Browse Prior Art Database

SKIP HITCH

IP.com Disclosure Number: IPCOM000027188D
Original Publication Date: 1995-Aug-31
Included in the Prior Art Database: 2004-Apr-07
Document File: 2 page(s) / 129K

Publishing Venue

Xerox Disclosure Journal

Abstract

The present disclosure relates to a sheet gripper bar conveyor control system that accurately controls the position of a gripper bar (and the sheet it is holding) relative to a photoreceptor during transfer of a toned image to a sheet in a multicolor printer or copier. In a multipass color printer, tight control on the gripper bar positioning tolerances and correction of any gripper bar movement system to photoreceptor speed mismatch is essential to layering properly registerd multicolored images on a sheet. The "skip hitch" system disclosed herein was developed to allow looser piece part tolerances and less accurate velocity control of the gripper bar conveyor system relative to the photoreptor. The term skip hitch is used to decribe the color registration skip (or conveyor position "slip") that modifies sheet position during the transfer process. The "hitch" term relates a position correction that the gripper bar conveyor or photoreceptor makes in slowing down or speeding up for a finite period of time to obtain a desired position relationship to each other.

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XEROX DISCLOSURE JOURNAL

SKIP HITCH

Richard M. Dastin Kenneth J. Mihalyov

Proposed Classification
U.S. C1.358/401 Int. C1. H04n 1/00

The present disclosure relates to a sheet gripper bar conveyor control system that accurately controls the position of a gripper bar (and the sheet it is holding) relative to a photoreceptor during transfer of a toned image to a sheet in a multicolor printer or copier. In a multipass color printer, tight control on the gripper bar positioning tolerances and correction of any gripper bar movement system to photoreceptor speed mismatch is essential to layering properly registerd multicolored images on a sheet. The "skip hitch" system disclosed herein was developed to allow looser piece part tolerances and less accurate velocity control of the gripper bar conveyor system relative to the photoreptor. The term skip hitch is used to decribe the color registration skip (or conveyor position "slip") that modifies sheet position during the transfer process. The "hitch" term relates a position correction that the gripper bar conveyor or photoreceptor makes in slowing down or speeding up for a finite period of time to obtain a desired position relationship to each other.

In a multipass, multicolor system architecture, the gripper bar will grip the copy sheet and transport it through the transfer zone. The gripper bar conveyor controls the kinematics and.dynamics of the leading edge of that sheet. The gripper bar carries the sheet leading edge to meet the photoreceptor at a precise point and at a precise velocity. During that meeting, the sheet is weakly attached to the photoreceptor by the action of the transfer mechanism which typically involves electrostatic and mechanical forces as imparted by such devices as corotrons and bias rolls. Soon after the start of the transfer, the gripper bar on its reciprocating belt conveyor and underlying vacuum drum initiates a turn as it progresses through its recirculative loop.

Due to the difficulty in precisely matching the velocity of the photoreceptor to the the velocity of the gripper bar, the gripper bar recirculative loop turn is typically made as close as possible to the image transfer point. In entering this first turn in the loop, it is difficult to prevent the gripped leadi...