Patent Application
20150284209
The present disclosure relates to printer that includes a compiler, and more particularly, to a paddle wheel compiler for stacking cut sheet media sets on top of a non-flat stack.
Past compilers include the disc stacker shown in EP 1762523 B1 for use in a finishing apparatus that employs rubber ring scuffers to register sheets against a registration wall. A variant disc stacker is shown in U.S. Pat. No. 5,065,997 in use as an inverter and stacking apparatus and includes at least one sheet inverter wheel having at least one arcuate sheet retaining slot into which a sheet may be inserted and flipped. A type of paddle wheel compiler that also flips currency is shown in U.S. Pat. No. 7,735,621 B2.
Cut sheet stacking requires sheets to be very accurately registered to one another in compiled sets. There are many architectures of stacking machines to accomplish this. One example is the use a compiler subsystem to stack and register the sheets of each set before adding the set to the main stack of paper. This type of machine also poses problems with sheet registration. Because each set is not compiled in a separate subsystem, which would provide a clean flat surface for each set, better sheet control is needed to deal with non-flat sheet compiling conditions. The non-flat conditions on top of the main stack can be due to a number of reasons including curl, cockle, static, etc., which generally accumulate as the height of the stack grows. The final goal is to compile sets with accurate in-set registration.
In-set registration is generally accomplished with any combination of the following features: pre-compiling registration, registration walls, tamping, and scuffing. The best results are usually the result of scuffing and tamping into a registration wall. However, scuffing and tamping have fundamental limitations: scuffing can only act on the top sheet of the set and tamping requires the sheets to be free of any forces impeding lateral motion. For example, the scuffer must be withdrawn from the set or it wouldn't allow the sheets to move laterally when tamping. In machines with a compiling subsystem, sheets can be tamped in the cross process direction as well as the process direction to ensure registration against a registration wall. However, when on a main stack, that may not be flat, several fundamental problems arise: (1) only the top sheet will be re-registered against the registration wall when the scuffer is actuated. The scuffer cannot correct sheets lower in the set and there is no trail edge tamper to correct those sheets; (2) sheets can move away from registration wall, in the process direction, during side tamping. This is because of the non-flat compiling surface, stack vibration, static levitation, etc., or any combination of these; and (3) there is no trail edge tamper to tamp the sheets against the registration wall in the process direction. A trail edge tamper cannot be used because there is no separation between the main stack and the set being compiled.
Therefore, there is still a need for a compiler that stacks cut sheet media sets on top of a non-flat stack, eliminates the compiler subsystem and compiles on the main stack of paper and has the advantages of lower cost and improved speed capability.
In answer thereto, provided hereinafter is a paddle wheel compiler that includes a paddle wheel which accepts sheets from the front of the paddle wheel, unlike a disk stacker which accepts sheets from the top or back of the disk and flips the sheet. The paddle wheel compiler processes multiple sheets in one revolution of the wheel and is unique in that it maintains control of all sheets in the set, except for the top sheet during tamping. The top sheet is registered to the set with side tampers, followed by a scuffing action to register up against a registration wall in the process direction.
The disclosed system may be operated by and controlled by appropriate operation of conventional control systems. It is well known and preferable to program and execute imaging, printing, paper handling, and other control functions and logic with software instructions for conventional or general purpose microprocessors, as taught by numerous prior patents and commercial products. Such programming or software may, of course, vary depending on the particular functions, software type, and microprocessor or other computer system utilized, but will be available to, or readily programmable without undue experimentation from, functional descriptions, such as, those provided herein, and/or prior knowledge of functions which are conventional, together with general knowledge in the software of computer arts. Alternatively, any disclosed control system or method may be implemented partially or fully in hardware, using standard logic circuits or single chip VLSI designs.
The term ‘sheet’ herein refers to any flimsy physical sheet or paper, plastic, media, or other useable physical substrate for printing images thereon, whether precut or initially web fed.
As to specific components of the subject apparatus or methods, it will be appreciated that, as normally the case, some components are known per se' in other apparatus or applications, which may be additionally or alternatively used herein, including those from art cited herein. The cited references, and their references, are incorporated by reference herein where appropriate for teachings of additional or alternative details, features, and/or technical background. What is well known to those skilled in the art need not be described herein.
Various of the above-mentioned and further features and advantages will be apparent to those skilled in the art from the specific apparatus and its operation or methods described in the example(s) below, and the claims. Thus, they will be better understood from this description of these specific embodiment(s), including the drawing figures (which are approximately to scale) wherein:
Referring now to
In operation, paddle wheel assembly 10 parks with one paddle 14 on top of sheet stack 13 and one paddle 14 restrained against indexing plate 20 in order to create an opening for a sheet 11 to enter the paddle wheel compiler 8. Damper hook 18 is parked in front of registration wall 30, awaiting sheet 11 to be driven underneath it. Sheet 11 is then fed by vacuum transport 50 into the opening created between a paddle 14 on top of stack 13 and the paddle retrained by indexing plate 20 with the lead edge of sheet 11 being driven under damper hook 18 and held in place by friction force. Paddle wheel assembly 10 is then rotated until damper hook 18 drags sheet 11 into registration wall 30 on top of paddle 14 that is on top of stack 13 and strips off the sheet as it passes behind the registration wall. The sheet is now registered to the registration wall and the damper hook 18 has moved off the sheet to allow side tamping by conventional means (not shown). Sheets already registered in the set are maintained in position up against registration wall 30 by the paddle 14 on top of the set providing normal force and friction force to hold the set in place. The side tampers close on the sheet/set to register sheets in the cross process direction. The sheet being compiled has the potential to drift away from the registration wall during tamping, however, this is addressed as the paddles 14 and scuffer 16 re-register the sheet to the registration wall as a last stage of the tamping operation. Once sheets are registered in the set, there is always normal and friction force from at least one paddle on top of the set, thereby eliminating a requirement for a trail edge tamper. That is, paddle wheel assembly 10 allows for the sheet being compiled to be scuffed upon entrance to compiler 8 and again at the end of tamping to maintain registration with the registration wall 30.
In recapitulation, a paddle wheel assembly 10 is disclosed that rotates while tampers are in the closed position and a paddle 14 that is being restrained on top of paddle indexing plate 20 drops down on top of sheet 11. A scuffer 16 is rotated by paddle wheel assembly 10 into contact with the now top sheet of stack 13 to register the sheet against registration wall 30. Continued rotation of paddle wheel assembly 10 strips the paddle 14 from between top sheet and the rest of the sheet set or main stack and side tampers are actuated to maintain cross process registration. Afterwards, the side tampers are opened and paddle wheel assembly parks with a damper hook 18 parked just before registration wall 30 to repeat the sheet registration process as a job requires.
The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others. Unless specifically recited in a claim, steps or components of claims should not be implied or imported from the specification or any other claims as to any particular order, number, position, size, shape, angle, color, or material.
