Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
1998-03-04
2001-04-03
Budd, Mark O. (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C310S334000, C310S337000, C310S369000
Reexamination Certificate
active
06211601
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates generally to acoustic projectors, and more particularly to a system and method for operating acoustic projectors over a wide bandwidth while reducing the power supplied and dissipated.
(2) Description of the Prior Art
Acoustic projectors of the type having multiple ceramic elements are used to provide wide bandwidth operation. Such projectors are normally powered by an amplifier tuned to the center of the frequency band of operation. For example, U.S. Pat. No. 4,652,786 to Mishiro recites a torsional vibration apparatus having a plurality of electrodes formed on the two surfaces of a circular member of electrostrictive material. Adjacent electrodes are simultaneously polarized so as to be mutually reversed in a circumferential direction. The electrodes essentially form multiple elements from the circular member. A high frequency voltage is tuned to the slide resonance frequency and impressed on the apparatus to induce resonant vibration. The electrodes are connected to a power supply through a transformer having the primary coil connected to the power supply, the midpoint of the secondary coil connected to ground and the ends of the secondary coil connected to the segmented electrodes in an alternating manner such that adjacent electrodes have opposite polarity. In a stack configuration, the ends of the secondary coil would be connected at each end of the stack. The power amplifier load at the frequency band edges is highly reactive with a large phase angle. This results in the power amplifier and its power source supplying substantial amounts of reactive power to the projector, with power being dissipated in the amplifier. A need exists to operate acoustic projectors more efficiently over a wide bandwidth.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a system and method to operate an acoustic projector more efficiently over a wide bandwidth.
Another object of the present invention is to provide a system and method to operate an acoustic projector which reduces the power dissipated in the amplifiers.
Still another object of the present invention is to provide a system and method to operate an acoustic projector which reduces the power supply requirements of the projector.
Other objects and advantages of the present invention will become more obvious hereinafter in the specification and drawings.
In accordance with the present invention, a system and method for operating an acoustic projector is provided which allows efficient operation of the projector over a wide bandwidth. The system and method use multiple tuning network assemblies each operating over separate and narrow bandwidths. Each tuning network assembly has a power amplifier, a transformer and a tuning inductor. The tuning inductor for each tuning network assembly is selected for proper tuning over the frequency bands for that assembly. The number of separate bandwidths corresponds to the number of amplifiers such that the total bandwidth is covered. As is well known in the art, the narrower bandwidths for each power amplifier will result in substantial reductions in the reactive power dissipated in the amplifiers and also in the total power consumption of the acoustic projector.
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Budd Mark O.
Gauthier Robert W.
Lall Prithvi C.
McGowan Michael J.
The United States of America as represented by the Secretary of
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