ABSOLUTE POSITION DETECTOR

摘要

: A magnetic recording medium is formed on a rotary drum and is divided into a plurality of magnetic tracks. On each tract there is recorded a magnetic signal of a combination of a magnetization portion which consists of two consecutive unit magnets (pitch .lambda.) and a no magnetization portion having the same length (2.lambda.) arranged to alternate over the whole periphery of the track. First magnetoresistive elements in the magnetic sensor are arranged in pairs opposite the magnetic tracks at a distance of .lambda./2. Second magnetoresistive elements opposite the magnetic track that corresponds to the lowest-order bit of the position detecting signals have a number of 2m relative to the first magnetoresistive elements at a distance of ()SML, where SML denotes the length of the magnetic signal of the magnetic track, m denotes the number of increased bits, and n denotes an integer. Detecting signals are thus obtained in a bit number in excess of the number of magnetic tracks and the detector can be made small and light.