JP2011191641A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus forming an image on a recording medium and maintaining stable image quality by removing, as needed, foreign matters such as paper powder adhering and accumulating on a support part arranged along the conveying passage of the recording medium. <P>SOLUTION: The image forming apparatus includes: a recording medium guide part having a support part arranged along the conveying passage of the recording medium and an endless belt rotationally supported by the support part; and a removal part contacting with the endless belt to remove matters adhering to the outer circumferential surface of the endless belt. At least a part of the outer circumferential surface of the endless belt faces the conveying passage. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus for forming an image on a recording medium.

  2. Description of the Related Art Conventionally, in an image forming apparatus that forms an image on a sheet, there is a problem that an image defect occurs at the time of image formation due to foreign matters such as paper dust that adheres and accumulates on a guide unit provided along a sheet conveyance path . In recent years, when using an image forming apparatus, a wide variety of papers are used, and papers to which a large amount of paper dust adheres such as recycled paper, Chinese paper, and cardboard have come to be used. Due to such diversification of paper, foreign substances such as paper dust adhere and accumulate more than before in the image forming apparatus.

  Foreign matter such as paper dust that adheres and accumulates on the guide portion provided along the paper conveyance path may reattach to the conveyed paper. In such a case, particularly in an electrophotographic image forming apparatus, a part used for image formation such as an image carrier or a charge removal unit is contaminated by foreign matters such as paper dust, and a uniform electric field is formed during transfer or charge removal. Is hindered, causing image noise.

  Regarding the removal of paper dust and the like adhering to the inside of the image forming apparatus, Patent Document 1 discloses an image forming apparatus having a paper dust removing roller provided so as to be in contact with a photosensitive drum.

  Patent Document 2 discloses an image forming apparatus having a conveyance guide to which a conductive sheet is attached. The image forming apparatus described in Patent Document 2 includes a conveyance guide to which the above-described conductive sheet is attached to prevent the transfer paper from being rubbed and frictionally charged. By sticking this sheet, it is possible to suppress to a certain extent that foreign matters such as paper dust adhere to the conveyance guide.

JP 2003-66799 A JP 11-288188 A

  However, the image forming apparatus described in Patent Document 1 relates to the removal of paper dust on the photoconductor, and can remove foreign matters such as paper dust that adhere to and accumulate on guide portions provided along the conveyance path of the recording medium. is not.

  In addition, in a configuration in which a conductive sheet is attached to a conveyance guide as in the image forming apparatus described in Patent Document 2, the conductive sheet deteriorates with use of the image forming apparatus, and thus wavy. A large amount of foreign matter such as paper dust accumulates in the recesses of the deteriorated conductive sheet and adheres. In such a case, foreign matters such as paper dust are easily reattached to the conveyed paper, and the foreign matter such as paper dust that has moved to the transfer unit is charged during image formation, thereby preventing electric field formation and image noise. May occur. In addition, there is also a problem that the paper is waved by the conveyance guide and is not conveyed to the transfer unit along an appropriate conveyance path.

  The present invention has been made in order to solve the above-described problems, and appropriately removes foreign matter such as paper dust that adheres to and accumulates on a guide unit provided along the conveyance path of the recording medium as necessary. It is an object to provide an image forming apparatus that maintains stable image quality by removing the image.

  In order to achieve the above object, an image forming apparatus according to the present invention is an image forming apparatus that forms an image on a recording medium, and includes a support section provided along a transport path of the recording medium and the support section. A recording medium guide unit having an endless belt rotatably supported; and a removing unit that contacts the endless belt and removes deposits attached to the outer peripheral surface of the endless belt. At least a part of the outer peripheral surface is provided so as to face the transport path.

  Furthermore, the image forming apparatus of the present invention is an image forming apparatus that transfers an image on an image carrier to the recording medium, and the recording medium guide portion performs transfer from the image carrier to the recording medium. It may be provided so as to guide the recording medium in the vicinity of the transfer area.

  Furthermore, in the image forming apparatus according to the present invention, the recording medium guide portion may be provided on the upstream side in the passage direction of the recording medium from the transfer area.

  Further, in the image forming apparatus of the present invention, the endless belt is provided such that a surface opposite to a surface onto which the recording medium is transferred contacts the outer peripheral surface of the endless belt when the recording medium is conveyed. Also good.

Further, the image forming apparatus according to the present invention includes a transfer belt as the image carrier, and a transfer area formed on the transfer belt by being pressed against the transfer belt and passing through the transfer area. A transfer roller for transferring an image, a transfer belt cleaning member for removing the deposit from the outer peripheral surface of the transfer belt, a movable movable support portion for supporting the endless belt from the inner peripheral surface side, and the movable support A range from a first position where the endless belt and the transfer roller are in contact with each other to a second position where the endless belt and the transfer roller are separated from each other An image forming apparatus comprising: a movable support unit driving device to be moved; and a bias application unit that applies a bias between the transfer roller and the transfer belt,
In removing the adhering matter adhering to the outer peripheral surface of the endless belt, the movable support unit driving device moves the movable support unit to the first position and rotates the transfer roller to thereby rotate the endless belt. Moving the deposit on the outer peripheral surface of the transfer roller, and the bias applying unit applies a bias to the transfer roller to move the deposit on the transfer roller onto the transfer belt; The deposit on the transfer belt may be removed by the transfer belt cleaning member.

