Weighted transducer and driving circuit with feedback

An apparatus for driving a piezoelectric element comprising:

• a voltage source for supplying an input voltage signal;
• a step-up transformer for receiving and amplifying said input voltage signal to thereby generate an amplified voltage signal;
• a driving terminal for receiving said amplified voltage signal and applying said amplified voltage signal to said piezoelectric element, to thereby cause said piezoelectric element to vibrate;
• a sensing terminal connected to said piezoelectric element for sensing the vibrations of said piezoelectric element and for generating a feedback signal based on said sensed vibrations;
• bandpass filtering means for bandpass filtering said feedback signal to remove unwanted phase shifts induced by said step-up transformer;
• and
• control means for controlling supplying said input voltage to said step-up transformer based on said filtered feedback signal.

A method for driving a piezoelectric element comprising the steps of:

• generating an input voltage signal;
• amplifying said input voltage signal to thereby generate an amplified voltage signal;
• applying said amplified voltage signal to said piezoelectric element, to thereby cause said piezoelectric element to vibrate;
• sensing the vibrations of said piezoelectric element and generating a feedback signal based on said sensed vibrations;
• bandpass filtering said feedback signal;
• and
• controlling supplying said amplified voltage signal to said piezoelectric element based on said filtered feedback signal.

A sound generating device coupled to a housing, comprising:

• a vibrating device mounted to said housing and comprising:
• a piezoelectric element;
• and
• a weight mechanically coupled to said piezoelectric element;
• wherein said weight is selected such that said vibrating device and said housing to vibrate as a single unit to generate sound;
• a circuit for driving said vibrating device comprising:
• a voltage source for supplying an input voltage signal;
• a step-up transformer for receiving and amplifying said input voltage signal to thereby generate a amplified voltage signal;
• a driving terminal for receiving said amplified voltage signal and applying said amplified voltage signal to said vibrating device;
• a sensing terminal connected to said vibrating device for sensing the vibrations of said vibrating device and for generating a feedback signal based on said sensed vibrations;
• filtering means for filtering said feedback signal to remove unwanted phase shifts induced by said step-up transformer;
• and
• control means for controlling supplying said input voltage to said step-up transformer based on said filtered feedback signal.

A sound generating device coupled to a housing comprising:

• a vibrating device mounted to a mounting means and comprising:
• a piezoelectric element;
• and
• a weight mechanically coupled to said piezoelectric element,
• said mounting means being rigidly mounted to the housing:
• wherein said weight is selected such that said vibrating device, said mounting means and said housing vibrate as a single unit, the vibration of the housing thereby generating sound.