4,469,920 43.88.Fx PIEZOELECTRIC FILM DEVICE FOR CONVERSION BETWEEN DIGITAL ELECTRIC

SIGNALS AND ANALOG ACOUSTIC SIGNALS

Preston V. Murphy, assignor to Lectret S. A. 4 September 1984 (Class 179/110 A); filed in France 9 February 1982

A piezoelectric film transducer has a number of zones that can be independently driven. Their areas are graduated by powers of two. "In operation, the amplitude of the acoustic pulse generated by the excitation of

a zone or a group of zones is proportional to the numerical size of the corresponding bit. Because the voltage applied to each metallized zone is constant, only the area of the excited zone influences the amplitude of the acoustic pulse. An analog acoustic filter allows the transformation into an analog sound signal."--GLA

4,469,976 43.88.Fx SINGLE-SIDE CONNECTED TRANSDUCER

William R. Scott, assignor to the United States of America 4 September 1984 (Class 310/334); filed 6 July 1982

This transducer employs a piezoelectric film 13 of polyvinylidene flu- oride (PVF2). Gold is sputtered on the film to form electrodes 15 and 17 on the upper side, and 18 on the lower. Electrical leads 21 and 23 are attached

to the upper electrodes only. The transducer is active in the areas 19 where the electrodes overlap and these two regions are electrically in series. The inevitable bumps for electrical connections are restricted to the upper side by this construction, and the underside is left smooth for easy attachment to a structure.--LB

4,452,333 43.88.Ja SPEAKER SYSTEM

HartIcy D. Peavey and Robert M. O'Neill, assignors to Peavey Elec- tronics Corporation

5 June 1984 (Class 181/144); filed 28 May 1982

The loudspeaker system consists of a subwoofer and a pair of satellite high-frequency loudspeakers. This is hardly an original concept. The no- velty apparently ties in an ingenious application of slot loading for the sub- woofer system. In use, the slot acts as an acoustic low-pass filter. When the system is transported it houses the two high-frequency satellites.--GLA

4,454,927 43.88.Ja REENTRANT CONE DRIVEN LOUDSPEAKER

Frederick L. Seebinger, assignor to Atlas Sound Division of American Trading and Production Corporation

19 June 1984 (Class 181/152); filed 21 December 1981

The patent describes a hybrid horn/direct radiator loudspeaker that is relatively inexpensive, yet resistant to weather conditions and vandalism. In spite of some rather questionable explanatory phrases, the operation of the system seems clear. Backward-firing speaker 54 is enclosed in conical

26 36•

chamber 62. Sound is propagated through successive chambers 86 and 88 which form a short reentrant horn. The mystery lies in how sound gets from 86 to 88. Apparently the drawings are at fault since "a spacing" between rear chamber 62 and main housing 26 is called out in the descriptive para- graphs although it is not shown in the corresponding diagram.•GLA

4,482,026 43.88.Ja LOUDSPEAKER ENCLOSURE

George D. Stehlin, Jr., Oakland, CA 13 November 1984 {Class 181/152); filed 2 December 1982

This appears to be one of those labors of love that include all sorts of baffles, deflectors, tuned columns, reflex openings, and resonant plates.

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tz

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What happens in this case is that loudspeaker backwave "energies" are developed"...almost exclusively as acoustical tensions."•GLA

1635 J. Acoust. Soc. Am. 77(4), April 1985; 0001-4966/85/041635-01500.80; ¸ 1985 Acoust. Soc. Am.; Patent Reviews 1635

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