  Furthermore, in the image forming apparatus according to the present invention, the removing unit may be in a roller shape, and may be rotatably provided while being in contact with the endless belt.

  Furthermore, in the image forming apparatus according to the present invention, the removing unit may be a flat blade.

  According to the image forming apparatus of the present invention, it is possible to efficiently remove foreign matters such as paper dust and toner that adhere to and accumulate on the support portion provided along the conveyance path of the recording medium. Can be greatly reduced.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus 1 according to Embodiment 1 of the present invention. FIG. 2 is a schematic perspective view showing an example of a cleaning mechanism that can be provided in the image forming apparatus 1 according to Embodiment 1 of the present invention. FIG. 3 is a schematic diagram illustrating an example of a cleaning mechanism that can be provided in the image forming apparatus 1 according to the first embodiment of the present invention. 6 is a time chart illustrating an example of an operation of a cleaning mechanism that can be provided in the image forming apparatus 1 according to the first embodiment of the present invention. It is a figure which shows the image noise generation rate in the conventional electrophotographic image forming apparatus. It is a figure which shows the image noise generation rate in the image forming apparatus 1 which concerns on Embodiment 1 of this invention. FIG. 3 is a schematic diagram illustrating an example of a cleaning mechanism that can be provided in the image forming apparatus 1 according to the first embodiment of the present invention. It is a schematic block diagram which shows an example of the image forming apparatus 2 which concerns on Embodiment 2 of this invention. It is a schematic perspective view which shows an example of the recording medium guide part (remote position) which can be provided in the image forming apparatus 2 which concerns on Embodiment 2 of this invention. It is a schematic block diagram which shows the cleaning mechanism which can be provided in the image forming apparatus 2 which concerns on Embodiment 2 of this invention. It is a schematic perspective view which shows an example of the recording medium guide part (proximity position) provided in the image forming apparatus 2 which concerns on Embodiment 2 of this invention. It is a schematic block diagram which shows an example of the cleaning mechanism which can be provided in the image forming apparatus 2 which concerns on Embodiment 2 of this invention. 6 is a time chart showing an example of an operation of a cleaning mechanism that can be provided in the image forming apparatus 2 according to Embodiment 2 of the present invention.

The present invention will be described below with reference to embodiments for carrying out the invention.
(1) Embodiment 1
<Image forming apparatus>
FIG. 1 is a schematic configuration diagram showing a tandem color digital image forming apparatus (hereinafter referred to as “image forming apparatus 1”), which is an example of an image forming apparatus according to Embodiment 1 of the present invention. First, an image forming apparatus 1 which is an example of an embodiment for carrying out the present invention will be described with reference to FIG.

  The image forming apparatus 1 is an image forming apparatus that forms a color image, and is of a so-called intermediate transfer type. That is, toner images of different colors formed on a plurality of image carriers are sequentially primary-transferred onto a common intermediate transfer belt to superimpose a single color toner image on the intermediate transfer belt. A color toner image is formed on the recording medium by collectively transferring the color toner image formed thereon onto the recording medium.

  The image forming apparatus 1 includes an intermediate transfer belt 17. In the image forming unit arrangement area provided in the outer peripheral surface area of the intermediate transfer belt 17, yellow is provided along the moving direction of the intermediate transfer belt 17. Four image forming units 30Y, 30M, 30C, and 30K that form a toner image, a magenta toner image, a cyan toner image, and a black toner image are provided to be aligned. Further, a secondary transfer unit 14 is provided at a position downstream of the image forming unit 30K related to black toner, which is an image forming unit at the most downstream position in the moving direction of the intermediate transfer belt 17, and the intermediate transfer belt 17 is provided. An intermediate transfer belt cleaning unit 18T for removing foreign matters such as untransferred toner on the intermediate transfer belt 17 is provided at a position downstream of the secondary transfer unit 14 in the moving direction. Further, an unfixed recording medium transport device 20 is provided at a position downstream of the secondary transfer unit 14 in the recording medium transport direction, and at a position downstream of the unfixed recording medium transport device 20 in the recording medium transport direction. A fixing device 21 is provided. The image forming apparatus 1 includes a control unit 50 that controls each image forming process and a memory 501 that stores data necessary for each image forming process.

  The intermediate transfer belt 17 is stretched around backup members such as the drive roller 17A and the backup rollers 17a, 17b, and 17c. The intermediate transfer belt 17 is conveyed in the direction of arrow T in FIG. 1 when the driving roller 17A is rotated by driving means (not shown) such as a motor.

The intermediate transfer belt 17 is composed of a semiconductive endless belt having a surface resistivity of 1 × 10 ⁴ to 1 × 10 ¹² Ω / □, for example. The surface resistivity of the intermediate transfer belt 17 is 100 V in a normal temperature and humidity environment (temperature 20 ± 1 ° C., humidity 50 ± 2%) using a resistance measuring instrument “Hi-Lester IP” (manufactured by Yuka Denshi). It is a measured value after applying for 10 seconds. The intermediate transfer belt 17 is preferably formed, for example, by adding a conductivity-imparting agent containing carbon black or metal powder to polyimide such as thermosetting polyimide or modified polyimide.

