JP2010060822A - Image forming apparatus, image forming system, program, and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming system that has high job efficiency without delaying the subsequent supply of sheet of paper in order to obtain a longer post-processing for the previous set of sheets of paper when executing a plurality of double-sided image formation jobs. <P>SOLUTION: As a result of determinations made by a condition determining section, a paper feed delay necessity determining section, and a retraction allowance determining section, paper P4 is guided and evacuated to a right side paper ejection conveyance path 39, the paper P4 being a first sheet of paper of a second set of sheets of paper subjected to image formation on both its sides and conveyed to a first paper ejection roller 34 via a first paper conveying path 31. On the other hand, paper P5 is evacuated to a double-sided conveyance path 36, the paper P5 being a second sheet of paper of a second set of sheets of paper subjected to image formation on both its sides and conveyed to the first paper ejection roller via the first paper conveyance path 31. These first and the second sheets of paper P4 and P5 are superposed on paper P6, and these three sheets can be simultaneously ejected, the paper P6 being the third sheet of paper of the second set of sheets of paper ejected to a post-processing device by the first paper ejection roller 34 via the first paper conveyance path 31 after image formation on both the sides. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique for improving the productivity of an image forming system in which a post-processing apparatus is attached to an image forming apparatus.

  Some image forming apparatuses can optionally be connected to a post-processing apparatus that performs post-processing on paper discharged from the image forming apparatus. An image forming system is configured by attaching a post-processing device to the image forming apparatus. Post-processing includes stapling the paper, discharging the paper to a designated paper discharge tray among a plurality of paper discharge trays, and offsetting the discharge position on the paper discharge tray.

  In Patent Document 1, in such an image forming system, the image forming apparatus starts a second image forming job (next part) without waiting for completion of post-processing change preparation by the post-processing apparatus. A configuration is disclosed in which the post-processing apparatus starts post-processing of the second image forming job as soon as preparation for changing the post-processing is completed.

  That is, after the first image forming job (the image forming job immediately before the second image forming job: the previous part) is terminated, the image forming apparatus prepares to change the post-processing. The paper feeding / conveyance is resumed at an appropriate timing before completion, and the paper is supplied to the post-processing apparatus at almost the same timing as preparation for changing the post-processing is completed.

In this way, the time required from the start of the first image forming job to the end of the post-processing of the second image forming job can be shorter than before.
Japanese Patent Laying-Open No. 2005-321482 (published on November 17, 2005)

  However, in the configuration of Patent Document 1 described above, even when the image forming apparatus is able to avoid the problem that the image forming apparatus waits while the post processing apparatus needs to prepare for changing the post process, the image forming job is performed continuously. When a plurality of image forming jobs requiring post-processing are continuously performed, the image forming apparatus waits with a delay in the start of the next unit in order to earn post-processing time for the previous unit. It is not possible to solve the decrease in job efficiency due to the above.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to ensure the post-processing time of the previous part in order to ensure the post-processing time of the previous part in continuously executing continuous image forming jobs. Image forming apparatus and image capable of improving productivity without delaying image formation or shortening the time as much as possible even if delay is necessary, without wasting performance of the image forming apparatus It is to provide a forming system.

  In order to solve the above problems, an image forming apparatus according to the present invention includes a paper feeding unit in which paper is stored, an image forming unit that forms an image on the paper, and a paper on which image formation has been performed in the image forming unit. A first discharge section that discharges to the outside, a main transport path that guides the sheet from the paper feed section to the first discharge section via the image forming section, and the image from upstream of the first discharge section in the main transport path A first sub-conveying path that guides the sheet on which image formation has been completed on one surface to the upstream side of the forming unit, and a second unit that guides the sheet from the upstream side of the first discharging unit in the main transporting path to another second discharging unit. In an image forming apparatus that includes two sub-conveying paths and that is provided with a post-processing device that performs post-processing on the paper discharged from the first discharge unit, the image forming conditions are as follows. For double-sided image formation that forms images on both sides, and for configuring one part Condition judging means for judging whether or not the number of copies is 3 or more and whether the number of copies is 2 or more, and feeding of the next set of sheets for the post-processing of the previous set discharged in the transport plan. The paper feed delay necessity judgment means for judging whether or not the paper needs to be delayed and the condition judgment means are used for double-sided image formation, wherein the number of sheets per copy is three or more and the number of copies is two or more. When it is determined that there is a need to delay paper feeding by the paper feed delay necessity judging means, the paper transport mechanism in the main transport path and the second sub transport path is controlled. Then, the first sheet of the next portion that is transported and discharged to the first discharge section through the main transport path is guided from the first discharge section to the second sub-transport path and temporarily retracted. The retracted first sheet is then transported to the first discharge section via the main transport path. It is characterized in that the overlapping sheet discharge control means for two discharging simultaneously superimposed with the second sheet of the next part is provided to be discharged Te.

  According to this, the condition determination means is such that the image forming condition is double-sided image formation in which images are formed on both sides of the sheet, and the number of sheets constituting one copy is three or more and the number of copies is two or more. Whether the paper feed delay necessity judging means needs to delay paper feeding of the next part in order to perform post-processing of the previous part that was previously ejected in the transportation plan. to decide.

  Then, it is determined by the condition determining means that double-sided image formation is being performed, and the number of sheets per copy is 3 or more and the number of copies is 2 or more. When it is determined that it is necessary to delay the paper feeding, the overlap paper discharge control unit controls the paper transport mechanism in the main transport path and the second sub transport path and transports it to the first discharge section via the main transport path. Then, the first sheet of the next portion to be discharged is guided from the first discharge portion to the second sub-transport path and temporarily retracted, and the retracted first sheet is then passed through the main transport path. Then, the two sheets are superposed on the second sheet of the next section to be conveyed and discharged to the first discharge section and discharged simultaneously.

  By discharging two sheets at the same time, the timing at which the first sheet of the next section is discharged to the post-processing device can be delayed by up to three sheets on one side. If it is within the time for three sheets, it is possible to continuously perform the next section without delaying the feeding timing of the next sheet. Further, even if the post-processing time exceeds the time for three sheets on one side, the time for delaying the sheet feeding timing of the next sheet can be shortened.

In order to solve the above problems, an image forming apparatus according to the present invention includes a paper feeding unit in which paper is stored, an image forming unit that forms an image on the paper, and a paper on which image formation has been performed in the image forming unit. A first discharge section that discharges to the outside, a main transport path that guides the sheet from the paper feed section to the first discharge section via the image forming section, and the image from upstream of the first discharge section in the main transport path A first sub-conveying path that guides the sheet on which image formation has been completed on one side to the upstream side of the forming unit, and a second unit that guides the sheet from the upstream side of the first discharging unit in the main transport path to another second discharging unit. In an image forming apparatus that includes two sub-conveying paths and that is provided with a post-processing device that performs post-processing on the paper discharged from the first discharge unit, the image forming conditions are as follows. For double-sided image formation that forms images on both sides, and for configuring one part Condition judging means for judging whether or not the number of copies is 3 or more and whether the number of copies is 2 or more, and feeding of the next set of sheets for the post-processing of the previous set discharged in the transport plan. A paper feed delay necessity judging means for judging whether the paper needs to be delayed,
An evacuation possibility judging means for judging whether or not the sheet can be evacuated to the first sub-conveying path in the conveyance plan;
The condition determination means determines that double-sided image formation is performed, and the number of sheets per copy is 3 or more and the number of copies is 2 or more. When it is determined that it is necessary to delay the sheet feeding, and the retractability determination unit determines that the sheet can be retracted, the main transport path, the first sub transport path, and the second sub transport path By controlling the paper transport mechanism, the first sheet of the next part that is transported and discharged to the first discharge part via the main transport path is discharged from the first discharge part to the second sub-transport path. The second sheet of the next part to be transported and discharged to the first discharge part through the main transport path and then discharged from the first discharge part to the first sub-transport. The first sheet and the second sheet that have been retracted are led to the path and retracted through the main transport path. And overlaid paper discharge control means for three discharging simultaneously superimposed with the third sheet of the next parts to be discharged is conveyed serial to the first discharge unit is characterized by being provided.

  According to this, the condition determination means is such that the image forming condition is double-sided image formation in which images are formed on both sides of the sheet, and the number of sheets constituting one copy is three or more and the number of copies is two or more. Whether the paper feed delay necessity judging means needs to delay paper feeding of the next part in order to perform post-processing of the previous part that was previously ejected in the transportation plan. to decide. Further, the retractability determination unit determines whether the sheet can be retracted to the first sub-transport path in the transport plan.

  Then, it is determined by the condition determining means that double-sided image formation is being performed, and the number of sheets per copy is 3 or more and the number of copies is 2 or more. If it is determined that it is necessary to delay the sheet feeding, and the evacuation enable / disable determining unit determines that the sheet can be evacuated, the overlapped sheet discharge control unit performs the main conveyance path, the first sub conveyance path, and the second sub conveyance path. By controlling the paper transport mechanism in the transport path, the first sheet of the next part that is transported and discharged to the first discharge section via the main transport path is transferred from the first discharge section to the second sub-transport path. While being guided and retracted, the second sheet of the next part, which is then transported to the first discharge section via the main transport path and discharged, is guided from the first discharge section to the first sub transport path to be retracted. The retracted first and second sheets are transported to the first discharge section via the main transport path and discharged. Superimposed with the third sheet parts 3 sheets is discharged simultaneously.

  By simultaneously discharging three sheets, the timing at which the first sheet of the next section is discharged to the post-processing device can be delayed by up to four sheets on one side, so the post-processing time can be reduced If it is within the time for four sheets, it is possible to continuously perform the previous section without delaying the feeding timing of the next sheet. Further, even if the post-processing time exceeds the time for four sheets on one side, the time for delaying the feeding timing of the next sheet can be shortened.

  In the configuration in which two sheets are retracted using the first sub-transport path and the second sub-transport path, the first sub-transport path and the second sub-transport path are upstream of the first discharge unit. It is preferable that the route is partially shared.

    By sharing a part of the path of the first sub-transport path and the second sub-transport path on the upstream side of the first discharge unit, the two sheets that have been evacuated are overlapped first in this shared part. Since the sheets can be aligned, the leading edges can be aligned more easily than when the sheets are conveyed from three directions and stacked three at a time.

  Furthermore, it is preferable that the image forming apparatus of the present invention includes an image order adjusting unit that adjusts the image forming order in consideration of the stacking order of a plurality of sheets to be discharged in a superimposed manner.

  When a plurality of sheets are stacked and discharged at the same time, the main transport path, the first sub-transport path, or the second sub-transport path is arranged so that the stacking order is the same as that of the sheets ejected one by one. This reduces the degree of design freedom. Therefore, in the above configuration, the image order adjusting unit adjusts the image forming order in consideration of the stacking order of the plurality of sheets to be discharged in a superimposed manner.

  As a result, even if the first sheet is stacked on the second sheet and ejected face-down, the image formation order is changed to the second page, the second page, and the second page. By adjusting so that the image of the first page is formed in the eye, the page order can be obtained in the same manner as in the case where the sheets are discharged one by one.

