JP2018024482A - Sheet conveyance device and image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove sheet powder from a sheet surface with a simple configuration without complicated control.SOLUTION: A sheet conveyance device 300 includes: a separation roller pair 13 and a feeding roller pair 15 which convey sheets S; a feeding path PS1 which guides the sheets S conveyed by the separation roller pair 13 and the feeding roller pair 15; a CPU 101 which controls the separation roller pair 13 and the feeding roller pair 15 so as to bring the conveyed sheets S into contact with a prescribed bend region R1 of the feeding path PS1; and a gap part 604 which is provided in the sheet contact direction on the downstream side in the conveyance direction D of the sheet contact position 401 of the feeding path PS1 and into which paper powder generated from the conveyed sheets S intrudes.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a sheet conveying apparatus that conveys a sheet and an image forming apparatus such as a facsimile or a printer including the sheet conveying apparatus.

  In an electrophotographic image forming apparatus, paper dust is generated from a conveyed sheet, and when this paper dust adheres to a transfer roller, the paper dust attached to the transfer roller inhibits transfer of the developer onto the sheet. An image defect occurs. In addition, in the electrophotographic image forming apparatus, when the paper dust accumulates on the static elimination needle provided upstream of the transfer roller in order to remove the surface charge of the sheet, the static elimination performance of the static elimination needle is reduced. The cleaning function may deteriorate and cause problems.

  Further, in the ink jet type image forming apparatus, when paper dust adheres to the ink ejection port of the recording head, the ejection of ink is hindered, resulting in an image defect. Such image defects or defects have become more prominent due to the recent increase in the use of recycled sheets for the purpose of saving resources or reducing costs.

  On the other hand, Patent Document 1 discloses a sheet conveying apparatus that includes a paper dust removing roller having an outer peripheral surface that is in contact with a sheet made of a conductive material, and a charging unit that frictionally charges the paper dust removing roller. Yes. The paper dust removing roller rotates while being in contact with the sheet to convey the sheet, and is frictionally charged by the charging unit to adsorb and collect the paper dust on the sheet by static electricity.

  In addition, the sheet conveying device disclosed in Patent Document 1 includes a charge removal state in which the charge is removed while grounding and a charge state in which the charge is performed without grounding so that the paper dust removing roller does not charge more than necessary. And a switching unit for switching between. Here, when the charge amount in the paper dust removing roller is excessive, an electrostatic surge may be generated, and the charged electric charge may be discharged. According to the sheet conveying device disclosed in Patent Document 1, by preventing such discharge due to excessive charging, failure of electronic components can be prevented and paper adsorbed on a paper dust removing roller can be prevented. It is possible to prevent image defects caused by scattering powder in the apparatus.

JP 2015-44640 A

  However, in Patent Document 1, there is a problem that the device configuration and control are complicated because the charge removal state and the charge state are switched.

  An object of the present invention is to provide a sheet conveying apparatus and an image forming apparatus that can remove sheet powder from a sheet with a simple configuration without complicated control.

  The sheet conveying apparatus according to the present invention includes a conveying unit that conveys a sheet, a conveying path that guides the sheet conveyed by the conveying unit, and a sheet that is conveyed abuts a predetermined bending region of the conveying path. A control unit that controls the conveying unit; and a gap that is provided in the sheet contact direction downstream of the sheet contact position of the conveyance path in the sheet contact direction and into which sheet powder generated from the conveyed sheet enters. It is characterized by that.

  An image forming apparatus according to the present invention includes: an image forming unit that forms an image on a sheet; and a sheet conveying device that conveys the sheet to form an image on the sheet by the image forming unit. The conveying device controls the conveying unit to convey a sheet, a conveying path for guiding the sheet conveyed by the conveying unit, and the conveyed sheet to abut a predetermined bending region of the conveying path. And a gap provided in the abutting direction downstream of the sheet abutting position of the conveying path in the abutting direction and into which sheet powder generated from the conveyed sheet enters. .

  According to the present invention, sheet powder can be removed from a sheet with a simple configuration without complicated control.

1 is a cross-sectional view of an image forming apparatus according to Embodiment 1 of the present invention. 1 is a block diagram illustrating a configuration of an image forming apparatus according to Embodiment 1 of the present invention. It is sectional drawing of the sheet conveying apparatus which concerns on Embodiment 1 of this invention. It is a top view of the guide part which concerns on Embodiment 1 of this invention. It is a perspective view of the principal part of the guide which concerns on Embodiment 1 of this invention. It is sectional drawing of the principal part of the guide part which concerns on Embodiment 1 of this invention. It is a flowchart which shows the sheet conveyance speed control process which concerns on Embodiment 1 of this invention. It is a figure which shows the table which concerns on Embodiment 1 of this invention. It is a figure which shows the positional relationship of the soft sheet | seat which concerns on Embodiment 1 of this invention, and a guide part. It is a figure which shows the positional relationship of the hard sheet | seat which concerns on Embodiment 1 of this invention, and a guide part. It is sectional drawing of the verification apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the verification result which concerns on Embodiment 1 of this invention. It is a top view of the modification of the guide part which concerns on Embodiment 1 of this invention. It is sectional drawing of the sheet conveying apparatus which concerns on Embodiment 2 of this invention. It is a top view of the guide part which concerns on Embodiment 2 of this invention. It is sectional drawing of the principal part of the guide part which concerns on Embodiment 2 of this invention. It is a figure which shows the table which concerns on Embodiment 2 of this invention. It is sectional drawing of the sheet conveying apparatus which concerns on Embodiment 3 of this invention. It is a top view of the guide part which concerns on Embodiment 3 of this invention. It is sectional drawing of the principal part of the guide part which concerns on Embodiment 3 of this invention. It is a figure which shows the table which concerns on Embodiment 3 of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
<Configuration of image forming apparatus>
The configuration of the image forming apparatus 1000 according to Embodiment 1 of the present invention will be described in detail with reference to FIGS. 1 and 2.

  The image forming apparatus 1000 includes an image forming unit 100, a CPU 101, a RAM 102, a ROM 103, an image signal control unit 110, and an image reading control unit 120. In addition, the image forming apparatus 1000 includes an image forming control unit 130, an operation / display unit 140, a motor speed control unit 150, and an image reading unit 200.

  The image forming unit 100 forms an image read by the image reading unit 200 on the sheet S under the control of the image forming control unit 130.

  The CPU 101 controls the entire image forming apparatus 1000 based on signals input from the operation / display unit 140. The CPU 101 includes a RAM 102 and a ROM 103. The CPU 101 is connected to the host PC 1 via the external interface 2, and receives image data or transmits a device status with the host PC 1. The CPU 101 is connected to the image signal control unit 110, the image reading control unit 120, the image formation control unit 130, the operation / display unit 140, and the motor speed control unit 150.

  The RAM 102 is used as a storage area for input data or a working storage area.

  The ROM 103 stores programs such as control procedures.

  The image signal control unit 110 processes the image signal input from the image reading control unit 120 via the CPU 100 or the image signal received from the host PC 1 under the control of the CPU 100 and outputs the processed image signal to the image formation control unit 130 via the CPU 101. .

