JP2009145418A - Image forming device and image forming system, program, and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device and an image forming system, a program, and a recording medium capable of improving productivity in the image forming system constituted by providing the image forming device with a post-processing device. <P>SOLUTION: The image forming system is constituted by arranging a relay conveyance device 170 having a main conveyance passage 171 for conveying the paper delivered from the image forming device 100 into the post-processing device 150 and a detour conveyance passage 172 having larger length of conveyance passage than that of the main conveyance passage 171 between the image forming device 100 and the post-processing device 150. When printing job is continuously performed and supply and conveyance of paper for the next printing job are stopped to ensure post-processing time of the previous printing job, the conveyance passage in the relay conveyance device 170 is switched to the detour conveyance passage 172 having larger length of conveyance passage from the main conveyance passage 171. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  Processing performed after an image is formed on a sheet by an image forming apparatus such as a printer or a copier is generally referred to as “post-processing”. The details of the processing include stapling the paper (stapling), pinching the paper in half size (bookbinding processing), changing the paper discharge tray, and offsetting the discharge position. (Sorting process). The user can specify the type of post-processing in units of print jobs (image forming jobs) (see, for example, Patent Document 1).

  Such post-processing is performed by a post-processing apparatus attached to the image forming apparatus, and an image forming system is constructed by the image forming apparatus and the post-processing apparatus. For example, in the case of staple processing, when the last sheet of a print job is carried into the apparatus, the post-processing apparatus aligns the sheets, and then staples and discharges one place or a plurality of places.

  Here, the time required for the stapling process is determined by the position where stapling is performed, the number of stops, and the like, and also in the bookbinding process and the process of offsetting the discharge position, depending on conditions specified by the user.

  Then, in the case of a print job for which post-processing is designated, the image forming apparatus feeds paper (first and subsequent sheets) of the next print job in order to secure time for the post-processing apparatus to perform post-processing. The conveyance is stopped without performing the conveyance.

  That is, the image forming apparatus stops feeding and conveying the paper after printing on the last sheet of the previous print job, and then waits for the time required for the post-processing device to perform post-processing, and then In addition, sheet feeding (from the first sheet of the next print job) and conveyance are resumed.

In this specification, forming an image on a sheet is expressed as “printing” for convenience.
JP-A-11-10988

  Today, the processing speed (printing speed) of image forming apparatuses has been increased, and models in which the number of printed sheets per minute exceeds 100 have been commercialized.

  However, when an image forming system is provided by adding a post-processing device to such an image forming apparatus, as described above, the image forming apparatus feeds and conveys the paper during post-processing of the previous print job. And the printing on the paper for the next print job is not performed, so the productivity due to the increased processing speed cannot be improved as expected, and the productivity of the image forming system decreases. is there.

  The present invention has been made in view of the above problems, and provides an image forming apparatus, an image forming system, a program, and a recording medium that can improve productivity in an image forming system in which a post-processing device is attached to the image forming apparatus. It is an object.

  In order to solve the above problems, an image forming system according to the present invention includes an image forming apparatus for fixing an image printed on a sheet by a printing unit onto the sheet by a fixing unit, and a sheet discharged from the image forming apparatus. An image forming system comprising a post-processing device for performing post-processing, and controlling a sheet conveyance timing of a next print job so as to secure a post-processing time for the previous print job. As a conveyance path for conveying the paper discharged from the image forming apparatus to the post-processing apparatus, a switchable main conveyance path and a detour conveyance having a conveyance path length longer than the main conveyance path When a relay transport device having a path is arranged and it is necessary to delay the paper transport timing of the next print job in order to secure the post-processing time of the previous print job, Paper is transported The conveying path in the intermediary conveyance apparatus is characterized in that it comprises a bypass selection means for switching to the bypass transport path from the main transport path.

  In the above configuration, the image forming system is configured by adding the image forming apparatus and the post-processing apparatus, and the sheet of the next print job is secured in order to secure the post-processing time of the previous print job. An image forming system that controls the conveyance timing is assumed. As post-processing that needs to delay the next print job conveyance timing, for example, there is a stapling process in which paper is stapled.

  A relay conveyance device is attached between the image forming apparatus and the post-processing apparatus. The relay conveyance device includes a main conveyance path of a main conveyance path configured to be switchable as a conveyance path for conveying the paper discharged from the image forming apparatus to the post-processing apparatus, and a conveyance path that is more than the main conveyance path. A long detour conveyance path is provided. The paper discharged from the image forming apparatus is normally transported to the main transport path.

  In the above configuration, when the detour selection unit needs to delay the paper transport timing of the next print job in order to secure the post-processing time of the previous print job, the paper of the next print job Is switched from the main transport path to the detour transport path.

  Since the sheet is passed through the long detour conveyance path, the time until the sheet of the next print job arrives at the post-processing device is longer than that of the sheet conveyed on the short main conveyance path.

  As a result, if the time for paper arrival delay in the detour conveyance path is longer than the post-processing time, the image forming apparatus continues the printing operation without delaying the paper conveyance timing of the next print job. This can increase the productivity of the image forming system.

  Further, even when the time when paper arrival is delayed in the detour conveyance path is shorter than the post-processing time, the time for delaying the conveyance timing can be shortened, so that the productivity of the image forming system can be increased.

  Moreover, it is preferable that the detour conveyance path has a U shape. By adopting the U shape, a long conveyance path length can be easily ensured in the occupied space of the main conveyance path extending linearly.

  Further, in the present image forming system, the detour conveyance path includes a plurality of detour conveyance paths having different lengths, and the detour selection unit includes a plurality of detour conveyance based on a time for delaying the conveyance timing. It can also be set as the structure which selects any one of the paths.

  The post-processing time varies depending on the content of processing, but a long detour conveyance path that delays the arrival of paper to the post-processing apparatus more than necessary also causes a decrease in productivity.

  According to this, a plurality of detour conveyance paths having different lengths are provided as detour conveyance paths, and the detour selection means selects one of the plurality of detour conveyance paths based on the time for delaying the conveyance timing. Therefore, it is possible to select a conveyance path length corresponding to the post-processing time, and the productivity of the image forming system can be improved more efficiently.

  In the image forming system of the present invention, the bypass route selection unit may further delay the transport timing of the next print job in a state where the bypass transport path has already been used for transporting the paper. If there is a detour conveyance path that is longer than the detour conveyance path that is being used, a longer detour conveyance path may be selected as the conveyance path for conveying the sheet of the next print job.

  According to this, even if a print job requiring post-processing continues, if there is a detour conveyance path that is longer than the detour conveyance path in use, this longer detour conveyance path is the next post-print job. Is used for transporting the paper, and a post-processing time is secured.

  Therefore, in the case of post-processing with a relatively short post-processing time, it is possible to improve the productivity of the image forming system more efficiently by making the most of a plurality of detour conveyance paths.

  In the image forming system of the present invention, when it is necessary to delay the sheet conveyance timing of the next print job in order to secure the post-processing time of the previous print job, at least the relay conveyance device and A configuration is provided that includes an inter-sheet enlargement unit that increases the conveyance speed of the sheet in the post-processing device above a specified speed and increases the distance between the last sheet of the previous print job and the first sheet of the next print job. You can also.

  Increasing the length of the detour conveyance path leads to an increase in the size of the relay conveyance apparatus and the length of the main conveyance path itself, so that the length that the detour conveyance path can take is limited to some extent.

  In the above configuration, when it is necessary for the inter-paper enlarging means to delay the paper conveyance timing of the next print job in order to secure the post-processing time of the previous print job, at least the relay conveyance device and The conveyance speed of the paper in the post-processing device is increased above a specified speed so as to increase the distance between the last paper of the previous print job and the first paper of the next print job.

  Therefore, the gap between the expanded sheet between the last sheet of the previous print job and the first sheet of the next print job, which is made by increasing the sheet conveyance speed of the previous print job, is determined. Can be used for post-processing of the previous print job.

  Accordingly, the post-processing time that can be ensured without delaying the conveyance timing is longer than the configuration corresponding to only the detour conveyance path, and the required length of the detour conveyance path can be shortened.

  In the image forming system of the present invention, the conveyance path is further switched to a shorter detour conveyance path or main conveyance path between sheets spread due to a delay in the discharge timing of the sheet from the image forming apparatus. It is preferable to have a configuration including one return means.

  The detour conveyance path is curved to ensure a long conveyance path length in a limited space, and the sheet is also conveyed in a curved state. Therefore, it can be said that the longer the detour conveyance path is, the more likely the jam is to occur, and it is preferable that the detour conveyance path is quickly returned to the main conveyance path.

  In the above-described configuration, the first return means switches and returns the conveyance path to the shorter detour conveyance path or the main conveyance path between the sheets spreading due to the delay of the discharge timing of the sheet from the image forming apparatus.

  The situation in which the paper discharge timing from the image forming apparatus is delayed may include a case where it takes time to print on the next paper due to a jam or out of paper in the image forming apparatus, or between a print job and a print job. This is the case where there is more time (feeding distance between sheets) before the next sheet is fed and transported than when continuous printing is performed on each sheet included in the same print job.

  As a result, the occurrence of a jam caused by using the detour conveyance path can be reduced, and the productivity of the image forming system can be further increased.

  Further, in the image forming system of the present invention, at least the paper transport speed in the relay transport device and the post-processing device is increased above a specified speed, and the paper transported in the relay transport device and then the relay transport It is also possible to increase the distance from the sheet carried into the apparatus and to include a second return means for switching the conveyance path to a shorter detour conveyance path or main conveyance path between spread sheets.

  According to the above configuration, the second return unit raises the sheet conveyance speed at least in the relay conveyance apparatus and the post-processing apparatus above the specified speed, the sheet conveyed in the relay conveyance apparatus, and then the relay conveyance apparatus The distance to the sheet transported to is increased, and the transport path is switched back to a shorter detour transport path or main transport path between the spread sheets.

