Absolute encoder scale with plates repeatedly arranged against changing notches

摘要

An absolute position encoder scale is provided having scale elements (e.g., plates and plate abatement features such as recesses) which alternate along the scale pattern. At least one of the scale elements has a characteristic (e.g., a recess depth) that is varied along the scale pattern to provide a different respective eddy current response. A signal portion of a read head is responsive to the respective eddy currents to output absolute position signals. For the plate abatement features, the characteristic that may be varied may be a recess depth, an amount of a non-conductive area, an amount of a recessed area, etc. As a varying depth example, the scale may be formed from a bulk material (e.g., aluminum) in which progressively deeper recessed depths are cut along the scale. For plate features, the characteristic that may be varied may include a plate height, an amount of a plate area, etc.