Paper feed device and paper feed method

摘要

A paper feed device and a paper feed method that, even in a case where the number of paper sheets remaining on a paper sheet stacking plate is low, allow paper sheet changing to be facilitated. There are included a paper sheet push-up member for pushing up from below a paper sheet batch on the paper sheet stacking plate and a push-up member driving device that, in a case where the number of paper sheets in the paper sheet batch on the paper sheet stacking plate is not higher than the prescribed number, makes at least a part of the paper sheet push-up member protrude upward beyond the upper surface of the paper sheet stacking plate. Thus, a lower surface of the paper sheet batch placed on the paper sheet stacking plate is pushed up from below, thereby creating a clearance.

主权项

1. A paper feed device, comprising:
a paper sheet housing case that is open upward; a paper sheet stacking plate that is provided in the paper sheet housing case in such a manner as to be movable in an up-down direction, on an upper surface of which a batch of paper sheets are placed in a state of being stacked in the up-down direction; and a lift-up mechanism that causes the paper sheet stacking plate to ascend as a number of the paper sheets on the paper sheet stacking plate decreases so that an uppermost one of the paper sheets in the paper sheet batch on the paper sheet stacking plate is positioned at a prescribed paper feed height, wherein the paper feed device further comprises:
a push-up member for pushing up from below the paper sheet batch on the paper sheet stacking plate; anda push-up member driving device that, in a case where the number of paper sheets in the paper sheet batch on the paper sheet stacking plate is higher than a prescribed number, causes the push-up member to be positioned not higher than the upper surface of the paper sheet stacking plate, and in a case where the number of paper sheets in the paper sheet batch on the paper sheet stacking plate is not higher than the prescribed number, makes at least a part of the push-up member protrude upward beyond the upper surface of the paper sheet stacking plate so that a part of a lower surface of a lowermost one of the paper sheets in the paper sheet batch placed on the paper sheet stacking plate is pushed up from below by the push-up member, thereby creating a clearance between the lower surface of the lowermost one of the paper sheets and the upper surface of the paper sheet stacking plate,a pick-up roller for feeding out the uppermost one of the paper sheets to outside the paper sheet housing case is provided at the paper feed position,the paper sheet housing case is mountable and demountable with respect to a housing that houses an image forming portion that forms an image on a paper sheet fed out by the pick-up roller,the lift-up mechanism is configured to, when the paper sheet housing case is demounted from the housing, cause the paper sheet stacking plate to descend to be positioned at a prescribed standby position below the paper feed position,at a prescribed position on the paper sheet stacking plate, a through hole is formed to penetrate through the paper sheet stacking plate in the up-down direction,on a bottom wall portion of the paper sheet housing case, in a planar view, the push-up member is disposed at a position corresponding to the through hole,the push-up member driving device includes a compression coil spring that elastically supports the push-up member in such a manner that the push-up member is movable in the up-down direction with respect to the bottom wall portion of the paper sheet housing case,the compression coil spring is configured such that, in a case where the paper sheet stacking plate has been moved to the standby position by the lift-up mechanism, a number of paper sheets in a paper sheet batch on the paper sheet stacking plate is higher than the prescribed number, the compression coil spring is compressed under an own weight of the paper sheet batch, so that the push-up member is positioned not higher than the upper surface of the paper sheet stacking plate, and in a case where the number of paper sheets in the paper sheet batch is not higher than the prescribed number, against the own weight of the paper sheet batch, the compression coil spring pushes up the push-up member so that at least a part of the push-up member protrudes upward beyond the upper surface of the paper sheet stacking plate, thereby creating a clearance between a lower surface of the lowermost one of the paper sheets and the upper surface of the paper sheet stacking plate, andwhen the paper sheet stacking plate is moved from the standby position to the paper feed position by the lift-up mechanism, the upper surface of the paper sheet stacking plate moves up away from the push-up member.