  In order to solve the above-described problems, an image forming system according to the present invention includes a paper feeding unit that stores paper, an image forming unit that forms an image on the paper, and a paper on which image formation has been performed in the image forming unit. A first discharge section that discharges to the outside, a main transport path that guides the sheet from the paper feed section to the first discharge section via the image forming section, and the image from upstream of the first discharge section in the main transport path A first sub-conveying path that guides the sheet on which image formation has been completed on one surface to the upstream side of the forming unit, and a second unit that guides the sheet from the upstream side of the first discharging unit in the main transporting path to another second discharging unit. In an image forming system including an image forming apparatus including two sub-transport paths and a post-processing apparatus that performs post-processing on the paper discharged from the first discharge unit, the image forming condition is that images are formed on both sides of the paper. Double-sided image formation to be formed, and the number of sheets constituting one copy is 3 The condition determination means for determining whether or not the number of copies is two or more, and the paper feeding of the next copy is required to be delayed in order to perform post-processing of the previous copy that has been discharged first in the transport plan. In the paper feed delay necessity judgment means for judging whether or not there is a paper sheet and the condition judgment means, it is judged that double-sided image formation is performed and the number of sheets per copy is 3 or more and the number of copies is 2 or more. And when the paper feed delay necessity judging means judges that the paper feed needs to be delayed, the paper transport mechanism in the main transport path and the second sub transport path is controlled, The first sheet of the next portion that is transported and discharged to the first discharge section via the main transport path is guided from the first discharge section to the second sub transport path to be temporarily retracted and retracted. The first sheet is then transported to the first discharge section via the main transport path and discharged. And overlaid paper discharge control means to which the superposed with the second sheet of the next section to discharge two simultaneously is characterized in that provided that.

  As already described as the image forming apparatus, it is possible to realize an image forming system with high productivity without wasting performance of the image forming apparatus.

  In order to solve the above-described problems, an image forming system according to the present invention includes a paper feeding unit that stores paper, an image forming unit that forms an image on the paper, and a paper on which image formation has been performed in the image forming unit. A first discharge section that discharges to the outside, a main transport path that guides the sheet from the paper feed section to the first discharge section via the image forming section, and the image from upstream of the first discharge section in the main transport path A first sub-conveying path that guides the sheet on which image formation has been completed on one surface to the upstream side of the forming unit, and a second unit that guides the sheet from the upstream side of the first discharging unit in the main transporting path to another second discharging unit. In an image forming system including an image forming apparatus including two sub-transport paths and a post-processing apparatus that performs post-processing on the paper discharged from the first discharge unit, the image forming condition is that images are formed on both sides of the paper. Double-sided image formation to be formed, and the number of sheets constituting one copy is 3 The condition determination means for determining whether or not the number of copies is two or more, and the paper feeding of the next copy is required to be delayed in order to perform post-processing of the previous copy that has been discharged first in the transport plan. A paper feed delay necessity judging means for judging whether or not there is, a retractability judging means for judging whether or not a sheet can be retracted to the first sub transport path in the transport plan, and the condition judging means. Thus, it is determined that double-sided image formation is performed and that the number of sheets per copy is 3 or more and the number of copies is 2 or more, and the paper feed delay necessity determination means needs to delay paper feed. And when the retractability determination means determines that the sheet can be retracted, the sheet transport mechanism in the main transport path, the first sub transport path, and the second sub transport path is controlled. And conveyed to the first discharge unit via the main conveyance path and discharged. The first sheet of the next part is led from the first discharge part to the second sub-conveying path and then retracted, and then conveyed to the first discharging part via the main conveying path and discharged. The second sheet of the next part is led from the first discharge section to the first sub-transport path and retracted, and the retracted first and second sheets are moved along the main transport path. And a superposition discharge control means for superimposing a third sheet of the next portion that is conveyed and discharged to the first discharge portion, and simultaneously discharging three sheets.

  As already described as the image forming apparatus, it is possible to realize an image forming system with high productivity without wasting performance of the image forming apparatus.

  Further, according to the present invention, there is provided a program for causing a computer to function as a waiting time generation determination unit, a single-sided image formation determination unit, an overlap sheet discharge control unit, and an image order adjustment unit in the above-described image forming apparatus of the present invention. The category is a computer-readable recording medium on which the program is recorded.

  That is, in the image forming apparatus, the condition determination unit, the paper feed delay necessity determination unit, the evacuation possibility determination unit, the overlap discharge control unit, and the image order adjustment unit may be realized by hardware or a program. You may implement | achieve by making a computer perform. Specifically, the program according to the present invention is a program that causes a computer to operate as each of the above-described units, and the program is recorded on a recording medium according to the present invention.

  When these programs are executed by a computer, the computer serves as a condition determination unit, a paper feed delay necessity determination unit, a retractability determination unit, an overlap discharge control unit, and an image order adjustment unit in the image forming apparatus. Operate. Therefore, the image forming apparatus has the same effects as the condition determination unit, the paper feed delay necessity determination unit, the evacuation possibility determination unit, the overlap sheet discharge control unit, and the image order adjustment unit.

  As a result, it is possible to realize an image forming system with high productivity without wasting performance of the image forming apparatus.

  An embodiment of the present invention will be described below with reference to FIGS.

  First, the configuration of the image forming system 1 according to an embodiment of the present invention will be described with reference to FIG. FIG. 2 is an explanatory diagram showing the configuration of the image forming system 1.

  The image forming system 1 is configured by adding an after-processing device 3 and two paper feeding devices 4 and 5 to an image forming device 2. Here, a configuration in which two paper feeding devices 4 and 5 are attached together with the post-processing device 3 is illustrated, but as an image forming system in the present invention, at least a post-processing device is attached to the image forming device. It only has to be.

  The image forming apparatus 2 selectively performs multicolor and single color image formation by electrophotography based on image information input via a network or the like, and records the formed image on a sheet. The image forming apparatus 2 includes an image forming unit 6, a paper storage unit 7, and a paper transport unit 8.

  The image forming unit 6 includes an exposure unit 10, an intermediate transfer belt 11, and a secondary transfer roller 14. The image forming stations 12A to 12D are arranged in a line between the intermediate transfer belt 11 and the exposure unit 10. ing.

  Each of the image forming stations 12 </ b> A to 12 </ b> D forms an image based on image information of each hue of a total of four colors obtained by adding black to cyan, magenta, and yellow, which are three subtractive primary colors obtained by color separation of a color image. I do.

  The black image forming station 12A includes a photosensitive drum 101A, a developing unit 102A, a charging roller 103, a primary transfer roller 104, a cleaning unit 105, and the like.

  The charging roller 103 is a contact-type charger that uniformly charges the surface of the photosensitive drum 101A to a predetermined potential. Instead of the charging roller 103, a contact-type charger using a charging brush or a contact-type charger using a charging charger can be used. The exposure unit 10 includes a light source such as a semiconductor laser, a polygon mirror, a reflection mirror, and the like. The photosensitive drum 101A is irradiated with image light based on the black image information from the exposure unit 10, and an electrostatic latent image corresponding to the image information of the black hue is formed.

  The developing unit 102A supplies black toner to the surface of the photosensitive drum 101A on which the electrostatic latent image is formed, and develops the electrostatic latent image into a toner image. The cleaning unit 104 collects toner remaining on the surface of the photosensitive drum 101A.

  The intermediate transfer belt 11 forms a loop-shaped movement path. The intermediate transfer belt 11 passes between the photosensitive drum 101A and the primary transfer roller 104 in the lower movement path.

  A primary transfer bias having a polarity opposite to the toner charging polarity is applied to the primary transfer roller 104 by constant voltage control, and the toner image formed on the photosensitive drum 101 </ b> A is transferred to the outer peripheral surface of the intermediate transfer belt 11.

  Each of the image forming stations 12B, 12C, and 12D for each hue of cyan, magenta, and yellow is configured in the same manner as the image forming station 12A. However, the image forming stations 12B, 12C, and 12D are irradiated from the exposure unit 10 with image light modulated by image information of each hue of cyan, magenta, and yellow. Each of the developing units 102B, 102C, and 102D supplies toners of cyan, magenta, and yellow hues to the photosensitive drums 101B, 101C, and 101D.

  As a result, toner images of hues of cyan, magenta, and yellow are formed on the photosensitive drums 101B, 101C, and 101D, respectively.

  When image information of only a part of the hues of yellow, magenta, cyan and black is input, one of the four image forming stations 12A, 12B, 12C and 12D corresponding to the hue of the input image information. The electrostatic latent image and the toner image are formed only in the portion. For example, during monochrome image formation, an electrostatic latent image and a toner image are formed only in the black image forming station 12A, and only the black developer image is transferred to the outer peripheral surface of the intermediate transfer belt 11.

  At the time of full-color image formation, electrostatic latent image formation and toner image formation are performed in all of the four image forming stations 12A, 12B, 12C, and 12D. Yellow, magenta, cyan, and black toner images are sequentially superimposed and transferred onto the outer peripheral surface of the intermediate transfer belt 11.

  Transfer of the toner image to the outer peripheral surface of the intermediate transfer belt 11 corresponds to image preparation in the image forming unit 6 of the present invention.

  The toner image transferred to the outer peripheral surface of the intermediate transfer belt 11 is conveyed to a position facing the secondary transfer roller 14 by the rotation of the intermediate transfer belt 11. The secondary transfer roller 14 is in pressure contact with the outer peripheral surface of the intermediate transfer belt 11 with a predetermined nip pressure. A position where the intermediate transfer belt 11 and the secondary transfer roller 14 face each other is an image forming position 30 where an image is formed on a sheet.

  The paper storage unit 7 includes paper feed cassettes 16 </ b> A and 16 </ b> B and a manual feed tray 17, each of which stores a plurality of sheets of a single type. Further, the image forming apparatus 2 is optionally provided with paper feeding devices 4 and 5 as external paper storage units.

  The sheet feeding device 4 is disposed below the image forming apparatus 2 and includes sheet feeding cassettes 16C and 16D. The sheet feeding device 5 is disposed on the side surface of the image forming apparatus 2 and stores a large number of single-type sheets.

  In the paper transport unit 8, a first paper transport path 31 is formed from the paper feed cassettes 16 </ b> A and 16 </ b> B via the image forming position 30 to the post-processing device 3 installed on the upper surface of the image forming apparatus 2. In the first paper transport path 31, pickup rollers 21A and 21B, paper feed rollers 22A and 22B, a registration roller 32, a fixing unit 33, a fourth transport roller 87, a first paper discharge roller 34, and the like are arranged.

  Further, a second paper transport path 35 that connects the manual feed tray 17 to the upstream side of the registration roller 32 in the paper transport direction of the first paper transport path 31 is formed in the paper transport unit 8.

