Patent ID: 7221178

Claim:
A working system for circuit boards comprising: reference mark position detection means for detecting the position of a reference mark provided on a circuit board; working means for performing predetermined works on the circuit board on the basis of the position of the reference mark detected by the reference mark position detection means; circuit board transfer means for transferring the circuit board to a working position where the predetermined works are to be performed by the working means; a peculiar portion provided at a position lower than the circuit board on the circuit board transfer means such that the peculiar portion is detectable by the reference mark position detection means when the circuit board is not between the peculiar portion and the reference mark position detection means, and the peculiar portion is not detectable by the reference mark position detection means when the circuit board arrives at a predetermined position on the circuit board transfer means during the transfer operation of the circuit board; and judgment means responsive to a signal from the reference mark position detection means for detecting whether the circuit board is absent or present at the predetermined position on the circuit board transfer means.