Image forming system for ensuring high productivity corresponding to improved speed of continuous printing

Disclosed is an image forming system including: an image forming apparatus; finishing apparatuses; and a conveyance unit apparatus; wherein the image forming apparatus include: a control section to judge which of the finishing apparatuses performs finishing and to transmit a judgment result to the conveyance unit apparatus, and the conveyance unit apparatus includes: placement sections, a conveyance path, discharging sections, discharging-section switching sections among which a discharging-section switching section corresponding to a discharging section discharging the sheet is switched, and a control section which judges the discharging section as discharging the sheet based on the judgment result and which switches the discharging-section switching section so that the sheet is discharged to the judged discharging section.

BACKGROUND

1. Field of the Invention

The present invention relates to an image forming system.

2. Description of Related Art

Recently, a speed of continuous printing of an image forming apparatus has been improved. With this speed improvement, speeds of various finishings such as staple processing and binding processing in a finishing apparatus also need to be improved. In order to perform finishings corresponding to the speed of continuous printing of the image forming apparatus, a user needs to connect a highly-functional finishing apparatus thereto. For example, when a user uses an image forming apparatus whose speed of continuous printing is 40 ppm and then newly buys an image forming apparatus whose speed of continuous printing is 120 ppm, unless the user connects a finishing apparatus having a finishing speed corresponding to the speed of continuous printing of the new image forming apparatus thereto, finishing cannot keep up with the speed of continuous printing and productivity cannot be improved. For ensuring high productivity, an image forming system in which a plurality of finishing apparatuses are connected to one image forming apparatus in series has been invented.

Cited document 1 (Japanese Patent Application Laid-open Publication No. 2003-312934) discloses a finishing apparatus in which each function to execute finishing is modularized and respective modules are detachably/attachably connected to one finishing apparatus in parallel with one another, and which includes a sheet distributing member to switch a sheet conveyance path for a given module depending on user's intended use.

Cited document 2 (Japanese Patent Application Laid-open Publication No. 2004-205772) discloses an image forming system which makes finishings more efficient by connecting two finishing apparatuses so that they perform finishings alternately.

SUMMARY

However, though the finishing apparatus described in cited document 1 can perform finishing based on the module selected by the sheet distributing member to a sheet conveyed from the image forming apparatus, the finishing apparatus cannot perform finishing corresponding to the speed of continuous printing of the image forming apparatus when a processing speed of the connected finishing apparatuses are lower than the speed of continuous printing of the image forming apparatus. As a result, productivity cannot be improved. In addition, when a serious failure bringing a service call occurs in any of the finishing apparatuses, the whole of the image forming apparatus cannot be used, and this may increase a downtime. The same can be said for the image forming system described in cited document 2. Although the image forming system can make two finishing apparatuses perform finishings alternately, high productivity corresponding to the improved speed of continuous printing of the image forming apparatus cannot be ensured.

According to the first aspect of the present invention, there is provided an image forming system including:

an image forming apparatus to form an image on a sheet;

a plurality of finishing apparatuses each of which perform finishing to the sheet image-formed by the image forming apparatus to discharge the sheet; and

a conveyance unit apparatus to which each of the image forming apparatus and the respective finishing apparatuses is connected; wherein

the image forming apparatus includes:a control section to judge which of the finishing apparatuses performs the finishing to the sheet on the basis of a previously-determined method to transmit a judgment result to the conveyance unit apparatus when a number of sets to be output according to a job to be executed is plural and when a plurality of the finishing apparatuses each of which can perform finishing corresponding to the job are connected to the conveyance unit apparatus, and

the conveyance unit apparatus includes:a plurality of placement sections in which the plurality of finishing apparatuses can be placed respectively,a conveyance path along which the sheet image-formed by the image forming apparatus is conveyed,a plurality of discharging sections provided in the placement sections respectively, which discharging sections discharge the sheet conveyed along the conveyance path to the finishing apparatuses respectively placed in the placement sections,one or more discharging-section switching sections among which a discharging-section switching section corresponding to a discharging section discharging the sheet conveyed along the conveyance path among the plurality of discharging sections is switched, anda control section to judge the discharging section which discharges the sheet on the basis of the judgment result received from the control section of the image forming apparatus to switch the discharging-section switching section so that the sheet is discharged to the judged discharging section.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following, a configuration of an image forming system according to the present invention will be described with reference to the drawings.

FIG. 1is an overall view showing a whole configuration of an image forming system according to the embodiment of the present invention.

An image forming system1000includes an image forming apparatus1, a feeding unit5, a conveyance unit apparatus6, a first finishing apparatus3, and a second finishing apparatus4. Incidentally, though details will be described later, the configuration is not limited to the example shown inFIG. 1, and a plurality of finishing apparatuses of arbitrary types may be connected to the conveyance unit apparatus6.

The image forming apparatus is an apparatus to form an image/images on a sheet/sheets, and as shown inFIG. 1, configured to include an operation section12, a feeding tray13a, an image forming section15, and a conveyance section18, and so on.

The operation section12is configured to include a Liquid Crystal Display (LCD), various operation keys such as a start button for instructing to start printing, a touch panel integrally formed with the LCD, and so on. The operation section12displays various operation buttons, a state of each apparatus constituting the image forming system1000, an operation state of each function and the like on the LCD, and outputs an operation signal corresponding to depressing operation onto the operation keys or pressing operation on the touch panel by a user to an image-forming-apparatus control section100to be hereinafter described, according to a control signal input from the image-forming-apparatus control section100.

In addition, via the operation section12, a user can set various finishings (punching processing, folding processing, staple processing, shift processing, case binding processing, and so on) and a sheet size (A4, B5or the like).

The feeding tray13ahouses sheets, on which images are to be transferred (formed) respectively, by sheet size or sheet kind, similarly to the feeding unit5. The feeding tray13ais configured to feed the sheets to an image forming section15to be hereinafter described.

The image forming section15is composed of: a photosensitive drum on which an electrostatic latent image is formed; a charging device to uniformly charge the photosensitive drum; a laser unit to irradiate a surface of the uniformly-charged photosensitive drum with laser light which is turned ON/OFF depending on image data to form the electrostatic latent image; a developing device to visualize the electrostatic latent image to be a toner image; a transferring/detaching device to transfer the toner image on the surface of the photosensitive drum onto the conveyed sheet and then detach the sheet from the surface of the photosensitive drum; a cleaning device to remove toner which remains on the surface of the photosensitive drum after transferring; a fixing device to heat/pressurize the toner image on the sheet to fix the toner image, and so on. The image forming section15forms the image on the sheet on a job basis by an electrophotography system according to a control signal input from the image-forming-apparatus control section100. The sheet on which the toner has been fixed is conveyed to the conveyance unit apparatus6by the conveyance section18.

The conveyance section18is composed of a conveyance roller and a conveyance belt, and a motor to drive them, and so on. The conveyance section18conveys the sheets housed in the feeding tray13aor the feeding unit5along a conveyance path to discharge the sheets to the conveyance unit apparatus6according to the control signal input from the image-forming-apparatus control section100. The conveyance section18also includes a sensor to detect completion of sheet discharge to the conveyance unit apparatus6, and transmits a corresponding signal when sheet discharge from the image forming apparatus1is completed.

