JP2007334011A - Cleaner and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent toner stains on the secondary transfer roller 56 so as not cause staining of the back surface of the transfer material S, in an image forming device 100 that repeatedly forms control images G on an intermediate transfer belt 51. <P>SOLUTION: The image forming device 100 forms control images G for each space between the sheets carried on the intermediate transfer belt 51. A secondary transfer section cleaner 7 is provided to exclusively clean the secondary transfer roller 56. The control images, adhering on the secondary transfer roller 56, are electrically attracted from the fur brush 71 and moved to the metal roller 72 and are then scraped off by the cleaning blade 73 down into the waste toner container 74. The cleaning voltage supply 75 outputs 180 V to enhance the cleaning power of the secondary transfer roller 56 with the timing of the control images G pass the fur brush 71. However, the device applies 280 V one step higher, first to prioritize moving the toner from the fur brush 71 to the metal roller 72 between the control images G. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cleaning device that electrically removes toner by adsorbing and moving it from an adhesion surface, and more particularly, to control of an applied voltage related to electrostatic attraction and moving, and also to an image forming apparatus equipped with the cleaning device.

  2. Description of the Related Art Image forming apparatuses such as copying machines, printers, and printing machines that form a plurality of primary color toner images using an electrophotographic process to form a color image on a transfer material have been put into practical use. As an example of a high-productivity model for forming a color image, a tandem image forming apparatus in which a plurality of photosensitive drums having different development colors are arranged in a line along an intermediate transfer belt has been put into practical use (see FIG. 1). Further, a fur brush type cleaning device has been put to practical use as an example in which unnecessary toner adhering to an image carrier such as a photosensitive drum and an intermediate transfer belt is removed by electrically adsorbing and moving (FIG. 2). reference).

  Patent Document 1 discloses a tandem image forming apparatus in which a secondary transfer roller and an intermediate transfer belt form a secondary transfer nip, and a toner image primarily transferred onto the intermediate transfer belt is secondarily transferred onto a transfer material. Indicated. Here, a control toner image is formed at the image forming interval (inter-paper space) of the intermediate transfer belt, and the density detection result of the control toner image is fed back to the image forming conditions of each color using the photosensitive drum.

  Here, the used control toner image whose density has been detected is desirably removed by a downstream cleaning device after passing through the secondary transfer nip where the secondary transfer roller is separated. If the secondary transfer roller is kept in pressure contact with the intermediate transfer belt, a control toner image that is not transferred onto the transfer material will adhere to the secondary transfer roller, and the control toner image will show through on the transfer material. . This is because when the secondary transfer nip is kept in pressure contact and the toner adheres to the secondary transfer roller, a dedicated cleaning device for removing the toner from the secondary transfer roller is required.

  Patent Document 2 discloses a cleaning device that removes toner adhering to a secondary transfer roller by an insulating rotating brush that is driven to rotate and contacts the secondary transfer roller. The rotating brush rotates at high speed, and the surface of the secondary transfer roller is softly rubbed to mechanically scrape off the toner.

  Patent Document 3 discloses a cleaning device that electrically removes toner adhered to an intermediate transfer belt by a conductive fur brush that is driven to rotate and contacts the intermediate transfer belt. The conductive fur brush is in contact with the rotating metal roller to which the cleaning voltage is applied, and the toner adhering to the intermediate transfer belt is received from the conductive fur brush to the metal roller by the electrostatic adsorption force of the cleaning voltage. Passed. The toner delivered to the metal roller is finally mechanically separated and collected from the metal roller by a cleaning blade that slides on the metal roller.

JP 2006-126448 A JP 2000-187405 A JP 2002-229344 A

  The tandem image forming apparatus is required to frequently adjust the color balance by frequently detecting the control toner image in order to improve color reproducibility. Further, while the circulation speed of the intermediate transfer belt is increased in order to increase productivity, it is not permitted to increase the image forming interval even when the control toner image is formed frequently. Therefore, it is difficult to prevent the toner from adhering to the secondary transfer roller by separating the secondary transfer roller from the intermediate transfer belt every time the control toner image passes. If the secondary transfer roller repeatedly presses / separates at a high speed, there is a possibility of causing problems in vibration generation and stable running of the intermediate transfer belt.

  In view of this, it has been proposed to employ the electrical cleaning device disclosed in Patent Document 3 in combination with the cleaning device dedicated to the secondary transfer roller disclosed in Patent Literature 2. The cleaning device using the conductive fur brush can efficiently remove the toner at every corner with a lower rubbing pressure than the mechanical rubbing disclosed in Patent Document 2, and the toner scattering due to the rotation is small. It is.

  However, when the cleaning device of Patent Document 3 is used for a long period of time, toner accumulates on the conductive fur brush, and the amount of toner that moves back to the toner adhesion surface (secondary transfer roller surface) increases, and the cleaning performance gradually decreases.

  Therefore, it has been studied to increase the cleaning voltage applied to the metal roller and increase the amount of toner delivered from the conductive fur brush to the metal roller, thereby delaying the toner accumulation of the conductive fur brush. However, it has been found that when the cleaning voltage applied to the metal roller is increased, the cleaning efficiency with which the essential conductive fur brush removes the toner from the toner adhesion surface decreases (see FIG. 5).

  SUMMARY OF THE INVENTION An object of the present invention is to provide a cleaning device that can maintain high cleaning efficiency of a toner adhesion surface over a long period of time. An object of the present invention is to provide a cleaning device capable of efficiently transferring toner from the conductive fur brush to the metal roller without impairing the performance of the conductive fur brush to remove the toner from the surface of the secondary transfer roller. An object of the present invention is to provide an image forming apparatus capable of preventing the backside contamination of a transfer material through a secondary transfer roller for a long period of time even when a control toner image is formed frequently.

  The cleaning device of the present invention has a first cleaning member that is conductive and circulates in contact with the toner adhesion surface, and a circulation position that has conductivity and the first cleaning member does not contact the adhesion surface. A second cleaning member in contact with the first cleaning member, a removing means for removing toner attached to the second cleaning member via the first cleaning member, and applying a voltage to the second cleaning member. And a power supply means for charging the first cleaning member. The power supply means can apply a second cleaning voltage to the second cleaning member, which is different from the first cleaning voltage when removing toner from the adhesion surface. The second cleaning voltage is set to a voltage value that prioritizes the movement of toner from the first cleaning member to the second cleaning member over the movement of toner from the attachment surface to the first cleaning member. .

