Image forming device

Abstract

To improve the effect of removing a toner adhered to a conveying member compared with simply performing electrostatic adsorption.SOLUTION: An image forming apparatus has: a toner conveying body being an endless belt that holds toner images or a transfer member that transfers the toner images to a recording medium nipped between the endless belt and the transfer member; an electric charge application member that is provided opposite to a surface of the toner conveying body and increases the electric charge of a toner adhered to the surface of the toner conveying body; and a toner attracting member that is provided on the downstream side of the electric charge application member in the direction of conveyance of the toner conveying body and is applied with a voltage having a polarity opposite to that of the toner adhered to the surface of the toner conveying body to attract the toner.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] Patent document 1 discloses an image forming apparatus having a transport member that transports at least one of a toner image and a paper sheet carrying a toner image, a static elimination device that eliminates static electricity from paper dust adhering to the transport member, and a removal device that is provided downstream of the static elimination device in the movement direction of the transport member and removes the toner and paper dust adhering to the transport member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-236988 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to improve the effect of removing toner adhering to a conveying member as compared with simple electrostatic adsorption. [Means for solving the problem]

[0005] The image forming apparatus described in claim 1 comprises a toner transport body which is an endless belt that holds a toner image or a transfer member that transfers a toner image to a recording medium nipped between the endless belt and the toner transport body, a charge imparting member that is disposed opposite to the surface of the toner transport body and increases the charge of toner adhering to the surface of the toner transport body, and a toner attracting member that is disposed downstream of the charge imparting member in the transport direction of the toner transport body and attracts the toner by applying a voltage of the opposite polarity to the toner adhering to the surface of the toner transport body.

[0006] In accordance with a second aspect of the present invention, in the image forming apparatus according to the first aspect, the toner attracting member is a roll brush that contacts the toner transport body.

[0007] The invention described in claim 3 is an image forming apparatus described in claim 1 or claim 2, in which the charge imparting member is arranged to slide against the toner on the moving toner transport body, and is a film made of a resin material that is more likely to impart a negative charge to the toner than the material constituting the toner transport body.

[0008] A fourth aspect of the present invention provides the image forming apparatus according to the third aspect, wherein the film is made of any one of polyurethane, polyethylene, polyimide, and polystyrene.

[0009] The invention described in claim 5 is an image forming apparatus described in any one of claims 1 to 4, wherein the charge applying member is provided with a wear-resistant layer made of a material having better wear resistance than the material constituting the charge applying member at a portion that comes into contact with the toner transport body. Effect of the Invention

[0010] According to the image forming apparatus of claim 1 of the present invention, the toner adhering to the toner transport body is more easily attracted by the downstream toner attraction member to which a voltage of the opposite polarity is applied, compared to the case where the toner adhering to the toner transport body is electrostatically attracted as is.

[0011] According to the image forming apparatus of the present invention, the toner on the toner transport body can be mechanically peeled off more easily than in the case where the toner is attracted by a detoning roll which is an electrostatic attraction member.

[0012] According to the image forming apparatus of the third aspect of the present invention, the toner can be more easily removed by the toner attracting member, compared to a case in which the toner transport body and the film have the same electrostatic charge series.

[0013] According to the image forming apparatus of the fourth aspect of the present invention, the toner can be charged more easily and the toner can be attracted more easily than in the case where the film is made of rubber.

[0014] According to the image forming apparatus of the fifth aspect of the present invention, wear of the charge applying member can be suppressed compared to the case where the charge applying member itself is in direct contact with the toner transport body. [Brief description of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention as viewed from the front side. [Diagram 2] FIG. 2 is a schematic diagram illustrating a toner image forming unit according to the present embodiment. [Diagram 3] FIG. 2A is a schematic diagram showing a cleaning device according to the present embodiment, and FIG. 2B is a cross-sectional view showing an example of a film. [Figure 4] FIG. 2 is a diagram showing a non-transferred image and a transferred image on a transfer belt. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] An example of an embodiment of the present invention will be described below with reference to the drawings. In each drawing, an arrow H indicates the vertical direction, and an arrow W indicates the horizontal direction, ie, the width direction of the device.