The feeding unit5houses the sheets by a size of each sheet on which the image is to be formed, similarly to the feeding tray13a. The feeding unit5feeds the sheets to the image forming section15.

FIG. 2is a front view showing a schematic configuration of the conveyance unit apparatus constituting the image forming system according to the embodiment of the present invention.

As shown inFIG. 2, the conveyance unit apparatus6is configured to include a conveyance path64, a sheet detection sensor73, a conveyance-path switching plate71, a plurality of discharging-section switching plates67, an upper-stream-side delivery section70, a down-stream-side delivery section69, a plurality of placement sections80, and so on.

The conveyance path64receives the sheets discharged from the conveyance section18of the image forming section1to convey the sheet to the down-stream-side delivery section69or the upper-stream-side delivery section70. The conveyance path64has an openable and closable door (not-shown) on the upper side thereof, and makes the door open when a sheet jam or the like occurs during sheet conveyance along the conveyance path64so that recovery operations can be performed easily.

The sheet detection sensor73outputs an ON/OFF signal when the sheet is received by the conveyance path64and passes a position where the sensor is placed. The sheet detection sensor73is configured to output the signal output from the sheet detection sensor73to a conveyance-unit-apparatus control section600to be hereinafter described. The conveyance-unit-apparatus control section600can detect that the conveyance unit apparatus6receives the sheets by receiving this output signal.

The conveyance-path switching plate71can be switched so that the sheets conveyed along the conveyance path64are conveyed to one of the down-stream-side delivery section69and the upper-stream-side delivery section70.

The discharging-section switching plates67respectively function as discharging-section switching sections and can be switched so that the sheets conveyed along the conveyance path64are discharged to one of or any of discharging sections81of placement sections80to be hereinafter described. The discharging-section switching plates67are provided in the placement sections80respectively, and one or more of the plurality of discharging-section switching plates67can be arbitrarily switched according to the control signal from the conveyance-unit-apparatus control section600.

The upper-stream-side delivery section70is provided on the upper stream side of the conveyance unit apparatus6, and discharges the sheets for which finishings are unnecessary, or the subsequent sheets when the sheet jam or the like occurs in the finishing apparatuses respectively placed in the placement sections80, among the sheets conveyed along the conveyance path64.

The down-stream-side delivery section69is provided on the down-stream-side end portion of the conveyance unit apparatus6, and discharges the sheets to be subjected to finishing by the finishing apparatuses respectively placed in the placement sections80among the sheets image-formed by the image forming apparatus1and conveyed along the conveyance path64. The down-stream-side delivery section69also functions as an alternate outlet such as a sheet discharge tray of the upper-stream-side delivery section70or the finishing apparatuses for discharging the subsequent sheets when the sheet jam or the like occurs in the upper-stream-side delivery section70or the finishing apparatuses respectively placed in the placement sections80.

The plurality of (for example, four) placement sections80are provided over an area from the upper stream side to the down stream side of the conveyance unit apparatus6, and each of the placement sections80includes the discharging section81, a bringing-in section82, a attaching/detaching section83, a connector84and a connection detecting section85. The finishing apparatuses are directly, namely without other finishing apparatus between each finishing apparatus and the conveyance unit apparatus6, placed in the conveyance unit apparatus6. The number of the placement sections80is arbitrary, and not especially limited. For example, the number of the placement sections80may be five.

The discharging section81includes a gate81awhich can be connected to an introducing port (for example, introducing port30aor40a) of the finishing apparatuses respectively placed in the placement sections80, conveyance rollers (not shown), and so on. The sheets conveyed along the conveyance path64are introduced to each of the finishing apparatuses through the gate81aand the conveyance rollers.

The bringing-in section82includes a gate82awhich can be connected to a leading-out port (for example, a leading-out port30bof the first finishing apparatus3) of the finishing apparatus including the leading-out port in each of the finishing apparatuses respectively placed in the placement sections80, conveyance rollers (not shown), and so on. The bringing-in section82brings the sheets which have been introduced to each of the finishing apparatuses by the discharging section81and to which finishing has been performed in the conveyance path64again through the gate82aand the conveyance rollers.

The attaching/detaching section83is composed of a pin joint hole83a, a solenoid83b, and so on.

The pin join hole83afits together with a mounting pin (for example, a mounting pin30for40fto be hereinafter described) of each of the finishing apparatuses respectively placed in the placement sections80, and enables each of the finishing apparatuses to be detachable and attachable. The pin join hole83aincludes a penetrating slot (not shown) through which a plunger of the solenoid83bpenetrates, the slot being formed from the upper side to the lower side of the pin join hole83a.

The solenoid83bincludes the plunger (not shown) which straightly drives up and down when current flows, and configured to penetrate both penetrating slots of the mounting pin and the pin join hole83afrom the upper part to the lower part while the mounting pin fits together with the pin join hole83a.

The connector84is a power source connector and connected to a power source connector (for example, a connector30gor connector40g) of each of the finishing apparatuses respectively placed in the placement sections80so as to supply power to the finishing apparatuses.

The connection detection sensor85detects attachment/detachment of each of the finishing apparatuses to each of the placement sections80by a noncontact detecting means such as light and magnetism, for example.

The conveyance-unit-apparatus control section600to be hereinafter described can confirm connection states of the finishing apparatuses by an output signal from each of the connection detection sensors85.

FIGS. 3A and 3Bare diagrams for explaining about a certain kind of the finishing apparatus (the first finishing apparatus3shown inFIGS. 1,3A and3B is assumed to be the finishing apparatus of “type A”) which constitutes the image forming system according to the embodiment of the present invention.FIG. 3Ais a front view, andFIG. 3Bis a rear view. In the embodiment, types of the finishing apparatuses connected to the conveyance unit apparatus6are classified according to a content of each finishing executable by the finishing apparatuses. For example, the finishing apparatuses are classified such that the finishing apparatuses which can perform side stitching are classified into type A and the finishing apparatuses which can perform case binding are classified into type B, for example. The types of the finishing apparatuses are not limited as long as they are classified according to a previously-determined rule. For example, the finishing apparatuses whose finishing contents and processing speeds are same as each other respectively can be classified into the same type. A memory (not shown) of each of the finishing apparatuses stores information indicating its type, and the image-forming-apparatus control section100and the conveyance-unit-apparatus control section600obtain this information to determine each type of each of the finishing apparatuses connected to the conveyance unit apparatus6.

The first finishing apparatus3of type A is, as shown inFIGS. 1,3A and3B, configured to include a sheet discharge tray31, the introducing port30a, the leading-out port30b, a conveyance-path switching plate30c, a staple processing section32, a stacker33, a shift processing section34, a wheel section30d, sheet-jam detection sensors37, a handle30e, the mounting pin30f, and the connector30g. The first finishing apparatus3can perform staple processing or shift processing, and side binding, as finishings to the sheet conveyed from the conveyance unit apparatus6.

The sheet discharge tray31discharges the sheet to which staple processing or shift processing has been performed.

