JP2024119740A - Image forming system and static elimination device - Google Patents

Abstract

To suppress a loading failure of a discharged sheet when an insertion sheet is fed from an insertion device.SOLUTION: An image forming system 1 according to the invention has: an image forming device 100 that forms images on sheets; an inserter 300 that inserts an inserted sheet between a plurality of sheets on which the images are formed by the image forming device 100; and a static elimination device 500 having a static elimination roller pair 500a for static elimination of the sheets on which the images are formed by the image forming device 100. The static elimination device 500 performs a static elimination process using the static elimination roller pair 500a on a sheet that is discharged from the image forming device 100 and transported to the static elimination device 500 via a through path 301, but does not perform a static elimination process using the static elimination roller pair 500a on an inserted sheet that is fed from a feed tray 303 and transported to the static elimination device 500 via an insertion transport path 305.SELECTED DRAWING: Figure 5

Description

The present invention relates to an image forming system that forms an image on a sheet and a static elimination device.

Conventionally, in image forming apparatuses such as copiers, sheets on which an image is formed by an image forming unit are stacked on a discharge tray. In such image forming apparatuses, the sheets stacked on the discharge tray may stick to each other due to electrostatic forces between the sheets. In response to this, an image forming system equipped with a static eliminator for eliminating static electricity from the sheets has been proposed. In the image forming system described in Patent Document 1, a static eliminator is disposed downstream (rear stage) of the image forming apparatus. This static eliminator eliminates static electricity from the sheets conveyed from the image forming apparatus, thereby preventing the sheets from sticking to each other on the discharge tray. In addition, a charge adjustment device is known that applies a voltage to every other sheet conveyed and charges the sheets so that their surfaces have the same polarity when stacked, thereby improving stacking defects (see Patent Document 2).

JP 2022-161568 A JP 2022-171206 A

Some image forming systems are equipped with an insertion device that inserts an insertion sheet between multiple sheets on which an image has been formed. The insertion sheet fed from the insertion device is a sheet that the user has prepared in advance. Therefore, if the insertion sheet fed from the insertion device is subjected to the same charge removal process as the sheet transported from the image forming device to the charge removal device, the insertion sheet will unintentionally become charged, resulting in stacking problems. Also, in the charge adjustment device, if the insertion sheet fed from the insertion device is subjected to the same charge adjustment process as the sheet transported from the image forming device to the charge adjustment device, the insertion sheet will unintentionally become charged, resulting in stacking problems.

The present invention aims to prevent improper stacking of ejected sheets when an insertion sheet is fed from the insertion device.

In order to solve the above problem, one aspect of the present invention is an image forming system that includes an image forming device that forms an image on a sheet, an insertion device that is arranged downstream of the image forming device and inserts an insertion sheet between multiple sheets on which an image is formed by the image forming device, and a static elimination device that is arranged downstream of the insertion device and has a static elimination unit that eliminates static electricity from the sheet on which an image is formed by the image forming device, the insertion device having a first conveying path along which a sheet discharged from the image forming device is conveyed to the static elimination device, a feed tray on which the insertion sheets are stacked, and a second conveying path along which the insertion sheets fed from the feed tray are conveyed to the static elimination device, the static elimination device performs a static elimination process by the static elimination unit on a sheet discharged from the image forming device and conveyed to the static elimination device via the first conveying path, and does not perform the static elimination process by the static elimination unit on an insertion sheet fed from the feed tray and conveyed to the static elimination device via the second conveying path.

Another aspect of the present invention includes an image forming apparatus that forms an image on a sheet, an insertion apparatus that is disposed downstream of the image forming apparatus and that inserts an insertion sheet between a plurality of sheets on which an image is formed by the image forming apparatus, and a static elimination apparatus that is disposed downstream of the insertion apparatus and has a static elimination section that eliminates static electricity from the sheet on which an image is formed by the image forming apparatus, the insertion apparatus having a first transport path along which a sheet discharged from the image forming apparatus is transported to the static elimination apparatus, a feed tray on which the insertion sheet is stacked, and a second transport path along which the insertion sheet fed from the feed tray is transported to the static elimination apparatus, the static elimination apparatus being disposed downstream of the image forming apparatus and having a static elimination section that eliminates static electricity from the sheet on which an image is formed by the image forming apparatus. The image forming system is capable of executing a first mode in which the static elimination unit performs the static elimination process on a sheet discharged from the image forming device and transported to the static elimination device via the first transport path, and does not perform the static elimination process on an insertion sheet fed from the feed tray and transported to the static elimination device via the second transport path, and a second mode in which the static elimination unit performs the static elimination process on both a sheet discharged from the image forming device and transported to the static elimination device via the first transport path and an insertion sheet fed from the feed tray and transported to the static elimination device via the second transport path.

Another aspect of the present invention is an image forming system that includes an image forming device that forms an image on a sheet, an insertion device that is arranged downstream of the image forming device and inserts an insertion sheet between multiple sheets on which an image is formed by the image forming device, and a static elimination device that is arranged downstream of the insertion device and has a static elimination unit that eliminates static electricity from the sheet on which an image is formed by the image forming device, the insertion device having a first conveying path along which a sheet discharged from the image forming device is conveyed to the static elimination device, a feed tray on which the insertion sheets are stacked, and a second conveying path along which the insertion sheets fed from the feed tray are conveyed to the static elimination device, the static elimination device performing a static elimination process by the static elimination unit at a first voltage on a sheet discharged from the image forming device and conveyed to the static elimination device via the first conveying path, and performing a static elimination process by the static elimination unit at a second voltage smaller than the first voltage on an insertion sheet fed from the feed tray and conveyed to the static elimination device via the second conveying path.

