Abstract: An absolute position encoder comprises a scale and a detector overlaying the scale. The scale includes a periodic pattern of wavelength Wf and a code pattern having bit length Wcode. The detector includes a set of periodic pattern sensors and M sets of code pattern sensors. M is at least two. The configuration principles include: a) Wcode is larger than Wf and at most M*Wf, and b) the sets of code pattern sensors are located along the measuring axis at respective alignment positions configured such that as the code pattern moves in a single direction it moves by successive alignment intervals that are each at most Wf to align with successive alignment positions. Signal processing is provided to determine the absolute position based on the M respective sets of code detector signals and on spatially periodic signals arising in the periodic pattern sensing elements due to the periodic pattern.

Abstract: An inductive type position encoder includes a scale, a detector portion and a signal processor. The scale includes a periodic pattern of signal modulating elements (SME) arranged along a measuring axis, with a spatial wavelength W1. One type of SME in the pattern comprises similar conductive plates or loops. The detector portion comprises sensing elements and a field generating coil that generates a changing magnetic flux. The sensing elements may comprise conductive loop portions arranged along the measuring axis and configured to provide detector signals which respond to a local effect on the changing magnetic flux provided by adjacent SME's. In various implementations, the first type of SMEs have an average dimension DSME along the measuring axis direction that is greater than DSEN and at least .55*W1 and at most 0.8*W1, which provides advantageous detector signal characteristics.

Abstract: An absolute position encoder comprises a scale and a detector overlaying the scale. The scale includes a periodic pattern of wavelength Wf and a code pattern having bit length Wcode. The detector includes a set of periodic pattern sensors and M sets of code pattern sensors. M is at least two. The configuration principles include: a) Wcode is larger than Wf and at most M*Wf, and b) the sets of code pattern sensors are located along the measuring axis at respective alignment positions configured such that as the code pattern moves in a single direction it moves by successive alignment intervals that are each at most Wf to align with successive alignment positions. Signal processing is provided to determine the absolute position based on the M respective sets of code detector signals and on spatially periodic signals arising in the periodic pattern sensing elements due to the periodic pattern.