Patent ID: 7557569

Claim:
A state measuring apparatus for a rotary machine, the apparatus comprising: a rotary machine including: a stationary member that does not rotate in a using state; and a rotary member rotatably supported to the stationary member; and a state measuring device including: an encoder provided concentrically to the rotary member or to a member rotating together with the rotary member; a sensor device supported and fixed to the stationary member; and an operator, wherein the encoder is provided with: a detection surface disposed on a circumferential surface of the encoder; and first and second characteristic change portions alternately disposed on the detection surface at equal distances in a circumferential direction, wherein characteristics of the first and second characteristic change portions alternately change in the circumferential direction with equal pitches, and at least one of phases in characteristic change of the first and second characteristic change portions gradually changes in an axial direction with being different from that of the other characteristic change portion, wherein the sensor device includes three or more sensors for changing an output signal in response to change in characteristic of a portion to which the detection portion is opposed, a detection portion of one sensor among them is opposed to the first characteristic change portion, a detection portion of another sensor is opposed to the second characteristic portion, and a detection portion of the other sensor is opposed to a portion that does not overlap with a portion to which the detection portion of the other sensors is opposed in the first and second characteristic change portions, and wherein the operator has a function of calculating displacements or inclinations of the encoder with respect to the stationary member in two or more directions, on the basis of at least two phase differences of phase differences between output signals of the sensors.