[0017] <Configuration of Image Forming Apparatus 10> 1 is a schematic diagram showing the configuration of an image forming apparatus 10 as viewed from the front side. As shown in this figure, the image forming apparatus 10 has an image forming unit 12 that forms an image on a recording medium P such as paper by electrophotography, a conveying device 50 that conveys the recording medium P, and a control unit 70 that controls the operation of each part of the image forming apparatus 10.

[0018] (Transportation device 50) 1, the transport device 50 has a container 51 that stores the recording medium P, and a plurality of transport rolls 52 that transport the recording medium P from the container 51 to a secondary transfer position NT. The transport device 50 further has a plurality of transport belts 58 that transport the recording medium P from the secondary transfer position NT to the fixing device 40, and a transport belt 54 that transports the recording medium P from the fixing device 40 to a discharge section (not shown) for the recording medium P.

[0019] (Image forming unit 12) The image forming section 12 has a toner image forming section 20 that forms a toner image, a transfer device 30 that transfers the toner image formed in the toner image forming section 20 to a recording medium P, and a fixing device 40 that heats and pressurizes the toner image transferred to the recording medium P to fix it to the recording medium P.

[0020] A plurality of toner image forming units 20 are provided so as to form a toner image for each color. In this embodiment, toner image forming units 20 for a total of four colors, yellow (Y), magenta (M), cyan (C), and black (K), are provided. The toner image forming units 20 for each color are arranged in the order of yellow (Y), magenta (M), cyan (C), and black (K) from the upstream side to the downstream side in the transport direction of an intermediate transfer belt 31 described later.

[0021] In Fig. 1, (Y), (M), (C), and (K) indicate components corresponding to the above-mentioned respective colors. In the explanation of this specification, the parentheses of (Y), (M), (C), and (K) may be omitted and the components may be written as Y, M, C, and K.

[0022] [Toner image forming unit 20] The toner image forming units 20 of each color are basically configured in the same manner except for the toner used. Specifically, as shown in Fig. 2, the toner image forming units 20 of each color include a photoconductor drum 21 that rotates in a clockwise direction in Fig. 2, a charger 22 that charges the photoconductor drum 21, and an exposure device 23 that exposes the photoconductor drum 21 charged by the charger 22 to form an electrostatic latent image on the photoconductor drum 21. Furthermore, the toner image forming units 20 of each color include a developing device 24 that develops the electrostatic latent image formed on the photoconductor drum 21 by the exposure device 23 to form a toner image, and a blade 25 that removes toner remaining on the surface of the photoconductor drum 21 after the toner image is transferred to the transfer device 30.

[0023] The charger 22 charges the surface (photosensitive layer) of the photoconductor drum 21 to a negative polarity, for example. The negatively charged surface of the photoconductor drum 21 has a positive polarity at a portion irradiated with exposure light L by the exposure device 23, and an electrostatic latent image is formed on the surface of the photoconductor drum 21. Then, the toner that has been frictionally charged to a negative polarity in the developing device 24 adheres to the electrostatic latent image that has a positive polarity, and the electrostatic latent image is developed. In this manner, a toner image is formed on the surface (outer peripheral surface) of the photoconductor drum 21. The blade 25 comes into contact with the surface of the photoconductor drum 21 and scrapes off the toner remaining on the surface of the photoconductor drum 21.

[0024] [Transfer device 30] The transfer device 30 performs primary transfer of the toner images of the photoconductor drums 21 of each color in a superimposed manner onto the intermediate transfer belt 31, and then performs secondary transfer of the superimposed toner images onto the recording medium P at a secondary transfer position NT (an example of a nip). Specifically, as shown in Fig. 1, the transfer device 30 includes an intermediate transfer belt 31 which is an example of an endless belt and an example of a toner transport body which is a transfer body, a primary transfer roll 33, a secondary transfer belt 36 which is an example of a toner transport body which is a transfer body, a cleaning device 60 for the secondary transfer belt 36, and a cleaning device 35 for the intermediate transfer belt 31.

[0025] [Intermediate transfer belt 31] As shown in Fig. 1, the intermediate transfer belt 31 is endless and is wound around a plurality of rolls 32 to determine its position. In this embodiment, the intermediate transfer belt 31 is oriented in the shape of an inverted obtuse triangle that is long in the width direction of the device when viewed from the front. Of the plurality of rolls 32, roll 32D shown in Fig. 1 functions as a drive roll that rotates the intermediate transfer belt 31 in the direction of arrow A by the power of a motor (not shown). By rotating in the direction of arrow A, the intermediate transfer belt 31 transports the primarily transferred image to a secondary transfer position NT.