Another aspect of the present invention is an image forming system that includes an image forming device that forms an image on a sheet, an insertion device that is arranged downstream of the image forming device and inserts an insertion sheet between multiple sheets on which an image is formed by the image forming device, and a charge adjustment device that is arranged downstream of the insertion device and has a charge adjustment unit that performs a charge adjustment process to apply a charge to every other image-formed sheet so that the surface potential of the sheet on which an image is formed by the image forming device is reversed. The insertion device has a first transport path along which sheets discharged from the image forming device are transported to the charge adjustment device, a feed tray on which the insertion sheets are stacked, and a second transport path along which the insertion sheets fed from the feed tray are transported to the charge adjustment device, and the charge adjustment device performs the charge adjustment process by the charge adjustment unit on sheets discharged from the image forming device and transported to the charge adjustment device via the first transport path, and does not perform the charge adjustment process by the charge adjustment unit on insertion sheets fed from the feed tray and transported to the charge adjustment device via the second transport path.

Another aspect of the present invention is a static elimination device that is connected to an image forming device that forms an image on a sheet and an insertion device that inserts an insertion sheet between multiple sheets, and includes a static elimination unit that eliminates static electricity from a sheet on which an image is formed by the image forming device, the static elimination unit performing a static elimination process on a sheet on which an image is formed by the image forming device, and does not perform the static elimination process on an insertion sheet transported from the insertion device.

According to the present invention, when an insertion sheet is fed from the insertion device, it is possible to improve the stackability of the discharged sheet.

FIG. Cross-section of the inserter. FIG. FIG. 2 is a block diagram of a control unit of the image forming system. 4 is a flowchart showing a static elimination operation according to the first embodiment. 10 is a flowchart showing a static elimination operation according to a second embodiment. FIG. 13 is a cross-sectional view of an image forming system according to a fourth embodiment. FIG. 13 is a cross-sectional view of a charge adjustment portion according to a fourth embodiment. 13 shows the fourth embodiment when loaded.

Embodiments of the present disclosure will be described below with reference to the drawings. Unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described in the following embodiments are not intended to limit the scope of application of the present technology to only those.

[First embodiment]
<Image forming system>
An image forming system 1 according to the present embodiment will be described. FIG. 1 is a cross-sectional view showing the structure of the image forming system 1. The image forming system 1 is composed of an image forming apparatus 100, an inserter 300, an operation unit 400, a static eliminator 500, and a finisher 600. The image forming apparatus 100 is composed of an image forming apparatus main body 100a and a fixing device 200, and forms an image on a sheet. The inserter 300 connected to the downstream side of the image forming apparatus 100 inserts an insertion sheet between a plurality of sheets on which an image is formed by the image forming apparatus 100. The static eliminator 500 connected to the downstream side of the inserter 300 eliminates static electricity from the sheet conveyed from the inserter 300. The finisher 600 connected to the downstream side of the static eliminator 500 performs a predetermined post-processing on the sheet conveyed from the static eliminator 500. An operation unit 400 is provided above the fixing device 200 of the image forming apparatus 100, allowing a user to perform various operations on the image forming system 1.

In the image forming system 1 of this embodiment, the image forming device 100 and the inserter 300 are directly connected, but the configuration of the image forming system 1 is not limited to this. For example, an intermediate device that transports a sheet from the image forming device 100 to the inserter 300 may be disposed between the image forming device 100 and the inserter 300. In such a case, all devices disposed upstream of the inserter 300 are collectively referred to as the image forming device of this embodiment.

In addition, in the image forming system 1 of this embodiment, the inserter 300 and the static eliminator 500 are directly connected, but the configuration of the image forming system 1 is not limited to this. For example, an intermediate device that transports a sheet from the inserter 300 to the static eliminator 500 may be disposed between the inserter 300 and the static eliminator 500.

<Image forming apparatus>
Next, the image forming apparatus 100 will be described. The image forming apparatus 100 in this embodiment is a tandem type multifunction machine that employs an intermediate transfer method. The image forming apparatus 100 can form a full-color image on a sheet P (transfer material, sheet material, recording medium, media) such as paper using an electrophotographic method in response to an image signal transmitted from an external device (not shown), for example.

The image forming apparatus main body 100a of the image forming apparatus 100 has a cassette 110 in which sheets P are stored, and a feeding section 111 that feeds the sheets stored in the cassette 110. The sheets P stored in the cassette 110 are separated one by one by the feeding section 111 and fed to a conveying path 120. A plurality of conveying rollers 121 are arranged on the conveying path 120, and the sheets P fed by the feeding section 111 are conveyed to a transfer section 190 by the plurality of conveying rollers 121. In addition, a path sensor 122 is arranged on the conveying path 120 to determine the timing at which the sheets P are conveyed.

The image forming device main body 100a has four image forming units 150Y, 150M, 150C, and 150K as multiple image forming units (stations). Image forming unit 150Y forms a yellow (Y) image, image forming unit 150M forms a magenta (M) image, image forming unit 150C forms a cyan (C) image, and image forming unit 150K forms a black (K) image. These four image forming units 150Y, 150M, 150C, and 150K are arranged in a row along the moving direction of the image transfer surface of the intermediate transfer belt 191.

The image forming unit 150Y has a developing device 151, a primary charger 152, and a photosensitive drum 153. The photosensitive drum 153, which is a photosensitive body that carries a toner image, is rotated by a driving force transmitted from a drum drive motor (not shown). The surface of the rotating photosensitive drum 153 is uniformly charged to a predetermined potential of a predetermined polarity (negative polarity in this embodiment) by the primary charger 152. During charging, a predetermined charging voltage is applied to the primary charger 152 by a charging power source (not shown). The laser scanner 154 as an exposure means irradiates the photosensitive drum 153 with laser light modulated according to image information. The charged surface of the photosensitive drum 153 is scanned and exposed by the laser scanner 154 according to an image signal, and an electrostatic latent image is formed on the photosensitive drum 153. The electrostatic image formed on the photosensitive drum 153 is developed by the developing device 151 as a developing means, and a toner image is formed on the photosensitive drum 153. In this embodiment, toner charged with the same polarity as the charge polarity of the photosensitive drum 153 adheres to the exposed portion of the photosensitive drum 153, which has been uniformly charged and then exposed to light to reduce the absolute value of the potential. The developing unit 151 has a developing roller that carries the developer and transports it to a developing position facing the photosensitive drum 153. During development, a predetermined developing voltage is applied to the developing roller by a developing power source (not shown). Toner is supplied to the developing unit 151 from a toner bottle 131 inserted in a toner bottle unit 130 through a toner pipe (not shown). The toner image visualized on the photosensitive drum 153 is then transferred (primary transfer) onto the intermediate transfer belt 191 by a primary transfer roller to which a voltage of the opposite polarity to the charge polarity of the toner is applied.