  An image forming apparatus according to the present invention includes an image carrier that carries an image toner image, a transfer member that forms a transfer nip between the image carrier and transfers the image toner image to a transfer material, Detection means for optically detecting the control toner image carried on the image carrier, and the control toner image carried on the interval between the image toner images carried on the image carrier by the detection means And a control means for detection. 6. The cleaning device according to claim 3, wherein the first cleaning member is brought into contact with the transfer member. The control means controls the power supply means to output the first cleaning voltage and the second cleaning voltage in correspondence with the movement position of the control toner image carried on the image carrier.

  In the cleaning device of the present invention, the second cleaning voltage is applied in a time-sharing manner during the image forming cycle, and the movement of the toner from the first cleaning member to the second cleaning member is made efficient. That is, at the timing when the necessity of removing the toner from the adhesion surface is low, the maximum efficiency of removing the toner from the first cleaning member can be exhibited by the second cleaning voltage ignoring the cleaning effect on the adhesion surface.

  In other words, if there is no toner to be removed on the adhesion surface, the toner accumulated in the first cleaning member can be positively removed using the second cleaning voltage. Thus, at the timing when there is toner to be removed on the next adhering surface, the first cleaning member with a small amount of toner accumulation can be used for efficient cleaning with less toner going back to the adhering surface.

  Therefore, the cleaning efficiency of the adhesion surface can be maintained high over a long period of time while repeating the image forming cycle in which the toner to be removed adheres to the adhesion surface intermittently. For example, the toner can be efficiently transferred from the conductive fur brush to the metal roller without impairing the ability of the conductive fur brush to remove the toner from the surface of the secondary transfer roller.

  The image forming apparatus of the present invention employs such a cleaning device, so that even when a control toner image is frequently formed on the image carrier, the backside contamination of the transfer material through the transfer member is extended over a long period of time. Can be prevented. For example, the control toner image attached to the secondary transfer roller from the intermediate transfer belt can be efficiently removed by the conductive fur brush, and the toner accumulation of the conductive fur brush can be suppressed to prevent the transfer material from being stained for a long period of time. .

  Hereinafter, an image forming apparatus 100 according to an embodiment of the present invention will be described in detail with reference to the drawings. The image forming apparatus of the present invention is not limited to the limited configuration of the embodiments described below. As long as the toner adhering to the secondary transfer roller and the like is electrically adsorbed and removed by the cleaning device, it can be realized in another embodiment in which a part or all of the configuration of each embodiment is replaced with the alternative configuration. It is.

  In this embodiment, a cleaning device for a secondary transfer roller of a tandem type image forming apparatus will be described. However, the cleaning device of the present invention can also be implemented as a toner image carrier cleaning device such as a photosensitive drum or an intermediate transfer belt.

  The cleaning device of the present invention is not limited to the tandem image forming device, and a plurality of developing devices having different developing colors are arranged around the photosensitive drum, and a color image is formed by sequentially superimposing a plurality of color toner images on the intermediate transfer belt. It can be mounted on an image forming apparatus to be formed. It can also be mounted on an image forming apparatus or the like that directly transfers a single color toner image formed on a photosensitive drum to a transfer material. The image forming apparatus of the present invention is not limited to a printer, and can be implemented as an image forming apparatus for various uses such as various printing machines, copiers, FAX machines, and multifunction machines.

  The configuration of the image forming apparatus and the detailed structure and operation of the cleaning apparatus disclosed in Patent Documents 1 to 3 are not illustrated and detailed description is omitted to avoid repeated complications.

<First Embodiment>
[Entire configuration of image forming apparatus]
FIG. 1 is an explanatory diagram of a schematic configuration of the image forming apparatus according to the first embodiment, FIG. 2 is an explanatory diagram of an arrangement of control images, and FIG. 3 is an explanatory diagram of a configuration around a secondary transfer unit. As shown in FIG. 1, the image forming apparatus 100 according to the first embodiment is a full-color printer that can form a full-color image on a transfer material (plain paper, OHP sheet, etc.) S by electrophotography in accordance with an image signal. The image signal is transmitted to the control unit 110 of the apparatus main body 100A from an external device such as a personal computer (not shown), an image reading apparatus, and a digital camera that are communicably connected to the apparatus main body 100A.

  The image forming apparatus 100 is a tandem type image forming apparatus in which four image forming portions Pa, Pb, Pc, and Pd are arranged in series along the horizontal portion of the intermediate transfer belt 51. The configuration of each image forming unit Pa, Pb, Pc, Pd is the same except for the color of the toner to be used. Accordingly, in the following, when there is no particular need to distinguish, subscripts a, b, c, and d attached to the reference numerals to indicate that they are elements provided for any color will be omitted, and a general description will be given. To do.

  The image forming unit P includes a photosensitive drum 1 that is a drum-shaped electrophotographic photosensitive member that is rotationally driven in the direction of an arrow (counterclockwise). Around the photosensitive drum 1, process equipment such as a charging roller 2 as a primary charging unit, an exposure device 3 as an exposure unit, a developing device 4 as a developing unit, and a cleaning unit 6 as a cleaning unit are arranged. Yes.

  The developing devices 4a to 4d disposed in the image forming portions Pa to Pd include two-component developers containing toners of yellow (Y), magenta (M), cyan (C), and black (Bk), respectively. Is stored. Each of the image forming units Pa to Pd forms a toner image of each color of yellow, magenta, cyan, and black.

  The intermediate transfer unit 5 arranged to face the photosensitive drums 1a to 1d of the image forming portions Pa to Pd has an intermediate transfer belt 51 as an intermediate transfer member. The intermediate transfer belt 51 is an endless elastic belt that is stretched around a driving roller 52, a tension roller 53, a backup roller 54, and the like, and a driving force is transmitted to the driving roller 52 in an arrow direction (clockwise). Circulate.

  A primary transfer roller 55 is disposed on the inner peripheral surface side of the intermediate transfer belt 51 at a position facing the photosensitive drum 1 of each image forming unit P. Each primary transfer roller 55 presses the intermediate transfer belt 51 toward the photosensitive drum 1, thereby forming primary transfer nips N <b> 1 a to N <b> 1 d where the intermediate transfer belt 51 contacts the photosensitive drum 1.

  A secondary transfer roller 56 is disposed at a position facing the backup roller 54 with the intermediate transfer belt 51 interposed therebetween. The secondary transfer roller 56 is in pressure contact with the backup roller 54 via the intermediate transfer belt 51, and forms a secondary transfer nip N <b> 2 between the intermediate transfer belt 51 and the secondary transfer roller 56.

