JP5303252B2 - Cleaning device and image forming apparatus equipped with the same - Google Patents

Description

  The present invention relates to a cleaning device for an intermediate transfer body that transfers toner images onto paper and then removes and removes deposits such as toner remaining on the surface of the intermediate transfer body. The present invention also relates to an image forming apparatus typified by a copying machine or a printer equipped with this cleaning device.

  In an electrophotographic image forming apparatus such as a copying machine or a printer, a photosensitive drum is widely used as an image carrier. A general image forming operation using the photosensitive drum is as follows. The surface of the photosensitive drum is uniformly charged with a predetermined potential by a charging device, and the potential is partially attenuated by irradiating the LED light of the exposure device, etc., to form an electrostatic latent image of the original image. Is done. The electrostatic latent image is developed with a developing device, whereby a toner image is formed on the surface of the photosensitive drum. This toner image is transferred to the sheet when the sheet is inserted into a transfer region formed by bringing the photosensitive drum and the transfer member into contact with each other or close to each other.

  The image forming apparatus includes a type in which a toner image is directly transferred from a photosensitive drum, which is an image carrier, onto a sheet, and a toner image is once carried on an intermediate transfer body and then transferred from the intermediate transfer body to a sheet. There is also. The intermediate transfer member is often found in an image forming apparatus for color printing such as a so-called tandem type image forming apparatus in which image forming units corresponding to a plurality of colors of toner are arranged in a line.

  In the image forming apparatus as described above, after a toner image is transferred to a sheet, a small amount of toner may remain on the surface of the intermediate transfer member without being transferred to the sheet. In addition, paper dust scattered from the paper may adhere to the surface of the intermediate transfer member. Deposits such as residual toner and paper dust adhering to the surface of the intermediate transfer member obstruct the next new image formation, and therefore need to be cleaned.

2. Description of the Related Art Some cleaning devices that clean deposits on the surface of an image carrier such as an intermediate transfer member use a brush roller to clean the deposits using a brush roller. Examples of such cleaning devices can be found in US Pat. The cleaning devices described in Patent Documents 1 and 2 clean the deposits on the surface of the photosensitive drum as an image carrier, and the cleaning is performed by a brush roller (fur brush).
Japanese Laid-Open Patent Publication No. 4-296922 (page 2, FIG. 1) JP-A-10-282854 (5th page, FIG. 3)

  In the cleaning apparatus described in Patent Documents 1 and 2, the surface of the photosensitive drum, which is an image carrier, is scraped off by rotating a brush roller having an axial length corresponding to the paper width. Deposits such as toner can be removed. However, since the intermediate transfer member, particularly the intermediate transfer belt made endless, may meander during rotation, toner may adhere outside the effective image area corresponding to the paper width.

  In addition, since the portion outside the effective image area of the intermediate transfer belt is rarely used for the primary transfer and secondary transfer of the toner image, the toner moved or scattered from the photosensitive drum or the developing device to this portion. Is easy to accumulate. The toner accumulated on the surface of the intermediate transfer belt in this way may drop or scatter on the paper in the image forming unit or the paper feeding unit, and may adversely affect image formation.

  Furthermore, the outer side of the effective image area of the intermediate transfer belt, that is, both ends in the paper width direction are easily warped and drooped due to the manufacturing method and process of the belt itself, and a belt meandering mechanism is provided. The displacement may be significant. In this way, since both ends of the intermediate transfer belt in the sheet width direction may be undulated, the cleaning roller needs to be brought into stable and effective contact with the surface of the intermediate transfer belt.

  The present invention has been made in view of the above points, and in a cleaning apparatus including a cleaning roller for removing deposits on the surface of the intermediate transfer member, the present invention can reliably apply not only to the effective image region on the surface of the intermediate transfer member but also to the entire region. It is an object of the present invention to provide a cleaning device that can be brought into contact with a cleaning roller and can maintain a suitable cleaning performance. It is another object of the present invention to provide an image forming apparatus equipped with such a cleaning apparatus and capable of performing high-quality image formation.

  In order to solve the above-described problems, the present invention provides a cleaning device that includes a cleaning roller that rotates in contact with an intermediate transfer member and removes deposits on the surface of the intermediate transfer member. The brush roller has a length in the axial direction longer than that of the image region, and a large-diameter portion having a diameter larger than that of the portion corresponding to the effective image region is provided outside the effective image region.