The introducing port30ais connected to the discharging section81of the conveyance unit apparatus6, and introduces the sheets conveyed from the discharging section81to convey the sheets to the staple processing section32or the shift processing section34. The introducing port30ais provided with a sensor to detect an end of introducing the sheet, and generates a signal indicating completion of sheet discharge from the conveyance unit apparatus6to the first finishing apparatus3.

The leading-out port30bis connected to the bringing-in section82of the conveyance unit apparatus6, and makes the conveyance path64of the conveyance unit apparatus6receive the sheet to which the staple processing or shift processing has been performed by the staple processing section32or the shift processing section34.

The conveyance-path switching plate30cswitches the conveyance path so that the sheet conveyed from the staple processing section32or the shift processing section34is conveyed to one of the sheet discharge tray31and the leading-out port30b.

The staple processing section32performs staple processing to the sheet by injecting staples into two points on a marginal portion of the sheet.

The stacker33makes a plurality of sheets to which staple processing is performed by the staple processing section32to be accumulated.

The shift processing section34performs shift processing to change a position to which the sheet is discharged at every predetermined number of pages.

The wheel section30dincludes casters, in which wheels can whirl freely according to a moving direction.

The sheet-jam detection sensors37are provided at multiple portions along the sheet conveyance path, and when detecting the sheet jam in the conveyance path, outputs sheet-jam information composed of an output signal thereof to the conveyance-unit-apparatus control section600through a serial communication section301to be hereinafter described.

The handle30eis a pull handle, which is pulled when detaching the first finishing apparatus3from the conveyance unit apparatus6. Since the wheel section30dwhirls in the pulling direction, the handle30eenables conveyance of the first finishing apparatus3.

The mounting pin30ffits together with the pin join hole83aof the conveyance unit apparatus6, and enables attachment/detachment of the first finishing apparatus3and the conveyance unit apparatus6. The mounting pin30fincludes a penetrating slot (not shown) through which a plunger of the solenoid83bpenetrates, the penetrating slot being formed from the upper side to the lower side of the mounting pin30f, while the mounting pin30ffits together with the pin join hole83a.

The connector30gis a power source connector, and connected to the connector84of the conveyance unit apparatus6to receive power supply from the conveyance unit apparatus6. The first finishing apparatus3starts power supply from the conveyance, unit apparatus6via the connector30gaccording to an instruction from the conveyance-unit-apparatus control section600. When power is supplied to each section of the first finishing apparatus3and preparation of finishing is completed, a signal indicating completion of preparation is transmitted to the conveyance-unit-apparatus control section600.

FIGS. 4A and 4Bare diagrams for explaining the finishing apparatus of a certain type (assumed to be “type B”) which constitutes the image forming system according to the embodiment of the present invention.FIG. 4Ais a front view, andFIG. 4Bis a rear view.

As shown inFIGS. 1,4A and4B, the second finishing apparatus4of type B is configured to include a sheet discharge tray42, the introducing port40a, a bookbinding section41, a book accumulation section43, a moving wagon46, a front-cover-sheet housing section48a, sheet-jam detection sensors47, a wheel section40d, a handle40e, the mounting pin40f, the connector40g, and so on. The second finishing apparatus4can perform case binding as finishing to the sheets conveyed from the conveyance unit apparatus6.

The sheet discharge tray42can discharge the sheets to which finishing has been performed by the second finishing apparatus4of type B.

The introducing port40ais connected to the discharging section81of the conveyance unit apparatus6, and introduces the sheets discharged from the discharging section81. The introducing port40ais provided with a sensor to detect an end of introducing the sheets, and generates a signal indicating that sheet discharge from the conveyance unit apparatus6to the second finishing apparatus4of type B has been completed.

The bookbinding section41applies paste to a sheet bundle, and envelops the sheet bundle with the front cover sheet supplied from the front-cover-sheet housing section48ato produce booklets.

The book accumulation section43is composed of a chassis43aand door49, accumulates the booklets produced in the bookbinding section41, and displaces the accumulated booklets to the moving wagon46.

The chassis43ais a chassis portion of the book accumulation section43.

The door49is provided on the left-surface side of the chassis43aso as to be operable and closable. The door49is configured to open when the moving wagon46is attached or detached, for example.

The moving wagon46is provided so as to be detachable and attachable from/to the chassis43aof the book accumulation section43. By displacing the bookbinded and accumulated booklets to the moving wagon46, these booklets can be taken out from the second finishing apparatus4of type B to be transported.

The front-cover-sheet housing section48ahouses the front cover sheets of multiple types, and supplies a predetermined front cover sheet when the bookbinding section41perform bookbinding to produce the sheet bindles.

The wheel section40dincludes casters, in which wheels can whirl freely according to a moving direction.

The sheet-jam detection sensors47are provided at multiple portions along the sheet conveyance path, and when detecting the sheet jam, outputs sheet-jam information composed of an output signal thereof to the conveyance-unit-apparatus control section600through a serial communication section401to be hereinafter described.

The handle40eis a pull handle, since the wheel section40dwhirls in pulling direction when pulling the handle40eas detaching the first finishing apparatus of type B from the conveyance unit apparatus6, the first finishing apparatus of type B can be transported easily.

The mounting pin40ffits together with the pin join hole83aof the conveyance unit apparatus6, and enables attachment/detachment of the first finishing apparatus of type B and the conveyance unit apparatus6. The mounting pin40fincludes a penetrating slot (not shown) through which the plunger of the solenoid83bpenetrates, the penetrating slot being formed from the upper side to the lower side of the mounting pin40fwhile the mounting pin40ffits together with the pin join hole83a.

The connector40gis a power source connector, and is connected to the connector84of the conveyance unit apparatus6to receive power supply from the conveyance unit apparatus6. The first finishing apparatus of type B starts power supply from the conveyance unit apparatus6via the connector40gaccording to an instruction (for example, printing instruction) from the conveyance-unit-apparatus control section600. When power is supplied to each section of the first finishing apparatus of type B and preparation of finishing is completed, a signal indicating completion of preparation is transmitted to the conveyance-unit-apparatus control section600.

Although two types are explained above, various known finishing apparatuses may be applied as the finishing apparatuses connected to the conveyance unit apparatus6as long as they can be connected to the finishing unit apparatus6and their type are classified according to finishing contents.

Next, placement examples of the finishing apparatuses with respect to the conveyance unit apparatus6will be described.

FIGS. 5A-5Care front views showing placement examples of the finishing apparatuses with respect to the conveyance unit apparatus6according to the embodiment of the present invention. In the examples shown inFIGS. 5A-5C, the number of types of the finishing apparatuses is three (the finishing apparatus A of type A, the finishing apparatus B of type B, and the finishing apparatus C of type C).

The finishing apparatuses can be placed in the placement sections80respectively as shown inFIGS. 5A-5Cas long as each of the finishing apparatuses includes the introducing port connectable to the discharging section81and the mounting pin which can fit together with the pin join hole83aso that power is applied from the connector84. For example, as shown inFIG. 5A, the finishing apparatuses may be placed discretely so that the placement section80in which the finishing apparatus is not placed exists between the placement sections80in each of which the finishing apparatus is placed.

As shown inFIG. 5B, the finishing apparatuses (for example, two finishing apparatuses C) may be provided in a plurality of placement sections80respectively.

As shown inFIG. 5C, two finishing apparatuses of one type (for example, type C) may be provided.

