JP7487530B2 - Sheet conveying device and image forming system - Google Patents

Description

The present invention relates to a sheet conveying device and an image forming system.

There is known an image forming system that includes an image forming device that ejects liquid onto a sheet-like medium to form an image, a sheet transport device that transports the medium on which the image has been formed, and a post-processing device that performs a predetermined post-processing on the transported medium.

In recent years, there has been an increasing demand for improved productivity, including sheet post-processing, using image forming devices capable of forming images at high speed, particularly in image forming systems used in the commercial field. When the speed at which the post-processing device accepts sheets is slower than the image formation speed, the post-processing speed can cause a decrease in the productivity of the image formation process. In such cases, a sheet conveying device is placed between the image forming device and the post-processing device as an intermediary conveying device.

In order to improve the productivity of image formation, a technology is known in which multiple transport paths are arranged in parallel between an image forming unit and a media discharge unit that discharges media after image formation, and the media after image formation is distributed to the multiple transport paths and sent downstream in the order of transport (see Patent Document 1).

The technology disclosed in Patent Document 1 arranges transport paths in parallel to dry media within an image forming device. In this case, even media that do not require a long time to dry are distributed to multiple transport paths. Since the parallel transport paths are longer than a transport path that is not distributed, depending on the degree to which drying is required, even media that can be transported on a shorter transport path will be transported using a long transport path, resulting in a problem of reduced productivity in image formation.

The present invention aims to provide a sheet transport device that improves productivity in transporting sheets after image formation.

In order to solve the above problems, the present invention relates to a sheet conveying device having a plurality of conveying paths arranged in parallel and conveying a conveyed sheet from the upstream side to the downstream side in the conveying direction, the sheet conveying device comprising: a drying time calculation means for calculating a drying time of the conveyed sheet based on sheet-related information related to the conveyed sheet; a conveying path selection means for selecting one of the plurality of conveying paths as the conveying path for conveying the sheet; and a sheet guiding means for guiding the sheet to the selected conveying path, wherein the conveying path selection means selects the conveying path based on the drying time of the sheet.

This invention can improve the productivity of sheet transport after image formation.

FIG. 1 is a schematic diagram showing an outline of a print system as an embodiment of an image forming system according to the present invention; FIG. 2 is a schematic side view of a printer constituting the printing system. FIG. 2 is a schematic side view of an intermediate conveying device constituting the sheet conveying device according to the present invention. FIG. 2 is a schematic side view of a post-processing device included in the printing system. FIG. FIG. 4 is an enlarged explanatory diagram of a transport branching section provided in the relay transport device. FIG. 4 is an enlarged explanatory diagram of a transport branching section provided in the relay transport device. FIG. 4 is an enlarged explanatory diagram of a transport branching section provided in the relay transport device. FIG. 4 is an enlarged explanatory diagram of a transport branching section provided in the relay transport device. FIG. 4 is an enlarged explanatory diagram of a transport branching section provided in the relay transport device. FIG. 2 is a diagram showing the configuration of a control unit of the printer. FIG. 4 is a configuration diagram of a control unit of the relay transport device. FIG. 2 is a configuration diagram of a control unit of the post-processing device. 10 is a flowchart showing a flow of a control transport process in the relay transport device. 10 is a flowchart showing a flow of a control transport process in the relay transport device. 10 is a flowchart showing a flow of a control transport process in the relay transport device.

Below, a sheet conveying device and an image forming system according to an embodiment will be described with reference to the drawings. In the following description, the same reference symbols are used for equivalent parts, and duplicate descriptions will be omitted as appropriate.

<Overall composition>
The following describes an overview of a print system 1000 as an embodiment of a sheet conveying device and an image forming system including the same according to the present invention. As shown in Fig. 1, the print system 1000 is configured to connect a printer 100 as an embodiment of an image forming device, an intermediary conveying device 200 as an embodiment of a sheet conveying device, and a post-processing device 300, and to convey paper (sheet) P in that order.

In the print system 1000, the paper P on which an image is formed by the image forming process in the printer 100 is conveyed to the post-processing device 300 via a conveying path appropriately selected from among multiple conveying paths provided in the relay conveying device 200 as a sheet conveying device. The post-processing device 300 performs a predetermined post-processing on the paper P conveyed from the relay conveying device 200 and discharges the paper P after post-processing. The printer 100 is connected to the relay conveying device 200 as a device on the upstream side in the conveying direction, and the post-processing device 300 is connected to the relay conveying device 200 as a device on the downstream side in the conveying direction, to form the print system 1000 as an image forming system. Below, the printer 100, the relay conveying device 200, and the post-processing device 300 will be individually described with reference to the drawings.

<Outline of Printer 100>
Next, an overview of the printer 100 will be described with reference to Fig. 2. As shown in Fig. 2, the printer 100 has an image forming unit 101, a sheet storage unit 102 as a paper feed tray, a sheet supply unit 103 as a paper feed means, a sheet conveying unit 104 as a sheet conveying means, a reverse conveying path switching unit 106 as a conveying path switching means, an original reading unit 108 as an original reading means, a reverse conveying path 109 for forming images on both sides of the paper P, and a control unit 500 as a control means. Details of the control unit 500 will be described later.

The image forming unit 101 as an image forming means is composed of liquid ejection heads having ejection ports (nozzles) for ejecting liquid ink of four colors, for example, Y (yellow), M (magenta), C (cyan), and B (black). A liquid ejection head is provided separately for ejecting liquid ink of each color. Liquid ink is supplied to each liquid ejection head constituting the image forming unit 101 by driving a supply pump connected to an ink cartridge. Therefore, liquid ink is supplied to each liquid ejection head by the supply pump from an ink cartridge containing liquid ink of each color. The ink cartridges of each color are detachably attached to a cartridge loading unit equipped in the image forming unit 20.
The sheet storage unit 102 includes a plurality of sheet cassettes for stacking and storing sheet-like media, namely, paper P. The paper P refers to any medium on which an image can be formed by adhering ink thereto and which can be curved and transported, such as paper (paper), overhead projector sheets, thread, fiber, fabric, leather, metal, or plastic.

The sheet supply unit 103 is composed of a pickup roller that picks up the paper P stored in the sheet storage unit 102, and a separation roller and a reverse roller that separate and transport the picked up paper P one sheet at a time.

