Sheet feed mechanism having plural independent feed rollers and plural sensor arrangement

A sheet feed mechanism comprising:

• a first feed roller mounted on a feed path of sheets including mail pieces and rotated by a first one-way clutch in only a feed direction, said first feed roller having a high-friction member on an outer circumference thereof;
• a second feed roller arranged on an upstream side of said first feed roller in the feed direction to be pivotal about said first feed roller as a center and rotated by a second one-way clutch in only the feed direction, said second feed roller having a high-friction member on an outer circumference thereof and pressing against a sheet stacked on a feed table in an upright state to feed out the sheet in the feed direction;
• a first servo motor for driving said first and second feed rollers;
• a reverse roller pressed against by said first feed roller through said feed path and driven to rotate in a counter feed direction, said reverse roller being rotatable both in the feed direction and the counter feed direction;
• a torque limiter for constantly applying a predetermined driving torque to said reverse roller in the counter feed direction;
• a pick-up roller arranged on a downstream side of said first feed roller in the feed direction and constantly rotated to feed the sheet to a downstream transport path;
• a third feed roller arranged on said upstream side of said second feed roller in the feed direction and rotated by a one-way clutch in only the feed direction, said third feed roller having a high-friction member on an outer circumference thereof and pressing against the sheet stacked on said feed table in the upright state;
• a second servo motor for driving said third feed roller independently;
• and
• a plurality of photoelectric sensors sequentially arranged on said feed path between said first feed roller and said pick-up roller.