Integrated circuit transponder with coil antenna in a pneumatic tire for use in tire identification

Claim 1

A pneumatic tire having an integrated circuit transponder located within the structure of the tire for use in tire identification or data transmission, the tire having two spaced beads respectively including an annular tensile member of wound or cabled steel wire, the tire having a tread, sidewalls, an innerliner and a plurality of plies at least one of which is a continuous ply extending between the annular tensile members, respective ends of the continuous ply being turned axially and radially outwardly about the annular tensile members, the transponder having separate first and second electrodes and an antenna having first and second leads connected respectively to the first and second electrodes of the transponder, the transponder being able to transmit an electrical signal in response to an oscillating electromagnetic field emanating from a source in contact with or spaced from the tire, the pneumatic tire and transponder being characterized by: the antenna comprising an electrical coil having a plurality of bunched turns and an area enclosed by such turns, the perimeter of the area being defined by the closed curve formed by the locus of points centered within the bunched turns, the area being circular or oblong with a diameter or maximum dimension across the area, the maximum dimension being greater than or equal to the cross sectional dimension of the bunched turns in the direction perpendicular to the area enclosed by the turns of the coil, the coil being positioned as a secondary winding associated with one of the annular tensile members as a primary winding, the coil being positioned between the inner and outer surfaces of the tire in a location at least partially overlapping the end of the continuous ply turned about the primary winding, the coil area being substantially less than the area enclosed by the primary winding annular tensile member, such coil and member having different axes such that the coil has a varying relationship with respect to points on the sidewalls and tread of the tire, the oscillating electromagnetic field to which the transponder is responsive during interrogation enabling a magnetic field component to pass through the area enclosed by the primary winding annular tensile member causing a magnetic field to encircle the primary winding, a portion of the magnetic field encircling the primary winding passing through the area enclosed by the turns of the coil, thereby, when the magnetic field is sufficiently intense, enabling transmission of the transponder's electrical signal via the antenna.