  For example, in the image forming unit 30Y related to a yellow toner image, the image forming unit includes an image carrier 10Y made of a rotating drum-shaped photosensitive member, a charging device 11Y for charging the image carrier 10Y, and an image forming unit. An image forming unit 13Y that performs development with a developer containing yellow toner is provided on the photoreceptor 10Y exposed by the external exposure device 12Y. The charging device 11Y and the image forming unit 13Y are arranged in this order along the rotation direction of the image carrier 10Y with respect to the outer peripheral surface of the image carrier 10Y. Further, an image carrier cleaning means 18Y provided with an image carrier cleaning blade is provided at a position downstream of the primary transfer means 15Y provided at a position downstream of the image forming portion 13Y in the rotation direction of the image carrier 10Y. It has been.

  The image carrier 10Y has a photosensitive layer made of a resin containing an organic photoconductor on the outer peripheral surface of a drum-shaped metal substrate, and is arranged in a state extending in a direction perpendicular to the paper surface in FIG. Yes.

  The charging device 11Y and the exposure device 12Y constitute an electrostatic latent image forming unit that forms an electrostatic latent image on the image carrier 10.

  The charging device 11Y is, for example, a scorotron charger having a grid electrode and a discharge electrode, and charges the surface of the image carrier 10Y.

  The exposure device 12Y is composed of, for example, a laser irradiation device, and exposes the image carrier 10Y by irradiating laser light. The laser light is irradiated, for example, based on an image signal read by a scanner (not shown) and converted into an electrical signal by a CCD sensor (not shown).

  The image forming unit 13Y includes, for example, a developer containing unit and a developing sleeve that contains a magnet and holds the developer and rotates. When an image is formed, the image forming unit 13Y is connected to a voltage applying unit (not shown). A direct current and / or alternating bias voltage is applied.

  The primary transfer unit 15Y includes a primary transfer member and a transfer current supply device connected to the primary transfer member. The primary transfer member can be, for example, the primary transfer roller 151Y, and forms a primary transfer nip portion as a transfer region while being pressed against the surface of the image carrier 10Y via the intermediate transfer belt 17. Arranged.

  The primary transfer unit 15Y is formed on the image carrier 10Y by supplying a primary transfer current to the primary transfer roller 151Y by a transfer current supply device (not shown) including a constant current power source, for example. A so-called contact transfer method in which a yellow toner image is transferred to the intermediate transfer belt 17 can be employed.

  The image carrier cleaning means 18Y has, for example, an image carrier cleaning blade. The image carrier cleaning blade is made of, for example, an elastic body such as urethane rubber, and is provided such that a base end portion thereof is supported by a support member and a front end portion thereof is brought into contact with the surface of the image carrier 10Y. . The direction extending from the base end side of the image carrier cleaning blade can be a so-called counter direction, which is the direction opposite to the moving direction due to the rotation of the image carrier 10Y at the contact portion.

  The image forming unit is configured such that, for example, the image carrier 10Y, the charging device 11Y, the image forming unit 13Y, and the image carrier cleaning means 18Y are integrally supported by a frame (not shown) and are detachable. be able to.

  Each of the other image forming units 30M, 30C, and 30K has the same configuration as that of the image forming unit 30Y related to the yellow toner image except that magenta toner, cyan toner, and black toner are used instead of yellow toner. Yes.

  In each of the primary transfer units 15M, 15C, and 15K, the primary transfer current is supplied and formed on the image carriers 10Y, 10M, 10C, and 10K, similarly to the image forming unit 30Y related to the yellow toner image. Each of the toner images is subjected to primary transfer onto the intermediate transfer belt 17 that circulates in the direction of arrow T at a predetermined timing, thereby forming a multicolor toner image in which the single color toner images are superimposed on the intermediate transfer belt 17. Is done.

  The secondary transfer unit 14 presses the drive roller 17A via the intermediate transfer belt 17, the drive roller 17A disposed on the inner peripheral surface side of the intermediate transfer belt 17 and the intermediate transfer belt 17 as a secondary transfer region. A secondary transfer roller 141 that forms a transfer nip portion, and a transfer bias application unit 142 connected to the secondary transfer roller 141 are configured. The secondary transfer roller can be, for example, a semiconductive rubber roller.

  The secondary transfer unit 14 conveys the color toner image formed on the intermediate transfer belt 17 by applying a transfer voltage from the transfer bias applying unit 142 between the secondary transfer roller 141 and the driving roller 17A. This is a so-called contact transfer method in which secondary transfer is performed on the recording medium P.

  Here, in the secondary transfer unit 14, a secondary transfer nip portion as a transfer region is formed by the secondary transfer roller 141 and the intermediate transfer belt 17 in contact with the driving roller 17A. The secondary transfer nip portion is a nip where secondary transfer is performed, and is, for example, a portion where a nip is formed by an intermediate transfer belt and a transfer member such as a secondary transfer roller.

  The secondary transfer unit 14 includes, for example, an intermediate transfer belt 17 and a driving roller 17A that is pressed against the secondary transfer roller 141 via the intermediate transfer belt 17 to form a secondary transfer nip portion as a secondary transfer region. The secondary transfer roller 141 can be configured by a removable intermediate transfer belt unit having backup members such as the backup rollers 17a, 17b and 17c.

  Although the details will be described later, the recording medium P is conveyed or trajected by a recording medium guide unit 161 having a guide unit that guides the recording medium P that is unloaded from a paper feeding device (not shown) and conveyed through a conveyance path. It is conveyed to the secondary transfer nip while being corrected. The recording medium guide unit 161 constitutes a conveyance path.

