Document feeders

Abstract: Method and apparatus are disclosed for advancing two simplex documents (D) from an input stack to a copying platen, for making a desired number of duplex copies therefrom. A first simplex document is advanced to a registration position; a second simplex document is subsequently advanced to a registration position with respect to the first document; the documents thus registered are moved simultaneously to a copying position for sequential copying, and, subsequent to scanning the documents a desired number of times to produce a number of copies, are moved to an output.

Description: This invention relates generally to document feeders for duplex reproduction machines and more particularly to a document feeder suitable for placing two simplex documents on a copying machine simultaneously for copying. US-A-4,043,665 provides background information on document feeders; 4,179,215, 4,176,945, and 4,544,148 demonstrate use of sensors in the control of document feeders for placement of documents at copying positions; 3,869,202, 4,017,173, 4,052,054, 4,235,431, 3,635,555 and JP 60-2942 demonstrate two-up copying in a copier; and US-A- 4,468,114 and 4,579,444 demonstrate document handler control systems. US-A-4 610 446 also discloses these different aspects in combination in a copier. In increasingly complex reproduction or copier machines, customers demand an ever-increasing amount of options, while at the same time demanding lower cost and greater reliability. This is particularly true in the low copy volume copier market, where most copiers are sold. Until recently, small size has been achieved by leaving out features commonly found in larger, more-expensive, machines. Now, customers regularly demand the same features in smaller machines and at lower cost. Of particular interest in smaller copiers is the provision of duplex copying. Duplex copying, i.e. copying onto both sides of a single copy sheet, is a desirable feature for the reduction of quantities of paper, and the production of attractively reproduced materials. It is often possible and desirable to copy two documents (originals) having images only on a single side (simplex documents) onto both sides of a single copy sheet (duplex copy). This is sometimes accomplished in post-collation machines (machines having an copy sheet output into sorter bins, or without recirculating document handlers) by making a desired number of first-side (simplex) copies in a reproduction processor, passing the first-side copies to a duplex tray for temporary storage, and subsequently inverting and refeeding the first-side copies to the reproduction processor to receive second-side image information thereon. This function has also been accomplished by allowing two documents to be manually placed on a copying machine platen in side-by-side closely-spaced relationship (two-up), and sequentially scanning each document to produce copies thereof. The first-side copy sheets are inverted and returned immediately to the reproduction processor to receive second side copy thereon. Scanning of the documents to provide light images from each document on the platen, may be accomplished by either a scanning platen, as described in US-A- 4,017,173, or with scanning optics. Also described are arrangements for the return of copy sheets bearing first-side copy to receive second-side copy thereon. In accordance with the present invention, there is provided a method of operating a document feeder as claimed in claim 1 of the appended claims for feeding documents to be copied across the platen of a reproduction machine, particularly for advancing two documents onto the platen at the same time in spaced side-by-side relationship, whereby each document may be scanned separately to provide simplex to duplex copying. The present invention will now be described by way of example with reference to the accompanying drawings, in which: FIGURE 1 shows a somewhat-schematic view of the copy sheet and document paths as copy sheets and documents are passed through the processing stations of a reproduction machine, duplex module and document feeder; FIGURE 2 is a somewhat-schematic view of an automatic document handler in accordance with the present invention, and FIGURE 3 is a somewhat-schematic view of an recirculating document handler in accordance with the present invention. FIGURE 1 shows a small copier with which the present invention may have advantageous use. FIGURE 1 shows the paper and copy sheet paths and operational stations of a somewhat standard reproduction processor A, in conjunction with duplex module B, and document feeder C. The reproducing machine depicted in FIGURE 1 illustrates the various components utilized therein for presenting original documents and producing copies therefrom. The invention described herein is equally well suited for use in a wide variety of processing systems, including other reproduction systems of any size, and is not necessarily limited in application to the particular embodiment or embodiments shown herein. Reproduction processor A, illustrated in FIGURE 1, includes a belt photoreceptor member 14, the outer periphery of which is coated with a suitable photoconductive material. Belt 14 is mounted for movement about driven transport rolls 16 and 18, and travels in the direction indicated by the arrow on the inner run of the belt 14 to bring the image-bearing surface thereof past a plurality of conventional xerographic processing stations. Suitable drive means, such as motor 20, are provided to power and coordinate the motion of the various cooperating machine components, whereby a faithful reproduction of the