Patent ID: 8434758

Claim:
A method for detecting a folded corner of a sheet in a sheet-fed printing press, the sheet-fed printing press including: a left-hand side lay device for registering a left end position of sheets supplied from a feeder to a printing unit, a right-hand side lay device for registering a right end position of sheets supplied from the feeder to the printing unit, and a detector for detecting presence or absence of the sheet at a left end part and a right end part of a front end of the sheet whose position has been registered by one of the side lay devices, the method comprising providing the detector including: a first left-hand end detector supported in the left-hand side lay device, a second left-hand end detector supported in the left-hand side lay device and provided at a position spaced from the first left-hand end detector toward a center in a lateral direction, a first right-hand end detector supported in the right-hand side lay device, and a second right-hand end detector supported in the right-hand side lay device and provided at a position spaced from the first right-hand end detector toward the center in the lateral direction, wherein if the left-hand side lay device is selected among a pair of the side lay devices, the first left-hand end detector supported in the left-hand side lay device and the second right-hand end detector supported in the right-hand side lay device detect the presence or absence of the sheet at the left end part and the right end part of the front end of the sheet, or if the right-hand side lay device is selected, the first right-hand end detector supported in the right-hand side lay device and the second left-hand end detector supported in the left-hand side lay device detect the presence or absence of the sheet at the right end part and the left end part of the front end of the sheet.