  Therefore, since the distance between the paper transported in the relay transport device and the paper next transported into the relay transport device is increased, the timing of switching the transport path is positively made to return the transport path, so the first return It is possible to return to the main transport path more quickly than the configuration including only the means, and it is possible to more effectively reduce the jam problem caused by using the detour transport path.

  In order to solve the above problems, an image forming apparatus of the present invention is an image forming apparatus in which an image printed on a sheet by a printing unit is fixed on a sheet by a fixing unit, and is discharged from the image forming apparatus. An image for controlling the paper transport timing of the next print job in order to secure the post-processing time of the previous print job by configuring an image forming system by adding a post-processing device that performs post-processing on the paper. In the forming apparatus, a switchable main transport path and the main transport path are transported between the image forming apparatus and the post-processing apparatus as transport paths for transporting the paper discharged from the image forming apparatus to the post-processing apparatus. It is possible to attach a relay conveyance device with a detour conveyance path whose conveyance path length is longer than the conveyance path, and to ensure the sheet conveyance timing of the next print job in order to secure the post-processing time of the previous print job. Need to be delayed In some cases, the conveyance path in the intermediary conveyance device the sheet for the next print job is conveyed, is characterized in that it comprises a bypass selection means for switching to the bypass transport path from the main transport path.

  As already described as an image forming system, the image forming apparatus of the present invention is provided with the relay conveying apparatus of the present invention and the conventional post-processing apparatus to configure the image forming system, thereby achieving higher productivity. The image forming system can be realized.

  In order to solve the above-described problem, the relay conveyance device according to the present invention provides an image forming apparatus that fixes an image printed on a sheet by a printing unit onto the sheet by a fixing unit, and a sheet discharged from the image forming apparatus. A switchable main transport path and a main transport path that are arranged between the post-processing apparatus that performs post-processing and transport the paper discharged from the image forming apparatus to the post-processing apparatus. And a detour conveyance path having a long conveyance path length.

  As already described as an image forming system, the relay transport apparatus having such a configuration, together with the conventional post-processing apparatus, is attached to the image forming apparatus of the present invention to configure the image forming system. An image forming system having the characteristics can be realized.

  Furthermore, the present invention includes a program for causing a computer to function as each unit in the above-described image forming system of the present invention and a computer-readable recording medium on which the program is recorded.

  That is, each unit in the image forming system may be realized by hardware, or may be realized by causing a computer to execute a program. 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 operates as each unit in the image forming system. Accordingly, the same effects as the respective units, the discharge delay detecting unit, and the conveyance path returning unit in the image forming system are obtained.

  In the image forming system of the present invention, as described above, the conveyance path for conveying the paper discharged from the image forming apparatus to the post-processing apparatus is provided between the image forming apparatus and the post-processing apparatus. A relay transport device having a switchable main transport path and a detour transport path having a transport path length longer than the main transport path is arranged, and the next transport job is secured to secure the post-processing time of the previous print job. When it is necessary to delay the paper transport timing of a print job, the relay transport device that transports the paper of the next print job without delaying the transport timing or shortening the delay time Is provided with detour selection means for switching the main conveyance path from the main conveyance path to the detour conveyance path.

  As a result, according to the image forming system of the present invention, there is an effect that it is possible to realize an image forming system with high productivity without wasting the high capability of the image forming apparatus that has been speeded up.

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

  First, the overall configuration of an image forming system according to an embodiment of the present invention will be described. FIG. 2 is a schematic diagram illustrating the overall configuration of the image forming system according to the present embodiment. This image forming system includes an image forming apparatus 100, a relay conveying apparatus 170, and a post-processing apparatus 150.

  The image forming apparatus 100 acquires image data read from a document, or acquires image data received from the outside, and converts a monochrome image indicated by the image data onto a sheet (recording material, sheet). The configuration is roughly divided into a document transport unit 101, an image reading unit 102, a printing unit 103, a paper transport unit (paper transport unit) 104, and a paper feed unit 105.

  When at least one document is set on the document set tray 11 in the document transport unit 101, the document is pulled out and transported one by one from the document set tray 11, and this document is transported to the document reading window 102 a of the image reading unit 102. The document is guided and passed, and the document is discharged to the discharge tray 12.

  A CIS (Contact Image Sensor) 13 is disposed above the document reading window 102a. When the document passes through the document reading window 102a, the CIS 13 repeatedly reads the image on the back side of the document in the main scanning direction, and outputs image data indicating the image on the back side of the document.

  Further, the image reading unit 102 exposes the surface of the document by the lamp of the first scanning unit 15 when the document passes through the document reading window 102a, and from the document surface by the mirrors of the first and second scanning units 15 and 16. The reflected light is guided to the imaging lens 17, and an image of the document surface is formed on a CCD (Charge Coupled Device) 18 by the imaging lens 17. The CCD 18 repeatedly reads the image on the document surface in the main scanning direction, and outputs image data indicating the image on the document surface.

  Further, when the document is placed on the platen glass on the upper surface of the image reading unit 102, the first and second scanning units 15 and 16 are moved while maintaining a predetermined speed relationship with each other. The document surface on the platen glass is exposed, the reflected light from the document surface is guided to the imaging lens 17 by the first and second scanning units 15 and 16, and the image on the document surface is connected to the CCD 18 by the imaging lens 17. Image.

  The image data output from the CIS 13 or the CCD 18 is subjected to various image processing by a control circuit such as a microcomputer and then output to the printing unit 103.

  The printing unit 103 records a document image indicated by image data on a sheet, and includes a photosensitive drum 21, a charger 22, an optical writing unit 23, a developing unit 24, a transfer unit 25, a cleaning unit 26, and a fixing unit. A unit 27 and the like are provided.

  The photosensitive drum 21 rotates in one direction, and after the surface is cleaned by the cleaning unit 26, the surface is uniformly charged by the charger 22. The charger 22 may be of a charger type or of a roller type or a brush type that contacts the photosensitive drum 21.

  The optical writing unit 23 is a laser scanning unit (LSU) including two laser irradiation units 28a and 28b and two mirror groups 29a and 29b. In the optical writing unit 23, image data is input, laser light corresponding to the image data is emitted from the laser irradiation units 28a and 28b, and the laser light is transmitted through the mirror groups 29a and 29b. The drum 21 is irradiated to expose the uniformly charged surface of the photosensitive drum 21 to form an electrostatic latent image on the surface of the photosensitive drum 21.

  The optical writing unit 23 employs a two-beam method including two laser irradiation units 28a and 28b in order to cope with high-speed printing processing, thereby reducing the burden associated with increasing the irradiation timing.

  As the optical writing unit 23, an EL writing head or LED writing head in which light emitting elements are arranged in an array can be used instead of the laser scanning unit.

  The developing device 24 supplies toner to the surface of the photosensitive drum 21 to develop the electrostatic latent image, and forms a toner image on the surface of the photosensitive drum 21. The transfer unit 25 transfers the toner image on the surface of the photosensitive drum 21 onto the sheet conveyed by the sheet conveying unit 104.

  The fixing unit 27 heats and pressurizes the paper to fix the toner image on the paper. Thereafter, the sheet is further conveyed to the sheet discharge tray 47 by the sheet conveying unit 104 and discharged. The cleaning unit 26 removes and collects the toner remaining on the surface of the photosensitive drum 21 after development and transfer.

Here, the transfer unit 25 includes a transfer belt 31, a drive roller 32, a driven roller 33, an elastic conductive roller 34, and the like, and the transfer belt 31 is stretched between the rollers 32 to 34 and other rollers. Rotating. The transfer belt 31 has a predetermined resistance value (for example, 1 × 10 ⁹ to 1 × 10 ¹³ Ω / cm), and conveys the paper placed on the surface thereof. The elastic conductive roller 34 is pressed against the surface of the photosensitive drum 21 via the transfer belt 31, and presses the sheet on the transfer belt 31 against the surface of the photosensitive drum 21. An electric field having a polarity opposite to the charge of the toner image on the surface of the photosensitive drum 21 is applied to the elastic conductive roller 34, and the toner image on the surface of the photosensitive drum 21 is transferred onto the transfer belt 31 by the electric field having the opposite polarity. It is transferred to the paper. For example, when the toner image has a charge of (−) polarity, the polarity of the electric field applied to the elastic conductive roller 34 is set to (+) polarity.

  The fixing unit 27 includes a heating roller 35 and a pressure roller 36. A heat source for setting the surface of the heating roller 35 to a predetermined temperature (fixing temperature: approximately 160 to 200 ° C.) is provided inside the heating roller 35. In addition, pressure members (not shown) are arranged at both ends of the pressure roller 36 so that the pressure roller 36 is pressed against the heating roller 35 with a predetermined pressure. When the sheet is conveyed to a pressure contact portion (referred to as a fixing nip portion) between the heating roller 35 and the pressure roller 36, the unfixed toner image on the sheet is conveyed while the sheet is conveyed by the rollers 35 and 36. The toner image is fixed on the paper by being heated and melted and pressurized.

  The sheet conveyance unit 104 includes a main conveyance path 43, a reverse conveyance path 44, a plurality of branching claws 45, a plurality of pairs of conveyance rollers 41 for conveying sheets arranged in each conveyance path, a pair of registration rollers 42, and a pair of registration rollers 42 The sheet discharge roller 46 is provided.

  The main conveyance path 43 is a conveyance path extending from the paper feeding unit 105 to the paper discharge roller 46. The sheet conveying unit 104 receives the sheet from the sheet feeding unit 105 and conveys the sheet until the leading end reaches the registration roller 42. At this time, since the registration roller 42 is temporarily stopped, the leading edge of the sheet reaches and contacts the registration roller 42, and the sheet is bent. The leading edge of the sheet is aligned parallel to the registration roller 42 by the elastic force of the bent sheet. Thereafter, rotation of the registration roller 42 is started, and the registration roller 42 conveys the sheet to the transfer unit 25 of the printing unit 103, and reaches the fixing unit 27.

  The registration roller 42 is stopped and rotated by switching on and off the clutch between the registration roller 42 and the drive shaft, or by switching on and off the motor that is the drive source of the registration roller 42.