  In the image forming apparatus 100 configured as described above, at the time of forming a full-color image, first, in the first image forming portion Pa, the photosensitive drum 1a is uniformly charged by the charging roller 2a. On the charged photosensitive drum 1a, light corresponding to the image signal of the yellow component color of the original is projected from the exposure device 3a through a polygon mirror or the like. Thereby, an electrostatic latent image corresponding to the image signal of the yellow component color is formed on the photosensitive drum 1a. Next, the electrostatic latent image on the photosensitive drum 1a is developed as a yellow toner image by supplying yellow toner from the developing device 4a. When the toner image reaches the primary transfer nip N1a as the photosensitive drum 1a rotates, the toner image is primarily transferred to the intermediate transfer belt 51 by the primary transfer roller 55a. At this time, a predetermined primary transfer bias having a polarity opposite to the normal charging polarity of the toner is applied to the primary transfer roller 55a from the primary transfer bias power source.

  The intermediate transfer belt 51 carrying the yellow toner image is conveyed to the next second image forming unit Pb. By this time, a magenta toner image has been formed on the photosensitive drum 1b by the same method as described above in the second image forming portion Pb. This magenta toner image is superimposed and transferred onto the yellow toner image on the intermediate transfer belt 51 in the primary transfer nip N1b in the same manner as described above.

  Similarly, as the intermediate transfer belt 51 proceeds to the third and fourth image forming portions Pc and Pd, the cyan toner image and the black toner image are respectively transferred to the toner on the intermediate transfer belt 51 at the primary transfer nips N1c and N1d. It is superimposed and transferred to the image.

  On the other hand, the transfer material S is sent out from the cassette 91 of the transfer material supply unit 9, and is supplied to the secondary transfer nip N2 in synchronization with the toner image on the intermediate transfer belt 51. The four color toner images on the intermediate transfer belt 51 are moved by being urged by the electric field formed between the backup roller 54 and the secondary transfer roller 56 in the secondary transfer nip N2, and onto the transfer material S. Secondary transferred. Next, the transfer material S on which the toner image is secondarily transferred is conveyed to the fixing nip of the fixing unit 10, and the toner image is fixed onto the transfer material S by the heat and pressure of the fixing nip.

  Untransferred toner on the photosensitive drum 1 that has not been transferred to the intermediate transfer belt 51 at the primary transfer nip N1 is cleaned by a cleaning device 6 disposed downstream of the primary transfer nip N1. Further, the transfer residual toner on the intermediate transfer belt 51 that has not been transferred to the transfer material S at the secondary transfer nip N2 is the first belt cleaning device 8A and the second belt cleaning device disposed downstream of the secondary transfer nip N2. It is cleaned by 8B.

  In the first embodiment, the first belt cleaning device 8A and the second belt cleaning device 8B clean the intermediate transfer belt 51 by electrically attracting and moving toner using an electrostatic fur brush. The first belt cleaning device 8 </ b> A and the second belt cleaning device 8 </ b> B are applied with negative and positive, that is, cleaning voltages having opposite polarities, corresponding to the positive and negative toners attached to the intermediate transfer belt 51.

  The image forming apparatus 100 can also form a black single color image using only the black image forming unit Pd, for example. In this case, the image forming process similar to the above is performed only in the image forming unit Pd, and only the black toner image is formed on the intermediate transfer belt 51. The toner image is transferred to the transfer material S at the secondary transfer nip N2, and then conveyed to the fixing device 10 to be fixed.

[Image density control]
As shown in FIG. 2, yellow (Y), magenta (M), cyan (C), and black (Bk) control images (control toner images, patch images) Ga to Gd are formed on the intermediate transfer belt 51. It is formed. FIG. 2 illustrates control images Ga to Gd formed on the intermediate transfer belt 51, using an example in which the A3 size transfer material S is used for vertical feeding (feeding along the longitudinal direction of the transfer material along the transport direction). Is shown schematically. The image forming apparatus 100 detects the control images Ga to Gd by the image density sensors 11A and 11B over the intermediate transfer belt 51, and controls the toner image density in each of the image forming units Pa to Pd (FIG. 1).

  As shown in FIG. 1, the image density sensor 11 is disposed at a position where the control image can be read on the outer peripheral side of the intermediate transfer belt 51. In the first embodiment, two image density sensors 11 </ b> A and 11 </ b> B are provided in the width direction of the intermediate transfer belt 51 (direction orthogonal to the belt surface movement direction) at a position facing the driving roller 52. Each of the image density sensors 11A and 11B is a light reflection type sensor, and includes a light emitting unit and a light receiving unit. Then, the control images Ga to Gd (FIG. 2) made of toner formed on the intermediate transfer belt 51 are irradiated with light, and the reflected light is measured. Detection signals of the image density sensors 11A and 11B are transmitted to the control unit 110.

  The control unit 110 performs image density control and the like in order to obtain an appropriate image density from the detection signals of the image density sensors 11A and 11B. Image density control includes creation or correction control of conversion characteristics (such as a γ correction table) for converting an input image signal into laser output in accordance with apparatus characteristics, environment, and the like. Examples of the image density control include control of image forming process conditions (development contrast, laser power, etc.) or control of toner density of the developer in the developing device 4 (toner replenishment control). In the first embodiment, the control itself performed using the control images Ga to Gd is arbitrary, and may be used for other control than the above.

  The control images Ga to Gd (FIG. 2) are formed in the image forming units Pa to Pd in the same image forming process as normal image formation, and are formed, developed, and primary electrostatic images (control reference electrostatic images). It is formed on the intermediate transfer belt 51 through each transfer process.

  As shown in FIG. 2, in the first embodiment, from the viewpoint of image stabilization, control images (patch images) Ga to Gd are formed between all sheets in continuous image formation on a plurality of transfer materials S. Yes. Control images Ga and Gb (or Gc and Gd) are formed at two positions in the width direction of the intermediate transfer belt 51 between the sheets in accordance with the arrangement of the image density sensors 11A and 11B. In order not to reduce the productivity of the image forming apparatus 100, the distance between sheets is set to be as narrow as possible, and one control image Ga to Gd is formed between the sheets in the surface movement direction of the intermediate transfer belt 51. The

The width (the direction perpendicular to the surface movement direction of the intermediate transfer belt 51) W of the control images Ga to Gd is 20 mm, and the length (the surface movement direction of the intermediate transfer belt 51) A of the control images Ga to Gd is 10 mm. The control images Ga to Gd are each formed in a region between transfer materials (between sheets), which is a region between toner images transferred to the transfer material S, with a size of width (W) 20 mm × length (A) 10 mm. . The toner density of the control images Ga to Gd is 0.7 mg / cm ² .