original input image information is recorded upon copy sheets, such as of paper. Initially, photoreceptor 14 is passed through a charging station wherein photoreceptor 14 is uniformly charged with an electrostatic charge placed on the photoconductive surface by charge corotron 24 preparatory to imaging. Thereafter photoreceptor 14 is exposed to the light from the input image, whereby the charge is selectively dissipated in the exposed regions to record the input image in the form of electrostatic latent image. A document or documents D supported on platen 27 is scanned with a multi-mirror scanning optics system 28 schematically represented by the mirrors 30, 32, lamp 34 and lens 36 supported on carriages (not shown) and driven by servo motor 38, for controlled scanning movement. Multi-mirror scanning optics system 28 may typically be a four- or six-mirror arrangement of a type well known in the art, and providing controlled scanning of portions of platen 27 and accordingly, selectable scanning of documents placed thereon. Subsequent to imaging, the photoreceptor 14 passes through development station 40. A suitable development station could include a magnetic brush development system, including developer roll 42, utilizing a magnetizable developer mix having coarse magnetic carrier granules and toner colorant particles. Blank copy sheets, which may be of paper, plastics, etc. as desired, are supported in a stacked arrangement on elevated stack support tray 44. With the stack at its elevated position, the sheet separator segmented feed roll 46 feeds individual sheets therefrom to the registration pinch roll pair 48. Each sheet is then forwarded through nip roll pair 49 to transfer station 50 in proper registration with the image on the belt 14, and the developed image on the photoconductive surface is brought into contact with copy sheet within the transfer station 50, and the toner image is transferred from the photoconductive surface of the photoreceptor belt 14 to the contacting side of the copy sheet by means of transfer corotron 52. Following transfer of the image, the copy sheet is separated from photoreceptor 14 by the beam strength of the copy sheet as it passes around the curved face of photoreceptor 14 around the transport roller 18; and the copy sheet supporting the toner image thereon is advanced through fixing station 54 wherein the transferred powder image is affixed to the copy sheet by passing the copy sheet through heated fuser roller nip 56. After fusing the toner image to the copy sheet, it is advanced to the reversible exit nip 60 from where it may be directed to sheet stacking tray 62 or to the input of a sorter, or directed to duplex module B. Although a preponderance of toner is transferred to the copy sheet, invariably some residual toner remains on the photoconductive surface of photoreceptor belt 14 after the transfer of the toner image to the final support material or copy sheet. The residual toner particles remaining on the photoconductive surface after the transfer operation are removed from the belt 14 by the cleaning station 63, which comprises a cleaning blade 64 in scraping contact with the outer periphery of the belt 14, and contained within cleaning housing 66 which has a cleaning seal 68 associated with the upstream opening of the cleaning housing. Alternatively, the toner particles may be mechanically cleaned from the photoconductive surface by a cleaning brush. When the copier is operated in the manual mode, original documents D to be reproduced are placed on platen 27 and scanned by multi-mirror scanning optics 28 which direct light from the document to the photoreceptor 14 for copying. The speed of photoreceptor 14 and scanning optics 28 are synchronized to provide for accurate reproduction of the document. Platen 27 is preferably large enough to support at least two 216 x 280(8 1/2 x 11 inch) documents disposed on the platen, with their long edges adjacent, in spaced side-by-side relationship, and perpendicular to the plane of FIGURE 1. Servo motor 38 drives scanning optics 28 in its motion by platen 27 and is controllable by the reproduction processor controller 70 to scan platen 27 selectively, whereby only a portion of the platen or a selected document on the platen is copied. Additionally, while in normal copying operation, scanning optics 28 are moved along a path from a home position to a position required to complete exposure of a document to be copied, servo motor 38 is also controllable to provide repeated copying of such document, and returning scanning optics 28 to a "start scanning" position other than a normal home position for such copying. In this manner for example, a first portion of the platen supporting a first document may be scanned, and subsequently, the scanning optics may be moved to a second portion of the platen supporting a second document. Reproduction processor controller 70 is a programmable controller or combination of controllers, which conventionally controls all of the other machine steps and functions described herein, including the operation of the document feeder of the present invention, the paper path drives in both the reproduction processor A and duplex module B etc.. As further described herein, the controller 70 also conventionally provides for storage and comparisons of counted values including copy sheets and documents, and numbers of desired copies, and control of operations selected by an operator through alphanumeric display and control 72. Reversible exit nip 60 is provided with motor 74 for driving drive roller 76 in forward, reverse and stop motion. Motor 74 may advantageously be a stepper