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GMR Multistack sensor for high resolution encoder application used for incremental and / or absolute applications.

IP.com Disclosure Number: IPCOM000030411D
Original Publication Date: 2004-Aug-12
Included in the Prior Art Database: 2004-Aug-12

Publishing Venue

IBM

Abstract

Disclosed is a device that uses a new concept to decode the position of a magnetic encoder disc using one single track. The concept is based on a digital signal and signal treating and supports absolute encoding without signal interpolation. Because the resolution is dependent to the sensor stack geometric large magnetic pattern can be used on the encoder side with high magnetic flux. This has the advantage that a relative large distance between encoder plane and sensor stack can be realized. Starting from the vernier concept, what uses an array of sensors to improve the resolution this new concept uses a multistack sensor device. The stack height must be larger than the longest bit on the encoder plane. Then the output of each single sensor can be analyzed and the incremental resolution is improved, the index for the incremental decoding can be embedded into the signal track, absolute decoding can be done in parallel to the incremental decoding and the rotation speed and moving direction can be detected.