  The image reading control unit 120 controls the operation of the image reading unit 200 according to the control of the CPU 101. The image reading control unit 120 outputs the image signal of the image read by the image reading unit 200 to the image signal control unit 110 via the CPU 101.

  The image forming control unit 130 controls the image forming unit 100 to form an image on the sheet S based on an image signal input from the image signal control unit 110 via the CPU 100.

  The operation / display unit 140 detects an operation by the user, outputs a signal corresponding to the detected operation to the CPU 100, and displays a message to the user under the control of the CPU 100.

  The motor speed control unit 150 controls the conveyance speed of the sheet S according to the type of the sheet S under the control of the CPU 100.

  The image reading unit 200 reads an image of the document E and outputs image data of the read image to the image reading control unit 120, a document feeding unit 220 that feeds the document E to the reading unit 210, It has. The image reading unit 200 operates under the control of the image reading control unit 120.

  Next, the configuration of the image forming unit 100 will be described in more detail with reference to FIG.

  The image forming unit 100 operates under the control of the image forming control unit 130. The image forming unit 100 includes a sheet feeding unit 10, an image forming unit 20, a fixing unit 30, a sheet discharging unit 40, a sheet refeeding unit 50, and a developing unit 60.

  The sheet feeding unit 10 feeds the sheet S to the image forming unit 20. Specifically, the sheet feeding unit 10 includes a feeding cassette 11, a pickup roller 12, a separation roller pair 13, a feeding roller pair 15, a registration roller pair 16, a multi-feed tray 17, and a supply. A roller 18a, a separation pad 18b, and a supply roller pair 19 are provided.

  The feeding cassette 11 stores sheets S in a stacked manner. The feeding of the sheet S from the feeding cassette 11 employs a friction retard method because it is frequently used and productivity is required.

  The pickup roller 12 contacts the uppermost sheet S among the sheets S stored in the feeding cassette 11, and feeds the uppermost sheet S to the separation roller pair 13 by a frictional force when rotating.

  The separation roller pair 13 includes a pair of normal rotation rollers and a reverse rotation roller. When the sheet S fed from the pickup roller 12 is multi-fed, the separated sheet S is separated into one sheet. Then, the sheet is fed to the pair of feeding rollers 15 through the feeding path PS1.

  The pair of feeding rollers 15 is a registration roller that receives the sheet S fed from the separation roller pair 13 via the feeding path PS1 or the sheet S fed from the feeding roller pair 19 via the feeding path PS3. Transport toward pair 16.

  The registration roller pair 16 corrects the skew of the sheet S by causing the leading edge of the sheet S to follow the nip when the rotation is stopped. The registration roller pair 16 is rotated at a predetermined timing to convey the sheet S whose skew has been corrected toward the transfer nip portion N1.

  The multi-feed tray 17 can be stacked with the sheets S stacked thereon. The feeding of the sheets S from the multi-feed tray 17 employs a pad retard system (FR system) in order to handle more types of sheets S than the feeding cassette 11.

  The supply roller 18 a and the separation pad 18 b separate the sheets S stacked on the multi-feed tray 17 and supply them to the supply roller pair 19.

  The supply roller pair 19 supplies the sheet S supplied from the supply roller 18a and the separation pad 18b to the feed roller pair 15 via the feed path PS3.

  The image forming unit 20 forms an image on the sheet S fed from the sheet feeding unit 10 and conveys the sheet S on which the image has been formed toward the fixing unit 30. Specifically, the image forming unit 20 includes a photosensitive drum 21, a charging roller 22, a laser unit 23, and a transfer roller 25.

  The surface of the photosensitive drum 21 is uniformly charged by the charging roller 22. When the photosensitive drum 21 is irradiated with laser light corresponding to the image information from the laser unit 23, the charge charged by the charging roller 22 in the portion irradiated with the laser light is removed, and the static corresponding to the image information is removed. An electrostatic latent image is formed.

  The charging roller 22 charges the surface of the photosensitive drum 21 when a predetermined bias voltage is applied.

  The laser unit 23 irradiates the surface of the photosensitive drum 21 with laser light based on the image data of the image read by the image reading unit 200 or the image data transmitted from the host PC 1. The laser unit 23 forms an electrostatic latent image corresponding to the image data in the portion irradiated with the laser light on the surface of the photosensitive drum 21.

  The transfer roller 25 is in contact with the photosensitive drum 21 to form a transfer nip portion N1. The transfer roller 25 rotates with the photosensitive drum 21 and conveys the sheet S conveyed from the registration roller pair 16 to the transfer nip portion N1 at a predetermined timing. The transfer roller 25 applies a bias voltage to the photosensitive drum 21 to transfer the developer image formed on the photosensitive drum 21 to the sheet S in the transfer nip portion N1. The transfer roller 25 sandwiches the sheet S with the photosensitive drum 21 at the transfer nip N1 and conveys the sheet S toward the fixing unit 30.

  The fixing unit 30 fixes the developer image formed on the sheet S conveyed from the image forming unit 20 to the sheet S, and conveys the sheet S on which the developer image is fixed toward the sheet discharge unit 40. . Specifically, the fixing unit 30 includes a fixing roller 31 and a pressure roller 32.

  The fixing roller 31 is made of aluminum or the like, and is heated to a predetermined temperature by a heat source such as a halogen lamp (not shown).

  The pressure roller 32 is in contact with the fixing roller 31 and presses the fixing roller 31 with a predetermined pressure to form a fixing nip portion N2. The pressure roller 32 fixes the developer image on the sheet S by heating and pressing the sheet on which the developer image conveyed from the transfer nip portion N1 is formed with the fixing roller 31 in the fixing nip portion N2. Let The pressure roller 32 conveys the sheet S on which the developer image is fixed toward the sheet discharge unit 40.

  Note that the fixing unit 30 does not have to be a heating roller type that is heated by the fixing roller 31. For example, on-demand fixing in which a fixing nip portion N2 is formed by pressurizing a heat source such as a ceramic heater through an endless film and the fixing nip portion N2 is formed and the sheet S is nipped and conveyed by the fixing nip portion N2. A method may be used.

  The sheet discharge unit 40 discharges the sheet S conveyed from the fixing unit 30 to the outside. The sheet discharge unit 40 conveys the sheet S conveyed from the fixing unit 30 toward the sheet refeeding unit 50. Specifically, the sheet discharge unit 40 includes a discharge roller pair 41 and a discharge tray 42.

  The discharge roller pair 41 discharges the sheet S conveyed from the fixing nip portion N2 to the discharge tray 42. When forming images on both sides of the sheet S, the discharge roller pair 41 temporarily stops before the trailing edge of the sheet S on which the image is formed on one side is removed, and then reversely rotates to reverse the sheet S. Then, the sheet is conveyed toward the sheet refeeding unit 50.

  The discharge tray 42 stacks the sheets S discharged from the discharge roller pair 41.

  The sheet refeeding unit 50 is provided in the image forming unit 100 along with the fixing unit 30. The sheet re-feeding unit 50 directs the sheet S conveyed from the sheet discharge unit 40 toward the image forming unit 20 in order to form an image on the other side of the sheet S on which an image is formed on one side. Transport. Specifically, the sheet refeeding unit 50 includes a refeeding roller pair 51a, a refeeding roller pair 51b, and a refeeding roller pair 51c.