[0026] 1 functions as a tension applying roll that applies tension to the intermediate transfer belt 31. Of the multiple rolls 32, roll 32B shown in FIG. 1 functions as an opposing roll for the secondary transfer roll 34. The apex of the lower end side forming the obtuse angle of the intermediate transfer belt 31, which is oriented in an inverted obtuse triangle shape as described above, is wound around the opposing roll 32B. This intermediate transfer belt 31 contacts the photoconductor drums 21 of each color from below at its upper side extending in the device width direction in the above-described orientation.

[0027] [Primary transfer roll 33] 1, the primary transfer roll 33 is a roll that transfers the toner image of each photoconductor drum 21 to the intermediate transfer belt 31, and is disposed inside the intermediate transfer belt 31. Each primary transfer roll 33 is disposed facing the photoconductor drum 21 of the corresponding color across the intermediate transfer belt 31. A primary transfer voltage of a polarity opposite to the toner polarity is applied to the primary transfer roll 33 by a power supply unit (not shown). By applying this primary transfer voltage, the toner image formed on the photoconductor drum 21 is transferred to the intermediate transfer belt 31 at a primary transfer position T between the photoconductor drum 21 and the primary transfer roll 33.

[0028] [Secondary transfer belt 36] The secondary transfer belt 36 is a belt that transfers the toner image superimposed on the intermediate transfer belt 31 to the recording medium P. As shown in FIG. 3, the secondary transfer belt 36 is endless and is wound around the secondary transfer roll 34 and the driven roll 37.

[0029] The secondary transfer roll 34 is disposed so as to sandwich the intermediate transfer belt 31 and the secondary transfer belt 36 between it and the opposing roll 32B, and the secondary transfer belt 36 and the intermediate transfer belt 31 are in contact with each other with a predetermined load. The space between the secondary transfer belt 36 and the intermediate transfer belt 31 in this manner is defined as the secondary transfer position NT. A recording medium P is supplied to this secondary transfer position NT from a container 51 at an appropriate time. The secondary transfer belt 36 is moved in a circular motion in the direction of the arrow B by the secondary transfer roll 34 being driven to rotate.

[0030] In this embodiment, when the toner image on the intermediate transfer belt 31 is transferred to the recording medium P, a negative voltage is applied to the opposing roll 32B by the power supply unit 39. This generates a potential difference between the opposing roll 32B and the secondary transfer roll 34. That is, by applying a negative voltage to the opposing roll 32B, a secondary transfer voltage (positive voltage) of the opposite polarity to the toner polarity is indirectly applied to the secondary transfer roll 34 that serves as the opposing electrode of the opposing roll 32B. This causes the negative toner image to be transferred from the intermediate transfer belt 31 to the recording medium P that passes through the secondary transfer position NT.

[0031] On the other hand, when the toner on the intermediate transfer belt 31 passes through the secondary transfer position NT, in order to hold the toner on the intermediate transfer belt 31, a positive voltage is applied to the opposing roll 32B by the power supply unit 39. This generates a potential difference between the opposing roll 32B and the secondary transfer roll 34. That is, by applying a positive voltage to the opposing roll 32B, a non-transfer voltage (negative voltage) of the same polarity as the toner polarity is indirectly applied to the secondary transfer roll 34, which serves as the opposing electrode of the opposing roll 32B. As a result, the toner passing through the secondary transfer position NT is subjected to a repulsive force from the secondary transfer roll 34 and is held on the intermediate transfer belt 31.

[0032] [Cleaning device 60 for secondary transfer belt 36] As shown in FIG. 3, the cleaning device 60 has a cleaning brush 61 that comes into contact with the secondary transfer belt 36 and cleans the secondary transfer belt 36 by attracting toner thereon with electrostatic force corresponding to an applied bias voltage. The cleaning brush 61 is an example of a toner attracting member, and is a cylindrical roll brush that is an example of a brush that comes into contact with a toner transport body. As an example, the cleaning brush 61 is provided at a portion where the secondary transfer belt 36 is wrapped around the secondary transfer roll 34 . It should be noted that "cleaning the toner adhering to the belt" is synonymous with "removing the toner from the belt."

