JP2021084731A - Image formation apparatus, sheet conveyance apparatus and conveyance interval adjustment method - Google Patents

Abstract

To provide an image formation apparatus, sheet conveyance apparatus and conveyance interval adjustment method which can stabilize the loading state of sheets on a sheet tray while suppressing reduction in the conveyance efficiency of the sheets.SOLUTION: A control unit 100 of a compound machine 1 determines the discharge number of print sheets discharged to trays 36A, 36B, estimates whether or not the print sheets to be printed are easily curled after the image formation processing by an image formation unit 18, and controls the conveyance of the print sheets by each of a sheet conveyance unit 15 of an image formation apparatus 10 and a sheet discharge unit 70 of a sheet processing apparatus 30 such that the conveyance interval of the respective print sheets continuously conveyed by the sheet discharge unit 70 are longer than the current interval when it is determined that the print sheets are easily curled and it is determined that the loading amount is equal to or greater than a prescribed threshold.SELECTED DRAWING: Figure 5

Description

The present invention relates to an image forming apparatus and a sheet conveying apparatus including a sheet discharging portion for discharging a sheet after an image forming process, and a method for adjusting a conveying interval.

In an image forming apparatus that forms an image on a sheet, the sheet after the image forming process may be curled. This curl causes a poor loading of the seat in the seat tray.

Conventionally, there is known a paper ejection device capable of decelerating the ejection speed of printing paper after image formation to stabilize the ejection state of printing paper (see Patent Document 1). This paper ejection device reduces the ejection speed when the type of printing paper is relatively thick thick paper such as postcards and business cards.

JP-A-2002-274726

However, in the conventional paper ejection device described above, the ejection speed is uniformly reduced with respect to the thick paper, so when the image is formed on the thick paper, the number of ejected sheets of the thick paper after the image formation per unit time is lower than usual. As a result, the transport efficiency is significantly deteriorated.

An object of the present invention is to provide an image forming apparatus, a sheet conveying device, and a conveying interval adjusting method capable of stabilizing a loading state of sheets in a sheet tray while suppressing a decrease in sheet conveying efficiency. is there.

The image processing apparatus according to one aspect of the present invention includes an image forming unit, a sheet discharging unit, a load amount determining unit, a curl estimation unit, and a transport control unit. The image forming unit performs an image forming process on the sheet. The sheet discharging unit conveys the sheet after the image forming process by the image forming unit and discharges it to a predetermined sheet tray. The load capacity determination unit determines the load capacity of the sheets discharged to the seat tray. The curl estimation unit estimates whether or not the sheet is a sheet that is easily curled after the image forming process. When the transfer control unit determines that the sheet is easily curled by the curl estimation unit and the load amount determination unit determines that the load amount is equal to or higher than a predetermined threshold value, the sheet discharge unit continuously conveys the sheet. Increase the transport interval of each sheet to be processed.

The sheet transfer device according to another aspect of the present invention includes a sheet discharge unit, a load capacity determination unit, a curl estimation unit, and a transfer control unit. The sheet discharging unit conveys the sheet after the image forming process and discharges it to a predetermined sheet tray. The load capacity determination unit determines the load capacity of the sheets discharged to the seat tray. The curl estimation unit estimates whether or not the sheet is a sheet that is easily curled after the image forming process. When the transfer control unit determines that the sheet is easily curled by the curl estimation unit and the load amount determination unit determines that the load amount is equal to or higher than a predetermined threshold value, the sheet discharge unit continuously conveys the sheet. Increase the transport interval of each sheet to be processed.

The transfer interval adjusting method according to another aspect of the present invention is a method of adjusting the transfer interval of sheets applied to the sheet transfer device, which includes a load capacity determination step, a curl estimation step, a transfer interval change step, and a transfer interval change step. Has. The load capacity determination step performs a process of determining the load capacity of the sheets discharged to a predetermined seat tray after the image formation process. The curl estimation step performs a process of estimating whether or not the sheet is a sheet that is easily curled after the image forming process. The transfer interval changing step is continuously performed in the sheet transfer device when the sheet is determined to be easily curled by the curl estimation step and the load amount is determined to be equal to or higher than a predetermined threshold value by the load amount determination step. A process of changing so that the transport interval of each sheet to be transported becomes longer is performed.

According to the present invention, it is possible to stabilize the loading state of the sheets in the sheet tray while suppressing the decrease in the sheet transporting efficiency.

FIG. 1 is a diagram showing a configuration of a sheet processing device according to an embodiment of the present invention and an image forming device to which the sheet processing device is connected. FIG. 2 is a cross-sectional view showing the internal configuration of the image forming apparatus of FIG. FIG. 3 is a cross-sectional view showing the internal configuration of the sheet processing apparatus of FIG. FIG. 4 is a block diagram showing the configurations of the sheet processing apparatus and the image forming apparatus of FIG. FIG. 5 is a flowchart showing an example of a procedure of sheet transport control processing executed by the control unit of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. It should be noted that the embodiments described below are merely examples that embody the present invention, and do not limit the technical scope of the present invention.

As shown in FIG. 1, the multifunction device 1 (an example of the image forming apparatus of the present invention) according to the embodiment of the present invention includes a sheet processing apparatus 30 and an image forming apparatus 10, and the image forming apparatus 10 to the sheet. The sheet processing device 30 is connected to the image forming device 10 so that the printing paper after the image formation can be conveyed to the processing device 30.