  The refeed roller pair 51a sandwiches and conveys the sheet S conveyed from the discharge roller pair 41 toward the refeed roller pair 51b via the refeed path PS2.

  The refeed roller pair 51b sandwiches and conveys the sheet S conveyed from the refeed roller pair 51a toward the refeed roller pair 51c via the refeed path PS2.

  The refeed roller pair 51c conveys the sheet S conveyed from the refeed roller pair 51b via the refeed path PS2 toward the registration roller pair 16.

  The developing unit 60 includes a developing roller 72, and supplies the developer to the electrostatic latent image formed on the photosensitive drum 21 by the developing roller 72 to generate a developer image on the photosensitive drum 21.

<Configuration of sheet conveying device>
The configuration of the sheet conveying apparatus 300 according to the first embodiment of the present invention will be described in detail with reference to FIG.

  The sheet conveying apparatus 300 is provided in the cassette feeding unit vicinity area A of FIG. Specifically, the sheet conveying apparatus 300 includes a feeding path PS1, a separation roller pair 13, a feeding roller pair 15, a CPU 101, a motor speed control unit 150, a collection container 305, a guide unit G1, have. The separation roller pair 13 and the feeding roller pair 15 constitute a conveying unit.

  A feeding path PS1 that is a conveyance path guides the conveyed sheet S.

  The separation roller pair 13 serving as the first sheet conveying unit includes a feed roller 301 and a retard roller 303. The separation roller pair 13 is provided on the upstream side in the transport direction D with respect to the bending region R1 of the feeding path PS1.

  The feed roller 301 sends out the sheet S in contact with the feed roller 301 among the sheets S fed from the pickup roller 12 to the feeding path PS1.

  The retard roller 303 is pressed against the feed roller 301 to form a pressure contact portion, and a rotational driving force is applied in a direction opposite to the stop or sheet S conveyance direction via a torque limiter. When only one sheet S passes through the pressure contact portion, the retard roller 303 is rotated in the conveying direction of the sheet S by the slip of the torque limiter and sandwiches the sheet S together with the feed roller 301. Then transport. When two or more sheets S are about to pass through the pressure contact portion, the retard roller 303 stops or rotates in a direction opposite to the conveying direction of the sheet S, and moves the sheet S in contact with the retard roller 303. The sheet S is returned to the feeding cassette 11 to prevent double feeding of the sheet S.

  The feed roller pair 15 as the second sheet conveying unit includes a feed roller 302 and a driven roller 304. The feed roller pair 15 is provided on the downstream side in the transport direction D with respect to the bending region R1 of the feed path PS1.

  The feeding roller 302 is provided with a rotational driving force and conveys the sheet S conveyed from the feeding path PS1 toward the registration roller pair 16.

  The driven roller 304 is rotated by the rotation of the feeding roller 302, and the sheet S conveyed from the feeding path PS <b> 1 is nipped together with the feeding roller 302 and conveyed toward the registration roller pair 16.

  The CPU 101 as control means controls the motor speed control unit 150 so that the conveyed sheet S comes into contact with a predetermined bending region R1 of the feeding path PS1.

  The motor speed control unit 150 controls the rotational speeds of the separation roller pair 13 and the feeding roller pair 15 according to the control of the CPU 101, thereby bringing the conveyed sheet S into contact with a predetermined bending region R1 of the feeding path PS1. Let

  The collection container 305 is provided below the guide portion G1, and stores and collects the sheet powder that has been removed from the sheet S by the guide portion G1 and dropped. The collection container 305 is preferably provided so as to be removable so that the collected sheet powder can be cleaned.

  The guide portion G1 is provided on the outer peripheral side of the bending region R1 of the feeding path PS1, and removes the sheet powder of the sheet S by rubbing against the surface of the sheet S passing through the feeding path PS1.

<Configuration of guide section>
In recent years, a lot of recycled sheets that are likely to generate sheet powder are used. In particular, when separating the multi-feed sheet S, a large amount of sheet powder is generated from the surface of the sheet S that rubs against the retard roller 303. Therefore, a guide portion G1 is provided in order to suppress problems caused by the sheet powder.

  The configuration of the guide part G1 according to the first embodiment of the present invention will be described in detail with reference to FIGS.

  The guide part G <b> 1 includes an opening 403, an inclined part 501, a contact surface 502, an edge 601, an edge 603, and a gap part 604.

  A plurality of openings 403 are provided in the contact surface 502 and provided in a plurality. The opening 403 is provided at a position 402 (see FIG. 4) that coincides with the position of the retard roller 303 in the transport direction D of the sheet S in order to collect the sheet powder generated on the sheet S by the retard roller 303. The opening 403 is provided on the downstream side in the transport direction D of the sheet S from the sheet contact position 401 (see FIG. 4) that contacts the sheet S at the beginning of the guide part G1.

  The inclined portion 501 is inclined in the direction away from the abutting sheet S toward the upstream side in the conveyance direction D from the edge 603 on the downstream side in the conveyance direction D of the gap portion 604.

  The abutting surface 502 is formed of a resin material that is textured and has conductivity. The contact surface 502 is grounded to a sheet metal (not shown) of the image forming apparatus 1000. The contact surface 502 is in contact with the surface of the sheet S conveyed through the feeding path PS1.

  An edge 601 is an edge on the upstream side in the conveyance direction D of the sheet S of the opening 403. The edge 601 is exposed to the contact surface 502 and extends in the direction intersecting the transport direction D along the contact surface 502, and is capable of sliding on the surface of the sheet S transported through the feeding path PS1. The edge 601 is preferably extended in a direction orthogonal to the transport direction D.

  The edge 603 is an edge on the downstream side in the conveyance direction D of the sheet S of the opening 403, and is provided to face the edge 601. The edge 603 is exposed to the contact surface 502 and extends in the direction intersecting the transport direction D along the contact surface 502, and can be slid on the surface of the sheet S transported through the feeding path PS1. The edge 603 is preferably extended in a direction orthogonal to the transport direction D.

  The gap portion 604 is provided in the sheet contact direction downstream of the sheet contact position 401 of the feeding path PS1 in the transport direction D, and the sheet powder generated from the transported sheet S enters. The gap portion 604 extends in a direction intersecting the conveyance direction D along the contact surface 502 with the sheet S at the sheet contact position 401. The gap 604 communicates the opening 403 and the outside of the feeding path PS1. The inner wall 605 of the gap portion 604 is preferably perpendicular to the conveyance direction D of the sheet S.

<Sheet conveyance speed control processing>
The sheet conveyance speed control process according to the first embodiment of the present invention will be described in detail with reference to FIGS.

  In the sheet conveyance speed control processing, information on the sheet S is input to the operation / display unit 140 by a user operation, and a signal corresponding to the user operation is output from the operation / display unit 140 to the CPU 100. Be started. The information on the sheet S is information on the sheet S stored in the feeding cassette 11 or the sheet S placed on the multi-feed tray 17.

  First, the CPU 100 acquires information on the type of the sheet S from a signal input from the operation / display unit 140 (S1).

  Next, the CPU 100 refers to the table stored in the ROM 103 (S2). Specifically, the CPU 100 refers to the table shown in FIG.