  The toner image is secondarily transferred onto the recording medium P conveyed to the secondary transfer nip portion, and the recording medium P on which the toner image is secondarily transferred is, for example, an unfixed recording medium conveyance as a recording medium guide portion. It is conveyed to the fixing device 21 by the device 20.

  The unfixed recording medium conveyance device 20 includes, for example, a conveyance roller 201 and a conveyance belt 202, and conveys the recording medium P by rotating the conveyance belt 202 by the conveyance roller 201. Further, for example, by providing a fan (not shown), the recording medium P may be sucked onto the transport belt and transported.

  The fixing device 21 includes, for example, a heating roller 211, a pressure roller 212, a fixing roller 213, and a fixing belt 214, and pressurizes and heats the toner image transferred onto the recording medium P to fix it. The recording medium P that has passed through the fixing device 21 is carried out of the image forming apparatus along the conveyance path.

  Further, an intermediate transfer belt cleaning blade 181 for removing untransferred toner on the intermediate transfer belt 17 and an intermediate transfer belt cleaning blade 181 are disposed downstream of the secondary transfer unit 14 in the moving direction of the intermediate transfer belt 17. An intermediate transfer belt cleaning unit 18T provided with a collection unit 182 that collects the removed untransferred toner and the like is provided.

The intermediate transfer belt cleaning blade 181 has a flat plate shape, and is made of, for example, an elastic material such as urethane rubber. It is provided so that it abuts. The direction extending from the base end side of the intermediate transfer belt cleaning blade 181 can be a so-called counter direction, which is a direction opposite to the moving direction due to the rotation of the intermediate transfer belt 17 at the contact portion.
<Recording medium guide section and cleaning mechanism>
Next, an example of the cleaning mechanism 16 including the recording medium guide unit 161 and the recording medium guide unit 161, which are characteristic parts of the image forming apparatus 1, will be described with reference to FIGS. 1 to 5.

  First, the outline of the cleaning mechanism 16 will be described with reference to FIG.

  As shown in FIG. 2, the cleaning mechanism 16 is removed by the recording medium guide unit 161 that guides the conveyance of the recording medium, the removing unit 163 that removes foreign matter attached to the recording medium guide unit 161, and the removing unit 163. The collecting unit 164 collects foreign matter, and is provided along the conveyance path of the recording medium P.

  The recording medium guide portion 161 includes an endless belt 1612, a support portion 1611 that supports the endless belt 1612 from the inner peripheral surface side, and a tension member 1613 that presses the endless belt 1612 from the inner peripheral surface side. it can.

  The endless belt 1612 is wound around the support portion 1611 and the tension member 1613 and is disposed so as to be slidable with respect to the support portion 1611 and the tension member 1623.

  For example, in FIG. 2, the inner peripheral surface of the endless belt 1612 slides relative to the support portion 1611 and the tension member 1623, and the outer peripheral surface of the endless belt 1612 facing the conveyance path of the recording medium P, that is, the endless belt. The endless belt 1612 is arranged so that the portion facing the conveyance path 1612 moves in the conveyance direction of the recording medium P.

  Further, for example, the endless belt 1612 may be arranged so as to be slidable with respect to a plurality of support portions 1611 provided in the recording medium conveyance direction. A part of the outer peripheral surface facing the conveyance path of the endless belt 1612 may be covered with another guide or the like.

  Here, the length of the endless belt 1612 in the belt width direction can be greater than or equal to the sheet passing width in the recording medium conveyance path. Although details will be described later, when the recording medium guide portion 161 having such an endless belt 1612 is used in a cleaning mechanism, foreign matters such as paper dust can be cleaned without any leakage in the sheet passing width direction of the recording medium conveyance path.

  The endless belt 1612 is composed of a composite layer film in which PTFE, PFA, FEP is coated as a release layer on a film surface of polyamideimide, PEEK, PES, PPS or the like, for example. The thickness of the sliding sheet is preferably 50 μm to 200 μm. The rubbing sheet in the above thickness range can obtain more sufficient durability against wear caused by sliding on the support portion 1611 and the tension member 1623. The endless belt 1612 may have a base layer made of a resin or the like and a surface layer made of a rubbing sheet.

  The support portion 1611 is made of sheet metal, for example. The support portion 1611 supports the endless belt 1612 so that the end on the upstream side and the end on the downstream side in the conveyance direction of the recording medium have a certain curvature, and the endless belt 1612 can slide. As the support portion 1611, a guide portion that guides the conveyance of the recording medium P can be used. When a guide portion provided along the conveyance path of the recording medium P is used as the support portion 1611, the conveyance of the recording medium P is guided by the support portion 1611 and the endless belt 1612 supported by the support portion 1611. The

  The tension member 1613 has a curvature surface having a certain curvature, and is provided so that the curvature surface abuts on the inner peripheral surface side of the endless belt 1612, and a certain amount (2 to 20 N / m) of tension. Is provided to endless belt 1612.

  The removal part 163 has a roller shape with a surface made of a foam. Further, for example, the removing unit 163 can be a columnar body having a polygonal bottom surface, and can have a rotatable shape by having a rotation axis in the longitudinal direction. Moreover, the removal part 163 may have a bristle on the surface.

