Browsing by Author "Hsu, Jhih-Da"

Now showing 1 - 2 of 2

Design and implementation of a voice-coil motor servo control IC for auto-focus mobile camera applications
(2007)
Hsu, Jhih-Da
;
Tsai, Ching-Lung
;
Tzou, Ying-Yu
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents the design methodology to implement a fully digital control IC for the position control of the auto-focus (AF) lens module in applications to mobile phone camera using the field programmable gate array (FPGA). As compared with the conventional stepping motor control with a spring return fixture, the AF lens module is driven by a voice-coil motor (VCM) with a digital servo drive IC. The proposed digital servo drive IC includes a digital servo controller, a digital current controller, and a full-bridge dc-dc converter. The designed digital servo drive IC provides a total digital solution to the position control of the AF lens module in applications to high-performance light-weight slim-type mobile phone camera and video. The designed AF lens module can reach a control range of 0.6 mm within 30 ms with a control resolution less than 5 mu m, a peak driving force of 30 mN, and a peak output current of 120 mA.
Modeling and design of a voice-coil motor for auto-focusing digital cameras using an electromagnetic simulation software
(2007)
Hsu, Jhih-Da
;
Tzou, Ying-Yu
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents the modeling of a voice coil motor (VCM) used for the auto-focusing control of a digital camera in applications to high-performance mobile phones. The force constant and its associated back EMF constant of a VCM can be highly nonlinear with the mechanical structure. Conventional modeling technique using the derived flux distribution based on geometrical structure is quite involved and impractical to identify its equivalent parameters. A modeling procedure for a specially designed VCM is developed based on its mechanical structure and used material by using an electromagnetic simulation software - the Ansoft's Maxwell 2D. An iterative optimal design process is then proposed to maximize the force constant of the VCM with a specified volume. Simulation results with experimental verification are given to illustrate that the proposed design procedure can achieve a satisfactory performance.