  Next, the CPU 100 determines the conveying speed of the separation roller pair 13 based on the table reference result (S3). Specifically, the CPU 100 determines the conveyance speed of the separation roller pair 13 corresponding to the acquired types S, a, b, c, and d of the sheet S in the table shown in FIG. For example, when the type of the sheet S is b, the CPU 101 determines 243.2 mm / sec as the conveyance speed of the separation roller pair 13.

  Next, the CPU 100 determines the conveying speed of the feeding roller pair 15 based on the table reference result (S4). Specifically, the CPU 100 determines the conveyance speed of the pair of feeding rollers 15 corresponding to the types a, b, c, and d of the acquired sheet S in the table shown in FIG. For example, when the type of the sheet S is “c”, the CPU 101 determines 230.0 mm / sec as the conveyance speed of the pair of feeding rollers 15.

  Then, after the process of S4 ends, the sheet conveyance speed control process ends.

  Here, in the table shown in FIG. 8, the types of sheets S are classified into four types, a, b, c, and d, according to the sheets S handled by the feeding cassette 11 or the multi-feed tray 17. In the table shown in FIG. 8, the conveyance speed corresponding to the type of the sheet S is set.

  The sheet S of type d in which special processing is applied to the surface of a sheet such as coated paper is peeled off the coating layer on the contact surface 502 when it is greatly curved or rubs strongly against the contact surface 502, etc. Alternatively, the contact surface 502 may be damaged. Therefore, in the table shown in FIG. 8, in order to prevent the sheet S of type d from sliding on the contact surface 502 as much as possible, the conveying speed of the separation roller pair 13 associated with the type d and the type d are set. The conveying speed of the pair of feeding rollers 15 associated with each other is the same.

  On the other hand, in the table shown in FIG. 8, in order to surely slide the sheets S of types a, b, and c against the contact surface 502, the conveying speed of the separation roller pair 13 is higher than the conveying speed of the feeding roller pair 15. Make it faster. As a result, the sheet S can be curved using the difference in the conveyance speed between the separation roller pair 13 and the feeding roller pair 15, so that the contact state between the contact surface 502 of the guide portion G1 and the surface of the sheet S Can be maintained.

  The types a, b, and c of the sheet S in the table shown in FIG. 8 are determined according to the basis weight (g / m 2) of the sheet S input to the operation / display unit 140. In addition, when the separation speed between the separation roller pair 13 and the feeding roller pair 15 is too large, the sheet S is bent and the feeding path PS1 is clogged. Therefore, the conveyance speed of the separation roller pair 13 and the feeding roller pair 15 in the table shown in FIG. 8 is set according to the hardness or rigidity of the sheet S.

  Even if the basis weight of the sheet is the same as in recycled paper and special paper, the hardness of the sheet may be different, so the sheet S may be classified based on Clark stiffness. At this time, the sheet having a low water content tends to have high rigidity, and the sheet having a high water content tends to have low rigidity. Since the Clark rigidity varies depending on the moisture absorption of the sheet, a table may be provided for each environment in which image formation is performed. .

  Further, when a long size sheet such as roll paper is handled, when the conveyance speed difference is provided between the separation roller pair 13 and the feeding roller pair 15, the curvature of the sheet S gradually increases, There is a possibility of causing conveyance failure. Therefore, when handling a long size sheet, the conveyance speed of the separation roller pair 13 and the feeding roller pair 15 is controlled so that the bending amount of the sheet S does not exceed a predetermined amount.

  Further, the amount of sheet powder flying from the sheet S varies greatly depending on the humidity. That is, a lot of sheet powders fly in an environment with low humidity, and the flight is suppressed by moisture in an environment with high humidity. Accordingly, the conveyance speed difference between the separation roller pair 13 and the feeding roller pair 15 may be controlled based on a detected humidity value detected by a humidity sensor (not shown) provided in the image forming apparatus 1000.

  Specifically, in order to press the sheet S against the opening 403 in a low humidity environment, the difference in transport speed between the separation roller pair 13 and the feeding roller pair 15 in a low humidity environment is compared with that in a high humidity environment. You may enlarge it. On the other hand, since the sheet powder removal effect by the guide portion G1 is reduced in a high humidity environment, the difference in conveyance speed between the separation roller pair 13 and the feeding roller pair 15 in a high humidity environment is smaller than that in a low humidity environment. May be.

<Operation of sheet conveying apparatus>
The operation of the sheet conveying apparatus 300 according to the first embodiment of the present invention will be described in detail with reference to FIGS. 9 and 10.

  First, the operation of the sheet conveying apparatus 300 when conveying the soft sheet S will be described with reference to FIG.

  First, as illustrated in FIG. 9A, the sheet S is conveyed in the direction of the arrow 901, thereby contacting the guide portion G <b> 1 at the sheet contact position 401.

  Next, as shown in FIG. 9B, the sheet S is conveyed in the direction of the arrow 902 along the contact surface 502 while being rubbed against the contact surface 502 of the guide portion G1 because it is soft.

  Next, as shown in FIG. 9C, the leading edge of the sheet S passes through the end portion 903 on the downstream side in the transport direction D of the guide portion G1.

  Next, as shown in FIG. 9 (d), the leading edge of the sheet S passes through the feeding roller pair 15 and is sandwiched between the separation roller pair 13 and the feeding roller pair 15 in the conveyance direction D. Be transported. At this time, since it is necessary to keep the sheet S and the contact surface 502 in contact with each other in order to remove the sheet powder, the transport speed of the separation roller pair 13 is set higher than the transport speed of the feed roller pair 15. Make it faster. As a result, the sheet S bends toward the contact surface 502 due to the difference in conveying speed between the separation roller pair 13 and the feeding roller pair 15, and with a larger contact pressure against the contact surface 502 in the bending region R1. Abut.

  The sheet powder on the surface of the sheet S flies from the surface of the sheet S when the contact pressure from the contact surface 502 is released when the sheet S passes the edge 601. Further, the sheet S is conveyed while being rubbed against the edges 601 and 603, whereby the sheet powder on the surface of the sheet S is removed.

  The flying or removed sheet powder is guided to the back side of the guide part G1 through the opening 403 and the gap part 604 due to the influence of the airflow flowing in the direction of the arrow 602 in FIG. The sheet powder guided to the back side of the guide part G1 is accommodated in a collection container 305 provided below the guide part G1. As described above, by providing the gap portion 604 that communicates the opening 403 and the outside of the guide portion G1, the sheet powder flying from the sheet S or the sheet powder removed from the sheet S can be reliably collected.

  In the above operation, by providing the inclined portion 501 in the guide portion G1, it is possible to avoid the leading edge of the sheet S conveyed in the conveying direction D from being caught by the opening 403. Here, the inclined portion 501 has an inclination angle at which the sheet S having the least stiffness (low Clark stiffness) among the sheets S handled by the image forming apparatus 1000 is not caught by the opening 403.

