Abstract
In this paper, auto focus actuator, which is used to move a lens module in the mobile phone having a camera module, is developed. Camera module containing auto focus actuator requires to minimize total size because of characteristics of the application area such as mobile phone, digital camera, and personal digital assistant. There are stepping motor, voice coil motor, and piezoelectric motor as auto focus actuator. In this paper, voice coil motor having new electromagnetic configuration is proposed. And actuator using proposed voice coil motor is developed by optimal design method using magnetic circuit analysis. The sectional area of the developed actuator is reduced to 32.4% compared with actuator using general electromagnetic configuration. From the performance test, the developed actuator has moving stroke of 0.64 mm for 2.1 volt, hysteresis of 40 μm, full stroke current of 54 mA, and unit step motion of 3 μm.
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Abbreviations
- barm :
-
Arm width of the plate spring
- Bg :
-
Magnetic flux density at the air gap
- Br :
-
Remanence flux density of the magnet
- dcoil :
-
Diameter of the coil
- E:
-
Young’s modulus of the plate spring
- Femag :
-
Electromagnetic force
- Fmin :
-
Minimum electromagnetic force
- g:
-
Air gap
- hcoil :
-
Coil winding thickness
- hmag :
-
Thickness of the magnet
- i:
-
Current flow
- imax :
-
Maximum current
- k:
-
Spring constant of the plate spring
- kml :
-
Magnet leakage factor
- Larm :
-
Arm length of the plate spring
- le :
-
Effective length of the coil facing with magnet
- n:
-
Coil winding number
- R:
-
Resistance of the coil
- rb :
-
Inner diameter of the barrel
- t:
-
Thickness of the plate spring
- tb :
-
Thickness of the barrel
- Tc :
-
Temperature of the coil
- tyoke :
-
Thickness of the yoke
- V:
-
Applied voltage
- Wcoil :
-
Coil winding width
- αm :
-
Magnet fraction
- δ:
-
Moving stroke
- μr :
-
Recoil permeability of the magnet
- ρ:
-
Resistivity of the coil
References
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Myung-Jin, C., Sung-Yong, S. Development of compact auto focus actuator for camera phone by applying new electromagnetic configuration. J Mech Sci Technol 20, 2087–2093 (2006). https://doi.org/10.1007/BF02916325
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DOI: https://doi.org/10.1007/BF02916325