  The length of the control images Ga to Gd is preferably in the range of 20 mm to 70 mm. When the length A of the control images Ga to Gd is less than 20 mm, the sensitivity of the image density sensor 11 that reads the control image decreases, and the reading error increases. On the other hand, if the control images Ga to Gd exceed 70 mm, it is necessary to extend the length between sheets, and the productivity (the number of sheets that can be output per minute) of the image forming apparatus 100 decreases.

[Secondary transfer nip]
As shown in FIG. 3, the secondary transfer device 150 includes a backup roller 54, an intermediate transfer belt 51, a secondary transfer roller 56, and a secondary transfer member cleaning device 7. The backup roller 54 rotates in contact with the inner peripheral surface of the intermediate transfer belt 51, and the secondary transfer roller 56 rotates in contact with the outer peripheral surface (toner image carrying surface) of the intermediate transfer belt 51.

  The secondary transfer roller 56 is pressed against the backup roller 54 via the intermediate transfer belt 51 to form a secondary transfer nip N2 between the secondary transfer roller 56 and the intermediate transfer belt 51. In the first embodiment, the secondary transfer roller 56 has a layer configuration of two or more layers including an elastic rubber layer and a coating layer (surface layer). The elastic rubber layer is composed of a carbon black dispersed conductive foam layer having a cell diameter of 0.05 to 1.0 mm. The surface layer is made of a fluororesin-based material having a thickness of 0.1 to 1.0 mm obtained by dispersing an ion conductive polymer. The secondary transfer roller 56 is a rotating body having an outer diameter of 24 mm, and is electrically grounded.

  In consideration of the transportability of the transfer material S, the transportability of the secondary transfer roller 56 decreases when the surface roughness is 1.5 μm or less. Therefore, the surface roughness Rz of the surface layer of the secondary transfer roller 56 is preferably controlled to Rz> 1.5 μm, and more preferably Rz> 6 μm.

  Further, when cleaning the toner adhering to the secondary transfer roller 56, if the surface roughness is 15 μm or more, the cleaning performance is deteriorated. Therefore, the surface roughness Rz of the secondary transfer roller 56 is preferably set to Rz <15 μm, more preferably Rz <12 μm, in consideration of cleaning properties and the like.

  That is, the secondary transfer roller 56 is composed of an elastic member having a coating layer on the surface, and the surface roughness Rz of the surface layer is preferably 1.5 μm ≦ Rz ≦ 15 μm, more preferably 6 μm ≦ Rz ≦. 12 μm. As described above, by using the secondary transfer roller 56 having a coating layer on the surface and having the surface layer uniformly roughened, the transfer of the transfer material S can be stabilized.

The electrical resistance value of the secondary transfer roller 56 is desirably 1.5 × 10 ^{5 to} 1.5 × 10 ⁶ Ω / cm. If the resistance value is lower than 1.5 × 10 ⁵ Ω / cm, charge cannot be supplied to the toner, and transferability is impaired. On the other hand, when the resistance value is higher than 1.5 × 10 ⁶ Ω / cm, there is a problem that the capacity of the high-voltage power supply is insufficient, or the applied voltage is too high, so that leakage tends to occur. Therefore, in this embodiment, the resistance value of the secondary transfer roller 56 is set to 5 × 10 ⁵ Ω / cm.

  The peripheral speed of the secondary transfer roller 56 is substantially equal to the surface moving speed of the intermediate transfer belt 51, and the backup roller 54 rotates at substantially the same peripheral speed as the secondary transfer roller 56. The backup roller 54 is a rotating body having an outer diameter of 24 mm, and preferably rotates at a peripheral speed (surface moving speed) of 200 to 500 mm / second. In the first embodiment, rotation is performed at a peripheral speed of 300 mm / sec.

  A voltage of −3 kV having the same polarity as the normal charging polarity (−) of the toner is applied as a secondary transfer bias from the secondary transfer bias power source 57 to the backup roller 54. In the first embodiment, the secondary transfer roller 56 is grounded and a secondary transfer bias is applied to the backup roller 54. However, even if the backup roller 54 is grounded and a secondary transfer bias of 3 kV having a polarity opposite to the normal charging polarity (−) of the toner is applied to the secondary transfer roller 56, the first implementation is performed in the secondary transfer nip N2. A necessary electric field similar to that of the embodiment can be secured. The same applies when the secondary transfer bias is divided and applied to both the backup roller 54 and the secondary transfer roller 56.

[Secondary transfer member cleaning device]
As shown in FIG. 3, the secondary transfer member cleaning device 7 cleans the secondary transfer roller 56 on the upstream side of the secondary transfer nip N2. The secondary transfer member cleaning device 7 includes a fur brush 71 as a first cleaning member, a metal roller 72 as a second cleaning member, a cleaning blade 73 as a removing unit, and a waste toner container 74. The fur brush 71 electrostatically attracts and collects toner on the secondary transfer roller 54. The metal roller 72 contacts the fur brush 71 to apply a cleaning voltage, and electrostatically attracts and collects toner from the fur brush 71. The cleaning blade 73 is disposed in contact with the metal roller 72, scrapes off the toner on the metal roller 72 and collects it in the waste toner container 74.

  Further, the secondary transfer member cleaning device 7 has a cleaning voltage power source 75 as power source means for outputting a cleaning voltage. The cleaning voltage power supply 75 is connected to the metal roller 72, and the cleaning voltage output from the cleaning voltage power supply 75 is applied to the fur brush 71 via the metal roller 72. In addition, it is preferable to use a member having excellent conductivity such as aluminum or SUS for the metal roller 72.

  In the first embodiment, a grounded conductive (high resistance) secondary transfer roller 56 and a metal roller 72 are electrically connected via a fur brush 71 formed of a conductive material. Accordingly, when a cleaning voltage is applied to the metal roller 72 and a current flows between the secondary transfer roller 56, a potential difference divided by resistance is generated between the fur brush 71 and the metal roller 72. The toner electrostatically adsorbed from the secondary transfer roller 56 to the fur brush 71 is adsorbed by this potential difference and transferred from the fur brush 71 to the metal roller 72 in order. The toner transferred to the metal roller 72 is removed by the cleaning blade 73 in contact with the metal roller 72 and dropped into the waste toner container 74 and collected. This prevents toner from being excessively accumulated on the fur brush 71.