  Further, the sheet conveying unit 8 is connected to the upstream side of the registration roller 32 in the sheet conveying direction of the first sheet conveying path 31 between the fixing unit 33 and the first paper discharge roller 34 in the first sheet conveying path 31. A double-sided transport path (first sub-transport path) 36 and a right-side paper discharge transport path (second sub-transport path) 39 communicating with the right-side paper discharge tray 72 via the second paper discharge roller 84 are formed. Yes. Among these, the double-sided conveyance path 36 is for carrying a single-sided image-formed sheet that is switchback-conveyed by reversal of the first paper discharge roller 34 when a double-sided image is formed on both sides of the sheet.

  In addition, a third paper transport path 37 that connects the paper feeding device 5 to the first paper transport path 31 is also formed in the paper transport unit 8. The paper feeding cassettes 16 </ b> C and 16 </ b> D in the paper feeding device 4 are communicated with the first paper feeding path 31 through a fourth paper feeding path 38 provided in the paper feeding device 4. Note that. A more detailed configuration of the paper transport unit 8 will be described later with reference to FIG.

  The sheets supplied from the sheet storage unit 7 and the sheet feeding devices 4 and 5 are conveyed through the first sheet conveyance path 31 and receive the transfer of the toner image from the intermediate transfer belt 11 when passing the image forming position 30. . Further, at the time of double-sided image formation, the sheet on which the toner image has been transferred is switchback conveyed by the reverse of the first paper discharge roller, and is conveyed again to the first sheet conveying path 31 via the double-sided conveying path 36. When passing through the image forming position 30, the toner image is transferred from the intermediate transfer belt 11 to the other surface.

  The registration rollers 32 arranged in the first paper transport path 31 are transported from the paper storage unit 7 (paper feed cassettes 16 </ b> A and 16 </ b> B, manual feed tray 17), the paper feeder 4, the paper feeder 5, or the double-sided transport path 36. The rotation is stopped when the leading edge of the sheet reaches.

  The registration roller 32 rotates at the timing when the leading edge of the toner image adhering to the intermediate transfer belt 11 reaches the image forming position 30 when the leading edge of the paper that has passed the registration roller 32 reaches the image forming position 30. To start.

  As a result, the sheet is transported through the first sheet transport path 31 by the registration roller 32 so that the leading end of the sheet faces the leading end of the toner image at the image forming position 30.

  Note that the registration roller 32 also has a function of correcting the oblique feeding of the paper by abutting the leading edge of the paper while the rotation is stopped.

  The sheet on which the toner image is transferred at the image forming position 30 is guided to the fixing unit 33. The fixing unit 33 includes a heating roller 33A that has been heated to the toner melting temperature, and a pressure roller 33B that is in pressure contact with the heating roller 33A with a predetermined nip pressure. The paper is heated and pressurized when passing through the fixing unit 33, and is discharged to the post-processing device 3 with the toner image fixed on the surface.

  At the image forming position 30, all of the toner image attached to the peripheral surface of the intermediate transfer belt 11 should be transferred to the sheet. However. Some may remain on the intermediate transfer belt 11. In addition, the toner image attached to the peripheral surface of the intermediate transfer belt 11 may pass through the image forming position 30 without being transferred to the paper by the processing described later. The toner remaining on the intermediate transfer belt 11 after passing through the image forming position 30 is collected by the cleaning unit 13.

  On the other hand, the post-processing device 3 carries the paper discharged from the option delivery port 85 of the image forming device 2 into the device, performs each post-processing, and loads it on the paper discharge tray. Post-processing includes stapling the paper, discharging the paper to a designated paper discharge tray among a plurality of paper discharge trays, and offsetting the discharge position on the paper discharge tray.

  FIG. 3 is an enlarged view of the post-processing device 3. In the present embodiment, as post-processing, a staple process for stapling a sheet and a punch process for punching a sheet can be supported.

  The post-processing device 3 includes an entrance roller 171, a stapler 172, a punch pin 178, an alignment processing unit 173, a paper discharge roller 174, a paper rear end detection sensor 176, a paper discharge tray 175, and the like. The sheet discharged by the first sheet discharge roller 34 of the image forming apparatus 2 is conveyed to the alignment processing unit 173 by the entrance roller 171, and the alignment processing unit 173 sequentially aligns the sheets on the processing table. . The alignment processing unit 173 includes an alignment plate, a paddle, a scraping belt, and the like.

  In the case of stapling, the stapler 172 performs stapling at a designated location on the aligned bundle of sheets. The stapled sheet bundle is discharged onto a discharge tray 175 by a discharge roller 174.

  In the punching process, when the sheet trailing edge detection sensor 176 detects the trailing edge of the sheet, the sheet conveyance is temporarily stopped and the punch pin 178 punches a hole at the trailing edge of the sheet. Thereafter, the sheet is conveyed to the alignment processing unit 173 and aligned, and then discharged onto the discharge tray 175 by the discharge roller 174.

  FIG. 4 is a diagram illustrating a configuration of a main part in the vicinity of the first paper transport path 31, the duplex transport path 36 branched from the first paper transport path 31, and the right-side paper discharge transport path 39 in the paper transport unit 8 of the image forming apparatus 2.

  As described above, the first paper transport path 31 is formed in the image forming apparatus 2 from the paper storage unit 7 to the post-processing device 3 via the image forming position 30 of the image forming unit 6. Yes. In the first paper transport path 31, paper is fed from the paper storage unit 7 and the paper feed cassettes of the paper feed devices 4 and 5. Whether or not paper is fed from each paper feed cassette is detected by a paper feed sensor 41 provided corresponding to each paper feed cassette.

  Further, a registration sensor 44 is disposed in the vicinity of the registration roller 32 disposed in the first paper transport path 31. The registration sensor 44 detects whether or not the leading edge of the paper has reached the arrangement position of the registration roller 32.

  The first paper discharge roller (first discharge unit) 34 disposed in the first paper transport path 31 is configured to be driven forward and reverse. The first paper discharge roller 34 is driven to rotate forward to convey the paper to the post-processing device 3 through the option delivery port 85. Further, the first paper discharge roller 34 is driven to rotate in the reverse direction with the trailing edge of the paper being chucked, so that the paper is switched back.

  A first paper trailing edge detection sensor 61 is disposed in the vicinity of the first paper discharge roller 34. The first paper trailing edge detection sensor 61 detects whether or not the trailing edge of the paper conveyed to the post-processing device 3 has reached the first paper discharge roller 34. In the present specification, the trailing edge and the leading edge of the paper are referred to the paper conveyance direction. Therefore, the front end and the rear end are switched before and after the switchback conveyance.

  In the case of the image forming system 1 of the present embodiment, the double-sided conveyance path 36 and the right-side discharge conveyance path 39 branched from the first paper conveyance path 31 partially share the path branched from the first paper conveyance path 31. is doing. A first conveyance roller 81 is arranged on the common path 42, and on the downstream side of the first conveyance roller 81 (downstream in the conveyance direction of the paper to be switched back), the double-side conveyance path 36 and the right-side discharge conveyance. Branching to the road 39.

  Second and third transport rollers 82 and 83 are further disposed in the double-sided transport path 36, and a second paper discharge roller (second discharge unit) 84 is further disposed in the right-side paper discharge transport path 39. . In the image forming system 1 of the present embodiment, the first to third transport rollers 81 to 83 and the second paper discharge roller 84 are also configured to be able to be driven forward and reverse.

  The first to third transport rollers 81 to 83 are driven forward so that the paper that is switchback transported by the first paper discharge roller 34 passes through the double-side transport path 36 to the registration roller 32 again. Transport. Further, the first to third transport rollers 81 to 83 are reversely driven to transport the paper drawn into the double-side transport path 36 toward the first paper discharge roller 34 again.

  Further, the first transport roller 81 and the second paper discharge roller 84 are driven forward so that the paper that is switched back by the first paper discharge roller 34 is discharged to the right side through the right paper discharge port 86. It is conveyed onto the paper tray 72. Further, the first transport roller 81 and the second paper discharge roller 84 are driven in reverse so that the paper transported onto the right paper discharge tray 72 is switched back and transported again, and the first paper discharge roller again. Transport toward 34.

  A second paper trailing edge detection sensor 62 is disposed in the vicinity of the first transport roller 81. The second paper trailing edge detection sensor 62 is switchback conveyed by the first paper discharge roller 34, and the rear edge of the paper conveyed through the shared path 42 to the double-sided conveyance path 36 or the right side discharge conveyance path 39 side. Detects whether the first roller has reached the first conveying roller 81.

  A third paper trailing edge detection sensor 63 is disposed in the vicinity of the second paper discharge roller 84. The third paper trailing edge detection sensor 63 is switched back by the first paper discharge roller 34 and whether or not the rear edge of the paper conveyed to the right paper discharge tray 72 has reached the second paper discharge roller 84. Is to detect.

  A first gate 75 (FIG. 5A to FIG. 5A) that switches the paper conveyance direction is provided at a first branching portion 70 where the common path 42 of the double-side conveyance path 36 and the right discharge conveyance path 39 branches from the first sheet conveyance path 31. FIG. 5 (c)) is arranged. A second gate 76 (FIG. 6 (a) to FIG. 6 (c) for switching the paper transport direction is provided to the second branching portion 71 that branches the shared path 42 into the double-sided transport path 36 and the right-side paper transport path 39. )) Is provided.

  As shown in FIG. 5A, the first gate 75 is a fan-shaped gate, and normally stands by with the first paper transport path 31 closed. Then, the sheet conveyed upward along the first sheet conveyance path 31 abuts on the first gate 75 to rotate around the fulcrum 75a using the force of the sheet, and the state shown in FIG. It becomes. The state shown in FIG. 5B is maintained while the paper is passing, and when the paper has passed, the first gate 75 rotates by its own weight, as shown in FIG. 5C. Return to the original state.

  Here, the first gate 75 is transported from the shared path 42 toward the first branch portion 70 regardless of the state shown in FIG. 5A or the state shown in FIG. It is configured so as not to hinder the conveyance of the paper.

  Here, the first gate 75 has a fan shape and is rotated using the stiffness of the paper conveyed through the first paper conveyance path 31 and the weight of the first gate 75 itself. It is good also as a structure to drive.

  On the other hand, the second gate 76 rotates at the fulcrum 76a and can take three states shown in FIGS. 6 (a) to 6 (c). 6A shows a state in which a sheet conveyed from the shared path 42 toward the second branch portion 71 is guided to the right sheet discharge conveyance path 39. FIG. FIG. 6C shows a state in which the sheet conveyed toward the branching portion 71 is guided to the double-sided conveyance path 36, and FIG. 6C shows a second state from the double-sided conveyance path 36 and the right-side discharge conveyance path 39 that opens the second branching section 71. In this state, the sheet conveyed toward the branching unit 71 is guided to the shared path 42. The second gate 76 is driven by driving a solenoid (not shown) or the like.

