Sheet clamping device
AssigneeRicoh Company, Ltd.
InventorMichio Umezawa
Life of this patent
Estimating the term…
Abstract
A sheet is disposed around the outer peripheral surface of a drum. The drum is provided with sheet suction holes for attracting the sheet against the drum surface. The sheet suction holes extend through the drum from the interior to the exterior thereof, and are disposed in a plurality of circumferentially spaced rows. Each of the rows includes a plurality of sheet suction holes and is connected to suction means, which is operable to withdraw air outside the drum into the interior thereof through the row of suction holes. At least the leading edge of the sheet is retained by a sheet seizing claw which is movable toward or away from the drum surface. The claw is urged into abutment against the drum surface under the influence of a centrifugal force as the drum rotates.
Claims58
A sheet clamping device for holding a sheet around a drum, comprising a plurality of rows of sheet suction holes formed in the peripheral surface of a drum to provide communication between the interior and the exterior of the drum, the rows being spaced apart circumferentially of the drum, suction means including only one vacuum pump communicating with the suction holes of the respective rows for applying suction to said holes to withdraw air into the interior of the drum, and means for controlling the timing of application of suction to the respective rows of sheet suction holes, thereby beginning the attraction of different parts of the sheet to the drum from inside the drum at different times.
A sheet clamping device for holding a sheet around a drum, comprising a plurality of rows of sheet suction holes formed in the peripheral surface of a drum to provide communication between the interior and the exterior of the drum, the rows being spaced apart circumferentially of the drum, suction means communicating with the suction holes of the respective rows for applying suction to said holes to withdraw air into the interior of the drum, means controlling the timing of application of sucton to the respective rows of sheet suction holes, thereby beginning the attraction of different parts of the sheet to the drum from inside the drum at different times, a sheet seizing claw pivotally mounted to the drum in space relation therewith, means connected to said claw for urging it resiliently away from the drum surface, and holding means for bringing said claw towards said drum surface for holding a sheet thereto;
- said holding means including a number of said sheet suction holes being disposed to attract said claw to said drum surface when the leading edge of a sheet is first attracted by suction to said drum.
A sheet clamping device for holding a sheet around a drum, comprising a plurality of rows of sheet suction holes formed in the peripheral surface of a drum to provide communication between the interior and the exterior of the drum, the rows being spaced apart circumferentially of the drum, suction means communicating with the suction holes of the respective rows for applying suction to said holes to withdraw air into the interior of the drum, means controlling the timing of application of suction to the respective rows of sheet suction holes, thereby beginning the attraction of different parts of the sheet to the drum from inside the drum at the different times, and a sheet seizing claim pivotally mounted to the drum in space relation therewith, and means including a weight connected to said claw for pivoting said claw toward the drum during high speed rotation of the drum to hold a sheet between said claw and said drum.
Dependencies are inferred from the claim text.