| 摘要 |
PROBLEM TO BE SOLVED: To provide a proximity sensor which can improve a user-friendliness. SOLUTION: The proximity sensor 100 is provided with a detecting coil 11 for generating a magnetic field, an exiting circuit 20 for supplying an exiting current of a pulse type to the detecting coil periodically, a detecting circuit 30 which detects an existence of metal and its position based on a voltage generated on both ends of the detecting coil 11 after the supply of the exiting current to the detecting coil is shutdown, and a controlling circuit 40. The controlling circuit 40 controls the exiting circuit 20 so that a supply period of the exiting current can be longer than a supply-shutdown period of the exiting current. As a result, when a material of an detecting object is a non-magnetic metal as represented by aluminum, a variation of a detecting distance due to a thickness of the detecting object can be controlled. Moreover, when the materials of the detecting object are iron and aluminum, the variation of the detecting distance of the proximity sensor can be controlled if the thickness is same. COPYRIGHT: (C)2009,JPO&INPIT
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