| CPC F04C 28/28 (2013.01) [F04C 18/16 (2013.01); G01H 9/00 (2013.01); G01P 15/18 (2013.01); F04C 2270/80 (2013.01)] | 9 Claims |

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1. A diagnosis method comprising:
a physical quantity detection step of detecting accelerations along three axes orthogonal to one another by using acceleration sensors, the accelerations being generated due to a vibration of a vacuum pump during operation thereof, the vacuum pump being vibrated around a two-dimensional vibration plane;
a Lissajous figure generation step of generating a three-dimensional Lissajous figure by plotting time-series signals corresponding to the detected accelerations in a three-dimensional coordinate system including a first axis, a second axis, and a third axis as the three axes;
a vibration plane information acquisition step of acquiring information on the two-dimensional vibration plane of the vibration from the three-dimensional Lissajous figure generated in the Lissajous figure generation step; and
a diagnosis step of diagnosing a state of the vacuum pump based on the information of the two-dimensional vibration plane, the information indicating an inclination of the two-dimensional vibration plane with respect to a reference axis.
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