  Next, the configuration of the control unit 50 of the image forming apparatus 2 will be described with reference to FIG. FIG. 7 is a block diagram illustrating a configuration of the control unit 50 of the image forming apparatus 2. The control unit 50 of the image forming apparatus 2 includes an image control unit (hereinafter referred to as ICU) 51, a process control unit (hereinafter referred to as PCU) 52, and an operation control unit (hereinafter referred to as OCU) 53.

  The OCU 53 includes a work memory 55 and an operation panel 57 is connected thereto. The OCU 53 stores the operation information input from the operation panel 57 in the work memory 55. The OCU 53 supplies operation information related to image processing for image information to the ICU 51 and supplies information related to image formation to the PCU 52.

  The ICU 51 includes an image memory 54 and a data input unit 56 is connected thereto. The ICU 51 performs predetermined image processing on the image information input from the outside via the data input unit 56 based on the operation information input from the OCU 53 and stores it in the image memory 54.

  The PCU 52 is connected to load devices 58 and 59 such as a motor and a clutch provided in each of the image forming unit 6 and the sheet conveying unit 8 and the post-processing device 3. The PCU 52 transmits post-processing information for the paper to the control unit 60 of the post-processing device 3. As post-processing information, information such as the position to be stapled and the number of staples is transmitted together with the content of post-processing.

  Based on the post-processing information transmitted from the PCU 52, the control unit 60 of the post-processing device 3 transmits post-processing time information required when post-processing is performed to the PCU 52. The post-processing time is determined in advance depending on the content of the post-processing, for example, the number of stops in the staple processing, and whether or not the punch processing is performed at the same time.

  The control unit 60 of the post-processing device 3 includes a table in which the content of the post-processing and the post-processing time are associated with each other, and transmits the post-processing time to the PCU 52 based on the table. A similar table may be provided on the PCU 52 side.

  The PCU 52 receives detection signals from various sensors 69 such as the paper feed sensors 41, the registration sensor 44, and the first to third paper trailing edge detection sensors 61 to 63 described above.

  The PCU 52 uses the detection signals of the various sensors 69, the operation information input from the OCU 53, and the post-processing time information input from the control unit 60 of the post-processing device 3 to describe the load devices 58 and 59 later. Drive like this.

  Next, overlapping paper discharge in the image forming system 1 will be described. In the multi-sheet discharge, when a double-sided image forming job is executed, it is necessary to delay paper feeding timing for image formation of the next section in order to secure time for post-processing of the previous section. In this case, the paper discharge mode is executed.

  In the overlap discharge, the first sheet of the next portion is retracted to the right discharge conveyance path 39, the double discharge that is simultaneously discharged while being superimposed on the second sheet, There is a triple sheet discharge in which the second sheet is retracted one by one in the duplex conveyance path 36 and the right sheet discharge conveyance path 39, and the sheet is overlapped with the third sheet and discharged simultaneously.

  In the case of a 3, 2, or 2 paper feed discharge pattern, which will be described later, in which only the first copy of the first copy is fed three sheets, and thereafter, two sheets are fed and ejected two by two. The paper discharge to the post-processing device 3 can be delayed by a maximum of three sheets.

  Further, in the same 3, 2, 2 paper feed / discharge pattern, in the triple paper discharge, discharge of paper to the post-processing device 3 can be delayed by a maximum of four sheets.

  FIG. 1 shows a block diagram of a function for carrying out double discharge and triple discharge. Condition determining unit (condition determining unit) 91, paper feed delay necessity determining unit (paper feed delay necessity determining unit) 90, retraction enable / disable determining unit (retraction enable / disable determining unit) 92, overlap discharge control unit (overlap discharge control) Means) 93 and an image forming order adjusting unit (image forming order adjusting means) 94. Each of these parts is composed of the PCU 52 and the ICU 51 described above.

  Here, the condition determination unit 91 determines whether the image forming condition is double-sided image formation, the number of sheets constituting one copy is three or more, and the number of copies is two or more. Whether or not double-sided image formation is performed and the number of sheets and the number of copies of one copy can be determined from the conditions input by the user using the operation panel 57 in the case of copying. Further, in the case of a printer job that outputs data transmitted from a PC, it can be determined from information on image forming conditions attached to the data.

  The paper feed delay necessity determination unit 90 determines whether or not it is necessary to delay the paper feed timing for the next paper in order to perform post-processing of the previous paper that has been discharged first in the transport plan. To do. Whether post-feed timing for the next set of paper needs to be delayed in order to perform post-processing of the previous unit that was previously ejected depends on the post-processing time that is determined by the specified post-processing conditions And the basic transport plan for 3,2,2 paper feed and discharge, comparing the time from when the last sheet of the previous section is ejected to when the first sheet of the next section is ejected. I can judge. The paper feed delay necessity determination unit 90 also calculates a necessary delay time and outputs the calculated delay time to the overlapped paper discharge control unit 93.

  The retractability determination unit 92 determines whether the sheet can be retracted to the double-sided transport path 36 in the transport plan. In other words, the paper on which the image formation on the first surface has been completed in the state where the paper is retracted to the double-sided conveyance path 36 used for double-sided image formation is used for the double-sided conveyance path for image formation on the second side. If it is conveyed to 36, it is determined that it cannot be retracted. Further, from the relationship between the length of the paper in the transport direction and the transport path length of the double-sided transport path 36, the sheet waiting on the double-sided transport path 36 and the double-sided transport path 36 for image formation on the second surface. It is also determined that the sheet cannot be retracted even when it comes into contact with the sheet retracted.

  The overlap discharge control unit 93 determines that the condition determination unit 91 is for double-sided image formation, one copy is 3 or more, and the number of copies is 2 or more. If it is determined that the timing needs to be delayed, the paper transport mechanism of the first paper transport path 31, the double-side transport path 36, and the right paper discharge transport path 39 to perform double paper discharge or triple paper discharge, The first and second gates 75 and 76, the first and second discharge rollers 34 and 84, and the first to third transport rollers 81 to 83 are controlled. However, in the present embodiment, the first gate 75 does not need to be controlled.

  Whether the double discharge control unit 93 performs the double discharge or the triple discharge can be fixed in advance to either one, but in the present embodiment, the multiple discharge control unit 93 No. 93 is configured to perform double discharge when the retractability determination unit 92 determines that the sheet cannot be retracted to the duplex conveyance path 36, and performs triple discharge when it is determined that the sheet can be retracted. In addition, based on the necessary delay time calculated by the paper feed delay necessity determination unit 90, the overlapping paper discharge control unit 93 can determine whether or not the post-processing time of the previous unit can be secured by double paper discharge. If it is possible, double discharge is selected even if triple discharge is possible.

  Detection signals from the paper feed sensors 41, the first to third paper trailing edge detection sensors 61 to 63, and the like are input to the overlapping paper discharge control unit 93. Based on these detection signals, the second gate 76 and the second gate 76 are detected. The first and second paper discharge rollers 34 and 84, the fourth transport roller 87, and the first to third transport rollers 81 to 83 are controlled as described later.

  On the other hand, the image forming order adjusting unit 94 adjusts the image forming order in consideration of the stacking order of sheets to be stacked and discharged when double discharge and triple discharge are performed. In other words, in the case of overlapping paper discharge, the sheets may not be stacked in the paper supply order depending on the positional relationship of the transport path to be retracted. For example, in the paper transport path as shown in FIG. 4, in the case of double paper discharge, the second paper fed second in the next section is at the bottom, and the first paper fed 1 The second sheet is stacked on the second sheet. In the triple paper discharge, the third sheet of the third sheet fed in the next section is at the bottom, and the second sheet and the third sheet are stacked in that order.

  Therefore, the image forming sequence adjusting unit 94 is arranged such that when it is discharged face-down to the post-processing device 3, the second sheet that has been fed second is used in the double discharge so that the sheets are stacked in page order. On the first side (front side) of the paper, an image of the second page of the original (the first back side image if a double-sided original) is formed, and on the second side (back side) of the second paper, the original 1 An image of the page (first surface image for a double-sided document) is formed, and an image of the second page of the document (2 for a two-sided document is first printed on the first side of the first sheet fed. Image so that the image of the third page of the document (or the front image of the second sheet in the case of a double-sided document) is formed on the second surface of the switchback conveyed paper. Adjust the formation order.

  In the case of triple paper discharge, an image of the second page of the document (the first back image if a double-sided document) is formed on the first side of the third sheet fed third. On the second side (back side) of the first sheet of paper, an image of the first page of the document (the front side image of the first sheet in the case of a double-sided document) is formed, and the second sheet fed second An image of the fourth page of the document (the second back image if a double-sided document) is formed on the first side, and an image of the third page of the document (a two-sided document is used on the second side of the second sheet). If there is a second front image), an image of the sixth page of the original (the third back image if a double-sided original) is formed on the first side of the first sheet fed first. The image formation order is adjusted so that the image on the second page of the first sheet is formed and the image of the fifth page of the document (the front surface image of the third page if a double-sided document) is formed.

  First, double discharge will be described with reference to FIGS. 8 (a) and 8 (b). FIGS. 8A and 8B are diagrams showing a conveyance plan in a case where four or more copies of a three-sided original are copied on both sides. Among these, FIG. 8A shows a transport plan that does not use double paper discharge in the 3,2,2 paper feed paper discharge pattern, and FIG. 8B shows the 3,2,2 paper feed paper discharge pattern. This is a transport plan using double paper discharge.

  In FIG. 8A and FIG. 8B, the length in the horizontal direction indicates the passage of time. The rectangle represents, for example, an A4 size sheet that is laterally fed, and the space between the rectangle represents the space between the sheets. The numbers in the rectangle and the characters “back” and “front” indicate the original image formed on the paper. The numbers indicate the number of the double-sided original composed of three sheets. The characters “back” indicate which of the front and back images of the double-sided document is formed on the paper. Further, in order to clarify the difference between the parts, for the even-numbered parts that are the second part and the fourth part, the numbers indicating the number of the originals are circled numbers. In addition, p1, p2, p3,..., P1, P2, P3,.

  According to FIG. 8A, for the first copy, three sheets of paper p1, p2, and p3 are normally fed in sequence. The normal paper feeding is paper feeding from the paper storage unit 7.

  When passing the image forming position 30 for the first time, the back side image of the first sheet of the original is formed on the first side of the first sheet p1, and the original is formed on the first side of the second sheet p2. A second back image is formed, and a third back image of the original is formed on the first surface of the third sheet p3.

  The three sheets p1, p2, and p3 on which the back image is formed are sequentially sent to the duplex conveyance path 36. Of these, the first sheet p1 and the second sheet p2 are continuously conveyed on both sides. When the paper is fed from the path 36 and passes the image forming position 30 for the second time, the front surface image of the first original is formed on the second surface of the first paper p1, and the second paper p2 On the second surface, a front image of the second original is formed. Thereafter, the paper is discharged to the post-processing device (option) 3.

  The third sheet p3 is kept waiting in the duplex conveyance path 36, and after the second sheet p2 passing the image forming position 30 for the second time, the second sheet p4, The second copy of the second sheet p5 is normally fed and conveyed. On the first side of the second sheet of the first sheet p4, the first back side image of the original is formed when passing the image forming position 30 for the first time. On the front side, a back side image of the second original is formed.