  Further, the reverse conveyance path 44 is branched from the main conveyance path 43. FIG. 4 shows an enlarged view of a main part of the reverse conveyance path 44. The reverse conveyance path 44 includes an upper conveyance path 44-2 connected to the registration roller 42, and a lower conveyance path 44-1 disposed below the upper conveyance path 44-2.

  A branching claw 45 is provided at each branch point of the upper and lower transport paths 44-2 and 44-1 in the main transport path 43 and the reverse transport path 44.

  In the case of double-sided printing, the paper transport unit 104 rotates the plurality of branch claws 45 to switch the branch path between the main transport path 43 and the reverse transport path 44, and allows the paper that has passed through the fixing unit 27 to pass through the reverse transport path 44. It is temporarily pulled into the lower conveyance path 44-1. Then, after the trailing edge of the sheet passes through the conveyance roller 41b, the conveyance roller 41h is rotated in the reverse direction to switch back the sheet, and return to the registration roller 42 in the main conveyance path 43 again through the upper conveyance path 44-2. As a result, an image is also recorded on the back side of the sheet. After the images are formed on both sides, the sheet that has passed through the fixing unit 27 is discharged to the outside of the image forming apparatus 100 by the discharge roller 46 through the main conveyance path 43.

  Also, in the case of single-sided printing, the paper transport unit 104 rotates the plurality of branch claws 45 to switch the branch path between the main transport path 43 and the reverse transport path 44, and the paper that has passed through the fixing unit 27 is reverse transport path. 44 is temporarily pulled into the lower conveyance path 44-1. Then, after the trailing edge of the sheet passes through the conveying roller 41a, the conveying rollers 41b and 41h are rotated in reverse to switch back the sheet, return to the main conveying path 43, and be discharged to the outside of the image forming apparatus 100 by the discharge roller 46. And eject the paper. As a result, a sheet that is face-up discharged when discharged straight is discharged face-down.

  In the main transport path 43 and the reverse transport path 44, sensors for detecting the position of the paper and the like are arranged in various places, and the transport roller 41 and the registration roller 42 are driven and controlled based on the position of the paper detected by each sensor. The paper is transported and positioned. Note that the paper transport mechanism of the image forming apparatus 100 includes a plurality of transport rollers and paper discharge rollers 46 provided on a transport path in the image forming apparatus 100.

  The paper feed unit 105 includes a plurality of paper feed trays 51. Each paper feed tray 51 is a tray for storing sheets, and is provided below the image forming apparatus 100. Each paper feed tray 51 is provided with a pick-up roller or the like for pulling out the paper one by one, and sends out the pulled paper to the main transport path 43 of the paper transport unit 104.

  Since the image forming apparatus 100 of the present embodiment is intended for high-speed printing processing, each of the paper feed trays 51 has a capacity capable of storing 500 to 1500 standard size sheets.

  Further, a manual feed tray 53 for mainly supplying irregular-size paper is provided on the side surface of the image forming apparatus 100. In addition, as indicated by a broken line in the drawing, a large-capacity paper feed cassette (LCC) 52 capable of storing a large amount of a plurality of types of sheets can be disposed on the side surface of the image forming apparatus 100.

  On the other hand, on the side surface opposite to the manual feed tray 53 in the image forming apparatus 100, a paper discharge tray is usually provided. A post-processing device 150 that performs processing, and a relay conveyance device 170 that connects the post-processing device 150 and the image forming apparatus 100 are arranged.

  That is, in the present embodiment, the relay conveyance device 170 is disposed on the downstream side of the main body side discharge roller 46 in the image forming apparatus 100, and the post-processing device 150 having the staple unit 153 mounted thereon is further mounted on the downstream side. Has been.

  The post-processing device 150 has a paper carry-in port 155 at a position corresponding to the paper discharge port of the image forming apparatus 100 and also corresponding to the paper discharge port 177 of the relay transfer device 170. A first pair of transport rollers 156 is disposed at the paper carry-in entrance 155.

  The paper discharged from the relay conveyance device 170 is carried into the post-processing device 150 from the paper carry-in port 155 and conveyed to the staple processing conveyance path 157 or the through conveyance path 158 provided with a plurality of pairs of conveyance rollers 156. The

  The staple processing conveyance path 157 is provided with the staple unit 153. The sheets for one job are stacked in the order of discharge, and when sheets for one job are stacked, the staple unit 153 staples them into one bundle, and then discharges them onto the discharge tray 151 by the discharge rollers 159. Paper. On the other hand, the sheets conveyed to the through conveyance path 158 are sequentially discharged onto the sheet discharge tray 152 by the sheet discharge roller 160.

  On the other hand, the relay conveyance device 170 has a paper carry-in port 175 at a position corresponding to the paper discharge port of the image forming apparatus 100, and a first pair of carry rollers 176 a is disposed at the paper carry-in port 175. Yes. The paper discharged from the image forming apparatus 100 is carried into the relay conveyance device 170 from the paper carry-in entrance 175.

  Further, the paper transport mechanism of the post-processing device 150 is configured by a plurality of transport rollers provided in a transport path in the post-processing device 150.

  FIG. 5 shows a detailed view of the relay transfer device 170. In FIG. 5, the relay conveyance device 170 and the post-processing device 150 are shown as one unit, but the image forming apparatus 100, the post-processing device 150, and the relay conveyance device 170 Each may be unitized.

  A main transport path 171 and a U-shaped detour transport path 172 are provided on the downstream side of the first transport roller 176a in the relay transport apparatus 170. The main transport path 171 linearly extends to a transport roller 176g provided in the vicinity of the paper discharge port 177, and the detour transport path 172 extends to the transport roller 176g in a U-shaped manner. A first gate 173 a is disposed at a branch point between the main conveyance path 171 and the detour conveyance path 172. The sheet discharged from the image forming apparatus 100 is conveyed to either the main conveyance path 171 or the detour conveyance path 172 according to the guidance of the first gate 173a.

  In the detour conveyance path 172, first and second detour conveyance paths 172a and 172b having different lengths are configured by branching two places along the middle of the third detour conveyance path 172c having the longest conveyance path length. Yes. The first bypass transport path 172a branched first is the shortest transport path length, and the second bypass transport path 172b branched second is the transport path length of the first bypass transport path 172a and the third bypass transport path 172a. It is in the middle of the detour conveyance path 172c. A plurality of transport rollers 176b to 176f are arranged on each of the first to third detour transport paths 172a to 172c.

  The second and third gates 173b and 173c are arranged at the two branch points, and the sheet guided to the detour conveyance path 172 is fed to the second and third gates 173b and 173c. Following the guidance, the sheet is conveyed to any one of the first to third detour conveyance paths 172a to 172c.

  The relay transfer device 170 is controlled by a sub central processing unit 201 of the machine control board 200 described later, and the central processing unit 201 has a main transfer path 171 and first to third detour transfer paths 172a. It is determined as will be described later which of the transport paths of ˜172c is to be used.

  In addition, the paper transport mechanism of the relay transport device 170 is configured by a plurality of transport rollers 176a to 176g provided in the transport path in the relay transport device 170, and the switching mechanism of the relay transport device 170 is in the relay transport device 170. The plurality of first to third gates 173a to 173c provided in the transfer path.

  Next, a control system of the image forming system according to the embodiment of the present invention will be described. FIG. 3 is an overall block configuration diagram of various unit units, image processing units, and the like constituting the image forming system of the present embodiment, and each unit unit is operated by a main central processing unit 401 (CPU) positioned substantially at the center. It is a figure which shows the state which is managing operation | movement, taking cooperation with the sub central processing unit (CPU) mounted for every.

  As can be seen from FIG. 3, an operation panel board 700 for managing and controlling the operation panel 703, which is roughly located at the upper right of the drawing, and a machine for managing and controlling the units constituting the image forming apparatus 100, which are located at the upper left of the drawing. A control board 200, a CCD board 300 that electrically reads a document image that is electronic data and is located at the lower left of the drawing, and electronic data that is converted into electronic data by the CCD board 300 that is located at the center of the drawing. A main image processing board 400 that performs predetermined image processing, a sub image processing board 500 that further performs predetermined image processing on image information processed by the main image processing board 400, and a lower right portion of the drawing. Other extensions connected to the sub-image processing board 500 via an interface Over de group 600 (printer board 601, fax board 603, the function expansion board 602) and a like.

The contents managed and controlled for each board will be described below.
(Operation panel board 700)
The operation panel board 700 is basically controlled by a sub central processing unit (CPU) 701, and operation keys for inputting instructions relating to the display screen of the LCD display unit 704 disposed on the operation panel 703 and various modes. An operation input or the like is managed from the group 705.

  A memory 702 for storing various control information on the operation panel such as data input from the operation key group 705 and information to be displayed on the LCD screen of the LCD display unit 704 is provided.

  In this configuration, the sub central processing unit (CPU) 701 performs control data communication with the main central processing unit (CPU) 401 and instructs the image forming apparatus 100 to operate.

Further, the main central processing unit 401 transfers a control signal indicating the operation state of the image forming apparatus 100 to the sub central processing unit (CPU) 701, thereby passing through the LCD display unit 704 of the operation panel 703. The operating state is displayed to the operator as to what state the apparatus is currently in.
(Machine control board 200)
The machine control board 200 is entirely controlled by a sub central processing unit 201, and includes a document conveying unit 101 such as ADF / RADF, an image reading unit 102 that reads a document image, and a printing unit 103 that reproduces image data as an image. A sheet feeding unit 105 that sequentially feeds sheets on which images are recorded from the sheet feeding tray 51 and the like, and sequentially feeds the fed sheets toward the printing unit 103, and images are recorded on the printing unit 103. A paper transport unit 104 and the like that controls the paper to be fed back to the paper discharge roller by being turned upside down or switched back are managed.

  The post-processing device 150 and the relay transfer device 170 described above are also managed by the sub central processing unit 201 of the machine control board 200.