  The fur brush 71 preferably has an outer diameter of 10 mm to 30 mm in a state where it does not enter the secondary transfer roller 56 from the viewpoint of space. In the first embodiment, the outer diameter of the fur brush 71 is 18 mm and the radius is 9 mm in a state where it does not enter the secondary transfer roller 56. Further, the fur brush 71 has a hair length of 4 mm, an intrusion amount with respect to the secondary transfer roller 56 is 1.0 mm, and an intrusion amount with respect to the metal roller 72 is 1.5 mm.

The fur brush 71 has a bristle density of 120 kF / inch ² and the fur brush 71 has an electric resistance of 3 × 10 ⁵ Ω / cm. The circumferential speed of the metal roller 72 is 1.0 (the same speed) in the same direction as the circumferential movement direction of the secondary transfer roller 56 at the contact portion of the secondary transfer roller 56.

The electric resistance value of the fur brush 71 is 3 × 10 ⁴ Ω / cm or more and 3 × 10 in order to secure a potential gradient necessary for the fur brush 71 with the electric resistance value of the secondary transfer roller 56 within the above range. ⁶ Ω / cm or less is desirable.

  The circumferential movement direction of the fur brush 71 is opposite to the circumferential movement direction of the secondary transfer roller 56 at the contact portion with the secondary transfer roller 56. In this case, the range in which the toner collection efficiency is high is 0.15V0 ≦ V1 when the peripheral surface moving speed of the secondary transfer roller 56 by the fur brush 71 is V0 and the peripheral surface moving speed of the fur brush 71 is V1. Experiments have confirmed that ≦ 1.0V0.

  The circumferential movement direction of the metal roller 72 is the same as the circumferential movement direction of the fur brush 71 at the contact portion with the fur brush 71. In this case, the range in which the cleaning efficiency of the fur brush 71 is high is 0.8V1 ≦ V2 ≦ 3.0V1 when the peripheral surface moving speed of the fur brush 71 is V1 and the peripheral surface moving speed of the metal roller 72 is V2. It has been confirmed by experiments.

[Cleaning efficiency of cleaning process 1 and cleaning process 2]
4 is an explanatory diagram of the cleaning process of the secondary transfer roller, FIG. 5 is a diagram of the cleaning efficiency in the cleaning steps 1 and 2, and FIG. 6 is a time chart of the cleaning applied voltage.

  As shown in FIG. 4, the process in which the secondary transfer member cleaning device 7 cleans the toner of the control image G attached to the secondary transfer roller 56 includes two consecutive steps. The first process is a cleaning process 1 in which a first cleaning voltage of 180 V is applied to attract and move toner from the secondary transfer roller 56 to the fur brush 71. The second step is a cleaning step 2 in which a second cleaning voltage of 280 V is applied to attract and move toner from the fur brush 71 to the metal roller 72. Since the control image G has a remarkably high toner concentration compared to normal adhesion dirt, a good cleaning result cannot be obtained unless a large amount of toner is attracted and moved in each of the cleaning steps 1 and 2.

  Here, in order to quantify the cleaning characteristics of the control image G through the cleaning steps 1 and 2, the cleaning efficiency in each step was measured. The measurement of the cleaning efficiency in the cleaning process 1 was calculated from the densities a and b of the control image G before and after the control image G passed the cleaning process 1. Specifically, the image forming apparatus 100 is stopped before and after the control image G passes the cleaning step 1, and the density of the sample piece obtained by transferring the control image G to the transparent seal is set to a spectral densitometer 500 manufactured by X-RITE. Measured using series. This is because it is difficult to transfer the control image attracted to the fur brush 71 to the transparent seal.

When the control image G has the density b after passing the density a before passing the cleaning process 1, the cleaning efficiency α (%) in the cleaning process 1 is
α = ((a−b) / a) × 100 (%)
It is.

Next, the control image G transferred onto the metal roller 72 was transferred to a transparent seal, and the density c was measured in the same manner. Since (ab) corresponds to the amount of toner adsorbed to the fur brush 71, the cleaning efficiency β (%) in the cleaning step 2 is the ratio of the amount of toner moving from the fur brush 71 to the metal roller 72. Is
β = (c / (ab)) × 100 (%)
It is.

  FIG. 5 shows the experimental results obtained by measuring the cleaning efficiencies α and β while changing the output value of the cleaning voltage. The cleaning voltage power source 75 in this experiment is a constant voltage control system in which the voltage is always kept constant. The horizontal axis of the graph indicates the cleaning voltage output voltage, and the vertical axis indicates the cleaning efficiency. It means that the higher the cleaning efficiency is, the better the cleaning property is, and the threshold when the cleaning failure occurs is 90% of the cleaning efficiency. That is, if the cleaning efficiency α, β is less than 90% in any of the cleaning steps 1 and 2, a cleaning defect that appears sooner or later as the back contamination of the transfer material S occurs. Therefore, in order to avoid a cleaning failure, it is necessary to set the cleaning efficiency α and β to a cleaning voltage at which the cleaning efficiency α and β are 90% or more in both the cleaning steps 1 and 2.

  However, as shown in FIG. 5, the cleaning efficiency α and β are both equal to or more than 90% when the cleaning voltage is limited to a very narrow range centered at 220 (V).

  Further, the cleaning voltage at which the cleaning efficiency α, β is maximized is shifted to about 180 V in the cleaning process 1 and about 280 V in the cleaning process 2. For this reason, the range in which both of the cleaning efficiencies α and β are equal to or greater than 90% is shifted from the range in which the cleaning steps 1 and 2 individually have the best cleaning performance.

  Therefore, in the first embodiment, as shown in FIG. 1, the control unit 110 controls the cleaning voltage power supply 75 to switch the cleaning voltage as shown in FIG. A cleaning voltage of 180 V at which the cleaning efficiency α is maximized and a cleaning voltage of 280 V at which the cleaning efficiency β is maximized were alternately used. 180 V was applied during the cleaning process 1 for cleaning the control image G, and 280 V was applied during the cleaning process 2 for cleaning the fur brush 71 for 0.2 seconds each. Other than that, 220 V was applied so that both the cleaning efficiencies α and β were 90% or more.

