Sheet buckle sensing

Claim 2

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.

Claim 3

A sheet transport system as in claim 1, wherein the receiving surface includes a vacuum means for drawing the sheets toward the receiving surface.

Claim 4

A sheet transport system as in claim 2, wherein the vacuum means includes a plenum and wherein the separation determining means includes means for sensing pressure within the plenum.

Claim 5

A sheet transport system as in claim 3, wherein the receiving surface comprises a movable belt.

Claim 6

A sheet transport system as in claim 1, wherein the second drive includes means for initializing the speed thereof to drive the sheets at a speed higher than the speed at which the first drive means drives the sheets.

Claim 7

A sheet transport system as in claim 1, wherein the speed control means controls the second drive means.

Claim 8

A sheet transport system as in claim 4, wherein a portion of the belt is offset from a linear path extending between the first drive means and the second drive means.

Claim 9

A sheet transport system as in claim 1, further comprising a deflector adjacent a downstream end of the sheet receiving surface for deflecting the copy sheet away from a linear path extending between the first drive means and the second drive means.

Claim 10

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.

Claim 11

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.

Claim 12

A copier as in claim 9, wherein the receiving surface includes a vacuum means for drawing the copy sheet toward the transport surface.

Claim 13

A copier as in claim 9, wherein the vacuum means includes a plenum and means for detecting pressure in the plenum.

Claim 14

A copier as in claim 9, wherein the second drive means includes means includes means for initializing the speed thereof to drive the copy sheets at a speed greater than the speed at which the first drive means drives the copy sheets.

Claim 15

A copier as in claim 9, wherein the controller means comprises means for controlling the speed of the second drive means.

Claim 16

A copier as in claim 9, wherein the transport surface is movable.

Claim 17

A copier as in claim 14, wherein the transport surface includes a vacuum means for drawing the copy sheet against the transport surface.

Claim 18

A copier as in claim 15, wherein the transport surface is a movable belt.

Claim 19

A copier as in claim 16, wherein a portion of the belt is offset from a linear path extending between the first drive means and the second drive means.

Claim 20

A copier as in claim 9, further comprising a deflector adjacent a downstream end of the sheet receiving surface for deflecting the copy sheet away from a linear path extending between the first drive means and the second drive means.

Claim 21

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.

Claim 22

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.

Claim 23

A copier as in claim 19, wherein the controller slows the speed of the fuser roll in inverse relationship to the level of vacuum sensed by the sensor.

Claim 24

A copier as in claim 19, wherein the pressure sensor is a switch that activates and deactivates the fuser roll drive.

Claim 27

A method as in claim 18, wherein the second speed is higher than the first speed.

Claim 28

A method as in claim 18, wherein the step of receiving the sheet on the receiving surface includes establishing a vacuum to draw the sheet against the receiving surface, and the step of sensing separation between the receiving surface and the sheet comprises sensing said vacuum.

Claim 29

A method as in claim 20, and further comprising the steps of transferring an unfused toner image onto the sheet at the first work station and fusing the toner image on the sheet at the second work station.

Claim 30

A method as in claim 22, further comprising the step of conveying a sheet on the receiving surface along a path offset from a linear path extending between the first and the second work stations.

Claim 31

A method as in claim 22, further comprising the step of deflecting a sheet away from a linear path extending between the first and the second work stations.