EP 0339820 A3 19910320 - ELECTROMAGNETIC TRANSDUCER
Title (en)
ELECTROMAGNETIC TRANSDUCER
Publication
Application
Priority
GB 8809805 A 19880426
Abstract (en)
[origin: EP0339820A2] In a moving coil electro magnetic transducer, a top plate (12), a back plate (16) and a pole piece (18) of the magnetic circuit of a magnet (14) may act as a shorted secondary coil around a moving coil (24). To prevent current flow in such a secondary coil wasting energy, the invention provides that at least one and preferably all such components are made electrically discontinuous by providing them with a radial slit (20) thereby to reduce energy dissipated by induction.
IPC 1-7
IPC 8 full level
H04R 9/02 (2006.01)
CPC (source: EP)
H04R 9/025 (2013.01); H04R 2209/043 (2013.01)
Citation (search report)
- [Y] DE 2131035 A1 19730111 - MAGNETFAB BONN GMBH
- [A] US 4293741 A 19811006 - DIGRE CLIFFORD B
- [A] US 4295011 A 19811013 - HATHAWAY DANA B
- [A] FR 858268 A 19401121 - HENRY HUGUES & SON
- [E] EP 0339855 A2 19891102 - SONY CORP [JP]
- [X] PATENT ABSTRACTS OF JAPAN, vol. 5, no. 78 (E-58)[750], 22nd May 1981; & JP-A-56 27 600 (OSANORI KISHI) 17-03-1981
Designated contracting state (EPC)
AT BE DE ES FR GB IT NL SE
DOCDB simple family (publication)
EP 0339820 A2 19891102; EP 0339820 A3 19910320; AU 3301289 A 19891102; GB 8809805 D0 19880602; JP H01318399 A 19891222
DOCDB simple family (application)
EP 89303509 A 19890410; AU 3301289 A 19890413; GB 8809805 A 19880426; JP 10184489 A 19890424