Dielectric elastomer loudspeaker driver

Dielectric Elastomers (DE) offer promising benefits for acoustic applications due to their large achievable strain, high energy density and small response time. Although the usage for loudspeakers is often mentioned, only few concepts have been developed and realized. Most prominent are speakers based on vibrating DE-diaphragms. However, these speakers are not competitive to conventional electrodynamic speakers so far. The main reason is their inability to produce significantly large sound pressure levels due to their low mechanical and acoustical impedance. We investigate and realize an alternative approach to loudspeakers based on DE. The driving unit of the speaker is a core-free rolled DE-actuator with improved electrical contacts for optimized frequency response and reliability. An electromechanical network model is designed to describe the actuator's dynamic behavior. The network parameters are determined by extensive measurements with different mechanical loads and bias voltages. The model is extended to the acoustical domain introducing a speaker cone and enclosure. Due to the gyratory behavior of the radiating surface the mechanical behavior can be transformed to maximize the sound power output. This approach allows the realization of DE-based speakers for a versatile range of applications with many benefits to conventional concepts.