Patent ID: 8633703
Filing Date: 2014-01-21
Classification: G01N

Abstract:
1. A conductivity sensor for measuring conductivity of a medium surrounding the conductivity sensor, comprising: a first toroidal coil, which surrounds a first traversing opening for accommodating the medium and which serves for inducing an electrical current in the medium; and a second toroidal coil, which surrounds a second traversing opening for accommodating the medium and for registering a magnetic field produced by the induced electrical current, wherein: at least one of said toroidal coils has a plurality of first conductor sections, which extend in a first plane of a multi-ply circuit card, a plurality of second conductor sections, which extend in a second plane of said circuit card, and a plurality of vias, which connect said first conductor sections with said second conductor sections; said first conductor sections, said second conductor sections and said vias together form the windings of said first toroidal coil; said at least one toroidal coil is surrounded by a plurality of internally metallized bores, which are arranged in such a manner, that they act as electrical shielding of said toroidal coil; said internally metallized bores extend essentially parallel to said vias, especially wherein said bores and said vias extend essentially perpendicular to the plies of said circuit card; said plurality of internally metallized bores comprise internally metallized bores of a first type, which are arranged along an essentially closed ring surrounded by said at least one toroidal coil and extend around said traversing opening surrounded by said toroidal coil; in at least one additional third plane of the circuit card, an electrical shielding ply, especially of an electrically conductive material, especially copper, is arranged; said at least one toroidal coil is arranged in the stack direction of said circuit card before or behind said shielding ply; in the third plane of said circuit card, a first electrical shielding ply is arranged and, in an additional, fourth plane of said circuit card, a second electrical shielding ply is arranged; said at least one toroidal coil with reference to the stack direction of said circuit card is arranged between said first and second shielding plies; each of said internally metallized bores of said first type is directly connected with only one of said electrical shielding plies; and said internally metallized bores of second type connect said first and second electrical shielding plies with one another.