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Patents on electrostatic loudspeakers

Patents

Patent number Description Filed
Granted
Available
U.S. Patent 1,550,381 Joseph Masolle, Hans Vogt and Josef Engl assignors to Tri-Ergon Ltd., of Zurich, Switzerland "Electrostatic Telephone" Nov. 28, 1921
August 18, 1925
 
unknown Andre Charlin... receiving a patent for a push-pull electrostat... 1926  
U.S. Patent 1,622,039 Frederick W. Lee, Owing Mills, Maryland. "Apparatus for and Method of Reproducing Sound". May 2, 1925
March 22, 1927
 
U.S. Patent 1,631,583 John Depew, of New York. "Capacitatively Actuated Loudspeaker". February 12, 1926
June 7, 1927
 
U.S. Patent 1,674,683 Walter Hahnemann, Kitzberg, Germany, assigned rights to Lorenz Aktiengesellschaft. "Arrangement for Uniform Electrical Sound Transmission". March 24, 1926
June 26, 1928
 
U.S. Patent 1,762,981 Ralph V.L. Hartley of South Orange, N.J. assigned rights to Bell Telephone Labs., N.Y. "Acoustic Device" June 6, 1928
June 10, 1930
 
G.B. Patent
346,646
Edward Washburn Kellogg, Schenectady, N.Y. assigned rights to General Electric Co. N.Y. "Production of Sound" Sept. 27, 1929
April 16, 1931
 
G.B. Patent
370,248
Albert Rauser and Wilhelm Steuer, of Kottbuser-Ufer 39/40, Berlin, S.O. 26 "Improvements Relating to Electrostatic Loud-speakers". June 1, 1931
April 07, 1932
 
G.B. Patent
372,649
Hans Vogt, Genthinerstrasse 17, Berlin, W. 35, Germany. "Improvements Relating to the Insulation of Fixed Electrodes of Electrostatic Loudspeakers" Sept. 8, 1930
May 12, 1932
 
U.S. Patent 1,881,107 Hans Vogt of Berlin-Wilmersdorf, Germany. "Sounding Condenser" Sept. 15, 1928
Oct. 4, 1932
 
U.S. Patent 1,930,518 Jurjen S. High of Camden, N.J. assigned rights to Westinghouse Electric and Manufacturing Co. Pennsylvania. "Electrostatic Loudspeaker" July 30, 1930
October 17, 1933
 
U.S. Patent 1,983,377 Edward Washburn Kellogg, Schenectady, N.Y. assigned rights to General Electric Co., N.Y. "Production of Sound" Sept. 27, 1929
December 4, 1934
 
G.B. Patent
610,297
Etablissements S.M. Body Corporate of 26 Rue de Lagny, Paris. "Improvements in Electrostatic Microphones and Loud-speakers" April 9, 1946
Oct. 13, 1948
 
U.S. Patent 2,631,196 Arthur A. Janszen, Cambridge, Mass. "Electrostatic Loud-Speaker" 7 claims. Description of an ESL that has on fixed electrode, and electrically divided diaphragm to control directivity, frequency response, and impedance of the speaker. October 5, 1949
October 5, 1953
 
U.S. Patent 2,796,467 Winston E. Kock, Basking Ridge, N.J., assigned rights to Bell Telephone Labs., N.Y. "Directional Transducer" Dec. 12, 1951
June 18, 1957
 
U.S. Patent 2,855,467 Paul Curry, New Haven, Connecticut assigned rights to Curry Electronics Inc., New Haven, Conn. "Loudspeakers" Dec. 11, 1953 October 7, 1958  
 
U.S. Patent 2,864,899 Henry W. Parker, Flushing, N.Y. "Transducer" Nov. 29, 1954
Dec. 16, 1958
 
U.S. Patent 2,896,025 Janszen, Describes and ESL manufacturing process using wire grid fixed electrodes, one on either side of the diaphragm. ...
July 1959
 
G.B. Patent
815, 978
Peter James Walker and David Theodore Nelson Williamson October 19, 1955
July 8, 1959
 
U.S. Patent 3,008,013 or 3,008,014 David Theodore Nelson Williamson, Edinburgh, Scotland assigned rights to Ferranti Ltd., London. Peter James Walker of Huntingdon, England. "Electrostatic Loudspeakers" Describes a method of makig ESLs with low distortion and a method of separatng them into different sections to reproduce different frequency ranges. July 15, 1955
November 7, 1961
 