As shown inFIG. 6A, a configuration where the finishing apparatus B is placed on the most-down-stream side of the conveyance unit apparatus6so that the finishing apparatus B protrudes outside of the conveyance unit apparatus6may be adopted. According to this configuration, for example, the finishing apparatus of larger size than other finishing apparatuses (for example, the finishing apparatus to perform staple processing or punching processing), for example the finishing apparatus to perform case binding, can be placed so as to be across two placement sections80.

As shown inFIG. 6B, a configuration where three finishing apparatus of one type are placed may also be adopted.

(Control Configuration of Image Forming System)

Next, a control configuration of the image forming system1000will be described with reference toFIG. 7.

FIG. 7is a block diagram of the image forming system100according to the embodiment of the present invention.

The image forming apparatus1is composed of the image-forming-apparatus control section100, a serial communication section101, a network communication section102, a feeding section103, a storage section150, the operation section12, the image forming section15, the conveyance section18, and so on. Since the operation section12, the image forming section15and the conveyance section18are as mentioned above, explanations thereof are omitted here.

The image-forming-apparatus control section100is mainly composed of a CPU and a RAM, and controls processings with respect to the whole system such as image reading, image formation, wait processing to stop image formation during a predetermined time between image forming processings for the sheets to be printed successively to avoid continuous printing, and sheet conveying, and all controls of the image forming system.

The image-forming-apparatus control section100receives output settings such as various finishings set by a user via the operation section12as operation signals from the operation section12. On the basis of the operation signals received by the image-forming-apparatus control section100, sheet information (finishing information) which is composed of kind of necessary processing, sheet size for the processing, and so on, is created per each sheet on which the image is formed to be stored in the RAM.

When starting printing based on the job data input from not-shown personal computer or the like, the image-forming-apparatus control section100transmits a signal indicating that to the conveyance-unit-apparatus control section6006through the serial communication section101. When printing and output have been completed, similarly to the above, the image-forming-apparatus control section100transmits a signal indicating completion of printing and output to the conveyance-unit-apparatus control section600through the serial communication section101.

Moreover, the image-forming-apparatus control section100judges which of the finishing apparatuses should be used for image formation, and transmits a judgment result to the conveyance unit, apparatus6. In the embodiment, this judgment result is contained in a sheet ID given to each sheet. The sheet ID is used for identifying the image-formed sheet. The sheet ID includes information for identifying the finishing apparatus to perform finishing. For example, when the sheet ID is “1a”, “1” of “1a” indicates that the sheet is the first sheet, and “a” of “1a” indicates that the finishing apparatus to be used is the first finishing apparatus3on the most upper stream. When the sheet ID is “1b”, “1” of “1b” indicates that the sheet is the first sheet, and “b” of “1b” indicates that the finishing apparatus to be used is the second finishing apparatus4on the second upper stream. Thus, every time image formation is performed on the sheet corresponding to the given sheet ID, the image-forming-apparatus control section100transmits the sheet ID to the conveyance-unit-apparatus control section600through the serial communication section101. The conveyance-unit-apparatus control section6006judges which of the finishing apparatuses should be used based on the received sheet ID, and judges which of the gates should be opened/closed. The sheet ID is not limited to the above, and may be other data format as long as it includes information for identifying the number of sheets to be printed according to the job, and the finishing apparatus to be used for the sheets. For example, the sheet ID may include a character string like “page1-1, FNS3” (indicating the first page of the first set and the third finishing apparatus is used).

The serial communication section101transmits/receives information such as control information with serial communication to/from the conveyance unit apparatus6. The serial communication section101transmits the sheet information stored in the RAM to the conveyance unit apparatus6for each sheet to be image-formed. The serial communication section101can obtain apparatus information of the first finishing apparatus3or the second finishing apparatus4transmitted from a serial communication section601of the conveyance unit apparatus6.

The network communication section102transmits/receives the job data including the printing data, the sheet information, and the number of sets to be printed to/from external equipment such as a personal computer via a Local Area Network (LAN).

The feeding section103is composed of the abovementioned feeding tray13a, feeding unit5, and so on. The feeding section103feeds the sheets of various sizes (for example, A4, B5and the like) to be image-formed from the feeding tray13aor the feeding unit5as necessary. The feeding section103is provided with a size detection sensor (not shown) to detect sheet sizes and a presence/absence detection sensor (not shown) to detect presence/absence of each size of sheet. There sensors output the detected size and presence/absence of the sheet to the image-forming-apparatus control section100.

The storage section150stores, in addition to various control programs to be executed by the image-forming-apparatus control section100, the received job data, various pieces of setting information, parameters necessary for performing processings with the program, data of processing results, and so on.

The conveyance unit apparatus6includes the conveyance-unit-apparatus control section600, the serial communication section601, a serial communication section602, a power supply section604, a storage section650, one or more of the placement sections80, the sheet detection sensor73, and so on. Since the placement sections80and the sheet detection sensor73are as above-mentioned, explanations thereof are omitted here.

The conveyance-unit-apparatus control section600is mainly composed of a CPU and a RAM, and performs all controls such as various processings in the conveyance unit apparatus6.

The RAM obtains the sheet information transmitted from the image forming apparatus1and the apparatus information transmitted from each of the finishing apparatuses to temporarily store these pieces of information. The apparatus information is information for identifying each of the finishing apparatuses respectively connected to the conveyance unit apparatus6, and includes pieces of information such as a type and processing speed of each of the finishing apparatuses. The apparatus information is obtained from each of the finishing apparatuses according to the instruction of the conveyance-unit-apparatus control section600when the finishing apparatuses each including the introducing port connectable to the discharging section81and the mounting pin which can fit together with the pin joint hole83aand each being supplied with a power source from the connector84are connected to the conveyance unit apparatus6respectively. The apparatus information is stored in not-shown memories or the like of the finishing apparatuses.

The conveyance-unit-apparatus control section600receives completion of sheet discharge from the image forming apparatus1through the serial communication section601. In the image forming apparatus1, when the discharging section18discharges the sheets, the sensor of the discharging section18transmits the signal indicating completion of sheet discharge to the conveyance-unit-apparatus control section600. The conveyance-unit-apparatus control section600detects the completion of sheet discharge by receiving this signal.

The conveyance-unit-apparatus control section600also controls switching of the discharging-section switching plates67based on the sheet information received from the image forming apparatus1. The signals indicating completion of sheet discharge are received from the first finishing apparatus3and the second finishing apparatus4through the serial communication section602.

The serial communication sections601,602transmit/receive various pieces of information such as control information and apparatus information with serial communication to/from the image forming apparatus1, the first finishing apparatus2, and the second finishing apparatus4.

The sheet information such as the sheet ID transmitted from the image forming apparatus1is obtained via the serial communication section601, and the apparatus information of the first finishing apparatus3or the second finishing apparatus4is transmitted to the image forming apparatus1. The conveyance-unit-apparatus control section600obtains the apparatus information from the first finishing apparatus3or the second finishing apparatus4through the serial communication section602.

The power supply section604supplies power to each of the finishing apparatuses respectively placed in the placement sections80when executing a power control program650bto be hereinafter described.

