US Patent 7350415 Closed-loop comb drive sensor

A closed-loop, comb drive device that reduces certain “common mode” sensor errors. The device includes a comb structure, electronics, a substrate, and a position sensor. The comb structure includes two comb-drive sections, each having at least two subsections. The comb drive sub-sections in each section are positioned in a diagonal relationship to each other relative to the device axes. A separate pick-off section, along with the electronics, determine which of the two drive sections should receive a voltage differential, and the size of that differential. The diagonal relationship within each drive section eliminates many of the large scale factor errors which often occur in prior-art designs.