(12) United States Patent ao) Patent No.: us 6,178,353 Bi
Griffith et al. (45) Date of Patent: Jan. 23,2001
(54) LAMINATED MAGNET KEEPER FOR IMPLANT DEVICE
(75) Inventors: Glen A. Griffith, Newbury Park;
Richard P. Malmgren, Castaic, both of
(73) Assignee: Advanced Bionics Corporation,
Sylmar, CA (US)
( * ) Notice: Under 35 U.S.C. 154(b), the term of this patent shall be extended for 0 days.
(21) Appl. No.: 09/353,236
(22) Filed: Jul. 14, 1999
Related U.S. Application Data
(60) Provisional application No. 60/094,300, filed on Jul. 27, 1998.
(51) Int. CI. A61N 1/378
(52) U.S. CI 607/61
(58) Field of Search 607/33, 61, 57,
(56) References Cited
U.S. PATENT DOCUMENTS
5,690,693 * 11/1997 Wang et al 607/61
An implantable medical device, such as an implantable cochlear stimulator (ICS) system, utilizes laminated, sectionalized or particle-ized permanent magnets and/or keepers in both the implant portion and external (non-implanted) portion so as to reduce the electrical energy absorbed by both the implant device and the external device when in use. In one embodiment, the implant device employs a sectionalized, laminated or particle-based "keeper", while the external device employs a sectionalized, laminated or particle-ized magnet, making the implant device immune to being damaged by MRI (magnetic resonance imaging). The combination of the sectionalized/laminated/particle magnets and the sectionalized/laminated/particle keepers creates a very high electrical resistance path across the boundaries of the laminations, sections, or particles, thereby reducing the magnitude of eddy currents that would otherwise flow transversely through the keeper in the presence of a magnetic flux passing through the keeper or magnet. The reduction of eddy currents, in turn, reduces energy loss.
20 Claims, 5 Drawing Sheets