4,385,209

43.88.Bs ADJUSTMENT OF OPERATING CHARACTERISTICS OF A TELEPHONE TRANSMITTER INCLUDING AN ELECTRET TRANSDUCER

bonding becomes tedious. In this patent a lattice array is utilized which can be assembled as a unit. The magnified appearance is shown in the figure. The electret layer is 14; the patterned conductors are 24; and the ground layer is 16.--RWC

William D. Greason, Beverley W. Gumb, Alan C; Busthe, and Eric Foster, assignors to Northern Telecom Limited

24 May 1983 (Class 179/111 E); filed 28 November 1980

This patent describes details of a highly perfected electret micro- phone and internal amplifier, in which the control resistor is set for a prede- termined amplification.--RWC '

4,389,580

43.88.Bs FLEXIBLE TAPE ELECTROACOUSTIC TRANSDUCER USING AN ELECTRET

Andre P. J. Bendyshe Walon, Francis H. Townsend, and John N. Ribet, assignors to C. Tape Developments Limited

21 June 1983 (Class 307/400); filed in United Kingdom 3 March 1980

A contact-type transducer is described wl•ch is comprised of a plu- rality of layers of tape. The outside layer 20 is insulation. The next inner layer' 14 is a ground-potential metal. The next layer 12 is dielectric material (not specified). The st.rip 10 in the middle is conductive metal. The inner surface 16 of the foil 14 is coated with dielectric material such as vinyl resin.

4,403,117

43.88.Bs SONIC TRANSDUCER HAVING DIAPHRAGM TENSIONING SPRING DIRECTLY ATTACHED TO DIAPHRAGM

Richard Paglia, assignor to Polaroid Corporation 6 September 1983 (Class 179/111 R); filed 4 June 1981

This patent describes an electret microphone designed especially for ultrasonic control of camera operation. The diaphragm 36 is made of polyi-

36

mide film manufactured by dupont Company, under the registered trade- mark "Kapton." The backplate 38 and tensioning structure 40 may be seen in the figure.--RWC

It appears to this reviewer that this dielectric resin constitutes the principal compliance of the transducer system. The tape so formed is sufficiently flexible to be adhered to the body of a guitar. It may alternatively be utilized to detect the sounds of cracks in structures. It has further utilization in

burglar alarms. It is apparently a low-sensitivity transducer Which responds to vibrations in the surface to which it is applied, to the relative exclusion of local ambient sounds.--RWC

4,404,489

43.88.Bs ACOUSTIC TRANSDUCER WITH FLEXIBLE CIRCUIT BOARD TERMINALS

4,327,433

43.88.Dv MAGNETIC PHONO CARTRIDGE

Keniti Okura and Kazuo Nishikawa, assignors to Pioneer Elec- tronic Company

27 April 1982 (Class 369/139); filed in Japan 25 September 1979

In this stereophonic cartridge set screw 8 may be loosened to permit axial adjustment of the armature in relation to magnet yokes 14L, 13L, and 15L. Right and left channel coils are mounted above and 45 ø to either side of a line diametrically bisecting the cantilever and in the same axis. This adjus- tability permits imbalances between output signals for either channel to be corrected. The use of such lightweight air-core coils results in reduced ar- mature mass and the usability of a softer, more compliant damper 10. An

John D. Larsen, III and David G. Miller, assignors to Hewlett- Packard Company

13 September 1983 (Class 310/334); filed 3 November 1980

There is a problem in assembling and connecting individual micro- phone elements to output circuitry, in that if there are many elements, the

effective disposition of the various elements results in a more efficient mag- netic circuit. Frame 16 is nonmagnetic. Flux emanating from the northpole

1318 J. Acaust. Sac. Am. 75(4), April 1984; 0001-4966/84/041318-02500.80; ¸ 1984 Acaust. Sac. Am.; Patent Reviews 1318

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