Driving distributed mode loudspeaker actuator that includes patterned electrodes

A system comprising:

• a piezoelectric cantilever-type transducer of a distributed mode loudspeaker adapted to cause vibration of a load within a range of frequencies, the transducer comprising a first plurality of electrodes on a first side of the piezoelectric layer and a second plurality of electrodes on a second side of the piezoelectric layer opposite the first side, the first and second pluralities of electrodes being arranged to form two or more electrode pairs positioned along a length of the transducer, each electrode pair comprising a first electrode of the first plurality of electrodes and a second electrode of the second plurality of electrodes;
• a controller adapted to determine a subset of frequencies from the range of frequencies at which to output vibrations, and select, for the subset of frequencies, a respective input voltage for each of the two or more electrode pairs based on a relative position of each pair on the transducer, wherein respective input voltages for at least two of the two or more electrode pairs are different;
• and
• a drive module in electrical communication with each of the two or more electrode pairs, the drive module being adapted to apply the respective input voltage to each of the two or more electrode pairs to cause the transducer to generate a vibrational force on the load within the range of output frequencies,
• wherein, in order to generate the vibrational force on the load within the range of output frequencies, the transducer is configured to undergo vibrations which displace the piezoelectric layer by varying amounts along the length of the transducer, and
• wherein the controller is adapted to select the respective input voltages so as to reduce an activation of a piezoelectric response at a location on the transducer corresponding to an electrode pair where the activation is out of phase with a displacement of the piezoelectric layer.