Sheet feeding assembly including automatic stack replacement and aligning means

Claim 2

In a sheet feeding apparatus having a tray supporting a first stack of sheets and a feeding mechanism for removing sheets from the stack on the tray and feeding the sheets out of the apparatus one at a time, the improvement comprising: elevating means for continuously raising the tray from a bottom position as the feeding mechanism feeds out the sheets so that the successive top sheets of the first stack are maintained substantially at a predetermined height and for lowering the tray to the bottom position when the last sheet has been fed out; sensing means disposed at the tray for sensing when the last sheet of the first stack has been fed out by the feeding mechanism and for generating a signal indicative thereof; conveyor means arranged adjacent to the tray for supporting a second stack of sheets, and being responsive to said signal to move the second stack of sheets to the tray to be fed out; and alignment means for urging and aligning side edges and rearward edges of the stack of sheets on the tray, and being responsive to said signal to clear the path of movement of the second stack of sheets while they are being moved to the tray.

Claim 3

In a sheet feeding apparatus having a tray supporting a first stack of sheets and a feeding mechanism for removing sheets from the stack on the tray and feeding the sheets out of the apparatus one at a time, the improvement comprising: elevating means for continuously raising the tray from a bottom position as the feeding mechanism feeds out the sheets so that the successive top sheets of the first stack are maintained substantially at a predetermined height and for lowering the tray to the bottom position when the last sheet has been fed out; sensing means disposed at the tray for sensing when the last sheet of the first stack has been fed out by the feeding mechanism and for generating a signal indicative thereof; conveyor means arranged adjacent to the tray for supporting a second stack of sheets, and being responsive to said signal to move the second stack of sheets to the tray to be fed out; and alignment means for urging and aligning side edges and rearward edges of the stack of sheets on the tray, and being responsive to said signal to clear the path of movement of the second stack of sheets while they are being moved to the tray.

Claim 4

In a sheet feeding apparatus having a tray supporting a first stack of sheets and a feeding mechanism for removing sheets from the stack on the tray and feeding the sheets out of the apparatus one at a time, the improvement comprising: elevating means for continuously raising the tray from a bottom position as the feeding mechanism feeds out the sheets so that the successive top sheets of the first stack are maintained substantially at a predetermined height and for lowering the tray to the bottom position when the last sheet has been fed out; sensing means disposed at the tray for sensing when the last sheet of the first stack has been fed out by the feeding mechanism and for generating a signal indicative thereof; conveyor means arranged adjacent to the tray for supporting a second stack of sheets, and being responsive to said signal to move the second stack of sheets to the tray to be fed out; and alignment means for urging and aligning side edges and rearward edges of the stack of sheets on the tray, and being responsive to said signal to clear the path of movement of the second stack of sheets while they are being moved to the tray.

Claim 5

The apparatus according to claim 1, in which said alignment means comprises: a vertically disposed fixed plate arranged outward of and parallel to one side of said conveyor means; a generally vertically disposed tilting plate arranged outward of and parallel to the other side of said conveyor means, said tilting plate being tiltably mounted at its bottom edge; biasing means for urging said tilting plate to tilt inward toward said conveyor means to urge and align the sheets against said fixed plate; solenoid controlled arm means for normally urging the sheets toward the tray and disengaging them from said tilting plate; and a pressure switch disposed at the tray and sensitive to the weight of the sheets on the tray, said pressure switch being arranged to actuate said arm means when the last sheet of the first stack has been fed out and the weight of the sheets on said pressure switch is thereby zero to move said arm means to a position so that the second stack of sheets will clear said arm means while being fed to the tray and said arm will engage with said tilting plate to tilt said tilting plate outwardly away from said conveyor means against the force of said biasing means to prevent said tilting plate from impeding the movement of the second stack of sheets to the tray, said pressure switch de-actuating said arm means when the second stack of sheets contacts the tray due to the weight of the sheets.

Claim 6

The apparatus according to claim 2, in which said arm means comprises: a rotary shaft arranged above and transverse to said conveyor means; arms fixed to said rotary shaft arranged to normally engage with the edges of the sheets to urge the sheets toward the tray; an actuAting arm fixed to said rotary shaft arranged to normally disengage from said tilting plate; and a rotary solenoid arranged to normally rotate said rotary shaft so that said arms engage with the sheets and said actuating arm disengages from said tilting plate and to be actuated by said pressure switch to rotate said rotary shaft so that said arms are moved to a position of disengagement from the sheets and said actuating arm engages with said tilting plate to tilt said tilting plate outward away from said conveyor means.

