JP2009134153A - Cleaning device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning device capable of obtaining a satisfactory cleaning performance. <P>SOLUTION: The cleaning device includes: a fur brush roller 111 for removing toner on the surface of an intermediate transfer belt 8; and a recovery roller 112 and blade 113 for recovering toner from the brush roller 111. The length L of a first nip part 120 formed by an intermediate transfer belt 8 and a counter roller 23 disposed opposite the fur brush roller 111 with the intermediate transfer belt 8 between them is shorter than the length L2 of a second nip part 130 formed by the fur brush roller 111 and intermediate transfer belt 8. The position of the middle 130M of second nip part 130 is deviated downstream from the position of the middle 120M of a first nip part 120 in the moving direction of the intermediate transfer belt 8. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cleaning device and an image forming apparatus.

  In recent years, not only monochrome but also full-color image forming apparatuses are often used. As such a full-color image forming apparatus, two types, a one-drum type and a tandem type, are often used, and in either case, toners of four types of colors, magenta, yellow, cyan, and black, are superimposed. As a result, a full-color image is formed.

  The image formation will be described by taking a tandem type image forming apparatus as an example. In the tandem type image forming apparatus, four image forming units of magenta, yellow, cyan, and black are separately provided. The toner images formed on the photosensitive drum for each color toner are once superimposed on the intermediate transfer belt. Next, the superimposed toner images are transferred from the intermediate transfer belt to a recording medium such as paper and fixed on the recording medium.

  When transferring from the intermediate transfer belt to the recording medium, since the transfer rate is not 100%, the toner remains on the intermediate transfer belt, but if the toner remains, it appears in the next image as dirt, An image defect occurs. For this reason, a cleaning device for removing residual toner from the intermediate transfer belt is provided (for example, see Patent Document 1).

  FIG. 8 is a schematic diagram of a conventional cleaning device 100. As shown in FIG. 8, the conventional cleaning device 100 includes a fur brush roller 102 for removing toner from the surface of the intermediate transfer belt 101, a collecting roller 103 for collecting toner from the fur brush roller 102, and a collecting roller 103. A blade 104 that removes toner from the toner, and a conveyance spiral 105 that conveys the toner removed by the blade 104 to a waste toner bottle. A counter roller 106 is provided at a position facing the fur brush roller 102 with the intermediate transfer belt 101 interposed therebetween, and the counter roller 106 is grounded. On the other hand, since a voltage is applied to the collection roller 103, an electric field is generated between the fur brush roller 102 and the opposing roller 106 that are in contact with the collection roller 103. Residual toner on the intermediate transfer belt 101 is removed by the electrical action by the electric field and the mechanical scraping action by the brush of the fur brush roller 102.

In the cleaning device shown in FIG. 8, the length L _X of the nip portion X between the intermediate transfer belt 101 and the counter roller 106 is longer than the length L _Y of the nip portion Y between the fur brush roller 102 and the intermediate transfer belt 101. The length of the nip portion Y is set to be within the nip portion X.

Thus, since the entire area of the nip portion Y is set to be within the nip portion X, an electric field is generated substantially uniformly over the entire area of the nip portion Y between the fur brush roller 102 and the intermediate transfer belt 101. The toner can be effectively removed from the intermediate transfer belt 101.
JP 2005-258167 A

However, due to restrictions due to the arrangement of other components in the image forming apparatus, the length of the nip portion X between the intermediate transfer belt 101 and the counter roller 106 cannot be sufficiently secured, and the length L _X of the nip portion X is not equal to the nip. it may be shorter than the length L _Y parts Y.

  In such a case, a uniform electric field is not formed over the entire nip portion Y between the fur brush roller 102 and the intermediate transfer belt 101, and the strength of the electric field is generated, depending on the positional relationship between the opposing roller 106 and the fur brush roller 102. In some cases, sufficient cleaning performance may not be obtained.