  Table 1 shows the back dirt level at that time. Durability tests are performed to evaluate the cleaning performance when (1) the cleaning voltage is made constant and (2) when the cleaning voltage is changed to the optimum voltage value of the cleaning voltage. As shown in Table 1, stable and good cleaning characteristics could be maintained by changing the cleaning voltage in accordance with the cleaning process, rather than making the cleaning voltage constant. It was possible to prevent the back of the paper from being stained for the durability of 200,000 sheets from the beginning.

  By the way, as shown in FIG. 5, in the region where the cleaning voltage is too low, the cleaning efficiency α and β are low in both the cleaning steps 1 and 2. This is presumably because the current (= charge amount) for transferring the toner to the fur brush 71 or the metal roller 72 is insufficient compared to the charge amount of the toner.

  On the other hand, in the region where the cleaning voltage is too high, since the current value (charge amount) is too much compared to the charge amount possessed by the toner, there is a high possibility that the toner charge will be reversed and become the reverse polarity (+). . As a result, it is considered that the cleaning efficiency is lowered due to escape from adsorption to the fur brush 71 and the metal roller 72 to which a positive cleaning voltage is applied.

  Further, it is considered that the reason why the optimum voltage value for the cleaning operation differs between the cleaning process 1 and the cleaning process 2 is the difference in the shapes of the fur brush 71 and the metal roller 72. The fur brush 71 is a brush using a hair material having a fiber diameter of 10 to 30 μm and a length of 4 to 6 mm, and thus has a very large surface area for adsorbing toner. Therefore, the toner adsorbing property (cleaning step 1) is good due to the diffusion process from the secondary transfer roller having an increased adhesion area to the fur brush. However, the toner movement from the fur brush to the metal roller is a concentration process in which the adsorption area is reduced, so that the toner adsorption property (cleaning property) in the cleaning step 2 is lower than that in the cleaning step 1. In order to achieve the same level as in the cleaning step 1, it is necessary to increase the voltage.

  Therefore, it is desirable to apply the cleaning voltage 180V at the timing when the control image G attached to the secondary transfer roller 56 passes through the fur brush 71. Temporary accumulation of toner on the fur brush 71 is allowed, and the maximum transfer from the secondary transfer roller 56 to the fur brush 71 is realized, so that the secondary transfer roller 56 is preferentially cleaned.

  At a timing when the control image G does not pass through the fur brush 71, it is desirable to apply the cleaning voltage 280V. Ignoring the charge reversal of a small amount of toner adhering to the secondary transfer roller 56, the maximum efficiency movement from the fur brush 71 to the metal roller 72 is realized. As a result, the fur brush 71 is preferentially cleaned, and the temporarily accumulated toner is quickly removed.

  The timing of the applied voltage in the time chart shown in FIG. 6 is set in such a way that the control unit 110 recognizes the control image G on the intermediate transfer belt 51 and is incorporated in a sequence for performing secondary transfer onto the transfer material S. Yes.

Second Embodiment
7 is an explanatory diagram of the configuration around the secondary transfer unit in the second embodiment, FIG. 8 is an explanatory diagram of the cleaning process of the secondary transfer roller, FIG. 9 is a diagram of the cleaning efficiency in the cleaning steps 1 and 2, and FIG. Is a time chart of the cleaning applied voltage. The secondary transfer member cleaning device 7B in the second embodiment is arranged by replacing the secondary transfer member cleaning device 7 of the image forming apparatus 100 shown in FIG. The secondary transfer member cleaning device 7B is configured similarly to the secondary transfer member cleaning device 7 except that there are two fur brushes 71a and 71b. Therefore, description will be made with reference to FIGS. 1 and 2 in common, and in FIGS. 7 and 8, components common to FIGS. 3 and 4 are denoted by common reference numerals and detailed description thereof will be omitted.

As shown in FIG. 7, in the second embodiment, in order to further increase the stability and durability in cleaning of the secondary transfer roller 56, the two fur brushes 71a and 71b are brought into contact with the secondary transfer roller 56 and moved. Arranged. The two fur brushes 71a and 71b are commonly applied with a cleaning voltage via the metal roller 72, and have the same electric resistance value of 3 × 10 ⁶ Ω / cm. Further, the peripheral speeds of the fur brushes 71a and 71b are the same, and the peripheral speed ratio is set to 0.5 in the direction opposite to the peripheral surface moving direction of the secondary transfer roller 56 at the contact portion with the secondary transfer roller 56. The cleaning efficiencies α and β at this time were measured by the same method as in the first embodiment.

  As shown in FIG. 8, a process in which the control image G is transferred from the secondary transfer roller 56 to the fur brush 71a is defined as a cleaning process 1A, and a process in which the control image G is transferred to the fur brush 71b is defined as a cleaning process 1B. Further, a process of transferring from the control image G fur brush 71a to the metal roller 72 is defined as a cleaning process 2A, and a process of transferring from the fur brush 71b to the metal roller 72 is defined as a cleaning process 2B.

  The density of the control image G on the secondary transfer roller 56 before cleaning is a, the density of the control image G after the cleaning process 1A is b, and the density of the control image G after the cleaning process 1B is c. Further, the density of the control image G transferred onto the metal roller 72 in the cleaning process 2A is d, and the density of the control image G transferred onto the metal roller 72 in the cleaning process 2B is e. The densities a, b, c, d, and e of the control image G were transferred to a transparent seal and measured with a spectral densitometer as in the first embodiment.

At this time, the cleaning efficiencies αA and αB in the cleaning steps 1A and 1B are:
αA = ((ab) / a) × 100 (%)
αB = ((bc) / b) × 100 (%)
The overall cleaning efficiency α through the cleaning steps 1A and 1B is
α = ((ac) / a) × 100 (%)
It is.

Further, the cleaning efficiency in the cleaning steps 2A and 2B, βA and βB are:
βA = (d / (ab)) × 100 (%)
βB = (e / (bc)) × 100 (%)
The overall cleaning efficiency β through the cleaning steps 2A and 2B is
β = (d + e) / (ac)
It is.

  FIG. 9 shows the overall cleaning efficiencies α and β in the cleaning steps 1A, 1B, 2A, and 2B obtained in this way in comparison with the cleaning efficiencies of the cleaning steps 1 and 2 in the first embodiment. In the second embodiment, it has been found that the number of fur brushes increased from one to two, so that the peak of the cleaning efficiency is shifted to the lower electric voltage side than in the first embodiment. This is considered to be because when the cleaning voltage is lowered, even if the cleaning efficiency of the fur brush 71a alone is lowered, the charging inversion is reduced and the cleaning efficiency of the fur brush 71b alone is increased.

