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US 4,900,008 AGranted
Sheet clamping arrangement for rotatable drums
AssigneePolaroid Corporation
InventorsJune C. Fichter, Kenneth A. McAuley
Life of this patent
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AssigneePolaroid Corporation
InventorsJune C. Fichter, Kenneth A. McAuley
Estimating the term…
A sheet clamping system for rotatable drums especially suited for use in retaining and positioning successive receiver sheets for high speed printers. The clamping system enables unidirectional movement of a sheet during delivery of the sheet to the drum from a supply stack, during clamping of the leading edge of the sheet to the drum followed by clamping of the trailing edge of the same sheet to the drum and during subsequent release and delivery of the sheet to a receiving stack or tray. The system features a cam system for actuating respective leading and trailing edge clamps which is supported on the same shaft to which drum driving rotation is supplied by a drive motor. In one embodiment where the drive motor is reversible, a one-way clutch connection of the drum to the shaft enables drum rotation during one rotational direction of the shaft whereas clamping bar actuation is effected by rotation of the shaft in the opposite direction while holding the drum. In an alternative embodiment, the drum is fixed to the shaft which is driven in a working direction only by a first relatively high speed motor, the cam system is rotatable on the shaft, and a second relatively slow speed stepping motor drives the cam system and the drum during sheet loading and unloading operations.
In a sheet clamping system for a rotatable drum having a leading edge clamping bar movable between retracted and clamping positions, a trailing edge clamping bar movable between radially displaced retracted and clamping positions, and means for operating said leading edge clamping bar, said trailing edge clamping bar and said drum so that a sheet passed between said drum and said trailing edge clamping bar in the retracted position thereof is clamped to said drum at its leading edge by said leading edge clamping bar, drawn through said trailing edge clamping bar while same is retained in a stationary retracted position during drum rotation with said leading edge clamping bar until the trailing edge of the sheet registers with and is clamped to the drum by said trailing edge clamping bar, the improvement comprising:
In a sheet clamping system for a rotatable drum having a leading edge clamping bar, a trailing edge clamping bar, means for supporting said leading edge clamping bar for rotation with said drum and for movement between a sheet clamping position against the drum periphery and a retracted position spaced from the drum periphery, and means for supporting said trailing edge clamping bar for movement between a sheet clamping position against the drum periphery and a retracted position spaced from the drum periphery, and means for selectively retaining said trailing edge clamping bar supporting means against rotation with said drum, the improvement comprising:
In a sheet clamping system for a rotatable drum having a leading edge clamping bar, a trailing edge clamping bar, means for supporting said leading edge clamping bar for rotation with said drum and for movement between a sheet clamping position against the drum periphery and a retracted position spaced from the drum periphery, and means for supporting said trailing edge clamping bar for movement between a sheet clamping position against the drum periphery and a retracted position spaced from the drum periphery, and means for selectively retaining said trailing edge clamping bar supporting means against rotation with said drum, the improvement comprising:
In a sheet clamping system for a rotatable drum having a leading edge clamping bar, a trailing edge clamping bar, means for supporting said leading edge clamping bar for rotation with said drum and for movement between a sheet clamping position against the drum periphery and a retracted position spaced from the drum periphery, and means for supporting said trailing edge clamping bar for movement between a sheet clamping position against the drum periphery and a retracted position spaced from the drum periphery, and means for selectively retaining said trailing edge clamping bar supporting means against rotation with said drum, the improvement comprising:
A sheet clamping system for rotatable drums, said system comprising:
Dependencies are inferred from the claim text.