The sheet transport unit 104 is made up of multiple transport roller pairs, each consisting of a transport roller and a spur, arranged along the transport path for the paper P. Each transport roller pair is rotated by a transport drive unit and transports the paper P in a predetermined direction at a predetermined transport speed. Note that one of the transport roller pairs is not limited to a spur, but may be any rotating body that has a contact area with the paper P as small as the spur and partially contacts the paper P, and may be, for example, a roller with an abrasive grain surface.

The reverse transport path switching unit 106 is composed of a switching claw for guiding the paper P to the reverse transport path 109 for inverting the image formation side of the paper P and transporting it to the image forming unit 101. When forming images on both sides of the paper P, the paper P with an image formed on its first side in the image forming unit 101 is once transported downstream in the transport direction until the rear end of the paper P passes the reverse transport path switching unit 106. After that, the transport path is switched by the reverse transport path switching unit 106, and the paper P is transported in reverse upstream in the transport direction to join the transport path leading from the reverse transport path 109 to the image forming unit 101. The image forming unit 101 then forms an image on the second side (the side opposite the first side) of the inverted paper P that faces the image forming unit 101.

<Outline of relay transport device 200>
Next, an overview of the relay conveying device 200 as a sheet conveying device will be described with reference to FIG. 3. The paper P discharged from the printer 100 is conveyed to an entrance guide plate 201 of the relay conveying device 200 as a sheet conveying device, and is conveyed into the relay conveying device 200 by an entrance conveying roller 211 as a conveying means. The entrance conveying roller 211 is composed of a pair of driving rollers 211a and a driven spur roller 211b. The spur roller 211b is disposed below the conveying surface, and each conveying path has a similar configuration. Furthermore, the guide plates on the driving roller side and the spur roller side are configured with a diaphragm (not shown) or the like so that the contact area with the paper P is reduced, thereby preventing the image on the printing surface from being "blurred" or "scraped".

The paper P transported to the relay transport device 200 is branched by the transport branching section 210a into one of the multiple transport paths: an upper transport path (the length of the transport path in the transport direction is medium), another straight transport path (the length of the transport path in the transport direction is the shortest), and another lower transport path (the length of the transport path in the transport direction is the longest). The configuration of the branching section will be described later.

The paper P to be transported to the upper transport path is guided to the upper transport path by the upper transport roller pair 219, which is a set of a drive roller and a spur roller as a transport means. The upper transport roller pair 219 transports the paper by driving the upper transport motor 620 (see Figure 15). The upper transport roller pair 219 operates to transport the paper P by the length (length unit) of one sheet of paper P, in accordance with the length dimension of the paper P in the transport direction.

The paper P to be transported to the straight transport path is guided to the straight transport path by the straight transport roller pair 217, which is a set of a drive roller and a spur roller as a transport means. The straight transport roller pair 217 transports the paper by driving the straight transport motor 621 (see Figure 12). The straight transport roller pair 217 operates to transport the paper P by the length (length unit) of one sheet of paper P, in accordance with the length dimension of the paper P in the transport direction.

The paper P to be transported to the lower transport path is guided to the lower transport path by the lower transport roller pair 222, which is a set of a drive roller and a spur roller as a transport means. The lower transport roller pair 222 transports the paper by driving the lower transport motor 622 (see Figure 12). The lower transport roller pair 222 operates to transport the paper P by the length (length unit) of one sheet of paper P, in accordance with the length dimension of the paper P in the transport direction.

By providing an entrance rotation mechanism 206 and an exit rotation mechanism 207 in the lower transport path, which can rotate the transport direction of paper P by 90 degrees to store it in a landscape orientation instead of a portrait orientation, and then rotate it in the opposite direction by 90 degrees to return it to its original orientation, the number of sheets of paper P that can be stored in the lower transport path can be increased.

<Outline of post-processing device 300>
Next, an overview of the post-processing device 300 will be described with reference to Figures 4 and 5. The paper P discharged from the relay conveying device 200 is conveyed to an entrance guide plate 301 of the post-processing device 300, and is conveyed into the post-processing device 300 by a pair of conveying rollers 302 and 303 as a conveying means. The paper P conveyed to the post-processing device 300 is branched by a branching claw 304 into a sorting conveying path and a staple conveying path.

The paper P transported to the sorting transport path is discharged onto the stacking tray 351 by a pair of transport rollers 305 and a pair of paper discharge rollers 311, which serve as transport means. When discharging, the return drive roller 361 returns the paper to the end fence side of the stacking tray, and the paper alignment mechanism 362 aligns the paper vertically to the transport direction.

The paper P conveyed to the staple conveying path passes through the staple sensor 367 and is discharged to the staple tray 365 by the pair of conveying rollers 309 as a conveying means, and its rear end is abutted against the reference fences 369, 370 by the tapping roller 310 and the leading edge stopper 363 for alignment. The paper P is then aligned in the width direction by the jogger fence 372, its rear end is pressed and aligned by the paper rear end alignment device 371, stapled to the desired position by the stapler 368, and discharged to the stacking tray 351 by the post-stapling release claw 366 and the pair of paper discharge rollers 311.

Next, the pre-stack transport control of the pre-stack unit 3a will be described with reference to FIG. 5. When a stack of sheets Pt is formed from a plurality of sheets P, the first sheet of the stack of sheets Pt passes the entrance sensor 341 and moves a predetermined distance, after which the branch claw 304 is switched by the switching motor to transport it to the staple side. Then, after the first sheet moves a further predetermined distance, the pre-stack branch claw 350 is switched by the branch claw switching motor and is guided to the first transport path (the transport roller pair of the drive roller 357 and the driven roller 356). After moving a further predetermined distance, the first sheet of the stack of sheets Pt reaches the stop position. When it reaches the stop position, the drive roller 357 is stopped to stop the transport of the first sheet P.

After the second sheet of the "paper stack Pt" passes through the entrance sensor 341 and moves a specified distance, the pre-stack branch claw 350 is switched by the branch claw switching motor, and the sheet P (second sheet) is guided to the second transport path (the transport roller pair of the drive roller 358 and the driven roller 359). The sheet P (second sheet) is transported directly on the second transport path to the detection unit 381, which detects the stop position. After that, when the sheet P reaches the stop position, this is detected and the transport pressure of the drive roller 358 and the driven roller 359 is released. The transport pressure may be released directly from the drive roller 358, or the transport pressure of the drive roller 358 and the driven roller 359 themselves may be released.