  In the second embodiment, the peak value of the cleaning efficiency is higher than that in the first embodiment. This is because the cleaning voltage is low, and the cleaning efficiency of the fur brushes 71a and 71b alone is lower than that of the first embodiment, but the number of cleanings is one while the control image transferred onto the secondary transfer roller 56 makes one round. It is thought that it doubles to 2 times.

  In the second embodiment, the cleaning efficiencies α and β are simultaneously high when the cleaning voltage is 60V. The cleaning voltage at which the cleaning efficiency α forms a peak is about 30 V, and the cleaning voltage at which the cleaning efficiency β forms a peak is about 80 V.

  Therefore, in the second embodiment, as shown in FIG. 10, the cleaning voltage 30V at which the cleaning efficiency α is maximized and the cleaning voltage 80V at which the cleaning efficiency β is maximized are alternately used. 30 V was applied during the cleaning steps 1A and 1B when the control image G passes through the fur brushes 71a and 71b, and 80 V was applied during the cleaning steps 2A and 2B performed at intervals of the control image G for 0.3 seconds. Other than that, a high 60 V was applied with both the cleaning efficiencies α and β.

  Table 2 shows the level of back dirt at that time. Even when the voltage is applied at a constant voltage of 60 V, the number of images that can be formed until the back stain is generated can be increased as compared with the case where the voltage is varied in the single fur brush system of the first embodiment. Further, when the voltage was varied in the two-fur brush system of the second embodiment, no back contamination occurred even when 350,000 sheets were passed, and good cleaning characteristics could be maintained.

  According to the second embodiment, the high-density toner of the control image G transferred to the secondary transfer roller 56 is removed better than in the first embodiment, and the back side of the transfer material S, the image during double-sided printing, are removed. Defects can be prevented for a long time. Further, in accordance with the control images between the sheets formed during image formation on various transfer materials S, it is possible to always achieve good cleaning performance of the secondary transfer roller 56 by the fur brushes 71a and 71b. Accordingly, it is possible to improve the cleaning performance of the secondary transfer member when the control image is repeatedly formed at a predetermined interval in the plurality of transfer material areas as compared with the first embodiment.

<Background of development>
In recent years, for example, in an image forming apparatus that forms a toner image by an electrophotographic image forming process, there is a demand for a technology that supports high image quality close to photographic quality and high speed close to a printing press. In a tandem image forming apparatus that supports high speed, a control image is formed on a non-image portion of the intermediate transfer belt to detect reflection density and the like in order to achieve high image quality without impairing the high speed. ing. The detection result is fed back to the image forming process conditions and the like, so that the color stability and density uniformity are stably maintained.

  The control image is formed in a region between the transfer material and the transfer material during non-image formation, for example, during continuous image formation for a plurality of transfer materials. For this reason, a cleaning device is provided to remove the control image so that the control image does not adhere to an image formed product by normal image formation.

  In the case of the photosensitive drum and the intermediate transfer belt, the transfer image can be passed with the polarity of the transfer bias in the primary transfer nip and the secondary transfer nip reversed, and can be removed by a dedicated cleaning device for each image carrier.

  However, in the recent trend toward higher speeds, it is difficult to reverse the polarity of the transfer bias for each control image between papers in terms of time and distance between papers. When the polarity of the transfer bias cannot be reversed, the control image is transferred from the photosensitive drum onto the intermediate transfer belt, and transferred from the intermediate transfer belt to the secondary transfer roller.

  When transfer of the control image to the secondary transfer roller is allowed, it is expected that the back of the transfer material will be stained. Therefore, it has been proposed to install a dedicated cleaning device on the secondary transfer roller. As a cleaning device, a blade system having a simple structure and high cleaning ability is generally used. Further, the secondary transfer roller itself is also provided with a fluorine coating or the like on the surface layer to stabilize the running performance of the blade, thereby improving the cleaning performance by the blade method.

  However, from the viewpoint of transportability of the transfer material, it is difficult to completely clean a high-density control image when a secondary transfer roller having a rough surface layer is used. It is necessary to increase the linear pressure at the nip portion between the secondary transfer roller and the blade by increasing the contact pressure of the blade or increasing the contact angle. However, since both the secondary transfer roller and the cleaning blade are elastically deformed to increase friction, when the linear pressure is increased, toner adheres and the cleaning blade is likely to bend.

  In view of this, it has been proposed to use electrostatic fur brush cleaning in order to clean the secondary transfer roller having a rough surface layer, in which the surface shape of the member to be cleaned is less restricted than in the blade method.

  However, when a secondary transfer member cleaning device using an electrostatic fur brush was examined, it was found that there was a problem in durability of the fur brush, cleaning stability, etc. when the voltage applied to the metal roller was constant. did. As described above, the cleaning process 1 and the cleaning process 2 have different optimum voltage values for the cleaning operation that electrostatically attracts toner.

  In addition, for the purpose of image stabilization, the frequency of forming a control image typified by one for density control may be increased by forming it between each sheet. Furthermore, in order to improve the reading accuracy with the sensor, a control image having as large an area as possible may be formed. In such a case, in the electrostatic fur brush cleaning, it is difficult to frequently clean the high density toner, and the toner may be clogged in the fur brush hair. As a result, the function as a fur brush cannot be exhibited sufficiently, which may cause a cleaning defect that causes backside contamination of the transfer material or image defects during double-sided printing.

  On the other hand, in the first and second embodiments described above, such a problem can be solved by optimizing the cleaning voltage applied to the electrostatic fur brush.

<Correspondence with Invention>
The secondary transfer member cleaning device 7 of the first embodiment has conductivity, a fur brush 71 that circulates in contact with the toner adhesion surface, and conductivity, and the fur brush 71 contacts the adhesion surface. A metal roller 72 that contacts the fur brush 71 at a circulating position that does not, a cleaning blade 73 that removes toner adhered to the metal roller 72 via the fur brush 71, and a voltage applied to the metal roller 72 to apply the fur brush. And a cleaning voltage power source 75 for charging 71. The cleaning voltage power source 75 can apply a second cleaning voltage to the metal roller 72 that is different from the first cleaning voltage when removing toner from the attached surface. The second cleaning voltage is set to a voltage value that prioritizes the movement of toner from the fur brush 71 to the metal roller 72 over the movement of toner from the adhesion surface to the fur brush 71.