The four image forming units 150Y, 150M, 150C, and 150K have the same configuration except for the color of the toner used to form the images, so a description of the image forming units 150M, 150C, and 150K will be omitted. When forming a color image, the image forming units 150Y, 150M, 150C, and 150K sequentially transfer toner images of yellow, magenta, cyan, and black to the intermediate transfer belt 191 so that they are superimposed on each other.

In the transfer section 190, a transfer belt 192 is disposed at a position facing the intermediate transfer belt 191. The transfer belt 192 is pressed against the intermediate transfer belt 191 to form a secondary transfer nip. The toner image formed on the intermediate transfer belt 191 as described above is secondarily transferred to the sheet P conveyed through the conveying path 120 at the secondary transfer nip of the transfer section 190. During the secondary transfer, a secondary transfer voltage, which is a constant-voltage controlled DC voltage of the opposite polarity (positive polarity in this embodiment) to the charge polarity of the toner, is applied to the transfer belt 192 by a secondary transfer power source (not shown). The sheet P on which the secondary transfer has been completed is conveyed to the fixing device 200 by the conveying belt 123.

The fixing device 200 has a fixing unit 210 and a cooler 230. The fixing unit 210 heats and presses the sheet P carrying an unfixed toner image, thereby fixing (melting and bonding) the toner image to the surface of the sheet P. The sheet P with the fixed toner image is transported to the cooler 230 by a transport roller 221 arranged on the transport path 220. A sensor 222 that detects the sheet is arranged on the transport path 220, and the cooler 230 is controlled based on a signal from the sensor 222. The cooler 230 has the function of cooling the sheet P heated by the fixing unit 210.

In the case of face-up printing, in which the sheet P cooled by the cooler 230 is discharged outside the machine with the printed image side facing up, the sheet P is transported to the transport path 224 by the switching unit 223. On the other hand, in the case of face-down printing, in which the sheet P is discharged outside the machine with the printed image side facing down, the sheet P is transported to the reversing transport path 225 by the switching unit 223. In the reversing transport path 225, the sheet P is reversed and transported to the transport path 224. The sheet P transported to the transport path 224 in this manner is discharged from the image forming apparatus 100 and transported to the inserter 300.

In the case of double-sided printing, the sheet P on which printing of the first side (front side) is completed is transported from the inversion transport path 225 to the double-sided transport path 227 by the switching unit 226. The sheet P transported to the double-sided transport path 227 passes through the transport paths 124 and 120 of the image forming apparatus main body 100a and is transported again to the transfer unit 190. The sheet P transported to the transfer unit 190 has an image formed on the second side (back side) in the same manner as the first side. The sheet P on which printing of the second side is completed is discharged from the image forming apparatus 100 through the transport path 224 and transported to the inserter 300.

In this embodiment, the image forming device 100 is composed of the image forming device main body 100a and the fixing device 200, but the fixing device 200 may be integrally arranged inside the housing of the image forming device main body 100a.

<Inserter>
Next, the configuration of the inserter 300 will be described. FIG. 2 is a cross-sectional view of the inserter 300. The inserter 300 is disposed downstream (rear stage) of the image forming apparatus 100. The inserter 300 has a through-path 301 as a first conveying path along which the sheet P discharged from the image forming apparatus 100 is conveyed. An entrance roller 302 and an exit roller 308 are disposed on the through-path 301. The entrance roller 302 receives the sheet P from the image forming apparatus 100 and conveys it along the through-path 301. The exit roller 308 discharges the sheet P from the inserter 300. The sheet P discharged from the inserter 300 is conveyed to a static eliminator 500 disposed downstream of the inserter 300.

The inserter 300 has a feed tray 303 on which the insertion sheets P1 are stacked, and a feed roller 304 that feeds the insertion sheets P1 stacked on the feed tray 303. The inserter 300 also has an insertion conveying path 305 as a second conveying path along which the insertion sheets P1 fed from the feed tray 303 are conveyed. The insertion conveying path 305 merges with the through path 301 at a junction 307. A conveying roller 306 is arranged in the insertion conveying path 305, and the insertion sheets P1 fed by the feed roller 304 are conveyed to the junction 307 by the conveying roller 306. The insertion sheets P1 then pass through the junction 307 and are discharged from the inserter 300 by the exit roller 308. The insertion sheets P1 discharged from the inserter 300 are conveyed to the static eliminator 500 arranged downstream of the inserter 300.

The user can use the operation unit 400 to set the type of insertion sheet P1 loaded on the feed tray 303 of the inserter 300. The operation unit 400 is an example of an acquisition means for acquiring the type of insertion sheet P1 loaded on the feed tray 303. For example, the types of insertion sheet P1 include ordinary paper, a sheet made primarily from synthetic resin (synthetic paper), and special paper with a metal layer vacuum-deposited on the surface (metal-deposited paper).

<Static charge removal device>
Next, the configuration of the static eliminator 500 will be described. FIG. 3 is a cross-sectional view of the static eliminator 500. The static eliminator 500 is disposed downstream of the image forming apparatus 100 and the inserter 300. The static eliminator 500 has a conveying path 501 along which the sheets (sheet P and inserted sheet P1) discharged from the inserter 300 are conveyed. An entrance roller 502 and an exit roller 503 are disposed on the conveying path 501. The entrance roller 502 receives the sheet from the inserter 300 and conveys it along the conveying path 501. The exit roller 503 discharges the sheet from the static eliminator 500. The sheet discharged from the static eliminator 500 is conveyed to a finisher 600 disposed downstream of the static eliminator 500.

