Patent ID: 7948516

Claim:
A method for evaluating position accuracy by running a computer program on a computer indicating, when members made of a second material are arranged within a disk-shaped first material so as to form a first circle of the second material having a radius of a first length and a second circle of the second material having a radius of a second length, deviation amounts of the first circle and the second circle from designed positions, comprising steps of: substantially equally dividing an outer circumference of the disk-shaped first material into n and measuring a first position to an n-th position; measuring an (n+1)th position, which is an intersection of a first radius and a circular arc of the first circle, the first radius connecting the center of the disk-shaped first material and the first position, to a 2n-th position, which is an intersection of an n-th radius and the circular arc of the first circle, the n-th radius connecting the center of the disk-shaped first material and the n-th position; measuring a (2n+1)th position, which is an intersection of the first radius and a circular arc of the second circle, to a 3n-th position, which is an intersection of the n-th radius and the circular arc of the second circle; calculating a first vector starting from the (n+1)th position and ending at the first position to an n-th vector starting from the 2n-th position and ending at the n-th position; calculating an (n+1)th vector starting from the (2n+1)th position and ending at the (n+1)th position to a 2n-th vector starting from the 3n-th position and ending at the 2n-th position; calculating a first combined vector by adding the first to the n-th vectors; calculating a second combined vector by adding the (n+1)th to the 2n-th vectors; and evaluating the position accuracy of the first and the second circles with respect to the outer circumference of the disk-shaped first material, based on a third combined vector obtained by adding the first combined vector and the second combined vector, wherein n is a natural number of at least four.