Sheet material feeding mechanism

A sheet material feeding mechanism of an image processing apparatus for feeding a sheet material from a stack of sheet materials mounted on a hopper or a tray to an image processing system, the sheet feeding mechanism comprising:

• an overlap feeding detection mechanism and a pair of guide plates disposed on upper and lower sides of a sheet material feeding line, the overlap feeding detection mechanism including (a) an ultrasonic transmitting device for transmitting an ultrasonic wave toward a sheet material on the sheet material feeding line, and (b) an ultrasonic receiving device opposite to the ultrasonic transmitting device across the sheet material feeding line for receiving the ultrasonic wave which has passed through the sheet material and been attenuated thereby;
• and
• at least one pair of bending correction ribs provided on each guide plate, the ribs on each guide plate being opposite to each other across the ultrasonic transmitting passageway between the ultrasonic transmitting device and the ultrasonic receiving device, and being operable to urge the sheet material on the sheet material feeding line to deflect upward or downward in at least an area including the ultrasonic transmitting passageway so as to form a gap between the sheet materials being fed in a closely overlapped condition, wherein:
• an output value of the attenuated ultrasonic wave is compared with a predetermined reference value to detect an overlap feeding of sheet materials, and
• the bending correction ribs disposed on the upper guide plate are disposed so that a distance therebetween gradually closes toward a sheet material feeding direction.

A sheet material feeding mechanism of an image processing apparatus for feeding a sheet material from a stack of sheet materials mounted on a hopper or a tray to an image processing system, the sheet feeding mechanism comprising:

• an overlap feeding detection mechanism and a pair of guide plates disposed on upper and lower sides of a sheet material feeding line, the overlap feeding detection mechanism including (a) an ultrasonic transmitting device for transmitting an ultrasonic wave toward a sheet material on the sheet material feeding line, and (b) an ultrasonic receiving device opposite to the ultrasonic transmitting device across the sheet material feeding line for receiving the ultrasonic wave which has passed through the sheet material and been attenuated thereby;
• and
• at least one pair of bending correction ribs provided on each guide plate, the ribs on each guide plate being opposite to each other across the ultrasonic transmitting passageway between the ultrasonic transmitting device and the ultrasonic receiving device, and being operable to urge the sheet material on the sheet material feeding line to deflect upward or downward in at least an area including the ultrasonic transmitting passageway so as to form a gap between the sheet materials being fed in a closely overlapped condition, wherein:
• an output value of the attenuated ultrasonic wave is compared with a predetermined reference value to detect an overlap feeding of sheet materials, and
• a friction coefficient between the bending correction ribs disposed on the lower guide plate and the sheet material is larger than a friction coefficient between the bending correction ribs disposed on the upper guide plate and the sheet material.