The static elimination device 500 has a static elimination roller 504 and a static elimination opposing roller 505. The static elimination roller 504 and the static elimination opposing roller 505 constitute a static elimination roller pair 500a as a static elimination unit that eliminates static electricity from a sheet while in contact with the sheet. A static elimination voltage, which is a constant voltage controlled DC voltage of the opposite polarity (negative polarity in this embodiment) to the transfer belt 192, is applied to the static elimination roller 504 by a static elimination power source 506. The static elimination opposing roller 505 is electrically grounded (connected to ground). The static elimination roller 504 can be moved by a moving mechanism (not shown) between a contact position (position shown by a solid line in FIG. 3) where it contacts the static elimination opposing roller 505 and a separated position (position shown by a dashed line in FIG. 3) where it is separated from the static elimination opposing roller 505. The static elimination roller 504 is moved to the separated position when a sheet that does not require static elimination is transported. The static elimination device 500 may be configured not to have a moving mechanism for moving the static elimination roller 504 between the contact position and the separated position. In other words, the static elimination roller 504 may be in a state of always being in contact with the static elimination opposing roller 505.

Two ionizers 507 and 508 are disposed downstream of the charge removal roller 504. The ionizer 507 is disposed above the conveying path 501, and the ionizer 508 is disposed below the conveying path 501. The ionizers 507 and 508, which serve as non-contact charge removal units, remove charge from the conveyed sheet without contacting the sheet. The ionizers 507 and 508 remove charge from the sheet by irradiating ions toward the sheet conveyed along the conveying path 501. The non-contact charge removal unit is not limited to an ionizer, and it is also possible to use, for example, a corotron having a discharge wire.

The discharge roller pair 500a of this embodiment has a high discharge effect because it contacts the sheet and applies a voltage directly. On the other hand, the discharge roller pair 500a has the characteristic that the surface potential of the discharged sheet varies widely, making the discharge uneven. The discharge effect of the sheet by the ionizers 507 and 508 is smaller than that by the discharge roller pair 500a, but the surface potential of the sheet after discharge processing varies little. Therefore, the ionizers 507 and 508 can even out the surface potential of the sheet that has become uneven due to the discharge roller pair 500a.

<Finisher>
Next, the finisher 600 will be described with reference to FIG. 1. The finisher 600 is disposed downstream of the image forming apparatus 100, the inserter 300, and the static eliminator 500. The finisher 600 discharges the sheets (sheet P and inserted sheet P1) discharged from the static eliminator 500 to the outside of the image forming system 1. The finisher 600 has discharge trays 601 and 602 on which the sheets discharged from the finisher 600 are stacked. The finisher 600 also has a post-processing unit 603 that performs a predetermined post-processing on the sheets. The post-processing unit 603 has functions such as a sheet folding function, a sheet cutting function, a bookbinding function, a sheet binding function, and a sheet punching function. The sheets that have been subjected to the predetermined post-processing by the post-processing unit 603 are discharged to the discharge trays 601 and 602.

<Control Configuration of Image Forming System>
4 is a block diagram of the control unit of the image forming system 1. The image forming apparatus 100 has a printer control unit 160. The printer control unit 160 includes a CPU (Central Processing Unit) 161, a ROM (Read Only Memory) 162, a RAM (Random Access Memory) 163, and an ASIC (Application Specific Integrated Circuit) 164. The CPU 161 executes instructions based on a control program stored in the ROM 162. The ASIC 164 is connected to various loads such as an image forming unit 167, a feed unit 166, and a fixing cooling fan 165, and executes control according to instructions from the CPU 161. The CPU 161 communicates with the CPU 171 of the controller control unit 170 that controls the operation unit 400, and executes control of the image forming apparatus 100 based on input information to the operation unit 400. The operation unit 400 has a display unit that displays information.

The image forming apparatus 100 is provided with a communication IF section (communication interface section) 168 for communicating with the inserter 300, the static eliminator 500, and the finisher 600 connected downstream of the image forming apparatus 100. The CPU 161 is connected to a communication line 180 via the communication IF section 168. The communication line 180 is connected to the inserter 300, the static eliminator 500, and the finisher 600. The communication line 180 includes a parallel signal line including a serial signal line and a power remote signal line. Information is transmitted and received between the apparatuses as serial data via the serial signal line. The CPU 161 can transmit a power remote signal via the power remote signal line to start up the power supplies of the inserter 300, the static eliminator 500, and the finisher 600 connected downstream of the image forming apparatus 100.

The inserter 300 has an inserter control unit 350. The inserter control unit 350 includes a CPU 351, a ROM 352, a RAM 353, and an ASIC 354. The CPU 351 executes commands based on a control program stored in the ROM 352. The ASIC 354 is connected to each load such as the inserter feed unit and the sheet transport unit, and executes control based on commands from the CPU 351. The CPU 351 communicates with the image forming apparatus 100, the static eliminator 500, and the finisher 600 via a communication IF unit 361.

The static eliminator 500 has a static eliminator control unit 550. The static eliminator control unit 550 includes a CPU 551, a ROM 552, a RAM 553, and an ASIC 554. The CPU 551 executes commands based on a control program stored in the ROM 552. The ASIC 554 is connected to various loads such as a sheet conveying unit and a sensor, and executes control based on commands from the CPU 551. The CPU 551 communicates with the image forming apparatus 100, the inserter 300, and the finisher 600 via a communication IF unit 561.

The finisher 600 has a finisher control unit 650. The finisher control unit 650 includes a CPU 651, a ROM 652, a RAM 653, and an ASIC 654. The CPU 651 executes commands based on a control program stored in the ROM 652. The ASIC 654 is connected to various loads such as a post-processing unit and a sheet conveying unit, and executes control based on commands from the CPU 651. The CPU 651 communicates with the image forming apparatus 100, the inserter 300, and the static elimination device 500 via a communication IF unit 661.

