Patent ID: 7339448

Claim:
An encoder target wheel, comprising (a) a continuous ring of cured magnetizable polymer cured from an admixture comprising (i) a continuous phase of an elastomeric thermoplastic selected from the group consisting of polyester thermoplastic elastomer, polyamide thermoplastic elastomer, acrylic acid ester rubber/polyacrylate rubber thermoplastic vulcanizate, ethylene acrylic rubber thermoplastic vulcanizate, silicone-thermoplastic vulcanizate, thermoplastic polyurethane vulcanizate, thermoplastic polyurethane vulcanizate/polyamide thermoplastic elastomer, and combinations thereof, and (ii) a first dispersed phase of magnetizable particulate dispersed in said continuous phase, and (iii) a second dispersed phase of hydrophobic material dispersed in said continuous phase, the hydrophobic material comprising ethylene-vinyl acetate copolymer, and the hydrophobic material being present in the admixture in an amount not greater than about twice the weight of said elastomeric thermoplastic; (b) at least one first magnetized portion in said continuous ring, said first magnetized portion having a first magnetic field strength; and (c) at least one second portion in said continuous ring, said second portion having a second magnetic field strength differentiated from said first magnetic field strength by not less than about 200 Gauss when measured across an air detection gap of about 1 mm; (d) wherein said admixture provides an elastic elongation property of not less than about 50 percent at break and a water swell property of not greater than about 10 percent in said encoder target wheel.