  An object of the present invention is to provide a cleaning device and an image forming apparatus capable of obtaining sufficient cleaning performance in consideration of the problems of the conventional cleaning device.

In order to achieve the above object, the first present invention provides:
A cleaning member for removing the developer on the surface of the intermediate transfer member;
A recovery unit for recovering the developer from the cleaning member,
The length of the first nip portion formed by the counter member disposed opposite to the cleaning member and the intermediate transfer member sandwiching the intermediate transfer member is formed by the cleaning member and the intermediate transfer member. Smaller than the length of the second nip,
With reference to the moving direction of the intermediate transfer member, the center position of the second nip portion coincides with the center position of the first nip portion via the intermediate transfer member or on the downstream side. This is a cleaning device.

The second aspect of the present invention is
The cleaning member is a fur brush roller;
The collection unit
A collection roller that contacts the fur brush roller and collects the developer from the fur brush roller;
The cleaning device according to the first aspect of the present invention includes a blade that removes the developer from the collection roller.

The third aspect of the present invention
A plurality of image carriers on which developer images are formed; and
An intermediate transfer belt on which a plurality of developer images formed for each image carrier are transferred and superimposed;
A primary transfer member provided to face each of the plurality of image carriers with the intermediate transfer belt interposed therebetween;
A secondary transfer member for secondary transfer of the developer image from the intermediate transfer belt onto a recording medium;
The first or second cleaning device of the present invention for removing the developer remaining on the surface of the intermediate transfer belt after the secondary transfer to the recording medium,
The intermediate transfer member is an image forming apparatus that is the intermediate transfer belt.

The fourth aspect of the present invention is
One image carrier on which a plurality of developer images are sequentially formed on the surface;
An intermediate transfer belt on which the plurality of developer images are transferred and superimposed;
A primary transfer member provided to face the image carrier with the intermediate transfer member interposed therebetween;
A secondary transfer member for secondary transfer of the developer image from the intermediate transfer belt onto a recording medium;
A cleaning device according to the first or second aspect of the present invention for removing developer remaining on the surface of the intermediate transfer member after secondary transfer to the recording medium,
The intermediate transfer member is an image forming apparatus that is the intermediate transfer belt.

  According to the present invention, it is possible to provide a cleaning device and an image forming apparatus capable of obtaining sufficient cleaning performance.

  Hereinafter, a copying machine as an embodiment of the image forming apparatus according to the present invention will be described with reference to the drawings, and an example of the cleaning apparatus of the present invention will be described.

(Embodiment 1)
FIG. 1 is a front sectional view of a copying machine according to a first embodiment of the present invention. As shown in FIG. 1, the copying machine 1 according to the first embodiment includes a plurality of paper feed cassettes 2 for storing paper on which images are formed on the bottom. In addition, the copying machine 1 includes a document reading unit 3 that reads an image of a document by using an exposure lamp, a lens, a mirror, and the like.

  The copying machine 1 according to the present embodiment is a color copying machine using a tandem method, and includes a black image forming unit 4, a yellow image forming unit 5, a cyan image forming unit 6, and a magenta arranged in order in the horizontal direction. An image forming unit 7 is provided. An intermediate transfer belt 8 for superimposing images formed by these image forming units is disposed. Further, a secondary transfer unit 9 that transfers the toner image superimposed on the intermediate transfer belt 8 to a sheet and a fixing unit 10 that fixes the transferred toner image to the sheet are provided.

  A registration roller 25 is provided upstream of the secondary transfer unit 9 in the paper conveyance direction, and a conveyance belt 26 for conveying the paper is provided between the secondary transfer unit 9 and the fixing unit 10. It has been. Further, a discharge roller pair 12 for discharging the paper that has passed through the fixing unit 10 to the outside of the copying machine 1 is provided on the side surface, and a discharge tray 13 on which the paper discharged by the discharge roller pair 12 is placed is provided. Is provided. In FIG. 1, the sheet conveyance direction is indicated by an arrow E.