motor. Reproduction processor controller 70 instructs motor 74 to drive the drive roller 76 of exit nip 60 as required by the copying function in process. Thus, for simplex copying of a document, or completed duplex copying of a document, roller 76 is driven in a forward direction to drive copy sheet to output tray 62 thereby serving as an output driver. In the case where the copy sheet is required to receive a second-side image for a duplex copy, roller 76 is driven first in a forward direction until the copy sheet trail edge has cleared passive defector 78, and subsequently in reverse direction to drive the copy sheet back into reproduction processor A to be directed to the duplex module B. The process of changing direction while the copy sheet is in exit nip 60 serves to change the trail edge of the copy sheet to the lead edge to enable inversion of the document to receive a second-side copy. In certain cases, it will be desired to hold a copy sheet while the processor advances previously-returned copy sheets in order to time correctly the return of all the copy sheets to processor A for receiving a second image. In this case, roller 76 is stopped and the copy sheet is held between the rollers until a control signal is received from reproduction controller by the reversible exit nip motor 74, directing it to drive the paper in either forward or reverse motion Copy sheets to receive a second image thereon are passed downwardly from the passive deflector 78 along duplex module copy sheet path 80 to duplex module entry nip 82 which passes the copy sheet into the duplex module B. On passing duplex module entry nips 82, sheets are passed to duplex defector baffle 84 Duplex deflector baffle 84 serves to direct copy sheets to either trayless path 86 or duplex tray 88. As described below, when simplex to duplex copying with two documents on the platen is desired, the trayless path 86 is preferably used, for optimum efficiency of the copying operation. Documents directed to the trayless path are advanced through trayless path 86, driven by trayless path nip 90, to duplex module exit nip 92, which returns copy sheets from trayless path 86 in duplex module B to reproduction processor A. The copy sheets enter reproduction processor A at reproduction processor entry 94, and are directed to nip rolls 49. It will be appreciated that the now-inverted copy sheets are thereby returned to the original copy sheet path in reproduction processor A to receive second-side copy thereon. Referring now to FIGURE 2, which shows a document handler in accordance with the present invention, simplex documents to be copied to duplex copy sheets are stacked in input stack tray 100. When simplex to duplex style copying is selected by an operator at display 72, the feed control 102 is enabled. Feed control 102 is preferably a microprocessor controller, and may advantageously be comprised of an Intel Model 8051 controller, which will control operations of the document feeder in accordance with a series of predetermined steps. Documents in the input stack tray 100 may be stacked in a face-up order, with the first document in the set on top of the set and facing upwardly, for N to 1 document feeding. The last or Nth document of the set will be the lowermost document. The input stack tray 100 is advantageously provided with a bottom retard feeder 104, well known in the art, which feeds the Nth document out from the stack along document input path 106, while remaining documents in input stack tray 100 are held in place in the tray by stop 108 and normal force roller 110. As an alternative to an input stack tray, and within the scope of the invention, a document input may be provided for insertion of single documents in semi-automatic document feeding mode (SADF). A first document transport means is provided by locating a document feeder nip roll 112 driven by a first stepper motor 114 for engaging and advancing documents along the document input path. Document feeder nip roll set 112 advances documents through document input path 106 to a second document transport means comprised of wide friction belt platen transport 116 entrained about transport rolls 118 and 120 and driven by a second document feeder stepper motor 122. First and second document feeder stepper motors 114 and 122 may advantageously be comprised of a stepper motor providing 200 steps per motor revolution, in 1.8° increments The document feeder motors may both be driven by a common bipolar chopper drive (not shown) providing 1.5 amps per phase. Feed control 102 controls the chopper drive appropriately to operate the stepper motors. The document feeder stepper motors are controlled by a single drive to guarantee their synchronization. It will of course be appreciated that servo motors controlled in a similar manner would be acceptable for use in the document feeder. A document sensor 124 is provided along document input path 106 to detect the passage of selected edges of documents therepast. When sensor 124 detects, for example, a document passing thereby a signal is passed to the feed controller 102 indicating passage. The feed controller 102 will then provide control signals to first and second document feeder stepper motors 114 and 122 for a selected period to continue driving nip roll 112 and wide friction belt platen transport 116 to advance documents a corresponding distance to copying position. On completion of copying, the reproduction controller 70 signals the feed controller 102 to advance the documents to the output and recommence feeding from the bottom of the stack. When simplex to duplex copying, when placement of two documents on the platen