[Image forming apparatus 10]
The image forming apparatus 10 includes various functions such as a printer, a copying machine, and a facsimile. As shown in FIG. 1, the sheet processing device 30 is connected to the left side surface 14A of the image forming device 10. The image forming apparatus 10 prints an image based on the input image data on printing paper using a printing material such as toner. The image forming apparatus 10 is not limited to the one having a plurality of functions, and may have a single function such as a printer, a facsimile, or a copying machine.

The image forming apparatus 10 forms an image on printing paper based on image data input from the outside via a network communication unit (not shown) and image data read by a scanner 11 arranged above the image forming apparatus 10. To print. As shown in FIG. 2, the image forming apparatus 10 mainly includes a scanner 11, an operation display panel 12, and an image forming unit 18 that performs a process of forming an image on a sheet (image forming process) based on an electrophotographic method. , A fixing unit 19, a discharge sheet holding unit 21, a sheet transporting unit 15, a paper feed tray 16 (161 to 164), and a storage unit 17. Further, the sheet transport unit 15 includes a paper feed unit 151, a plurality of transport roller pairs 152, and a discharge roller pair 153. Further, the image forming apparatus 10 includes a control unit 100 (see FIG. 4) that collectively controls the multifunction device 1 including the sheet processing apparatus 30. These elements are provided inside the cover of the outer frame of the image forming apparatus 10 and the housing 14 constituting the inner frame.

As shown in FIG. 2, the image forming apparatus 10 is provided with a plurality of paper feed trays 16 (161 to 164). In each paper feed tray 16, printing papers of different sizes and paper types are stored in a stack. For example, the uppermost (first stage) paper feed tray 161 accommodates A4 size so-called plain paper (printing paper having a thickness of about 0.08 mm). B4 size plain paper is stored in the second-stage paper feed tray 162. A3 size plain paper is stored in the third-stage paper feed tray 163. A4 size special paper is stored in the lowermost (fourth) paper feed tray 164. The special paper is, for example, glossy paper, coated paper, high-quality paper, etc., which are thicker than the plain paper. Information about the printing paper (paper type, size, etc.) stored in each paper feed tray 16 is stored in the storage unit 17 of the image forming apparatus 10 in association with each paper feed tray 16. In the present embodiment, for example, when the user copies the original or prints out the original data, the operation display panel 12 or the printer driver specifies (selects) the paper feed tray 16 in which the paper to be printed is stored. Then, information about the printing paper stored in the paper feed tray 16 is input to the control unit 100 (conveyance control unit 106).

Four paper feed units 151 are provided inside the housing 14 corresponding to the plurality of paper feed trays 16. Four paper feed units 151 are arranged in the vertical direction. When image formation is performed on a plurality of sheets of printing paper, the paper feed unit 151 picks up the printing papers stored in the paper feed tray 16 one by one at predetermined reference intervals and sequentially moves them to the image forming unit 18. Send it. The printing paper fed to the image forming unit 18 by the feeding unit 151 is conveyed to the fixing unit 19 after the toner image is transferred to the surface by the image forming unit 18. Since the image forming unit 18 is a well-known mechanism having an LSU, a photoconductor drum, a developing unit, a charging unit, a transfer unit, and the like, detailed description thereof will be omitted here.

The fixing unit 19 has a heating unit such as an IH heater, and fixes the toner image transferred to the printing paper to the printing paper by heat. In the process of the printing paper passing through the fixing portion 19, heat is supplied from the fixing portion 19 to melt the toner. As a result, the toner image is fixed on the printing paper, and the image is fixed on the printing paper. The printing paper on which the image is fixed by the fixing unit 19 is sent out to the transport path 28 formed on the downstream side of the fixing portion 19 in the transport direction of the printing paper. The printing paper sent out to the transport path 28 is further transported to the downstream side in the transport direction of the printing paper by a plurality of transport roller pairs 152 provided along the transport path 28.

In the present embodiment, an image forming apparatus 10 including an image forming unit 18 for forming an image on printing paper based on an electrophotographic method is illustrated, but the image forming unit 18 prints based on, for example, an inkjet recording method. It may form an image on paper. In this case, the fixing portion 19 is unnecessary, and it is preferable that the fixing portion 19 is provided with a drying portion for drying the ink adhering to the sheet.

The transport path 28 extends horizontally in the housing 14 up to the fixing portion 19, is curved upward from the downstream side of the fixing portion 19, and extends straight upward vertically. On the downstream side of the fixing portion 19, the transport path 28 is branched into two. One branch path 28A of the transport path 28 reaches the paper discharge port 22, and the other branch path 28B reaches the transport relay port 27 formed on the left side surface 14A of the housing 14. Further, at the branch point between the branch path 28A and the branch path 28B, a flap 25 that is swung by a drive unit (not shown) such as a motor or a solenoid is provided.