  The collection unit 164 includes a collection container 1641 and a conveyance member (not shown) provided in the collection container 1641. The foreign matter in the collection container 1641 can be discharged to the outside of the image forming apparatus by being transported to a waste toner box or the like by the transport member.

  Next, the configuration and operation of the cleaning mechanism 16 will be described with reference to FIG.

  FIG. 3 shows the cleaning mechanism 16 shown in FIG. 2 provided with a pre-transfer lower guide portion 1611 a as a support portion 1611. The pre-transfer lower guide portion 1611a is a transfer guide portion that guides the conveyance of the recording medium P conveyed near the transfer nip portion through the recording medium conveyance path. The cleaning mechanism 16 shown in FIG. 3 can clean foreign matters such as paper dust that adhere to and accumulate on the pre-transfer lower guide portion 1611a.

  The pre-transfer lower guide portion 1611a is a transfer guide portion provided in the vicinity of the secondary transfer nip portion, and the surface of the transfer guide portion facing the recording medium conveyance path transfers the image of the recording medium P before the secondary transfer. A transfer guide portion provided to face the surface opposite to the surface to be formed. The pre-transfer lower guide portion 1611a corrects the transport angle when the recording medium P is transported to the secondary transfer nip portion so as to be a specific transport angle corresponding to the type of the recording medium P. That is, the pre-transfer lower guide portion 1611a is upstream of the recording medium conveyance direction (left side in FIG. 3) by the power from the pre-transfer lower guide portion driving means (not shown) with the pre-transfer lower guide portion fixing portion A as a fulcrum. And the conveyance angle of the recording medium P is corrected by rotating to the downstream side (right side in FIG. 3). The pre-transfer lower guide part driving means drives the pre-transfer lower guide part 1611a with the power of a motor, for example. Further, the pre-transfer lower guide unit driving unit is controlled by the control unit 50 based on information stored in the memory 501, for example, information such as basis weight of the recording medium P. It should be noted that the surface of the lower guide portion 1611a before transfer facing the recording medium conveyance path is provided along the conveyance path because the surface opposite to the surface onto which the image of the recording medium P is transferred contacts and rubs. Compared with the guides of the above, especially paper dust is more likely to adhere and accumulate.

  When the recording medium guide unit 161 is configured using such a pre-transfer lower guide portion 1611a as the support portion 1611, foreign matters such as paper dust adhere to the outer peripheral surface of the endless belt 1612 supported by the pre-transfer lower guide portion 1611a. . The paper dust adhering to the recording medium P is fixed to the outer peripheral surface of the endless belt 1612 by physical force when the recording medium P comes into contact with the recording medium guide portion 161 and the trajectory is corrected. Accordingly, it adheres and accumulates mainly on the outer peripheral surface of the endless belt 1612 that is exposed toward the conveyance path of the recording medium P.

  The cleaning operation of the cleaning mechanism 16 shown in FIG. 3 will be described below.

  As described above, foreign matter such as paper dust attached to the endless belt 1612 adheres and accumulates by receiving pressure when the recording medium P is conveyed or trajectory-corrected by the recording medium guide portion 161. In cleaning, first, the removing unit 163 is rotationally driven at a constant speed (5 to 100 rpm) counterclockwise in FIG. 3 by a motor or the like (not shown). At this time, the endless belt 1612 that is in contact with the removal portion 163 on the outer peripheral surface is rotated at a constant speed (1 to 100 rpm) clockwise in FIG. 2 by the rotation of the removal portion 163. That is, the endless belt 1612 rotates following the clockwise direction in FIG.

  The removing unit 163 drives the endless belt 1612 to rotate, and rubs the outer peripheral surface of the endless belt 1612 due to a speed difference and a frictional resistance difference generated at a contact portion between the removing unit 163 and the outer peripheral surface of the endless belt 1612. .

  At this time, foreign matters such as paper dust attached to the endless belt 1612 are scraped off by the removing unit 163. The scraped foreign matter such as paper dust is carried to the collection unit 164 as the removal unit 163 rotates, and is collected in the collection container 1641 of the collection unit 164. Foreign matter such as paper dust collected in the collection container 1641 is discharged out of the cleaning mechanism 16 by a conveying member (not shown) in the collection container 1641.

  The above-described cleaning operation is performed by the control unit 50 using the image forming apparatus 1 in the usage state (number of output sheets, image forming unit driving time, image carrier driving time, intermediate transfer belt driving time, printing rate, etc. Control based on information on at least one).

  Here, FIG. 4 is a schematic time chart showing an example of the cleaning process controlled by the control unit 50 for the cleaning mechanism 16 shown in FIG.

  The cleaning mechanism 16 starts a cleaning operation after a certain period of time after the image forming apparatus 1 is turned on. Thereafter, the cleaning mechanism 16 stops its operation when a print job is started and the recording medium P is guided by the recording medium guide unit 161. More specifically, before the conveyed recording medium P is corrected by the recording medium guide portion 161 so that the recording medium P has a fixed entry angle when entering the secondary transfer nip portion, that is, the recording medium P is the recording medium guide. Before contacting the part 161, the rotational drive of the removal part 163 stops. When the removal unit 163 is stopped, the movement of the endless belt 1612 that has been driven and stopped is stopped.

