Page 256 - Introduction to Information Optics
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4.4. Optical Switching Based on MEMS 241
Side view
Stopper
Electrode
S
Top view
Fig. 4.31. A torsion mirror.
according to the applied voltage V. By comparing force with that in the parallel
capacitor, we found that the force in the comb-drive device is a constant
independent of the displacement x, and we can increasing the force by increase
the number of fingers in the comb, while maintaining a reasonable driving
voltage V.
Comb drives have become one of the most commonly used drivers in
making moving microelements, including moving micromirrors driven by the
comb drive through hinges and push-rods.
One drawback of comb drives is that fringing fields also give rise to forces
out of the plane, which can lead to levitation of the actuator away from the