<Control of static elimination operation>
When the image forming apparatus 100 forms an image on the sheet P, the sheet P may become charged. The charging characteristics vary depending on the type of sheet, and synthetic paper and metallized paper have a large electrical resistance and are easily charged. If the sheet P is discharged to the discharge trays 601 and 602 while still charged, the sheets P may attract each other due to electrostatic force, causing the sheets to stick to each other. Therefore, the image forming system 1 of the present embodiment uses the static elimination device 500 to eliminate static electricity from the sheet P based on the type of sheet. Specifically, when the sheet P that is image-formed by the image forming apparatus and transported to the static elimination device 500 is a type of paper that is easily charged (e.g., synthetic paper or metallized paper), the sheet P is eliminated by both the pair of static elimination rollers 500a as the static elimination unit and the ionizers 507 and 508 as the non-contact static elimination unit. On the other hand, since plain paper has a smaller electrical resistance than synthetic paper and metallized paper, it is possible to sufficiently eliminate static electricity by only the ionizers 507 and 508 as the non-contact static elimination unit. That is, the sheet P such as plain paper is not neutralized by the neutralization roller pair 500a serving as a neutralization unit. That is, when the sheet P on which an image is formed by the image forming apparatus 100 and which is transported to the neutralization apparatus 500 is of a first type (e.g., synthetic paper or metallized paper), the neutralization apparatus 500 performs a neutralization process on the sheet P by the neutralization roller pair 500a. On the other hand, when the sheet P on which an image is formed by the image forming apparatus and which is transported to the neutralization apparatus 500 is of a second type (e.g., plain paper), the neutralization apparatus 500 does not perform a neutralization process on the sheet P by the neutralization roller pair 500a.

Incidentally, the insertion sheet P1 fed from the feed tray 303 of the inserter 300 is often transported to the charge removal device 500 in an uncharged state. In other words, since the insertion sheet P1 fed from the feed tray 303 of the inserter 300 does not undergo the secondary transfer process in image formation, it is often not charged even if the sheet type is synthetic paper that is easily charged. In such a case, if the insertion sheet P1 is subjected to the same charge removal process as the sheet P on which an image is formed by the image forming device 100, the insertion sheet P1 may be unintentionally charged, causing the sheets to stick to each other. Therefore, in this embodiment, the charge removal device 500 does not perform a charge removal process on the insertion sheet P1 by the charge removal roller pair 500a regardless of the paper type. In other words, the charge removal device 500 performs charge removal by the charge removal roller pair 500a on the sheet P on which an image is formed by the image forming device and which is transported to the charge removal device 500 based on the type of sheet P. On the other hand, the static elimination device 500 does not perform static elimination on the insertion sheet P1 fed from the feed tray 303 of the inserter 300 by the static elimination roller pair 500a, regardless of the type of the insertion sheet P1. For example, a case will be described in which the type of sheet P on which an image is formed by the image forming device and the type of insertion sheet P1 conveyed from the inserter 300 are synthetic paper. The synthetic paper sheet P on which an image is formed by the image forming device is static eliminated by the static elimination roller pair 500a, but the synthetic paper insertion sheet P1 fed from the feed tray 303 of the inserter 300 is not static eliminated by the static elimination roller pair 500a.

The following describes the control of the discharge operation performed by the discharge device 500 when the sheet P on which an image is formed by the image forming device 100 is a type that requires discharge by the discharge roller pair 500a. Figure 5 is a flowchart showing the process of the discharge operation performed by the discharge device 500. In this embodiment, the CPU 551 of the discharge device 500 executes the process of the following flowchart, but for example, the CPU 161 of the image forming device 100 or an external computer (not shown) may execute such process.

When a print job is started in the image forming system 1 by a user's instruction, the CPU 551 of the static elimination device 500 starts the process of the flowchart in FIG. 5. First, the CPU 551 turns on the two ionizers 507 and 508 (S1001). Then, the CPU 551 waits until a sheet is transported from the inserter 300 to the static elimination device 500 (S1002). When the sheet is transported (Yes in S1002), the CPU 551 determines whether the sheet transported from the inserter 300 is the insertion sheet P1 fed from the feed tray 303 of the inserter 300 (S1003). If the sheet transported from the inserter 300 is the insertion sheet P1 (Yes in S1003), the CPU 551 turns off the voltage application to the static elimination roller 504 by the static elimination power source 506 (S1004). Then, the CPU 551 determines whether the discharge roller 504 is separated from the discharge opposing roller 505 (S1005). If the discharge roller 504 is not separated from the discharge opposing roller 505 (No in S1005), the CPU 551 separates the discharge roller 504 from the discharge opposing roller 505 (S1006).

In S1003, if the sheet conveyed from the inserter 300 is a sheet P on which an image has been formed by the image forming apparatus 100 (No in S1003), the CPU 551 determines whether the discharge roller 504 is separated from the discharge counter roller 505 (S1007). If the discharge roller 504 is separated from the discharge counter roller 505 (Yes in S1007), the CPU 551 brings the discharge roller 504 into contact with the discharge counter roller 505 (S1008). Then, the CPU 551 turns on the voltage application to the discharge roller 504 by the discharge power source 506 (S1009), and the discharge roller pair 500a discharges the conveyed sheet P (S1010).

The sheet that has been neutralized by the pair of neutralization rollers 500a is neutralized by the ionizers 507 and 508 (S1011). Note that even if the sheet transported from the inserter 300 is the insertion sheet P1 in S1011, the CPU 551 executes the neutralization process by the ionizers 507 and 508. Thereafter, the CPU 551 transports the sheet to the finisher 600 (S1012). Then, the CPU 551 determines whether or not there is a next sheet (S1013). If there is a next sheet (Yes in S1013), the process returns to S1002. If there is no next sheet (No in S1013), the CPU 551 ends the process of the flowchart.

As described above, the static eliminator 500 performs static elimination processing on the sheet P on which an image is formed by the image forming apparatus 100 using the static eliminator roller pair 500a. In other words, the static eliminator 500 performs static elimination processing on the sheet P discharged from the image forming apparatus 100 and transported to the static eliminator 500 via the through path 301 using the static eliminator roller pair 500a. On the other hand, the static eliminator 500 does not perform static elimination processing on the insertion sheet P1 fed from the feed tray 303 of the inserter 300 using the static eliminator roller pair 500a. In other words, the static eliminator 500 does not perform static elimination processing on the insertion sheet P1 fed from the feed tray 303 and transported to the static eliminator 500 via the insertion transport path 305 using the static eliminator roller pair 500a. This prevents the insertion sheet P from being charged unintentionally, and makes it possible to suppress the sheets from sticking to each other on the discharge trays 601 and 602 when the insertion sheet P1 is fed from the inserter 300.