  In the present invention, the cleaning device is mounted on the image forming apparatus.

  In the image forming apparatus having the above-described configuration, a counter roller facing the cleaning roller is provided across the intermediate transfer member, and the counter roller has an axial length corresponding to the effective image area of the intermediate transfer member. I decided to have it.

  According to the configuration of the present invention, in the cleaning device including a cleaning roller that rotates in contact with the intermediate transfer member and removes deposits on the surface thereof, the cleaning roller is longer than the effective image area of the intermediate transfer member. The brush roller having an axial length is provided with a large-diameter portion having a diameter larger than the portion corresponding to the effective image area at a position outside the effective image area. Further, it is possible to make contact with a portion outside the effective image area of the intermediate transfer member, and even when there is a undulation in the outside portion, it is possible to make the contact stably by the action of the large diameter portion. In this way, it is possible to provide a cleaning device that can reliably bring the cleaning roller into contact with not only the effective image area on the surface of the intermediate transfer member but also the entire area thereof and can maintain a suitable cleaning performance. .

  In the present invention, since the cleaning device is mounted on the image forming apparatus, the cleaning roller is surely brought into contact with not only the effective image area on the surface of the intermediate transfer member but also the entire area thereof to maintain a suitable cleaning performance. Thus, an image forming apparatus capable of performing high-quality image formation can be obtained.

  The image forming apparatus having the above-described configuration includes a counter roller facing the cleaning roller across the intermediate transfer member, and the counter roller has an axial length corresponding to the effective image area of the intermediate transfer member. Since there is a meandering prevention mechanism for the intermediate transfer member, when there is no opposing roller up to the region outside the effective image region of the intermediate transfer member, even if the undulation in the outer region is severe, the large diameter The cleaning roller can be effectively stabilized and brought into contact with the surface of the intermediate transfer belt by the function of the portion. Therefore, it is possible to provide an image forming apparatus capable of maintaining a suitable cleaning performance while preventing meandering of the intermediate transfer member, and capable of performing higher quality image formation.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  First, an image output operation of an image forming apparatus equipped with a cleaning device according to an embodiment of the present invention will be described while explaining the outline of the structure with reference to FIGS. 1 and 2. FIG. 1 is a schematic vertical sectional front view of the image forming apparatus, and FIG. 2 is a partially enlarged vertical sectional view around the intermediate transfer belt shown in FIG. This image forming apparatus is of a color printing type in which a toner image is transferred onto a sheet using an intermediate transfer belt.

  As shown in FIG. 1, a paper feed cassette 3 is disposed below the inside of the main body 2 of the image forming apparatus 1. The paper feed cassette 3 stores and accommodates paper P such as cut paper before printing. The sheets P are separated and sent one by one toward the upper left of the sheet cassette 3 in FIG. The paper feed cassette 3 can be pulled out horizontally from the front side of the main body 2.

  A first paper transport unit 4 is provided inside the main body 2 and to the left of the paper feed cassette 3. The first paper transport unit 4 is formed substantially vertically along the left side surface of the main body 2. The first paper transport unit 4 receives the paper P sent out from the paper feed cassette 3 and transports the paper P vertically upward along the left side surface of the main body 2 to the secondary transfer unit 40.

  A manual paper feed unit 5 is provided above the paper feed cassette 3 at a location on the right side which is the side opposite to the left side of the main body 2 where the first paper transport unit 4 is formed. Yes. In the manual paper feed unit 5, paper of a size that is not in the paper feed cassette 3, or paper that is to be manually fed, such as thick paper and OHP sheets, is placed.

  A second paper transport unit 6 is provided on the left side of the manual paper feed unit 5. The second paper transport unit 6 is located immediately above the paper feed cassette 3, extends substantially horizontally from the manual paper feed unit 5 to the first paper transport unit 4, and joins the first paper transport unit 4. Then, the second paper transport unit 6 receives the paper P or the like sent from the manual paper feed unit 5 and transports it to the first paper transport unit 4 substantially horizontally.

