Feed mechanism for feeding sheets from a stack to a printer
A feed mechanism for a printer includes a support structure. A sheet feed assembly is mounted on the support structure to feed sheets from a stack of sheets to the printer along a feed path. A nozzle assembly is movably mounted on the support structure and includes at least one nozzle that opens towards the stack of sheets. A displacement mechanism moves the nozzle assembly reciprocally between the stack of sheets and the sheet feed assembly. A gas supply is connected to the nozzle assembly and is operable so that a gas stream emitted from the, or each, nozzle penetrates a first sheet in the stack to generate a cushion of gas between the first sheet and a second sheet, thereby lifting the first sheet from the second sheet. The gas supply is reversible so that the first sheet can be retained against the nozzle assembly as the nozzle assembly is moved towards the feed assembly such that the feed assembly can feed the first sheet along the feed path.
1 . A feed mechanism for a printer, the feed mechanism comprising
a support structure;
a sheet feed assembly mounted on the support structure to feed sheets from a stack of sheets to the printer along a feed path;
a nozzle assembly that is movably mounted on the support structure and includes at least one nozzle that opens towards the stack of sheets;
a displacement mechanism for moving the nozzle assembly reciprocally between the stack of sheets and the sheet feed assembly; and
a gas supply that is connected to the nozzle assembly and is operable so that a gas stream emitted from the, or each, nozzle penetrates a first sheet in the stack to generate a cushion of gas between the first sheet and a second sheet, thereby lifting the first sheet from the second sheet, the gas supply being reversible so that the first sheet can be retained against the nozzle assembly as the nozzle assembly is moved towards the feed assembly such that the feed assembly can feed the first sheet along the feed path.
2 . A feed mechanism as claimed in claim 1 , in which the sheet feed assembly includes a roller assembly having at least one pair of feed rollers, the feed path being defined between the feed rollers.
3 . A feed mechanism as claimed in claim 1 , in which the nozzle assembly includes an elongate element that is dimensioned to span the stack of sheets, the displacement mechanism including a pair of swing arms, each swing arm being connected, at one end, to a respective end of the elongate element, a shaft to which opposite ends of the swing arms are connected and a motor that is connected to the shaft to rotate the shaft, thereby moving the elongate element, the, or each, nozzle being mounted on the elongate element.
4 . A feed mechanism as claimed in claim 3 , in which a plurality of nozzles are mounted on the elongate element to span the stack of sheets.
5 . A feed mechanism as claimed in claim 4 , in which the gas supply comprises an air blower in fluid communication with a number of the nozzles and a vacuum pump in fluid communication with the remaining nozzles.
6 . A feed mechanism as claimed in claim 5 , in which an outlet manifold is connected to the air blower and to said number of nozzles with flexible hoses and an inlet manifold is connected to the vacuum pump and to said remaining nozzles with further flexible hoses.