Optimal design of a ferromagnetic yoke for reducing crosstalk in optical image stabilization actuators

In this study, we propose the optimal shape of a ferromagnetic yoke intended to reduce the crosstalk that occurs because of fringe effects at the edge of the magnet used in optical image stabilization (OIS) actuators. Topology optimization was performed with finite element (FE) analysis to determine the optimal shape of the ferromagnetic yoke without degrading the performance of the actuator. To promote the effective use of the topology optimization, the problem was simplified into a 2-D FE analysis, and finite difference approximation was used in the sensitivity analysis. The closest objective function to the special reference value was defined to minimize both the standard deviation and the average magnetic flux density in the y-direction for the Hall effect sensor. Consequently, the optimal shape of the ferromagnetic yoke, obtained by using topology optimization under various volume fraction constraints, was verified using 3-D FE analysis. The results demonstrate that the suggested design method is useful and effective.