  On the other hand, the image forming apparatus 1 receives document image data from an external computer (not shown). The information of the image data is sent to the optical scanning device 7 which is an exposure unit disposed above the second paper transport unit 6. The laser beam L controlled based on the image data by the optical scanning device 7 is emitted toward the image forming unit 20.

  As shown in FIGS. 1 and 2, a total of four image forming units 20 are used above the optical scanning device 7, and an intermediate transfer member is used in the form of an endless belt above each image forming unit 20. An intermediate transfer belt 8 is provided. The intermediate transfer belt 8 is supported by being wound around a plurality of rollers, and is rotated clockwise in FIG. 2 by a driving device (not shown).

  As shown in FIGS. 1 and 2, the four image forming units 20 are arranged in a row from the upstream side to the downstream side in the rotational direction along the rotational direction of the intermediate transfer belt 8 in a so-called tandem system. is there. The four image forming units 20 are, in order from the upstream side, a magenta image forming unit 20M, a cyan image forming unit 20C, a yellow image forming unit 20Y, and a black image forming unit 20B. These image forming units 20 are replenished with a developer (toner) by a developer supply container and a conveying unit (not shown) corresponding to each color. In the following description, the identification symbols “M”, “C”, “Y”, and “B” are omitted unless particularly limited.

  In each image forming unit 20, an electrostatic latent image of a document image is formed by the laser light L emitted by the optical scanning device 7 that is an exposure unit, and a toner image is developed from the electrostatic latent image. The toner image is primarily transferred to the surface of the intermediate transfer belt 8 by the primary transfer unit 30 provided above each image forming unit 20. As the intermediate transfer belt 8 rotates, the toner image of each image forming unit 20 is transferred to the intermediate transfer belt 8 at a predetermined timing, so that the surface of the intermediate transfer belt 8 is magenta, cyan, yellow, or black. A color toner image is formed by superimposing the color toner images.

  A secondary transfer unit 40 including a secondary transfer roller 41 is disposed at a position where the intermediate transfer belt 8 is suspended on the sheet conveyance path. The color toner image once carried on the surface of the intermediate transfer belt 8 is formed by the intermediate transfer belt 8 and the secondary transfer roller 41 being in pressure contact with the paper P sent in synchronization by the first paper transport unit 4. Is transferred at the secondary transfer nip portion.

  After the secondary transfer, deposits such as toner remaining on the surface of the intermediate transfer belt 8 are cleaned for the intermediate transfer belt 8 provided upstream of the intermediate transfer belt 8 in the rotation direction of the magenta image forming unit 20M. It is cleaned and collected by the device 50. The configuration of the intermediate transfer belt cleaning device 50 will be described in detail later.

  A fixing unit 10 is provided above the secondary transfer unit 40. The paper P carrying the unfixed toner image in the secondary transfer unit 40 is sent to the fixing unit 10 where the toner image is heated and pressed by the heat roller and the pressure roller to be fixed.

  A branch portion 11 is provided above the fixing portion 10. The sheet P discharged from the fixing unit 10 is discharged from the branching unit 11 to the sheet discharging unit 12 provided on the upper part of the image forming apparatus 1 when double-sided printing is not performed.

  The discharge port portion from which the paper P is discharged from the branch portion 11 toward the paper discharge portion 12 functions as the switchback portion 13. When performing duplex printing, the switchback unit 13 switches the transport direction of the paper P discharged from the fixing unit 10. Then, the sheet P is sent downward through the branching unit 11, the left side of the fixing unit 10, and the left side of the secondary transfer unit 40, and again passes through the first sheet transport unit 4 to the secondary transfer unit 40. Sent.

  Next, a detailed configuration around the image forming unit 20 and the intermediate transfer belt 8 of the image forming apparatus 1 will be described with reference to FIG. 3 in addition to FIG. FIG. 3 is a partially enlarged vertical sectional view showing the periphery of the image forming unit. Since the four color image forming units 20 have the same structure, the identification symbols “M”, “C”, “Y”, and “B” are omitted as described above.

  As shown in FIG. 3, the image forming unit 20 includes a photosensitive drum 21 that is an image carrier at the center thereof. In the vicinity of the photosensitive drum 21, a charging device 60, a developing device 70, a charge eliminating device 80, and a drum cleaning device 90 are arranged in this order along the rotation direction. The primary transfer unit 30 is provided between the developing device 70 and the charge removal device 80 along the rotation direction of the photosensitive drum 21.