After the third sheet of the "paper stack Pt" passes through the entrance sensor 341 and moves a predetermined distance, the pre-stack branch claw 350 is switched by the branch claw switching motor and guided to the third transport path (the transport roller pair of the drive roller 352 and the driven roller 353). The paper P (third sheet) is transported as is to the detection unit 380, which detects the paper position by the drive roller 352. When the paper P is detected at the paper position, the drive motor operates the drive roller of the first transport path to start the movement of the paper P on the first transport path. At the same time, the transport pressure of the second transport path is turned ON to start the movement of the paper P on the second transport path. When all the papers P are overlapped, the drive as a transport means and the transport roller pair 345 of the driven roller 355 and the transport roller pair 309 transport the paper P to the staple tray.

For even-numbered sheets of paper P in the "paper stack Pt", after passing the entrance sensor 341 and moving a specified distance, the pre-stack branch claw 350 is switched by the branch claw switching motor and the paper P is guided to the second transport path. The paper P is transported as is until it is detected by the detection unit 381 at the stop position. When the paper P is detected at the stop position, the transport pressure of the drive roller 358 and the driven roller 359 is released. The transport pressure may be released directly from the drive roller 358, or the transport pressure of the guide plate 383 itself may be released.

For odd-numbered sheets of paper P in the "paper stack Pt", after passing the entrance sensor 341 and moving a specified distance, the pre-stack branch claw 350 is switched by the branch claw switching motor and guided to the third transport path. The paper P is transported as is, and is transported to a detection unit 380 that detects the paper position by a drive roller 352 and a driven roller 353. When the paper position is detected, the transport pressure of the second transport path is turned ON, and the movement of the paper P on the second transport path begins. All of the paper P is driven to the staple tray in a synchronized manner, and is transported to the staple tray by a pair of transport rollers 354, 309.

<Configuration of conveyor branch section>
Next, a description will be given of the configuration of the conveying section 210 (conveying branching section 210a, conveying junction section 210b, conveying bending sections 210c, 210d, 210e, and 210f as sheet guiding means) included in the relay conveying device 200 according to this embodiment. The conveying branching section 210a illustrated in Figures 6, 7, and 8 is an example of a guide configuration for guiding the paper P discharged from the printer 100 to the multiple conveying paths included in the relay conveying device 200.

In the conveying branch section 210a, multiple drive rollers 231, 232, 233, and 234 are arranged, and multiple spur rollers 230 that face these drive rollers 231, 232, 233, and 234, as well as multiple spur rollers 230 that do not face each other and can rotate freely, are arranged.

The transport branch section 210a, which is positioned to switch the transport path of the paper P transported from the printer 100, is equipped with a lower transport switching claw 235, an upper transport switching claw 236, and a guide plate 237 that opens the transport path to make it easier to remove the paper P when an abnormality in the paper P is detected and transport is stopped. The lower transport switching claw 235 and the upper transport switching claw 236 are moved to a position where they guide the paper P to a specified transport path by rotating around a rotation axis (not shown) by a first entrance branch motor 627 and a second entrance branch motor 628.

Figure 6 illustrates an example of guiding paper P to a straight transport path as a first transport branch path. Note that while FIG. 6(a) uses reference numerals to indicate each component, FIG. 6(b) omits reference numerals to illustrate the manner in which paper P is guided. The same applies to FIGS. 7 and 8 below. As shown in FIG. 6(a), the lower transport switching claw 235 and the upper transport switching claw 236 are operated by the first entrance branch motor 627 and the second entrance branch motor 628 so as to be positioned in a direction that guides paper P to the straight transport path. If paper P is in a state in which it is guided as shown in FIG. 6(b), there is no need to operate the lower transport switching claw 235 and the upper transport switching claw 236.

FIG. 7 illustrates an example in which the paper P is guided to the upper transport path serving as the second transport branch path.
As shown in Figure 7 (a), when guiding paper P to the upper transport path, the lower transport switching claw 235 and the upper transport switching claw 236 are operated by the first inlet branch motor 627 and the second inlet branch motor 628 so as to be positioned in a direction that guides the paper P to the upper transport path.

As shown in FIG. 7B, when guiding paper P to the upper transport path, the lower transport switching claw 235 is in the same position as in the straight transport. The upper transport switching claw 236 is rotated so that the upstream side of the upper transport switching claw 236 is positioned downward so as to guide paper P to the upper transport path. When paper P is transported along the upper surface of the upper transport switching claw 236, there is a possibility that it may come into contact with the printing surface (image formation surface). To avoid this, a freely rotatable spur roller 230 is also arranged on the upper transport switching claw 236. The spur roller 230 is arranged at a distance such that the leading edge of paper P does not come into contact with the upper transport switching claw 236.

Figure 8 illustrates an example of guiding paper P to the lower transport path, which serves as the third transport branch path. As shown in Figure 8 (a), when guiding paper P to the lower transport path, the lower transport switching claw 235 is operated by the first entrance branch motor 627 in a direction to guide paper P to the lower transport path.

As shown in FIG. 8B, the lower transport switching claw 235 is rotated so that the upstream side of the lower transport switching claw 235 is positioned upward so as to guide the paper P to the lower transport path. When the paper P is transported along the underside of the lower transport switching claw 235, there is a possibility that the curved transport guide surface opposite the lower transport switching claw 235 may come into contact with the printing surface more frequently. To avoid this, a freely rotatable spur roller 230 is also arranged on the curved transport guide surface opposite the lower transport switching claw 235. The spur roller 230 is arranged at a distance such that the leading edge of the paper P does not come into contact with the curved transport guide surface opposite the lower transport switching claw 235.

Figure 9 is a diagram showing the configuration of the transport junction 210b (branch junction) located at the junction of the straight transport path, the upper transport path, and the lower transport path. The transport junction 210b is configured to transport paper P using guide plates 242, 243, and 244 that open the transport path to make it easier to remove paper P when an abnormality in paper P is detected and transport is stopped, and drive rollers 232, 233, 234, 240, and 241 that transport paper P. In addition, multiple spur rollers 230 that face each drive roller and multiple spur rollers 230 that do not face each other are also arranged.

The spur rollers 230 are positioned at a distance such that the paper P does not come into contact with the guide plate 244. In addition, at the point where the lower transport path joins the straight transport path, a drive roller 241, which is a spur roller larger than the other spur rollers 230, is positioned so that the leading edge of the paper P can be smoothly transferred between the drive roller 234 and the drive roller 241.

Figure 10 is a diagram showing the configuration of the transport bends 210c, 210d, 210e, and 210f, which are arranged at the turns of the upper transport path or the lower transport path. The transport bends are configured to transport paper P by drive rollers 233 and 234. In addition, multiple spur rollers 230 that face each drive roller and multiple spur rollers 230 that do not face each other are also arranged.