When the printing paper is discharged to the discharge sheet holding portion 21 provided on the upper part of the image forming apparatus 10, the flap 25 closes the branch path 28B and is arranged at a paper discharge position where the printing paper can be guided to the branch path 28A. Will be done. When the flap 25 is in the paper ejection position, the printing paper after image formation is ejected to the ejection sheet holding portion 21 by the transport roller pair 152. Further, when the printing paper is conveyed to the sheet processing apparatus 30, the flap 25 is arranged at a relay position (position shown in FIG. 2) that closes the branch path 28A and can guide the printing paper to the branch path 28B. As shown in FIG. 2, the branch path 28B is provided with a discharge roller pair 153 that conveys the printing paper after image formation to the sheet processing device 30. The discharge roller pair 153 is composed of a drive roller that is rotationally driven by a motor or the like, and a driven roller that is driven in a state of being pressed against the drive roller. Therefore, when the flap 25 is in the relay position, the printing paper after image formation is conveyed to the sheet processing device 30 by the discharge roller pair 153.

The operation display panel 12 is provided on the upper right side of the front surface of the image forming apparatus 10. The operation display panel 12 has a touch panel type liquid crystal display unit, and hard keys such as a numeric keypad, a function selection key, and a start key. In addition, the liquid crystal display unit displays setting keys and buttons used for setting the size of printing paper used for printing, image enlargement / reduction, print density, and the like. In addition, the liquid crystal display unit is used for setting keys used for setting various printing conditions such as whether or not staple processing is executed and the destination of printed printing paper (upper tray 36A or lower tray 36B) is selected. Display the button.

[Sheet processing device 30]
The sheet processing device 30 is a device that performs post-processing such as stapling processing and punching processing (punching processing) on the printing paper conveyed from the image forming apparatus 10. As shown in FIG. 1, the sheet processing device 30 is used in connection with the image forming device 10. The sheet processing device 30 is not limited to the one that performs the post-processing on the printing paper conveyed from the image forming device 10. For example, when the sheet processing device 30 includes a transport device capable of transporting the printing paper set in an external tray (not shown) to a position where the post-processing is performed, the sheet processing device 30 is transported by the transport device. The paper may be subjected to the post-treatment.

As shown in FIGS. 1 and 3, the sheet processing device 30 includes an upper main body 31 that constitutes the upper side of the housing of the sheet processing device 30, and a lower main body 32 that constitutes the lower side of the housing. In the present embodiment, the upper main body 31 is provided with each unit for post-processing.

The sheet processing device 30 includes a drilling unit 33, a storage container 110, a staple unit 35, a sheet discharging unit 70 (an example of the sheet discharging unit of the present invention), and an upper tray 36A (an example of the sheet tray of the present invention). A lower tray 36B (an example of a sheet tray of the present invention), a stack tray 57, and a sheet matching portion 60 (see FIG. 4) are provided. Further, the sheet discharging unit 70 includes a transport roller pair 37, a discharge roller pair 38, 39, and a transport roller pair 40. These elements are provided inside the upper body 31.

The upper main body 31 has a carry-in entrance 46 on a connecting surface 44 (right side surface in FIG. 3) with the image forming apparatus 10. The carry-in entrance 46 is an entrance for receiving the image-forming printed paper conveyed from the image forming apparatus 10. A discharge port 47 for discharging printing paper from the sheet processing device 30 to the outside is provided in the upper part of the upper main body 31. The upper tray 36A is provided so as to be continuous with the discharge port 47. Further, a discharge port 48 for discharging printing paper from the sheet processing device 30 to the outside is provided on the side surface 45 (left side in FIG. 3) of the upper main body 31. A lower tray 36B is provided so as to be continuous with the discharge port 48. The upper tray 36A and the lower tray 36B hold a plurality of sheets of printing paper discharged from the sheet processing device 30 in a vertically stacked state (laminated state).

A transport path 50 is provided inside the upper main body 31. The transport path 50 extends inward from the carry-in entrance 46 inside the upper main body 31. The printing paper carried into the transport path 50 from the carry-in entrance 46 is guided in the transport direction toward the inside of the upper main body 31 by passing through the transport path 50.

The transport path for printing paper is branched into a transport path 51 from the end of the transport path 50 toward the upper surface of the upper main body 31 and a transport path 52 toward the side surface 45. The transport path 51 reaches the discharge port 47, and the transport path 52 reaches the discharge port 48 via the staple unit 35.

The sheet ejection unit 70 conveys the image-processed printing paper conveyed from the image forming apparatus 10 to the carry-in inlet 46 and ejects it to either the upper tray 36A or the lower tray 36B.

The transport roller pair 37 is provided at an end portion of the transport path 50 on the downstream side in the transport direction. The transport roller pair 37 is composed of a drive roller and a driven roller, and transports the printing paper conveyed from the image forming apparatus 10 further to the downstream side.

The discharge roller pair 39 is provided in the vicinity of the discharge port 47 at the end of the transport path 52. The discharge roller pair 39 is composed of a drive roller 39A and a driven roller 39B, and discharges the printing paper conveyed to the transfer path 51 from the discharge port 47. The drive roller 39A rotates by transmitting a rotational driving force from a drive source such as a motor (not shown). By rotating the drive roller 39A in a state where the driven roller 39B is in contact with the drive roller 39A, the printing paper can be ejected by the ejection roller pair 39.

The discharge roller pair 38 is provided in the vicinity of the discharge port 48 at the end of the transport path 51. The discharge roller pair 38 is composed of a drive roller 38A and a driven roller 38B, and discharges the printing paper conveyed to the transfer path 52 from the discharge port 48. The drive roller 38A rotates by transmitting a rotational driving force from a drive source such as a motor (not shown). The driven roller 38B is arranged above the driving roller 38A and is in contact with the driving roller 38A. Therefore, the driven roller 38B is rotated by rotating the driving roller 38A. By rotating the drive roller 38A in a state where the driven roller 38B is in contact with the drive roller 38A, the printing paper can be ejected by the ejection roller pair 38.

