Abstract: A compact electro-magnetic oscillatory actuator was proposed based
on a pair of torsion springs for optical scanners operating at low oscillating
frequencies, such as 50 Hz for a portable barcode scanner. Each torsion spring
in the actuator is made of silicone rubber and is dually supported at both
ends. A yoke is coupled with the driven coil to enhance the driving torque of
the actuator. In this study, we analyzed the effect of the yoke on the resonant
frequency of the actuator, as well as the torsion moment. We also
experimentally determined the relationship between the resonant frequency and
the magnetic gap of the yoke. Compared with the mechanical resonant frequency
in the experiments, which was designed to be 50 Hz, the frequency was modified
to 57.4 Hz, 54.7 Hz and 52.9 Hz when the gap between the yoke and the permanent
magnet was 1.5 mm, 1.7 mm and 1.9 mm, respectively. The proposed actuator,
which combines a yoke with flexible torsion springs, is potentially useful as a
compact optical scanner, taking advantages of both low power consumption and
high reliability.
Keywords: Optical scanner, oscillatory actuator, torsion spring, silicone rubber, magnetic spring