  Next, the image forming unit will be described. Since the basic configurations of the four image forming units 4, 5, 6, and 7 are the same, the black image forming unit 4 will be described as an example. As shown in FIG. 1, the black image forming unit 4 includes a photosensitive drum 40 made of amorphous silicon, a charger 41, a developing unit 42, a cleaning unit 43, a static eliminator 44, and the like. A laser scanner unit (hereinafter referred to as LSU) 46 that forms an electrostatic latent image by optically scanning the surface of the photosensitive drum 40 charged by the charger 41 of the black image forming unit 4 is a photosensitive drum. 40 is provided above. Similarly, the other image forming units 5, 6, 7 also have photosensitive drums 50, 60, 70, chargers 51, 61, 71, developing units 52, 62, 72, cleaning units 53, 63, 73, static eliminators. 54, 64, 74 and LSUs 56, 66, 76 and the like.

  Further, primary transfer rollers 14, 15, 16, and 17 are disposed so as to face the photosensitive drums 40, 50, 60, and 70 with the intermediate transfer belt 8 interposed therebetween. The developing units 42, 52, 62, and 72 are provided with developing rollers 45 and 55 that are disposed in contact with the photosensitive drums to supply toner to the surfaces of the photosensitive drums 40, 50, 60, and 70, respectively. , 65, 75 are provided. For example, the intermediate transfer belt 8 is provided with a layer of an elastic member such as rubber on a resin belt in order to achieve both running performance and high image quality.

  The secondary transfer unit 9 includes a secondary transfer roller 92 to which a voltage is applied, and a driven roller 21 provided inside the intermediate transfer belt 8 so as to face the secondary transfer roller 92. The driven roller 21 is grounded. A driving roller 24 is provided inside the intermediate transfer belt 8 in the vicinity of the downstream side of the black image forming unit 4, and the intermediate transfer belt 8 rotates in the direction of arrow A as the driving roller 24 rotates. A driven roller 22 is provided inside the intermediate transfer belt 8 in the vicinity of the upstream side of the magenta image forming unit 7.

  A cleaning device 11 for removing residual toner on the surface of the intermediate transfer belt 8 is disposed on the upstream side of the driven roller 22 and on the downstream side of the secondary transfer unit 9. A counter roller 23 is provided inside the intermediate transfer belt 8 so as to face the cleaning device 11.

  Next, the cleaning device 11 as an example of the present invention will be described.

  FIG. 2A is a schematic diagram of the cleaning device 11 of the present embodiment. As shown in FIG. 2A, the cleaning device 11 is disposed in contact with the fur brush roller 111 and the fur brush roller 111 disposed to face the facing roller 23 with the intermediate transfer belt 8 interposed therebetween. A collecting roller 112 and a rubber blade 113 for removing toner on the collecting roller 112. A conveyance spiral 115 for conveying the collected toner to a toner disposal box (not shown) is disposed below the rubber blade 113. A casing 116 is provided so as to cover the fur brush roller 111, the recovery roller 112, the blade 113, and the conveying spiral 115 from below.

  Further, the rotation direction B of the fur brush roller 111 is a direction facing the rotation direction A of the intermediate transfer belt 8 at a portion in contact with the intermediate transfer belt 8. The rotation direction C of the collection roller 112 is the same as the rotation direction B at the portion in contact with the fur brush roller 111.

  Further, the fur brush roller 111 in FIG. 2 (a) is obtained by winding the fiber 111b around the roller portion 111a as shown in FIG. 2 (b). Toner is scraped off the surface.

  Further, one of the bearings of the collection roller 112 is conductive, and a voltage application unit 114 that supplies a voltage to the collection roller 112 through this bearing is provided. On the other hand, the bearing of the fur brush roller 111 is non-conductive, and the voltage applied to the recovery roller 112 can act as a cleaning voltage without loss. Since the toner supplied to the photosensitive drums 40, 50, 60, and 70 is positively charged, a current of about −10 μA is applied to the recovery roller 112 so that the surface of the fur brush roller 111 is negatively charged. The opposing roller 23 arranged to face the collection roller 112 is grounded.