The driven roller 38B is movably supported in a direction in which the driven roller 38B is brought into contact with and separated from the driving roller 38A. The driven roller 38B is configured to be separated upward from a position in contact with the driving roller 38A by a driving mechanism (not shown) such as a solenoid.

The drilling unit 33 is provided in the vicinity of the carry-in inlet 46. The perforation unit 33 performs a predetermined post-processing on the printing paper carried into the transport path 50 from the image forming apparatus 10. Specifically, the perforation unit 33 performs a perforation process on the printing paper conveyed to the transfer path 50. When the printing paper is transported to a predetermined position on the transport path 50, the transport is temporarily stopped, and the perforation unit 33 forms a hole at the tip end portion (end portion on the downstream side in the transport direction) of the printing paper. The perforated residue generated by the perforation process by the perforation unit 33 is housed in the storage container 110 provided below the perforation unit 33.

When the multifunction device 1 is set not to perform the punching process, the printing paper passes through the punching unit 33 without performing the punching process. On the other hand, when the perforation process is set to be executed, the printing paper is conveyed to the downstream side after the perforation process is performed by the perforation unit 33.

A flap 55 is provided at a branch point between the transport path 51 and the transport path 52. The flap 55 is swung by a driving means (not shown) such as a motor or a solenoid, so that the printing paper discharge path is determined. By swinging the flap 55 to an appropriate position, the printing paper is conveyed to a predetermined reaching position.

A transport roller pair 40 is provided in each of the transport paths 51 and 52. The printing paper in the transport paths 51 and 52 is transported to the downstream side in the transport direction of the printing paper by the transport roller pair 40.

As shown in FIG. 3, the stack tray 57 is provided on the downstream side of the punching unit 33 in the transport direction of the printing paper. The stack tray 57 is provided below the transport path 52. One end (left end in FIG. 3) of the stack tray 57 is located at the discharge port 48. Further, the stack tray 57 extends in a direction of obliquely downward inclination when viewed from the discharge port 48. A staple unit 35 is provided at the end of the extension direction. Therefore, the support surface 58 of the stack tray 57 is inclined obliquely downward toward the staple unit 35.

The stack tray 57 constitutes the lower guide surface of the transport path 52 on the downstream side of the transport roller vs. 40 when the staple treatment is not performed. On the other hand, when the staple processing is performed, the stack tray 57 plays a role of supporting a plurality of printing papers to be stapled. In this case, the stack tray 57 sequentially supports the printing paper conveyed through the transport path 52, and can support a plurality of printing papers by loading them in a bundle.

The staple unit 35 performs a staple process on the printing paper. The staple unit 35 automatically staples the printing paper conveyed from the image forming apparatus 10 and loaded on the stack tray 57.

When the multifunction device 1 is set not to perform the staple processing, the printing paper conveyed by the transfer roller pair 40 moves toward the discharge port 48 while being in contact with the support surface 58 of the stack tray 57 and being guided. .. After that, the printing paper is discharged to the lower tray 36B by the discharge roller pair 38 provided in the vicinity of the discharge port 48.

On the other hand, when the multifunction device 1 is set to execute the staple processing, the driving roller 38A and the driven roller 38B are separated from each other. In this state, when the printing paper is conveyed toward the discharge port 48 by the transport roller pair 40, the printing paper moves toward the discharge port 48 along the support surface 58 of the stack tray 57. Since the driving roller 38A and the driven roller 38B are separated from each other, even if the printing paper reaches the discharge roller pair 38, the printing paper is not conveyed by the discharge roller pair 38. Then, when the rear end portion (the end portion on the upstream side in the transport direction) of the printing paper passes through the transport roller pair 40, the printing paper descends to the stack tray 57 side and is supported by the support surface 58. As described above, since the support surface 58 is inclined, when the printing paper is supported by the stack tray 57, the supported printing paper moves to the staple unit 35 side. Specifically, the printing paper slides diagonally downward along the support surface 58 due to its own weight. Then, when the rear end of the printing paper reaches the stopper (not shown) at the lowermost end of the stack tray 57, the printing paper stops at a position (stop position) in contact with the stopper. By repeating this operation, a plurality of printing sheets are supported at the stop position on the stack tray 57.

The sheet matching unit 60 (see FIG. 4) performs a matching process on the printing paper discharged from the discharge port 47 and the discharge port 48. Specifically, the sheet matching unit 60 regulates the discharge direction of the sheets discharged from the discharge port 47 and the discharge port 48, and aligns the rear ends of the printing paper loaded on the upper tray 36A and the lower tray 36B. Then, a matching operation is performed to align the bundles of printing paper loaded on each tray.