As described above, the ionizers 507 and 508 can adjust the surface potential of the sheet. Even if the ionizers 507 and 508 perform a static elimination process on the insertion sheet P1, the insertion sheet P1 does not become charged. Therefore, in this embodiment, the ionizers 507 and 508 perform a static elimination process on both the sheet P on which an image is formed by the image forming device 100 and the insertion sheet P1 fed from the feed tray 303. This can further prevent the sheets from sticking to each other on the discharge trays 601 and 602. However, the static elimination device 500 may be controlled not to perform a static elimination process on the insertion sheet P1 by the ionizers 507 and 508.

Second Embodiment
Next, a second embodiment will be described. In the first embodiment, the static eliminator 500 does not perform static elimination processing on the insertion sheet P1 by the static elimination roller pair 500a. In contrast, in the second embodiment, the static eliminator 500 can selectively perform a first mode in which the static elimination processing on the insertion sheet P1 by the static elimination roller pair 500a is not performed, and a second mode in which the static elimination processing on the insertion sheet P1 by the static elimination roller pair 500a is performed. Note that the hardware configuration of the image forming system 1 in the second embodiment is the same as that in the first embodiment, and therefore a description thereof will be omitted.

6 is a flowchart showing the process of the charge removal operation performed by the charge removal device 500 in the second embodiment. When a print job is started by the user in the image forming system 1, the CPU 551 of the charge removal device 500 starts the process of the flowchart in FIG. 6. First, the CPU 551 determines whether or not there is an insertion sheet P1 in the feed tray 303 (S2001). Here, the CPU 551 determines the presence or absence of the insertion sheet P1 by a sheet detection sensor (not shown) provided in the feed tray 303. If there is an insertion sheet P1 in the feed tray 303 (Yes in S2001), the CPU 551 determines whether or not the type of the insertion sheet P1 is a type that requires charge removal by the charge removal roller pair 500a (S2002). Here, the operation unit 400 is configured to be able to input the type of the insertion sheet P1. Based on the type of the insertion sheet P1 acquired by the operation unit 400 as an acquisition unit, the CPU 551 determines whether or not the type of the insertion sheet P1 is a type that requires charge removal by the charge removal roller pair 500a. Examples of the first type of sheet that requires static elimination processing by the static elimination roller pair 500a are sheets (synthetic paper) made primarily from synthetic resin and special paper (metal-deposited paper) with a metal layer vacuum-deposited on the surface of the sheet. Synthetic paper and metal-deposited paper have characteristics that make them prone to charging, so it is desirable for these types of sheets to be neutralized by the static elimination roller pair 500a even if they are the insertion sheet P1. On the other hand, an example of the second type of sheet that does not require static elimination processing by the static elimination roller pair 500a is plain paper.

If the type of the inserted sheet P1 is one that requires de-electrification (Yes in S2002), the CPU 551 turns on the voltage application to the de-electrification roller 504 by the de-electrification power source 506 (S2003). Then, the CPU 551 de-electrifies the conveyed sheet by the pair of de-electrification rollers 500a (S2004). At this time, regardless of whether the sheet being conveyed is the inserted sheet P1 or not, the de-electrification process by the pair of de-electrification rollers 500a is executed. Next, the CPU 551 de-electrifies the sheet by the ionizers 507 and 508 (S2005). Then, the de-electrified sheet is conveyed to the finisher 600 (S2006). If there is a next sheet (Yes in S2007), the process returns to S2004. If there is no next sheet (No in S2007), the CPU 551 ends the process of the flowchart. The above-mentioned S2003 to S2007 are an example of the process in the second mode.

If the type of insertion sheet P1 does not require static elimination in S2002 (No in S2002), the CPU 551 determines whether the sheet conveyed from the inserter 300 is the insertion sheet P1 fed from the feed tray 303 of the inserter 300 (S2008). If the sheet conveyed from the inserter 300 is the insertion sheet P1 (Yes in S2008), the CPU 551 turns off the voltage application to the static elimination roller 504 by the static elimination power source 506 (S2011). In other words, if the sheet being conveyed is the insertion sheet P1, the CPU 551 does not perform static elimination processing by the static elimination roller pair 500a.

If the sheet conveyed from the inserter 300 in S2008 is a sheet P on which an image has been formed by the image forming apparatus 100 (No in S2008), the CPU 551 turns on the voltage application to the discharge roller 504 by the discharge power source 506 (S2010), and the conveyed sheet is discharged by the discharge roller 504 and the discharge counter roller 505 (S2011). That is, if the sheet being conveyed is a sheet P on which an image has been formed by the image forming apparatus 100, the CPU 551 performs a discharge process by the discharge roller pair 500a.

Thereafter, the CPU 551 performs a static elimination process on the sheet using the ionizers 507 and 508 (S2012), and then transports the sheet to the finisher 600 (S2013). Note that even if the sheet transported from the inserter 300 is the insertion sheet P1, the CPU 551 performs a static elimination process using the ionizers 507 and 508. If there is a next sheet (Yes in S2014), the process returns to S2008. If there is no next sheet (No in S2014), the CPU 551 ends the process of the flowchart. The above-mentioned steps S2008 to S2014 are an example of the process in the first mode.

As described above, in the second embodiment, the static eliminator 500 determines whether or not to eliminate static electricity from the insertion sheet P1 by the static elimination roller pair 500a based on the type of the insertion sheet P1 inserted from the inserter 300. When the insertion sheet P1 is of the first type (e.g., synthetic paper or metallized paper), the static eliminator 500 performs static elimination processing on both the sheet P on which an image is formed by the image forming apparatus 100 and the insertion sheet P1 fed from the feed tray 303 by the static elimination roller pair 500a. In this way, the mode in which static elimination processing is performed by the static elimination roller pair 500a on both the sheet P on which an image is formed by the image forming apparatus 100 and the insertion sheet P1 fed from the feed tray 303 is an example of the first mode. On the other hand, when the insertion sheet P1 is of the second type (e.g., plain paper), static elimination processing is not performed by the static elimination roller pair 500a on both the insertion sheet P1 fed from the feed tray 303, as in the first embodiment. In this way, the mode in which the discharge roller pair 500a performs the discharge process on the sheet P on which an image is formed by the image forming apparatus 100, and the discharge roller pair 500a does not perform the discharge process on the insertion sheet P1 is an example of the second mode. Synthetic paper and metallized paper have characteristics that make them easily charged, and these types of sheets may be charged even if they are the insertion sheet P1. However, in the second embodiment, the discharge device 500 determines whether or not to discharge the insertion sheet P1 based on the type of the insertion sheet P1, so the discharge device 500 can appropriately discharge the insertion sheet P1. In addition, if the insertion sheet P1 is of a type that does not require discharge, the discharge roller pair 500a does not perform the discharge process, so it is possible to prevent the sheets from sticking to each other on the discharge trays 601 and 602, as in the first embodiment.

