Xerox Corporation

Nicholas Frank

Peter R Watson

Paul Swallow

Carl R Chapman

A sheet feeding apparatus includes a sheet stack container comprising opposed vertical walls between which sheets are stacked and a sheet feeder for feeding sheets off the top of the stack in a direction between the walls and parallel with the walls. The container includes a platform for elevating the stack into contact with the sheet feeder, and pusher members in one of the walls for urging the stack against the other wall. The pusher members are positioned at or near the top of the stack, and act only on a minor proportion of the stack height when the maximum stack height is contained in the container. First and second pusher members are provided, the first pusher member being urged towards the stack by a relatively strong spring, and acting on sheets near the top of the stack, but not on the sheets nearest the top of the stack, and the second pusher member being urged towards the stack by a relatively light spring, and acting on the sheets nearest the top of the stack. The platform pushes the first pusher member away from the stack when the stack is almost depleted to prevent buckling of the stack.

Sheet feed apparatus

The invention relates to a sheet feed apparatus which is particularly, although not exclusively, useful in a xerographic copying machine. The apparatus includes a roller assembly including first and second rollers, the first roller being arranged to engage the top sheet in a stack of sheets and advance the sheet to a nip defined between the second roller and a retard member. The roller assembly is attachable to a support such as a feedhead cover, by means of a snap-in connection whereby, when assembled to the support way, the second roller is operably coupled to a drive gear. In order to facilitate connections between a drive shaft through the second roller and the drive gear, the drive shaft is biassed towards the drive means by a compression spring, and is mounted for movement along the axis of the second roller against the bias of the compression spring.

A laser printer has a circulating photoreceptor belt 20 and a transfer station 4 at which toner images are transferred from the belt to copy sheets. Each copy sheet is registered, upstream of the transfer station 4, in the nip of registration rolls 12 before being fed to the transfer station. The copy sheet is fed to the registration rolls 12 (which at that time are stationary) by feed rolls 13, 14 which continue to rotate so that a buckle is formed in the sheet to assist in removing any de-skew. When the sheet has been registered, the registration rolls 12 are rotated and, initially, are accelerated to a speed about 20% greater than the normal operating speed. That has the effect of decreasing the amount of buckle in the sheet before the trail end of the sheet reaches the registration rolls. When the buckle has been reduced, the speed of the rolls is reduced to the normal operating level, which is typically about the same as the speed of the photoreceptor belt.

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London, United Kingdom

Nicholas Frank