| 摘要 |
PURPOSE:To detect a displaced position with a high precision by forming metallic materials into a film shape on the surface of a plate consisting of nonmagnetic materials at intervals in the movement direction to form a part to be detected, and detecting them with a differential magnetic head. CONSTITUTION:A disc-shaped plate body 5 is stuck to a detecting shaft 1 of a rotary encoder. The plate body 5 consists of nonmagnetic materials, and areas 6 to be detected which consist of metallic materials and have the same shape are formed at equal intervals in the circumferential direction on the surface of the plate body 5. A width WI of areas 6 to be detected in the circumferential direction and a width W2 of intervals are set to the same value. A magnetic head is a differential magnetic head; and with respect to high frequency outputs led out from terminals 13b and 14b, an output difference between coils 13 and 14 is large to obtain a high-level pulse 21 when a detecting part 8a is placed just above areas 6 to be detected. When the detecting part 8a is placed above parts W2 between areas to be detected, a low-level signal 22 is given. The device is so constituted that a signal of about 5 cycles is obtained during a time T of the high-level pulse when the plate body 5 is rotated, thereby detecting the pulse 21 accurately. |
