Copying apparatus and method of copy sheet registration

Claim 2

Copying apparatus including means for moving individual copy sheets along a path into registered contact with an imaging member for transfer of an image from the image from the imaging surface to a sheet, and means for sensing the passage of a sheet past a reference point; characterised by control means coupled to said means for sensing for calculating the error, if any, of the-speed and position of said sheet with respect to said imaging member and generating control signals to said means for moving to adjust the speed of said sheet to achieve and maintain a position and speed match between the sheet and the member.

Claim 3

The apparatus of Claim 1 including : means for generating speed signals related to the speed of said imaging surface and said copy sheet respectively; means for monitoring the position registration of said copy sheet with respect to an image on said imaging surface; and control means coupled to outputs from said means for generating and said means for monitoring to compare the difference if any between position and speed registration, and further coupled to said means for moving to register the image with the sheet at the point of image transfer.

Claim 4

The apparatus of Claim 2 wherein the control means comprises: a) means for comparing the speed of said sheet with the speed of said image and indicating the different in said speeds; b) means for calculating the difference, if any, in position registration between the sheet and the image; and c) means responsive to said means for comparing and said means for calculating to determine how the sheet speed should be changed to achieve a match in both speed and position registration before said sheet moves into image transfer relation with said imaging surface.

Claim 5

The apparatus of Claim 2 or Claim 3 wherein the control means comprises storage means for storing updated indications of said position and speed registration as the sheet moves toward the imaging surface.

Claim 7

A xerographic copier including the apparatus of Claim 1 and comprising: a photoconductive belt member for carrying xerographic images to an image transfer station, said belt member being capable of carrying multiple images spaced about its periphery and including spaced markings separate by a distance equal to the image pitch; copy sheet feeding means mounted to said copier for feeding successive copy sheets to the transfer station to receive xerographic images from the belt member; said sheet feeding means including at least one endless drive belt having one or more fingers for driving sheets along a path of sheet travel; drive means for moving said drive belt along the path of travel; means for moving said photoconductive belt member and accompanying images at a constant rate so that said images approach said transfer station at said constant rate, sensing means for monitoring the drive belt movement of said means for moving and generating a clock signal with a frequency related to the speed of said drive belt; image sensing means for sensing the movement of said spaced markings past said image sensing means and generating an image signal each time a marking is sensed; drive sensing means for monitoring the speed with which the drive means moves said drive belt and for generating a speed signal with a frequency related to the speed of said endless drive belt; sheet sensing means for sensing sheet position and generating a sheet position signal at a specific poiint of sheet movement in relation to said transfer station; and control means coupled to said copier sensing, image sensing, drive sensing and sheet sensing means to receive sensor input signals and determine whether an image is leading, lagging or registered with an associated copy sheet and for further determining the relative speeds of said image and copy sheet, said control means configured to control operation of said drive means to speed up, brake or maintain the speed with which the drive belt moves to achieve and maintain both a position and speed registration between the image and an associated copy sheet prior to the meeting of said sheet and said image at the transfer station.

Claim 8

The apparatus of Claim 6 wherein the drive means comprises a direct current motor and further comprises a drive circuit which can be engergized to drive said motor, allow said motor to coast, or brake said motor, said control means comprising a programmable controller coupled to said drive circuit for energizing said circuit in response to the sensing of said clock, image, speed, and position signals.