  The photoconductor drum 21 extends in the paper width direction perpendicular to the paper conveyance direction in the image forming apparatus 1, that is, the depth direction of the paper surface in FIG. The photosensitive drum 21 is an inorganic photosensitive drum in which an amorphous silicon photosensitive layer, which is an inorganic photoconductive material, is provided on the outer side of a conductive roller-shaped substrate made of aluminum or the like by vacuum deposition or the like, and has a diameter of 30 mm. It is. The photosensitive drum 21 is rotated by a driving device (not shown) so that the peripheral speed thereof is substantially the same as the paper conveyance speed (for example, 150 mm / s). Note that the four image forming apparatuses 20 shown in FIG. 2 are rotated by individual drive devices each having a motor and a gear.

  The charging device 60 includes a charging roller 62 in contact with the photosensitive drum 21 inside the housing 61. The charging roller 62 is pressed against the photosensitive drum 21 with a predetermined pressure, and rotates according to the rotation of the photosensitive drum 21. By this charging roller 62, the surface of the photosensitive drum 21 is uniformly charged with a predetermined polarity and potential. A cleaning brush 63 is provided in the housing 61 at a position separating the charging roller 62 from the photosensitive drum 21, and the surface of the charging roller 62 is cleaned by the cleaning brush 63.

  The developing device 70 includes a developing roller 72 and a supply screw 73 inside the housing 71. The developing roller 72 is provided in the vicinity of the photosensitive drum 21 with a developing method being contact or non-contact. A bias having the same polarity as the charging polarity of the photosensitive drum 21 is applied to the developing roller 72. The developing roller 72 charges the toner, which is a developer, and moves it to the electrostatic latent image on the surface of the photosensitive drum 21 to develop the electrostatic latent image.

  The developing device 70 uses a two-component toner obtained by mixing a magnetic carrier and a non-magnetic toner as a developer, but may be of a type using a magnetic or non-magnetic one-component toner. Absent. Further, in order to clean the surface of the photosensitive drum 21 by polishing, a small amount of powder such as titanium oxide or silica is mixed in the toner as an external additive. The toner is accommodated in a developer supply container (not shown), conveyed to a location of the developing device 70 by a conveying means (not shown), and replenished inside the housing 71 by a supply screw 73.

  The primary transfer unit 30 is provided with a primary transfer roller 31 that comes into contact with the photosensitive drum 21 via the intermediate transfer belt 8. The primary transfer roller 31 is a roller having a diameter of 20 mm, in which an EPDM (ethylene propylene diene rubber) foam having a thickness of 6 mm is provided on a metal shaft having a diameter of 8 mm. The primary transfer roller 31 does not have a driving device, and rotates according to the rotation of the intermediate transfer belt 8 by contacting the intermediate transfer belt 8. Further, a primary transfer bias having a polarity different from the charging polarity of the photosensitive drum 21 and the toner is applied to the primary transfer roller 31 as necessary.

  As shown in FIG. 2, the intermediate transfer belt 8 is wound around and supported by a plurality of rollers. The intermediate transfer belt 8 is an elastic endless belt provided by laminating an elastic layer on the surface of a substrate. A PVDF (polyvinylidene fluoride) resin having a thickness of 0.1 mm is used as a base material of the intermediate transfer belt 8, and an NBR rubber (nitrile rubber) having a thickness of 0.1 mm is provided as an elastic layer on the surface thereof. Further, the elastic layer is coated with PTFE (polytetrafluoroethylene) having a thickness of 10 μm.

  Among the rollers that support the intermediate transfer belt 8, as shown in FIG. 2, a roller provided at a location facing the secondary transfer roller 41 across the intermediate transfer belt 8 is driven in the vicinity of the secondary transfer portion 40. This is a roller 8a. The drive roller 8a is connected to a stepping motor (not shown) that is a drive motor, and rotates the intermediate transfer belt 8 at a speed of 150 mm / s. The driving roller 8a is a roller having a diameter of 30 mm, in which EPDM (ethylene propylene diene rubber) is provided with a thickness of 1.5 mm on a metal shaft having a diameter of 27 mm.

