shady objects which are unexpectedly mixed in kneaded food material while various kind of processings are given. It is difficult to detect nonmetallic mixtures like plastic, vinyl, seed, chip for their inconspicuous features, in general. Information of color, dielectric constant, reflection factor might be good characters for identifying them from the material. However, it is recommended to use appropriate information without any affect of these attributes of the mixtures as an ideal detection. Therefore we focused on the light transmittivity because the material has a tendency to diffuse light and produce shadows depending on the mixtures even when the object is nonmetallic. We devised a milky white hood having the cross angle π/3[rad] for illuminating the object so that the shadow becomes clear not at the material tip but at the place where the mixture exists. We show how the transmitted optical signals are processed. Experimental results are shown to prove the validity of the detection method.