  After the movement of the endless belt 1612 stops, the recording medium P comes into contact with the recording medium guide portion 161, and the conveyance path of the recording medium P is corrected. Then, the downstream end in the transport direction of the recording medium P whose trajectory has been corrected enters the secondary transfer nip portion, and after the secondary transfer is performed, the rotational driving of the removing portion 163 is resumed. When the rotational driving of the removing unit 163 is resumed, the endless belt 1612 rotates again, and the cleaning mechanism 16 is activated again.

  The effects of the image forming apparatus 1 provided with the cleaning mechanism 16 configured and acting as described above will be described with reference to FIGS.

  FIG. 5 shows an image noise generation rate of an image forming apparatus having a configuration in which a conductive sheet is attached to the pre-transfer lower guide portion 1611a, which is a conventionally known method. On the other hand, FIG. 6 shows the image noise occurrence rate of the image forming apparatus 1 provided with the cleaning mechanism 16 of the present invention.

As shown in FIGS. 5 and 6, according to the image forming apparatus 1 provided with the cleaning mechanism 16 described above, foreign matters such as paper dust and toner that adhere to and accumulate on the paper passing surface of the lower guide portion 1611a before transfer are efficiently used. Therefore, the occurrence of image noise can be greatly reduced. In particular, in addition to the case where plain paper (for example, a basis weight of 60 to 90 g / m ² ) is used, super thick paper (for example, a basis weight of 350 to 420 g / m ² ), cardboard ( For example, when the basis weight is 250 to 350 g / m ² ) and Chinese paper and recycled paper are used in many cases, the image noise is significantly reduced.

  As shown in FIG. 7, the cleaning mechanism 16 may be provided on the pre-transfer upper guide portion 1611b side. The pre-transfer upper guide portion 1611b is a transfer guide portion provided in the vicinity of the secondary transfer nip portion, and the surface of the transfer guide portion facing the recording medium P conveyance path is the recording medium P before the secondary transfer. It is a transfer guide part provided so as to face the surface to be transferred. Here, a pre-transfer upper guide portion 1611b is provided as the support portion 1611. According to the cleaning mechanism 16 having such a configuration, it is possible to remove foreign matters that are attached to the pre-transfer upper guide portion 1611b and are generated due to powder dust such as paper dust and toner generated when the recording medium P is conveyed. Therefore, according to the image forming apparatus 1 provided with such a cleaning mechanism 16, image noise can be significantly reduced.

  Further, the cleaning mechanism 16 is configured with a post-transfer guide portion 1611c provided in the vicinity of the secondary transfer nip portion downstream of the secondary transfer nip portion in the recording medium conveyance direction as a support portion 1611 for guiding the conveyance of the recording medium after transfer. You can also According to the cleaning mechanism 16 having such a configuration, for example, when a neutralizing unit that neutralizes the residual potential of the intermediate transfer belt is provided on the downstream side in the conveyance direction of the recording medium from the secondary transfer nip, It is possible to prevent the charge removal portion from being contaminated by foreign matters such as the above. More specifically, by removing the paper dust adhering to the guide portion provided in the vicinity of the secondary transfer nip portion on the downstream side in the recording medium conveyance direction from the secondary transfer nip portion, such paper dust becomes a recording medium. It is possible to prevent the static eliminator from being polluted by flying up as powdered smoke as it is conveyed. According to the image forming apparatus 1 provided with the cleaning mechanism 16 having such a configuration, it is possible to prevent image noise due to insufficient neutralization of the residual potential of the intermediate transfer belt.

  Further, the cleaning mechanism 16 may be provided in the conveyance path of the recording medium P other than the vicinity of the secondary transfer nip portion. Here, a guide portion that guides the conveyance of the recording medium is provided as the support portion 1611. According to the cleaning mechanism 16 having such a configuration, foreign matters such as paper dust adhered and deposited on the guide portion rise as powder smoke along with the conveyance of the recording medium P, and are used for image formation of the image carrier or the charge removal portion. Since it is possible to prevent the portion from being contaminated, image noise can be reduced.

When a guide portion is provided as the support portion 1611 of the cleaning mechanism 16 on the upstream side of the conveyance path from the secondary transfer nip portion, foreign matters such as paper dust are collected on the upstream side of the conveyance path. Further, it is possible to prevent such foreign matter from reattaching to the recording medium P that has been conveyed and moving to the vicinity of the secondary transfer nip portion. Accordingly, it is possible to reduce foreign matters such as paper dust that adhere to and accumulate on the guide portion in the vicinity of the secondary transfer nip portion.
(2) Embodiment 2
Differences from the image forming apparatus 1 in the example of the image forming apparatus (hereinafter referred to as “image forming apparatus 2”) according to the second embodiment shown in FIG.
<Image forming apparatus 2>
First, referring to FIGS. 9 to 12, the recording medium guide unit 162 and the cleaning mechanism 16 which are characteristic parts in the image forming apparatus 2 are different from the recording medium guide unit 162 and the cleaning mechanism 16 in the image forming apparatus 1. Will be explained. The image forming apparatus 2 mainly has a feature that foreign matters such as paper dust conveyed from the cleaning mechanism 16 are collected by the intermediate transfer belt cleaning unit 18T through the secondary transfer roller 141 and the intermediate transfer belt 17. Different from the image forming apparatus 1.