[0033] The cleaning brush 61 has a metal shaft portion 61A and a synthetic resin brush portion 61B provided around the entire outer periphery of the shaft portion 61A. In the brush portion 61B, a large number of first bristles 61F extend radially (outward in the radial direction) from the shaft portion 61A. The cleaning brush 61 rotates when the shaft 61A is rotated by a first rotation drive device 67 including a motor, a reducer, etc. (not shown). The cleaning brush 61 rotates in the same direction as the rotation direction of the secondary transfer belt 36 (clockwise in FIG. 3), for example.

[0034] The rotary drive device 67 can also rotate the cleaning brush 61 in a direction opposite to the rotation direction of the secondary transfer belt 36 (counterclockwise in FIG. 3). When the cleaning brush 61 rotates in a direction opposite to the rotation direction of the secondary transfer belt 36, the cleaning brush 61 is configured to rotate at a peripheral speed different from that of the secondary transfer belt 36, for example.

[0035] The cleaning device 60 has a power supply unit 65 that applies a positive bias voltage (cleaning voltage) to the shaft 61A of the cleaning brush 61.

[0036] The cleaning device 60 has a cylindrical flicking bar 63 that comes into contact with the brush portion 61B of the cleaning brush 61 to repel the first bristles 61F. Note that the flicking bar 63 is not limited to the flicking bar 63, and may be another member such as a roll-shaped brush, as long as it can remove toner from the cleaning brush 61.

[0037] Furthermore, in the cleaning device 60, a film 68 as an example of a charge applying member is provided upstream of the cleaning brush 61 in the rotation direction of the secondary transfer belt 36 and downstream of the secondary transfer position NT so as to face the outer circumferential surface of the secondary transfer belt 36. In this embodiment, the film 68 is disposed below the driven roll 37 and provided so that a tip portion thereof contacts the outer circumferential surface of the secondary transfer belt 36. Note that, as an example, the film 68 is provided at a portion where the secondary transfer belt 36 is wound around the driven roll 37.

[0038] In the image forming apparatus 10 of the present embodiment, as an example, the secondary transfer belt 36 is made of a rubber material, and the film 68 is made of a resin material. The resin material forming the film 68 is a resin material that, in terms of the electrostatic charge series, rubs against the secondary transfer belt 36 and more easily imparts a negative charge to the toner than the material (rubber material) constituting the secondary transfer belt 36. For this reason, when the film 68 is brought into contact with the toner adhering to the surface of the secondary transfer belt 36, the negative charge of the toner in contact with the film 68 can be increased.

[0039] Examples of the resin material that can be used to form the film 68 include polyurethane, polyethylene, polyimide, and polystyrene, but other resin materials may also be used as long as they are easier to impart a negative charge to the toner than the material that forms the secondary transfer belt 36.

[0040] The cleaning device 60 is provided with a blade 69, which is disposed downstream of the cleaning brush 61 in the rotational direction of the secondary transfer belt 36 and upstream of the secondary transfer position NT, for scraping off residual toner from the surface of the secondary transfer belt 36.

[0041] In addition, the cleaning device 60 is provided with a receiver 71 between the secondary transfer belt 36 so as to surround the cleaning brush 61, the flicking bar 63, and the blade 69, and is configured so that the toner removed from the secondary transfer belt 36 falls into the receiver 71.

[0042] [Cleaning device 35 for intermediate transfer belt 31] 1, the cleaning device 35 is disposed downstream of the secondary transfer position NT and upstream of the primary transfer position T(Y) in the rotation direction of the intermediate transfer belt 31. The cleaning device 35 includes a blade 351 that scrapes off residual toner from the surface of the intermediate transfer belt 31.

[0043] In the transfer device 30, a detection unit (sensor) 49 for detecting density detection images (patches) and color shift detection images (patches) is arranged downstream (left side in FIG. 1) of the toner image forming unit 20(K).

[0044] The toners of yellow (Y), magenta (M), cyan (C), and black (K) used in the toner image forming units 20Y, 20M, 20C, and 20K (hereinafter referred to as 20Y to 20K) contain a pigment and a binder resin.

[0045] The toner images formed by the toner image forming units 20Y to 20K include transfer images for transferring onto the recording medium P and non-transfer images that are not transferred onto the recording medium P. The non-transfer images include images (patches) for detecting density, images (patches) for detecting color misregistration, images (bands) for consuming deteriorated developer (toner), images (bands) for supplying toner between the photoconductor drum 21 and the blade 25, and the like.

