1979-08-24
1981-03-24
Robinson, Thomas A.
H04R 1302
Patent
active
042582342
ABSTRACT:
Electroacoustic devices are disclosed which comprise a permanent magnet and a magnetically permeable component. The permanent magnet is made of an Fe-Cr-Co alloy comprising 20-40 weight percent Cr and 3-30 weight percent Co; the permeable component is made of an Fe-Al alloy comprising 1.5-18 weight percent Al.
In addition to a magnetic circuit, disclosed devices comprise means such as, e.g., an induction coil for inducing a variable magnetic field in the magnetic circuit. Also, devices comprise means for utilizing energy output in response to the magnetic field. Energy output may typically be in the form of an acoustical signal having desirably flat frequency response. Due to their low cost, disclosed devices are particularly suitable for use in telephone receivers and other mass produced articles.
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"Ferromagnetism", by Bozorth, Van Nostrand, 1959, pp. 210-220.
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"Recent Developments in Soft Magnetic Alloys", Adams, J. Appl. Phys., Supp. vol. 33, No. 3, Mar. 1962, pp. 1214-1220.
"Sendust Sheet-Processing Techniques and Magnetic Properties", Helms, Jr., J. Appl. Phys., vol. 35, No. 3, Mar. 1964, pp. 871-872.
"Magnetic Properties of Oriented 3 Percent Aluminum Iron Sheets", Foster et al., J. Appl. Phys., vol. 34, No. 4, (Part 2), Apr. 1963, pp. 1325-1326.
"Alloys with Low Remanence and Low Coercive Force in the Region of 9% Aluminum Iron", Pavlovic et al., J. Appl. Phys., vol. 36, No. 3, Mar. 1965, pp. 1237-1239.
Bordelon Chester M.
Sherwood Richard C.
Bell Telephone Laboratories Incorporated
Businger Peter A.
Robinson Thomas A.
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