Claim 7

The combination according to claim 3, in which said arms are hollow, and communicate with a source of pressurized air through a passageway formed through said rotary shaft, said arms being further formed with orifices facing the sheets when in engagement therewith so that pressurised air is blown against the rear edges of the sheets to prevent adhesion of the sheets.

Claim 8

The combination according to claim 1, in which said conveyor means comprises a pair of motor driven endless conveyor belts straddling the tray and supporting the second stack of sheets, said sensing means being connected to the motor to control the same and the upper surfaces of said conveyor belts being at approximately the same height as the tray when the tray is in the bottom position.

Claim 9

The combination according to claim 1, in which said conveyor means comprises: a motor driven bed movable to and away from the tray; a horizontally disposed frame supporting the second stack of sheets; a pair of parallel links pivotally connected to said bed and said frame to support said frame, said links being pivotal in a vertical plane parallel to the direction of movement of said bed; and fixed actuating pins engagable with one of said links near the ends of travel of said bed; the motor of said motor driven bed being controlled by said sensing means; whereby said bed is normally at its end of travel farthest from the tray with said one of said links engaged with one of said actuating pins to rotate said link to a position to move said frame to a height above the tray when the tray is in the bottom position; the motor of said motor driven bed is actuated by the signal from said sensing means to move said bed toward the tray; said one of said links disengages from said one of said actuating pins and engages with another of said actuating pins to rotate to a position to move said frame to straddle the tray at a height below the tray and thereby place the second stack of sheets on the tray; and the motor of said bed is actuated by the absence of the signal from said sensing means as the tray is raised by said elevating means to move said bed away from the tray so that said one of said links disengages from said another of said actuating pins and again engages with said one of said actuating pins to move said frame to the height above the tray when the tray is in the bottom position.

Claim 10

A sheet feeding apparatus comprising, in combination: a horizontally disposed, vertically movable tray adapted to support a first stack of sheets; a pick-up lever pivotal about a fixed point; suction members carried by the pick-up lever engagable with the top sheet of the first stack; feed-out means for taking sheets from the suction members and feeding the sheets out of the apparatus; a vertically disposed rack fixed to the tray; a pinion shaft carrying a pinion engaging with the rack; a ratchet fixed to the pinion shaft parallel to the pinion; a drive pawl and a holding pawl operatively engaging with the ratchet; a pawl lever fixed to the pinion shaft and carrying the drive pawl; cams rotated by a prime mover; first and second linkages connecting the cams to the pick-up lever and the pawl lever respectively so that the pick-up lever is urged to rock and cause the suction members to pick up the sheets from the first stack one sheet at a time and pass the sheets to the feed-out means, and the pawl lever is also Urged to rock and urge the pawl to rotate the ratchet and thereby the pinion to cause the rack and the tray to move upward to maintain the top of the first stack at substantially a predetermined height as the sheets are being fed out; release means for normally urging the pawl lever and the second linkage to disengage from the cams, the release means being de-actuated by the pick-up lever when the height of the top of the first stack drops below the predetermined height; a release solenoid arranged to disengage the drive and holding pawls from the ratchet when actuated; a pressure switch provided to the tray arranged to actuate the release solenoid when the last sheet of the first stack is lifted off the tray by the suction members whereby the tray drops down to a bottom position; conveyor means supporting a second stack of sheets and adapted to straddle the tray; sensing means arranged to be actuated by the tray when the tray reaches the bottom position to generate a signal to actuate the conveyor means to move the second stack to the tray; and alignment means for aligning the stack of sheets on the tray, said alignment means being responsive to said signal to clear the path of movement of the second stack of sheets while being moved to the tray.

