An optical sorter is commonly employed as an equipment of sorting and processing for various kinds of particles. Recently, the optical sorter is demanded in various fields in order to improve the food safety and/or product quality of particles. It is, hence, desired to develop an optical sorter with high performance targeting widely various materials. An efficient sorting mechanism of the optical sorter has to be designed in order to improve the yield in the sorting and processing line and to increase the productivity.
  In the previous paper, we have reported about a study on air flow from an ejector nozzle of optical sorter using a numerical simulation approach. We clarified that the behavior of the air flow from the ejector nozzle strongly depends on the configuration of the ejector nozzle. In this paper, due to the productivity development of the optical sorter, we propose a product design approach from the viewpoints of social trends, customer needs, and customer benefits, instead of the conventional approach of engineering design from the viewpoints of only the scientific based result using CAD and CAE. Therefore, we also propose a method of applying the game theory to the multi-purposed trade-off design problem taking into account the economic viewpoint in the productivity development. The game theory can evaluate individual and collective rationality and select an appropriate solution from Pareto-optima of the multi-purposed design problem.
  In this paper, for the purpose of productivity and economic-efficiency improvement of the optical sorter, the ejector of the optical sorter is optimally designed. It is required that the air pressure is so high using less amount of the air that foreign particles are removed without mistakingly discharging a good particle. Although these requirements are trade-off each other, the air-pressure portion and nozzle height of the ejector is rationally decided using the game theory.

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