  In addition, the contact resistance of the sheet S with respect to the contact surface 502 can be lowered by applying a texture to the contact surface 502 of the guide portion G1. In addition, by forming the guide portion G1 from a conductive material and grounding it, charging of the guide portion G1 due to rubbing between the sheet S and the contact surface 502 can be suppressed. Accordingly, sticking of the sheet S to the contact surface 502 can be prevented, and conveyance failure of the sheet S can be prevented. In particular, when the moisture-absorbed sheet S is conveyed, the contact area between the sheet S and the contact surface 502 becomes large, and thus the above-described effect becomes remarkable.

  Next, the operation of the sheet conveying apparatus 300 when conveying the hard sheet S will be described with reference to FIG.

  First, as illustrated in FIG. 10A, the sheet S is conveyed in the direction of the arrow 1001, thereby contacting the guide portion G <b> 1 at the sheet contact position 401.

  Next, the sheet S is conveyed in the direction of the arrow 1002 along the contact surface 502 as shown in FIG. At this time, the sheet S is hard and does not come into contact with the opening 403.

  Next, as shown in FIG. 10C, the leading edge of the sheet S passes through the end portion 903 on the downstream side in the transport direction D of the guide portion G1. At this time, the sheet S is hard and does not come into contact with the opening 403.

  Next, as shown in FIG. 10 (d), the leading edge of the sheet S passes through the feeding roller pair 15 and is sandwiched between the separation roller pair 13 and the feeding roller pair 15 in the conveyance direction D. Be transported. At this time, in order to remove the sheet powder, it is necessary to keep the sheet S and the contact surface 502 in contact with each other. For this reason, the conveyance speed of the separation roller pair 13 is made faster than the conveyance speed of the feeding roller pair 15 and is equal to or greater than the conveyance speed difference between the separation roller pair 13 and the feeding roller pair 15 set by the soft sheet S. Provide a transfer speed difference. As a result, the hard sheet S bends toward the contact surface 502 due to the difference in conveying speed between the separation roller pair 13 and the feeding roller pair 15, and a larger contact pressure is applied to the contact surface 502 in the bending region R1. Abut.

  Thus, by conveying the sheet S at a speed corresponding to the type of the sheet S, the sheet S can be brought into contact with the contact surface 502 with a large contact pressure regardless of the type of the sheet S. Powder can be reliably removed.

  In an inkjet image forming apparatus, recording is performed by ejecting ink droplets from a recording head, so that recording can be performed on the sheet S without contact. However, when the sheet powder flying from the sheet S adheres to the ink ejection port, the ejection of ink droplets is hindered, resulting in an image defect. Therefore, in order to eliminate image defects, it is necessary to frequently perform a cleaning operation. The sheet conveying apparatus 300 according to the present embodiment can also be applied to an inkjet image forming apparatus, and can solve the above-described image defects in the inkjet image forming apparatus.

  The sheet powder removing effect of the sheet conveying apparatus 300 in the present embodiment was verified using the verification apparatus shown in FIG.

  The verification apparatus shown in FIG. 11 is configured such that the sheet 1603 is sandwiched between the conveyance path 1601 and the conveyance path 1602 and the sheet 1603 can be conveyed in the conveyance direction D by the conveyance roller pair 1604. Further, as the sheet 1603, a sheet powder spread and adhered in advance is used so that the rising of the sheet powder can be easily confirmed. Furthermore, in order to confirm the effect of removing the sheet powder by the contact pressure of the guide part G1 with respect to the sheet S, a weight 1607 having a different weight is installed on the upper part of the conveyance path 1602.

  In FIG. 11, a conveyance path 1602 having an opening 1605 plays the same role as the guide part G1. In FIG. 11B, assuming a case where the upstream edge of the opening 1605 in the conveyance direction D is not in contact with the sheet, a non-contact region 1608 is provided on the upstream side of the opening 1605 in the conveyance direction D. Yes. In FIG. 12C, assuming that the edge of the opening 1605 on the downstream side in the conveyance direction D is not in contact with the sheet 1603 in addition to the upstream side in the conveyance direction D of the opening 1605, the conveyance direction is assumed. A non-contact region 1609 is provided on the downstream side of the opening 1605 of D.

  By using a high-speed camera for observation, the flying height of the sheet powder 1606 rising from the opening 1605 during the conveyance of the sheet 1603 was analyzed. It can be said that the higher the flying of the sheet powder, the higher the sheet powder removing effect.

  FIG. 12 shows the result of verification using the verification apparatus of FIG. 12, Q1 indicates a verification result using the verification device of FIG. 11A, Q2 indicates a verification result using the verification device of FIG. 11B, and Q3 indicates a verification device of FIG. 11C. The verification result using is shown.

  From FIG. 12, it was confirmed that the higher the weight of the weight 1607, the higher the height of the sheet powder 1606 rising from the sheet 1603. Therefore, it was confirmed that the sheet powder removal effect was larger as the sheet 1603 was rubbed against the opening 1605 with a larger contact pressure. From FIG. 12, it was confirmed that the edge of the sheet 1603 in contact with the opening 1605 was closer to the opening 1605 and the effect of removing the sheet powder was greater. Moreover, in order to remove sheet powder from the opening 1605, it was confirmed that it is better not to provide an opening other than the opening 1605.

  In addition, the structure shown in FIG. 13 may be sufficient as the guide part in this Embodiment not only the structure shown in FIG. 13 is not limited to the position 402 that coincides with the position of the retard roller 303 in the conveyance direction D of the sheet S, but the opening 403a at a position corresponding to the size of the sheet S handled by the feeding cassette 11. Is provided. Thereby, the guide part G2 which has the structure of FIG. 13 can collect | recover the sheet powder adhering to the sheet | seat S from the beginning other than the sheet powder produced by conveyance.

  As described above, the present embodiment includes the CPU 101 that controls the separation roller pair 13 and the feeding roller pair 15 so that the conveyed sheet S contacts the predetermined bending region R1 of the feeding path PS1. In addition, a gap portion 604 that is provided in the sheet contact direction on the downstream side of the conveyance direction D of the sheet contact position 401 of the feeding path PS1 and into which the sheet powder generated from the sheet S enters. Thereby, the sheet powder can be removed from the sheet with a simple configuration without complicated control.

  Further, according to the present embodiment, by providing the edge 601 and the edge 603 at the edge of the opening 403, the sheet powder of the sheet S is removed at the edge 601 and the edge 603 without hindering the conveyance of the sheet S. Can do.

  Further, according to the present embodiment, the sheet powder in the direction intersecting with the conveyance direction is provided because the gap portion 604 extends in the direction intersecting with the conveyance direction along the contact surface 502 with the sheet S. Can be removed.

  In the present embodiment, the inclined portion 501 is inclined at a predetermined angle. However, the inclined portion 501 does not need to be inclined, and may have a curved shape that protrudes upward.

(Embodiment 2)
The configuration of the image forming apparatus according to the second embodiment of the present invention is the same as that shown in FIGS. 1 and 2 except that the sheet conveying apparatus 400 is provided instead of the sheet conveying apparatus 300, and the description thereof is omitted.

<Configuration of sheet conveying device>
The configuration of the sheet conveying apparatus 400 according to the second embodiment of the present invention will be described in detail with reference to FIG.

  In FIG. 14, parts having the same configuration as in FIG.

