US 4,068,839 A · Sheet stacking apparatus

Abstract

A dual exit tray xerographic machine, having a hot roll fuser, supplies its output copy sheets to a large-capacity exit pocket whereat the sheets are stacked in a vertically extending pile, on a servo-movable elevator platform. The platform height is servo controlled so as to maintain the stack's top sheet at a fixed position relative to a fixed-position, generally horizontally extending, sheet discharge path. Sheet stacking is enhanced by a pair of movable bars. A hold-down bar, in its quiescent position, presses the stack's trailing edge portion down to insure reliable insertion of the next sheet. A pusher bar is maintained in an elevated quiescent position during such insertion. After the sheet has been inserted, the pusher bar lowers onto the stack, at a position between the hold-down bar and the stack's leading edge. The pusher bar thus holds the just-inserted sheet down. The hold-down bar synchronously moves in a generally elliptical path, to first clear the trailing edge of the just-inserted sheet. The hold-down bar then moves in an upward path until it again overlies the stack's trailing edge. The hold-down bar now descends onto the stack, as the pusher bar returns to its quiescent position.

Claims15

Dependent claims

Sheet hold-down apparatus for use in stacking flexible sheets in a substantially fixed-position horizontal plane from a substantially fixed-position sheet entrance path, the apparatus comprising:

a hold-down bar and a pusher bar having quiescent positions wherein said hold-down bar resides substantially in said horizontal plane, and operates to hold down the trailing edge portion of sheets within a stack, and wherein said pusher bar is positioned a distance above said horizontal plane, the space between said bars defining an unobstructed entrance for the insertion of a sheet;
sensing means responsive to the insertion of a sheet;
and
motive means controlled by said sensing means and operative to produce synchronized substantially vertical movement of said pusher bar down onto said inserted sheet and substantially into said horizontal plane, and back to its quiescent position, as said hold-down bar moves in a substantially circular path, first toward and beyond the trailing edge of said inserted sheet, then above said inserted sheet as said sheet is held down by said pusher bar, and then back to its quiescent position.

1 more element

In combination:

a xerographic apparatus for producing graphic matter on individual flexible sheets by means including a hot roll fuser;
means defining a substantially fixed-position sheet discharge path for said sheets;
means defining a substantially fixed-position horizontal plane, vertically below said sheet disclosure path, at which said sheets are stacked;
a hold-down bar and a pusher bar, extending in a direction substantially normal to said sheet discharge path, and having quiescent positions wherein said hold-down bar resides substantially in said horizontal plane and operates to hold down the trailing edges of sheets within a stack, and wherein said pusher bar is positioned a short distance above said horizontal plane, the space between said bars defining an unobstructed entrance for the insertion of a sheet;
sensing means responsive to the insertion of a sheet;
and
motive means controlled by said sensing means and operative to produce one cycle of movement of said hold-down and pusher bars for each inserted sheet, said movement being synchronized to produce substantially vertical movement of said pusher bar down onto said inserted sheet and substantially into said horizontal plane, and back to its quiescent position, as said hold-down bar moves in a substantially circular path, first toward and beyond the trailing edge of said inserted sheet, then above said inserted sheet as said sheet is held down by said pusher bar, and then back to its quiescent position.

4 more elements

Dependencies are inferred from the claim text.

Sheet stacking apparatus

Life of this patent

Sheet stacking apparatus

Life of this patent

Abstract

Claims15