The pair of drive rollers 211a provided in the relay conveying device 200 shown in FIG. 3 is the same as the drive roller 231 shown in FIG. 6 to FIG. 10. Similarly, the rollers marked with the reference symbols 219a and 233, 217a and 232, 222a and 234, 219b, 217b, 222b and 230, and 215a and 240 correspond to those having the same functions.

<Control Configuration of Print System 1000>
Next, the control configuration of the print system 1000 according to this embodiment will be described with reference to Fig. 11 to Fig. 13. Fig. 11 is a diagram illustrating an example of the functional configuration of a control unit 500 which is the control configuration of the printer 100.

The control unit 500 includes a CPU (Central Processing Unit) 501 that controls the entire printer 100, a ROM (Read Only Memory) 502 that stores programs executed by the CPU 501 and other fixed data, a RAM (Random Access Memory) 503 that temporarily stores image data (print data) and the like, a non-volatile memory that is a storage means for retaining data even when the power supply to the device is cut off, an NVRAM (Non-Volatile Random Access Memory) 504 that is a storage means, and an ASIC (Application Specific Integrated Circuit) 505 that processes various signal processes and image processing such as sorting for image data, and processes input/output signals for controlling the entire device. Circuit 505 and a scanner control unit 506 that performs image reading by the document reading unit 108 and data processing of the read images.

The control unit 500 also includes an I/F (Interface) 507 as an interface for sending and receiving data and signals used when receiving data from an external device (relay conveying device 200), a head drive control unit 508 and a head driver 509 for driving and controlling the recording head provided in the image forming unit 101, and motor drive units 511-515, 531 including motor drivers for independently driving various motors (drive sources) such as a main scanning motor 121 for main scanning the carriage carrying the recording head, a sub-scanning motor 131 for rotating the conveying belt, a conveying motor 526 for rotating the rollers that make up the sheet conveying unit 104, a paper feed motor 45 for rotating the paper feed rollers that make up the sheet supply unit 103, and a double-sided conveying motor 524 for rotating the reverse conveying path switching unit 106.

The sheet supply unit 103 also includes an electromagnetic clutch for independently rotating the rollers that make up the sheet supply unit 103, an electromagnetic clutch for independently driving the conveying paths 401, and a clutch driver 516 for driving clutches 525 such as a branch plate solenoid that swings the reverse conveying path switching unit 106 between the discharge position, the double-sided position, and the straight discharge position.

The control unit 500 also includes an I/O 521 for receiving detection signals from a temperature and humidity sensor 534 that detects temperature and humidity as environmental conditions, and detection signals from various sensors such as an image start sensor and an image end sensor (not shown), and is also connected to an operation panel 522 for inputting and displaying information required for this device.

Here, a temperature and humidity sensor 534 that detects temperature and humidity is provided at any location in the printer 100. By providing the temperature and humidity sensor 534 near the sheet supply unit 103 that holds the paper P, which is the recording medium (transported object), it is possible to detect the temperature and humidity of the surrounding area where the paper P being fed is placed, and to obtain the amount of moisture contained in the paper P being fed, enabling more accurate curl prevention control.

In addition, by providing the temperature and humidity sensor 534 near the paper P, which is the recording medium on which image formation has been completed, it is possible to detect the temperature and humidity of the surrounding area in which the paper P is placed after image formation has been completed, and the dry state of the paper P after image formation can be obtained, allowing for more accurate curl prevention control.

The temperature and humidity sensor 534 can also be provided at a location where it can detect the temperature and humidity around the paper P fed from the sheet storage unit 102, etc., or at a location where it can detect the temperature and humidity of the paper P that is re-fed in the case of double-sided printing.

When the control unit 500 reads an original image using the image reading unit 111, it processes the read image and stores it in a buffer in the scanner control unit 506. When it receives print data or the like from an external host side such as an information processing device such as a personal computer, an image reading device such as an image scanner, or an imaging device such as a digital camera via an I/F 507 with the outside, it stores the data in a receive buffer included in the I/F 507.

The CPU 501 then reads and analyzes image data from the scanner control unit 506 and I/F 507, performs the necessary image processing, data sorting processing, etc. in the ASIC 505, and transfers the print image data to the head drive control unit 508. Note that dot pattern data for outputting an image based on data from the outside may be generated by storing font data in the ROM 502, for example, or the image data may be expanded into bitmap data by a printer driver on the external host side and transferred to the image forming device.

When the head drive control unit 508 receives image data during one operation cycle of each recording head of the image forming unit 101, it transfers that amount of image data to the head driver 509, which selectively applies the required drive waveform to the actuator means of the recording head based on the image data to drive it, causing droplets to be ejected from the required nozzles of each recording head. After image formation is completed, the paper P is sent to the relay conveying device 200, which is the destination.

<Control configuration of relay transport device 200>
Next, the control unit 600 provided in the intermediary transport device 200, which is a part of the control configuration in the print system 1000 according to this embodiment, will be described with reference to FIG.

The control unit 600 includes a CPU 601 that controls the entire relay conveying device 200, a ROM 602 that stores the programs executed by the CPU 601 and other fixed data, and a RAM 603 that temporarily stores image data to be formed on the paper P, etc.

The control unit 600 also includes an upstream device I/F 604 and a peripheral device I/F 605 as interfaces for sending and receiving data and signals used when receiving data from external devices (printer 100, post-processing device 300).

The relay conveying device 200 is provided with motor driving units 610-618 including motor drivers for independently driving various motors (driving sources) 620-628 that rotate and drive rollers for conveying or stopping the conveying of the paper P conveyed inside the relay conveying device 200. The relay conveying device 200 also includes a clutch driving unit 619 and clutches 629 for separately rotating and driving the rollers for conveying or stopping the conveying of the paper P conveyed inside the relay conveying device 200.

The control unit 600 has a configuration that controls the start and stop of rotational driving of the rollers that make up the straight conveying roller pair 217, the upper conveying roller pair 219, and the lower conveying roller pair 222. Therefore, the control unit 600 corresponds to a conveying control means. Based on the conveying control of the control unit 600, the timing of conveying and stopping the conveying of the paper P and the conveying amount are controlled.

The control unit 600 also receives notification of the printing rate for each sheet of paper P from the printer 100, which is an upstream device, using the paper information as sheet-related information for the sheet of paper P, and calculates the dryness (drying time). Then, based on the dryness, etc., it selects a transport path to guide the sheet of paper P, and also controls the transport order. Therefore, the control unit 600 also constitutes a transport path selection means.

