Abstract: An image forming apparatus which includes a paper delivery unit which is provided as to be rockable and displaceable between an operating position close to a photosensitive drum and a standby position remote from the photosensitive drum; a supporting link system, operably coupled to the paper delivery unit, for holding the paper delivery unit at the operating position; and energizing device, operably coupled to the supporting link system, for energizing the paper delivery unit so as to move from the standby position to the operating position. The paper delivery unit includes a transferring device for transferring a toner image from the photosensitive drum onto a sheet, a tractor for feeding the sheet, disposed in the upstream of the transferring device in a paper delivery direction, and a suction feeder for holding and delivering the sheet, disposed in the downstream of the transferring device in the paper delivery direction.

Abstract: A paper delivery system having a printing unit with an upstream tractor and a downstream tractor disposed on an upstream side and a downstream side, respectively, of the paper delivery unit in the direction of paper delivery, a coupler coupling the upstream tractor and the downstream tractor to each other and a support shaft for supporting the coupler so that the coupler is movable in a direction transverse to the paper delivery direction and a resilient member positioned between the coupler and a fixed frame of the printing unit for energizing the coupler in a predetermined direction for constantly holding the coupler at a certain position in relation to the support shaft.

Abstract: A safety bar mechanism and sheet processing device having a safety bar mechanism, with which such an accident that the operator's hand is pinched between a table and peripheral devices etc. can be positively avoided whatever direction an external force exerts. The safety bar mechanism is disposed, for example, above the table on which a sheet is stacked, and comprises detector means the upper end of which is supported on a fixed part such that the detector means pivots freely in forward/backward directions and has play in upward/downward directions. When an external force works on the detector means, thereby moving the detector means upwards, forwards or backwards, a switching means is so operated as to at least stop the upward movement of the table.

Abstract: An inexpensive large-capacity paper hopper capable of energizing a paper feed table with a constant lift force irrespective of the quantity of paper sheets remaining thereon, thereby performing stable paper feeding. To achieve such a paper hopper, a paper hopper, wherein a paper feed table is lifted or lowered being kept in a horizontal condition and paper sheets stacked on the paper feed table are sequentially sent out from the top sheet for feeding, is arranged such that the paper feed table is so suspended by a wire suspending device as to be lifted or lowered in a horizontal condition, and an elastic tensile force of extension coil springs included in a lift force exerting device is so exerted to the paper feed table that the direction in which the restoring displacement of the extension coil springs takes place becomes coincident with the direction of lifting the paper feed table.