The storage section650stores, in addition to various control programs to be executed by the conveyance-unit-apparatus control section600, various pieces of setting information, parameters necessary for performing processing with the programs, data of processing results, and so on.

The conveyance-unit-apparatus control section600performs a control to switch the conveyance-path switching plate71and the discharging-section switching plates67based on the sheet information stored in the conveyance-unit-apparatus control section600by the program stored in the storage section650.

Specifically, when executing this program, the conveyance-unit-apparatus control section600judges to which of finishing apparatuses respectively placed in the placement sections80the sheets are discharged based on the sheet ID included in the sheet information. The discharging-section switching plates67are switched so that the sheets are discharged to the discharging section81corresponding to the judged finishing apparatus. Incidentally, a method for switching the discharging-section switching plates67is not limited to the above as long as switching is performed based on the information for indicating the finishing apparatus to be used transmitted from the image forming apparatus1. For example, the information for identifying the finishing apparatus to be used may be transmitted separately from the sheet information.

In addition, the conveyance-unit-apparatus control section600may switch the conveyance-path switching plate71so that the sheets are delivered to the upper-stream-side delivery section70when the sheet information does not include information regarding finishing of the sheets.

When the conveyance-unit-apparatus control section600judges that notification of print start has been received from the image forming apparatus1by controlling by the program stored in the storage section650, the conveyance-unit-apparatus control section600judges which of the finishing apparatuses is used in the job based on the sheet ID or the like transmitted from the image forming apparatus, supplies power the finishing apparatus which is to receive the sheets, via the power supply section604, and controls the power supply section604not to supply power to the finishing apparatus other than the above finishing apparatus.

The conveyance-unit-apparatus control section600also performs control to restrict detachment of the finishing apparatus to which power is supplied among the finishing apparatuses respectively placed in the placement sections80by controlling by the program stored in the storage section650.

Specifically, the control section600drives the solenoid83bof the attaching/detaching section83so that the finishing apparatus to which power is supplied through the power supply section604is prevented from being detached from each of the placement sections80.

The first finishing apparatus3is configured to include a first-finishing-apparatus control section300, the serial communication section301, a conveyance section303, the staple processing section32, and the shift processing section34.

Since the staple processing section32and the shift processing section34are as abovementioned, explanations thereof are omitted here.

The first-finishing-apparatus control section300is mainly composed of a CPU and a RAM, and controls finishings (staple processing, shift processing and the like) in the staple processing section32and the shift processing section34, and so on.

The serial communication section301transmits/receives information such as control information to/from the conveyance unit apparatus6with serial communication.

The serial communication section301transmits sheet-jam information output from the sheet-jam detection sensor37to the conveyance unit apparatus6, and transmits the apparatus information including information for identifying the type of each of the finishing apparatuses responding to a transmission request from the conveyance unit apparatus6.

The serial communication section301also transmits a preparation completion notification indicating that the first finishing apparatus3is in an operatable state to the conveyance unit apparatus6.

The conveyance section303controls the sheet conveyance path for the sheet received by the introducing port30a.

Specifically, the conveyance section303controls switching between the path for conveying the sheets to the sheet discharge tray31and the path for returning the sheets conveyed to the introducing port30bto the conveyance path64of the conveyance unit apparatus6, with the conveyance-path switching plate30c, for example.

The second finishing apparatus4is configured to include a second-finishing-apparatus control section400, the serial communication section401, a conveyance section403, a storage section450, the bookbinding section41n, the book accumulation section43, and so on.

Since the bookbinding section41and the book accumulation section43are as abovementioned, explanation thereof are omitted here.

The second-finishing-apparatus control section400is mainly composed of a CPU and a RAM, and controls finishings such as case binding in the second finishing apparatus and the like.

The serial communication section401functions to transmit/receive information such as control information to/from the conveyance unit apparatus6with serial communication.

The serial communication section401transmits sheet-jam information output from the sheet-jam detection sensor47to the conveyance unit apparatus6, and transmits apparatus information including information for identifying the type of each of the finishing apparatuses responding to the transmission request from the conveyance unit apparatus6.

The serial communication section401also transmits a preparation completion notification indicating that the second finishing apparatus4is in an operable state to the conveyance unit apparatus6.

The conveyance section403controls conveyance paths (for example, the path for conveying the sheets to the sheet discharge tray41) for the sheets received by the introducing port40a.

Next, operations will be described.

FIG. 8shows a flowchart of processing to be performed in the image forming apparatus1when the power source is turned on. The processing shown inFIG. 8is executed by cooperation between the image-forming-apparatus control section100and the programs stored in the storage section150.

As shown inFIG. 8, the image-forming-apparatus control section100firstly requests the conveyance unit apparatus6to send the apparatus information regarding each of the finishing apparatuses respectively placed in the placement sections80(Step S101). Next, the image-forming-apparatus control section100judges whether or not a notification of the apparatus information has been received from the conveyance unit apparatus6(Step S102).

When the image-forming-apparatus control section100does not judge that the apparatus information has been received (Step S102: NO), the processing returns to Step S102, and it is judged whether or not the notification of the apparatus information has been received from the conveyance unit apparatus6.

When the image-forming-apparatus control section100judges that the apparatus information has been received (Step S102: YES), the image-forming-apparatus control section100makes the LCD of the operation section12display the connection state of each of the finishing apparatuses respectively connected to the conveyance unit apparatus6based on the apparatus information (Step S103). A display screen of Step S103includes, though being not especially limited, information such as the type of each of the finishing apparatuses respectively connected to the conveyance unit apparatus6.

The image-forming-apparatus control section100secondly judges whether or not the printing instruction has been input from the operation section or the like (Step S104). The printing instruction is input by depressing a start button of the operation section12or receiving the job data from a now-shown external apparatus via the network. When the printing instruction is input, the image-forming-apparatus control section100transmits information indicating that to the conveyance unit apparatus6.

When the control section does not judge that the printing instruction has been input (Step S104: NO), the processing returns to Step S104, and it is judged whether or not the printing instruction has been input from the operation section12or the like.

When the control section judges that the printing instruction has been input (Step S104: YES), the image-forming-apparatus control section100judges whether or not a speed of continuous printing of the image forming apparatus1is equal to a speed of continuous processing of the finishing apparatuses connected to the conveyance unit apparatus6or less (Step S105). The information regarding the speed of continuous processing of each of the finishing apparatuses respectively connected to the conveyance unit apparatus6is contained in the apparatus information received in Step S102, and stored in the storage section150or the like.

When the image-forming-apparatus control section100does not judge that the speed of continuous printing is equal to the speed of continuous processing or less (Step S105: NO), the image-forming-apparatus control section100judges whether or not there is the plurality of (N of) finishing apparatuses of the same type among the finishing apparatuses respectively connected to the conveyance unit apparatus6on the basis of the received pieces of apparatus information of the finishing apparatuses (Step S106). For example, in the case of a connection example shown inFIG. 5A, since there are one finishing apparatus of type A, one finishing apparatus of type B, and one finishing apparatus of type C, which are connected to the conveyance unit apparatus6, the image-forming-apparatus control section100does not judge that there are the plurality of finishing apparatus of the same type in Step S106. In the case of a connection example shown inFIG. 5B, since there are one finishing apparatus of type A and two finishing apparatuses of type C, which are connected to the conveyance unit apparatus6, the image-forming-apparatus control section100judges that there are the plurality of finishing apparatus of the same type, namely two finishing apparatuses of type C, in Step S106.