  Therefore, a current flows from the collection roller 112 to the ground of the opposing roller 23 via the fur brush roller 111 and the intermediate transfer belt 8, and an electric field is formed between the fur brush roller 111 and the intermediate transfer belt 8. The toner on the transfer belt 8 moves to the fur brush roller 111 by electrical action.

  In FIG. 1, the configuration of other parts or the like is not shown in the intermediate transfer belt 8 for the sake of explanation. The width of the nip portion between the intermediate transfer belt 8 and the intermediate transfer belt 8 cannot be sufficiently secured. Therefore, in the cleaning device of the present embodiment, as shown in FIG. 2, the length L1 of the nip portion 120 between the opposing roller 23 and the intermediate transfer belt 8 is the nip portion between the fur brush roller 111 and the intermediate transfer belt 8. It is shorter than the length L2 of 130.

  Further, as shown in FIG. 2, the counter roller 23 and the fur brush roller 111 are arranged such that the center position 130M of the nip portion 130 is located downstream of the center position 120M of the nip portion 120 via the intermediate transfer belt 8. Is arranged.

  An example of the cleaning member of the present invention corresponds to the fur brush roller 111 of the present embodiment, and an example of the recovery unit of the present invention corresponds to the recovery roller 112 and the blade 113 of the present embodiment. An example of the first nip portion of the present invention corresponds to the nip portion 120 of the present embodiment, and an example of the second nip portion of the present invention corresponds to the nip portion 130 of the present embodiment. An example of the center position of the first nip portion of the present invention corresponds to the center position 120M, and an example of the center position of the second nip portion of the present invention corresponds to the center position 130M.

  An example of the plurality of image carriers of the present invention corresponds to the photosensitive drums 40, 50, 60, and 70. The primary transfer member of the present invention corresponds to the primary transfer rollers 14, 15, 16, and 17 of the present embodiment, and the secondary transfer member of the present invention corresponds to the secondary transfer roller 92 of the present embodiment.

  Next, the operation of the copying machine 1 according to the present embodiment will be described.

  A photoconductor uniformly charged by a charger in the magenta image forming unit 7, the cyan image forming unit 6, the yellow image forming unit 5 and the black image forming unit 4 based on the image data read by the document reading unit 3. An electrostatic latent image is formed by the LSUs 46, 56, 66, and 76 on the surfaces of the drums 40, 50, 60, and 70, and a toner image visualized by the developing units 42, 52, 62, and 72 is formed (see FIG. 1). ). At this time, the toners on the photosensitive drums 40, 50, 60, and 70 are positively charged, and magenta, cyan, yellow, and black are transferred by the primary transfer rollers 14, 15, 16, and 17 to which a negative voltage is applied. The toner images are superimposed on the intermediate transfer belt 8 in order. The toner remaining on the photosensitive drum by the primary transfer is removed by the cleaning units 43, 53, 63, and 73, and the surface of the photosensitive drum is charged by the static eliminators 44, 54, 64, and 74.

  At the same time, a sheet is fed from the sheet feeding cassette 2, temporarily stopped by the registration roller 25, and the secondary transfer unit 9 according to the movement timing of the area (image forming area) where the toner image is formed on the intermediate transfer belt 8. To be sent to.

  Then, the toner images superimposed on the intermediate transfer belt 8 are transferred onto the paper by the secondary transfer unit 9. Here, since the toner image is positively charged, a voltage is applied to the secondary transfer roller 92 so that the surface thereof is negatively charged. Constant current control is performed during the secondary transfer. Next, the sheet on which the toner image is fixed by the fixing unit 10 is discharged onto the discharge tray 13 through the discharge roller pair 12 (see FIG. 1). In order to prevent the fog toner and floating toner from adhering, the applied voltage of the secondary transfer roller 92 is switched so that the surface is again charged positively after the paper passes.

