Patent ID: 7280211

Claim:
A method of adjusting a monitoring apparatus, said monitoring apparatus being adapted to carry out a measurement operation by receiving waves from a detection area at each position on a standard direction and outputting data for identifying at least position of a target object of detection in said detection area based at least on intensity of said received waves, said method serving to correct an axial displacement of said detection area in the direction of rolling; said method comprising the steps of: providing a target having a detection surface, said detection surface having a specified peripheral shape and having a pattern of bright areas with a larger reflectivity and dark areas with a smaller reflectivity, said peripheral shape and said pattern being such that a waveform of W-form or inverse W-form is obtained due at least to said specified pattern if said measurement operation is carried out with said target placed in front of said monitoring apparatus and with said detecting area facing said detection surface, said waveform being such that a standard position of said detection surface in said standard direction can be calculated therefrom; placing said target in front of said monitoring apparatus by orienting said detection surface according to said standard direction; carrying out said measurement operation at least twice by each time changing the position of said monitoring apparatus in the perpendicular direction to said standard direction; and determining the axial deviation of said detection area in the rolling direction based on change in said standard position calculated from said waveform; wherein said detection surface of said target has outer edges which are perpendicular to said standard direction and has a width in said standard direction, said width being smaller than the dimension of said detection area in said standard direction; wherein said pattern includes an elongated belt-like region traversing a center part of said detection surface and inversion areas on both sides of said belt-like region, either said belt-like region or said inversion areas having higher reflectivity than the other; and wherein said standard position is determined from position data a and b of points on opposite sides of the center valley or hill of said waveform of W-form or inverse W-form having the same received wave intensity as at said center valley or hill.