Flexure mode piezoelectric transducers

Although flexurally responsive piezoelectric elements have been utilized for a few decades, interest in their utility remains high. This is a result of the ability of such structures to generate high output from sources of low mechanical impedance, or conversely, to develop large displacement at low levels of electrical excitation. Typically, a bending response is obtained from a sandwich-like structure of two properly oriented piezoelectric expander plates in which case the unit is referred to as a bender Bimorph^®. However, other approaches to benders include the unimorph, the Multimorph^®, and other specially treated single-plate elements. Numerous applications utilizing bender responsive elements exist. To aid in meeting the variety of requirements presented by these applications, the supplier has available to him many options. These variables include choice of materials, geometry, and electrode configuration. In terms of volume of usage, the phonograph cartridge remains the number one application. However, many other electroacoustical devices are made possible by the availability of the Bimorph or its modified alternates. Some of these are indicated. In addition, the utility of the equivalent circuit and its constants are described.