Exit roller reversal gate for duplex printing

Abstract: In a reproduction apparatus outputting copy sheets via exit rollers (14) and stacking the outputted copy sheets adjacent the exit rollers in a stacking tray (18), and which exit rollers are reversible in their direction of rotation to feed selected copy sheets imaged on one side back into the reproduction apparatus in a return path to be reimaged, an actuatable gate system (30) prevents the previously outputted and stacking copy sheets from being recaptured by the reversed rotation exit rollers, by interposing a guide or baffle (32) between the stacking copy sheets and the exit rollers (14) to prevent accidental re-acquisition of copy sheets by the reversed rollers automatically in response to the reversal in direction of rotation of the exit rollers. The guide or baffle (32) preferably comprises commonly rotatably mounted arcuate fingers closely adjacent the exit rollers, which fingers are automatically rotated to extend outside of the periphery of the exit rollers towards the stacking tray in response to the reversal in direction of rotation of the exit rollers. That may be accomplished by camming this finger rotation from an axial shifting of the exit rollers also providing lateral deregistration.

Description: This invention relates to a sheet handling apparatus which is particularly, although not exclusively, useful in copiers or printers for printing copy sheets from optical or electronic page information utilizing reversible, dual mode, copy sheet rollers. There is disclosed herein an improvement in simple low cost duplexing or other second pass copying systems providing a simple integrated copy sheet output and optional copy sheet return path, such as that shown and described in US-A-4,708,462 noted below, or otherwise. The system disclosed herein is usable with various other types of duplexing or other second pass copying systems. These may be with trayless buffer loops, or with copy sheet stacking and refeeding from a buffer tray between the first and second copying (image transfer) operations, or a combination thereof. These systems are known in the published art. Of particular published art interest, as the herein-disclosed example of a duplexing path copier with a dual mode inverter/output path feeder system with reversing exit rolls, for a choice of simplex or duplex copying, with which the present invention may be effectively utilized as shown herein, is Xerox Corporation US-A-4,708,462 issued Nov. 24, 1987 to D. J. Stemmle, and art cited therein, (and also US-A-4,660,963 issued April 28, 1987 to D. J. Stemmle, and art cited therein). Other patent examples of duplexing copiers with duplexing paths including reversible sheet output rollers functioning as sheet inverters include Canon Sasaki et al US-A-4,787,616, and Ricoh Tsujihara US-A-4,692,020. [Said US-A-4,708,462 to D. J. Stemmle also discloses an optional path choice of a trayless duplex loop path extending over and bypassing a duplex buffer tray.] US-A-4,348,101 issued Sept. 7, 1982 to A. Schonfeld, et al (Sperry Corporation), shows a duplex laser printer with somewhat similar output and inverting paths. Reversing duplex printing operation is also shown in US-A-4,699,503 to Hyloft. Other references of background interest include Graef US-A-4,494,747 re selectively camming a fence 35 against a stack of sheets during a portion of the machine cycle in a currency dispenser to insure that the sheets are not picked up by the fed roll (see especially sheet 5 and Col. 7). To similar effect are Van Dalen US-A-3,108,801 and Binzoni et al US-A-3,173,684. Xerox Corp. US-A-4,493,483 to Teumer et al, and IBM TDB Vol. 20, No. 1, June 1977, page 22, by Bullock, show examples of a sheet reverser with a buckle control or kicker plate to insure feeding of a sheet being reversed into the correct nip. Examples of sheet lateral or side shifting or offsetting mechanisms are disclosed in US-A-4,712,786 and US-A-4,480,825. A helix and pin system therefore which is actuated by roller reversal for de-registration for duplex, like that disclosed herein, is disclosed in our copending European Patent Application published as EP-A-0 378 005 on July 18, 1990. With a sheet handling apparatus of the kind discussed in which sheet feed rollers feed sheets in a first direction into a receptacle such as a copy sheet output tray and in which the rollers may be reversed to return partially fed sheets to the machine for example for receiving a second, duplex, image, the problem may arise that on reversal of the rollers, sheets already in the output tray are re-acquired and unintentionally re-fed into the machine. The present invention is intended to prevent this problem, and accordingly provides sheet handling apparatus including sheet feed rollers for feeding sheets in a first