| 摘要 |
PURPOSE:To obtain an output pulse signal with invariably constant width and to improve the SN ratio by providing an origin mark at two positions at an interval (d) and setting intervals of four magnetoelectric converting and detecting elements which constitute an origin mark read head to d/2. CONSTITUTION:The origin mark detection head 7 is fixed and when a magnetic scale 1 rotates counterclockwise by 3d, its output signal has waveforms P1-P6 having six peak values in total. When the crest value of the P1 is V0, P2, P5, and P6 are + or -V0 and the P3 and P4 are + or -2V0. Further, the level of a noise is a level where only one of the respective magneto-resistance elements 8-11 of the magnetic detection head 7 senses magnetism, i.e. at most about V0. For the purpose, when the P3 or P4 is regarded as an origin detection signal, a noise margin of a difference 2V0-V0 between the P3 or P4 and P1, i.e. V0 is obtained securely. Further, the interval between the output waveforms P3 and P4 becomes d/2 and respective peak intervals are all d/2 and become difficult to be affected by magnetism or the accuracy of the manufacture of the head. |