[0046] 4, the image 320 of each toner image forming unit 20 is transferred to a transfer region R1 on the intermediate transfer belt 31 by each primary transfer roll 33. The image 320 transferred to the intermediate transfer belt 31 passes through a secondary transfer position NT together with the recording medium P and is transferred to the recording medium P.

[0047] On the other hand, the patch 420 of each toner image forming unit 20 is transferred to a non-transfer area R2 between the transfer areas R1 by each primary transfer roll 33. The patch 420 transferred onto the intermediate transfer belt 31 passes through the secondary transfer position NT by itself, without passing through the secondary transfer position NT together with the recording medium P.

[0048] In this embodiment, when the image 320 is transferred from the intermediate transfer belt 31 to the recording medium P, as described above, a positive secondary transfer voltage (a voltage having a polarity opposite to that of the toner polarity) is applied to the secondary transfer roll 34 via the opposing roll 32B. This causes the image 320, which passes through the secondary transfer position NT together with the recording medium P, to be transferred from the intermediate transfer belt 31 to the recording medium P.

[0049] On the other hand, when the patch 420 passes through the secondary transfer position NT, a negative non-transfer voltage (a voltage with the same polarity as the toner polarity) is applied to the secondary transfer roll 34 via the opposing roll 32B so that the patch 420 on the intermediate transfer belt 31 is retained on the intermediate transfer belt 31.

[0050] As a result, the toner of the patch 420 on the intermediate transfer belt 31 receives a repulsive force from the secondary transfer belt 36 (secondary transfer roll 34) and is held on the intermediate transfer belt 31. The toner of the patch 420 held on the intermediate transfer belt 31 is transported to the cleaning device 35 and removed from the intermediate transfer belt 31 by the cleaning device 35.

[0051] Here, since the secondary transfer belt 36 and the intermediate transfer belt 31 are in contact with each other with a predetermined load, when the patch 420 is formed on the surface of the intermediate transfer belt 31, a part of the toner of the patch 420 is transferred to the secondary transfer belt 36 even when subjected to electrostatic repulsion. When the toner of the patch 420 is transferred to the secondary transfer belt 36, the toner adheres to the secondary transfer belt 36 (an example of a transfer member).

[0052] (Action according to this embodiment) Next, the operation of this embodiment will be described.

[0053] When the control unit 70 receives an image formation command (print command), the control unit 70 operates the toner image forming units 20Y to 20K, the transfer device 30, and the fixing device 40 as follows (see FIG. 1).

[0054] In the toner image forming units 20Y to 20K, an image 320 (see FIG. 4) and a patch 420 (see FIG. 4) are formed in the following image forming process. That is, the photoconductor drum 21 of each color is charged by the charger 22 while rotating. Each charged photoconductor drum 21 is exposed by each exposure device 23, and an electrostatic latent image is formed on the surface of each photoconductor drum 21. The electrostatic latent image formed on each photoconductor drum 21 is developed by a developer supplied from the development device 24. As a result, images 320 and patches 420 of yellow (Y), magenta (M), cyan (C), and black (K) are formed on the photoconductor drums 21Y to 21K for the other colors, respectively.

[0055] As shown in FIG. 4, the images 320 of the respective colors formed on the respective photoconductor drums 21 are sequentially transferred by the respective primary transfer rolls 33 to a transfer region R1 of the rotating intermediate transfer belt 31.

[0056] Furthermore, the patches 420 of each color formed on each photoconductor drum 21 are sequentially transferred by each primary transfer roll 33 to an arbitrary position in the non-transfer region R2 of the rotating intermediate transfer belt 31.

[0057] The image 320 transferred onto the intermediate transfer belt 31 is transported to the secondary transfer position NT by the rotation of the intermediate transfer belt 31.

[0058] The recording medium P is supplied to this secondary transfer position NT by the transport roll 52 in accordance with the timing of transport of the image 320. When the recording medium P and the image 320 (transfer region R1) pass through this secondary transfer position NT, a secondary transfer voltage (a voltage of positive polarity) is applied to the secondary transfer roll 34 via the opposing roll 32B. As a result, the image 320 is transferred from the intermediate transfer belt 31 to the recording medium P.