Specifically, among these, the document conveyance unit 101 and the post-processing device 150 are provided with their own central processing units 203a and 150a, and communicate with the central processing unit 201 so as to be unique. I have control.
(CCD board 300)
The CCD board 300 includes a CCD 18 for electrically reading a document image, a circuit (CCD gate array) 302 for driving the CCD 18, an analog circuit 303 for adjusting gain of analog data output from the CCD 18, and an analog output of the CCD 18. An A / D converter 304 that converts it into a digital signal and outputs it as electronic data, and the like, is controlled by the main central processing unit 401.
(Main image processing board 400)
The main image processing board 400 is controlled by the main central processing unit 401, a multi-value image processing unit 402, a memory 403 for storing various control information such as processed image data or processing procedure management, and processing In order to reproduce an image with the image information subjected to, a laser control unit 404 that controls transfer of data to the optical writing unit 23 side and the like are included.

The multi-value image processing unit 402 performs shading correction, density correction, and area correction so that the gradation of the image can be expressed in a desired state based on the electronic data of the original image sent from the CCD board 300. Processing such as separation, filter processing, MTF correction, resolution conversion, electronic zoom (magnification processing), and gamma correction is performed in the state of multivalued image data.
(Sub image processing board 500)
The sub image processing board 500 is connected to the main image processing board 400 by a connector, and is controlled by the main central processing unit 401 on the main image processing board 400. The binary image processing unit 501 and the image processed 2 are processed. A memory for storing and managing value image data or control information for processing, a gate array 502 for controlling the memory, and storing and managing a plurality of document image information, and repeating a plurality of document images to the desired number of copies A hard disk for reading out only a plurality of copies, a gate array 503 for controlling the hard disk, a gate array 504 for controlling SCSI and SCSI as an external interface, and the like.

The binary image processing unit 501 includes a processing unit that converts multi-valued image data into a binary image, a processing unit that rotates an image, and a binary scaling (zoom) processing unit that performs scaling processing of a binary image. Further, a fax interface is provided so that a fax image can be transmitted and received via the communication means.
(Expansion board 600)
The expansion board 600 extends the editing function of the printer board 601 and the image forming apparatus 100 for enabling data sent from a personal computer or the like to be output as a printer mode from the printing unit 103 of the image forming apparatus 100. The function expansion board 602 for effectively utilizing the features of the forming apparatus 100, the original image read from the image reading unit 102 of the image forming apparatus 100 is transmitted to the other party, and the image information sent from the other party is received. There is a fax board 603 that enables output from the printing unit 103 of the image forming apparatus 100.

In the following, the image processing apparatus of the image forming apparatus 100 will be described in more detail with respect to copy, fax, image data processing in the printer mode, and the flow of image data.
(Copy mode)
Documents set at a predetermined position of the document conveying unit 101 of the image forming apparatus 100 are sequentially supplied one by one to the document reading window 102a of the image reading unit 102, and images of the document are sequentially transferred to the CCD 18 or the CIS 13 described above. It is read and transferred to the main image processing board 400 as, for example, 8-bit electronic data.

  The 8-bit electronic data transferred to the main image processing board 400 is subjected to predetermined processing on the multi-value image processing unit 402 as 8-bit electronic image data. The 8-bit electronic image data is subjected to processing such as gamma correction and sent to the optical writing unit 23 composed of LSU via the laser control unit 404.

As a result, the document image read by the image reading unit 102 of the image forming apparatus 100 is output from the printing unit 103 as a copy image having gradation.
(Electronic RDH function in copy mode)
Similarly, the originals set at predetermined positions of the original conveying unit 101 of the image forming apparatus 100 are sequentially supplied one by one to the original reading window 102a of the image reading unit 102, and the original image is supplied to the CCD 18 or the CIS 13 described above. The data is sequentially read and transferred to the main image processing board 400 as, for example, 8-bit electronic data.

  The 8-bit electronic data transferred to the main image processing board 400 is subjected to predetermined processing on the multi-value image processing unit 402 as 8-bit electronic image data.

  The 8-bit electronic image data is then sent from the connector 405 on the main image processing board 400 side to the sub image processing board 500 side via the connector 505 on the sub image processing board 500 side, and a binary image processing unit. The multi-value binary conversion unit 501 converts 8-bit electronic image data into 2-bit electronic image data together with processing such as error diffusion.

  The reason why the 8-bit electronic image data is converted into 2-bit electronic image data including processing such as error diffusion is that there is a problem in image quality only by performing multi-value binary conversion. Therefore, consideration is given to reducing deterioration in image quality. The reason why the 8-bit electronic image data is converted into 2-bit electronic image data is that the storage capacity of the image is taken into consideration.

  The 2-bit electronic image data converted in this way is transferred to a disk memory 503 such as a hard disk for each document and temporarily stored and managed.

  When all the document groups set at a predetermined position of the document conveying unit 101 of the image forming apparatus 100 are read, the 2-bit electronic image data temporarily stored in the hard disk 503 is designated by the control of the gate array. The read 2-bit electronic image data is repeatedly sent to the main image processing board 400 via the connector connection portions 405 and 505, and subjected to processing such as gamma correction and laser control. It is sent to the optical writing unit 23 via the unit 404.

  Here, it has been described that all the images of the document group are read and then the image group is repeatedly read by the desired number of copies. However, the image output of the first copy is a stage where a predetermined number of images have been prepared. It is also possible to configure so as to output sequentially.

As a result, the document image read by the image reading unit 102 of the image forming apparatus 100 is output from the printing unit 103 as a copy image having gradation.
(Printer mode)
Image data sent from a network-connected external device such as a personal computer is developed on the board 601 as a page unit image on the printer board 601, and then once from the SCSI 504 serving as an interface to the sub image processing board 500 side. And stored in a memory such as the hard disk 503.

  Note that image data developed as a page image on the printer board 601 is sent to the sub-image processing board 500 side, but binary image processing is not performed on the page image, but only temporarily stored in the hard disk 503.

  Also, when a page image once stored is read from the hard disk 503, binary image processing is not performed on the page image.

Then, the image data temporarily stored in the hard disk 503 is sent to the main image processing board 400 while being read from the hard disk 503 so as to be in a predetermined page order, and subjected to gamma correction. Image writing is controlled by the writing unit 23 to reproduce the image.
(Fax mode)
The fax mode includes processing for sending a document to a destination and receiving a document from the destination.

  First, the transmission of a document to the other party will be described. The transmission originals set at a predetermined position of the original conveying unit 101 of the image forming apparatus 100 are sequentially supplied one by one to the original reading window 102a of the image reading unit 102, and the original image is supplied to the CCD 18 or the CIS 13 described above. The data is sequentially read and transferred to the main image processing board 400 as, for example, 8-bit electronic data.

  The 8-bit electronic data transferred to the main image processing board 400 is subjected to predetermined processing on the multi-value image processing unit 402 as 8-bit electronic image data.

  The 8-bit electronic image data is then sent from the connector 405 on the main image processing board 400 side to the sub image processing board 500 side via the connector 505 on the sub image processing board 500 side, and a binary image processing unit. The multi-value binary conversion unit 501 converts 8-bit electronic image data into 2-bit electronic image data together with processing such as error diffusion so as to reduce image quality degradation.

  The transmission original converted into a binary image in this way is compressed in a predetermined format and stored in the memory 502.

  When the transmission procedure with the other party is performed and a state where transmission is possible is ensured, the image data of the transmission document compressed in a predetermined format read from the memory 502 is transferred to the fax board 603 side, Necessary processing such as changing the compression format is performed on the fax board 603, and the fax is sequentially transmitted to the other party via a communication line.

  Next, processing of a document image transmitted from the other party will be described. When the document image data is transmitted from the other party through the communication line, the document image data transmitted from the other party is received while performing the communication procedure with the fax board 603 and is compressed into a predetermined format. The received image data in such a state is sent from the fax interface provided in the binary image processing unit 501 of the sub image processing board 500 to the binary image processing unit 501 and transmitted as a page image by the compression / decompression processing unit or the like. Reproduce the original image.

  Then, the original image reproduced as a page-by-page image is transferred to the main image processing board 400 side to perform gamma correction, and image writing is controlled so that the optical writing unit 23 reproduces the image from the laser control unit 404. Is done.

  The image forming apparatus 100 constituting the image forming system realizes a printing speed of 100 sheets / min. Of single-sided printing with, for example, A4 lateral feed (paper conveyance direction is the paper short direction). In order to realize such a printing speed, in the image forming apparatus 100, the sheet conveyance speed is set to a different value in the partial portion.

  Explaining numerical values as examples, if the process speed of the image forming apparatus 100 (also the peripheral speed of the photosensitive drum 21) is 540 mm / second, the conveyance speed of the sheet from the registration roller 42 to the fixing unit 27 is The process speed is set to 540 mm / sec. On the other hand, the sheet conveyance speed from the sheet feeding tray 51 to the registration roller 42 is set to, for example, 600 mm / second, which is faster than the process speed, and the sheet is rapidly conveyed to the registration roller 42. It is like that.

  Further, the sheet conveyance speed in the reverse conveyance path 44 is also set to a speed different from the process speed. For example, the paper after passing through the fixing unit 27 during double-sided printing is switched back and returned to the registration roller 42, and the paper after passing through the fixing unit 27 during single-sided printing is switched back and discharged face-down. Both the paper conveyance speeds in the conveyance path are set to 1000 mm / second. As a result, the paper can be quickly switched back and guided to the printing unit 103 or the paper discharge roller 46.

  However, as described above, no matter how the speed of the image forming apparatus 100 is increased, if the post-processing device 150 is added to constitute the image forming system, the post-processing time for the previous print job can be secured. The image forming apparatus 100 stops paper feeding and conveyance. As a result, there is a problem that the ability of the image forming apparatus 100 cannot be fully utilized, and productivity as an image forming system is lowered.

  In the image forming system of this embodiment, in order to solve this problem, the above-described relay transfer device 170 including the detour transfer path 172 is disposed between the image forming apparatus 100 and the post-processing device 150. . If it is necessary to delay the paper transport timing of the next print job in order to secure the post-processing time of the previous print job, the transport path for transporting the paper of the next print job is By passing the detour conveyance path 172 having a long conveyance path length, the arrival of the sheet at the post-processing apparatus 150 is delayed and the post-processing time is secured.

