An equipment of accumulation of sheets forms a stack of sheets on an accumulation plane by means of driving belts and diverters arranged along the path of the sheets and jump on the accumulation plane. The height of the jump is modified by shifting vertically the accumulation plane with respect to the diverters according to number and/or thickness of the sheets. The diverters can be shifted according to the length of the sheets to be accumulated, while a series of arrest lugs delimits at the rear the area of collection of the sheets and a forwarding mechanism with a pair of output rollers forwards the stack of accumulated sheets when the lugs are released.

A paper sheet storage device includes a storage space in which paper sheet is stored; a mounting table that is provided in the storage space and on which the paper sheet is accumulated and placed; a support base that supports the mounting table; a first lifting lowering mechanism that lifts and lowers the mounting table between a high position and a low position relative to the support base; and a second lifting lowering mechanism that lifts and lowers the support base in the storage space. The support base and the first lifting lowering mechanism are disposed within a projection area in which the mounting table is projected on a plane orthogonal to a lifting lowering direction in which the support base is lifted and lowered by the second lifting lowering mechanism.

A paper sheet storage device includes a storage space in which paper sheet is stored; a mounting table that is provided in the storage space and on which the paper sheet is accumulated and placed; a support base that supports the mounting table; a first lifting lowering mechanism that lifts and lowers the mounting table between a high position and a low position relative to the support base; and a second lifting lowering mechanism that lifts and lowers the support base in the storage space. The support base and the first lifting lowering mechanism are disposed within a projection area in which the mounting table is projected on a plane orthogonal to a lifting lowering direction in which the support base is lifted and lowered by the second lifting lowering mechanism.

To ensure reliable and productive processing of printed sheets into stacks, a sheet stacker includes: a flipping device for flipping a sheet with respect to the sheet's orientation before being received by the flipping device onto a stack support or a stack of sheets on the stack support; a sensor assembly for detecting an out-of-plane deformation of a top sheet with respect to the underlying stack support or a stack of sheets on the stack support at least for each sheet added to the stack; and a controller configured to determine from data from the sensor assembly whether the top sheet was successfully flipped and stacked.

A post-processing apparatus includes a tray receiving an ejected recording medium, a moving mechanism vertically moving the tray, a driving source driving the moving mechanism, a member pressing, from vertically above, a recording medium ejected to the tray, a rotational-driving mechanism driving the member so that the member rotates in a first direction away from an apparatus body when the tray is moved upward by the moving mechanism and that the member rotates in a second direction toward the apparatus body when the tray is moved downward by the moving mechanism, a rotation-angle limiting unit limiting a rotation angle of the member when the member is driven to rotate in the first direction and to rotate in the second direction, and a rotational-force limiting mechanism idling when a rotational force not lower than a predetermined force is applied to the rotational-driving mechanism.

A post-processing apparatus includes a tray receiving an ejected recording medium, a moving mechanism vertically moving the tray, a driving source driving the moving mechanism, a member pressing, from vertically above, a recording medium ejected to the tray, a rotational-driving mechanism driving the member so that the member rotates in a first direction away from an apparatus body when the tray is moved upward by the moving mechanism and that the member rotates in a second direction toward the apparatus body when the tray is moved downward by the moving mechanism, a rotation-angle limiting unit limiting a rotation angle of the member when the member is driven to rotate in the first direction and to rotate in the second direction, and a rotational-force limiting mechanism idling when a rotational force not lower than a predetermined force is applied to the rotational-driving mechanism.

A post-processing apparatus includes an ejection tray receiving a recording medium that is ejected, an elastic member urging the ejection tray upward in a vertical direction, a moving mechanism causing the ejection tray to move up and down in the vertical direction, and a driving source driving the moving mechanism.

A post-processing apparatus includes an ejection tray receiving a recording medium that is ejected, an elastic member urging the ejection tray upward in a vertical direction, a moving mechanism causing the ejection tray to move up and down in the vertical direction, and a driving source driving the moving mechanism.

According to one embodiment, a sheet post-processing apparatus has a sheet discharge tray, a drive motor, a power transmission breaker, a first power transmitter, a second power transmitter, and a load reducer. The sheet discharge tray stacks sheets. The drive motor raises and lowers the sheet discharge tray. The power transmission breaker can cut off power transmission from the drive motor to the sheet discharge tray when an upward external force is applied to the sheet discharge tray. The load reducer provides a reverse load to the sheet discharge tray in a reverse direction to the load generated on the sheet discharge tray due to stacking of the sheets. The load reducer is connected to the first power transmitter.

According to one embodiment, a sheet post-processing apparatus has a sheet discharge tray, a drive motor, a power transmission breaker, a first power transmitter, a second power transmitter, and a load reducer. The sheet discharge tray stacks sheets. The drive motor raises and lowers the sheet discharge tray. The power transmission breaker can cut off power transmission from the drive motor to the sheet discharge tray when an upward external force is applied to the sheet discharge tray. The load reducer provides a reverse load to the sheet discharge tray in a reverse direction to the load generated on the sheet discharge tray due to stacking of the sheets. The load reducer is connected to the first power transmitter.