Patent ID: 8203334

Claim:
A magnetically spirally encoded shaft, comprising a first band comprising first magnetically encoded regions having a first magnetic polarity alternating with second magnetically encoded regions having a second magnetic polarity; a second band comprising the second magnetically encoded regions alternating with the first magnetically encoded regions, wherein the first band is spaced apart from the second band such that first magnetically encoded regions in the first band are opposite second magnetically encoded regions in the second band and second magnetically encoded regions in the first band are opposite first magnetically encoded regions in the second band, a force-sensitive region between the first and second magnetically encoded regions, magnetic fields present above each force-sensitive region; wherein the first and second bands are disposed in a spiral shape around a shaft circumference; a third band comprising the first magnetically encoded regions alternating with the second magnetically encoded regions; a fourth band comprising the second magnetically encoded regions alternating with the first magnetically encoded regions, wherein the third band is spaced apart from the fourth band such that first magnetically encoded regions in the third band are opposite second magnetically encoded regions in the fourth band and second magnetically encoded regions in the third band are opposite first magnetically encoded regions in the fourth band, force sensitive regions between the first and second magnetically encoded regions of the third and fourth bands; wherein the first band defines first dead zones between each of the first and second magnetically encoded regions aligned with second dead zones between each of the first and the second magnetically encoded regions in the second band, wherein each of the first and the second dead zones is axially aligned with a force-sensitive region between the third and fourth bands; and wherein the third band defines third dead zones between each of the first and second magnetically encoded regions axially aligned with fourth dead zones between each of the second and first magnetically encoded regions in the fourth band, wherein each of the third and fourth dead zones are axially aligned with a force-sensitive region between the first and second bands, the shaft for use with a first fixed magnetic field sensor for detecting magnetic fields in the force-sensitive regions.