  Note that the toner remaining on the intermediate transfer belt 8 after the transfer to the paper is removed by the negatively charged fur brush roller 111 via the recovery roller 112 (see FIG. 2A).

  Here, as described above, a voltage is applied to the collection roller 112, and the opposing roller 23 is grounded. Therefore, a voltage difference is generated between the collection roller 112 and the fur brush roller 111, and between the fur brush roller 111 and the intermediate transfer belt 8, and the residual toner is electrostatically collected in the intermediate transfer belt 8, the fur brush roller 111, and the collection. It is sent to the rollers 112 in order.

  The toner that has moved to the collection roller 112 is removed from the collection roller 112 by the blade 113, and is conveyed to the toner disposal box by the conveyance spiral 115 and discarded.

  When printing of the read image data is completed, the operations of the photosensitive drum, the intermediate transfer belt 8, the secondary transfer roller 92, and the like are stopped, and the image forming operation is completed.

  In the copying machine 1 of the present embodiment, since the center position 130M of the nip portion 130 is downstream of the center position 120M of the nip portion 120, the length of the nip portion 120 between the opposing roller 23 and the intermediate transfer belt 8 is long. Even though L1 is shorter than the length L2 of the nip portion 130 between the fur brush roller 111 and the intermediate transfer belt 8, sufficient cleaning performance can be obtained.

  In the present embodiment, the center position 120M has shifted to the downstream side from the center position 130M, but sufficient cleaning performance is exhibited even when there is no shift (when they are aligned via the intermediate transfer belt 8). I can do it.

  Next, sufficient cleaning performance is obtained when the center position 130M coincides with the center position 120M via the intermediate transfer belt 8, or when the center position 130M is shifted downstream via the intermediate transfer belt 8. The following examples will be described in detail with respect to the point that can be performed.

Example 1
FIG. 3 is a schematic diagram illustrating the cleaning device 11 according to the first embodiment of the present invention.

In the cleaning device 11 shown in the first embodiment, the intermediate transfer belt 8 having a volume resistivity of 10 ¹⁰ Ω · cm is used. The intermediate transfer belt 8 includes a PVDF (polyvinylidene fluoride) layer, a CR (chloroprene rubber) layer, and a fluorine coating layer made of PTFE (polytetrafluoroethylene), which are sequentially formed from the inside toward the outside. .

  The counter roller 23 is made of SUS having an outer diameter of φ30 mm. The length L1 of the nip 130 between the facing roller 23 and the intermediate transfer belt 8 is set to about 2 mm.

Further, as the fur brush roller 111, one having an outer diameter of φ25 mm and a fiber density of 240 kF / inch ² is used, and as the fiber 111b, a polyester conductive yarn having a thickness of 2D is used as the fiber. The length L2 of the nip portion 130 between the fur brush roller 111 and the intermediate transfer belt 8 is set to about 4.9 mm.

  Further, the recovery roller 112 is made of SUS having an outer diameter of 18 mm, and the nip width with the fur brush roller 111 is set to 1.5 mm. The blade 113 is made of urethane.

  In the first exemplary embodiment, the center position 130M of the nip portion 130 is 5 mm downstream from the center position 120M of the nip portion 120 via the intermediate transfer belt 8 with respect to the moving direction A of the intermediate transfer belt 8. In addition, the positions of the facing roller 23 and the fur brush roller 111 are set. In FIG. 3, the distance W between the center position 120M and the center position 130M is 5 mm.

  Under this condition, the voltage applied to the fur brush roller 111 was changed, and the cleaning performance of the toner on the intermediate transfer belt 8 was evaluated.

(Example 2)
FIG. 4 is a schematic diagram of the cleaning device 11 according to the second embodiment of the present invention. As shown in FIG. 4, the basic configuration of the cleaning device 11 in the second embodiment is the same as that in the first embodiment, but the relationship between the center position 130M of the nip portion 130 and the center position 120M of the nip portion 120 is the same. Is different.

