Piezoelectric actuators, on the other hand, are very power efficient and provide a high output force, but a very small stroke necessitates aggressive leverage mechanisms to reach adequate displacements at the cost of lowering the force 20, 21, 22. They are also not power efficient due to the need for significant current flow in the coils, potentially even when the actuator is not moving. However, the need for high-turn coils and magnets makes such actuators difficult to miniaturize and batch fabricate by micromachining. These actuators, such as voice coil motors (VCM), can produce relatively large force and displacement and are widely used for autofocus (AF) and optical image stabilization (OIS) in compact camera modules in modern consumer electronics (smartphones, tablets, etc.) 17, 18, 19. Electromagnetic transduction, which is the main means of electromechanical energy conversion in macroscale systems, has been conventionally used in smaller scale systems. Transduction mechanisms commonly used in micromachined actuators include electrostatic, piezoelectric, electrothermal, and electromagnetic mechanisms. However, none of the existing micromachined electrostatic actuators can meet the large energy output requirements. Batch-fabricated micromachined (Microelectromechanical system) actuators can provide low-cost highly integrated solutions for these applications. For such applications, the actuator must provide displacements ranging from tens of micrometers to millimeters and supply forces in the mN range. Examples of such systems with subcentimeter dimensions include microrobots 1, 2, 3, 4, precision positioning systems 5, 6, 7, 8, optical systems 9, 10, 11 and medical devices 12, 13, 14, 15, 16. Wooters G, Silvertooth EW (1965) Optically compensated zoom lens.Electromechanical actuators that convert electrical energy into mechanical force or motion are an integral part of any electrically powered system with moving parts. Walther A (2001) Angle eikonals for a perfect zoom system. Tsai WB, Chang TY (1999) Analysis of flux leakage in a brushless permanent-magnet motor with embedded magnets. Qu RH, Lipo TA (2004) Analysis and modeling of air-gap and zigzag leakage fluxes in a surface-mounted permanent-magnet machine. Qian JB, Chen XD, Chen H, Zeng LZ, Li XQ (2013) Magnetic field analysis of lorentz motors using a novel segmented magnetic equivalent circuit method. Momen M, Datta S (2009) Analysis of flux leakage in a segmented core brushless permanent magnet motor. Milecki A, Ortmann J (2017) Electrohydraulic linear actuator with two stepping motors controlled by overshoot-free algorithm. Miks A, Novak J (2010) Analysis of two-element zoom systems based on variable power lenses. Lukac R, Martin K, Platanoitis KN (2004) Digital camera zooming based on unified CFA image processing steps. Liu CS, Tsai BJ, Chang YH (2017) A compact low-cost camera module with modified magnetic restoring force. Liu CS, Chang YH, Li HF (2016) Design of an open-loop controlled auto-focusing VCM actuator without spring plates. Lin YH, Liu YL, Su GD (2012) Optical zoom module based on two deformable mirrors for mobile device applications. Ko HP, Jeong H, Koc B (2009) Piezoelectric actuator for mobile auto focus camera applications. Hsieh CL, Chang YH, Chen YT, Liu CS (2018) Design of VCM actuator with L-shape coil for smartphone cameras. Hsieh CL, Wang HY, Chang YH, Liu CS (2017) Design of VCM actuator with the chamfered edge magnet for cellphone. Opt Express 22:11427–11435Ĭhiu CW, Chao PCP, Kao NYY, Young FK (2008) Optimal design and experimental verification of a magnetically actuated optical image stabilization system for cameras in mobile phones. Sens Mater 29(7):989–995Ĭhen MS, Chen PJ, Chen M, Lin YH (2014) An electrically tunable imaging system with separable focus and zoom functions using composite liquid crystal lenses. J Mech 30:467–476Ĭhang YH, Lu CJ, Liu CS, Liu DS, Chen SH, Liao TW, Peng WY, Lin CH (2017) Design of miniaturized optical image stabilization and autofocusing camera module for cellphones. Cao WZ, Yang XH, Tian XB (2014) Numerical evaluation of size effect in piezoelectric micro-beam with linear micromorphic electroelastic theory.
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