When the image-forming-apparatus control section100judges that there are a plurality of finishing apparatuses of the same type (Step S106: YES), the image-forming-apparatus control section100judges whether or not the remaining number of the number X of sets to be processed is equal to N or more (Step S107). The number X of sets is contained in the job data, and stored in the storage section150.

When the image-forming-apparatus control section100judges the remaining number is equal to N or more (Step S107: YES), the image-forming-apparatus control section100determines page distributing processing (Step S108). Specifically, the image-forming-apparatus control section100determines the finishing apparatus to which the sheets discharged from the image forming apparatus1to the conveyance unit apparatus6should be distributed based on the number of sets and finishing content contained in the job data, the speed of continuous printing of the image forming apparatus, and the received apparatus information. For example, when the speed of continuous printing of the image forming apparatus1is 120 ppm and there are two finishing apparatuses of the same type each having the processing speed of 60 ppm, and when five documents are printed/processed, the page distributing processing becomes as follows depending on the number of sets.

When the number of sets is one (1), the image forming apparatus1performs image formation of the first sheet, and then performs wait processing during the time necessary for one sheet, namely for 0.5 seconds. After performing image formation of the second sheet, wait processing is performed during the time necessary for one sheet, namely for 0.5 seconds. After performing image formation of the third sheet, wait processing is performed during the time necessary for one sheet, namely for 0.5 seconds. After performing image formation of the fourth sheet, wait processing is performed during the time necessary for one sheet, namely for 0.5 seconds. After performing image formation of the fifth sheet, the printing processing ends.

In this case, a sheet discharging destination is determined to be only one finishing apparatus among two finishing apparatuses in Step S108.

When the number of sets is two, the image forming apparatus1performs image formation of the first sheet of the first set, and then performs image formation of the first sheet of the second set. After performing image formation of the second sheet of the first set, image formation of the second sheet of the second set is performed. After performing image formation of the third sheet of the first set, image formation of the third sheet of the second set is performed. After performing image formation of the fourth sheet of the first set, image formation of the fourth sheet of the second set is performed. When image formation of the fifth sheet of the first set is performed and then image formation of the fifth sheet of the second set has been performed, the printing processing ends.

In this case, the sheet discharging destination is determined to be both of two finishing apparatuses in Step S108, and the sheet discharging destination of the sheets of the first set and the sheet discharging destination of the sheets of the second set are distributed to the determined finishing apparatuses respectively.

When the number of sets is three, the image forming apparatus1performs image formation of the first sheet of the first set, and then performs image formation of the first sheet of the second set. After performing image formation of the second sheet of the first set, image formation of the second sheet of the second set is performed. After performing image formation of the third sheet of the first set, image formation of the third sheet of the second set is performed. After performing image formation of the fourth sheet of the first set, image formation of the fourth sheet of the second set is performed. After performing image formation of the fifth sheet of the first set, image formation of the fifth sheet of the second set is performed. After performing image formation of the first sheet of the third set, wait processing is performed during the time necessary for one sheet, namely for 0.5 seconds. After performing image formation of the second sheet of the third set, wait processing is performed during the time necessary for one sheet, namely for 0.5 seconds. After performing image formation of the third sheet of the third set, wait processing is performed during the time necessary for one sheet, namely for 0.5 seconds. After performing image formation of the fourth sheet of the third set, wait processing is performed during the time necessary for one sheet, namely for 0.5 seconds. When image formation of the fifth sheet of the third set has been performed, the printing processing ends.

In this case, the sheet discharging destination is determined to be both of two finishing apparatuses in Step S108, the sheet discharging destination of the sheets of the first set and the sheet discharging destination of the sheets of the second set are distributed to the determined finishing apparatuses respectively, and the sheet discharging destination of the sheets of the third set is determined to be one of the two finishing apparatuses.

When the number of sets is four, the image forming apparatus1performs image formation of the first sheet of the first set, and then performs image formation of the first sheet of the second set. After performing image formation of the second sheet of the first set, image formation of the second sheet of the second set is performed. After performing image formation of the third sheet of the first set, image formation of the third sheet of the second set is performed. After performing image formation of the fourth sheet of the first set, image formation of the fourth sheet of the second set is performed. After performing image formation of the fifth sheet of the first set, image formation of the fifth sheet of the second set is performed. After performing image formation of the first sheet of the third set, image formation of the first sheet of the fourth set is performed. After performing image formation of the second sheet of the third set, image formation of the second sheet of the fourth set is performed. After performing image formation of the third sheet of the third set, image formation of the third sheet of the fourth set is performed. After performing image formation of the fourth sheet of the third set, image formation of the fourth sheet of the fourth set is performed. When image formation of the fifth sheet of the third set is performed and then image formation of the fifth sheet of the fourth set is performed, the printing processing ends.

In this case, the sheet discharging destination is determined to be both of two finishing apparatuses in Step S108, and the sheet discharging destination of the sheets of the first set and the sheet discharging destination of the sheets of the second set are distributed to the determined finishing apparatuses respectively. Similarly, the sheet discharging destination of the sheets of the third set and the sheet discharging destination of the sheets of the fourth set are distributed to the selected finishing apparatuses respectively. The determining processing in Step S108is not, limited to the above as long as finishings are distributed to the finishing apparatuses of the same type uniformly according to the previously-determined method. For example, such distribution is performed in view of the processing speed of the finishing apparatuses.

Returning toFIG. 8, the image-forming-apparatus control section100performs the distributing processing sequence determined in Step S108(Step S109). In Step S109, the distributing processing determined in Step S108is transmitted to the conveyance-unit-apparatus control section600.

The image-forming-apparatus control section100subtracts N from the number X of sets stored in the RAM (Step S110). Then, the image-forming-apparatus control section100refers to the number X of sets to determine whether or not the print output has been completed (Step S114). When the number X of sets is zero or less, it is judged that the print output has been completed.

When the image-forming-apparatus control section100does not judge that the print output has been completed (Step S114: NO), the processing returns to Step S105, and the image-forming-apparatus control section100judges whether or not the speed of continuous printing of the image forming apparatus1is lower than the speed of the continuous processing of the finishing apparatuses.

On the other hand, when the image-forming-apparatus control section100judges that the speed of continuous printing is equal to the speed of continuous processing or less (Step S105: YES), the image-forming-apparatus control section100performs a normal printing sequence without the wait processing or the distributing processing (Step S111). Specifically, in Step S111, the image forming apparatus1continuously performs image formation without performing the abovementioned wait processing, and discharges the sheets to the single finishing apparatus whose type of finishing agrees with the finishing content contained in the sheet information through the conveyance unit apparatus6.

