ELECTROACOUSTIC TRANSDUCER UNIT WITH REDUCED RESONANT FREQUENCY AND MECHANICAL SPRING WITH NEGATIVE STIFFNESS, PREFERABLY USED IN SUCH A TRANSDUCER UNIT

摘要

An electroacoustic transducer unit comprises an electroacoustic transducer with a diaphragm (1), a magnet system (2) with an air gap (3), and a voice-coil former (4) with a voice coil (5) arranged in the air gap (3) of the magnet system. The transducer unit comprises means for reducing the transducer resonant frequency including mechanical springs with negative spring stiffness each coupled between a stationary part of the transducer unit and a movable part, for example the voice-coil former or the diaphragm of the transducer (FIG. 1b). The transducer unit further comprises a control device (42) which generates a control signal for correcting the position of the diaphragm. The mechanical spring with negative spring stiffness comprises two blade springs with both ends coupled to each other and which, under the influence of a compressive force F which acts in a direction along an imaginary line through both ends of the mechanical spring, are each bent in one of two opposite directions.