Motorola Corporation

Harold W Mech

Lawrence N Dworsky

Jeffery A Whalin

Leo V Krolak

Emory Wakat, Jr

James R Phillips

Dale G Hall

Donald W Forst

Gary L Vaughn

A piezoelectric transformer with voltage feedback is disclosed. The transformer comprises a piezoelectric plate of predetermined length, width and height with a driving section formed by alternately stacking a plurality of piezoelectric ceramic layers having internal interdigitated electrode layers. A driven section including an unpolarized dielectric section, a voltage feedback section in the form of a multilayer electrode structure or an outer strip, and a normally polarized dielectric section is also disclosed. The transformer generates an output voltage at an output terminal by the piezoelectric vibration transmitted from the driving section. A feedback control circuit is connected to the voltage feedback section. The isolated voltage feedback provides feedback control to keep the transformer operating at the proper resonant frequency even as there is a change in output load of the transformer.

Piezoelectric transformer with voltage feedback

A circuit (10) for driving a piezoelectric transformer (12) in a phase locked mode without using an external reference signal. The circuit (10) utilizes a 555 timer circuit operated in a stable mode which is responsive to a feedback phase signal (18) coupled from an output signal (20) of the piezoelectric transformer (12). The feedback phase signal (18) overpowers the trigger circuit of the timer to phase lock the timer to an output of the piezoelectric transformer (12) at a resonant frequency of the piezoelectric transformer (12). The circuit (10) provides a simplified phase lock circuit without the need for a typical PLL configuration.

Single-input phase locking piezoelectric transformer driving circuit

A method and apparatus for controlling the sound pressure levels of a substantially capacitive speaker. The controlling element is substantially capacitive and may be either fixed or variable.

Speaker power matching method and apparatus

A crystal is mounted on a low, centrally located pedestal. Connections to the lower side of the crystal are made by way of conductive areas on the pedestal. Multiple wiring connections are made at the edges of the crystal by allowing the bonding tool to depress the edge of the crystal so that the crystal bonding pad is supported by the base structure only during the bonding process, then released thereafter to allow free vibration of the crystal plate. Complex circuitry, possibly involving more than one frequency can thus be put onto one plate.

Growing community of inventors

Albuquerque, NM, United States of America

Harold W Mech