Browsing by Author "Tsai, Ching-Lung"

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A design of mini actuator for compact camera without using permanent magnet
(2014-01-01)
Tsai, Ching-Lung
;
Liaw, Der-Cherng
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電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents a design of mini actuator without using permanent magnet for auto-focus (AF) compact camera module (CCM) built on mobile phone, tablet PC and notebook. The current through the coils of electromagnets will yield magnetic force to move the moving part up and down. Comparing with conventional spring-type voice coil motor (VCM) and non-spring type VCM, the proposed actuator eliminates the concerns of rare earth supply and magnetic flux leakage which can fail the function of magnetic flux sensitive device such as e-compass. The proposed actuator also simplifies the power converter design from bipolar scheme as required by conventional non-spring type VCM to unipolar. A comprehensive electromagnetic analysis is performed by using finite element method to characterize the performance of the proposed actuator. Numerical simulations demonstrate that the magnetic flux leakage in the proposed actuator is much smaller than those by conventional design.
Design and implementation of a voice-coil motor servo control IC for auto-focus mobile camera applications
(2007)
Hsu, Jhih-Da
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Tsai, Ching-Lung
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Tzou, Ying-Yu
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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.
Friction Compensation of a Mini Voice Coil Motor by Sliding Mode Control
(2009)
Tsai, Ching-Lung
;
Lee, Ti-Chung
;
Lin, Shir-Kuan
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電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents a sliding mode controller to compensate the friction of mini voice-coil motor (VCM), embedded with guide pins, for position control in compact camera module (CCM) application. In the VCM, actuator full stroke is only 0.35mm or less, nonlinear friction force falls into mismatched condition and um-level resolution is required. With proposed controller, arbitrarily small steady state error can be approached by pole placement tithe sliding mode state equation. The performance is firstly simulated with a physical VCM model. The experimental result is then presented to demonstrate the proposed controller is able to avoid stick-slip oscillation that usually yields when using classic controller, such as PI controller.