[0059] The recording medium P onto which the image 320 has been transferred is transported by the transport belt 58 from the secondary transfer position NT to the fixing device 40, where the image 320 on the recording medium P is fixed to the recording medium P.

[0060] When the patch 420 passes the secondary transfer position NT without the recording medium P passing through it, a non-transfer voltage (a voltage of negative polarity) is applied to the secondary transfer roll 34 via the opposing roll 32B. As a result, the patch 420 on the intermediate transfer belt 31 receives a repulsive force from the secondary transfer roll 34 (secondary transfer belt 36) and is held on the intermediate transfer belt 31. As a result, the toner of the patch 420, while being held on the intermediate transfer belt 31, passes through the secondary transfer position NT and is transported to the cleaning device 35, and is removed from the intermediate transfer belt 31 by the cleaning device 35.

[0061] Although a non-transfer voltage is applied in this manner, the secondary transfer belt 36 and the intermediate transfer belt 31 are in contact with each other at a predetermined load, so that some of the toner of the patch 420 may be transferred to the secondary transfer belt 36 even when subjected to electrostatic repulsion force.

[0062] In this embodiment, the toner transferred to the secondary transfer belt 36 is transported to the cleaning device 60 as the secondary transfer belt 36 rotates. Note that the toner of the image 320 may adhere to the secondary transfer belt 36. The toner adhering to the secondary transfer belt 36 is not limited to toner with a high charge amount, but also includes toner with a low charge amount.

[0063] The toner adhered to the secondary transfer belt 36 moves downstream in the transport direction (arrow B direction) of the secondary transfer belt 36 from the secondary transfer position NT due to the circular movement of the secondary transfer belt 36. In addition, as the secondary transfer belt 36 circularly moves, the film 68 slides against the surface of the secondary transfer belt 36 and is frictionally charged to a negative polarity.

[0064] When the toner adhering to the secondary transfer belt 36 and being transported comes into contact with the film 68 thus negatively charged by friction, the toner is charged with a negative charge, increasing the negative charge. Therefore, even if toner with a small charge is transported, the charge of the toner is increased by coming into contact with the film 68.

[0065] In the cleaning device 60, a positive voltage is applied to the cleaning brush 61 by the power supply unit 65, but the toner on the secondary transfer belt 36 transported to the cleaning device 60 has its negative charge increased by the film 68, so that a large potential difference is generated between the toner and the cleaning brush 61. Therefore, compared to the case where the toner is electrostatically attracted as is, a large suction force acts on the cleaning brush 61 side, which is the downstream toner attracting member to which a voltage of the opposite polarity is applied, and the cleaning brush 61 can efficiently attract and remove the toner.

[0066] In this embodiment, the resin material forming the film 68 is more easily charged to the negative polarity than the resin material forming the secondary transfer belt 36. Therefore, it is easier to impart a negative charge to the toner than when the resin material forming the secondary transfer belt 36 and the resin material forming the film 68 have the same charge series. As an example, if the film 68 is formed from any of the resin materials polyurethane, polyethylene, polyimide, and polystyrene, it is easier to charge the toner and attract the toner than when the film 68 is formed from a rubber material.

[0067] In the cleaning device 60 of this embodiment, a large number of bristles 61F of the cleaning brush 61 are brought into contact with the secondary transfer belt 36, so that the toner adhering to the secondary transfer belt 36 can be mechanically peeled off more easily than when the toner is adsorbed by a detoning roll, which is an electrostatic adsorption member.

[0068] The bristles 61F of the cleaning brush 61 are repelled by the flicking bar 63, so that the toner adhering to the bristles 61F separates from the bristles 61F and falls into the receiver 71.

[0069] Moreover, if the cleaning brush 61 is unable to completely remove the toner from the secondary transfer belt 36 and some of the toner remains, the toner is removed by the blade 69 on the downstream side.

[0070] 3B, the film 68 may be provided with an abrasion-resistant layer 68A, which has better abrasion resistance than the resin material forming the film 68, at the tip portion that contacts the secondary transfer belt 36. As an example of the material for the abrasion-resistant layer 68A, diamond-like carbon may be used, but other materials may also be used. By providing the abrasion-resistant layer 68A on the film 68, the abrasion resistance of the film 68 can be improved.