The sheet matching portion 60 has a matching member 61 provided in the vicinity of the discharge port 47 and a matching member 62 provided in the vicinity of the discharge port 48. The matching members 61 and 62 are paddle-shaped members (rotary paddle members) that rotate by receiving a rotational driving force from a drive source such as a motor. The matching member 61 is provided below the discharge port 47 and the discharge roller pair 39, and the matching member 62 is provided below the discharge port 48 and the discharge roller pair 38. By rotating the matching members 61 and 62, the rear ends of the printing paper loaded on the sheet mounting surfaces of the corresponding trays 36A and 36B are pressed from above to align the trays 36A and 36A, respectively. Align the bundle of printing paper loaded on 36B. By being rotationally driven, these matching members 61 and 62 come into contact with the uppermost surface of the printing paper loaded on the trays 36A and 36B, and play a role of pulling the uppermost printing paper toward the front. ..

The matching members 61 and 62 are driven and controlled by the control unit 100, so that each time the printing paper is ejected, the matching members 61 and 62 are retracted to an initial position defined inside the upper main body 31 and stand by at the initial position. Then, when the printing paper is discharged from the discharge ports 47 and 48, the matching members 61 and 62 are rotationally driven to rotate from the initial position toward the trays 36A and 36B, and the rear end portion of the printing paper. Align the printing paper by contacting with.

The sheet matching portion 60 has a pair of side guides that come into contact with both ends of the printing paper discharged from the ejection ports 47 and 48 in the width direction to regulate the ejection position of the printing paper in the width direction. You may. The side guide is supported so as to be movable in the width direction, and can be moved in the width direction by receiving a driving force from a drive source such as a motor. In this configuration, the control unit 100 moves the side guides to a position where the distance between the side guides is larger than the width size of the printing paper each time the printing paper is ejected, and the printing paper is discharged from the ejection ports 47 and 48. When ejected, the side guide is moved to a position where the printing paper can be aligned.

By the way, in the conventional paper ejection device, the ejection speed is uniformly reduced with respect to the thick paper, so when the image is formed on the thick paper, the number of ejected sheets of the thick paper after the image formation per unit time is lower than usual. Therefore, the transport efficiency is significantly deteriorated. On the other hand, in the present embodiment, the control unit 100 executes the sheet transport control process described later. Therefore, it is possible to stabilize the loading state of the printing paper in the trays 36A and 36B while suppressing the decrease in the transport efficiency of the printing paper.

[Structure of control unit 100]
The configuration of the control unit 100 and the processing executed by the control unit 100 will be described with reference to FIG. The control unit 100 controls the multifunction device 1 in an integrated manner, and as shown in FIG. 4, the control unit 100 includes control devices such as a CPU 101, a ROM 102, and a RAM 103. The CPU 101 is a processor that executes various arithmetic processes. The ROM 102 is a non-volatile storage medium in which a control program for causing the CPU 101 to execute various arithmetic processes is stored. The RAM 103 is a volatile or non-volatile storage medium that stores various types of information. The control unit 100 may be realized by an IC such as an ASIC.

The control unit 100 can communicate with and control each of the storage unit 17, the operation display panel 12, the scanner 11, the image forming unit 18 (an example of the image forming unit of the present invention), and the sheet conveying unit 15 included in the image forming apparatus 10. It is connected. Further, the control unit 100 can communicate with each of the sheet discharging unit 70, the perforation unit 33, the staple unit 35, and the sheet matching unit 60 included in the sheet processing device 30 in a state where the sheet processing device 30 is connected to the image forming device 10. And it is connected in a controllable manner.

The storage unit 17 is a non-volatile storage medium or storage device such as an HDD, SSD, or flash memory that stores various types of information. The storage unit 17 stores a control program for causing the control unit 100 to execute the sheet transport control process and various arithmetic processes described later, data used for the sheet transfer control process and various arithmetic processes, and the like.

Specifically, information about the printing paper (paper type, size, etc.) stored in each paper feed tray 16 is stored in the storage unit 17 in association with each paper feed tray 16.

Further, the storage unit 17 stores a level value indicating the ease of curling and a threshold value determined according to the level value according to each printing paper. The threshold value is used in the sheet transport control process (determination process in step S14) described later. Generally, the thinner the thickness, the easier it is to curl, and the larger the size, the easier it is to curl. Therefore, regarding the printing paper housed in each paper feed tray 16 of the present embodiment, the A3 size plain paper housed in the paper feed tray 163 is the most easily curled paper, and its level value is level A. It is stipulated in. Further, the B4 size plain paper housed in the paper feed tray 162 is the next most easily curled paper, and its level value is set to level B (<level A). Further, the A4 size plain paper housed in the paper feed tray 161 is the next most easily curled paper, and its level value is set to level C (<level B). Each of these level values and the threshold value corresponding to each level value are stored in the storage unit 17. Here, the threshold value corresponding to the level A is the smallest numerical value, and the threshold value corresponding to the level C is the largest numerical value.

As shown in FIG. 4, the control unit 100 includes a load capacity determination unit 104 (an example of a load capacity determination unit of the present invention), a curl estimation unit 105 (an example of a curl estimation unit of the present invention), and a transfer control unit 106 (this invention). It includes various processing units such as the transport control unit of the present invention). The control unit 100 functions as the various processing units by the CPU 101 executing various arithmetic processes according to the control program. The control unit 100 or the CPU 101 is an example of a computer that executes the control program. A part or all of the processing units included in the control unit 100 may be composed of an electronic circuit or an IC.