<Control Configuration of Post-Processing Device 300>
Next, the control unit 700 provided in the post-processing device 300, which is a part of the control configuration in the print system 1000 according to this embodiment, will be described with reference to FIG.

The control unit 700 inputs signals from each sensor and each switch in the post-processing device 300 to the CPU 702 via the I/O interface 701. In response to the input signals, the CPU 702 controls a drive motor 703 for rotating the return drive roller 361, an up-down motor 704 for raising and lowering the stacking tray 351, a shift motor 714 for shifting the stacking tray 351, a solenoid 705 for switching the branch claw 304, a tapping solenoid 706 for driving the tapping roller 310, a conveying motor 707 for driving the conveying roller pairs 303, 305, 309, etc., a paper discharge motor 708 for driving the paper discharge roller pair 311, a stapler motor 709 for driving the stapler 368, a discharge motor 710 for driving a discharge belt for sending out the paper P on the staple tray 365, a stapler movement motor 711 for moving the stapler 368 to adjust the binding position of the paper P, and a jogger motor 712 for driving the jogger fence 372. The CPU 702 also controls the driving of the punch drive motor 713, which performs the punching process.

<Operation flow of the relay transport device 200>
Next, an example of a process for determining a transport route of the paper P in the relay transport device 200 according to the present embodiment will be described. FIGS. 14 to 16 illustrate a flow of a process executed in the control unit 600 included in the relay transport device 200.

First, the printer 100 determines whether the paper P on which an image has been formed has been transported to the relay transport device 200 based on the detection result of the entrance sensor 213 (S1701). The process of S1701 is looped until the entrance sensor 213 is ON (a state in which the paper P is detected) (S1701: N). When the entrance sensor 213 is ON (S1702: Y), the printer 100 notifies the paper P (hereinafter, the paper P to be processed will be referred to as "paper Pn" to distinguish it from other papers P), and the "drying time" is calculated as the degree of dryness for drying the paper Pn from the paper information as sheet-related information (S1702). The paper information also includes information indicating the transport order of the paper Pn that is being processed among the multiple papers P included in one job. As a result, the transport order of the paper Pn is controlled by the control unit 600 in the subsequent processing.

The drying time is calculated by the control unit 600 included in the intermediary transport device 200. Therefore, the control unit 600 corresponds to the drying time calculation means.

The set drying time corresponds to the time required to dry the liquid ink applied in the image formation process for the paper Pn. The set drying time in this embodiment is calculated based on the "printing rate" in the image formation process for the paper Pn. The set drying time is not limited to the printing rate, as long as it is a parameter that can be distinguished as "short," "long," or "medium" by comparison with a predetermined threshold in the process described below. For example, the "set drying time" may be calculated based on the amount of liquid ink used in the image formation process for the paper Pn, or the ratio of the size (area) of the area where the image is formed to the "image formation area" virtually set on the paper Pn.

Next, the calculated "set drying time" is judged to be "short," "medium," or "long" based on a preset "threshold value." Then, based on the judgment result for the set drying time, the transport path (transport route) for the paper Pn is determined.

First, the process branches depending on whether the set drying time of the paper Pn is determined to be "shorter" than a predetermined threshold (S1703). In S1703, if the set drying time of the paper Pn is determined to be "short" (S1703: Y), a check is made to see whether there is a paper P (meaning a paper P as a preceding sheet transported at the previous timing. Hereinafter, it will be referred to as paper Po to distinguish it from paper Pn) already being transported (drying) inside the relay transport device 200 (S1704). If there is no paper Po in the relay transport device 200 (S1704: Y), the transport path of the paper Pn is set to the "straight transport path" as the first transport means, and the paper Pn is guided to the straight transport path (S1705).

In S1704, when it is determined that paper Po is present in the relay transport device 200 (S1704: N), the type of drying time determined for paper Po and the transport path selected for paper Po are determined (S1706). Here, if the set drying time for paper Po is determined to be "short" and the selected transport path is the upper transport path as the second transport means, the transport path for paper Pn is set to the "upper transport path" as the second transport means, and paper Pn is guided to the upper transport path (S1707).

If the two conditions are not met in S1706 (S1706: N), and the type of set drying time determined for paper Po is "short", and the transport path selected for paper Po is a straight transport path as the first transport means (S1708: Y), the transport path for paper Pn is set to the "straight transport path" as the first transport means, and paper Pn is guided to the straight transport path (S1709).

If the two conditions are not met in S1708 (S1708: N), and the type of set drying time determined for paper Po is "short", and the transport path selected for paper Po is the lower transport path as the third transport means, the transport path for paper Pn is set to the "lower transport path" as the third transport means, and paper Pn is guided to the lower transport path (S1711), if the two conditions are met (S1710: Y).

If the two conditions are not met in S1710 (S1710: N), and the type of set drying time determined for paper Po is "medium," and the transport path selected for paper Po as the second transport means is the upper transport path (S1712: Y), the transport path for paper Pn is set to the "straight transport path," and paper Pn is guided to the straight transport path (S1713).

If the two conditions are not met in S1712 (S1712: N), and the set drying time determined for paper Po is "medium," and the transport path selected for paper Po is a straight transport path as the first transport means, the transport path for paper Pn is set to the "upper transport path," and paper Pn is guided to the upper transport path (S1715), if the two conditions are met (S1714: Y).

If the two conditions are not met in S1714 (S1714: N), and the set drying time determined for paper Po is "medium," and the transport path selected for paper Po as the third transport means is the lower transport path (S1716: Y), the transport path for paper Pn is set to the "lower transport path," and paper Pn is guided to the lower transport path (S1717).

If the two conditions are not met in S1716 (S1716: N), and the set drying time determined for paper Po is "long," and the transport path selected for paper Po as the second transport means is the upper transport path (S1718: Y), the transport path for paper Pn is set to the "lower transport path," and paper Pn is guided to the lower transport path (S1719).

If the two conditions are not met in S1718 (S1718: N), and the set drying time determined for paper Po is "long," and the transport path selected for paper Po is a straight transport path as the first transport means, the transport path for paper Pn is set to the "lower transport path," and paper Pn is guided to the lower transport path (S1721), if the two conditions are met (S1720: Y).

If neither of the two conditions are met in S1720 (S1720: N), the transport path for paper Po is set to the "lower transport path" and paper Pn is guided to the lower transport path (S1722).

As described above, the relay transport device 200 determines the transport route for the paper Pn based on the drying time calculated for the paper Pn transported from the printer 100, and also based on the set drying time of the paper Po transported immediately before and the transport path set for the paper Po.

