Patent ID: 7657997

Claim:
A reference position determining method for determining a reference position of a circuit board in execution of a process related to mounting of electronic components onto the circuit board, wherein the circuit board is a flexible circuit board or a circuit board held on a conveyor member in execution of the process, said method comprising: acquiring respective positional data of at least three reference-position-determining marks which are provided on at least one circuit board to be integrally treated in the process; determining relative positional relations between the at least three marks and comparing each of the relative positional relations with a corresponding predetermined reference positional relation to determine whether each of the relative positional relations is within a first permissible range; specifying one of the at least three marks as a displaced mark when the relative positional relation of the one mark is outside a second permissible range and each of the relative positional relations is within the first permissible range; determining the reference position for the at least one circuit board using positional data that excludes positional data of the displaced mark; and positioning the at least one circuit board based on the reference position after the reference position of the at least one circuit board has been determined, wherein said determining relative positional relations comprises determining lengths of line segments interconnecting the at least three marks as the relative positional relations for the at least three marks, and the lengths of the individual line segments are compared with predetermined threshold values of length corresponding to the line segments.