  The sheet conveying apparatus 400 is provided in the vicinity area B of the multi-tray sheet feeding unit in FIG. Specifically, the sheet conveying apparatus 400 includes a feeding path PS3, a feeding roller pair 15, a supply roller pair 19, a CPU 101, and a motor speed control unit 150. The sheet conveying apparatus 400 includes a sheet powder suction port 1005, a sheet powder collection path 1006, a suction unit 1007, and a guide unit G3.

  A feeding path PS3 that is a conveyance path guides the conveyed sheet S.

  The feed roller pair 15 as the second sheet conveying unit includes a feed roller 302 and a driven roller 304. The feed roller pair 15 is provided on the downstream side in the transport direction D with respect to the bending region R2 of the feed path PS3.

  The supply roller pair 19 includes a supply roller 1003 and a supply roller that hold the sheet S supplied from the supply roller 18a and the separation pad 18b as a first sheet conveyance unit and convey the sheet S in the conveyance direction D by rotation. 1004. The supply roller pair 19 is provided on the upstream side in the transport direction D with respect to the bending region R2 of the feed path PS3.

  The motor speed control unit 150 controls the rotational speeds of the feeding roller pair 15 and the supply roller pair 19 according to the control of the CPU 101, thereby bringing the conveyed sheet S into contact with a predetermined bending region R2 of the feeding path PS3. Let

  The sheet powder suction port 1005 sucks the sheet powder removed from the sheet S by the guide part G3. The sheet powder suction port 1005 is preferably as close to the guide portion G3 as possible in order to enhance the sheet powder collection effect.

  The sheet powder collection path 1006 connects the sheet powder suction port 1005 and the suction unit 1007.

  The suction unit 1007 includes a sheet powder storage unit (not shown), and collects the sheet powder sucked by the sheet powder suction port 1005 by storing the sheet powder in the sheet powder storage unit via the sheet powder recovery path 1006.

  The guide part G3 is provided on the inner peripheral side of the bending region of the feeding path PS3, and removes the sheet powder of the sheet S by rubbing against the surface of the sheet S passing through the feeding path PS3.

<Configuration of guide section>
The configuration of the guide part G3 according to Embodiment 2 of the present invention will be described in detail with reference to FIGS.

  The guide part G3 includes an opening 1102, an inclined part 1201, a contact surface 1202, an edge 1203, an edge 1204, and a gap part 1205.

  A plurality of openings 1102 are provided in the contact surface 1202 and are provided. The opening 1102 is provided at a position corresponding to the size of the sheet S handled by the multi-feed tray 17. The opening 1102 is provided on the downstream side in the transport direction D of the sheet S from the sheet contact position 1101 that contacts the sheet S at the beginning of the guide part G3.

  The inclined portion 1201 is inclined in the direction away from the abutting sheet S toward the upstream side in the conveying direction D from the edge 1204 on the downstream side in the conveying direction D of the gap portion 1205. .

  The abutting surface 1202 is formed of a resin material that has been subjected to texture processing and has conductivity. The contact surface 1202 is grounded to a sheet metal (not shown) of the image forming apparatus 1000. The contact surface 1202 contacts the surface of the sheet S conveyed through the feeding path PS3.

  The edge 1203 is provided on the upstream edge of the opening 1102 in the transport direction D of the sheet S. The edge 1203 is exposed to the contact surface 1202 and extends along the contact surface 1202 in the direction intersecting the transport direction D, and can slide on the surface of the sheet S transported through the feeding path PS3. The edge 1203 is preferably extended in a direction orthogonal to the transport direction D.

  The edge 1204 is provided on the edge of the opening 1102 on the downstream side in the conveyance direction D of the sheet S, and is provided to face the edge 1203. The edge 1204 is exposed to the contact surface 1202 and extends in the direction intersecting the transport direction D along the contact surface 1202, and is slidable on the surface of the sheet S transported through the feeding path PS3. The edge 1204 is preferably extended in a direction orthogonal to the transport direction D.

  The gap 1205 is provided in the sheet contact direction downstream of the sheet contact position 401 of the feeding path PS3 in the transport direction D, and the sheet powder generated from the transported sheet S enters. The gap 1205 extends in a direction intersecting the transport direction D along the contact surface 1202 with the sheet S at the sheet contact position 401. The gap 1205 communicates the opening 1102 and the outside of the feeding path PS3. The inner wall 1206 of the gap portion 1205 is preferably perpendicular to the conveyance direction D of the sheet S.

  The position corresponding to the position of the supply roller 1004 in the transport direction D of the sheet S is not limited to the case where the opening is provided at a position corresponding to the size of the sheet S, and the sheet powder generated by the supply roller 1004 is collected. May be provided.

<Operation of sheet conveying apparatus>
The operation of the sheet conveying apparatus 400 according to the second embodiment of the present invention will be described in detail.

  The sheet S conveyed from the supply roller 18a is conveyed in the conveyance direction D while rubbing against the opening 1102 located downstream of the sheet contact position 1101.

  Next, the sheet S is conveyed by the supply roller pair 19 and supplied to the feeding roller pair 15. At this time, the sheet S is rubbed against the guide portion G3 to remove the sheet powder.

  The sheet powder removed by the guide part G3 is separated to the back side of the guide part G3 through the opening 1102, and is sucked from the sheet powder suction port 1005 so as not to adhere to the sheet S by its own weight.

  The sheet conveyance speed control process in the present embodiment is the same process as that in FIG. In the sheet conveyance speed control process in the present embodiment, the conveyance speeds of the feeding roller pair 15 and the supply roller pair 19 are set using the table shown in FIG.

  As described above, the present embodiment includes the CPU 101 that controls the feeding roller pair 15 and the supply roller pair 19 so that the conveyed sheet S comes into contact with the predetermined bending region R2 of the feeding path PS3. Further, a gap 1205 is provided in the sheet contact direction downstream of the sheet contact position 1101 of the feeding path PS3 in the sheet contact direction and into which sheet powder generated from the sheet S enters. Thereby, the sheet powder can be removed from the sheet with a simple configuration without complicated control.

  Further, according to the present embodiment, by providing the edge 1203 and the edge 1204 at the edge of the opening 1102, the sheet powder of the sheet S is removed at the edge 1203 and the edge 1204 without hindering the conveyance of the sheet S. Can do.

  Further, according to the present embodiment, the sheet powder in the direction intersecting with the transport direction is provided because the gap 1205 extends in the direction intersecting with the transport direction along the contact surface 1202 with the sheet S. Can be removed.

  In the present embodiment, the guide part G3 and the sheet powder suction port 1005 are separate members, but the guide part G3 and the sheet powder suction port 1005 may be integrated.

  Moreover, in this Embodiment, although sheet | seat powder was attracted | sucked by the suction part 1007, it is not limited to this, You may use the member which adsorb | sucks sheet powder with static electricity.

  Further, in the present embodiment, the inclined portion 1201 is inclined at a predetermined angle. However, the inclined portion 1201 is not necessarily inclined, and may be a curved shape that protrudes downward.

(Embodiment 3)
The configuration of the image forming apparatus according to the third embodiment of the present invention is the same as that shown in FIGS. 1 and 2 except that the sheet conveying apparatus 500 is provided instead of the sheet conveying apparatus 300, and thus the description thereof is omitted.