The load capacity determination unit 104 determines the load capacity (specifically, the number of sheets to be loaded) of the printing paper loaded on the upper tray 36A or the lower tray 36B in which the printing paper after the image forming process is discharged and held (specifically, the number of loaded sheets). Judgment processing) is performed. For example, when a sheet sensor for counting the number of sheets of printing paper ejected is provided in the vicinity of the ejection ports 47 and 48, the load capacity determination unit 104 is based on the count value based on the output signal of the sheet sensor. , The load capacity of the printing paper in the upper tray 36A or the lower tray 36B is determined. Alternatively, the load capacity determination unit 104 is loaded based on the count values based on the output signals of the sheet sensors provided in the transport paths 28 of the image forming apparatus 10 and the transport paths 50, 51, 52 of the sheet processing device 30. It is also possible to determine the amount. Further, the load capacity determination unit 104 measures the weight of the printed paper loaded based on the output signal of the weight sensor provided on the upper tray 36A or the lower tray 36B, and the measured value and the type information of the printing paper ( For example, it is also possible to determine the load capacity based on (for example, the weight per sheet).

The curl estimation unit 105 performs a process of estimating whether or not the printing paper supplied to the image forming unit 18 by the image forming apparatus 10 is a printing paper that is easily curled. In other words, the curl estimation unit 105 estimates whether or not the printing paper after the image forming process is likely to be curled.

In the present embodiment, the curl estimation unit 105 estimates whether or not the printing paper is easily curled based on the information (type and size of the printing paper) on the printing paper on which the image is formed. When the paper feed tray 16 is designated (selected) when the image forming process is performed, the information related to the printing paper is curled by reading the information corresponding to the designated paper feed tray 16 from the storage unit 17. It is used for the estimation process by the estimation unit 105.

In the present embodiment, an example in which the curl estimation unit 105 estimates whether or not the printing paper is likely to be curled based on the information about the printing paper will be described. Not limited to processing examples. For example, the curl estimation unit 105 further takes into account not only the information about the printing paper but also the printing rate of the image formed on the printing paper and the temperature and humidity information of the space where the multifunction device 1 is installed. It may be used to estimate whether or not the printing paper is easily curled. Further, the curl estimation unit 105 estimates whether or not the printing paper is easily curled based on any one or more of the information about the printing paper, the printing rate, and the temperature and humidity. There may be.

Here, the print rate is calculated by the control unit 100 based on the image data input at the time of image formation. Alternatively, when a density sensor for detecting the density distribution on the paper surface after image formation is provided, the control unit 100 may calculate the print rate based on the output signal from the density sensor. Further, regarding the air temperature and the temperature, the control unit 100 acquires the air temperature and the humidity based on the output signals of the temperature sensor and the humidity sensor provided in the image forming apparatus 10. The print rate, air temperature, and humidity thus acquired may be used for the estimation process by the curl estimation unit 105.

The transfer control unit 106 controls the transfer of printing paper by the sheet transfer unit 15 of the image forming apparatus 10 and the sheet discharge unit 70 of the sheet processing device 30. Further, in the transport control unit 106, it is estimated by the curl estimation unit 105 that the printing paper is easily curled, and the load capacity determination unit 104 determines the load capacity of the printing paper in the upper tray 36A or the lower stage and Example 36B. When it is determined that the threshold value is equal to or higher than the threshold value, a process is performed in which the ejection interval of each printing paper continuously conveyed by the sheet ejection unit 70 is changed to be longer than the current interval.

Specifically, the transfer control unit 106 drives and controls each of the sheet transfer unit 15 of the image forming apparatus 10 and the sheet discharge unit 70 of the sheet processing device 30, and the printing paper by the sheet transfer unit 15 and the sheet discharge unit 70. Control the transport of. As a result, the printing paper is conveyed along each transfer path. Then, the transfer control unit 106 is presumed that the printing paper is likely to curl during the transfer of the printing paper by the sheet discharging unit 70, and the load capacity of the printing paper in the upper tray 36A or the lower stage and Example 36B is increased. When it is determined that the threshold value is equal to or higher than a predetermined threshold value, the transfer interval of the printing paper continuously conveyed by the sheet transfer unit 15 and the sheet discharge unit 70 is made longer than the current interval. For example, the transfer control unit 106 reduces the transfer speed of the printing paper or delays the pick-up timing (feeding timing) of the printing paper by the paper feed unit 151 to make the transfer interval of the printing paper different from the current interval. Is also lengthened.

[Sheet transfer control process]
Hereinafter, an example of the procedure of the sheet transfer control process executed by the control unit 100 will be described with reference to FIG. 5, and the transfer interval adjusting method of the present invention will be described. In the flowchart of FIG. 5, steps S11, S12, ... Represent the processing procedure (step) number. It should be noted that this sheet transport control process will be described as being performed when a print process (continuous print process) accompanied by printing output of a plurality of sheets is executed on the multifunction device 1.

When a print instruction is input to the multifunction device 1, the control unit 100 determines whether or not the print instruction is a continuous print instruction for printing a plurality of sheets (S11). For example, when the print job data including the document data to be printed is input from the external device connected to the network, the control unit 100 determines that the print instruction has been input, and print data of a plurality of pages in the print job data. Is included, or when information indicating that the number of copies is printed is included, it is determined that the continuous printing instruction has been input. After that, the control unit 100 performs the process of step S12.