is desired, operator selection of such operation is selected at the display 72. First document (N) is fed from the bottom of the stack of documents in input stack tray 100 by bottom retard feeder 104 to document input path 106. First document feeder stepper motor 114 is enabled to drive nip roll 112 advancing the first document to wide friction belt platen transport 116. As the trail edge of the first document passes by sensor 124, second document feeder stepper motor 122 is enabled to drive wide belt friction transport 116 for a first selected period to advance the trail edge of the first document a corresponding distance to a selected position, which may be conveniently about 10 mm beyond sensor 124. The first document may be stopped at this position, which provides at least a portion of the first document in driving engagement with wide belt friction transport 116. In the same manner, a second document (N - 1) is fed from the bottom of the stack of documents in input stack tray 100 by bottom retard feeder 104 to document input path 106. First document feeder stepper motor 114 is enabled to drive nip roll 112 advancing the second document to wide friction belt platen transport 116. As the lead edge of the second document is moved past sensor 124, the first document feeder stepper motor 114 continues to drive nip roll 112 advancing the second document for a second selected period of time to advance the lead edge of the second document a corresponding distance, to a registration position with respect to the first document, thereby placing the documents in side-by-side closely-spaced relationship a registration distance S apart. Second document feeder stepper motor 122 is then enabled to drive wide friction belt platen transport 116, advancing the registered documents to copying positions on platen 27 maintaining the registration distance S. In a preferred embodiment, two 216 x 280mm (8.5" x 11") documents fed long edge first (LEF) may be spaced less than approximately 2 mm apart. As previously described, the documents are sequentially scanned by multi-mirror scanning assembly 28. The documents are sequentially scanned by scanning the first document twice in succession, and subsequently scanning the second document twice in succession. During the period between first and second document scanning, copy sheets bearing first-side copy from the first document, are passed through fuser 54 to reversible exit nip 60 and reversed to trayless path 86 in duplex module B, from where the first-side copy sheets are returned to the reproduction processor A second-side up and disposed to receive copy from the second document. On receiving second-side copy on the second side of the copy sheet, the duplexed copy sheets are passed through reversible exit nip 60 to an output, such as for example, a sorter. On completion of scanning the documents a selected number of times corresponding to a desired number of copies, the first and second documents are removed from platen by enabling second document feeder stepper motor 122 to drive wide friction belt platen transport 116, advancing the closely-spaced documents to an output tray 126, through document output path 128. In an alternative control scheme, the speed of document feeding may be increased. Rather than stopping the second document at its registration position with respect to the first document, the fact that the second stepper motor 122 requires a brief acceleration period is used. Accordingly, after the first document has been advanced to its registration position past sensor 124, with a portion of the first document in driving engagement with wide belt friction transport 116, first document feeder stepper motor 114 drives nip roll 112 to advance the lead edge of the second document at a constant speed towards a registration position a distance S from the first document. When the lead edge of the second document passes sensor 124, second document feeder stepper motor 122 is enabled to drive wide friction belt platen transport 116, and accordingly, the first document. The second document continues advancing at a constant speed, which is greater than the speed of the accelerating first document. Before the first document has been accelerated to a final constant speed, the second document reaches a registration position with respect to the first document. The two documents continue advancing to copying positions on the platen 27, under the control of wide friction belt platen transport 116. In an alternative embodiment, as shown in FIGURE 3, a recirculating document handler is provided with the same capability of placing two documents in spaced side-by-side relationship at copying positions on platen. Recirculating document handlers are used in precollation reproduction machines, to successively feed a plural document set across a copying platen and provide a complete collated copy set corresponding to each time the document set is fed across the platen. Accordingly, no further sorting of the copy sets is required after the set is produced. In accordance with this embodiment an embodiment generally similar to that described with respect to FIGURE 2, is shown wherein the output means may include a nip roll set 150 to aid in the return of copied documents to document input tray 100 and the top of the original stack. For each set of copies desired, the plural document set is advanced through the document handler a corresponding number of times. It will be appreciated that recirculating document handlers, such as described in US-A- 4,468,114, are well known and may incorporate the described feeding and registration scheme of the present invention.

