Patent Application
20100072697
This invention relates to media or paper-handling systems and, more specifically, to a media transport system particularly useful in pre and post marking processes.
While the present invention can be used in any suitable marking system, it will be described herein for clarity as used in electrostatic marking systems such as electrophotography or xerography.
Marking systems that transport paper or other media are well known in the art. These marking systems include electrostatic marking systems, non-electrostatic marking systems, printers or any other marking system where paper or other flexible media or sheets are transported internally.
By way of background, in marking systems such as xerography or other electrostatographic processes, a uniform electrostatic charge is placed upon a photoreceptor belt or drum surface. The charged surface is then exposed to a light image of an original to selectively dissipate the charge to form a latent electrostatic image of the original. The latent image is developed by depositing finely divided and charged particles of toner upon the belt or drum photoreceptor surface. The toner may be in dry powder form or suspended in a liquid carrier. The charged toner, being electrostatically attached to the latent electrostatic image areas, creates a visible replica of the original. The developed image is then usually transferred from the photoreceptor surface to an intermediate transfer belt or to a final support material such as a paper sheet. When the paper is fed to the system from a paper stack of a feeder mechanism, some papers could be off the home position by many mm, and these fed paper sheets need to be deskewed and laterally registered option (1) into position upon placement on the transport belt or option (2) into position before contacting the image on the photoconductive surface. This is necessary because as the sheets move to the transfer station and approach the imaged photoconductor surface, they need to be in perfect alignment with the toned image on the photoconductive layer for proper image transfer to the sheet to take place. Also, many paper-moving systems are used for transporting printed sheets so they may be formed into books and the like. The present invention is useful in marking systems in both pre and post paper transport systems.
In the present system a number of sensors evaluate the positioning of the sheet as the paper sheet makes initial contact and when it continues down the transport path, and convey this information to a controller that will regulate and control progression of the sheet (including lateral registration) before it reaches the finishing station or the imaged photoconductive surface for image transfer to the sheet. In high speed marking systems, reaction and action time is important. Some prior art registration systems are too slow to be useful in today's high speed systems. The present invention allows for lateral reset while the paper lead edge is present in the gripper means.
In recent years, most of the media transport devices use nip rolls and a corresponding baffle system. Due to the nature of tolerance variations on those parts, there is slippage skew and walk observed which require an “in-line” additional registration subsystem to correct errors. Often these in line subsystems have been found to be inadequate.
The present invention includes the use of multiple leading edge (LE) gripping segments comprised of two aligned registration collapsible rolling arms and corresponding partially centric bar. The LE gripping segments travel, synchronized by device timing on two timing belt conveyors. A buckled LE of the document in the gripping segment at the beginning of the transport is grasped between pairs of collapsible rolling arms and the bar. Those contacts provide enough force to maintain LE registration throughout transport until final release. The gripping segment delivers the document to the final destination, including but not limited to, exit transport nips or temporary/final compiling area in finishing devices. Cross-process registration of the acquired document is achieved by sliding of the gripping bar in transverse direction using a controlled relative, differential motion between two drivers along with the gripped document. Sensors and a controller with proper software provide the desired activation and control of this system.
The apparatus of the present transport assembly includes a laterally spaced flat bed baffle panels positioned over at least two conveyor belts. Attached to these belts via the spaces between the baffle sections are gripping bars that contact and hold the leading edge of the paper sheet in registration. During the initial advancement of the document, the document leading edge enters the buckling chamber defined between entrance baffles and then to the gripping bar and to the adjacent rolling elastomeric element of collapsible arms. Initially, the transport system stops at that first contact position to acquire and hold the leading edge of the sheet. The entire sheet is then transported by movement of the conveyor belts until it reaches its final destination where the gripping bar releases the document for further processing.
This invention provides a convenient, easy to use system for paper transport and paper registration. It features multiple lead edge gripper segments attached to inboard and outboard conveyor belts which are driven by a single motor. When the sheet is received, the transport is stationary and lead edge de-skew registration is accomplished with a buckle chamber. After LE registration is done, the acquisition of the sheet occurs by rolling the grippers over the top of the sheet using a curvature of the transport belts. At a time when the sheet(s) are transported, a second motor drives a center mounted conveyor belt. A differential position between the center belt and the outside belt provides in one embodiment a lateral motion to the sheet through a pin/follower/cam arrangement. This provides lateral sheet registration control. This is a convenient and effective mechanism for achieving lateral motion in a gripper bar transport.
In
In
With reference to Detail B of
In
In
In
In
A. charge station
B. exposure station
C. development station
D. transfer station
E. fusing station
F. finishing station.
As noted earlier, a finishing station F may contain the transport apparatus of the present invention as may any other part of the illustrated marking system of
It is believed that the foregoing description is sufficient for purposes of the present application to illustrate the general operation of a printing machine incorporating the paper transport apparatus of the present invention therein. Although the apparatus of the present invention is particularly well adapted for use in an electrophotographic reproducing machine, it will become apparent from the following discussion that the finishing apparatus of the present invention is equally well suited for use in a wide variety of printers and other non-marking document handling systems where conveyance of paper or other sheets is desired.
In summary, the present invention provides a sheet registration and conveyance system for transporting and registering these sheets via gripping of leading edges of these sheets. This system comprises at least one endless, movable conveyor belt, gripping segments attached to the conveyor belt(s), and baffle panels with separations positioned over an upper portion of these conveyor belt(s). The gripping segments are horizontally movable through these baffle separations while attached to said conveyor belt. The gripping segments comprise a gripper bar and a pivotable tension arm having an elastomeric roller(s) attached to its terminal portion. The gripper bar and the elastomeric roller are configured to securely hold a leading edge of the sheet and enabled to transport this sheet through a transport path from initial paper contact to an exit point for the paper sheet.
The gripper bar comprises an outside curved portion enabled to guide the sheet between the gripper bar and the elastomeric roller(s). The gripping segments are configured to be moved or shifted laterally and to be positioned in conformance with a desired paper or sheet exit location or position.
The tension arm is spring loaded to provide sufficient sheet-holding pressure on the elastomeric roller(s). The baffle panels are separated from each other to provide a space for each gripping segment to move therethrough while being connected to the endless movable conveyor belt. The leading edge is enabled to be gripped and released by the gripping segment, this gripping segment functions and is controlled via sensors and a controller connected to the system. A cross process registration or offset of the sheet is provided by differential speeds and horizontal shifting of the gripping segments. The conveyor belt is driven by a motor(s) and driving rolls in contact therewith, a speed of the conveyor belt and attached gripping segments is synchronized and determined by a system controller with appropriate pre-programmed software.
This invention provides an effective sheet registration and conveyance system for transporting and registering sheets via gripping of leading edges of the sheets. This system as above noted comprises two endless movable conveyor belts, at least two gripping segments attached to these conveyor belts and baffle panels with at least two panel separations positioned over an upper portion of said conveyor belts. The at least two gripping segments are horizontally movable through the baffle separations while both gripping segments are attached to different conveyor belts.
The gripping segments comprise a gripper bar and a pivotable tension spring loaded arm having two elastomeric roller(s) attached to its inboard terminal portions. The two gripper bars and the elastomeric roller are configured to securely hold a leading edge of the sheet and to transport this sheet through a transport path from initial leading edge paper contact to a paper sheet exit point. The gripping segments are enabled to slide in a transverse direction for cross process registration.
It will be appreciated that variations of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.
