A Design of Mini Actuator for Compact Camera without Using Permanent Magnet

Abstract:

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.

• Periodical: Applied Mechanics and Materials (Volume 607)
• Pages: 483-489
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.607.483
• Online since: July 2014
• Authors: Ching Lung Tsai, Der Cherng Liaw*
• Keywords: Auto-Focus, Magnetic Force, Mini Actuator, No Permanent Magnet

References

[1] H. P. Ko, H. Jeong and B. Koc, Piezoelectric actuator for mobile auto focus camera Applications, J. Electroceram. 23 ( 2009) 530-535.

DOI: 10.1007/s10832-008-9529-8

[2] S. Kuiper and B. H. W. Hendriks, Variable-focus liquid lens for miniature cameras, Appl. Phys. Lett. 85 7 ( 2004) 1128-1130.

DOI: 10.1063/1.1779954

[3] M. Shiraki and N. Sekiguchi, U.S. patent US7649703B2. (2010).

[4] C. S. Liu and P. D. Lin, Po-H. Lin, S. S. Ke, Y. H. Chang, and Ji-B. Horng, Design and characterization of miniature auto-focusing voice coil motor actuator for cell phone camera applications, IEEE Trans. Magn. 45 1 (2009) 155-159.

DOI: 10.1109/tmag.2008.2006564

[5] K. Nakamura, Y. Suzuki, H. Goto, and O. Ichinokura, Design of outer-rotor-type multipolar switched reluctance motor for electric vehicle, J. Appl. Phys. 99 (2006) 08R324.

DOI: 10.1063/1.2172180

[6] Y. H. Kim, J. H. Choi, S. I. Jung, Y. D. Chun, J. Lee, M. S. Chu, K. J. Hong, and D. H. Choi, Optimal design of switched reluctance motor using two-dimensional finite element method, J. Appl. Phys. 91 10 (2002) 6967-6969.

DOI: 10.1063/1.1452667

[7] H. D. Chai, Electromechanical Motion Device Prentice-Hall, (1998).

[8] L. K. Lai, C. L. Tsai, T. S. Liu, Design of Compact Linear Electromagnetic Actuator for Auto-focusing in Phone Camera, IEEE Trans. Magn. 47 12 (2011) 4740-4744.

DOI: 10.1109/tmag.2011.2160273

[9] M. J. Chung, S. Y. Son, Development of compact auto focus actuator for camera phone by applying new electromagnetic configuration, J. Mech. Sci. Technol. (KSME Int. J. ) 20 12 (2006) 2087-(2093).

DOI: 10.1007/bf02916325

[10] K. H. Kim, S. Y. Lee, S. Kim, A mobile auto-focus actuator based on a rotary VCM with the zero holding current, Optics Express, 17 7 (2009) 5891-5896.

DOI: 10.1364/oe.17.005891

[11] J. S. Choi, J. Yoo, N. C. Park, Small form factor actuator design for camera phone lens systems, Microsyst. Technol. 15 (2009) 1489-1497.

DOI: 10.1007/s00542-009-0795-4

[12] J. D. Hsu, Y. Y. Tzou, Modeling and Design of a Voice-Coil Motor for Auto-Focusing Digital Cameras Using an Electromagnetic Simulation Software, Proc. IEEE Annual Power Electronics Specialists Conf., PESC, (2007) 939-944.

DOI: 10.1109/pesc.2007.4342114