Sheet buckle sensing
AssigneeXerox Corporation
InventorMichael A. Malachowski
Life of this patent
Estimating the term…
Abstract
A sheet transport system incorporating a control for matching drive speeds imparted to a sheet extending between adjacent workstations is disclosed. The copy sheet is engaged by a receiving surface disposed between the workstations and is adhered to the receiving surface by vacuum. The copy sheet follows a path offset from a linear path extending between the workstations. Fuser rolls are driven at a slightly higher speed to tension the copy sheet and lift it from the transport surface. The lifting is detected by a sensor for sensing the vacuum in a plenum communicated with the receiving surface. The drive speed of the fuser rolls is controlled in accordance with the signal from the sensor.
Claims27
A transport system for serially transporting sheets comprising:
- a first zone;
- first drive means at the first zone for driving the sheets;
- a second zone located downstream of the first zone a distance less than the length of said sheets;
- a second drive means at the second zone for driving the sheets;
- a sheet receiving surface disposed between the first drive means and the second drive means for receiving a portion of a sheet extending between the first and second drive means;
- separation determining means for determining separation of a sheet from the sheet receiving surface by tension resulting from a speed differential between the first drive means and the second drive means;
- and
- speed control means responsive to the separation determining means for controlling a speed differential between the first and the second drive means, to maintain the sheets toward the receiving surface.
A copier for forming images on copy sheets comprising:
- an image forming station for forming an unfused toner image on a copy sheet;
- a drive for driving the copy sheet through the image forming station;
- a fuser station located downstream of the imaging station for fusing the toner image on the copy sheet;
- a second drive for driving the copy sheet through the fuser station, said second drive being linearly spaced from the second drive by a distance less than a length of the copy sheet in the direction of drive of a copy sheet;
- a transport surface disposed between the first drive and the second drive for receiving a portion of a copy sheet extending from the first drive means toward the second drive means;
- a determining means for determining separation between a copy sheet and the transport surface by tension imparted to the copy sheet;
- and
- means responsive to the determining means for controlling a relative speed differential between the first and second drive means, whereby the copy sheet is disposed toward the transport surface.
A copier for forming fusible images on a copy sheet comprising:
- a movable photoreceptor for forming images of fusable toner;
- means for moving a copy sheet as the fusable toner is transferred from the photoreceptor onto the copy sheet;
- a fuser roll located downstream of the photoreceptor by a linear distance less than the length of a copy sheet in the direction of travel from the photorecptor to the fuser roll;
- a fuser roll drive for rotating the fuser roll;
- a transport system disposed between the photoreceptor and the fuser roll for conveying a copy sheet from the photoreceptor to the fuser roll, the transport system including a movable surface for conveying the copy sheet and a vacuum means for drawing the copy sheet against the movable surface, the vacuum means including a vacuum plenum, the vacuum level in the plenum being related to the area of a copy sheet disposed against the movable surface;
- a pressure sensor for sensing the vacuum in the plenum;
- and
- a controller for controlling the speed of the fuser roll drive in response to the vacuum sensed by the sensor.
A method for controlling the transfer of a sheet between work stations comprising the steps of:
- driving a sheet at a first speed at a first work station;
- receiving a leading portion of the sheet on a receiving surface;
- moving the leading edge of the sheet to a second work station while a trailing edge of the sheet is disposed in the first work station;
- initially driving the leading edge of the sheet at the second work station at a second speed different from the first speed, whereby the sheet is separated by tension from the receiving surface;
- sensing the separation of the sheet from the receiving surface;
- and
- adjusting the speed differential between the first speed and the second speed in response to sensing of said separation to reduce the separation between the sheet and the receiving surface.
Dependencies are inferred from the claim text.