  Such switching of the transport path is performed by the bypass selection means 210 in FIG. The bypass selection unit 210 transports the sheet of the next print job when it is necessary to delay the sheet transport timing of the next print job in order to secure the post-processing time of the previous print job. The path is switched from the main transport path 171 to the detour transport path 172.

  FIG. 1 shows a functional block diagram around the detour selection means 210. The detour selection unit 210 includes a continuity determination unit 211, a post-processing determination unit 212, and a detour selection unit 213.

  The continuity determination unit 211 determines whether a print job continues when a new print job occurs. Whether or not it is continuous can be determined by whether or not there is a print job to be processed before a new print job. When a new print job is generated during processing of a print job, the continuity determination unit 211 determines that the new print job is in a state where the print job is continuously performed. Further, even when a plurality of print jobs are received in a process waiting state and are in a state of being sequentially processed, it is determined that a print job is continuously performed for each of the print jobs waiting for processing.

  The post-processing determination unit 212 determines whether or not post-processing is specified for the print job processed immediately before when the print job is continuously performed. If it is determined that post-processing is designated, it is determined that it is necessary to delay the sheet conveyance timing of the newly generated print job. Here, the post-processing determination unit 212 also acquires time information for delaying the conveyance timing corresponding to the post-processing time from the content of the post-processing. The contents of the post-processing can be grasped from the control information attached to the head of the image data of the previous print job. For example, by referring to a table in which the post-processing time is stored in association with the contents of the post-processing . Can be acquired easily.

  Such a continuity determination unit 211 and a post-processing determination unit 212 may be the single central processing unit 201 of the machine control board 202 shown in FIG. 3 or the central processing of the central processing unit 201 and the post-processing unit 150. It is comprised with the apparatus 150a. When the central processing unit 201 has a table or the like in which the post-processing time is stored, the central processing unit 201 can be configured independently. When the central processing unit 150a of the post-processing unit 150 has, the central processing unit 201 and the central processing unit 150a of the post-processing device 150.

  When the post-processing determination unit 212 determines that the conveyance timing needs to be delayed when processing a newly generated print job, the post-processing determination unit 212 notifies the detour selection unit 213 together with information on the time to be delayed.

  When the post-processing determining unit 212 inputs the necessity for delaying the conveyance timing and the information on the time to be delayed, the detour selection unit 213 uses the detour selection unit 213 as a conveyance path to be used for conveying the sheet of the next print job. The detour conveyance path 172 is selected and switched from the main conveyance path 171 to the detour conveyance path 172.

  When the bypass path selection unit 213 selects the bypass path 172 as the transport path used for transporting the paper for the next print job, it instructs the gate controller 214 to switch from the main transport path 171 to the bypass path 172. .

  Such a detour selection unit 213 is configured by the central processing unit 201 of the machine control board 202 shown in FIG.

  The gate control unit 214 controls switching of the first to third gates 173a to 183c in the relay conveyance device 170, and the detour selection unit 213 uses a conveyance path for conveying the sheet of the next print job. When the detour conveyance path 172 is selected, the trailing edge of the last sheet of the previous print job conveyed on the main conveyance path 171 is switched to the timing immediately after passing the first gate 173a. The gate control unit 214 is configured by the central processing unit 201 of the machine control board 202 shown in FIG.

  By passing the sheet through the detour conveyance path 172 having a long conveyance path length, the time until the sheet of the next print job arrives at the post-processing device 150 is longer than when the sheet is conveyed on the short main conveyance path 171. It becomes like this. As a result, if the paper arrival delay in the detour conveyance path 172 is longer than the post-processing time, the image forming apparatus 100 continues the printing operation without delaying the paper conveyance timing of the next print job. Can be done. In addition, even when the arrival time of the paper on the detour conveyance path 172 is shorter than the post-processing time, the time for delaying the conveyance timing can be shortened, so that the period during which the image forming apparatus 100 stops the printing operation. Can be made as short as possible.

  By the way, although the post-processing time varies depending on the content of processing, a long detour conveyance path that delays the arrival of paper to the post-processing device 150 more than necessary also causes a decrease in productivity.

  Therefore, here, as the detour conveyance path 172, first to third detour conveyance paths 172a to 172c having different lengths are provided, and the detour selection unit 213 is information on the time to be delayed, in other words, The detour conveyance path 172 having a length corresponding to the processing time is selected. Under the control of the gate control unit 214 described above, the sheet of the next print job is guided to the selected detour conveyance path 172 among the first to third detour conveyance paths 172a to 172c.

  In the case of the post-processing device 150 provided in the image forming system, the maximum post-processing time is about 2 seconds. That is, after the last sheet of the print job to be stapled is conveyed to the post-processing apparatus, the last sheet is aligned, stapled at two locations, and discharged onto the discharge tray 151. Is the time. With one place of stapling, the post-processing time is shorter, about 1 second.

  In the relay conveyance device 170 of FIG. 5, the third detour conveyance path 172c having the longest conveyance path length is a detour conveyance path corresponding to such two stapling. If the process speed is 540 mm / sec, the sheet is conveyed at a minimum of 540 mm / sec. Therefore, in order to increase the post-processing time of 2 seconds, it is necessary to extend the sheet conveyance path by 1080 mm or more. The transfer path length of the detour transfer path 172c is set to 1200 mm.

  The second detour conveyance path 172b having the second longest conveyance path length is a detour conveyance path corresponding to one place of stapling. When the process speed is 540 mm / sec, it is necessary to extend the paper conveyance path by 540 mm or more in order to earn a post-processing time of 1 second. Here, the conveyance path length of the second detour conveyance path 172b is set to 600 mm. Has been.

  The first detour conveyance path 172a having the shortest conveyance path length has a conveyance path length corresponding to a post-processing time such as a sort process for different paper discharge positions, which has a shorter post-processing time than one place of stapling. It is a detour conveyance path. Here, the conveyance path length of the first detour conveyance path 172a is set to 300 mm, and when the process speed is 540 mm / second, a post-processing time of 0.55 seconds can be gained.

  Thus, it becomes possible to select the detour conveyance path 172 having a conveyance path length corresponding to the post-processing time, and the productivity can be improved more efficiently.

  Also, there are cases where print jobs that require post-processing may be continuous. In such a case, the detour selection unit 213 further performs the next print job in a state where the detour conveyance path 172 is already used. If there is a detour conveyance path 172 that is longer than the detour conveyance path in use, this longer detour is used as a conveyance path for conveying the paper for the next print job. It is good also as a structure which selects the conveyance path 172. FIG.

  Further, in the present image forming system, when it is necessary to delay the sheet transport timing of the next print job in order to secure the post-processing time of the previous print job, the image forming apparatus 100 and the post-processing apparatus 150 are used. , And the sheet conveying mechanism of each of the relay conveying devices 170, and at least the sheet conveying speed in the relay conveying device 170 and the post-processing device 150 is set higher than the normal specified speed, thereby conveying timing in the image forming apparatus 100. The first inter-paper enlargement means 228 is provided to forcibly increase the distance between the last paper of the previous print job and the first paper of the next print job.

  Here, the first inter-paper enlargement unit 228 can also increase the conveyance speed of the paper in the path after the fixing unit 27 in the image forming apparatus 100 together with the specified speed. According to this, it is possible to further widen the gap between the sheets by increasing the sheet conveyance speed.

  The first inter-paper enlarging means 228 does not increase only the transport speed of the last paper of the previous print job, but increases the last paper of the previous print job and the first paper of the next print job. In the meantime, the sheet conveyance speed is increased to widen the sheet so that a sheet having a width capable of switching the conveyance path is formed. In the present embodiment, a configuration in which the conveyance speed of a single sheet is increased is illustrated, but a configuration in which the conveyance speed of a plurality of sheets is increased and the space between the sheets is widened may be employed.

  According to this, the spread sheet between the last sheet of the previous print job and the first sheet of the next print job created by the first sheet enlargement unit 228 is also the previous sheet. Since it can be used for the post-processing of the print job, the post-processing time that can be secured without delaying the transport timing is longer than the configuration in which the post-processing time is secured only by the bypass transport path 172.

  As a result, it is possible to shorten the length of the detour conveyance path necessary for continuing printing without delaying the conveyance timing.

  Such a first inter-sheet enlargement means 228 is used alone in the central processing unit 201 of the machine control board 202 shown in FIG. 3 or in the central processing unit 150a of the central processing unit 201 and the post-processing unit 150. Composed.

  Next, the timing for returning from the detour conveyance path 172 to the original main conveyance path 171 will be described. The simplest timing for returning is to set the timing at which the continuous print job ends and the image forming apparatus 100 enters the standby mode.

  However, in that case, many print jobs are transported through the detour transport path 172, and the possibility of jamming increases. This is because the detour conveyance path 172 is curved to ensure a long conveyance path length in a limited space, and the sheet is also conveyed in a curved state. Therefore, it can be said that the longer the conveying path length is, the more likely the jam is to occur, and the jam occurrence rate is inevitably higher than the linearly extending main conveying path 171.

  Therefore, in this image forming system, the two return means 223 that enable the used transport path to be returned from the detour transport path 172 to the main transport path 171 without the image forming system shifting to the standby state. 224. In the present image forming system, one of these two return means 223 and 224 can be selectively set by mode setting or the like, but only one of the return means may be provided.

  The first return means 223 switches the conveyance path to the shorter detour conveyance path 172 or the main conveyance path 171 between the sheets spreading due to the delay of the sheet discharge timing from the image forming apparatus 100. The first return means 223 includes a discharge timing delay detection unit 220 and a return path selection unit 221.

