3,946,422

43.88.Bs ELECTRET TRANSDUCER HAVING AN ELECTRET OF INORGANIC INSULATING MATERIAL

Hajime Yagi, Yoshihiro Saito, Koji Himno, assignors to Sony Corporation

23 March 1976 (Claim 357/26); filed in Japan 2 December 1971

At the present time, most commercially successful electret biased capacitance transducers use organic high polymer materials. This microphone depends on a vapor deposited inorganic insulating material, such as silicon dioxide, to retain the electric charge.-MDB

3,980,838

43.88.Bs PLURAL ELECTRET ELECTROACOUSTIC TRANSDUCER

Nobou Yakushiji and Kenji Suehiro, assignors to Tokyo Shibaura Electric Company

14 September 1976 (Claim 179/111 E); filed in Japan 20 February 1974

Two electret film diaphragms are used, one on either side of a common backplate electrode. Holes through the backplate elec- trode allow the device to operate as a balanced transducer.-MDB

3,935,398

43.88.Dv TRANSDUCER WITH IMPROVED ARMATURE AND YOKE CONSTRUCTION

Elmer V. Carlson, August F. Mostardo, Jr., and Alex V. Diblick, assignors to Industrial Research Products, Incorporated

27 January 1976 (Class 179/119 A); f'fied 12 July 1971

The transducer is intended as an output for hearing aids and similar applications. The construction lends itself to a unit with

very small height. As shown in the cross-section drawing, the coil assembly 23, the magnet pole piece stack 29, and the diaphragm assembly 39 are all positioned essentially in the same line, and the vibrating end of the armature 60 is attached directly to plate 59 on the diaphragm 39. Pressure created in volume 51 is transmitted outward through opening 17 and tube 20.-MDB

3,935,484

43.88. Fx REPLACEABLE ACOUSTIC TRANSDUCER ASSEMBLY

Walter C. Leschek and Philip E. Carpentier, assignors to Westinghouse Electric Corporation

27 January 1976 (Class 310/8.2); fried 25 February 1974

This ultrasonic transducer is intended to withstand high temp- erature and high radiation flux levels associated with atomic reac- tors. It is contained in a tubular enclosure and has a transducer

window that seals one end and will be placed in contact with the test object. It is held to the test object or surface by means of a compressed spring arrangement. Materials of fabrication approp- riate to the environment are indicated, including lead zirconate- titanate piezo-ceramic elements.-MDB

3,941,6 29

43.88.Gy DIAPHRAGM FORMATION ON SILICON SUBSTRATE

James M. Jaffe, assignor to General Motors Corporation 2 March 1976 (Claim 156/8); filed 11 April 1'974

A method of making thin diaphragms having an accurately con- trollable thickness for semiconductor pressure responsive devices is described. An oxide coating is thermally grown in selected regions on the front side of a silicon wafer. The oxide extends into the

wafer to an extremely accurate and controllable depth to form a groove in the wafer front side. Portions of the wafer are then etched from the back side until the bottom of the groove is reached, thereby providing a diaphragm having a thickness equal to the accurately reproducible depth of the groove.-MDB

4,223,760

43.88.Ja LOUDSPEAKER ASSEMBLY

Ted I. LeToumeau, Longview, Texas 75602 23 September 1980 (Class 181/147); filed 24 April 1978

Because of its inherent rigidity, a cylinder can be used to make a lightweight loudspeaker enclosure. This observation seems to occur to some inventor every six months or so. Obviously, loudspeakers can be mounted at the ends of a cylinder, and there must be a doz- en patents dealing with such designs. This invention falls into the other subclass: Loudspeakers are mounted to the cylindrical face with their respective axes offset 15 to 25 degrees.-GLA

4,224,467

43.88.Ja CORNER MOUNTED SOUND REPRODUCTION SPEAKER APPARATUS

Andrew G. Lewis, Des Plaines, Illinois 60016 and Bernard L. Kleinke, Palatine, Illinois 60067

23 September 1980 (Class 179/1 E); filed 26 June 1978

For how many years, in how many commercial sound catalogs, have simple corner loudspeaker enclosures been available? The in- ventors have patented the concept.-GLA

4,224,469

43.88.Ja STEREO SPEAKER SYSTEM

Theodore R. Karson, Chicago, Illinois 60634 23 September 1980 (Class 179/1 E); filed 2 January 1979

A single loudspeaker cabinet houses a big, folded transmission line for the woofer, a medium-size transmission line for the mid- range unit, and a little-bitty transmission line for the tweeter. The inventor's notion of a transmission line for the woofer is a folded

pipe roughly 2m in effective length with a sliding panel to adjust vent area at its far end. This configuration "... absorbs stored or lagging energy which distorts the sound." and allows, "... frequen- cies in the range below 20 Hz to be accurately reproduced."-GLA

4,227,047

43.88.Ja DOME STRUCTURE

Edward A. Home, Jacksonville, North Carolina 28540 7 October 1980 (Class 179/1 E). filed 21 July 1978

A dome structure, roughly the shape of a quarter of a melon, is intended to serve as a listening booth for auditioning stereo com- ponents. In the corner of the booth, in front of the listener, is a rack full of electronic components. Mounted into the surface of the dome behind him are many pairs of loudspeakers. Such a struc- ture is claimed to be inexpensive, attractive, and easy to install.

623 J. Acoust. Soc. Am. 69(2), Feb. 1981; 0001•,966/81/020623-02500.80; ¸ 1981 Acoust. Soc. Am.; Patent Reviews 623

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