On the other hand, when the image-forming-apparatus control section100does not judge that there are a plurality of finishing apparatuses of the same type (Step S106: NO), and/or when the image-forming-apparatus control section100does not judge the remaining number is equal to N or more (Step S107: NO), the image-forming-apparatus control section100performs a printing sequence with between-sheets wait processing without performing distributing processing (Step S112). Concretely, the image forming apparatus1performs image formation onto the sheet while performing the abovementioned wait processing, and discharges the sheets to the single finishing apparatus via the conveyance unit apparatus6. When the processing speed of the finishing apparatus is low, the image forming apparatus can perform the wait processing so as to space between image forming processings to the sheets depending on the processing speed of the finishing apparatus.

Next, the image-forming-apparatus control section1001subtracts one (1) from the number X of sets (Step S113).

On the other hand, when the image-forming-apparatus control section100judges that the print output has been completed (Step S114: YES), the image-forming-apparatus control section100ends the processing.

FIG. 9shows a flowchart of processing to be performed in the conveyance unit apparatus6when the power source is turned on. The processing shown inFIG. 9is executed by cooperation between the conveyance-unit-apparatus control section600and the programs stored in the storage section650.

As shown inFIG. 9, the conveyance-unit-apparatus control section600firstly judges whether or not a request for the apparatus information from the image forming apparatus has been input (Step S201). When the control section does not judge that the request has been input (Step S201: NO), the processing returns to Step S201, and it is judged whether or not the request for the apparatus information has been input from the image forming apparatus.

When the control section600judges that the request has been input (Step S201: YES), the conveyance-unit-apparatus control section600judges whether or not the printing instruction has been input from the image forming apparatus1(Step S202). When the control section600does not judge that the printing instruction has been input (Step S202: NO), the processing returns to Step S202, and it is judged whether or not the printing instruction has been input from the image forming apparatus1.

When the control section600judges that the printing instruction has been input (Step S202: YES), the conveyance-unit-apparatus control section600turns on power sources of the finishing apparatuses specified by the image forming apparatus1so as to perform finishings (Step S203). In Step S203, it is instructed to turn on the power sources, and at the same time, the finishing apparatuses are required to send the pieces of apparatus information. Then, the conveyance-unit-apparatus control section600judges whether or not these specified finishing apparatuses have been activated and preparation has been completed (Step S204).

When the control section600does not judge that the preparation has been completed (Step S204: NO), the processing returns to Step S204, and it is judged whether or not these specified finishing apparatuses have been activated and preparation has been completed.

When the control section600judges that the preparation has been completed (Step S204: YES), the conveyance-unit-apparatus control section600informs the image forming apparatus1of the completion of preparation (Step S205). In Step S205, the apparatus information is transmitted to the image forming apparatus1concurrently with the completion of preparation.

Next, the conveyance-unit-apparatus control section600judges whether or not printing in the image forming apparatus1has been started (Step S206). When the printing is started, a predetermined signal has been transmitted from the image-forming-apparatus control section100to the conveyance-unit-apparatus control section600.

When the control section600does not judge that the printing has been started (Step S206: NO), the processing returns to Step S206, and it is judged whether or not the printing in the image forming apparatus1has been started.

When the control section600judges that the printing has been started (Step S206: YES), the conveyance-unit-apparatus control section600opens the gates81acorresponding to the finishing apparatuses specified by the image forming apparatus1(Step S207). The gates81awhich should be opened in Step S207are gates of the finishing apparatuses corresponding to the distributing method determined by the image forming apparatus1in Step S108.

Then, the conveyance-unit-apparatus control section600switches the discharging-section switching plates67so that the sheets are conveyed to the finishing apparatuses for which the gates81shave been opened, and performs the conveying processing (Step S208). The conveyance-unit-apparatus control section600judges whether or not sheet discharge to the specified finishing apparatuses has been completed (Step S209).

When the control section600does not judge that the sheet discharge has been completed (Step S209: NO), the processing returns to Step S208.

When the control section600judges that the sheet discharge has been completed (Step S209: YES), the conveyance-unit-apparatus control section600closes the gates81acorresponding to the finishing apparatuses specified by the printing instruction from the image forming apparatus1(Step S210.)

The conveyance-unit-apparatus control section600judges whether or not print output has been completed (Step S211). When the control section600does not judge that the print output has been completed (Step S211: NO), the processing returns to Step S207, and the conveyance-unit-apparatus control section600opens the gates81acorresponding to the finishing apparatuses specified by the printing instruction from the image forming apparatus1.

When the control section600judges that the print output has been completed (Step S211: YES), the processing ends.

Next, a flow of processing of the whole image forming system1000when the processings shown inFIGS. 8 and 9are performed will be described.FIG. 10shows the flow of processing in the image forming system100. In an example explained below, it is assumed that the finishing apparatuses placed in the placement sections80are two finishing apparatuses (first finishing apparatus3and the second finishing apparatus4) of the same type, the number of sets according to the job to be executed is two, and the number of sheets to be output is two. It is also assumed that the processing speeds of the first finishing apparatus and the second finishing apparatus are the same value of 60 ppm, and the speed of continuous printing of the image forming apparatus1is 120 ppm. In this case, the image-forming-apparatus control section100judges that in Step S108, image formation of the first sheet of the first set is performed and then image formation of the first sheet of the second set is performed, and image formation of the second sheet of the first set is performed and then image formation of the second sheet of the second set is performed. The image-forming-apparatus control section100also judges that finishing for the sheets of the first set is performed by the first finishing apparatus, and finishing for the sheets of the second set is performed by the second finishing apparatus. Moreover, the image-forming-apparatus control section100gives the sheet ID “1a” to the first sheet of the first set, and gives the sheet. ID “1b” to the first sheet of the second set. Similarly, the image-forming-apparatus control section100gives the sheet ID “2a” to the second sheet of the first set, and gives the sheet ID “2b” to the second sheet of the second set.

As shown inFIG. 10, the image-forming-apparatus control section100firstly requests the conveyance unit apparatus6to send the apparatus information regarding each of the finishing apparatuses respectively placed in the placement sections80, similarly to Step S101(Step S11).

The conveyance-unit-apparatus control section600confirms the connection states of the finishing apparatus respectively placed in the placement sections80by using the connection detection sensors85, turns on the power source of each of the finishing apparatuses by the power supply section604, and requests for the apparatus information regarding each of the finishing apparatuses via the serial communication section602, similarly to Step S203(Step S12).

The first-finishing-apparatus control section300and the second-finishing-apparatus control section400transmit the pieces of apparatus information to the conveyance unit apparatus6through the serial communication section301and the serial communication section401respectively (Step S13, Step S14).

The conveyance-unit-apparatus control section600transmits the pieces of apparatus information obtained in Step S13and Step S14to the image forming apparatus1, similarly Step S205(Step S15).

The image-forming-apparatus control section100transmits the signal indicating that printing has been started to the conveyance unit apparatus6(Step S16). Then, the image-forming-apparatus control section100makes the feeding tray13aor the feeding unit5feed the sheet corresponding to the sheet ID “1a” to start image formation, and transmits the signal indicting that the sheet whose sheet ID is “1a” has been fed, to the conveyance unit apparatus6(Step S17).

The conveyance-unit-apparatus control section600judges which of the gates81ashould be opened based on the received sheet ID, opens the gate81acorresponding to the first finishing apparatus indicated by the sheet ID “1a”, and switches the discharging-section switching plates67, similarly to Step S207(Step S18). Then, the conveyance-unit-apparatus control section600transmits information of the sheet ID “1a” to the first finishing apparatus3(Step S19).

