PROXIMITY SENSOR

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PROBLEM TO BE SOLVED : To provide a precise proximity sensor free from the influence due to unevenness of magnets. SOLUTION : When a magnet 10 as a rare earth bond magnet is injection-molded, a first yoke is inserted between the N/S magnetic pole surfaces so that a protruding portion 22 of the first yoke protrudes from a wall perpendicular to a magnetic pole surface 12. A protrusion 32 of a second yoke 30 is disposed in parallel to the wall face of the magnet 10 with a main body 31 being faced to the protruding portion 22. In a space between the protruding portion 22 and the protrusion 32, a hall IC 40 is disposed with the magnetic sensitive direction in a direction connecting the protruding portion and the protrusion. When an object 50 to be detected is away from the magnetic pole surface 12, the magnetic flux crosses the magnetic sensitive direction. When an object 50 to be detected comes closer to the magnetic pole surface 12, the magnetic flux flows between the protrusion 32 and the protruding portion 22 in the magnetic sensitive direction, and the hall IC 40 detects the changes of the density of the magnetic flux with a high sensitivity. Since only one single magnet 10 is provided, the proximity sensor is free from the influence due to unevenness among plural magnets and/or mounting unevenness. COPYRIGHT : (C)2013, JPO&INPIT