<Configuration of sheet conveying device>
The configuration of the sheet conveying apparatus 500 according to Embodiment 3 of the present invention will be described in detail with reference to FIG.

  The sheet conveying apparatus 500 is provided in the double-sided printing vicinity area C in FIG. Specifically, the sheet conveying apparatus 500 includes a refeed path PS2, a refeed roller pair 51a, a refeed roller pair 51b, a CPU 101, a motor speed control unit 150, a collection container 1302, and a guide. Part G4.

  The refeed path PS2 that is the conveyance path guides the conveyed sheet S.

  The re-feed roller pair 51a that is the first sheet transport unit is provided on the upstream side in the transport direction D with respect to the bending region R3 of the re-feed path PS2.

  The re-feed roller pair 51b that is the second sheet transport unit is provided on the downstream side in the transport direction D with respect to the bending region R3 of the re-feed path PS2.

  The motor speed control unit 150 controls the rotational speeds of the refeed roller pair 51a and the refeed roller pair 51b according to the control of the CPU 101, so that the sheet S being conveyed is a predetermined bending region of the refeed path PS2. Contact with R3.

  The collection container 1302 is provided below the guide part G4, and accommodates and collects the sheet powder that has been removed from the sheet S by the guide part G4 and dropped. The collection container 1302 is preferably provided so as to be removable so that the collected sheet powder can be cleaned.

  The guide part G4 is provided on the inner peripheral side of the bending region R3 of the refeed path PS2, and removes the sheet powder of the sheet S by rubbing against the surface of the sheet S passing through the refeed path PS2.

<Configuration of guide section>
The configuration of the guide part G4 according to Embodiment 3 of the present invention will be described in detail with reference to FIGS.

  The guide part G4 includes an opening part 1401, an inclined part 1402, a contact surface 1403, an edge 1404, an edge 1405, and a gap part 1406.

  A plurality of openings 1401 are provided in the contact surface 1403 and are provided. The opening 1401 is provided at a position that coincides with the position of the discharge roller pair 41 in the conveyance direction D of the sheet S. The opening 1401 is provided on the downstream side in the conveyance direction D of the sheet S from the sheet contact position 1407 (see FIG. 19) where the sheet S first contacts the sheet S.

  The inclined portion 1402 is inclined in a direction away from the abutting sheet S from the downstream edge 1405 of the gap portion 1406 in the conveying direction D toward the upstream side in the conveying direction D.

  The contact surface 1403 is formed of a resin material that has been subjected to texture processing and has conductivity. The contact surface 1403 is grounded to a sheet metal (not shown) of the image forming apparatus 1000. The contact surface 1403 contacts the surface of the sheet S conveyed through the refeed path PS2.

  The edge 1404 is provided on the upstream edge of the opening 1401 in the conveyance direction D of the sheet S. The edge 1404 is exposed to the contact surface 1403 and extends in the direction intersecting the transport direction D along the contact surface 1403, and is slidable on the surface of the sheet S transported through the refeed path PS2. The edge 1404 is preferably extended in a direction orthogonal to the transport direction D.

  The edge 1405 is provided at the edge of the opening 1401 on the downstream side in the conveyance direction D of the sheet S, and is provided to face the edge 1404. The edge 1405 is exposed to the contact surface 1403 and extends in the direction intersecting the transport direction D along the contact surface 1403, and can rub against the surface of the sheet S transported through the refeed path PS2. The edge 1405 is preferably extended in a direction orthogonal to the transport direction D.

  The gap 1406 is provided in the sheet contact direction downstream of the sheet contact position 1407 of the refeed path PS2 in the sheet contact direction D, and the sheet powder generated from the conveyed sheet S enters. The gap 1406 extends in a direction intersecting the transport direction D along the contact surface 1403 of the sheet contact position 1407 with the sheet S. The gap 1406 communicates the opening 1401 and the outside of the refeed path PS2. The inner wall 1408 of the gap 1406 is preferably perpendicular to the conveyance direction D of the sheet S.

<Operation of sheet conveying apparatus>
The operation of the sheet conveying apparatus 500 according to Embodiment 3 of the present invention will be described in detail.

  The sheet S conveyed from the discharge roller pair 41 is conveyed in the conveyance direction D while sliding on the opening of the guide portion G4.

  Next, the sheet S is conveyed by the refeed roller pair 51a and supplied to the refeed roller pair 51b. At this time, the sheet S is rubbed against the guide portion G4 to remove the sheet powder.

  The sheet powder removed by the guide part G4 is recovered by dropping onto a recovery container 1302 provided below the guide part G4.

  The sheet conveyance speed control process in the present embodiment is the same process as that in FIG.

  In the sheet conveyance speed control process in the present embodiment, the conveyance speeds of the refeed roller pair 51a and the refeed roller pair 51b are set using the table shown in FIG. In the sheet conveying apparatus 500 according to the present embodiment, the guide portion G4 is rubbed against the surface on which an image has already been formed. Therefore, caution is necessary. For example, a transport speed smaller than the transport speed set in the table shown in FIG. 19 may be set as the transport speed of the refeed roller pair 51a and the refeed roller pair 51b.

  In particular, in the ink jet recording system, there are some which have low scratching property depending on the type of ink or sheet, and the act of rubbing the formed image area may cause a problem that the recording density is lowered. Therefore, in the ink jet recording system, it is preferable to control the conveyance speed according to the combination of the ink and the sheet type.

  Thus, in the present embodiment, the CPU 101 that controls the refeed roller pair 15a and the refeed roller pair 15b so that the conveyed sheet S comes into contact with the predetermined bending region R3 of the refeed path PS2. Have. In addition, a gap 1406 is provided in the sheet contact direction on the downstream side in the conveyance direction D of the sheet contact position 1407 of the refeed path PS2 and into which sheet powder generated from the sheet S enters. Thereby, the sheet powder can be removed from the sheet with a simple configuration without complicated control.

  Further, according to the present embodiment, by providing the edge 1404 and the edge 1405 at the edge of the opening 1401, the sheet powder of the sheet S is removed at the edge 1404 and the edge 1405 without hindering the conveyance of the sheet S. Can do.

  In addition, according to the present embodiment, the sheet powder in the direction intersecting the conveyance direction is provided because the gap 1406 extends in the direction intersecting the conveyance direction along the contact surface 1403 with the sheet S. Can be removed.

  In the present embodiment, the inclined portion of the guide portion G4 is inclined at a predetermined angle. However, the inclined portion is not necessarily inclined, and may be a curved shape that protrudes upward.

  The above-described first to third embodiments are merely examples of the present invention, and the embodiments may be appropriately changed without departing from the scope of the present invention.

  Specifically, in Embodiment 1 to Embodiment 3 described above, the guide portion is provided with the opening. However, the present invention is not limited to this. For example, the opening having the release position on the downstream side in the transport direction D is not limited thereto. There may be no guide part. However, in this case, since the sheet powder is scattered in the apparatus, it is preferable to separately provide a suction device or a passage through which the sheet powder passes.

  In the first to third embodiments, when a thin sheet having low rigidity is conveyed, the sheet may not sufficiently contact the opening of the guide portion. Alternatively, a roller may be provided so that the sheet and the opening are in contact with each other.