direction into a receptacle, and means for driving said rollers in a first sense so as to feed sheets in the first direction, and in an opposite sense to return in the opposite direction sheets that have been partially fed between the rollers, characterised by baffle means mounted for movement between a first and a second position when sheets are being fed in the first and opposite directions respectively, the baffle means preventing sheets in said receptacle from being re-fed in said opposite direction by said rollers. A specific feature of the specific embodiment disclosed herein is to provide in a reproduction apparatus with means for outputting copy sheets via exit rollers and stacking the outputted copy sheets adjacent said exit rollers in a stacking tray, and which exit rollers are reversible in their direction of rotation to feed selected copy sheets imaged on one side back into said reproduction apparatus in a return path to be reimaged, the improvement comprising; actuatable gate means for preventing previously outputted and stacking copy sheets from being recaptured by said reversed rotation exit rollers by interposing guide or baffle means between the stacking copy sheets in said stacking tray and said exit rollers to prevent accidental re-acquisition of copy sheets by the reversed rollers, said actutable gate means including means for automatically interposing said guide or baffle means between the stacking copy sheets and said exit rollers in response to said reversal in direction of rotation of said exit rollers. Further specific features provided by the system disclosed herein, individually or in combination, include those wherein said guide or baffle means comprises arcuate fingers closely adjacent said exit rollers, which arcuate fingers are extended outside of the periphery of said exit rollers towards said stacking tray upon said actuation of said actuatable gate means in response to said reversal in direction of rotation of said exit rollers, wherein said guide or baffle means comprises commonly rotatably mounted arcuate fingers closely adjacent said exit rollers, which arcuate fingers are rotated to extend outside of the periphery of said exit rollers towards said stacking tray upon said actuation of said actuatable gate means in response to said reversal in direction of rotation of said exit rollers, and/or wherein said means for automatically interposing said guide or baffle means between the stacking copy sheets and said exit rollers in response to said reversal in direction of rotation of said exit rollers comprises camming means actuated by axial shifting of said exit rollers in response to said reversal in direction of rotation of said exit rollers. In particular, there is disclosed a system for automatically interposing guide or baffle means to prevent accidental re-acquisition of copy sheets previously fed from copy sheet rollers when the copy sheet feed rollers are reversed. This disclosed system for automatically interposing guide or baffle means to prevent accidental re-acquisition of copy sheets by the reversed rollers has particular utility with copy sheet exit rollers which eject copy sheets for adjacent copy sheet tray or sorter bin stacking but are reversible to return selected copy sheets into a duplex path with inversion for second side copying, or for second pass same side overprinting, such as for highlight color. The disclosed system automatically prevents previously ejected stacking copy sheets from being recaptured by the reversed rotation rollers, yet does not interfere with normal sheet feeding. Inadvertently pulling exited sheets back into the machine can cause paper jams, etc.. The specific disclosed embodiment can also effectively and efficiently utilize an existing axial (side-shifting) movement of the copy sheet exit rollers, serving another purpose, for the automatic interposing of the guide or baffle means. Various of the above-mentioned and further features and advantages will be apparent from the specific apparatus and its operation described in the example below, as well as the claims. Thus the present invention will be better understood from this description of an embodiment thereof, including the drawing figures (approximately to scale) wherein: Fig. 1 is a schematic side view of one example of a duplex copier incorporating the exit roller reversal gate system of the invention; Figs. 2 and 3 are otherwise identical perspective views of the exit roller reversal gate portion of the embodiment of Fig. 1, respectively showing the two operating positions of the exemplary exit roller gate mechanism, with respective movement arrows, but with the upper roller set not shown for drawing clarity; and Fig. 4 is an enlarged cross-sectional view of the copy sheet exit area of the embodiment of Figs. 1-3, including the exit