Abstract
This work focuses on a small electromagnetic actuator, which can be used to generate controllable motion. This actuator can be used as an objective lens actuator in an optical pickup head. The optical pickup head is a key component in an optical disc storage system, and the objective lens actuator is a key component in an optical pickup head in the meanwhile. In this work, an innovative actuator, which is referred to as a “flat type electromagnetic actuator”, is designed. The moving part of this actuator is a piece of printed circuit board, and the coil is made of copper foil. After the structure design is finished, the magnetic circuit is optimized by applying Taguchi method in order to improve the sensitivity of this actuator. In the beginning of this dissertation, general concept of an optical pickup head is introduced, including optical path design, basic servo, and some types of objective lens actuators. In the second part, the principle, simulation, structure design, and element design of the flat type electromagnetic actuator are introduced. In optimizing the magnetic circuit, the effects of the control factors on the magnetic flux density in the air gaps are identified as well as the optimal levels of the control factors. In the experiment part, the optimized actuator is fabricated. The frequency response of this actuator in the focusing, tracking, and radial tilt directions are tested, and the performance is close to what is predicted. The flat type electromagnetic actuator is assembled into an optical pickup head with the other optical and electronic components to test its performance. The test result proves the feasibility of this innovative actuator.