  The cleaning mechanism 16 includes an endless belt 1622, a support portion 1621 that supports the endless belt 1622 from the inner peripheral surface side, and a recording medium guide portion 162 that includes a movable support portion 1623 that presses the endless belt 1622 from the inner peripheral surface side. It is comprised from a support part drive device (not shown), for example, can be set as a structure as shown in FIG.9 and FIG.10.

  Here, the movable support unit driving device includes a motor driven by a control signal from the control unit 50, and a mechanism for converting the rotational power of the motor into parallel movement of the movable unit, such as a rack and pinion, a cam, Or it has mechanisms, such as a crank.

  In the recording medium guide portion 162, the support portion 1621 is a pre-transfer lower guide portion 1621a. The pre-transfer lower guide portion 1621a can have the same configuration as the pre-transfer lower guide portion 1611a.

  The movable support portion 1623 has a fixed portion 1623b and a movable portion 1623a. The movable support portion 1623 is provided in parallel to the support portion 1621 so that the endless belt 1622 is stretched with a constant tension (2 to 20 N / m). Here, “parallel” is a concept including substantially parallel.

  The movable portion 1623a has a cylindrical shape with an annular cross section, and the outer peripheral surface has a constant curvature. In addition, a fixed portion 1623b is inserted into a hole formed in the central portion in the short direction of the movable portion 1623a.

  The movable portion 1623a is disposed so that the outer peripheral surface is in contact with the inner peripheral surface side of the endless belt 1622, and a proximity position close to the secondary transfer roller 141 by power from a motor constituting the movable support unit driving device. It is provided so as to be movable between a remote position and a position farther from the secondary transfer roller 141 than the close position. Note that the movable range of the movable portion 1623a is restricted by the fixed portion 1623b inserted into the movable portion 1623a.

  The movable portion 1623a located at the close position is in a state where the endless belt 1622 and the secondary transfer roller 141 are in contact with each other, and the movable portion 1623a located at a remote position is in a state where the endless belt 1622 and the secondary transfer roller 141 are separated from each other. And

  The endless belt 1622 is wound around the support portion 1621 and the movable support portion 1623 and is disposed so as to be slidable with respect to the support portion 1621 and the movable support portion 1623.

  As described above, the paper dust adhering to the recording medium P is fixed to the outer peripheral surface of the endless belt 1622 by physical force when the recording medium P comes into contact with the recording medium guide portion 162 and the trajectory is corrected. . On the other hand, the paper dust on the outer peripheral surface of the endless belt 1622 is adhered and deposited also by electrostatic attraction. This is because paper dust is mainly charged with a positive charge.

  Next, the operation of the cleaning mechanism 16 will be described with reference to FIGS. 9, 10, 11, 12 and 13. It should be noted that the cleaning operation is performed by the control unit 50 at least of the usage state of the image forming apparatus 2 (number of output sheets, driving time of the image forming unit, driving time of the image carrier, driving time of the intermediate transfer belt 17 and printing rate). Based on the information on (1), it is controlled to operate during non-image formation.

  Here, FIG. 13 is a schematic flowchart illustrating an example of a cleaning process controlled by the control unit 50 for the cleaning mechanism 16 of the image forming apparatus 2.

  9 and 10, the outer peripheral surface of the endless belt 1622 is separated from the outer peripheral surface of the secondary transfer roller 141 because the movable portion 1623a is located at a remote position. The movable portion 1623a is moved from the remote position (FIGS. 9 and 10) to the close position (FIGS. 11 and 12) by the driving force of the movable support driving device that receives the drive command from the control unit 50. When the movable portion 1623a moves to the close position, the endless belt 1622 is stretched so that the outer peripheral surface on the downstream side in the recording medium conveyance direction projects. As shown in FIG. 12, the endless belt 1622 is stretched so that the outer peripheral surface of the endless belt 1622 on the downstream side in the conveyance direction of the recording medium protrudes, so that the endless belt 1622 applies a constant pressure (2 to 2) to the secondary transfer roller 141. 20 N / m).

  The paper dust on the outer peripheral surface of the endless belt 1622 is rotated by the endless belt 1622 pressed against the secondary transfer roller 141 in a direction opposite to the secondary transfer roller 141 (counterclockwise in FIG. 12). The next transfer roller 141 and the endless belt 1622 are conveyed to an abutting portion where they abut. At this time, the portion of the endless belt 1622 facing the conveyance path moves in the direction opposite to the conveyance direction of the recording medium P.

  Foreign matter such as paper dust conveyed to the contact portion is caused by the speed difference, frictional resistance difference, and electrostatic attraction generated between the secondary transfer roller 141 and the endless belt 1622 at the contact portion. Move on the outer surface. The paper dust that has moved onto the outer peripheral surface of the secondary transfer roller 141 moves to the secondary transfer nip portion when the secondary transfer roller 141 is rotationally driven. The paper powder that has moved to the secondary transfer nip is applied to the secondary transfer roller 141 by the transfer bias applying unit 142, thereby reducing the adhesion of the paper powder and moving it onto the intermediate transfer belt 17. It becomes possible. Note that the paper dust moved onto the intermediate transfer belt 17 is attached by electrostatic attraction.

