Patent ID: 7162383
Filing Date: 2007-01-09
Classification: G01B

Abstract:
1. A calibration method for a surface texture measuring instrument that measures a surface of a workpiece, the instrument including: an arm supported to be swingable around a base point; a stylus that is arranged on an end of the arm and is provided with a contact point on a tip thereof; the contact point being in contact or nearly in contact with the workpiece along a substantial tangent line of an arc drawn by a tip of the contact point in accordance with a swing of the arm; a shifter for shifting the arm in x-direction while keeping the contact point in contact or nearly in contact with the workpiece surface; a first detector for detecting a displacement of the base point in the x-direction; a second detector for detecting a displacement in z-direction due to the swing of the arm based on a displacement of a point on the arm in the z-direction; and a compensation computing unit that compensates detection results of the first detector and the second detector for a deviation due to the swing to obtain measurement data of the workpiece surface, the calibration method comprising: a measurement step for measuring a calibration gauge of which cross section contains a part of a substantially perfect circle; an assignment step for assigning the detection results of the first detector and the second detector, which are obtained in the measurement step, in an evaluation formula based on a circle equation in which the center coordinates of the calibration gauge are (x a calibration step for calibrating gain of z-coordinate of the tip of the contact point relative to the detection result of the second detector and each parameter included in the deviation based on the results obtained in the assignment step; and a storage step for storing the calibrated gain and each calibrated parameter.