Patent ID: 7347419

Claim:
A sheet supplying device comprising: a stacker for placing sheets, a delivery device for separating the sheets on the stacker and feeding the sheets, a register device for temporarily holding a sheet from the delivery device, a sheet conveying guide for guiding the sheet from the register device to a processing position, a sheet sensor disposed between the delivery device and the register device for detecting the sheet, at least one driving device for driving the delivery device and the register device, a conveyance control device for controlling the driving device so that the delivery device and the register device form a loop in the sheet according to a signal from the sheet sensor when a leading edge thereof reaches the register device, an overlap sensor disposed between the register device and the processing position for detecting overlapping of the sheets, and an overlap determining device for determining the overlapping of the sheet according to signals from the sheet sensor and the overlap sensor, said overlap determining device obtaining an overlapping signal of the sheet at a position where the loop in the sheet is eliminated by the register device, and determining the overlapping signal as an effective signal when the overlapping signal is obtained within a predetermined time since the sheet sensor detects a rear edge of the sheet.