  The third sheet p3 of the first copy that has been waiting in the duplex conveyance path 36 is fed after the second sheet p5 of the second set, and the image forming position 30 is set a second time. When passing, a surface image of the third original is formed on the second surface, and then discharged to the post-processing device 3.

  When the third sheet p3, which is the last sheet of the first copy, is discharged to the post-processing apparatus 3, the post-processing apparatus 3 performs post-processing on these three sheets. The time required for post-processing varies depending on post-processing conditions. In the conveyance plan of FIG. 8A, the image forming apparatus 2 delays the sheet feeding timing for three sheets of one side of the sheet, and secures a post-processing time.

  During this time, the second sheet of the first sheet p4 waits in the double-sided conveyance path 36, and the second sheet of the second sheet p5 is subsequently switched back and fed into the double-sided conveyance path 36. Wait in the state.

  When the standby for a predetermined period secured for post-processing is completed, the image forming apparatus 2 resumes the conveyance of the sheet, and feeds the second sheet of the first sheet p4 from the duplex conveyance path 36. On the second surface of the second copy of the first sheet of paper p4, the first surface image of the original is formed when passing the image forming position 30 for the second time, and is then discharged to the post-processing device 3. The

  On the other hand, the second sheet p5 of the second set is further kept waiting in the double-sided conveyance path 36, and after the second sheet of the first sheet p4 that passes the image forming position 30 for the second time. The second set of third sheet p6 and the third set of first sheet p7 are normally fed and conveyed. On the first surface of the second sheet of the third sheet P6, the back side image of the third sheet of the original is formed when passing the image forming position 30 for the first time. On the first side of the paper p7, the back side image of the first original is formed.

  The second copy of the second sheet p5 that has been waiting in the duplex conveyance path 36 is conveyed after the first copy of the third sheet p7 that passes the image forming position 30 for the first time, Subsequently, the second copy of the third sheet p6 is fed. The third sheet of the first sheet P7 is made to wait in the duplex conveyance path 36.

  Since this is the same, the detailed description will be omitted. However, after the third sheet P9 of the third set that passes the image forming position 30 for the first time, the first sheet of the third set is printed. The sheet P7 is fed from the duplex conveyance path 36, but in order to secure the post-processing time for the second copy, the image forming apparatus 2 can form an image on one side of the sheet, and one sheet for the third copy. The paper feeding from the double-sided conveyance path 36 of the eye paper P7 is delayed.

  As described above, in the transport plan that does not use double paper discharge in the 3, 2, 2 paper feed paper discharge pattern, after the last sheet of the previous part is discharged to the post-processing device 3, the first of the next part is discharged. The sheet feeding timing from the double-sided conveyance path 36 of the first sheet of the next section is set so that the interval between the sheets until the sheet is discharged to the post-processing device 3 is left for the time required for the post-processing of the preceding section. Delay.

  On the other hand, FIG. 8B is the same as FIG. 8A until the third sheet P3, which is the last sheet of the first copy, is discharged to the post-processing device 3. However, since it is necessary to change the order of the images to be formed in consideration of the stacking order by the double discharge, the image order is adjusted for the paper to be double discharged. Specifically, the back side image of the second original is formed on the first side of the first sheet P4 of the second copy, and the first page of the original is formed on the first side of the second sheet P5 of the second copy. Is formed. Further, the front surface image of the second document is formed on the second surface of the first sheet P4 of the second copy, and one document is formed on the second surface of the second sheet P5 of the second copy. A surface image of the eye is formed.

  In FIG. 8A, after the third sheet p3, which is the last sheet of the first copy, is discharged to the post-processing device 3, the timing of feeding the sheet from the duplex conveying path 36 is changed to the sheet one side. Although it was delayed by three sheets, in FIG. 8B, the second sheet of the first sheet P4 is conveyed on both sides following the first sheet of the last sheet P3 without delaying the feeding timing. Paper is fed from the path 36 to form an image on the second surface. The paper on which the image formation on the second surface has been completed is normally discharged to the post-processing device 3 as it is, but here, the second sheet of the first sheet P4 is discharged to the right side. The paper is temporarily retracted to the paper transport path 39.

  After the second sheet of the first sheet P4 that passes the image forming position 30 for the second time, the second sheet of the third sheet P6 and the third sheet of the first sheet P7 are normally fed. Then transported. The second sheet P5 of the second copy that has been waiting in the duplex conveyance path 36 is attached after the first sheet P7 of the third set that passes the image forming position 30 for the first time, and is conveyed by both sides. When the paper is fed from the path 36 and passes the image forming position 30 for the second time, the image formation on the second surface is completed. Then, the second copy of the second sheet P5 on which the double-sided image formation has been completed is discharged to the post-processing device 3. At this time, the second copy of the second copy P5 that has been retracted to the right discharge conveyance path 39 is discharged. The first sheet P4 is overlaid and discharged at the same time.

  In this way, by discharging the second copy of the first sheet P4 and the second copy of the second sheet P5, without delaying the feeding timing of the second set of sheets, The time for forming an image on one side of the paper P4, P6, P7 can be used for the post-processing of the first copy.

  After the second and first sheets of paper P4 and P5 are stacked and discharged, the second and third sheets of paper P6 are fed from the duplex conveying path 36, and the second sheet P6 is fed. After the image formation on the surface is completed, the image is discharged to the post-processing device 3.

  After the second third sheet P6 passing through the image forming position 30 for the second time, the third second sheet P8 and the third third sheet P9 are normally fed. Then transported. After the third copy of the third sheet P9 that passes the image forming position 30 for the first time, the third copy of the first sheet P7 that has been waiting in the duplex conveyance path 36 is fed. Then, when passing the image forming position 30 for the second time, an image is formed on the second surface. As described above, the sheet on which the image formation on the second surface has been completed is normally discharged to the post-processing device 3 as it is, but here again, the third sheet of the first sheet P7 is The paper is temporarily retracted to the right paper delivery path 39, and is then fed simultaneously from the second sheet P8 of the third set on which the paper is fed from the double side delivery path 36 and image formation is performed on the second side. Is done.

  In this way, by discharging the third sheet of the first sheet P7 and the third sheet of the second sheet P8, without delaying the sheet feeding timing of the third sheet, The time required to form an image on one side of each of the sheets P8, P9, and P7 can be used for post-processing of the second copy.

  In the conveyance plan of FIG. 8 (a) and the conveyance plan of FIG. 8 (b), as can be understood by comparing the feeding timings of the fourth sheet of the second sheet p11 and P11, the sheet is divided into four sections. Job efficiency can be increased by 4 sheets per side.

  Next, with reference to FIGS. 9A to 9C and FIGS. 10A to 10C, the portion of the conveyance plan in FIG. Shows the flow of paper. In the drawing, the paper on which image formation on both sides (first side and second side) has been completed is indicated by a thick black line, and the paper on which image formation has been completed on the first side is indicated by a gray thick line. A sheet not marked with is indicated by a thick dotted line.

  FIG. 9A shows a state in which the first sheet P3 of the first copy has completed image formation on both sides and is discharged to the post-processing device 3 through the first discharge roller 34. . At this time, the second copy of the first sheet P4 is fed from the duplex conveyance path 36 and the image is formed on the second surface, and the second copy of the second sheet P5 is After the image formation on the first surface is completed, the double-sided conveyance path 36 is being conveyed.

  Next, in FIG. 9B, the second sheet of the first sheet P4 has completed image formation on both sides, and the second sheet of the third sheet P6 is in a state of being normally fed. . The second sheet P5 of the second copy is waiting in the duplex conveyance path 36.

  Next, in FIG. 9C, since the image formation on both sides is normally completed, the second copy of the first copy is discharged to the post-processing device 3 through the first discharge roller 34 as it is. The sheet P4 is being conveyed to the right sheet discharge conveyance path 39 through the second sheet discharge roller 84 for temporary retraction due to reverse rotation of the first sheet discharge roller 34 and the like. Further, the image formation on the first side of the second copy of the third sheet P6 is completed, and the third copy of the first sheet P7 is normally fed. The second sheet P5 of the second copy is waiting in the duplex conveyance path 36.

  Next, in FIG. 10A, the first sheet P4 of the second copy is retracted on the right discharge tray 72 shown in FIG. The second copy of the third sheet P6 is in a state where the image formation on the first surface is completed and the sheet P6 is conveyed to the duplex conveyance path. The first sheet P7 of the third set is formed on the first side, and the second sheet P5 of the second set is fed from the duplex conveyance path 36 to the first for forming the image on the second side. The conveyance to the conveyance path 31 is started.

  Next, in FIG. 10B, the second copy of the third sheet P6 is transported on both sides while the second copy of the first sheet P2 is temporarily retracted to the right paper discharge transport path 39. The first sheet P7 of the third copy that has been transported through the path 36 has completed image formation on the first surface, and is transported to the duplex transport path 36, and the second sheet P5 of the second copy includes the first sheet P5. Image formation on two sides is performed.

  Next, in FIG. 10C, when the first sheet P7 of the third set is completely transported to the duplex transport path 36, the first sheet P4 of the second set is retracted. The conveyance from the right sheet discharge conveyance path 39 to the first sheet discharge roller 34 is started. Then, the second copy of the first sheet P4 is timed so that the leading edge of the second copy of the second sheet P5 on which the image formation on both sides has been completed is aligned and discharged to the post-processing device 3. Is done.

  Since the second copy of the first sheet P4 is stacked on the second copy of the second sheet P5 and discharged, the second copy of the first sheet P4 includes the second copy of the original. The front and back images are formed face down, and the first and second images of the original document are formed face down on the second sheet P5 of the second copy.

  As described above, the timing at which the next sheet is discharged to the post-processing apparatus 3 after the third sheet P3 of the first copy, which is the last sheet in the prior art, is discharged to the post-processing apparatus 3 is shown in FIG. 9 (b), the first sheet P4 of the second copy is completed on both sides and is conveyed to the first discharge roller 34. As described above, as shown in FIG. By delaying the timing until the second sheet P5 of the second copy is discharged, it is possible to earn post-processing time for three sheets on one side of the sheet. Even when the post-processing time exceeds the discharge delay time for three sheets on one side, the time for delaying image formation of the next portion can be shortened.

  Next, double discharge control in the overlap discharge control unit 93 will be described. FIG. 11 is a control flow of double discharge of the overlap discharge control unit 93.

  Double-sided image formation is started on the second sheet of the first sheet P4 (S1). When the double-sided image formation of the second copy of the first sheet P4 is started, the processing is the process related to the second copy of the first sheet P4 in S2 to S13, and the second copy of the second copy of S15 and S16. The two processes of the paper P5 are processed in parallel.

