Position encoders first evolved in response to the needs of generally low-speed or static measurements. Demands for increasingly accurate metrology were met by high quality optical scales, with ever-finer digital interpolation achieved by progressive improvements in electronics. The commercial encoder systems that emerged to satisfy these requirements relied on optical fringe generation and a means of electrical detection, followed by analogue and digital circuits. These produced subdivided digital signals feeding counters and displays to report position or, more, latterly, encoding an absolute position directly.
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