Claim 11

A sheet feeding apparatus comprising, in combination: a horizontally disposed, vertically movable tray adapted to support a first stack of sheets; a pick-up lever pivotal about a fixed point; suction members carried by the pick-up lever engagable with the top sheet of the first stack; feed-out means for taking sheets from the suction members and feeding the sheets out of the apparatus; a vertically disposed rack fixed to the tray; a pinion shaft carrying a pinion engaging with the rack; a ratchet fixed to the pinion shaft parallel to the pinion; a drive pawl and a holding pawl operatively engaging with the ratchet; a pawl lever fixed to the pinion shaft and carrying the drive pawl; cams rotated by a prime mover; first and second linkages connecting the cams to the pick-up lever and the pawl lever respectively so that the pick-up lever is urged to rock and cause the suction members to pick up the sheets from the first stack one sheet at a time and pass the sheets to the feed-out means, and the pawl lever is also Urged to rock and urge the pawl to rotate the ratchet and thereby the pinion to cause the rack and the tray to move upward to maintain the top of the first stack at substantially a predetermined height as the sheets are being fed out; release means for normally urging the pawl lever and the second linkage to disengage from the cams, the release means being de-actuated by the pick-up lever when the height of the top of the first stack drops below the predetermined height; a release solenoid arranged to disengage the drive and holding pawls from the ratchet when actuated; a pressure switch provided to the tray arranged to actuate the release solenoid when the last sheet of the first stack is lifted off the tray by the suction members whereby the tray drops down to a bottom position; conveyor means supporting a second stack of sheets and adapted to straddle the tray; sensing means arranged to be actuated by the tray when the tray reaches the bottom position to generate a signal to actuate the conveyor means to move the second stack to the tray; and alignment means for aligning the stack of sheets on the tray, said alignment means being responsive to said signal to clear the path of movement of the second stack of sheets while being moved to the tray.

Claim 12

A sheet feeding apparatus according to claim 7, further comprising holding means actuated by said release solenoid for maintaining the suction members in an upper position while the second stack is being moved to the tray.

Claim 13

A sheet feeding apparatus according to claim 7, in which said alignment means comprises: a vertically disposed fixed plate arranged outward of and parallel to one side of said conveyor means; a generally vertically disposed tilting plate arranged outward of and parallel to the other side of said conveyor means, said tilting plate being tiltably mounted at its bottom edge; biasing means for urging said tilting plate to tilt inward toward said conveyor means to urge and align the sheets against said fixed plate; solenoid controlled arm means for normally urging the sheets toward the tray and for disengaging them from said tilting plate; and a conveyor pressure switch disposed at the tray and sensitive to the weight of the sheets on the tray, said conveyor pressure switch being arranged to actuate said arm means when the last sheet of the first stack has been fed out and the weight of the sheets on said conveyor pressure switch is thereby zero to move said arm means to a position so that the second stack of sheets will clear said arm means while being fed to the tray and said arm will engage with said tilting plate to tilt said tilting plate outwardly away from said conveyor means against the force of said biasing means to prevent said tilting plate from impeding the movement of the second stack of sheets to the tray, said conveyor pressure switch de-actuating said arm means when the second stack of sheets contacts the tray due to the weight of the sheets.

Claim 14

A sheet feeding apparatus according to claim 9, in which said arm means comprises: a rotary shaft arranged above and transverse to said conveyor means; arms fixed to said rotary shaft arranged to normally engage with the edges of the sheets to urge the sheets toward the tray; an actuating arm fixed to said rotary shaft arranged to normally disengage from said tilting plate; and a rotary solenoid arranged to normally rotate said rotary shaft so that said arms engage with the sheets and said actuating arm disengages from said tilting plate and to be actuated by said conveyor pressure switch to rotate said rotary shaft so that said arms are moved to a position of disengagement from the sheets and said actuating arm engages with said tilting plate to tilt said tilting plate outward away from said conveyor means.

Claim 15

A sheet feeding apparatus according to claim 10, in which said arms are hollow, and communicate with a source of pressurized air through a passageway formed through sAid rotary shaft, said arms being further formed with orifices facing the sheets when in engagement therewith so that pressurized air is blown against the rear edges of the sheets to prevent adhesion of the sheets.

Claim 16

A sheet feeding apparatus according to claim 7, in which said conveyor means comprises a pair of motor driven endless conveyor belts stradding the tray and supporting the second stack of sheets, said sensing means being connected to the motor to control the same and the upper surfaces of said conveyor belts being at approximately the same height as the tray when the tray is in the bottom position.