  In the cleaning device of the second embodiment, the center position 120M coincides with the center position 130M via the intermediate transfer belt 8. That is, the counter roller 23 and the fur brush roller 111 are arranged so that the center position 120M faces the center position 130M with the intermediate transfer belt 8 interposed therebetween.

(Comparative Example 1)
FIG. 5 is a schematic diagram of a cleaning device in Comparative Example 1 of the present invention. As shown in FIG. 5, the basic configuration of the cleaning device in Comparative Example 1 is the same as that in Example 1, but the relationship between the center position 130M of the nip portion 130 and the center position 120M of the nip portion 120 is different. .

  In the cleaning device of Comparative Example 1, the counter roller 23 is set so that the center position 130M of the nip portion 130 is 5 mm upstream from the center position 120M of the nip portion 120 with respect to the moving direction A of the intermediate transfer belt 8. And the position of the fur brush roller 111 are set. In FIG. 5, the distance W between the center position 120M and the center position 130M is 5 mm.

  The evaluation results of the cleaning performance in the configurations of Example 1, Example 2, and Comparative Example 1 are shown in (Table 1). Table 1 also shows the current value I when a voltage is applied.

  In the column “Non-transferred” in Table 1, after the toner image was formed on the intermediate transfer belt 8, the toner image conveyed without being transferred to the paper in the secondary transfer unit 9 was removed by the cleaning device 11. The cleaning performance was evaluated. The evaluation in “untransferred” is based on the state where the toner image transfer area of the intermediate transfer belt 8 has passed through the cleaning device 11 twice. When the transfer is not performed on the paper, a voltage is applied to the secondary transfer roller 92 so that the surface is charged with the same positive charge as that of the toner.

  The column “After transfer” in Table 1 shows the toner remaining on the intermediate transfer belt 8 after the toner image is formed on the intermediate transfer belt 8 and then transferred to paper in the secondary transfer unit 9. The cleaning performance when removed by the cleaning device 11 is evaluated. Note that the voltage applied to the secondary transfer roller 92 in the secondary transfer unit 9 when transferring to paper is -1.5 kV.

  Further, as the toner image, a solid image formed uniformly in a 20 × 20 mm range on the intermediate transfer belt 8 using the black image forming unit 4 was used.

  Further, “◯” indicates a state in which no toner remains, “Δ” indicates a state in which a small amount of toner remains, and “X” indicates a state in which toner remains. The residual toner amount at “Δ” is an amount that does not affect the image transferred to the paper even if the image forming operation is performed in this state.

  In the first embodiment, except for the case where no voltage is applied to the recovery roller 112, the cleaning performance is good for all “untransferred” and “after transfer” at all voltage values.

  In Example 2, when a voltage of 2 kV is applied to the collection roller 112 (current value 75 μA), the cleaning performance after transfer is Δ, but it is a level that does not affect the image transferred to the paper. Therefore, there is no problem in use.

  In Comparative Example 1, it can be seen that the applied voltage value is 0 to 0.75 kV and the cleaning performance in “untransferred” is not sufficient.

  As described above, from (Table 1), the center position 130M of the nip portion 130 coincides with the center position 120M of the nip portion 120 via the intermediate transfer belt 8, or via the intermediate transfer belt 8. Thus, it can be seen that good cleaning performance can be obtained when it is shifted downstream.

  The cleaning by the fur brush roller 111 is performed by the interaction between the mechanical brush scraping ability and the electric force. It is considered that sufficient cleaning performance can be obtained because the cleaning electric field becomes strong at the position where the brush fiber, which is a place where the brush fiber is released from the bent state.

(Embodiment 2)
Next, a copying machine according to Embodiment 2 of the present invention will be described. In the first embodiment, the case where the cleaning device is applied to a tandem type copying machine has been described. In the second embodiment, the case where the cleaning device is applied to a one-drum type color copying machine will be described.