After the transport path for paper Pn has been set, the "set drying time" and "transport path" for paper Pn are stored in RAM 603, which serves as a storage means (S1723).

Return to S1703. In S1703, if the set drying time of the paper Pn is not determined to be "short" (S1703:N), the process branches depending on whether the set drying time of the paper Pn is determined to be "medium" compared to a predetermined threshold value (S1801), as shown in FIG. 15. In S1801, if the set drying time of the paper Pn is determined to be "medium" (1801:Y), a check is made to see if there is a paper Po already being transported (drying) inside the relay transport device 200 (S1802). If there is no paper Po in the relay transport device 200 (S1802:Y), the transport path of the paper Pn is set to the "upper transport path" as the second transport means, and the paper Pn is guided to the upper transport path (S1803).

In S1802, when it is determined that paper Po is present in the relay transport device 200 (S1802: N), the type of set drying time determined for paper Po and the transport path selected for paper Po are determined (S1704). Here, if the set drying time for paper Po is determined to be "short" and the selected transport path is the upper transport path, and the two conditions are met (S1804: Y), the transport path for paper Pn is set to the "upper transport path" and paper Pn is guided to the upper transport path (S1805).

If the two conditions are not met in S1804 (S1804: N), and the type of set drying time determined for paper Po is "short", and the transport path selected for paper Po is a straight transport path, the transport path for paper Pn is set to the "upper transport path", and paper Pn is guided to the upper transport path (S1807), if the two conditions are met (S1806: Y), the transport path for paper Pn is set to the "upper transport path", and paper Pn is guided to the upper transport path (S1807).

If the two conditions are not met in S1806 (S1806: N), and the type of set drying time determined for paper Po is "short," and the transport path selected for paper Po is the lower transport path, the transport path for paper Pn is set to the "lower transport path," and paper Pn is guided to the lower transport path (S1809), if the two conditions are met (S1808: Y), the transport path for paper Pn is set to the "lower transport path," and paper Pn is guided to the lower transport path (S1809).

If the two conditions are not met in S1808 (S1808: N), and the type of set drying time determined for paper Po is "medium," and the transport path selected for paper Po is the upper transport path, the transport path for paper Pn is set to the "upper transport path," and paper Pn is guided to the upper transport path (S1811), if the two conditions are met (S1810: Y).

If the two conditions are not met in S1810 (S1810: N), and the set drying time determined for paper Po is "medium" and the transport path selected for paper Po is a straight transport path (S1812: Y), the transport path for paper Pn is set to the "lower transport path" and paper Pn is guided to the lower transport path (S1813).

If the two conditions are not met in S1812 (S1812: N), and the set drying time determined for paper Po is "medium" and the transport path selected for paper Po is the lower transport path (S1814: Y), the transport path for paper Pn is set to the "lower transport path" and paper Pn is guided to the lower transport path (S1815).

If the two conditions are not met in S1814 (S1814: N), and the set drying time determined for paper Po is "long" and the transport path selected for paper Po is the upper transport path, the transport path for paper Pn is set to the "lower transport path" and paper Pn is guided to the lower transport path (S1817), if the two conditions are met (S1816: Y), the transport path for paper Pn is set to the "lower transport path" and paper Pn is guided to the lower transport path (S1817).

If the two conditions are not met in S1816 (S1816: N), and the set drying time determined for paper Po is "long" and the transport path selected for paper Po is a straight transport path (S1818: Y), the transport path for paper Pn is set to the "lower transport path" and paper Pn is guided to the lower transport path (S1819).

If neither of the two conditions are met in S1818 (S1818: N), the transport path for paper Po is set to the "lower transport path" and paper Pn is guided to the lower transport path (S1820).

After the transport path for paper Pn has been set, the "set drying time" and "transport path" for paper Pn are stored in RAM 603, which serves as a storage means (S1821).

The process returns to S1801. In S1801, if the set drying time of the paper Pn is not determined to be "intermediate" (S1801:N), as shown in FIG. 16, a check is made inside the relay conveying device 200 to see if there is a paper Po already being conveyed (drying) (S1901). If there is no paper Po in the relay conveying device 200 (S1901:Y), the conveying path for the paper Pn is set to the "lower conveying path" and the paper Pn is guided to the lower conveying path (S1902).

In S1901, when it is determined that paper Po is present in the relay transport device 200 (S1901: N), the type of set drying time determined for paper Po and the transport path selected for paper Po are determined (S1903). Here, if the set drying time for paper Po is determined to be "short" and the selected transport path is the upper transport path (S1903: Y), the transport path for paper Pn is set to the "straight transport path" and paper Pn is guided to the straight transport path (S1904).

If the two conditions are not met in S1903 (S1903: N), and the type of set drying time determined for paper Po is "short", and the transport path selected for paper Po is a straight transport path, the transport path for paper Pn is set to the "upper transport path", and paper Pn is guided to the upper transport path (S1906), if the two conditions are met (S1905: Y), the transport path for paper Pn is set to the "upper transport path", and paper Pn is guided to the upper transport path (S1906).

If the two conditions are not met in S1905 (S1905: N), and the type of set drying time determined for paper Po is "short" and the transport path selected for paper Po is the lower transport path, the transport path for paper Pn is set to the "upper transport path" and paper Pn is guided to the upper transport path (S1908), if the two conditions are met (S1907: Y), the transport path for paper Pn is set to the "upper transport path" and paper Pn is guided to the upper transport path (S1908).

If the two conditions are not met in S1907 (S1907: N), and the type of set drying time determined for paper Po is "medium" and the transport path selected for paper Po is the upper transport path (S1909: Y), the transport path for paper Pn is set to the "straight transport path" and paper Pn is guided to the straight transport path (S1910).

In S1909, if the two conditions are not met (S1909: N), the type of set drying time determined for paper Po is "medium" and the transport path selected for paper Po is a straight transport path, if the two conditions are met (S1911: Y), the transport path for paper Pn is set to either the "lower transport path" or the "upper transport path" and paper Pn is guided to the set transport path (S1912). In S1912, the upper transport path is set with priority. In other words, if paper Po is not present in the upper transport path when S1912 is executed (if there is space in the upper transport path to receive paper Pn), paper Pn is guided to the upper transport path.

If the two conditions are not met in S1911 (S1911: N), and the set drying time determined for paper Po is "medium" and the transport path selected for paper Po is the lower transport path (S1913: Y), the transport path for paper Pn is set to either the "lower transport path" or the "upper transport path" and paper Pn is guided to the set transport path (S1914).

