| 摘要 |
PURPOSE:To adjust a sinusoidal wave output without fluctuation by providing a detection unit for compensation in addition to a detection unit of speed detection and feeding back negatively the output of the detection unit for compensation to both the detection units. CONSTITUTION:A recording medium 29 is moved as shown in the arrow, moved synchronously with the speed detection object and the recording medium 29 has the 1st magnetic recording section 30 and the 2nd magnetic recording section 31. The 1st magnetic recording section 30 has magnetic domain where N, S are magnetized alternately in a direction perpendicular to the moving direction and the 2nd magnetic recording section 31 has the magnetic domain where N, S poles are magnetized while being sectioned in the moving direction. Four magnetoresistance effect elements 14-17 constituting the detection unit 12 at the position near the surface of the 1st magnetic recording section 30 are provided and the detection unit 12 is fixed. The four elements 14-17 are connected to form a bridge constitution to impress the DC power supply 10. The detection unit 13 is constituted similarly as the detection unit 12 and the output of the compensation detection unit 13 is fed back negatively.
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