In step S12, the control unit 100 determines whether or not the printing paper printed by the continuous printing instruction is easily curled. Generally, the thinner the thickness, the easier it is to curl, and the larger the size, the easier it is to curl. Therefore, in the present embodiment, in the continuous printing instruction, the uppermost stage and the second stage containing plain paper having a thickness of about 0.08 mm are accommodated. When any of the eyes and the third-stage paper feed trays 161, 162, and 163 is specified, it is determined that the printing paper to be printed is easily curled. Further, in general, the thicker the thickness, the more difficult it is to curl. Therefore, in the present embodiment, when the lowermost paper feed tray 164 containing special paper having a thickness thicker than that of the plain paper is specified in the continuous printing instruction. Is determined that the printing paper to be printed is hard to curl. Note that step S12 is an example of the curl estimation step of the present invention.

If it is determined in step S12 that the paper is difficult to curl, a series of processes is completed without lengthening the transfer interval of the transferred printing paper. On the other hand, if it is determined in step S12 that the paper is easily curled, the process proceeds to step S13.

In the next step S13, the level value corresponding to the paper feed tray 16 specified in the continuous printing instruction is acquired from the storage unit 17, and the threshold value corresponding to the level value is read out from the storage unit 17.

In step S14, the control unit 100 determines whether or not the total number of prints of the print output based on the continuous printing instruction is equal to or greater than the threshold value read in step S13. Here, the threshold value is the maximum number of sheets that can maintain a stable loading state even if the printing paper is curled when the printing paper after image formation is ejected to the upper tray 36A or the lower tray 36B which is the ejection destination. Is set to. For example, 50 sheets of A4 size plain paper, 40 sheets of B4 size plain paper, and 30 sheets of A3 size plain paper are set.

If it is determined in step S14 that the total number of prints is less than the threshold value, it is not necessary to lengthen the transfer interval of the transferred printing papers, so that a series of processes is completed. On the other hand, if it is determined in step S14 that the total number of prints is equal to or greater than the threshold value, the process proceeds to step S15.

In step S15, the control unit 100 determines whether or not the number of printed papers (output sheets) discharged to the upper tray 36A or the lower tray 36B has reached the threshold value. As described above, the control unit 100 is, for example, a sheet sensor provided in the vicinity of the discharge ports 47, 48, or the transfer paths 28 of the image forming apparatus 10 and the transfer paths 50, 51, 52 of the sheet processing device 30. It is possible to make the determination in step S15 based on the count value based on the output signal of the seat sensor provided in. Note that step S15 is an example of the load capacity determination step of the present invention.

When it is determined in step S15 that the number of sheets to be ejected has reached the threshold value, the control unit 100 increases the transport interval of the continuously conveyed printing paper to be longer than the current interval (S16). That is, the control unit 100 controls the transfer of printing paper by the sheet transfer unit 15 of the image forming apparatus 10 and the sheet discharge unit 70 of the sheet processing device 30 so that the transfer interval becomes longer than the current interval. .. For example, the control unit 100 uses the timing of picking up the printing paper by the paper feed unit 151 as the reference while maintaining the transfer speeds of the plurality of transfer rollers 152, the discharge roller pair 153, and the sheet discharge unit 70 at the current transfer speeds. Make it longer than the interval. As a result, the transfer interval (that is, the distance interval) of each printing paper continuously conveyed by the plurality of transfer roller pairs 152, the discharge roller pair 153, and the sheet discharge unit 70 can be lengthened. Further, the control unit 100 keeps the timing of picking up the printing paper by the paper feed unit 151 at the current reference interval, and keeps the transfer speeds of the plurality of transfer rollers 152, the discharge rollers 153, and the sheet discharge unit 70 at present. It may be faster than the transport speed of. In this case as well, the transport interval (that is, the distance interval) of each of the transferred printing papers can be lengthened. Note that step S16 is an example of the transport interval changing step of the present invention.

After that, when the control unit 100 determines that all the print outputs have been completed (S17), in step S18, the control unit 100 performs a process of restoring the transfer interval and ends a series of processes.

As described above, in the composite machine 1 of the present embodiment, the control unit 100 determines the number of printed papers ejected to the trays 36A and 36B, and the printing paper to be printed is determined by the image forming unit 18. After the image forming process, it is estimated whether or not the printing paper is easily curled, and when it is determined that the printing paper is easily curled and the load capacity is determined to be equal to or higher than a predetermined threshold value, the sheet ejecting unit 70 continuously determines. The transfer of printing paper is controlled by the sheet transfer section 15 of the image forming apparatus 10 and the sheet discharge section 70 of the sheet processing device 30 so that the transfer interval of each print paper to be conveyed is longer than the current interval. To do. As a result, when the curled printing paper is ejected into the trays 36A and 36B and the number of ejected sheets reaches the number indicated by the threshold value, the conveying interval is lengthened. That is, it takes a long time for the next printing paper to be ejected on the curled printing paper. As a result, it is possible to secure a time for the curl of the printing paper to return to its original state, so that the curl does not deteriorate the loading state of the trays 36A and 36B, and the loading state can be stabilized. Therefore, it is possible to prevent the printing paper from falling from the trays 36A and 36B. Further, since the transport interval is a standard interval until the number of ejected sheets reaches the number corresponding to the threshold value, it is possible to suppress a decrease in the transfer efficiency of the sheet.

