| 摘要 |
PROBLEM TO BE SOLVED: To enhance reception sensitivity to make a detection distance easily lengthened when a detection sensor is constituted using two coils. SOLUTION: In this sensor, the first coil (transmission coil) serving as a magnetic flux generating source, and the second coil (reception coil) for generating an inducted output by an influence of a magnetic flux therein are arranged opposedly with a prescribed space, the presence of a metal sheet between both coils is detected by a level of the induced output in the second coil (reception coil). In the sensor, an intermittent drive means for driving intermittently excitation of the first coil (transmission coil) is provided, and a constant current source (constant current power source) is used as an electric energy supply source for driving intermittently the first coil (transmission coil) in the intermittent drive means. |
