A piezoelectric active-mode incrementor switch system (100) includes two
ratchet wheels (118, 124) that are rotationally mounted on a drive shaft
(112) having a knob (102). The ratchet wheels (118, 128) form a slipping
clutch with their respective drive wheels (116, 128) which are rigidly
mounted to the drive shaft and mechanically loaded with spring (120). The
ratchet wheels (118, 124) are mounted inversely to each other on the drive
shaft (112) and make contact with their respective cantilever beams (114,
136) which each have a piezoelectric film. In operation, the switch (100)
functions by mechanically stimulating the piezoelectric beams. When the
knob (102) is rotated in one direction, only one of the beams (114, 136)
is displaced causing a generation of an electrical charge that acts as a
signal. The other beam (114 or 136) is prevented from moving and therefore
its beam does not produce a signal. When the knob (102) is rotated in the
opposite direction, the other beam that was previously prevented from
moving is displaced causing an electrical signal to be generated by the
switch.