The present disclosure relates to sheet buffering systems, as would be used, for example, with printing and finishing (stapling, binding, etc.) apparatus.
In mid- to high-speed office equipment such as printers and copiers, the use of “finishers” is well known. A typical finishing module, which may be separable from or integral with the main portion of the printer, includes devices for compiling print sheets, such as forming a single multi-page document to be printed, and optionally stapling the compiled sheets. Other known finisher features include folding, hole-punching, booklet making, etc.
Many types of actions performed by a finisher require an appreciable amount of time to carry out on a single sheet or on a compiled set of sheets. In the context of a digital printer, however, sheets are ejected from the print engine and accepted by the finisher at a generally regular frequency: in the case of a 60 ppm (page per minute) print engine, a sheet is emitted every second; in a 120 ppm engine, a page is emitted every ½ second. A practical problem results when the finisher needs more time to perform an action than is permitted by the output of the engine. Thus, if a finisher requires ¾ of a second to perform a folding or stapling operation, an upstream engine operating at 120 ppm will emit a next sheet into the finisher while the finisher is performing the operation, probably resulting in a malfunction of the machine.
In the context of printing and finishing, a device called a “buffer” is used to temporarily withhold or retain one or more sheets emitted by the print engine from the finisher for a brief period of time so that the finisher can perform an action (such as stapling or folding) on one or more previously-emitted print sheets.
U.S. Pat. Nos. 5,303,017; 5,383,656; 5,951,004; and 6,332,606 show systems for temporarily retaining sheets in an area between a printing apparatus and a finisher.
According to one aspect, there is provided an apparatus comprising a baffle, suitable for passage of sheets in a process direction therethrough. A first gate and a second gate are disposed within the baffle in series along the process direction. Each of the first gate and second gate is positionable in an open position and a clamping position causing a sheet near the gate to be stopped.
According to another aspect, there is provided an apparatus comprising a baffle, suitable for passage of sheets in a process direction therethrough. A first gate is disposed within the baffle along the process direction. The first gate is positionable in an open position and a clamping position causing a sheet near the gate to be stopped. A sheet can pass relative to the first gate whether the first gate is in the open position or the clamping position.
As mentioned above, in some cases actions performed by the finisher (e.g., stapling sheets, and then ejecting the stapled set) require more time than is available before a further sheet is emitted from the printing apparatus, so that sheets emitted from the printing apparatus must be temporarily withheld from the finisher until the finisher is clear of previously-emitted sheets. To this end there is provided what can generally be called a “buffer” 10. The overall function of buffer 10 in this embodiment is to receive sheets from the printing apparatus, and as needed hold up to three sheets for a short period of time so that the sheets can then be moved, effectively simultaneously, toward the finisher.
In the illustrated embodiment, buffer 10 includes a baffle 12, which is basically a defined channel through which sheets can pass. The baffle 12 can be essentially an enclosed box, or can be defined by other structures. The baffle 12 includes therein three gates, indicated as 21, 22, 23, which are arranged in series along the process direction P through which a sheet would pass through baffle 12. Each gate is selectably positionable in an “open” position, allowing a sheet to pass relative thereto, and a “clamping” position, causing a sheet near the gate to be stopped. In the illustrated embodiment, the open position is consistent with the gate being up as shown, while the clamping position is consistent with the gate being down as shown. When the gate is in the down or clamping position, a surface of the gate is effectively urged against a contact surface (in the embodiment, the lower surface) defined by baffle 12. In the clamping position, a gate can thus clamp a sheet against the contact surface of the baffle 12, causing the sheet to stop any motion. However, when a gate is in the clamping position, a subsequent sheet passing through the baffle 12 can move past the gate.
In a practical embodiment, each gate 21, 22, 23 is independently positionable, and can be moved by any mechanical means (not shown), such as including a small motor, solenoid, plunger, etc. There may further be provided any number of mechanical, optoelectronic, or other sensors (not shown) to monitor positions of sheets within the buffer 10, as inputs to a control system.
Also as shown in
Each gate 21, 22, 23 may be provided with an effective surface of a predetermined frictional coefficient, to facilitate proper interaction with sheets being clamped therewith. Each gate may be dimensioned to contact a sheet through substantially the entire width thereof, or some portion or portions of the width. Although three gates are shown in the embodiment, two gates or more than three can be envisioned.
Although the illustrated series of actions results in the first sheet in the series S1 being clamped by the first gate in the series 21, and the other gates and sheets following in sequence, another possible implementation would have the first fed sheet S1 being clamped by the last gate 23, followed by sheets S2 clamped by gate 22 and sheet S3 clamped by gate 21. The reverse arrangement will result in a stack of sheets being conveyed out of baffle 12 that has sheet S1 leading the other sheets; this may be desirable depending on the architecture of the larger apparatus. Special shaping of functional surfaces on the gates or within the baffle may be required to implement this reverse arrangement.
The baffle 12 and its associated mechanisms may be provided within a stand-alone printing module (i.e., including a print engine such as including image receptor 100 shown in
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.