Sheet feeder having improved sheet separation regardless of rigidity and size of sheet

A sheet feeder for feeding each one of cut sheets in a sheet feeding direction comprising:

• a hopper housing therein a stack of sheets and having a wall portion at a position in confrontation with each leading edge of the sheets when the stack of sheets are housed in the hopper, the wall portion comprising a sheet receiving surface in contact with each leading edge of the sheets, and a slanted surface positioned downstream of the sheet receiving surface in the sheet feeding direction;
• first and second sheet feed rollers disposed in contact with an uppermost sheet of the sheet stack for feeding the uppermost sheet in the sheet feeding direction;
• a stop member movable between a protruding position protruding out of the slanted surface and a retracted position retracting into the slanted surface;
• and
• a biasing member connected to the stop member for urging the stop member to its protruding position, the first sheet feed roller providing a first sheet feed force directing in the sheet feeding direction, and a second sheet feed roller providing a second sheet feed force directing in the sheet feeding direction, the first and second sheet feed forces providing a resultant force directing in the sheet feeding direction along a resultant force line and at a line of action which is along the resultant force line, the stop member being positioned symmetrically with respect to the line of action in the widthwise direction of the sheet.

A sheet feeder for feeding each one of cut sheets in a sheet feeding direction comprising:

• a hopper housing therein a stack of sheets, the hopper having a wall portion at a position in confrontation with each leading edge of the sheets when the stack of sheets are housed in the hopper;
• at least one sheet feed roller disposed in contact with an uppermost sheet of the sheet stack for feeding the uppermost sheet in the sheet feeding direction;
• the wall portion comprising a sheet receiving surface in contact with each leading edge of the sheets, and a slanted surface positioned downstream of the sheet receiving surface in the sheet feeding direction;
• a stop member movable between a protruding position protruding out of the slanted surface and a retracted position retracting into the slanted surface, the stop member having a contact surface in contact with the sheet, a maximum angle defined between the contacting surface and the sheet in the hopper being 90 degrees when the stop member is in the protruding position, the contact surface being formed with a groove extending in a widthwise direction of the sheet;
• and
• a biasing member connected to the stop member for urging the stop member to the protruding position.

A sheet feeder for feeding each one of cut sheets in a sheet feeding direction comprising:

• a hopper housing therein a stack of sheets, the hopper having a wall portion at a position in confrontation with each leading edge of the sheets when the stack of sheets are housed in the hopper;
• at least one sheet feed roller disposed in contact with an uppermost sheet of the sheet stack for feeding the uppermost sheet in the sheet feeding direction;
• the wall portion comprising a sheet receiving surface in contact with each leading edge of the sheets, and a slanted surface positioned downstream of the sheet receiving surface in the sheet feeding direction;
• a stop member movable between a protruding position protruding out of the slanted surface and a retracted position retracting into the slanted surface, the stop member having a contact surface in contact with the sheet, a maximum angle defined between the contacting surface and the sheet in the hopper being 90 degrees when the stop member is in the protruding position, a moving direction of the stop member between the protruding and retracting positions extending in parallel with an orientation of the sheet in the hopper;
• and
• a biasing member connected to the stop member for urging the stop member to the protruding position.

A sheet feeder for feeding each one of cut sheets in a sheet feeding direction comprising:

• a hopper housing therein a stack of sheets, the hopper having a wall portion at a position in confrontation with each leading edge of the sheets when the stack of sheets are housed in the hopper;
• at least one sheet feed roller disposed in contact with an uppermost sheet of the sheet stack for feeding the uppermost sheet in the sheet feeding direction;
• the wall portion comprising a sheet receiving surface in contact with each leading edge of the sheets, and a slanted surface positioned downstream of the sheet receiving surface in the sheet feeding direction, the slanted surface being angled with respect to the sheet receiving surface in a direction toward the sheet feeding direction defined by an orientation of the sheets in the hopper;
• a stop member movable between a protruding position protruding out of the slanted surface and a retracted position retracting into the slanted surface, the stop member having a contact surface in contact with the sheet, a maximum angle defined between the contacting surface and the sheet in the hopper being 90 degrees when the stop member is in the protruding position;
• a biasing member connected to the stop member for urging the stop member to the protruding position;
• a conveyer roller;
• a follower roller in nipping relation to the conveyer roller, the conveyer roller and the follower roller being positioned downstream of the slanted surface in the sheet feeding direction for conveying the sheet fed by the at least one sheet feed roller to an intended location;
• the at least one sheet feed roller further comprising a collar for pressing the uppermost sheet on the hopper, the uppermost sheet bridging between the conveyer roller and the collar under tension to provide a non-slackened state at a position above the slanted surface;
• and
• the stop member being positioned spaced away from the sheet when the stop member is in its protruded position during the non-slackened state of the sheet.