Gsi Group Corporation

Keith M Hinrichs

William G Thorburn

Alva E Hare

Andrew M Goldman

Donald K Mitchell

Joel Mikael Petersen

Christopher Chapman Rich

Donald L Grimes

Kurt Sidor

Stuart A Dodson, Ii

A rotary optical position encoder for detecting angular position includes a light source, a monolithic scale disk including an optical scale pattern, a monolithic reticle substrate including sets of reticle aperture patterns between the light source and the scale disk, detection and conversion circuitry, and digital processing circuitry. The light source, scale disk, reticle substrate, and detection and conversion circuitry form a plurality of optical sub-encoders at angular positions about the rotational axis, each sub-encoder having an optical path extending from the light source to the detection and conversion circuitry via a respective set of reticle aperture patterns and the optical scale pattern. The digital processing circuitry is operative to combine digital position output values of the sub-encoders to generate an encoder position output value. The optical sub-encoders can include incremental position encoders that provide high-resolution position indications with improved thermally stability due to the use of a shared reticle substrate. Additional optical sub-encoders provide zero-reference or 'index' indications as well as a coarse absolute position.

Rotary optical encoder employing multiple subencoders with common reticle substrate

An absolute encoder employs multiple sub-encoders of different resolutions and a linking algorithm for combining the sub-encoder outputs to form an accurate, high-resolution position estimate. The sub-encoders can utilize edge modulation of a main grating track, sloped patterns of successively higher periods, and other types of scale patterns. The sub-encoders can also use a variety of detector types suitable for the patterns being used. In one linking approach, pairs of tracks are linked together successively by applying a phase shift to the coarser track and then combining it with the finer track such that the transitions of the coarse track estimates become aligned with those of the finer track, whereupon the values can be combined to form a linked position estimate. In another approach, beat tracks are calculated from physical tracks of similar period, and the beat tracks are used as the coarser tracks in the linking process.

Absolute encoder employing linked sub-encoders and beat track

A flexible optical marker is applied to an optical scale substrate to make an optical scale assembly for an optical position encoder. The marker may be a limit marker, index marker, or other type of marker. The marker substrate may be a plastic film such as polyester, singulated from a 'recombine' roll created by a web process. The marker has a microstructured pattern on one surface that is covered with a reflective metal coating. The marker also has an adhesive layer and is affixed to the optical scale substrate by a process of aligning the marker to an edge of the scale and then applying pressure to the upper surface of the marker. The marker may be applied with a handle portion that is separated from the marker after the marker is affixed. The marker may be especially useful with a flexible scale substrate such as a metal tape substrate. By affixing the marker to the scale substrate as a separate step of making an encoder scale, various benefits such as reduced inventory, cost, and lead time may be achieved.

Scale assembly for optical encoder having affixed optical reference markers

An absolute encoder employs multiple sub-encoders of different resolutions and a linking algorithm for combining the sub-encoder outputs to form an accurate, high-resolution position estimate. The sub-encoders can utilize edge modulation of a main grating track, sloped patterns of successively higher periods, and other types of scale patterns. The sub-encoders can also use a variety of detector types suitable for the patterns being used. In one linking approach, pairs of tracks are linked together successively by applying a phase shift to the coarser track and then combining it with the finer track such that the transitions of the coarse track estimates become aligned with those of the finer track, whereupon the values can be combined to form a linked position estimate. In another approach, beat tracks are calculated from physical tracks of similar period, and the beat tracks are used as the coarser tracks in the linking process. A wafer-handling robot employs the absolute encoder for controlling rotation of multiple joints.

Precision material-handling robot employing high-resolution, compact absolute encoder

Absolute encoder employing concatenated, multi-bit, interpolated sub-encoders

An optical encoder includes an optical source, a scale, an optical detector and signal processing circuitry. The scale is operative with a light beam from the source to generate an optical pattern such as a line pattern extending in an X direction of relative movement between the scale and the source. The detector generates analog detector output signals indicative of the location of the optical pattern on the detector in an alignment direction orthogonal to the X direction. The detector may include two bi-cell elements spaced apart in the X direction, each element including two cells of complementary shape, such as a sharks-tooth. The signal processing circuitry operates in response to the detector output signals to generate an alignment value indicating a polarity and a magnitude of misalignment between the detector and the scale in the alignment direction. A method of providing information to a user regarding alignment of a detector and an encoder scale employs a graphical alignment indicator displayed on a computer display. The graphical alignment indicator has a bipolar indicator scale and a marker whose location on the scale is based on the alignment values such that the magnitude and polarity of misalignment is indicated.

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Natick, MA, United States of America

Keith M Hinrichs