Further, in the above-described embodiment, a processing example for estimating whether or not the printing paper is likely to be curled based on information about the printing paper (type and size of the printing paper) has been illustrated, but as described above. The curl estimation unit 105 may perform the estimation process in consideration of the printing rate, the air temperature, and the humidity acquired by the control unit 100. For example, in general, the larger the printing rate, the easier it is to curl, and the higher the humidity, the easier it is to curl. Therefore, it is preferable to adjust the threshold value in consideration of the printing rate and the humidity. Specifically, when the average value of the printing rates for a plurality of printing papers is larger than a predetermined reference value, the threshold value is reduced by a predetermined ratio, and the average value of the printing rates is larger than the predetermined reference value. When it is small, the threshold value is increased by a predetermined ratio. Similarly, when the humidity is larger than a predetermined reference value, the threshold value is reduced by a predetermined ratio, and when the humidity is smaller than a predetermined reference value, the threshold value is increased by a predetermined ratio.

Further, since the image forming unit 18 of the present embodiment forms an image by an electrophotographic method, the lower the temperature, the cooler the heat of the printing paper after the image formation and the less likely it is that curling occurs. When is higher than a predetermined reference value, the threshold value may be reduced by a predetermined ratio, and when the temperature is lower than a predetermined reference value, the threshold value may be increased by a predetermined ratio.

Further, when the image forming unit 18 of the present embodiment forms an image by an inkjet recording method, the lower the temperature, the worse the drying of the printing paper after the image formation becomes, and the more likely it is that curling occurs. When the temperature is lower than a predetermined reference value, the threshold value may be reduced by a predetermined ratio, and when the temperature is higher than a predetermined reference value, the threshold value may be increased by a predetermined ratio.

In the above-described embodiment, as an example of the image forming apparatus of the present invention, the multifunction device 1 in which the sheet processing apparatus 30 is connected to the image forming apparatus 10 is illustrated, but the present invention is not limited to this configuration. For example, the image forming apparatus of the present invention may be an image forming apparatus 10 to which the sheet processing apparatus 30 is not connected. In this case, the discharge sheet holding unit 21 of the image forming apparatus 10 is an example of the sheet tray of the present invention, and the sheet transporting unit 15 is an example of the sheet discharging unit of the present invention.

Further, the present invention may be regarded as a sheet transporting device for transporting printing paper on which an image is formed by the image forming apparatus 10. In this case, the sheet transfer device includes at least a control unit 100, a sheet transfer unit 15, or a sheet discharge unit 70.

1: Multifunction device 10: Image forming device 15: Sheet transporting unit 16: Paper feed tray 17: Storage unit 18: Image forming unit 30: Sheet processing device 31: Upper main body 32: Lower main body 33: Drilling unit 35: Staple unit 36A : Upper tray 36B: Lower tray 37: Conveying roller pair 38: Discharge roller pair 39: Discharge roller pair 40: Conveying roller pair 47: Discharge port 48: Discharge port 50, 51, 52: Conveyance path 60: Sheet matching portion 61, 62: Matching member 70: Sheet ejection unit 100: Control unit 101: CPU
102: ROM
103: RAM
104: Load capacity determination unit 105: Curl estimation unit 106: Transfer control unit 110: Storage container 151: Paper feed unit 152: Transfer roller pair 153: Discharge roller pair

Claims (4)

An image forming unit that performs image forming processing on the sheet,
A sheet discharging unit that conveys the sheet after the image forming processing by the image forming unit and discharges it to a predetermined sheet tray, and a sheet discharging unit.
A load capacity determination unit that determines the load capacity of the sheets discharged to the seat tray, and a load capacity determination unit.
A curl estimation unit that estimates whether or not the sheet is a sheet that is easily curled after the image forming process.
When the curl estimation unit determines that the sheet is easily curled, and the load capacity determination unit determines that the load capacity is equal to or higher than a predetermined threshold value, the sheet discharge unit continuously conveys each sheet. An image forming apparatus including a transport control unit for increasing the interval. The claim that the curl estimation unit estimates whether or not a sheet is easily curled based on any one or more of the thickness of the sheet, the size of the sheet, the printing rate of the image formed on the sheet, the temperature, and the humidity. The image forming apparatus according to 1. A sheet discharge unit that transports the sheet after image formation processing and discharges it to a predetermined sheet tray,
A load capacity determination unit that determines the load capacity of the sheets discharged to the seat tray, and a load capacity determination unit.
A curl estimation unit that estimates whether or not the sheet is a sheet that is easily curled after the image forming process.
When the curl estimation unit determines that the sheet is easily curled, and the load capacity determination unit determines that the load capacity is equal to or higher than a predetermined threshold value, the sheet discharge unit continuously conveys each sheet. A seat transfer device including a transfer control unit for increasing the interval. It is a transfer interval adjustment method for adjusting the sheet transfer interval applied to the sheet transfer device.
A load capacity determination step for determining the load capacity of the sheets discharged to a predetermined seat tray after the image formation process, and a load capacity determination step.
A curl estimation step for estimating whether or not the sheet is a sheet that is easily curled after the image forming process, and
When the sheet is determined to be easily curled by the curl estimation step and the load capacity is determined to be equal to or higher than a predetermined threshold value by the load capacity determination step, the sheets are continuously conveyed by the sheet transfer device. A transport interval adjustment method comprising a transport interval change step that changes the interval to be longer.

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