In S1914, the transport path for paper Pn is set according to the dryness of paper Po guided to the lower transport path or the upper transport path. For example, if paper Po guided to the upper transport path is dry and can be conveyed to the post-processing device 300, the transport path for paper Pn is set to the "upper transport path" and paper Pn is guided to the upper transport path. Here, the determination of "whether or not dry" is based on the residence time for paper Po calculated in S1702 relative to the set drying time for paper Po, and is based on the residence time from S1702 for paper Po to the execution of S1914 for paper Pn. If the residence time exceeds the set drying time, paper Po is determined to be dry, and if the residence time is less than the set drying time, paper Po is determined to be not dry.

If the two conditions are not met in S1913 (S1913: N), and the set drying time determined for paper Po is "long" and the transport path selected for paper Po is the upper transport path (S1915: Y), the transport path for paper Pn is set to the "straight transport path" and paper Pn is guided to the straight transport path (S1916).

In S1915, if the two conditions are not met (S1915: N), and the set drying time determined for paper Po is "long" and the transport path selected for paper Po is a straight transport path, if the two conditions are met (S1917: Y), the transport path for paper Pn is set to either the "lower transport path" or the "upper transport path", and paper Pn is guided to the set transport path (S1918). In S1918, the upper transport path is set with priority. In other words, if paper Po is not present in the upper transport path when S1918 is executed (if there is space in the upper transport path to receive paper Pn), paper Pn is guided to the upper transport path.

If the two conditions are not met in S1917 (S1917: N), the transport path for paper Pn is set to either the "lower transport path" or the "upper transport path," and paper Pn is guided to the set transport path (S1919). In S1919, the upper transport path is set as a priority. In other words, when S1919 is executed, if paper Po is not present in the upper transport path (if there is space in the upper transport path to receive paper Pn), paper Pn is guided to the upper transport path.

After the transport path for paper Pn has been set, the "set drying time" and "transport path" for paper Pn are stored in RAM 603, which serves as a storage means (S1920).

<Operation Example of Intermediate Conveyance Device 200>
A more detailed example of the operation of the relay conveyance device 200 that determines the conveyance path for the paper Pn and conveys the paper Pn as described above will be described below.

The straight transport path as the first transport means is a transport path that is set when it is determined that the print rate of the paper Pn is low and that an image formation process is being performed to the extent that drying is completed while the paper Pn is being transported toward the post-processing device 300. For example, it is a transport path that is selected for transporting paper Pn (object) that does not require a relatively long time to be set until it is conveyed to the post-processing device 300, by temporarily presenting (putting on hold) the transport of the paper Pn or temporarily slowing down the transport speed, etc.

The upper transport path is used when image formation is performed in a single print job in which paper Pn with a long dimension (length) in the transport direction (transport length > transport width) and paper Pn with a short dimension (length) in the transport direction (transport width > transport length) are mixed (mixed loading). Here, information including the dimensions of paper Pn in the transport direction can be obtained from information included in the "paper information". For example, the upper transport path is also used as a transport path to temporarily evacuate paper Pn with a long dimension in the transport direction when it is transported. The upper transport path is also used to temporarily evacuate paper Pn of the same size when the printing rate is high consecutively (i.e., when a relatively long drying time is required before the paper is transported to the post-processing device 300).

The lower transport path is the transport path used when, in the case of transport using the upper transport path, it is determined that drying will not be completed by the time the paper Pn is transported to the post-processing device 300, taking into account the set drying time calculated based on the printing rate of the paper Pn.

As already explained, the relay transport device 200 is provided with entrance transport rollers 211 that transport paper Pn transported from the printer 100 to the entrance, and an entrance sensor 213 is provided directly below the entrance transport rollers 211 on the downstream transport side. The exit transport rollers 215, which are the transfer section for paper P to the post-processing device 300, are driven by a paper discharge motor 626. An exit sensor 216 is provided on the upstream transport side of the exit transport rollers 215.

The straight transport roller pair 217, which constitutes the straight transport path as the first transport means, is driven by the straight transport motor 621. The straight transport roller pair 217 may be configured with a one-way clutch to increase the transport speed of the paper P to the post-processing device 300 as the downstream device. The straight transport roller pair 217 is optimally positioned to cover the minimum transport length of the paper P, and there is no limit to the number of them.

The upper transport roller pair 219, which constitutes the upper transport path as the second transport means, is driven by the upper transport motor 620. The upper transport roller pair 219 may be configured with a one-way clutch to increase the transport speed of the paper P to the post-processing device 300 as the downstream device. The upper transport roller pair 219 is optimally positioned to cover the minimum transport length of the paper P, and there is no limit to the number of them.

The lower conveying roller pair 222, which constitutes the lower conveying path as the third conveying means, is driven by a lower conveying motor 622. The lower conveying roller pair 222 may also be configured with a one-way clutch to increase the conveying speed to the post-processing device 300 as the downstream device. The lower conveying roller pair 222 is optimally positioned to cover the minimum conveying length of the paper Pn, and there is no limit to the number of them. In addition, multiple lower conveying roller pairs 222 are positioned, and clutches 629 are provided so that the lower conveying roller pairs 222 can be driven individually. The clutches 629 are configured to be switched ON/OFF by the clutch drive unit 619.

The relay conveying device 200 is equipped with multiple sensors that detect the presence or absence of paper P on each conveying path and the conveying state. The detection state by each sensor is notified to the CPU 601 via the I/O 606 and is used for predetermined control.

In addition, paper rotor devices 250 are arranged on the lower transport path directly below the transport branch section 210a and immediately before the transport junction section 210b, as transport direction change means for rotating the orientation of the paper relative to the transport direction. The paper rotor device 250 arranged directly below the transport branch section 210a is driven by an entrance rotate motor 623. The paper rotor device 250 arranged in a straight line at the transport junction section 210b is driven by an exit rotate motor 624.

The effect of placing the paper rotor device 250 will be explained. When the relationship between the "paper transport length, which corresponds to the length dimension of the paper P in the transport direction" and the "dimension in the direction perpendicular to the transport direction of the paper P, which is the so-called width dimension", is "paper transport length > paper width", the number of papers Pn (sheets) that can be held at the same time in the lower transport path is reduced. Therefore, the paper rotor device 250 rotates the paper P (paper Pn) 90 degrees in the transport direction. In other words, the parts that were the ends in the width direction during transport are rotated so that they become the leading and trailing ends. By doing so, the dimensions (lengths) in the transport direction of each piece of paper P held in the lower transport path can be shortened, and the number of papers P that can be held on the transport path can be increased.