[0071] [Other embodiments] Although one embodiment of the present invention has been described above, the present invention is not limited to the above, and it goes without saying that the present invention can be implemented in various modified forms without departing from the spirit and scope of the present invention.

[0072] In the above embodiment, the blade 69 is provided downstream of the cleaning brush 61, but the blade 69 may be provided as needed and is not necessarily required.

[0073] In the above embodiment, the cleaning brush 61, which is a roll brush, is used as an example of a toner attracting member, but as long as it can attract charged toner, a brush with bristles on a flat plate may be used, and it does not have to be a cylindrical roll brush. Also, instead of the cleaning brush 61, a detoning roll, which is an electrostatic attraction member, may be used.

[0074] In the above embodiment, the cleaning device 60 is used to clean the secondary transfer belt 36, but the cleaning device 60 can also be used to clean the intermediate transfer belt 31. In this case, although not shown in the drawings, the cleaning device 60 can be used instead of the cleaning device 35. This allows the cleaning device 60 to clean the toner adhering to the intermediate transfer belt 31, similar to the secondary transfer belt 36.

[0075] In the case of an image forming apparatus that does not have a secondary transfer belt 36 and has a configuration in which the recording medium P is nipped between the secondary transfer roll 34 and the intermediate transfer belt 31, the secondary transfer roll 34 serves as the toner transport body of the present invention. In this case, although not shown in the drawings, a cleaning device 60 may be provided opposite the secondary transfer roll 34, so that the toner adhering to the secondary transfer roll 34 can be cleaned by the cleaning device 60. [Explanation of symbols]

[0076] 10 Image forming device 31 Intermediate transfer belt (an example of an endless belt, an example of a toner transport body that is a transfer member) 36 Secondary transfer belt (an example of a toner transport body that is a transfer member) P Recording medium 61 Roll brush (an example of a toner attracting member) 68 Film (an example of a charge-imparting material) 68A Abrasion resistant layer

Claims

1. a toner conveying member which is an endless belt for holding a toner image or a transfer member which transfers the toner image to a recording medium nipped between the endless belt and the toner conveying member; a charge applying member provided opposite to a surface of the toner transport body and configured to increase the charge of the toner adhering to the surface of the toner transport body; a toner attracting member that is provided downstream of the charge applying member in the transport direction of the toner transport body and that attracts the toner by applying a voltage of a polarity opposite to that of the toner adhering to the surface of the toner transport body; having the charge-giving member is frictionally charged by the sliding caused by the rotational movement of the toner transport body, the triboelectrically charged charge-giving member increases the charge of the toner with which it comes into contact; Image forming device.

2. A toner conveying body which is an endless belt for holding a toner image or a transfer member for transferring a toner image to a recording medium nipped between said endless belt and said toner conveying body; a charge applying member provided opposite to a surface of the toner transport body and configured to increase the charge of the toner adhering to the surface of the toner transport body; a toner attracting member that is provided downstream of the charge applying member in the transport direction of the toner transport body and that attracts the toner by applying a voltage of a polarity opposite to that of the toner adhering to the surface of the toner transport body; having the charge applying member is provided so as to slide against the toner on the moving toner transport body, and is a film made of a resin material that is more likely to apply a negative charge to the toner than a material constituting the toner transport body; Image forming device.

3. The film is formed of any one of polyurethane, polyethylene, polyimide, and polystyrene. The image forming apparatus according to claim 2 .

4. A toner conveying body which is an endless belt for holding a toner image or a transfer member for transferring a toner image to a recording medium nipped between said endless belt and said toner conveying body; a charge applying member provided opposite to a surface of the toner transport body and configured to increase the charge of the toner adhering to the surface of the toner transport body; a toner attracting member that is provided downstream of the charge applying member in the transport direction of the toner transport body and that attracts the toner by applying a voltage of a polarity opposite to that of the toner adhering to the surface of the toner transport body; having a wear-resistant layer made of a material having a higher wear resistance than a material constituting the charge-giving member is provided at a portion of the charge-giving member that comes into contact with the toner transport body; Image forming device.

5. The wear-resistant layer is made of diamond carbon. The image forming apparatus according to claim 4 .

6. The toner attracting member is a roll brush that contacts the toner transport body. The image forming apparatus according to any one of claims 1 to 5.

Images