roller reversal gate portion, with the two operating positions of the exit roller gate respectively shown in solid and phantom lines. With reference to the above-noted Figures, there is shown in Fig. 1 a duplex copier 10 by way of one example of an duplex electrostatographic reproducing machine of a type suitable to utilize the system of the present invention. While the machine 10 is exemplified here as an electrostatographic copier, other types of reproducing machines or apparatus such as laser or ink jet printers, etc., may be envisaged. Although the present system is particularly well adapted for use in such compact copiers or printers, it will be evident from the following description that it is equally well suited for use in a wide variety of reproduction systems and is not limited in application to the particular embodiment shown herein. The Fig. 1 illustrated duplex copier 10 per se is that shown and described in the above-cited US-A-4,708,462, and elsewhere, and thus need not be redescribed herein. Thus, the following description relates only to the subject copy sheet output path portion 12 of the copier 10, shown in more detail in Fig. 4 and Figs. 2 & 3. The subject copy sheet output path portion 12 particularly includes two mating or nipped sets of copy sheet output path rollers 14. The rollers 14 comprise a lower set of rollers 14b on an axially movable as well as rotatable shaft 15, and upper rollers 14a. One said set of the rollers 14 are selectably reversibly driven by a reversible drive 16. The other roller set may, conventionally, be idlers. The rollers 14 normally continue rotating in one direction to feed and drive the sheets downstream to eject the sheets out of this exit nip to be stacked into output tray 18 (a fixed single tray or or a selected sorter bin), as shown in more detail in Fig. 4. However, for duplexing copy sheets, the rollers 14 are reversed while a copy sheet only printed on its first side is still in the roller 14 nip, to transport those copy sheets back into a duplex path 20, for returning those copy sheets to the copy processor with inversion be imaged on their opposite sides to make duplex copies, as shown in Fig. 1. This is taught by the above-cited and other references, particularly the US-A-4,708,462 embodiment disclosed here. To summarize, the sheet reversing for inverting function is integral with the normal exit transport and paper path, implemented by reversal of rollers 14 and thus reversal of a sheet in the nip thereof. When output of a simplex or fully duplexed copy sheet is desired, the rollers 14 simply continue to rotate in the same forward or downstream feeding direction until the sheet is fully ejected from the rollers nip, instead of reversing after only part of the sheet is extending therefrom. Turning now to the disclosed system 30 for automatically interposing guide or baffle means to prevent accidental re-acquisition of copy sheets be the reversed rollers 14, this is embodied here by arcuate guide or baffle fingers 32 mounted to pivotal shaft 34 located closely adjacent, slightly under, and parallel to, shaft 15 of the lower set of rollers 14b. The fingers 32 are normally spring loaded by torsion spring 36 into the "up" or first position shown in Fig. 2 (and also shown in phantom or dashed lines in Fig. 4) for normal downstream or forward sheet feeding for ejection and stacking. In this first operating position the arcuate guide or baffle fingers 32 are substantially inside the radius of the lower set of rollers 14b, out of normal sheet engagement. This disclosed embodiment utilizes an exiting axial (side-shifting) movement of the copy sheet exit rollers 14, serving another purpose, for actuating the automatic interposing of the guide or baffle system 30 to prevent accidental re-acquisition of copy sheets previously fed from the rollers 14 when the rollers 14 are reversed. This second operating position of the guide or baffle fingers 32 is shown in Fig. 3 and also shown in solid lines in Fig. 4. As particularly shown in Fig. 4, in this second operating position of the fingers 32 they are substantially extended outside of the radius of the lower set of rollers 14b, downward and forward, to push away and hold away the rear edges of previously ejected sheets from the lower rollers 14b, and thus providing an active gate to prevent those sheets already in the exit tray 18 area from being engaged, picked up and fed back into the nip of rollers 14. That is a particular problem with copy sheets with fluff or curl, which tends to cause their rear edges to engage the rollers 14b, the surfaces of which are moving upwardly and into the nip when the rollers 14 are reversed. With the system 30, at least one gate finger 32 is closely operatively associated with each roller 14b, moving outside of the roller profile when the roller