  First, processing related to the second copy of the first sheet P4 will be described. In S2, whether or not the trailing edge of the second sheet of the first sheet P4 has reached the first paper discharge roller 34 (whether or not the trailing edge of the sheet has been detected by the first sheet trailing edge detection sensor 61). ), The first discharge roller 34 is stopped (S3), the second gate 76 is switched to the right discharge conveyance path 39 (S4), and then the first discharge roller 34 is driven in reverse, and the first transport roller 81 and the second paper discharge roller 84 are driven forward (S5).

  Next, at S6, whether or not the trailing edge of the second sheet of the first sheet P4 has reached the second paper discharge roller 84 (the trailing edge of the sheet is detected by the third sheet trailing edge detection sensor 63). If it has been reached, the first and second paper discharge rollers 34 and 84 and the first transport roller 81 are stopped (S7), and the second gate 76 is moved in the direction of the double-side transport path 36. After switching (S8), it waits for the counter T to be increased (S9).

  The counter T is for determining the resumption timing of the conveyance of the second sheet, the first sheet P4. The timing of resuming the conveyance of the second copy of the first sheet P4 is the second copy of the second copy 2 in which the leading edge of the second copy of the first sheet P4 that has been conveyed is conveyed on the first sheet conveyance path 31. This is the timing when the leading edge of the sheet P5 is aligned.

  When the counter T is UP, the counter T is cleared (S10), and whether or not there is paper on the first transport roller 81 in S11 (whether the first transport roller 81 is stopped or the first transport roller 81 is rotated). The second paper trailing edge detection sensor 62 detects the trailing edge of the paper and whether or not a predetermined time has passed. After switching to the direction 39 (S12), the first paper discharge roller 34 is driven to rotate forward, and the first transport roller 81 and the second paper discharge roller 84 are driven to rotate backward (S13). However, the predetermined time here is for completely extracting the trailing edge of the sheet being conveyed from the first conveying roller 81.

  On the other hand, in S15, whether or not double-sided image formation has started on the second sheet of the second sheet P5 (whether or not the registration roller 32 has been activated for the conveyance of the second sheet of the second sheet P5). If it is determined that it has been started, the counter T is started (S16).

  By such control, the 22nd first sheet P4 returned to the first sheet conveying path 31 and the first sheet are once pulled into the right sheet conveying path 39 and the counter T is increased. The second copy of the second sheet P5 transported on the transport path 31 is that the first copy P4 of the second copy overlaps the second copy P5 of the second copy, and the leading ends of each other are In the aligned state, they are simultaneously discharged to the post-processing device 3 (S9).

  Next, triple discharge will be described with reference to FIGS. 12 (a) and 12 (b). 12 (a) and 12 (b) are diagrams showing a conveyance plan in a case where four or more copies of a three-sided original are copied on both sides. Of these, FIG. 12A shows a transport plan that does not use triple discharge in the 3,2,2 paper feed discharge pattern, and FIG. 12B shows the 3,2,2 paper feed discharge pattern. This is a transport plan using triple paper discharge.

  The transport plan in FIG. 12A is almost the same as that in FIG. 8A, but in FIG. 12A, the last sheet of the first copy is used in order to increase the post-processing time of the first copy. After the third sheet p3 is discharged to the post-processing device 3, the sheet feeding from the duplex conveyance path 36 is delayed for a period of time during which an image can be formed on four sheets on one side of the sheet. Also, for the post-processing of the second set, the third sheet p9, which is the last sheet of the third set, is normally fed to form an image on the first side, and then the second sheet is fed from the double-sided conveyance path 36. The feeding of the first sheet p7 of the third copy is delayed by two sheets on one side.

  On the other hand, FIG. 12B is the same as FIG. 12A until the third sheet P3, which is the last sheet of the first copy, is discharged to the post-processing device 3. However, since it is necessary to change the order of the images to be formed in consideration of the stacking order by the triple discharge, the image order is adjusted for the paper to be triple discharged. Specifically, the back side image of the third original is formed on the first side of the first sheet P4 of the second copy, and the second side of the original is formed on the first side of the second sheet P5 of the second copy. Is formed, and the back image of the first document is formed on the first surface of the third sheet P6 of the second copy. Further, the front surface image of the third document is formed on the second surface of the first sheet P4 of the second copy, and two documents are formed on the second surface of the second sheet P5 of the second copy. On the second surface of the second sheet of the third sheet P6, the first surface image of the original is formed.

  In FIG. 12A, after the third sheet p3, which is the last sheet of the first copy, is discharged, the sheet feeding timing from the duplex conveyance path 36 is delayed by four sheets on one side. However, in FIG. 12B, the second sheet of the first sheet P4 is fed from the duplex conveyance path 36 after the first sheet of the last sheet P3 without delaying the sheet feeding timing. Paper is then formed on the second side. The sheet on which image formation on the second side has been completed is normally discharged to the post-processing device 3 as it is, but here, the first sheet P4 of the second set is discharged to the right side. The road 39 is temporarily retracted.

  After the second sheet of the first sheet P4 that passes the image forming position 30 for the second time, the second sheet of the third sheet P6 and the third sheet of the first sheet P7 are normally fed. Then transported. The second sheet P5 of the second copy that has been waiting in the duplex conveyance path 36 is attached after the first sheet P7 of the third set that passes the image forming position 30 for the first time, and is conveyed by both sides. Paper is fed from the path 36. As described above, the sheet on which image formation on the second surface has been completed is normally discharged to the post-processing device 3 as it is, but here, the second sheet P5 of the second set is discharged. Further, the sheet is temporarily retracted to the duplex conveyance path 36.

  The second copy of the third sheet P6 is fed from the duplex conveying path 36 after the second copy of the second sheet P5 that passes the image forming position 30 for the second time. When passing through the formation position 30, the image formation on the second surface is completed. Then, the second copy of the third sheet P6 for which double-sided image formation has been completed is discharged to the post-processing device 3. At this time, the second copy of the second copy that has been retreated to the double-sided conveyance path 36 is output. The sheet P5 and the second sheet of the first sheet P4 that have been retracted to the right sheet discharge conveyance path 39 are stacked on top of each other, and the three sheets are discharged at the same time.

  In this manner, the second copy of the first sheet P4 and the second copy of the third sheet P5 are overlapped with the second copy of the third sheet P6 to be discharged. The time for forming an image on four single-sided sheets P4, P6, P7, and P5 can be used for the first post-processing without delaying the sheet feeding timing.

  After the second sheet of the first sheet P4 and the second sheet of the second sheet P5 are overlaid on the second sheet of the third sheet P6 and discharged, The third sheet P8 of the third copy and the third sheet P9 of the third set are sequentially fed normally.

  After the third copy of the third sheet P9 that passes the image forming position 30 for the first time, the third copy of the first sheet P7 that has been waiting in the duplex conveyance path 36 is fed. Then, when passing the image forming position 30 for the second time, an image is formed on the second surface. As described above, the sheet on which the image formation on the second surface has been completed is normally discharged to the post-processing device 3 as it is, but here again, the third sheet of the first sheet P7 is The sheet is temporarily retracted to the right sheet delivery path 39.

  After the third copy of the first sheet P7 that passes the image forming position 30 for the second time, the second copy of the third sheet P8 is fed from the duplex conveying path 36. In order to increase the post-processing time for the four sheets on one side necessary for the post-processing of the eyes, the feeding of the second sheet P8 of the third copy is delayed by one sheet on one side.

  Here, the second sheet P8 of the third copy is not retracted to the duplex conveying path 36 to be triple discharged, but the second sheet P8 of the third set is not fed from the duplex conveying path 36. The reason why the paper feeding is delayed by one sheet on one side to make a double paper discharge is that the triple paper discharge using the retreat to the double-sided conveyance path 36 cannot be selected in the conveyance plan. More specifically, the fourth copy of the first sheet P10 conveyed to the first paper discharge roller 34 is conveyed to the duplex conveyance path 36 in order to form an image on the second surface. It is.

  When the image formation on the second surface is completed, the third sheet of the second sheet P8 discharged to the post-processing apparatus 3 is retracted to the right sheet discharge conveyance path 39. Two sheets are discharged simultaneously with the paper P7 of the eye.

  In this way, the first sheet P7 of the third copy is discharged on the second sheet P8 of the third copy, so that the delay of the feeding timing of the third set of sheets can be reduced. Can be reduced to one sheet.

  In the conveyance plan of FIG. 12A and the conveyance plan of FIG. 12B, as is understood by comparing the feeding timing of the second sheet p11 and P11 of the fourth set, the four sets are set. Job efficiency can be increased by 5 sheets per side.

  Next, using FIGS. 13A to 13C, FIGS. 14A to 14C, and FIGS. 15A and 15B, 3 surrounded by a one-dot chain line in the transport plan of FIG. 12B. The flow of a sheet in a portion where multiple paper discharge is performed is shown. In the drawing, the paper on which image formation on both sides (first side and second side) has been completed is indicated by a thick black line, and the paper on which image formation has been completed on the first side is indicated by a gray thick line. A sheet not marked with is indicated by a thick dotted line.

  FIG. 13A shows a state in which the first sheet of the third sheet P3 has completed image formation on both sides and is discharged to the post-processing device 3. At this time, the second copy of the first sheet P4 is fed from the duplex conveyance path 36 and the image is formed on the second surface, and the second copy of the second sheet P5 is After the image formation on the first surface is completed, the double-sided conveyance path 36 is being conveyed.

  Next, in FIG. 13B, the second sheet of the first sheet P4 has completed image formation on both sides, and the second set of the third sheet P6 is in a state of being normally fed. . The second sheet P5 of the second copy is waiting in the duplex conveyance path 36.

  Next, in FIG. 13C, since the image formation on both sides is normally completed, the second copy of the first sheet P4 discharged to the post-processing device 3 is discharged to the right side for temporary retraction. The paper is being conveyed to the paper conveyance path 39. At this time, the second sheet of the third sheet P6 has completed image formation on the first surface, and the third sheet of the first sheet P7 is normally fed. The second sheet P5 of the second copy is waiting in the duplex conveyance path 36.

  Next, in FIG. 14A, the second sheet of the first sheet P4 is retracted to the right sheet discharge conveyance path 39. Further, the second copy of the third sheet P6 has completed image formation on the first side and is conveyed to the duplex conveyance path 36, and the third copy of the first sheet P7 has image formation on the first side. The second sheet P5 of the second copy is started to be conveyed from the duplex conveyance path 36 to the first conveyance path 31 for image formation on the second side.

  Next, in FIG. 14B, the second copy of the third sheet P6 is transported on both sides while the second copy of the first sheet P4 is temporarily retracted to the right paper discharge transport path 39. The first sheet P7 of the third copy that has been transported through the path 36 has completed image formation on the first side and is transported to the duplex transport path 36, and the second sheet of the second sheet P5 includes the second sheet P5. An image is formed on the surface.

