| 摘要 |
PROBLEM TO BE SOLVED: To provide a turbo-molecular pump of simple structure capable of easily detecting reverse rotation of a rotor when starting. SOLUTION: This turbo-molecular pump includes a sensor target 46 formed with a step for detecting the number of revolution, and an inductance type rotation sensor 47 provided opposite to a target surface of the sensor target 46. A slit 460 as a sub target for generating a reverse rotation detecting signal in a sensor signal is provided at a position dividing a protrusion part 46a into two protrusion regions (a region at angle ofα1 and a region at an angle ofα2) having a different area from each other. A slit detecting signal corresponding to the slit 460 and a step detecting signal corresponding to a step between the protrusion part 46a and a recessed part 46b are generated in an output signal from the rotation sensor 47. The rotating direction of the rotor can be determined by using the slit detecting signal and the step detecting signal composing the reverse rotation detecting signal. COPYRIGHT: (C)2009,JPO&INPIT
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