  The discharge timing delay detection unit 220 detects a delay in paper discharge timing from the conveyance timing in the image forming apparatus 100. For example, even if a print job is processed continuously, the distance (between sheets) between the last sheet of the previous print job and the first sheet of the next print job is included in one print job. It becomes wider than the distance between the sheets to be continuously processed. This is because the processing content instructed for the next print job is read on the image forming apparatus side, the paper size is selected, and sometimes image quality adjustment, density adjustment, and the like are performed. Further, even if a jam occurs in the image forming apparatus 100 or a sheet runs out, the space between the sheets is widened.

  When the discharge timing delay detection unit 220 detects the discharge timing delay, the discharge timing delay detection unit 220 notifies the return path selection unit 221 together with information on the delay time.

  When the detour conveyance path 172 is used for conveying the sheet and the delay of the conveyance timing is detected, the return path selection unit 221 conveys the sheet between the sheets spread due to the delay of the discharge timing. Is switched to the shorter detour conveyance path 172 or the main conveyance path 171 and returned.

  The return path selection unit 221 compares the information on the delay time with the time required for switching the transport path. If the delay time is long, the return path selection unit 221 selects the main transport path 171 all at once. In the case of being short, the shorter detour conveyance path 172 is selected, and the main conveyance path 171 is finally selected through the steps. Then, the return path selection unit 221 instructs the gate control unit 214 to switch from the detour conveyance path 172 currently used to the selected conveyance path.

  Such first return means 223 is configured by the central processing unit 201 of the machine control board 202 shown in FIG.

  When the return path selection unit 221 selects a conveyance path to be switched between sheets widened due to the discharge timing delay, the gate control unit 214 determines that the trailing edge of the last sheet of the previous print job is The timing is switched to immediately after passing through the gate 173 to be switched.

  That is, for example, if the last sheet is being conveyed through the third detour conveyance path 172c, the timing immediately after the sheet has passed through the third gate 173c. If the last sheet is being conveyed through the second detour conveyance path 172c, the timing is immediately after the sheet has passed through the second gate 173b. Similarly, if the last sheet is being conveyed through the first detour conveyance path 172b, the timing immediately after the sheet has passed through the first gate 173a.

  On the other hand, the second return means 224 raises the sheet conveyance speed at least in the relay conveyance apparatus 170 and the post-processing apparatus 150 above the specified speed, and then the sheet conveyed through the relay conveyance apparatus 170 and then to the relay conveyance apparatus 170. The distance (between the sheets) to be carried in is increased, and the conveying path is switched to the shorter detour conveying path 172 or the main conveying path 171 between the spread sheets.

  The second return unit 224 includes a second inter-sheet enlargement unit 227 and the return path selection unit 221.

  In a state where the detour conveyance path 172 is used, the second sheet-to-sheet enlargement unit 227 controls at least the sheet conveyance mechanism of the image forming apparatus 100, the post-processing apparatus 150, and the relay conveyance apparatus 170 to at least the relay conveyance. The sheet conveyance speed in the apparatus 170 and the post-processing apparatus 150 is increased from the normal specified speed, and the conveyance timing in the image forming apparatus 100 is maintained, and the sheet conveyed through the relay conveyance apparatus 170 and the next relay conveyance apparatus. This increases the distance (between sheets) to the sheet carried into 170.

  Here, the second inter-paper enlargement unit 227 can also increase the conveyance speed of the paper in the path after the fixing unit 27 in the image forming apparatus 100 together with the specified speed. According to this, it is possible to further widen the gap between the sheets by increasing the sheet conveyance speed.

  In the first inter-paper enlarging unit 228, a configuration in which the paper sheet is widened by increasing the conveyance speed of one sheet is illustrated. However, in the second inter-paper expansion unit 227, the conveyance speed of a plurality of sheets is increased. The configuration is such that the space between sheets is widened.

  Then, the return path selection unit 221 selects the shorter detour conveyance path 172 or the main conveyance path 171, and switches to the selected conveyance path between the wide sheets created by the second sheet enlargement unit 227. Instruct the gate control unit 214 as follows.

  In the case of such second return means 224, the timing for switching the conveyance path by actively increasing the distance between the sheet conveyed in the relay conveyance device 170 and the sheet next carried into the relay conveyance device 170 is positively created. Therefore, it is possible to return to the main transport path 171 more quickly than the first return means 223, and it is possible to more effectively reduce the jam problem caused by using the detour transport path 172. .

  Such a second sheet enlargement means 227 is used alone in the central processing unit 201 of the machine control board 202 shown in FIG. 3 or in the central processing unit 150a of the central processing unit 201 and the post-processing unit 150. Composed.

  Next, the processing procedure of the detour selection unit 210 will be described with reference to FIG. FIG. 6 is a flowchart of detour selection control in the relay transfer apparatus 170 performed by the detour selection unit 210.

  The generation of the print job is monitored, and when a new print job is generated (S1), it is determined whether or not the newly generated print job is in a state where the print job is continuously performed (S2). If another print job is being executed, or if another print job is being received and waiting for processing, it is determined YES and the process proceeds to S3. On the other hand, if it is determined that the print job is not continuously performed, the flow ends.

  In S3, it is determined whether or not post-processing is designated for a print job to be processed before the print job whose occurrence has been confirmed in S1 (some jobs are being processed and some are waiting to be processed). If it is determined that post-processing is not designated, the flow is terminated.

  On the other hand, when post-processing is designated in S3, post-processing time is calculated (S4). When the post-processing time is calculated in S4, the detour conveyance path 172 having the conveyance path length corresponding to the post-processing time is selected (S5). Here, when the first sheet enlargement unit 228 expedites the discharge of the last sheet of the previous print job and the sheet interval is widened, the detour conveyance path of the conveyance path length taking this into account. 172 is selected.

  Then, when the sheet of the print job (the print job generated in S1) reaches the relay conveyance device 170, the sheet is transferred to the gate control unit 214 so that the sheet is conveyed on the detour conveyance path 172 selected in S5. An instruction is issued to reserve switching to the detour conveyance path 172 (S6).

  Note that if there is a case where a print job that requires post-processing has already occurred while the detour conveyance path is being used (or selected), it may be necessary to further delay paper arrival at the post-processing device 150. It is determined whether or not there is a detour conveyance path 172 that can delay the arrival of a further sheet, and if it exists, the detour conveyance path 172 is selected in S5.

  As described above, in the case of the conventional image forming system, in order to secure the time for the post-processing device 150 to perform the post-processing of the previous print job, the feeding timing of the image forming device 100 is delayed to feed and transport. The image forming apparatus 100 uses the detour conveyance path 172 of the relay conveyance device 170 to delay the arrival timing of the subsequent print job to the paper post-processing device 150, so that the image forming apparatus 100 can perform the next printing. Jobs can be continuously printed, and the productivity of the image forming system can be increased without wasting the capability of the image forming apparatus that has been accelerated.

  Next, the processing procedure of the first return means 223 will be described with reference to FIG. FIG. 7 is a flowchart of return path selection control in the relay transfer apparatus 170 performed by the first return means 223.

  Next, it is determined whether or not there is a print to be processed (S11). If there is no print, the conveyance path is returned when the print job ends and the image forming apparatus 100 enters the standby mode. Since there is no need to implement and return immediately, the flow ends.

  On the other hand, when there is the next printing, the process proceeds to S12, and it is determined whether or not a delay occurs in the discharge timing of the sheet from the image forming apparatus 100. The delay of the paper discharge timing mentioned here means that the discharge of the next paper is later than the discharge timing of each paper that is included in the same print job and sequentially discharged. Therefore, the process of S12 is to detect a situation (state) in which the space between sheets is wider than usual.

  As described above, between the print jobs, the processing content specified in the next print job is read by the image forming apparatus, and the paper size is selected, sometimes image quality adjustment, density adjustment, etc. The space between the sheets becomes wider. Further, even when a jam or out of paper occurs, the space between the sheets is naturally widened. If such a situation is detected, YES is determined in S12 and the process proceeds to S13. On the other hand, if NO is determined in S12, the flow ends.

  In S13, it is determined whether or not the conveyance path being used is the main conveyance path 171. If the conveyance path is the main conveyance path 171, there is no need to return the conveyance path, and thus the flow ends.

  On the other hand, if it is not the main transport path 171, a transport path shorter than the detour transport path 172 in use is selected (S14). For example, if the third detour conveyance path 172c having the longest conveyance path length is in use, the second detour conveyance path 172b, the first detour conveyance path 172a, or the main conveyance path 171 shorter than that is selected. . Which one to select when there are a plurality of shorter conveyance paths is determined by how much the discharge of the sheet from the image forming apparatus 100 is delayed.

  The bypass conveyance path 172 or main conveyance path selected in S14 immediately after the trailing edge of the previous sheet formed between the wide sheets due to the discharge delay passes through the gate 173 in the relay conveyance device 170. The gate controller 214 is instructed to switch to 171 and reserves switching to the detour conveyance path 172 or the main conveyance path 171 (S15).

  As a result, for each sheet included in the same print job, such as when it takes time to print on the next sheet due to a jam or out of paper in the image forming apparatus 100, or between print jobs. If there is a time until printing on the next sheet, compared to continuous printing, the conveyance path can be switched to a shorter one by using this. Therefore, the jam problem caused by using the detour conveyance path 172 can be reduced without reducing the productivity of the image forming apparatus 100.

  Here, with reference to FIG. 8, the process of returning the used conveyance path to a shorter one in S14 of the flowchart of FIG. 7 will be described in detail.

  Normally, the registration roller 42 controls the sheet conveyance timing at a predetermined time interval N so that the sheet is continuously conveyed while holding a predetermined sheet interval. Therefore, if the time required for switching from the detour conveyance path 172 where the sheet is conveyed to the detour conveyance path 172 or the main conveyance path 171 having a shorter conveyance path length is α, the sheet conveyance timing The return conveyance path may be selected by determining whether there is a conveyance timing delay (= delay timing delay from the image forming apparatus 100) that is slower than N + α.

  That is, if it is determined in S12 of FIG. 7 that there is a delay in the paper discharge timing from the image forming apparatus 100, the switching destination transport path may be specified based on the delay time M.

  First, in S21 to S23, it is specified which of the first to third detour conveyance paths 172a to 172c the sheet currently conveyed by the relay conveyance device 170 is conveyed.