  FIG. 6 is a partial schematic view of a one-drum type copying machine. The copying machine shown in FIG. 6 includes a single photosensitive drum 200 and a developing device 201 that supplies four types of toners of black, yellow, cyan, and magenta to the photosensitive drum 200 for each color. The developing device 201 includes a black developing device 201K, a yellow developing device 201Y, a cyan developing device 201C, and a magenta developing device 201M. By rotating, each developing device is placed at a developing position facing the photosensitive drum 200. By moving sequentially, toner images of opposite colors are formed on the surface of the photosensitive drum 200.

  Further, an intermediate transfer belt 202 is provided for superimposing developer images for respective colors. Inside the intermediate transfer belt 202, a primary transfer roller 203 is provided at a position facing the photosensitive drum 200, and in addition, a driving roller 204 and driven rollers 205 and 206 are also provided. The driven roller 205 is disposed at a position facing the secondary transfer roller 207 for secondary transfer of the toner image on the intermediate transfer belt 202 to the sheet, and the drive roller 204 is rotated in the rotational direction of the intermediate transfer belt 202 ( With reference to the arrow H), it is provided downstream of the primary transfer roller 203 and upstream of the driven roller 205. The driven roller 206 is provided on the upstream side of the primary transfer roller 203 and on the downstream side of the driven roller 205. The paper transport direction is indicated by an arrow I.

  A cleaning device 211 is disposed between the driven roller 206 and the driven roller 205. The cleaning device 211 includes a fur brush roller 111, a recovery roller 112, a blade 113, a voltage application unit 114 (not shown), and a transport spiral 115, similar to the cleaning device 11 described above. Covered. A counter roller 208 is provided inside the intermediate transfer belt 202 that faces the fur brush roller 111.

  FIG. 7 is a partially enlarged view of the vicinity of the opposing roller 208. FIG. 7 shows only the intermediate transfer belt 202, the opposing roller 208, and the fur brush roller 111. As shown in FIG. 7, a nip portion 220 is formed by the facing roller 208 and the intermediate transfer belt 202, and a nip portion 230 is formed by the fur brush roller 111 and the intermediate transfer belt 202.

  Next, the operation of the copying machine according to the second embodiment of the present invention will be described.

  In the image forming apparatus shown in FIG. 6, a toner image of one color is formed on the surface of the photosensitive drum 200, and after the toner image is primarily transferred to the intermediate transfer belt 202, the toner image of the other color is transferred to the photosensitive member. The toner image is formed on the surface of the drum 200 and is primarily transferred onto the previously transferred toner image. In this way, a toner image is sequentially formed on the photosensitive drum 200, and is primary-transferred over the intermediate transfer belt 202, whereby a color toner image is formed on the intermediate transfer belt 202. The cleaning device 211 is provided with a mechanism (not shown) for separating the fur brush roller 111 from the intermediate transfer belt 202. When the toner images are superimposed on the intermediate transfer belt 202, the intermediate transfer belt is used. The fur brush roller 111 is separated from the intermediate transfer belt 202 so as not to remove the toner image from the upper portion 202.

  Subsequently, the toner image formed on the intermediate transfer belt 202 is transferred to a recording medium such as paper by the secondary transfer roller 207.

  After this transfer, the toner remaining on the intermediate transfer belt 202 without being transferred to the recording medium is removed by the cleaning device 211 of the second embodiment. At this time, the fur brush roller 111 is in contact with the intermediate transfer belt 202.

  Here, as shown in FIG. 7, even in the case where the length L3 of the nip portion 220 is shorter than the length L4 of the nip portion 230, in the second embodiment, the moving direction H of the intermediate transfer belt 202 is shown. The counter roller 208 and the fur brush roller 111 are arranged so that the center position 230M of the nip portion 230 is shifted downstream from the center position 220M of the nip portion 220 via the intermediate transfer belt 202 with reference to the above. Therefore, as in the first embodiment, sufficient cleaning performance can be exhibited.