U.S. Patent 3,008,014 David Theodore Nelson Williamson, Edinburgh, Scotland assigned rights to Ferranti Ltd., London. Peter James Walker of Huntingdon, England. "Electrostatic Loudspeakers" Sept. 12, 1957
November 7, 1961
 
U.S. Patent 3,014,098 Malme, Provides a good, detailed description of ESL operation, and a design that incorporates segmented stators to control directionality at high frequencies. ...
December 1961
 
U.S. Patent 3,668,335 Beveridge, Describes a servo controlled ESL mounted in an enclosure, to allow low frequency reproduction, and with an acoustic lens to control high frequency dispersion. Patent includes schematics of vacuum tube servo control amplifier. ...
June 1972
 
G.B. Patent 1,234,767 (Willy Lefevbre, June 2001) Enock, Describes electrostatic transducers in which the stators are insulated to allow the use of high operating voltages, thereby increasing the sensitivity of the transducers. ...
June 1971
Available on exchange basis  
G.B. Patent 1,239,658 Bowers and Greenwood, Describes an electrostatic speaker that is built used printed circuit techniques, in which the stators are insulated to allow the use of high operating voltages, thereby increasing the sensitivity of the drivers. ...
July 1971
 
U.S. Patent 3,668,336 Wright, Describes an ESL with electrical connections on one side of the speaker only. ...
June 1972
 
U.S. Patent 3,778,562
(Willy Lefevbre)
Wright, Describes an ESL mounted in a sealed enclosure filled with a gas that acts as an acoustic lens to control the directionality of the driver and allows higher operating voltages than would be possible in air, thus increasing the sensitivity of the driver.. ...
December 1973
Available on exchange basis
U.S. Patent 3.773.976
Beveridge,Electrostatic loudspeaker and amplifier June 5, 1972 November 20, 1973
Available on exchange basis  
U.S. Patent 3.980.829
Beveridge,Loudspeaker and stereophonic system employing hemicylindrical wave form generators, in which the vertical extent of the speaker includes and spans the levels of seated and erect standing listeners, approximating a floor to ceiling height. Two such speakers are placed in a room, directed toward each other and spaced from an end wall, with arc of sound emission of each such that the listener region receives direct sound and two first order reflections, from side and end walls, from each of the two speakers. The path lengths are shown different in length greater than the minimum separate-source discrimination time. June 5, 1973
September 14, 1976
Available on exchange basis  
U.S. Patent 3,992.585
Turner; Elliott, Grodinsky and Mills Describes a power supply for generating polarizing voltages for the drivers on an electrostatic speaker system includes a charging circuit which charges a battery from the applied audio signal. A dc-to-dc converter generates the relatively high polarizing voltages from the battery voltage and it includes an oscillator which generates an alternating voltage to a voltage multiplier circuit. An electronic switch circuit turns the oscillator on when an audio signal is present and turns it off a preselected time interval after the audio signal is removed. October 6, 1975
Novmeber 16, 1976
Available on exchange basis  
U.S. Patent 4.270.023
Beveridge, A loudspeaker (10) has a vertically-elongated cylindrical cabinet which houses both a waveform generator (54) and a pair of sub-woofers (46, 48). The sub-woofers (46, 48) are situated near the top and bottom of the cylindrical cabinet and generate a uniform low frequency response which has in-time coherence with a cylindrical wavefront produced by the generator (54). May 31, 1979
May 26, 1981
Available on exchange basis  
U.S. Patent 4,289,936 Civitello, Describes an interesting inverse ESL with one perforated stator plate and two diaphragms on either side of it. The drivers are triangular, with multiple units assembled into a kind of geodesic dome structure for control of directivity of the speaker. ...
September 1981
 
U.S. Patent 4.323.736 (Frank Geissler, June 2003) Strickland, James C., Describes an audio step-up circuit for driving an electrostatic loudspekaer of full-range-element configuration from a low voltage, low impedance, audio signal source utilizestwo especially designed audio transfomers in parallel-bilateral interconnectionincluding R-C networks... August 11, 1980
April 6, 1982
Available on exchange basis  
U.S. Patent 4,324,950, Strickland, James C. Patent is for the ServoCharge Amplifier design. June 25, 1975
April 13, 1982
Available on exchange basis 
U.S. Patent 4,703,509 Kanchev, Describes an ESL that uses stators with resistive properties to control frequency response and directivity. ...
October 1987
 

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