  If the third detour conveyance path 172c is used, the delay time M of the document discharge timing of the image forming apparatus 100 is changed from the third detour conveyance path 172c to the second detour conveyance path 172b. It is determined whether or not the time X1 is longer than the time X1 for securing the sheet space necessary for switching to (S26). Here, if the time is less than or equal to time X1, it is difficult to switch the transport path, and the flow is exited.

  On the other hand, if the time is longer than the time X1, is the delay time M longer than the time X2 for securing the sheet space necessary for switching from the third detour conveyance path 172c to the first detour conveyance path 171a? It is further determined whether or not (S27). Here, when the time is less than or equal to time X2, the second detour conveyance path 172b is selected (S29), and the flow is exited.

  On the other hand, when the time is longer than the time X2, it is further determined whether or not the delay time M is longer than the time X3 for securing a space between sheets necessary for switching from the third detour conveyance path 172c to the main conveyance path 171. Judgment is made (S28). Here, when the time is X3 or less, the first detour conveyance path 172a is selected (S30), and the flow is exited. When the time is longer than the time X3, the main transport path 171 is selected (S25), and the flow is exited.

  Similarly, if the second detour conveyance path 172b is being used, the delay time M of the document discharge timing of the image forming apparatus 100 is changed from the second detour conveyance path 172b to the first detour conveyance path. It is determined whether or not it is longer than the time Y1 for securing the space between sheets necessary for switching to 172a (S31). Here, when the time is Y1 or less, it is difficult to switch the conveyance path, and the flow is exited.

  On the other hand, if the time is longer than the time Y1, it is further determined whether or not the delay time M is longer than the time Y2 for securing the sheet space necessary for switching from the second detour conveyance path 172b to the main conveyance path 171. (S32). Here, when the time is Y2 or less, the first detour conveyance path 172a is selected (S33), and the flow is exited. Here, if it is larger than the time Y2, the main transport path 171 is selected (S25), and the flow is exited.

  If the first bypass conveyance path 172a is used, the image forming apparatus 100 switches the delay time M of the document discharge timing from the first bypass conveyance path 172a to the main conveyance path 171. In step S24, it is determined whether or not the time Z is longer than the time Z required to secure the space between sheets. Here, when the time is less than or equal to time Z, it is difficult to switch the conveyance path, and the flow is exited. When the time is longer than the time Z, the main transport path 171 is selected (S25), and the flow is exited.

  As an explanation of the first return means 223, in this embodiment, the image forming apparatus 100 compares the delay time M of the document discharge timing with the time α required for switching the conveyance path, and switches within the delay time M. Only when it is obtained, switching is performed, and the conveyance timing is always N + M.

  However, even if the time α required for switching the transport path exceeds the delay time M, the delay time M is included in the transport path switching time, so that the printing of the image forming apparatus 100 can be performed for returning the transport path. The time for stopping the operation can be shortened as much as possible. In other words, by adding an amount that is further insufficient to N + M, the conveyance path can be switched even if the delay time M is shorter than the time required for switching the conveyance path.

  FIG. 9 shows a processing flow in which the delay time M is extended to secure the time required for switching the transport path and the transport path to be used is returned to a shorter one.

  Here, in S41 to S43, it is specified which of the first to third detour conveyance paths 172a to 172c is currently conveyed by the sheet conveyed by the relay conveyance device 170.

  If the third detour conveyance path 172c is used, the delay time M of the document discharge timing of the image forming apparatus 100 is changed from the third detour conveyance path 172c to the second detour conveyance path 172b. It is determined whether or not it is longer than the time X1 for securing the space between sheets necessary for switching to (S47). Here, when the time is less than or equal to time X1, the conveyance timing is set to N + X1 (S50), and the flow is exited. Thereby, switching from the 3rd detour conveyance path 172c to the 2nd detour conveyance path 172b is attained.

  On the other hand, if the time is longer than the time X1, is the delay time M longer than the time X2 for securing the sheet space necessary for switching from the third detour conveyance path 172c to the first detour conveyance path 171a? Further determination is made (S48). Here, when the time is less than or equal to time X2, the conveyance timing is set to N + X2 (S51), and the flow is exited. Thereby, switching from the 3rd detour conveyance path 172c to the 1st detour conveyance path 172a is attained.

  On the other hand, when the time is longer than the time X2, it is further determined whether or not the delay time M is longer than the time X3 for securing a space between sheets necessary for switching from the third detour conveyance path 172c to the main conveyance path 171. Judgment is made (S49).

  If the time is less than or equal to time X3, the transport timing is set to N + X3 (S52), and the flow is exited. Thereby, the switching from the third detour conveyance path 172c to the main conveyance path 171 becomes possible. On the other hand, if it is larger than the time X3, the conveyance timing is set to N + M as it is (S45), and the flow is exited. Also in this case, the third detour conveyance path 172c is switched to the main conveyance path 171.

  Similarly, if the second detour conveyance path 172b is being used, the delay time M of the document discharge timing of the image forming apparatus 100 is changed from the second detour conveyance path 172b to the first detour conveyance path. It is determined whether or not the time Y1 is longer than the time Y1 for securing the sheet space necessary for switching to 172a (S53). Here, when the time is less than Y1, the transport timing is set to N + Y1 (S55), and the flow is exited. Thereby, switching from the 2nd detour conveyance path 172b to the 1st detour conveyance path 172a is attained.

  On the other hand, if the time is longer than the time Y1, it is further determined whether or not the delay time M is longer than the time Y2 for securing the sheet space necessary for switching from the second detour conveyance path 172b to the main conveyance path 171. (S54). Here, if the time is less than Y2, the conveyance timing is set to N + Y2 (S56), and the flow is exited. Thereby, switching from the second detour conveyance path 172b to the main conveyance path 171 becomes possible. On the other hand, if the time is larger than the time Y2, the transport timing is left as N + M (S45), and the flow is exited. Also in this case, the second detour conveyance path 172b is switched to the main conveyance path 171.

  If the first bypass conveyance path 172a is used, the image forming apparatus 100 switches the delay time M of the document discharge timing from the first bypass conveyance path 172a to the main conveyance path 171. In step S44, it is determined whether or not the time Z is longer than the time Z required to secure the space between sheets. Here, if it is less than the time Z, the conveyance timing is set to N + Z (S46) and the flow is exited. Thereby, switching from the first detour conveyance path 172b to the main conveyance path 171 becomes possible. On the other hand, if it is larger than the time Z, the transport timing is set to N + M as it is (S45), and the flow is exited. Also in this case, the first detour conveyance path 172b is switched to the main conveyance path 171.

  Next, the processing procedure of the second return means 223 will be described with reference to FIG. FIG. 10 is a flowchart of return path selection control in the relay transfer apparatus 170 performed by the second return means 224.

  Next, it is determined whether or not there is a print to be processed (S61). If there is no print, the conveyance path is returned when the print job ends and the image forming apparatus 100 enters the standby mode. Since it is not necessary to carry out and return immediately, the said flow is complete | finished.

  On the other hand, if there is the next printing, the process proceeds to S62, where it is determined whether or not the used conveyance path is the main conveyance path 171. Again, if the transport path in use is the main transport path 171, there is no need to return the transport path, so the flow is terminated.

  On the other hand, when the used conveyance path is not the main conveyance path 171, a conveyance path shorter than the detour conveyance path 172 in use is selected in consideration of the expansion between sheets by the second sheet-to-paper enlargement unit 227. (S63). For example, if the third detour conveyance path 172c having the longest conveyance path length is in use, the second detour conveyance path 172b, the first detour conveyance path 172a, or the main conveyance path 171 shorter than that is selected. . When there are a plurality of shorter conveyance paths, which one to select is determined in consideration of the size of the paper to be enlarged by the second paper-to-paper enlargement unit 227.

  Then, the rear end of the previous sheet (the sheet conveyed at an increased speed) that forms a wide sheet formed by increasing the conveyance speed of the sheet conveyed in front is a gate in the relay conveyance device 170. Immediately after passing through 173, the gate control unit 214 is instructed to switch to the bypass transport path 172 or the main transport path 171 selected in S63, and the switch to the bypass transport path 172 or the main transport path 171 is reserved. (S64).

  As a result, even when the timing is not between print jobs, the switching time is positively secured by increasing the paper conveyance speed between a plurality of sheets included in the same print job, so that the time is shorter. You can switch to the transport path. Therefore, the jam problem caused by using the detour conveyance path 172 can be reduced without further reducing the productivity of the image forming apparatus 100.

  Here, the first return means 223 and the second return means 224 are described separately. However, the first return means 223 and the second return means 224 may be combined. That is, a delay in the discharge timing from the image forming apparatus is detected to switch the transport path to a shorter time, and the sheet transport speed is increased to positively secure and switch the transport path. According to this, the conveyance path used more efficiently can be returned to the main conveyance path 171.

  Subsequently, referring to FIG. 11, the first paper enlarging means 228 increases the paper conveyance speed to create a wide space, and the conveyance path used in the relay conveyance device 170 is changed to a conveyance path having a longer conveyance path length. A gate switching process for switching from the main conveyance path 171 to the detour conveyance path 172 or from the short detour conveyance path 172 to the longer detour conveyance path 172 will be described.

  First, in S71, it is monitored whether or not the previous sheet for which the gate switching is reserved has been discharged from the image forming apparatus 100. When the previous sheet is discharged, each of the relay conveyance devices 170 is checked. The speed of each transport roller in the transport rollers 176a to 176g and the post-processing device 150 is increased to increase the paper transport speed (S72). As a result, the sheet one sheet prior to the sheet for which switching is reserved is transported at an increased speed after the relay transport device 170, and a wider sheet than usual is formed between the sheet for which subsequent switching is reserved. Is done.

  In this way, when the speed of each transport roller is increased in S72, the process on the transport roller side in S73 to S76 and the process on the gate side in S77 to S79 are performed in parallel thereafter. .