  As in FIG. 4 described in the first embodiment, a sufficient cleaning effect can be exhibited even when the center position 230M coincides with the center position 220M via the intermediate transfer belt 202.

  An example of one image carrier of the present invention corresponds to the photosensitive drum 200. The primary transfer member of the present invention corresponds to the primary transfer roller 203 of the present embodiment, and the secondary transfer member of the present invention corresponds to the secondary transfer roller 207 of the present embodiment.

  An example of the facing member of the present invention corresponds to the facing rollers 23 and 208 of the above embodiment, but is not limited to the roller shape, and any member that contacts the intermediate transfer belt 202 may be used.

  Further, the place where the cleaning devices 11 and 211 are disposed is not limited to the place described in the first and second embodiments.

  In the above embodiment, the color image forming apparatus has been described. However, the present invention is applicable to a monochrome image forming apparatus provided with an intermediate transfer belt.

  The cleaning device and the image forming apparatus of the present invention can obtain a sufficient cleaning performance, and are useful as a copying machine, a facsimile, a printer, and the like.

1 is a schematic front view of a copying machine according to a first embodiment of the present invention. (A) The schematic diagram of the cleaning apparatus in Embodiment 1 concerning this invention, (b) The schematic diagram of a fur brush roller Schematic diagram of the cleaning device in Example 1 according to the present invention. Schematic diagram of the cleaning device in Example 2 according to the present invention. Schematic diagram of the cleaning device in Comparative Example 1 The schematic diagram of the cleaning apparatus in Embodiment 2 concerning this invention. Partial enlarged view of FIG. Schematic diagram of a conventional cleaning device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Copier 2 Paper feed cassette 3 Image reading part 4 Black image forming part 5 Yellow image forming part 6 Cyan image forming part 7 Magenta image forming part 8 Intermediate transfer belt 9 Secondary transfer part 10 Fixing part 11 Cleaning device 12 Discharge roller pair 13 Discharge tray 23 Opposing roller 111 Fur brush roller 112 Recovery roller 113 Blade 114 Voltage application unit 115 Conveying spiral

Claims (4)

A cleaning member for removing the developer on the surface of the intermediate transfer member;
A recovery unit for recovering the developer from the cleaning member;
The length of the first nip portion formed by the counter member disposed opposite to the cleaning member and the intermediate transfer member sandwiching the intermediate transfer member is formed by the cleaning member and the intermediate transfer member. Shorter than the length of the second nip,
With reference to the moving direction of the intermediate transfer member, the center position of the second nip portion coincides with the center position of the first nip portion via the intermediate transfer member or on the downstream side. A cleaning device that is misaligned. The cleaning member is a fur brush roller;
The collection unit
A collection roller that contacts the fur brush roller and collects the developer from the fur brush roller;
The cleaning device according to claim 1, further comprising a blade that removes the developer from the collection roller. A plurality of image carriers on which developer images are formed; and
An intermediate transfer belt on which a plurality of developer images formed for each image carrier are transferred and superimposed;
A primary transfer member provided to face each of the plurality of image carriers with the intermediate transfer belt interposed therebetween;
A secondary transfer member for secondary transfer of the developer image from the intermediate transfer belt onto a recording medium;
A cleaning device according to claim 1 or 2, for removing developer remaining on the surface of the intermediate transfer belt after secondary transfer to the recording medium,
The image forming apparatus, wherein the intermediate transfer member is the intermediate transfer belt. One image carrier on which a plurality of developer images are sequentially formed on the surface;
An intermediate transfer belt on which the plurality of developer images are transferred and superimposed;
A primary transfer member provided to face the image carrier with the intermediate transfer member interposed therebetween;
A secondary transfer member for secondary transfer of the developer image from the intermediate transfer belt onto a recording medium;
A cleaning device according to claim 1 or 2, for removing developer remaining on the surface of the intermediate transfer member after secondary transfer to the recording medium,
The image forming apparatus, wherein the intermediate transfer member is the intermediate transfer belt.

Images