  Next, in FIG. 14C, the second copy of the second sheet P5 is further in a state where the second copy of the first sheet P4 has been temporarily retracted to the right paper discharge conveyance path 39. Originally, since the double-sided image formation has been completed, the paper is discharged to the post-processing device 3, but is transported to the double-sided transport path 36 in this schedule. Further, the second sheet of the third sheet P6 is formed on both sides, and the third sheet of the first sheet P7 is also transported in the duplex transport path. However, in order for the second sheet P5 of the second copy to be transported to the duplex transport path 36, the sheet transported to the first paper discharge roller 34 is completed for both-side image formation. It is a condition that the paper is the same. In the case of this schedule, since the next sheet to be conveyed is the second and third sheet P6 for which double-sided image formation has been completed, the conditions are met.

  Next, as shown in FIG. 15A, when the rear end of the second sheet P5 of the second set reaches the first transport roller 81, it is switched back again and transported to the first discharge roller 34. Is done. At this time, the second sheet of the first sheet P4 that has been retracted to the right-side sheet discharge conveyance path 39 through the second discharge roller 84 is also conveyed to the first sheet discharge roller 34 at the same time.

  As shown in FIG. 15B, the second and second sheets P5 and P4 of the second copy are respectively the second and third sheets P6 of which the double-sided image formation has been completed. The paper is discharged to the post-processing device 3 at the same timing so that the leading edges of the sheets are aligned.

  The second copy of the first sheet P4 is stacked on the second copy of the second sheet P5, and the second copy of the second sheet P5 is further stacked on the second copy of the third sheet P6. The front and back images of the third document are formed face down on the first sheet P4 of the second copy, and the document 2 is printed on the second sheet P5 of the second copy. The front and back images of the first sheet are formed face-down, and the display image of the first document is formed face-down on the third sheet P6 of the second copy.

  In the case of the present image forming system 1, a shared path 42 is provided by sharing a part of the double-sided conveyance path 36 and the right-side discharge conveyance path 39. 39, and the sheet retracted to the double-sided conveyance path 36 can be overlapped, so that it is easier to transport the leading edge than to transport the sheet from three directions and stack three sheets at a time. Can be aligned.

  As described above, the timing at which the next sheet is discharged to the post-processing apparatus 3 after the third sheet P3 of the first copy, which is the last sheet in the prior art, is discharged to the post-processing apparatus 3 is shown in FIG. The first sheet P4 of the second set of 13 (b) has completed image formation on both sides and is conveyed to the first discharge roller 34. As described above, this is illustrated in FIG. By delaying until the timing of discharging the second and third sheet P6 of b), post-processing time for four sheets on one side can be gained. Even when the post-processing time exceeds the discharge delay time for three sheets on one side, the time for delaying image formation of the next portion can be shortened.

  Next, the triple discharge control in the overlap discharge control unit 93 will be described. FIG. 16 is a control flow of triple paper discharge of the overlap paper discharge control unit 93.

  The double-sided image formation of the second copy of the first sheet P4 is started (S101). When the double-sided image formation of the second copy of the first sheet P4 is started, the processing is the processing related to the second copy of the first sheet P4 in S102 to S111 and the second copy of the second copy in S113 to S125. Two processes related to the paper P5 are processed in parallel.

  First, processing related to the second copy of the first sheet P2 will be described. In S112, whether or not the trailing edge of the second sheet of the first sheet P4 has reached the first paper discharge roller 34 (whether or not the trailing edge of the sheet has been detected by the first sheet trailing edge detection sensor 61). ), The first discharge roller 34 is stopped (S103), the second gate 76 is switched to the right discharge conveyance path 39 (S104), and then the first discharge roller 34 is rotated in the reverse direction, and the first transport roller 81 and the second paper discharge roller 84 are driven in the forward direction (S105).

  Next, in S106, whether or not the trailing edge of the second sheet of the first sheet P4 has reached the second paper discharge roller 84 (the trailing edge of the sheet is detected by the third sheet trailing edge detection sensor 63). If it has been reached, the first and second paper discharge rollers 34 and 84 and the first conveyance roller 81 are stopped (S107), and the second gate 76 is moved in the direction of the double-side conveyance path 36. After switching (S108), it waits for the counter T2 to be increased (S109).

  The counter T2 is for determining the resumption timing of the conveyance of the second sheet, the first sheet P4. The timing of resuming the conveyance of the second and first sheet of paper P4 is the second section where the leading edge of the second and first sheet P4 of which conveyance has been resumed is conveyed by the switchback on the duplex conveyance path 36. This is the timing when the leading edge of the first sheet P4 is aligned.

  When the counter T2 is UP, the counter T2 is cleared (S110), and the second paper discharge roller 84 is driven in reverse (S111).

  On the other hand, in S113, double-sided image formation is started on the second copy of the second sheet P5. When the double-sided image formation of the second copy of the second sheet P5 is started, the process further includes the processes related to the second copy of the second sheet P5 of S114 to S125, and the second set of three sheets of S126 and S127. Three of the processes related to the eye paper P6 are processed in parallel.

First, processing related to the second copy of the second sheet P5 will be described. In S114, whether or not the trailing edge of the second copy of the second sheet P5 has reached the first paper discharge roller 34 (whether or not the trailing edge of the sheet has been detected by the first sheet trailing edge detection sensor 61). ), The first discharge roller 34 is stopped (S115), the second gate 76 is switched in the direction of the duplex conveying path 36 (S116), and then the first discharge roller 34 is moved. In addition to the reverse drive, the first to third transport rollers 81, 82 and 83 are driven to rotate forward (S117).
Next, in S118, whether or not the trailing edge of the second sheet of the second sheet P5 has reached the first transport roller 81 (whether the trailing edge of the sheet has been detected by the second sheet trailing edge detection sensor 62). If it is determined that it has been reached, it is further determined whether or not a predetermined time has elapsed after the trailing edge of the sheet has arrived (S119). This predetermined time is for completely extracting the rear end of the second copy of the second sheet P5 from the first conveying roller 81. The distance between the first conveying roller 81 and the trailing edge of the sheet is controlled in this predetermined time.

  If it is determined that the predetermined time has elapsed, the first paper discharge roller 34 and the first to third transport rollers 81, 82, 83 are stopped (S120), and the process waits for the counter T1 to be increased (S121).

  The counter T1 is for determining the resumption timing of the conveyance of the second copy of the second sheet P5. The timing of resuming the conveyance of the second copy of the second sheet P5 is the second copy 3 in which the leading end of the second copy of the second copy of the second sheet P5 is conveyed on the first sheet conveyance path 31. This is the timing at which the leading edge of the sheet P6 is aligned.

  When the counter T1 is UP, the counter T1 is cleared (S122), and the second gate 76 is opened so that the paper can be carried in from both the double-sided conveyance path 36 and the right side discharge conveyance path 39 (S123). The first paper discharge roller 34 is driven to rotate forward, and the first to third transport rollers 81, 82, 83 are driven to rotate backward (S124), and the counter T2 is started (S125).

  On the other hand, in S126, it is determined whether or not double-sided image formation has started for the first sheet P6 of the second copy (whether the registration roller 32 has been activated for the conveyance of the first sheet P4 of the second set). If it is determined that it has been started, the counter T1 is started (S127).

  By such control, the second copy of the second sheet P5 that is once drawn into the duplex conveyance path 36 and returned to the first sheet conveyance path 31 by the counter T1 being increased, and the right-side discharge conveyance path 39. The second sheet of the first sheet P4 returned to the first sheet conveyance path 31 by the counter T2 being UP and the second sheet of the third sheet conveyed on the first sheet conveyance path 31 The second paper P6 overlaps the second and third paper P6 in the order of the second and second paper P5, and the second and first paper P4 in that order. The tips are aligned and discharged to the post-processing device 3 (S112).

  Next, with reference to FIGS. 17 (a) and 17 (b), overlapping discharge when the number of sheets constituting one copy is an even number will be described. FIGS. 17 (a) and 17 (b) are diagrams showing a conveyance plan in a case where three or more copies of a four-sided original are copied on both sides. Among these, FIG. 172 (a) is a basic conveyance plan that does not use overlapped paper discharge, and FIG. 17 (b) is a conveyance plan that uses overlapped paper discharge.

  Since the conveyance plan in FIG. 17A is composed of an even number of sheets, unlike the case of FIG. 8A in which the one section is composed of an odd number of sheets, the conveyance plan always includes two sheets on one side. Post-processing time can be secured. Accordingly, when the time required for three sheets on one side of the paper is required for the post-processing, the timing of feeding the second sheet, the first sheet p5, from the duplex conveyance path 36 can be ensured by delaying the sheet on one side. . That is, the job efficiency is high as compared with the case where a plurality of parts in which one part of FIG. However, job efficiency can be further improved by using double paper discharge.

  That is, in FIG. 17A, the paper feeding timing of the second copy of the first sheet p5 from the duplex conveyance path 36 is delayed by one sheet, but as shown in FIG. The second sheet of the first sheet P5 is fed without delaying the sheet feeding timing from the duplex conveying path 36 to form an image on the second side, and is temporarily retracted to the right discharge conveying path 39. After the double-sided image formation is completed, the paper is discharged on the second copy of the second sheet P6 to be discharged at the same time. Thereby, job efficiency can be improved.

  In the conveyance plan in FIG. 17A and the conveyance plan in FIG. 17B, as is understood by comparing the feeding timings of the fourth and fourth sheets p12 and P12 of the third set, the three sets of sheets Job efficiency can be increased by 2 sheets per side.

  Also in this case, in consideration of the stacking order by the double discharge, the back side image of the second original is formed on the first side of the first sheet P5 of the second copy, and the second copy of the second copy The back side image of the first original is formed on the first side of the paper P6. Further, the front surface image of the second original is formed on the second surface of the first sheet P5 of the second copy, and one original is formed on the second surface of the second sheet P6 of the second copy. A surface image of the eye is formed.

  In the image forming system according to the present exemplary embodiment, a condition determination unit (condition determination unit) 91, a paper feed delay necessity determination unit (paper feed delay necessity determination unit) 90, and a retractability determination unit (retractability determination unit) 92 In the above description, the overlap discharge control unit (overlap discharge control unit) 93 and the image formation order adjustment unit are described as being included in the control unit 50 of the image forming apparatus 2. It may be.

  Finally, in the image forming system 1, a condition determination unit (condition determination unit) 91, a paper feed delay necessity determination unit (paper feed delay necessity determination unit) 90, a retraction enable / disable determination unit (retraction enable / disable determination unit) 92, overlapping The paper discharge control unit (multiple paper discharge control unit) 93 and the image formation order adjustment unit may be configured by hardware logic, or may be realized by software using a CPU as follows.

  That is, the image forming system 1 includes a CPU (central processing unit) that executes instructions of a control program that realizes each function, a ROM (read only memory) that stores the program, and a RAM (random access memory) that expands the program. And a storage device (recording medium) such as a memory for storing the program and various data. An object of the present invention is a recording medium on which a program code (execution format program, intermediate code program, source program) of a control program of the image forming system 1 which is software for realizing the functions described above is recorded so as to be readable by a computer. This can also be achieved by supplying the image forming system 1 and reading and executing the program code recorded on the recording medium by the computer (or CPU or MPU).

