Optimum Design of Magnetization Tool for Multi-Pole Magnet of Electrophotography

The electrophotography, such as a copier or a laser printer, requires a multi-pole magnet for its development system. Some of development magnets are produced by in-process magnetization of injection molded plastic magnet system. The process is nonlinear with respect to the relationship between a magnetization profile of the multi-pole magnet and magnetic flux density in the vicinity of the cavity and a lot of trial-and-error FEM simulation must be conducted to determine the configuration of magnetization magnets for the development magnet. To realize the efficient design system, the design problem of the magnetization tool is formulated as the optimum design problem. In this problem, the global optimum design is not always required. Because the specifications about their magnetic flux densities have upper and lower limitations and it is the most important that all magnetic flux densities at poles are settled between two limitations within reasonable calculation time. Therefore, random step method with membership functions which are determined by the temporary optimum design is proposed. It is possible to search the quasi-optimum design in reasonable calculation time by the proposed method.