[Third embodiment]
In the first embodiment described above, the charge removal process by the charge removal roller pair 500a is not performed on the insertion sheet P1 fed from the feed tray 303 and transported to the charge removal device 500 via the insertion transport path 305. However, the charge removal device 500 may perform the charge removal process by the charge removal roller pair 500a on the insertion sheet P1 at a voltage that does not charge the insertion sheet P1. In such a case, the charge removal device 500 performs the charge removal process by the charge removal roller pair 500a at a first voltage on the sheet P discharged from the image forming apparatus 100 and transported to the charge removal device 500 via the through path 301. On the other hand, the charge removal process by the charge removal roller pair 500a is performed at a second voltage lower than the first voltage on the insertion sheet P1 fed from the feed tray 303 and transported to the charge removal device 500 via the insertion transport path 305. In this way, by removing the charge from the insertion sheet P1 at a voltage lower than that of the sheet P on which an image is formed, it is possible to suppress the sheets from sticking to each other.

[Fourth embodiment]
Fig. 7 shows an example of an image forming apparatus. The image forming apparatus 100, inserter 300, operation unit 400, and finisher 600 of the image forming apparatus in Fig. 7 are the same as those of the image forming apparatus in Fig. 1, and therefore will not be described. Hereinafter, a charge adjustment apparatus 700 will be described. The charge elimination apparatus 500 in Fig. 1 includes a charge elimination roller 504, a charge elimination counter roller 505, and ionizers 507 and 508, whereas the charge adjustment apparatus 700 in Fig. 7 includes a bias application roller 704, a bias application counter roller 705, and an applied bias control unit 707. In other words, it does not include the ionizers 507 and 508.

Figure 8 is a cross-sectional view showing the configuration of the charge adjustment unit in the image forming apparatus of Figure 7. The charge adjustment unit includes a bias application roller 704 and a bias application opposing roller 705 that contact the sheet P. The bias application roller 704 and the bias application opposing roller 705 constitute a bias application roller pair 700a as a charge adjustment unit that adjusts the charge of the sheet while in contact with the sheet. The bias application opposing roller 705 is electrically grounded (connected to ground). Furthermore, the bias application roller 704 is provided with a charge adjustment power source 706. Regarding the charge adjustment of the sheet P, a case in which the lower surface of the sheet P is positively charged by the application of the secondary transfer voltage will be described. When multiple sheets are continuously image-formed, the applied bias control unit 707 controls the charge adjustment power source 706 to apply a negative voltage to the bias application roller 704 for every other sheet, so that the electrostatic polarity of the sheet surface is inverted and charged. In other words, the bias application roller pair 700a applies a charge of the opposite polarity to the surface potential of the sheet on which the image is formed to the sheet. As a result, the surface potential of the sheet before passing through the bias application roller pair 700a is reversed from the surface potential of the sheet after passing through it. That is, the charge adjustment unit performs a charge adjustment process in which a charge is applied to every other sheet so that the surface potential of the sheet on which an image is formed is reversed. FIG. 9 shows the state during stacking in this embodiment. A case in which the bias application roller pair 700a applies a charge to an even-numbered sheet P will be described. If the first to fourth sheets are Pa to Pd, respectively, Pa and Pc to which no charge is applied in the charge adjustment device 700 are stacked in a state in which the upper surface is negatively charged and the lower surface is positively charged. Pb and Pd, which are charged in the charge adjustment device 700 so that the electrostatic polarity of the sheet surface is reversed, are stacked in a state in which the upper surface is positively charged and the lower surface is negatively charged. In this way, since the sheet surfaces are charged so as to repel each other when stacked, it is possible to prevent the sheets from sticking to each other due to electrostatic force. However, the arrangement of the bias application roller 704 and the bias application opposing roller 705 is not limited to this. A bias application opposing roller 705 that is electrically grounded (connected to ground) may be disposed on the lower surface side of the sheet, and a bias application roller 704 may be disposed on the upper surface side of the sheet. In other words, when the lower surface of the sheet P is positively charged by the application of a voltage for secondary transfer, the upper surface P of the sheet is negatively charged, so that the bias application roller 704 may impart a positive charge to the sheet P from the upper surface side of the sheet.

The insertion sheet P1 fed from the feed tray 303 of the inserter 300 is often transported to the charge adjustment device 700 in an uncharged state. If the insertion sheet P1 is subjected to the same charge adjustment process as the sheet P on which an image is formed by the image forming apparatus 100, the insertion sheet P1 may be excessively charged. Specifically, when the bias application roller pair 700a applies a charge to an even-numbered sheet, if the insertion sheet P1 is transported to the charge adjustment device 700 as an even-numbered sheet and is applied with a charge by the bias application roller pair 700a, the insertion sheet P1 will be excessively charged. This causes excessive repulsion between the sheet surfaces facing the insertion sheet P1 during stacking, resulting in stacking failure. Therefore, the charge adjustment device 700 performs a charge adjustment process by the bias application roller pair 700a on the sheet P on which an image is formed by the image forming apparatus 100, and does not perform a charge adjustment process by the bias application roller pair 700a on the insertion sheet P1. In other words, the charge adjustment device 700 performs charge adjustment processing by the bias application roller pair 700a on the sheet P discharged from the image forming apparatus 100 and transported to the charge adjustment device 700 via the through path 301. On the other hand, the charge adjustment device 700 does not perform charge adjustment processing by the bias application roller pair 700a on the insertion sheet P1 fed from the feed tray 303 of the inserter 300 and transported to the charge adjustment device 700 via the insertion transport path 305. In other words, every other sheet P on which an image is formed is given a charge by the bias application roller pair 700a, and all insertion sheets P1 transported from the inserter 300 are not given a charge by the bias application roller pair 700a. As a result, in the fourth embodiment as in the above embodiment, sheet stacking failure can be suppressed.