  On the other hand, the secondary transfer roller 41 is a roller having a diameter of 24 mm in which a metal shaft having a diameter of 10 mm is provided with an EPDM (ethylene propylene diene rubber) foam having a thickness of 7 mm. The secondary transfer roller 41 is rotated by obtaining power through a gear from a drive motor connected to a drive roller 8 a that rotates the intermediate transfer belt 8. Further, a secondary transfer bias having a polarity different from the charging polarity of the photosensitive drum 21 and the toner is applied to the secondary transfer roller 41 as necessary.

  As shown in FIG. 3, the static eliminator 80 of the image forming unit 20 is disposed on the downstream side of the primary transfer unit 30 along the rotation direction of the photosensitive drum 21. The static eliminating device 80 includes an LED (light emitting diode) 81 and a reflecting plate 82. The LED 81 is attached to the upper surface of the housing 91 of the cleaning device 90. Instead of the LED 81, an EL (electroluminescence) light source, a fluorescent lamp, or the like can be used. The reflection plate 82 is provided above the LED 81 so as to cover the LED 81. The neutralizing device 80 irradiates the photosensitive drum 21 with the neutralizing light from the LED 81 to remove the charged charge on the surface thereof, and prepares for the charging process in the next image forming operation.

  The cleaning device 90 for the photosensitive drum 21 is disposed further downstream of the primary transfer unit 30 and the charge removal device 80 along the rotation direction of the photosensitive drum 21. The drum cleaning device 90 includes a cleaning roller 92, a cleaning blade 93, a toner receiving member 94, a transport paddle 95, and a toner discharge screw 96 inside the housing 91. The cleaning roller 92 and the cleaning blade 93 are in pressure contact with the photosensitive drum 21, and remove adhering matters such as toner remaining on the surface of the photosensitive drum 21 for cleaning. The toner removed from the surface of the photosensitive drum 21 is temporarily stored inside the toner receiving member 94, and the toner overflowing from the toner receiving member 94 is sent to the toner discharge screw 96 through the transport paddle 95. Thus, the waste toner is discharged by the toner discharge screw 96 to a waste toner collection container (not shown) outside the cleaning device 90.

  Next, a detailed configuration of the cleaning device 50 for the intermediate transfer belt 8 will be described with reference to FIGS. 4 to 6 in addition to FIG. 4 is a partially enlarged vertical sectional view showing the periphery of the intermediate transfer belt cleaning device, FIG. 5 is a top view showing the intermediate transfer belt and a fur brush in contact with the intermediate transfer belt, and FIG. 5 is a fur brush in contact with the intermediate transfer belt. FIG.

  As described above, the cleaning device 50 for the intermediate transfer belt 8 is disposed on the upstream side in the rotation direction of the magenta image forming unit 20M with respect to the intermediate transfer belt 8 (see FIG. 2). The intermediate transfer belt cleaning device 50 includes a fur brush 52 that is a brush roller as a cleaning roller, a collection roller 53, and a discharge screw 54 inside a housing 51.

  The fur brush 52 is provided at a location facing the driven roller 8b that supports the intermediate transfer belt 8 around which the intermediate transfer belt 8 is wound. That is, the driven roller 8 b is a facing roller that faces the fur brush 52 with the intermediate transfer belt 8 interposed therebetween. The fur brush 52 is a rotating brush roller in which animal fur and synthetic fibers are formed in a cylindrical shape around a core metal having a diameter of 8 mm.

  Here, as shown in FIGS. 5 and 6, the intermediate transfer belt 8 has an effective image area 8R (an area in which diagonal lines are drawn in the drawing) in a range shorter than the entire width in the sheet width direction by a predetermined length. ) Is provided. Normally, the toner image is primarily transferred into the effective image area 8R of the intermediate transfer belt 8.

  The intermediate transfer belt 8 includes ribs 8c serving as a meandering prevention mechanism on the outside of the effective image area 8R, that is, on the inside of the both ends in the paper width direction. The ribs 8 c are made of urethane rubber, have a rectangular parallelepiped shape with a width of 5 mm and a thickness of 3 mm extending along the circumferential direction of the intermediate transfer belt 8, and project further inward from the inner surface of the intermediate transfer belt 8.

