Patent ID: 6931283

Claim:
A biocompatible housing for an implantable tissue stimulating device having an electrode lead with an electrode: said housing being adapted for connection to said electrode lead and said stimulating device generating a voltage between said housing and said electrode, said voltage having an electric field associated therewith, said housing comprising: a first wall having a generally flat first exterior surface, said first wall being adapted to face the skin of a patient when said housing is implanted; a second wall having a generally flat second exterior surface; and a circumferential third wall joining said first wall and said second wall, said third wall being composed of conductive material and adapted for electrical contact with surrounding tissue when said housing is implanted to serve as an electrode, said third circumferential wall having a curved first circumferential wall section connected to said first wall and a curved second circumferential wall section connected to said second wall and substantially opposing circumferential wall portions between said curved first and second wall sections, said first circumferential wall section having a radius of curvature smaller than a radius of curvature of said second wall section, for curve radii in planes substantially perpendicular to said first surface and said second surface, causing said electric field to have a lower field strength along said second circumferential wall section than along said first circumferential wall section and a spacing between the first wall and second wall being less than a spacing between said substantially opposing wall portions of the circumferential third wall.