  In the first to third embodiments, the sheet powder on the surface of the sheet S that contacts the transfer roller 25 is removed. However, the present invention is not limited to this, and the sheet S on the surface opposite to the surface that contacts the transfer roller 25 is removed. Powder may be removed.

  For example, when sheet powder enters the developing unit 60, the sheet powder also enters between the developing roller 72 and a blade (not shown), and the developer cannot be uniformly adhered to the developing roller 72. As a result, the developer image formed on the photosensitive drum 21 is chipped, resulting in image defects such as white spots. Further, there arises a problem of image quality such that the sheet S is soiled when the developer adheres with the sheet powder or dust attached to the pressure roller 32 of the fixing unit 30 as a nucleus. When the developer adheres with sheet powder or dust adhering to an inlet guide (not shown) provided in front of the fixing unit 30 as a core, problems such as jamming occur.

  On the other hand, by removing the sheet powder on the surface opposite to the surface in contact with the transfer roller 25 of the sheet S, it is possible to eliminate the above-described image defects or problems.

  In the first to third embodiments, if sheet powder or dirt adheres to the reading unit 210 of the image reading unit 200, the quality of the reading is deteriorated. Therefore, the present invention is located near the document feeding unit 220. A sheet conveying apparatus may be provided.

  Further, in the first to third embodiments, since the sheet powder or dust adheres to the optical sensor unit that detects the leading edge of the sheet conveyed on the sheet conveyance path, it may cause a false detection. Alternatively, the sheet conveying apparatus of the present invention may be provided on the upstream side in the conveying direction D.

  In the first to third embodiments, the sheet conveying device of the present invention is provided on the upstream side in the conveying direction D from the recovery device for recovering the recording head of the inkjet recording device or the ejection state of the recording head. May be. In the case of an ink jet recording apparatus, when sheet powder or dust adheres to the recording head, the discharge port is blocked, which causes image defects. Further, when sheet powder or dust adheres to the recovery device, a recovery failure may occur. On the other hand, by providing the sheet conveying device of the present invention on the upstream side in the conveying direction D with respect to the recording head or the recovery device, it is possible to avoid the above-described image failure or recovery failure.

  In the first to third embodiments, the sheet conveying device of the present invention may be provided in the sheet conveying path of the finisher that performs the stable process, the punching process, or the bookbinding process. Since the sheet transport path of the finisher often has a complicated shape, sheet powder tends to accumulate on the transport path. In order to remove the sheet powder accumulated on the conveyance path, maintenance by human hands may be required. On the other hand, by providing the sheet conveying apparatus of the present invention in the sheet conveying path of the finisher, the above maintenance can be made unnecessary.

  In the first to third embodiments, the conveyed sheet S is not limited to a paper sheet, and may be a sheet other than paper such as a plastic sheet.

E Document G1 Guide part G2 Guide part G3 Guide part G4 Guide part N1 Transfer nip part N2 Fixing nip part 1 Host PC
2 External Interface 10 Sheet Feeding Unit 11 Feeding Cassette 12 Pickup Roller 13 Separating Roller Pair 15 Feeding Roller Pair 16 Registration Roller Pair 17 Multi-Feed Tray 18a Feeding Rotor 18b Separation Pad 19 Feeding Roller Pair 20 Image Forming Unit 21 Photosensitive Drum 22 Charging roller 23 Laser unit 25 Transfer roller 30 Fixing portion 31 Fixing roller 32 Pressure roller 40 Sheet discharge portion 41 Discharge roller pair 42 Discharge tray 50 Sheet refeeding portion 51a Refeed roller pair 51b Refeed roller pair 51c Re Feed roller pair 60 Developing section 72 Developing roller 100 Image forming section 110 Image signal control section 120 Image reading control section 130 Image forming control section 140 Display section 150 Motor speed control section 200 Image reading section 210 Reading section 220 Document feeding section 300 Sheet conveying device 301 feed roller 302 feeding roller 303 retard roller 304 driven roller 305 collection container 400 sheet conveying device 403 opening 403a opening 500 sheet conveying device 501 inclined portion 502 abutting portion 601 edge 603 edge 604 gap portion 605 inner wall 903 End 1000 Image forming apparatus 1003 Supply roller 1004 Supply roller 1005 Sheet powder suction port 1006 Sheet powder collection path 1007 Suction part 1102 Opening part 1201 Inclined part 1202 Abutting surface 1203 Edge 1204 Edge 1205 Cavity part 1206 Inner wall 1302 Opening container 1401 Opening Portion 1402 Inclined portion 1403 Contact surface 1404 Edge 1405 Edge 1406 Gap portion 1601 Conveying path 1602 Conveying path 1603 Sheet 1604 Conveying roller pair 1605 Opening 1 606 Sheet powder 1607 Non-contact area 1608 Non-contact area

Claims (9)

Conveying means for conveying the sheet;
A conveyance path for guiding a sheet conveyed by the conveyance means;
Control means for controlling the conveying means so that the conveyed sheet comes into contact with a predetermined bending region of the conveying path;
A gap provided in the sheet contact direction on the downstream side of the transport direction of the sheet contact position of the transport path, into which sheet powder generated from the transported sheet enters,
A sheet conveying apparatus comprising: The gap is
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus extends in a direction intersecting with the conveying direction along a contact surface with the sheet. The conveying means is
A first transport unit provided upstream of the bent region in the transport direction and a second transport unit provided downstream of the bent region in the transport direction, the first transport A sheet to be conveyed is brought into contact with the bent region due to a difference in conveyance speed between the second conveyance unit and the second conveyance unit,
The sheet conveying apparatus according to claim 1 or 2. The first transport unit and the second transport unit are:
Conveying the sheet at a speed according to the type of sheet,
The sheet conveying apparatus according to any one of claims 1 to 3, wherein the sheet conveying apparatus is characterized in that: The bending region is
Having an inclined portion that inclines in a direction away from the abutting sheet from the downstream edge of the gap in the conveying direction toward the upstream in the conveying direction;
The sheet conveying apparatus according to claim 4. The gap is
6. The sheet conveying apparatus according to claim 4, wherein the sheet conveying apparatus communicates with the outside. An image forming unit for forming an image on a sheet;
A sheet conveying apparatus for conveying the sheet to form an image on the sheet by the image forming unit;
Have
The sheet conveying apparatus is
Conveying means for conveying the sheet;
A conveyance path for guiding a sheet conveyed by the conveyance means;
Control means for controlling the conveying means so that the conveyed sheet comes into contact with a predetermined bending region of the conveying path;
A gap provided in the abutting direction on the downstream side in the conveying direction of the sheet abutting position of the conveying path, and a gap portion into which sheet powder generated from the conveyed sheet enters;
An image forming apparatus comprising: A sheet feeding unit that feeds the sheet toward the image forming unit;
The sheet conveying apparatus is
Conveying the sheet toward the image forming unit in the sheet feeding unit;
The image forming apparatus according to claim 7. A sheet refeeding unit configured to refeed the sheet toward the image forming unit in order to form an image on the other side of the sheet on which the image is formed on one side by the image forming unit; ,
The sheet conveying apparatus is
Conveying the sheet toward the image forming unit in the sheet re-feeding unit;
The image forming apparatus according to claim 7.