  On the other hand, the driven roller 8b has an axial length corresponding to the effective image area 8R of the intermediate transfer belt 8 as shown in FIGS. 5 and 6, and both ends of the intermediate transfer belt 8 in the sheet width direction. It is arrange | positioned inside the rib 8c. Therefore, when the intermediate transfer belt 8 is displaced in the paper width direction, the rib 8c comes into contact with the axial end surface of the driven roller 8b, and the displacement of the intermediate transfer belt 8, that is, meandering can be prevented.

  On the other hand, the fur brush 52 has an axial length longer than the effective image area 8R of the intermediate transfer belt 8 and has substantially the same axial length as the intermediate transfer belt 8, as shown in FIG. The fur brush 52 includes a large-diameter portion 52a having a larger diameter than a portion corresponding to the effective image region 8R at a position outside the effective image region 8R of the intermediate transfer belt 8. The fur brush 52 has a diameter of 16 mm at a hair tip portion at a position corresponding to the effective image area 8R, and a diameter of 20 mm at a hair tip portion of the large diameter portion 52a. It is arranged so as to be in pressure contact with the surface. In addition, the large diameter part 52a of the fur brush 52 can also be made into the form from which the other location and material of the fur brush 52 change, and the elasticity, the shape of a brush fiber, etc. differ.

  Further, the fur brush 52 is rotated by a motor (not shown) in such a direction that the hair tip portion moves in a direction different from the surface of the intermediate transfer belt 8. The fur brush 52 serves to collect deposits such as residual toner from the surface of the intermediate transfer belt 8.

  The collection roller 53 is disposed at a location separating the fur brush 52 from the intermediate transfer belt 8. The collection roller 53 is configured in such a manner that rubber is provided around the core bar, and has substantially the same length in the rotation axis direction as the fur brush 52. The collection roller 53 is arranged in pressure contact with the fur brush 52 so as to bite from the surface constituted by the fur tips of the fur brush 52 toward the axis of the fur brush 52. The collection roller 53 is rotated by a motor (not shown) in such a direction that the surface at the contact point with the fur brush 52 moves in the same direction as the surface of the fur brush 52. The collection roller 53 plays a role of collecting deposits such as residual toner from the surface of the fur brush 52.

  The discharge screw 54 is provided in the housing 51 below the collection roller 53 and further away from the collection roller 53 with respect to the intermediate transfer belt 8. The discharge screw 54 extends from the inside of the housing 51 to a waste toner collection container (not shown) provided outside the intermediate transfer belt cleaning device 50. The discharge screw 54 serves to discharge waste toner and the like in the housing 51 removed from the surface of the intermediate transfer belt 8 to the outside of the housing 51, that is, to a waste toner collection container.

  Next, the effect when the surface of the intermediate transfer belt 8 is cleaned using the intermediate transfer belt cleaning device 50 will be described with reference to FIG. FIG. 7 is a graph showing the effect of the presence or absence of the large diameter portion of the fur brush on the amount of toner accumulated at the end of the intermediate transfer belt.

  Using the image forming apparatus 1 equipped with the intermediate transfer belt cleaning device 50 according to the present invention, an image forming operation was performed up to 10,000 sheets. Then, after printing 500 sheets, 1000 sheets, 2000 sheets, 5000 sheets, and 10,000 sheets, the amount of toner accumulated at the end of the intermediate transfer belt 8 in the sheet width direction was measured.

  As a comparative example, a fur brush having no large-diameter portion and having substantially the same axial length as that of the effective image area 8R of the intermediate transfer belt 8 is used. The amount of toner accumulated at the edge was measured.

  According to FIG. 7, when the surface of the intermediate transfer belt 8 is cleaned by the cleaning device that does not have a large-diameter portion in the comparative example of the fur brush, a large amount of toner is required until 1000 sheets are printed on the end of the intermediate transfer belt 8 in the paper width direction It is clear that the toner amount has increased since then. On the other hand, in the cleaning of the surface of the intermediate transfer belt 8 by the cleaning device 50 having the large diameter portion 52a in the fur brush 52 according to the present invention, compared with the case of the cleaning device in which the fur brush does not have the large diameter portion. It can be confirmed that the amount of toner accumulated at the end of the transfer belt 8 in the paper width direction is clearly small and almost no absolute amount is generated.