is reversed to shield it. As shown particularly in Fig. 3, shaft 15 automatically shifts axially (see the movement arrow) when the reversible drive 16 reverses the direction of drive rotation. This may be accomplished by a helical coupling 40, or various other conventional, cam or side-shifting mechanisms. As noted above, a similar helix and pin system actuated by roller reversal is disclosed in copending EP-A-0 378 005. There it is shown shifting the individual rollers, but the same mechanism may be used here at one end of the shaft 15 to shift the shaft 15. Other above-noted examples of sheet lateral (side) shifting or offsetting mechanisms are disclosed in US-A-4,712,786 and US-A-4,480,825. When the rotation of the shaft 15 is reversed, the helical coupling 40 translates or pulls the shaft 15. A camming roller 42 on shaft 15 engages an inclined plane cam follower 44 attached to pivotal shaft 36. Thus the axial shifting of shaft 15 and camming roller 42 thereon forces down cam follower 44 which causes a corresponding rotation of shaft 34 and the attached guide or baffle fingers 32 into the second operating position. This occurs automatically in response to the axial movement of the roller 14 system. That axial movement of the reversible roller 14 system is provided for an additional reason and function other than the actuation of gate system 30. It also provides a de-registration system for duplexing, as per the above-noted copending application. It side-shifts by a small distance (e.g., 3 to 3.5 mm) those copy sheets being reverse fed back into the duplex path 20 so that those sheets may be fed through the duplex path 20 without edge drag, and so that they can subsequently be re-side-registered for the second pass image by side sifting them back in one (known) direction of movement, irrespective of slight misregistrations or skewing in the duplex return path. As is well known in the art, to control the operation of the machine 10 a suitable programmable controller 100 and a connecting control panel is preferably conventionally provided. Conventional and/or programmable software microprocessor controls may be used for controlling all machine and paper operations and sensing. While the embodiment disclosed herein is preferred, it will be appreciated from this teaching that various alternatives, modifications, variations or improvements therein may be made by those skilled in the art, which are intended to be encompassed by the following claims.

Claims: Sheet handling apparatus including sheet feed rollers (14) for feeding sheets in a first direction into a receptacle (18), and means for driving said rollers in a first sense so as to feed sheets in the first direction, and in an opposite sense to return in the opposite direction sheets that have been partially fed between the rollers, characterised by baffle means (32) mounted for movement between a first and a second position when sheets are being fed in the first and opposite directions respectively, the baffle means preventing sheets in said receptacle from being re-fed in said opposite direction by said rollers. The apparatus of claim 1 wherein the baffle means (32) prevents said sheets in said receptacle from being re-fed in said second position. The apparatus of claims 1 or claim 2 wherein the baffle means (32) is mounted for said movement in response to the sense of rotation of said rollers (14). The apparatus of any one of claims 1 to 3, wherein said baffle means comprises arcuate fingers (32) closely adjacent said rollers (14), which arcuate fingers are extended outside of the periphery of said rollers towards said receptacle when the baffle means is in said second position. The apparatus of claim 4, wherein said arcuate fingers (32) are commonly rotatably mounted (34). The apparatus of any one of claims 1 to 5, including means (36, 42, 44) for automatically moving said baffle means (32) to its second position, comprising camming means (44) actuated by axial shifting of said rollers in response to said reversal in direction of rotation of said rollers. A reproduction apparatus (10) including a sheet handling apparatus (12) for outputting copy sheets via exit rollers (14) and stacking the outputted copy sheets adjacent said exit rollers in a stacking tray (18), and which exit rollers are reversible in their direction of rotation to feed selected copy sheets imaged on one side-back into said reproduction apparatus in a return path (20) to be reimaged, the sheet handling apparatus being an apparatus according to any one of claims 1-6, wherein said rollers comprise the exit rollers and said receptacle comprises the stacking tray.

Inventors: DE VITO GERALD M, DE VITO, GERALD M.
Applicants: XEROX CORP, XEROX CORPORATION
Application year: 1990
Main classification: G03G15
IPC codes: B65H29, B65H3, B65H31, G03G15