Usound Gmbh

Continental Automotive Gmbh

Sensordynamics Ag

Drago Strle

Ferruccio Bottoni

Andrea Rusconi Clerici Beltrami

Volker Kempe

Lothar Gier

A method for operating a piezoelectric speaker for generating sound waves in the audible wavelength spectrum and/or in the ultrasonic range includes at least partially charging a piezo actuator of the piezoelectric speaker with electrical energy of an energy unit and then at least partially discharging the piezo actuator. The method also includes determining at least one present electrical piezo actuator voltage of the piezo actuator. A future input voltage for the piezo actuator is compared with the present electrical piezo actuator voltage prior to charging and/or discharging, and a future differential voltage is derived therefrom. Furthermore, an embodiment of the method can include returning a part of the energy needed to charge the piezo actuator to the energy unit during discharging.

Method for operating a piezoelectric speaker

A device and a method for audio signal processing for a piezoelectric speaker for generating sound waves in the audible wavelength spectrum includes a signal input for a digital audio signal, a digital correction unit for correcting a nonlinearity of the speaker, a digital PWM generator that converts the signal corrected by the correction unit into a pulse-width modulated switch signal, a power stage controllable by the switch signal such that the speaker can be charged with a voltage for deflecting a membrane, and a closed-loop control circuit that feeds the voltage back as a feedback signal, which includes a first signal noise in the audible frequency range. The closed-loop control circuit of the device includes a noise shaping unit in that shifts a noise energy of the first signal noise outside of the audible frequency range.

Device for audio signal processing for a piezoelectric speaker

An arrangement for measuring a rate of rotation using a vibration sensor, being excited and measured by means of capacitive drive elements, and the rotation of said sensor in an axis, excited by a rotation in another axis by means of the Coriolis force, being measured by means of capacitive measuring elements. Excitation voltages can be supplied to the fixed electrodes of the drive elements, the frequency of said voltages corresponding to the resonance frequency or the subharmonic of the resonance frequency of the vibration sensor. An alternating voltage having a first measuring frequency which is higher than the excitation frequency can be supplied to capacitive elements for measuring the excited vibration. Alternating voltages having a second measuring frequency higher than the excitation frequency are supplied to the fixed electrodes of the measuring elements can be supplied to drive elements causing a vibration excitation in a direction on the basis of the excitation voltage, being in antiphase with the excitation voltage.

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Ljubljana, Slovenia

Drago Strle