Claims: A method of operating a document feeder for advancing two simplex documents from an input stack (D) to adjacent positions on a reproduction machine to produce duplex copies therefrom, the document feeder including: an input stack feeder (104) for feeding documents from an input stack; two selectively-operable document transports (112, 116), with the second transport needing a period of known duration in which to accelerate a document from rest to a known constant speed; a sensor (124) positioned between the document transports for sensing the passage past it of the lead and trail edges of documents; a document transport controller (102) responsive to output signals from the sensor, and a document outlet, the method comprising: operating the input stack feeder to feed a first document from the input stack to the first document transport; operating each document transport until the first document is engaged by only the second transport and has come to rest with its trail edge at a chosen distance past the sensor; operating the stack feeder to feed a second document from the stack to the first transport; operating the first transport to advance the second document at a constant speed towards the stationary first document; when the second document has reached a predetermined position, as detected by the sensor, restarting the second transport to accelerate the first document from rest to a constant speed, at which time the second document has reached a position in which it is engaged by the second transport with its lead edge closely adjacent to the trail edge of the first document; stopping the second transport to bring both documents to predetermined adjacent copying positions, and restarting the second transport to drive both documents to the outlet. A method for recirculatively and precollatively copying a set of simplex documents on to both sides of copy sheets, to produce a desired number of precollated duplex copy sheets, using a document handler for feeding first and second simplex documents from an input stack (D) to adjacent copying positions on a reproduction machine; producing a first copy of the first document on a first side of a blank copy sheet, inverting the copy sheet to present a second side to the reproduction machine; producing a copy of the second document on the second side of the copy sheet, and returning the documents to the input stack, the document handler including: an input stack feeder for withdrawing documents from the stack in an N-to-1 order; two selectively-operable document transports (112,116), with the second transport needing a period of known duration in which to accelerate a document from rest to a known constant speed; a sensor (124) positioned between the document transports for sensing the passage past it of the lead and trail edges of documents; a document transport controller (102) responsive to output signals from the sensor, and a document feeder for returning documents to the input stack, the method comprising: operating the input stack feeder to feed a first document from the input stack to the first document transport; operating each document transport until the first document is engaged by only the second transport and has come to rest with its trail edge at a chosen distance past the sensor; operating the stack feeder to feed a second document from the stack to the first transport; operating the first transport to advance the second document at a constant speed towards the stationary first document; when the second document has reached a predetermined position, as detected by the sensor, restarting the second transport to accelerate the first document from rest to a constant speed, at which time the second document has reached a position in which it is engaged by the second transport with its lead edge closely adjacent to the trail edge of the first document; stopping the second transport to bring both documents to predetermined adjacent copying positions, and restarting the second transport to drive both documents to the document feeder. A method as claimed in claim 2, in which the document feeder is operated to feed the documents seriatim to the stack.

Inventors: DINATALE ERNEST LAWRENCE, PARTILLA STEPHEN RONALD, DINATALE, ERNEST LAWRENCE, PARTILLA, STEPHEN RONALD
Applicants: XEROX CORP, XEROX CORPORATION
Application year: 1987
Main classification: G03G15
IPC codes: B65H9, G03B27, B65H85, G03G15, B65H5, G03G21, B65H7, B65H83