The image-forming-apparatus control section100makes the feeding tray13aor the feeding unit5feed the sheet corresponding to the sheet ID “1b” to start image formation, and transmits the signal indicating the sheet whose sheet ID is “1b” has been fed, to the conveyance unit apparatus (Step S20). Then, the conveyance-unit-apparatus control section600transmits information of the sheet ID “1b” to the second finishing apparatus4(Step S21).

The image-forming-apparatus control section100transmits the signal indicating that the sheet whose sheet ID is “1a” has been discharged to the conveyance apparatus6, with respect to the conveyance apparatus6(Step S22). The conveyance-unit-apparatus control section600transmits the signal indicating the discharge of the sheet whose sheet ID is “1a” to the first finishing apparatus3(Step S23).

The first-finishing-apparatus control section300informs the conveyance unit apparatus6of completion of discharge of the sheet whose sheet ID is “1a” by using the sensor provided in the introducing port30a(Step S24). The conveyance-unit-apparatus control section600informs the image forming apparatus1of completion of discharge of the sheet whose sheet ID is “1b” (Step S25). Next, the conveyance-unit-apparatus control section600judges which of the gates81ashould be opened based on the sheet ID of the sheet to be discharged after discharge of the sheet whose sheet ID is “1a” (namely, based on the sheet ID “1b”), closes the gate81acorresponding to the first finishing apparatus3, opens the gate81acorresponding to the second finishing apparatus4, and switches the discharging-section switching plates67(Step S26).

Then the processing shifts to processing shown inFIG. 11, and the image-forming-apparatus control section100transmits the signal indicating that the sheet whose sheet ID is “1b” has been discharged to the conveyance unit apparatus6, with respect to the conveyance unit apparatus (Step S27). The conveyance-unit-apparatus control section600transmits the signal indicating the discharge of the sheet whose sheet ID is “1b” to the second finishing apparatus4(Step S28).

The second-finishing-apparatus control section400informs the conveyance unit apparatus6of the completion of discharge of the sheet whose sheet ID is “1b” (Step S29). The conveyance-unit-apparatus control section600informs the image forming apparatus1of the completion of discharge of the sheet whose sheet ID is “1b” (Step S30).

Then, the image-forming-apparatus control section100makes the feeding tray13aor the feeding unit5feed the sheet to which the sheet ID has been given to start image formation, and transmits the signal indicating that the sheet whose sheet ID is “2a” has been fed to the conveyance unit apparatus6(Step S31).

The conveyance-unit-apparatus control section600judges which of the gates81ashould be opened on the basis of the received sheet ID, opens the gate81acorresponding to the first finishing apparatus3which the sheet ID “2a” indicates, closes the gate81acorresponding to the second finishing apparatus4, and switches the discharging-section switching plates67(Step S32). Then, the conveyance-unit-apparatus control section600transmits information of the sheet ID “2a” to the first finishing apparatus3.

The image-forming-apparatus control section100makes the feeding tray13aor the feeding unit5feed the sheet corresponding to the sheet ID “2b” to start image formation, and transmits the signal indicating that the sheet whose sheet ID is “2b” has been fed to the conveyance unit apparatus6(Step S34). Then, the conveyance-unit-apparatus control section600transmits information of the sheet ID “2b” to the second finishing apparatus4(Step S35).

The image-forming-apparatus control section100transmits the signal indicating that the sheet whose sheet ID is “2a” has been discharged to the conveyance unit apparatus6, with respect to the conveyance unit apparatus (Step S36). The conveyance-unit-apparatus control section600transmits the signal indicating the discharge of the sheet whose sheet ID is “2a” to the first finishing apparatus3(Step S7).

The first-finishing-apparatus control section300informs the conveyance unit apparatus6of completion of discharge of the sheet whose sheet ID is “2a” (Step S38). The conveyance-unit-apparatus control section600informs the image forming apparatus1of completion of discharge of the sheet whose sheet ID is “2a” (Step S39) Next, the conveyance-unit-apparatus control section600judges which of the gates81ashould be opened based on the sheet ID of the sheet to be discharged after discharge of the sheet whose sheet ID is “2a”, closes the gate81acorresponding to the first finishing apparatus3, opens the gate81acorresponding to the second finishing apparatus4, and switches the discharging-section switching plates67(Step S40).

The image-forming-apparatus control section100transmits the signal indicating that the sheet whose sheet ID is “2b” has been discharged to the conveyance unit apparatus6, with respect to the conveyance unit apparatus6(Step S41). The conveyance-unit-apparatus control section600transmits the signal indicating the discharge of the sheet whose sheet ID is “2b” to the second finishing apparatus4(Step S42).

The second-finishing-apparatus control section400informs the conveyance unit apparatus6of completion of discharge of the sheet whose sheet ID is “2b” (Step S43). The conveyance-unit-apparatus control section600informs the image forming apparatus1of completion of discharge of the sheet whose sheet ID is “2b” (Step S44).

As described above, according to the image forming system of the present embodiment, when the number of sets is plural according to the job to be executed and a plurality of finishing apparatuses which can perform finishings corresponding to the job are connected to the conveyance unit apparatus, it is judged which of the finishing apparatuses should perform finishing to each sheet. Since the conveyance unit apparatus performs the control to discharge the sheets to the judged finishing apparatuses, even when the speed of continuous printing of the image forming apparatus is faster than the processing speed of the finishing apparatus, finishings can be shared so that productivity of continuous printing is improved. Moreover, even when sheet-jam occurs in one finishing apparatus, other apparatuses can perform finishings so that downtime is reduced.

By judging which of the finishing apparatuses should performs finishing to each sheet on the basis of the number of sets and the speed of continuous printing of the image forming apparatus, even when the multiple sets are to be output, the finishings can be distributed optimally. By performing this distribution uniformly depending on the number of the finishing apparatuses, productivity can be improved without stopping continuous printing of the image forming apparatus.

When the speed of continuous printing of the image forming apparatus exceeds the processing speed of the finishing apparatuses, by executing the wait processing in a predetermined condition, finishing can be performed so as to be suited to a given situation. The wait processing may be performed similarly even when the remaining number of sets according to the job is not equal to or above the number of the finishing apparatuses.

Since the information for identifying the finishing apparatus which should perform finishing can be contained in the sheet ID, the conveyance unit apparatus can judge which of the finishing apparatuses should discharge the sheets on the basis of the sheet ID.

Incidentally, the description of the above-mentioned embodiment is an example of the preferred image forming system according to the present invention, and the present invention is not limited to that. For example, as other computer readable media other than the storage section of the present embodiment, a nonvolatile memory including a Secure Digital (SD) card and a flash memory such as a Universal Serial Bus (USB) memory, and a portable recording medium such as CD-ROM may be applied to the present invention. It is also possible to superimpose various pieces of data such as data of the programs and audio data on carrier wave to provide it via the communication line.

In addition, also detailed operations of the image forming system can be change appropriately without departing from the spirit of the present invention.

All of the disclosures including the claims, the patent specification, the attached drawings and the abstract of Japanese Patent Application No. 2009-158350 filed on Jul. 3, 2009 are herein incorporated by reference.