  Examples of the recording medium include tapes such as magnetic tapes and cassette tapes, magnetic disks such as floppy (registered trademark) disks / hard disks, and disks including optical disks such as CD-ROM / MO / MD / DVD / CD-R. Card system such as IC card, IC card (including memory card) / optical card, or semiconductor memory system such as mask ROM / EPROM / EEPROM / flash ROM.

  The image forming system 1 may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication. A net or the like is available. Also, the transmission medium constituting the communication network is not particularly limited. For example, even in the case of wired such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL line, etc., infrared rays such as IrDA and remote control, Bluetooth ( (Registered trademark), 802.11 wireless, HDR, mobile phone network, satellite line, terrestrial digital network, and the like can also be used. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

1 is a functional block diagram illustrating a double discharge and a triple discharge in an image forming system according to an embodiment of the present invention. It is drawing which shows the structure of the said image forming system. 2 is a diagram illustrating a configuration of a post-processing device provided in the image forming system. 2 is a diagram illustrating a conveyance path configuration of a sheet conveyance unit of an image forming apparatus in the image forming system. FIGS. 5A to 5C are explanatory views showing the operation of the first gate disposed in the first branching section of the sheet conveying section of the image forming apparatus in the image forming system. FIGS. 6A to 6C are explanatory diagrams showing the operation of the second gate disposed in the second branching portion of the sheet conveying portion of the image forming apparatus in the image forming system. FIG. 2 is a block diagram illustrating a configuration of a control unit of an image forming apparatus in the image forming system. FIG. 8A is a diagram showing a conveyance plan that does not use double discharge of the 3,2,2 paper feed discharge pattern, and FIG. 8B is a 3,2,2 paper feed discharge pattern in the present embodiment. It is a figure which shows the conveyance plan using double discharge in. FIGS. 9A to 9C are explanatory diagrams showing the flow of double-discharged paper implemented in the image forming system. 9 (a) to 9 (c) are explanatory views showing the flow of the double-discharged paper carried out in the image forming system, and are shown in FIGS. 9 (a) to 9 (c). It is a continuation. It is a control flow of double paper discharge carried out in the image forming system. FIG. 12A is a diagram showing a conveyance plan using triple discharge of 3,2,2 paper feed / discharge patterns, and FIG. 12B is a diagram of 3,2,2 paper feed / discharge patterns in the present embodiment. It is a figure which shows the conveyance plan using triple discharge in. FIG. 13A to FIG. 13C are explanatory diagrams showing the flow of the triple-discharged paper implemented in the image forming system. 14 (a) to 14 (c) are explanatory views showing the flow of the triple-discharged paper carried out in the image forming system, and are shown in FIGS. 13 (a) to 13 (c). It is a continuation. FIGS. 15A and 15B are both explanatory views showing the flow of the triple-discharged paper carried out in the image forming system, and are shown in FIGS. 14A to 14C. It is a continuation. It is a control flow of triple paper discharge performed in the image forming system. FIG. 17A is a diagram showing a conveyance plan using double discharge of the 3,2,2 paper feed discharge pattern, and FIG. 17B is a 3,2,2 paper feed discharge pattern in the present embodiment. It is a figure which shows the conveyance plan using double discharge in.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming system 2 Image forming apparatus 3 Post-processing apparatus 31 1st paper conveyance path (main conveyance path)
36 Double-sided transport path (first sub-transport path)
39 Right-side paper delivery path (second sub-transport path)
42 Common path 90 Paper feed delay necessity judgment section (paper feed delay necessity judgment means)
91 Condition Judgment Unit (condition judging means)
92 Removability determination unit (evacuation determination unit)
93 Overlap discharge control unit (overlap discharge control means)
94 Image formation order adjustment unit (image formation order adjustment means)

Claims (8)

A paper supply unit storing paper, an image forming unit that forms an image on the paper, a first discharge unit that discharges the paper on which image formation has been performed in the image forming unit, and the image from the paper supply unit A main conveyance path for guiding the sheet to the first discharge section via the formation section, and a sheet on which image formation has been completed on one side from the upstream of the first discharge section to the upstream side of the image formation section in the main conveyance path And a second sub-transport path that guides the paper from the upstream side of the first discharge section in the main transport path to another second discharge section, and is discharged from the first discharge section. In an image forming apparatus that constitutes an image forming system by adding a post-processing device that performs post-processing on paper,
Condition determination means for determining whether the image forming condition is double-sided image formation in which images are formed on both sides of a sheet, the number of sheets constituting one copy is three or more, and the number of copies is two or more;
A paper feed delay necessity judging means for judging whether or not it is necessary to delay paper feed of the next part in order to perform post-processing of the previous part previously ejected in the transport plan;
The condition determination means determines that double-sided image formation is performed, and the number of sheets per copy is 3 or more and the number of copies is 2 or more. When it is determined that it is necessary to delay the paper feeding, the paper transport mechanism in the main transport path and the second sub transport path is controlled, and transported to the first discharge unit through the main transport path and discharged. The first sheet of the next part is guided from the first discharge part to the second sub-transport path and is temporarily retracted, and the retracted first sheet is then passed through the main transport path. And an overlap discharge control means for overlapping the second sheet of the next portion to be conveyed and discharged to the first discharge portion and discharging the two sheets simultaneously. apparatus. A paper supply unit storing paper, an image forming unit that forms an image on the paper, a first discharge unit that discharges the paper on which image formation has been performed in the image forming unit, and the image from the paper supply unit A main conveyance path for guiding the sheet to the first discharge section via the formation section, and a sheet on which image formation has been completed on one side from the upstream of the first discharge section to the upstream side of the image formation section in the main conveyance path And a second sub-transport path that guides the paper from the upstream side of the first discharge section in the main transport path to another second discharge section, and is discharged from the first discharge section. In an image forming apparatus that constitutes an image forming system by adding a post-processing device that performs post-processing on paper,
Condition determination means for determining whether the image forming condition is double-sided image formation in which images are formed on both sides of a sheet, the number of sheets constituting one copy is three or more, and the number of copies is two or more;
A paper feed delay necessity judging means for judging whether or not it is necessary to delay paper feed of the next part in order to perform post-processing of the previous part previously ejected in the transport plan;
An evacuation possibility judging means for judging whether or not the sheet can be evacuated to the first sub-conveying path in the conveyance plan;
The condition determination means determines that double-sided image formation is performed, and the number of sheets per copy is 3 or more and the number of copies is 2 or more. When it is determined that it is necessary to delay the sheet feeding, and the retractability determination unit determines that the sheet can be retracted, the main transport path, the first sub transport path, and the second sub transport path By controlling the paper transport mechanism, the first sheet of the next part that is transported and discharged to the first discharge part via the main transport path is discharged from the first discharge part to the second sub-transport path. The second sheet of the next part to be transported and discharged to the first discharge part through the main transport path and then discharged from the first discharge part to the first sub-transport. The first sheet and the second sheet that have been retracted are led to the path and retracted through the main transport path. An image forming apparatus comprising: an overlapped sheet discharge control unit that overlaps with the third sheet of the next section to be transported and discharged to the first discharge section and discharges three sheets simultaneously. .   The image forming apparatus according to claim 2, wherein the first sub-transport path and the second sub-transport path are partially shared on the upstream side of the first discharge unit.   The image forming apparatus according to claim 1, further comprising an image order adjusting unit that adjusts an image forming order in consideration of a stacking order of a plurality of sheets discharged in a superimposed manner. . A paper supply unit storing paper, an image forming unit that forms an image on the paper, a first discharge unit that discharges the paper on which image formation has been performed in the image forming unit, and the image from the paper supply unit A main conveyance path for guiding the sheet to the first discharge section via the formation section, and a sheet on which image formation has been completed on one side from the upstream of the first discharge section to the upstream side of the image formation section in the main conveyance path An image forming apparatus comprising: a first sub-transport path that guides a sheet; and a second sub-transport path that guides a sheet from an upstream side of the first discharge section in the main transport path to another second discharge section; In an image forming system comprising a post-processing device that performs post-processing on paper discharged from a section,
Condition determination means for determining whether the image forming condition is double-sided image formation in which images are formed on both sides of a sheet, the number of sheets constituting one copy is three or more, and the number of copies is two or more;
A paper feed delay necessity judging means for judging whether or not it is necessary to delay paper feed of the next part in order to perform post-processing of the previous part previously ejected in the transport plan;
The condition determination means determines that double-sided image formation is performed, and the number of sheets per copy is 3 or more and the number of copies is 2 or more. When it is determined that it is necessary to delay the paper feeding, the paper transport mechanism in the main transport path and the second sub transport path is controlled, and transported to the first discharge unit through the main transport path and discharged. The first sheet of the next part is guided from the first discharge part to the second sub-transport path and is temporarily retracted, and the retracted first sheet is then passed through the main transport path. And an overlap discharge control means for overlapping and discharging the second sheet of the next portion to be discharged after being conveyed to the first discharge portion. Forming system. A paper supply unit storing paper, an image forming unit that forms an image on the paper, a first discharge unit that discharges the paper on which image formation has been performed in the image forming unit, and the image from the paper supply unit A main conveyance path for guiding the sheet to the first discharge section via the formation section, and a sheet on which image formation has been completed on one side from the upstream of the first discharge section to the upstream side of the image formation section in the main conveyance path An image forming apparatus comprising: a first sub-transport path that guides a sheet; and a second sub-transport path that guides a sheet from an upstream side of the first discharge section in the main transport path to another second discharge section; In an image forming system comprising a post-processing device that performs post-processing on paper discharged from a section,
Condition determination means for determining whether the image forming condition is double-sided image formation in which images are formed on both sides of a sheet, the number of sheets constituting one copy is three or more, and the number of copies is two or more;
A paper feed delay necessity judging means for judging whether or not it is necessary to delay paper feed of the next part in order to perform post-processing of the previous part previously ejected in the transport plan;
An evacuation possibility judging means for judging whether or not the sheet can be evacuated to the first sub-conveying path in the conveyance plan;
The condition determination means determines that double-sided image formation is performed, and the number of sheets per copy is 3 or more and the number of copies is 2 or more. When it is determined that it is necessary to delay the sheet feeding, and the retractability determination unit determines that the sheet can be retracted, the main transport path, the first sub transport path, and the second sub transport path By controlling the paper transport mechanism, the first sheet of the next part that is transported and discharged to the first discharge part via the main transport path is discharged from the first discharge part to the second sub-transport path. The second sheet of the next part to be transported and discharged to the first discharge part through the main transport path and then discharged from the first discharge part to the first sub-transport. The first sheet and the second sheet that have been retracted are led to the path and retracted through the main transport path. An image forming system comprising: an overlapped sheet discharge control unit configured to overlap the third sheet of the next section to be conveyed and discharged to the first discharge section and to discharge three sheets simultaneously. .   The program for functioning a computer as each means in the image forming apparatus as described in any one of Claims 1-3.   A computer-readable recording medium on which the program according to claim 7 is recorded.

Images