  After the paper dust moves on the intermediate transfer belt 17, the intermediate transfer belt 17 is driven to rotate so that the paper dust conveyed to the intermediate transfer belt cleaning means 18T is brought into pressure contact with the intermediate transfer belt 17. Scraped by 181. The paper dust scraped off by the intermediate transfer belt cleaning blade 181 is collected by the collection unit 182 of the intermediate transfer belt cleaning unit 18T.

  According to the image forming apparatus 2 configured as described above, the intermediate transfer belt cleaning unit 18T serves as the removing unit 163 that scrapes off foreign matters such as paper dust and the collecting unit 164 that collects scraped foreign matters. In addition to the effects of the image forming apparatus 1 described above, low cost and space saving of the image forming apparatus can be realized.

  As described above, according to the image forming apparatus shown in FIGS. 1 and 8, the cleaning mechanism 16 configured as described above is provided in the recording medium conveyance path, thereby causing a foreign matter such as paper dust as a cause. Therefore, it is possible to completely prevent image noise during transfer.

  The image forming apparatus according to the embodiment for carrying out the present invention is merely an example, and does not limit the present invention. Accordingly, the present invention can be variously improved and modified without departing from the scope of the invention. The present invention can be applied not only to a tandem color image forming apparatus but also to a monochrome / color copying machine, a printer, a FAX, and a complex machine thereof. For example, the cleaning mechanism 16 may be provided in a recording medium storage device that stores a recording medium before feeding that can be attached to and detached from the image forming apparatus main body. Further, for example, the cleaning mechanism 16 can be provided in an image forming apparatus that can use cloth or the like as a recording medium. In such an image forming apparatus, foreign matters such as lint and dust that adhere to and accumulate on the recording medium conveyance path can be removed.

10Y, 10M, 10C, 10K Image carrier 11Y, 11M, 11C, 11K Charging device 12Y, 12M, 12C, 12K Exposure device 13Y, 13M, 13C, 13K Image forming unit 14 Secondary transfer unit 141 Secondary transfer roller 142 Transfer Bias application unit 15Y, 15M, 15C, 15K Primary transfer means 151Y, 151M, 151C, 151K Primary transfer roller 16 Cleaning mechanism 161 Recording medium guide unit 1611 Support unit 1611a Lower transfer guide unit 1611b Before transfer upper guide unit 1611c Transfer Rear guide section 1612 Endless belt 1613 Tension member 162 Recording medium guide section 1621 Support section 1621a Lower transfer guide section 1622 Endless belt 1623 Movable support section 1623a Movable section 1623b Fixed section 163 Removal section 164 Collection section 1641 times Container 17 Intermediate transfer belt 17A Drive rollers 17a, 17b, 17c Backup rollers 18Y, 18M, 18C, 18K Image carrier cleaning means 18T Intermediate transfer belt cleaning means 181 Intermediate transfer belt cleaning blade 182 Collection unit 20 Unfixed recording medium transport device 201 Conveying roller 202 Conveying belt 21 Fixing device 211 Heating roller 212 Pressure roller 213 Fixing roller 214 Fixing belt 30Y, 30M, 30C, 30K Image forming unit 50 Control unit 501 Memory A Lower guide fixing portion before transfer

Claims (7)

An image forming apparatus for forming an image on a recording medium, comprising: a support provided along a conveyance path of the recording medium; and a recording medium guide having an endless belt rotatably supported by the support A removal portion that contacts the endless belt and removes deposits adhering to the outer peripheral surface of the endless belt, and that at least a part of the outer peripheral surface of the endless belt faces the transport path. An image forming apparatus. An image forming apparatus for transferring an image on an image carrier to the recording medium, wherein the recording medium guide unit is configured to transfer the recording medium in a vicinity of a transfer region where transfer from the image carrier to the recording medium is performed. The image forming apparatus according to claim 1, wherein the image forming apparatus is provided so as to guide. The image forming apparatus according to claim 2, wherein the recording medium guide portion is provided upstream of the transfer area in the passage direction of the recording medium. 4. The endless belt is provided so that a surface opposite to a surface onto which the recording medium is transferred contacts the outer peripheral surface of the endless belt when the recording medium is transported. The image forming apparatus described A transfer belt as the image carrier, a transfer roller that forms the transfer area by being pressed against the transfer belt, and transfers the image on the transfer belt to the recording medium passing through the transfer area; and the transfer A transfer belt cleaning member that removes the deposits from the outer peripheral surface of the belt, a movable movable support portion that supports the endless belt from the inner peripheral surface side, the movable support portion, the endless belt, and the transfer roller A movable support unit drive device that moves in a range from a first position that is a position in which the endless belt is in contact with a second position that is a position in which the endless belt and the transfer roller are separated from each other; An image forming apparatus having a bias applying unit that applies a bias between the transfer roller and the transfer belt,
In removing the adhering matter adhering to the outer peripheral surface of the endless belt, the movable support unit driving device moves the movable support unit to the first position and rotates the transfer roller to thereby rotate the endless belt. Moving the deposit on the outer peripheral surface of the transfer roller, and the bias applying unit applies a bias to the transfer roller to move the deposit on the transfer roller onto the transfer belt; 5. The image forming apparatus according to claim 2, wherein the deposit on the transfer belt is removed by the transfer belt cleaning member. The image forming apparatus according to claim 1, wherein the removing unit has a roller shape and is provided to be rotatable while being in contact with the endless belt. The image forming apparatus according to claim 1, wherein the removing unit is a flat blade.

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