| 摘要 |
PURPOSE:To improve resolution by arranging plural magneto-resistance elements so that they are magnetized in turn when a magnetic mark detecting circuit is moved relatively with a magnetic scale, and deciding on its detection output and calculating the position of a magnetic head. CONSTITUTION:A composite bridge circuit 4 consists of magneto-resistance elements 10-19 and reference resistance element 9 and 9'. A position deciding circuit 5 consists of comparing circuits 20-29, AND gates 30-39, FFs 40-49, and a driving circuit 50 for an up/down counter 8. Magnetic marks 2 and 2' are formed by magnetizing the surface of a medium forming the magnetic scale 1 vertically and alternately in the opposite directions at desired pitch lambda. The circuit 4 is fixed and the scale 1 is moved to right and left. When the scale 1 is moved to right by up to 1/10 as large as lambda, three of elements 10-19 are positioned on the marks 2 and 2' invariably in turn. The circuits 20-29 compare the output of the circuit 4 with a reference voltage and outputs the result to display the position of the scale 1 on a position display device 6 accurately. Thus, the resolution is improved.
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