| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a measuring instrument that automatically corrects a measured value by discriminating a change of receiving light quantity caused by approach of a work-piece and a change of receiving light quantity caused by influence of adhesion of dust or the like. <P>SOLUTION: The measuring instrument is composed of a reference receiving light quantity storage unit 32 for retaining a reference receiving light quantity A that shows a receiving light quantity when a work-piece W does not enter a measuring area 2, a measurement value calculation unit 33 for calculating a measurement value y showing an advancement amount of the work-piece W into the measuring area 2 based on a ratio of the reference receiving light quantity A and a receiving light quantity X, a reference receiving light quantity correction unit 38 for correcting the reference receiving light quantity A so that the ratio of the reference receiving light quantity A and the receiving light quantity X becomes closer to a predetermined value, and a change rate calculation unit 35 for obtaining a change rate of the receiving light quantity X corresponding to an advancing speed V of the work-piece W into the measuring area 2. The reference receiving light quantity correction unit 38 corrects the reference receiving light quantity A when the change rate is smaller than a predetermined threshold Th1 and the receiving light quantity X is larger than a threshold Th2 determined based on the reference receiving light quantity A. <P>COPYRIGHT: (C)2012,JPO&INPIT |