REFERENCE SIGNS LIST 1 Image forming system 100 Image forming apparatus 300 Inserter 500 Discharge device 504 Discharge roller 505 Discharge counter roller

Claims (9)

an image forming apparatus for forming an image on a sheet;
an inserting device disposed downstream of the image forming device and configured to insert an insert sheet between a plurality of sheets on which images are formed by the image forming device;
a static elimination device disposed downstream of the insertion device and having a static elimination unit that eliminates static electricity from a sheet on which an image is formed by the image forming device;
Equipped with
the insertion device includes a first conveying path along which the sheet discharged from the image forming device is conveyed to the static elimination device, a feed tray on which the insertion sheets are stacked, and a second conveying path along which the insertion sheets fed from the feed tray are conveyed to the static elimination device;
the static elimination device performs a static elimination process by the static elimination unit on a sheet that is discharged from the image forming apparatus and transported to the static elimination device via the first transport path, and does not perform the static elimination process by the static elimination unit on an insertion sheet that is fed from the feed tray and transported to the static elimination device via the second transport path.
1. An image forming system comprising: The image forming system described in claim 1, characterized in that the static elimination device does not perform the static elimination process by the static elimination section on an inserted sheet fed from the feed tray and transported to the static elimination device via the second transport path regardless of the type of the inserted sheet, and performs the static elimination process by the static elimination section on a sheet discharged from the image forming device and transported to the static elimination device via the first transport path if the sheet is a first type, and does not perform the static elimination process by the static elimination section if the sheet is a second type. an image forming apparatus for forming an image on a sheet;
an inserting device disposed downstream of the image forming device and configured to insert an insert sheet between a plurality of sheets on which images are formed by the image forming device;
a static elimination device disposed downstream of the insertion device and having a static elimination unit that eliminates static electricity from a sheet on which an image is formed by the image forming device;
Equipped with
the insertion device includes a first transport path along which the sheet discharged from the image forming device is transported to the static elimination device, a feed tray on which the insertion sheets are stacked, and a second transport path along which the insertion sheets fed from the feed tray are transported to the static elimination device;
The static elimination device is capable of executing a first mode in which the static elimination process is performed by the static elimination section on a sheet discharged from the image forming device and transported to the static elimination device via the first transport path, and the static elimination process is not performed by the static elimination section on an insertion sheet fed from the feed tray and transported to the static elimination device via the second transport path, and a second mode in which the static elimination process is performed by the static elimination section on both the sheet discharged from the image forming device and transported to the static elimination device via the first transport path and the insertion sheet fed from the feed tray and transported to the static elimination device via the second transport path.
1. An image forming system comprising: An acquisition unit for acquiring a type of the sheet loaded on the sheet feed tray,
The static eliminator selectively executes the first mode and the second mode based on the type of sheet acquired by the acquisition means.
4. The image forming system according to claim 3. the charge removing unit is a pair of charge removing rollers that removes charge from the sheet while being in contact with the sheet,
The static elimination device includes the static elimination roller pair and a non-contact static elimination unit that is disposed downstream of the static elimination roller pair and eliminates static electricity from the sheet without contacting the sheet.
5. The image forming system according to claim 1, wherein the image forming system further comprises: a first image forming unit; The charge removing device removes charge from an insertion sheet that is not subjected to the charge removal process by the charge removing roller pair by the non-contact charge removing unit.
6. The image forming system according to claim 5. an image forming apparatus for forming an image on a sheet;
an inserting device disposed downstream of the image forming device and configured to insert an insert sheet between a plurality of sheets on which images are formed by the image forming device;
a static elimination device disposed downstream of the insertion device and having a static elimination unit that eliminates static electricity from a sheet on which an image is formed by the image forming device;
Equipped with
the insertion device includes a first conveying path along which the sheet discharged from the image forming device is conveyed to the static elimination device, a feed tray on which the insertion sheets are stacked, and a second conveying path along which the insertion sheets fed from the feed tray are conveyed to the static elimination device;
the static elimination device performs a static elimination process by the static elimination unit at a first voltage on a sheet discharged from the image forming apparatus and transported to the static elimination device via the first transport path, and performs the static elimination process by the static elimination unit at a second voltage lower than the first voltage on an insertion sheet fed from the feed tray and transported to the static elimination device via the second transport path.
1. An image forming system comprising: an image forming apparatus for forming an image on a sheet;
an inserting device disposed downstream of the image forming device and configured to insert an insert sheet between a plurality of sheets on which images are formed by the image forming device;
a charge adjustment device disposed downstream of the insertion device and having a charge adjustment unit that performs a charge adjustment process of applying a charge to every other image-formed sheet so that a surface potential of the sheet on which an image is formed by the image forming device is reversed;
Equipped with
the insertion device includes a first transport path along which the sheet discharged from the image forming device is transported to the charge adjustment device, a feed tray on which the insertion sheets are stacked, and a second transport path along which the insertion sheets fed from the feed tray are transported to the charge adjustment device;
the charge adjustment device performs the charge adjustment process by the charge adjustment section on a sheet that has been discharged from the image forming apparatus and transported to the charge adjustment device via the first transport path, and does not perform the charge adjustment process by the charge adjustment section on an insertion sheet that has been fed from the feed tray and transported to the charge adjustment device via the second transport path.
1. An image forming system comprising: A static elimination device is connected to an image forming device that forms an image on a sheet and an insertion device that inserts an insertion sheet between a plurality of sheets, and includes a static elimination unit that eliminates static electricity from the sheet on which an image is formed by the image forming device,
the charge removing unit performs a charge removing process on a sheet on which an image is formed by the image forming device, and does not perform the charge removing process on an insertion sheet conveyed from the insertion device,
A static eliminator characterized by the above.

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