At the entrance side (transport branch section 210a), the rotated paper P is rotated back to the transport direction by the paper rotor device 250 just before it reaches the transport junction section 210b, and then is transported to the post-processing device 300.

When the relay transport device 200 having the above configuration accepts paper P from the printer 100, it receives "paper information" about the paper P from the printer 100, obtains the "printing rate" from this paper information, and determines and sets the transport path. As already explained, when the printing rate is low (the drying time is "short" relative to the threshold value), the paper P can be transported using the straight transport path.

Next, we will explain how to set the transport path for each sheet P when the image formation process is continuously performed in a "job," which is a processing unit for executing the image formation process in the printer 100, and multiple sheets P are transported to the relay transport device 200. Note that the sheet P is transported with the transport path length shorter than its width.

Let's assume that a job is being executed and that the job includes paper P with a high printing rate. For example, let's assume that the printing rate of each paper P is different, as follows:

1st page: Low print rate 2nd page: High print rate 3rd page: Low print rate 4th page: Low print rate 5th page: Low print rate 6th page: Low print rate

When the first sheet of paper P is transported from the printer 100, the printing rate of this sheet of paper P is low, so it is guided to the straight transport path. The first sheet of paper P is then discharged to the post-processing device 300 without stopping transport.

Next, when the second sheet of paper P is transported from the printer 100, the print rate of this sheet of paper P is high, so the transport path for the second sheet of paper P is set in relation to the print rates of the subsequent multiple sheets of paper P. As illustrated above, the print rate of the second sheet of paper P is relatively higher than the print rate of the third sheet of paper, so the second sheet of paper P is guided to the upper transport path.

In this case, when the rear end of the second sheet P is transported to a position where it does not catch on the upper transport switching claw 236, the upper transport roller pair 219 is stopped. In this case, the inlet transport roller 211 may also be stopped at the same time.

When the third sheet of paper P is subsequently transported from the printer 100, the print rate of this sheet of paper P is relatively low, so it is guided to the lower transport path. When the third sheet of paper P is transported to a position where the rear end of the sheet of paper P does not catch on the lower transport switching claw 235, the lower transport roller pair 222 is stopped. In this case, the entrance transport roller 211 may also be stopped at the same time.

Next, the fourth, fifth, and sixth sheets of paper P all have relatively low printing rates, so they are all guided to the lower transport path and transported. Then, when the transport guidance for the first six sheets is complete, the transport of the second sheet of paper P, which had been evacuated to the upper transport path, begins, and it is discharged to the post-processing device 300.

The paper P being transported (guided) to the lower transport path stops at the position of the sensor located just before the transport junction 210b, and resumes transport when the rear end of the second sheet of paper P passes the exit sensor 216, and is discharged to the post-processing device 300.

When transport control is being performed for "short size" paper P, whose length in the transport direction is shorter than its width, if "long size" paper P, whose length in the transport direction is longer than its width, is mixed in, the long size paper P is evacuated to the upper transport path, just like the second sheet P with a high print rate described above. Then, the paper P transported by the execution of the same print job is controlled to be discharged to the post-processing device 300 in the order of image formation.

The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the technical gist of the invention. All technical matters included in the technical ideas described in the claims are covered by the present invention. The above-described embodiments are preferred examples, but a person skilled in the art can realize various modifications from the disclosed contents. Such modifications are also included in the technical scope described in the claims.

100: Printer 200: Intermediate conveying device 201: Entrance guide plate 210: Conveying branch section 210a: Conveying branch section 210b: Conveying branch section 210c: Conveying section 210d: Conveying section 210e: Conveying section 210f: Conveying section 211: Entrance conveying roller 211a: Drive roller 213: Entrance sensor 215: Exit conveying roller 216: Exit sensor 217: Straight conveying roller pair 219: Upper conveying roller pair 222: Lower conveying roller pair 230: Spur roller 231: Drive roller 232: Drive roller 233: Drive roller 234: Drive roller 235: Lower conveying switching claw 236: Upper conveying switching claw 237: Guide plate 240: Paper rotor device 241: Drive roller 242: Guide plate 243: Guide plate 244: Guide plate 300 : post-processing device 600 : control unit 601 : CPU
602: ROM
603: RAM
604: Upstream machine I/F
605: Peripheral device I/F
606: I/O
610: Motor drive unit 611: Motor drive unit 612: Motor drive unit 613: Motor drive unit 614: Motor drive unit 615: Motor drive unit 616: Motor drive unit 617: Motor drive unit 618: Motor drive unit 619: Clutch drive unit 620: Upper transport motor 621: Straight transport motor 622: Lower transport motor 623: Inlet rotate motor 624: Outlet rotate motor 626: Paper discharge motor 627: First inlet branch motor 628: Second inlet branch motor 629: Clutches 1000: Print system P: Paper Pn: Paper Po: Paper

JP 2008-214020 A

Claims (6)

A sheet conveying device that includes a plurality of conveying paths arranged in parallel and conveys a conveyed sheet from an upstream side in a conveying direction to a downstream side in the conveying direction,
a drying time calculation unit that calculates a drying time of the sheet based on sheet-related information related to the conveyed sheet;
a conveying path selection means for selecting one of the plurality of conveying paths as a conveying path for conveying the sheet;
a sheet guide means for guiding the sheet to the selected conveying path,
2. The sheet transport device according to claim 1, wherein the transport path selection means selects the transport path based on a drying time of the sheet. The sheet conveying device according to claim 1, further comprising a conveying direction changing means for rotating the sheet relative to the conveying path to change the conveying direction when the sheet has a width dimension shorter than its length dimension in the conveying direction in at least one conveying path. The sheet conveying device according to claim 1 or 2, wherein the sheet-related information includes at least one of information indicating the size of the sheet and a printing rate related to the sheet. a conveying unit capable of conveying or stopping the conveyance of the sheet,
4. The sheet transporting device according to claim 1, further comprising: a control unit that controls the transport unit of the transport path selected by the transport path selection unit. The sheet conveying device according to claim 4, wherein the conveying means is capable of conveying the sheet in units of the conveying length of the sheet. an image forming apparatus that forms an image on a sheet and conveys the sheet;
a post-processing device for performing post-processing on the sheet on which the image is formed;
6. An image forming system comprising: the sheet conveying device according to claim 1, which conveys a sheet conveyed from the image forming device to the post-processing device.