  First, processing on the conveyance roller side will be described. Each transport roller can detect whether or not a sheet has passed, and each transport roller monitors whether or not the previous sheet has passed (S73). When the passage of the previous sheet is detected in S73, the speed of the corresponding transport roller is returned to the normal speed (S74). The processes in S73 and S74 are performed until it is detected in S75 that the previous sheet is discharged to the post-processing device 150. In S75, when the discharge of the previous sheet to the post-processing device 150 is detected, the speeds of all the increased transport rollers are returned to the normal specified speed (S76), and the flow ends. .

  Subsequently, processing on the gate side will be described. Each of the gates 173a to 173c can detect whether or not a sheet has passed, and monitors whether or not the previous sheet has passed through the gate 173 that needs to be switched (S77). When the passage of the previous sheet is detected in S77, the corresponding gate 173 is switched (S78). The processes in S77 and S78 are performed until it is determined in S79 that all the gates 173 to be switched have been switched.

  Here, when the first detour conveyance path 172a is selected as the switching destination, the first gate 173a becomes a gate that needs to be switched. When the second detour conveyance path 172b is selected as the switching destination, the first gate 173a and the second gate 173b are gates that need to be switched. When the third detour conveyance path 172b is selected as the switching destination, the first gate 173a, the second gate 173b, and the third gate 173c are gates that need to be switched.

  If it is determined in S79 that the switching of all the gates 173 to be switched has been completed, the flow ends.

  Next, referring to FIG. 12, the second paper enlargement unit 227 increases the conveyance speed of a plurality of sheets to create a wide sheet, and further conveys the detour conveyance path 172 used in the relay conveyance device 170. Processing for switching to a short conveyance path (from the detour conveyance path 172 to the main conveyance path 171 or from the long conveyance path detour conveyance path 172 to the shorter detour conveyance path 172) will be described.

  First, in step S <b> 81, it is determined whether or not a sheet for which gate switching is reserved is not discharged from the image forming apparatus 100 before completing the process of returning the conveyance path. Here, when the sheet reserved for switching is discharged, it is not possible to secure enough space between the sheets so that the conveyance path can be switched. Therefore, it is determined that the conveyance path cannot be returned, and the flow ends.

  On the other hand, if it is determined that the sheet reserved for the next switching is not discharged, the end of the post-processing is monitored (S82), and if it is detected that the post-processing is completed, each transport roller of the relay transport device 170 is detected. 176a to 176g and the speed of each transport roller in the post-processing device 150 are increased to increase the paper transport speed (S83). As a result, a predetermined number of sheets discharged from the image forming apparatus 100 and carried into the relay conveyance apparatus 170 are conveyed at an increased speed, and the space between the sheets gradually increases. Here, the number of sheets to be conveyed at an increased speed is determined according to the time required for returning the conveyance path (switching the gate).

  When the speed of each transport roller is increased in S83, the process on the transport roller side in S84 to S87 and the process on the gate side in S887 to S90 are performed in parallel.

  First, processing on the conveyance roller side will be described. Each transport roller can detect whether or not a sheet has passed, and each transport roller monitors whether or not the last sheet to be transported at an increased speed is passed (S84). When the passage of the last sheet is detected in S84, the speed of the corresponding transport roller is returned to the normal speed (S85). The processes in S84 and S85 are performed until it is detected in subsequent S86 that the last sheet has been discharged to the post-processing device 150. When the discharge of the last sheet to the post-processing device 150 is detected in S86, the speeds of all the transport rollers that have been accelerated are returned to the normal specified speed (S87), and the flow ends.

  Subsequently, processing on the gate side will be described. Each of the gates 173a to 173c can detect whether or not a sheet has passed, and monitors whether or not the last sheet has passed through the gate 173 that needs to be switched (S88). When the passage of the last sheet is detected in S88, the corresponding gate 173 is switched (S89). The processes in S88 and S89 are performed until it is determined in S90 that the switching of all the gates 173 to be switched is completed. If it is determined in S90 that the switching of all the gates 173 to be switched has been completed, the flow ends.

  Finally, each block of the image forming system, in particular, the bypass selection unit 210, the first return unit 223, the second return unit 224, the first inter-sheet enlargement unit 228, and the gate control unit 214 are configured by hardware logic. Alternatively, it may be realized by software using a CPU as follows.

  That is, the image forming system 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, a RAM (random access memory) that expands the program, A storage device (recording medium) such as a memory for storing the program and various data is provided. An object of the present invention is to provide a recording medium in which a program code (execution format program, intermediate code program, source program) of a control program for an image forming system, which is software that realizes 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 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 a tape system such as a magnetic tape and a cassette tape, a magnetic disk such as a floppy (registered trademark) disk / hard disk, and an optical disk such as a 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 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 examples), and various modifications can be made within the scope of the claims. In other words, embodiments obtained by combining technical parts appropriately changed within the scope of the claims are also included in the technical scope of the present invention.

FIG. 3 is a block diagram illustrating functional blocks of a main part in the image forming system according to the embodiment of the present invention. FIG. 2 is a schematic diagram illustrating an overall configuration of the image forming system. FIG. 2 is an overall block configuration diagram of various unit units, an image processing unit, and the like that constitute the image forming system. FIG. 2 is an enlarged view illustrating a configuration of a main part of a reverse conveyance path of an image forming apparatus mounted on the image forming system. FIG. 2 is a schematic diagram of an apparatus in which a single unit mounted on the image forming system is formed, and a post-processing apparatus and a relay conveyance apparatus are unitized into one unit. 4 is a flowchart illustrating a procedure of detour selection control by a first return unit in the image forming system. 3 is a flowchart illustrating a procedure of return path selection control in the image forming system. It is a flowchart which shows the detailed procedure of S14 in the flowchart of FIG. It is another flowchart which shows the detailed procedure of S14 in the flowchart of FIG. 4 is a flowchart illustrating a procedure of return path selection control by a second return unit in the image forming system. 5 is a flowchart illustrating a procedure for enlarging a sheet interval and switching to a conveyance path having a long conveyance path length by a first sheet interval enlargement unit in the image forming system. 7 is a flowchart illustrating a procedure in which a second return unit in the image forming system returns to a transport path having a short transport path length by enlarging the space between sheets.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 103 Printing part 150 Post-processing apparatus 170 Relay conveyance apparatus 210 Alternate route selection means 223 1st return means 224 2nd return means 228 1st sheet expansion means 214 Gate control part

Claims (12)

An image forming apparatus that fixes an image printed on a sheet by a printing unit onto the sheet by a fixing unit, and a post-processing device that performs post-processing on the sheet discharged from the image forming apparatus. In an image forming system that controls the paper transport timing of the next print job to ensure the post-processing time of a job,
Between the image forming apparatus and the post-processing apparatus, as a transport path for transporting the paper discharged from the image forming apparatus to the post-processing apparatus, a switchable main transport path and the main transport path Is also provided with a relay conveyance device with a detour conveyance path having a long conveyance path length,
When it is necessary to delay the paper transport timing of the next print job in order to secure the post-processing time of the previous print job, the transport path in the relay transport device to which the paper of the next print job is transported An image forming system comprising: a detour selection unit that switches the main conveyance path to the detour conveyance path.   The image forming system according to claim 1, wherein the bypass conveyance path is formed in a U shape.   The detour conveyance path includes a plurality of detour conveyance paths having different lengths, and the detour selection unit selects any one of a plurality of detour conveyance paths based on a time for delaying the conveyance timing. The image forming apparatus according to claim 1.   The detour selection unit is longer than the detour conveyance path in use when it is necessary to delay the conveyance timing of the next print job in a state where the detour conveyance path is already used for the conveyance of the sheet. 4. The image forming system according to claim 3, wherein when a detour conveyance path exists, the longer detour conveyance path is selected as a conveyance path for conveying a sheet of a next print job.   When it is necessary to delay the paper transport timing of the next print job in order to secure the post-processing time of the previous print job, at least the paper transport speed in the relay transport device and the post-processing device is the specified speed. 5. An inter-paper enlargement means for increasing the distance between the last paper of the previous print job and the first paper of the next print job. The image forming system described in 1.   2. A first return means for switching a conveyance path to a shorter detour conveyance path or a main conveyance path between sheets spread due to a delay in discharge timing of sheets from the image forming apparatus. The image forming system according to claim 1.   At least the paper transport speed in the relay transport device and the post-processing device is increased above a specified speed, and the distance between the paper transported in the relay transport device and the next paper transported into the relay transport device is increased and widened. 7. The image forming system according to claim 1, further comprising a second return unit that switches the conveyance path to a shorter detour conveyance path or a main conveyance path between the sheets being fed.   The image forming system according to claim 1, wherein the post-processing is a stapling process in which a sheet is fastened with staples. An image forming apparatus that fixes an image printed on a sheet by a printing unit onto a sheet by a fixing unit, and is provided with a post-processing device that performs post-processing on the sheet discharged from the image forming apparatus. In an image forming apparatus that configures a forming system and controls sheet conveyance timing of a next print job in order to secure a post-processing time of a previous print job,
As a transport path for transporting the paper discharged from the image forming apparatus to the post-processing apparatus between the image forming apparatus and the post-processing apparatus, a switchable main transport path and the main transport path A relay transfer device equipped with a detour transfer path with a long transfer path length can be attached,
When it is necessary to delay the paper transport timing of the next print job in order to secure the post-processing time of the previous print job, the transport path in the relay transport device to which the paper of the next print job is transported An image forming apparatus comprising: a detour selection unit that switches the main conveyance path to the detour conveyance path.   The image is arranged between an image forming apparatus that fixes an image printed on a sheet by a printing unit on the sheet by a fixing unit, and a post-processing apparatus that performs post-processing on the sheet discharged from the image forming apparatus. A conveyance path for conveying the paper discharged from the forming apparatus to the post-processing apparatus includes a switchable main conveyance path and a bypass conveyance path having a conveyance path length longer than the main conveyance path. Relay transfer device.   The program for functioning a computer as each means of the image forming system of any one of Claim 1 to 8.   A computer-readable recording medium on which the program according to claim 11 is recorded.

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