  As described above, in the cleaning device 50 provided with the cleaning roller that removes deposits on the surface while rotating in contact with the intermediate transfer belt 8 that is an intermediate transfer member, the cleaning roller is effective for the intermediate transfer belt 8. The fur brush 52 is a brush roller having a longer axial length than the image area 8R, and a large-diameter portion 52a having a diameter larger than that corresponding to the effective image area 8R is provided at a position outside the effective image area 8R. Therefore, the fur brush 52 as a cleaning roller can be brought into contact with a portion outside the effective image region 8R of the intermediate transfer belt 8, and even if the outer portion is undulated, the large diameter portion 52a can be contacted. It is possible to make a stable contact by working. In this way, it is possible to provide the cleaning device 50 that can reliably bring the fur brush 52 into contact with not only the effective image area 8R on the surface of the intermediate transfer belt 8 but also the entire area thereof and can maintain a suitable cleaning performance. can do.

  In the present invention, since the cleaning device 50 is mounted on the image forming apparatus 1, the fur brush 52 is reliably brought into contact with not only the effective image region 8R on the surface of the intermediate transfer belt 8 but also the entire region thereof, and suitable cleaning performance is achieved. Can be maintained, and an image forming apparatus 1 capable of performing high-quality image formation can be obtained.

  Further, the image forming apparatus 1 includes a driven roller 8b that is a counter roller facing the fur brush 52 with the intermediate transfer belt 8 therebetween, and the driven roller 8b corresponds to the effective image area 8R of the intermediate transfer belt 8. Since the rib 8c as a meandering prevention mechanism for the intermediate transfer belt 8 is provided, the driven roller 8b does not exist up to an area outside the effective image area 8R of the intermediate transfer belt 8, Even if the undulation of the intermediate transfer belt 8 in the outer region is severe, the fur brush 52 can be effectively and stably brought into contact with the surface of the intermediate transfer belt 8 by the action of the large diameter portion 52a. Therefore, it is possible to provide the image forming apparatus 1 that can maintain a suitable cleaning performance while preventing the meandering of the intermediate transfer belt 8 and can perform image formation with higher quality.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  INDUSTRIAL APPLICABILITY The present invention can be used in a cleaning device that transfers a toner image onto a sheet and then removes deposits such as toner remaining on the surface of the intermediate transfer member for cleaning.

1 is a schematic vertical sectional front view of an image forming apparatus equipped with a cleaning device according to an embodiment of the present invention. FIG. 2 is a partially enlarged view of a vertical cross section around an intermediate transfer belt shown in FIG. 1. FIG. 3 is an enlarged view of a vertical cross section around the image forming unit shown in FIG. FIG. 3 is a partially enlarged vertical sectional view showing the periphery of the intermediate transfer belt cleaning device of FIG. 2. FIG. 5 is a top view showing the intermediate transfer belt of FIG. 4 and a fur brush in contact with the intermediate transfer belt. FIG. 6 is a perspective view showing the intermediate transfer belt of FIG. 5 and a fur brush in contact with the intermediate transfer belt. 6 is a graph showing the effect of the presence or absence of a large diameter portion of a fur brush on the amount of toner accumulated at an end portion of an intermediate transfer belt.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Main body 8 Intermediate transfer belt (intermediate transfer body)
8b Follower roller (opposing roller)
8c rib 8R effective image area 20 image forming unit 21 photosensitive drum 50 intermediate transfer belt cleaning device (cleaning device)
52 Fur brush (cleaning roller, brush roller)
52a Large diameter part

Claims (1)

In an image forming apparatus provided with a cleaning roller that removes deposits on the surface while rotating in contact with an intermediate transfer belt ,
The cleaning roller is a brush roller having an axial length longer than the effective image area of the intermediate transfer belt , and has a larger diameter at a position outside the effective image area than a position corresponding to the effective image area. With a diameter section,
The intermediate transfer belt, the provided axially opposite ends outside of the inner surface of the effective image region, a rib extending along the circumferential direction of the intermediate transfer belt to protrude inwardly away from the inner surface of the intermediate transfer belt,
Wherein the said has an axial length corresponding to the effective image area located axially inward of said ribs provided on both axial ends of the inner surface of the intermediate transfer belt of the intermediate transfer belt, separating the intermediate transfer belt An image forming apparatus comprising an opposing roller facing the cleaning roller.

Images