  In the secondary transfer member cleaning device 7, the second cleaning voltage is applied in a time-sharing manner in the image forming cycle, and the movement of the toner from the fur brush 71 to the metal roller 72 is made efficient. That is, at the timing when the necessity of removing the toner from the adhesion surface is low, the maximum efficiency for removing the toner from the fur brush 71 can be exhibited by the second cleaning voltage ignoring the cleaning effect on the adhesion surface.

  In other words, if there is no toner to be removed on the adhesion surface, the toner accumulated in the fur brush 71 can be positively removed using the second cleaning voltage (280 V). Thereby, at the timing when there is toner to be removed on the next adhering surface, it is possible to perform efficient cleaning with less toner reverse transfer to the adhering surface using the fur brush 71 with less toner accumulation.

  Therefore, the cleaning efficiency of the adhesion surface can be maintained high over a long period of time while repeating the image forming cycle in which the toner to be removed adheres to the adhesion surface intermittently. The toner can be efficiently moved from the fur brush 71 to the metal roller 72 without impairing the ability of the fur brush 71 to remove the toner from the surface of the secondary transfer roller 56.

  In the secondary transfer member cleaning device 7, the first cleaning voltage (180 V) is a voltage value in which the toner movement from the adhesion surface to the fur brush 71 is prioritized over the toner movement from the fur brush 71 to the metal roller 72. Is set to

  The cleaning voltage power supply 75 in the secondary transfer member cleaning device 7 applies the first cleaning voltage when there is toner to be removed on the adhesion surface, and the second cleaning voltage when there is no toner to be removed on the adhesion surface. Apply to the metal roller 72.

  The secondary transfer member cleaning device 7B of the second embodiment arranges the plurality of fur brushes 71a and 71b in contact with a common metal roller 72. The cleaning voltage power supply 75 applies a first cleaning voltage (30 V) and a second cleaning voltage (80 V) to the metal roller 72 that are lower than those in the case of the first embodiment with one fur brush 71.

  The fur brush 71 in the secondary transfer member cleaning device 7 of the first embodiment is a roll-shaped fur brush in which a flexible bristle material made of a conductive material is planted in a cylindrical shape. The metal roller 72 is a metal roller that is rotationally driven. The second cleaning voltage (280V) is set higher than the first cleaning voltage (180V).

  The image forming apparatus 100 forms a secondary transfer nip N2 between the intermediate transfer belt 51 carrying the image toner image and the intermediate transfer belt 51, and transfers the image toner image onto the transfer material S. And a roller 56. The secondary transfer member cleaning device 7 is disposed in contact with the fur brush 71 on at least one of the intermediate transfer belt 51 and the secondary transfer roller 56.

  The image forming apparatus 100 forms a secondary transfer nip N2 between the intermediate transfer belt 51 carrying the image toner image and the intermediate transfer belt 51, and transfers the image toner image onto the transfer material S. The control image G is carried at the interval between the roller 56, the image density sensors 11A and 11B for optically detecting the control image G carried on the intermediate transfer belt 51, and the image toner image carried on the intermediate transfer belt 51. And a control unit 110 that is detected by the image density sensors 11A and 11B. The secondary transfer member cleaning device 7 is disposed by bringing the fur brush 71 into contact with the secondary transfer roller 56. The control unit 110 controls the cleaning voltage power source 75 to output the first cleaning voltage and the second cleaning voltage corresponding to the moving position of the control image G carried on the intermediate transfer belt 51.

  The image forming apparatus 110 employs the transfer member cleaning device 7 as described above, so that the back side of the transfer material S through the secondary transfer roller 56 can be obtained even when the control image G is frequently formed on the intermediate transfer belt 51. Dirt can be prevented over a long period of time. While the control image G adhering to the secondary transfer roller 56 from the intermediate transfer belt 51 is efficiently removed by the fur brush 71, the toner accumulation of the fur brush 71 can be suppressed and the back contamination of the transfer material S can be prevented for a long period of time.

It is explanatory drawing of schematic structure of the image forming apparatus of 1st Embodiment. It is explanatory drawing of arrangement | positioning of a control image. It is explanatory drawing of a structure around a secondary transfer part. It is explanatory drawing of the cleaning process of a secondary transfer roller. It is a diagram of the cleaning efficiency in the cleaning steps 1 and 2. It is a time chart of cleaning applied voltage. It is explanatory drawing of the structure of the secondary transfer part periphery in 2nd Embodiment. It is explanatory drawing of the cleaning process of a secondary transfer roller. It is a diagram of the cleaning efficiency in the cleaning steps 1 and 2. It is a time chart of cleaning applied voltage.

Explanation of symbols

N2 Secondary transfer nip S Transfer material 1 Photosensitive drum 2 Charging roller 3 Exposure device 4 Developer 5 Intermediate transfer unit 6 Cleaning device 7 Cleaning device (secondary transfer member cleaning device)
8A, 8B Belt cleaning devices 11A, 11B Image density sensor 51 Image carrier (intermediate transfer belt)
54 Backup roller 55 Primary transfer roller 56 Transfer member (secondary transfer roller)
71, 71a, 71b First cleaning member (fur brush)
72 Second cleaning member (metal roller)
73 Removal means (cleaning blade)
74 Waste toner container 75 Power supply means (cleaning voltage power supply)
DESCRIPTION OF SYMBOLS 100 Image forming apparatus 100A Apparatus main body 110 Control means (control part)

Claims (11)

A first cleaning member having conductivity and circulating in contact with the toner adhesion surface;
A second cleaning member having electrical conductivity and contacting the first cleaning member at a circulating position where the first cleaning member does not contact the adhesion surface;
Removing means for removing toner attached to the second cleaning member via the first cleaning member;
A power supply means for applying a voltage to the second cleaning member to charge the first cleaning member,
The power supply means can apply a second cleaning voltage to the second cleaning member, which is different from a first cleaning voltage for removing toner from the adhesion surface;
The second cleaning voltage is set to a voltage value that prioritizes the movement of toner from the first cleaning member to the second cleaning member over the movement of toner from the attachment surface to the first cleaning member. A cleaning device.   The first cleaning voltage is set to a voltage value that prioritizes the movement of toner from the adhesion surface to the first cleaning member over the movement of toner from the first cleaning member to the second cleaning member. The cleaning device according to claim 1.   The power supply means applies a first cleaning voltage to the second cleaning member when there is toner to be removed on the adhesion surface and a second cleaning voltage when there is no toner to be removed on the adhesion surface. The cleaning device according to claim 2. A plurality of the first cleaning members are disposed in contact with the common second cleaning member;
4. The cleaning apparatus according to claim 3, wherein the power supply means applies the first cleaning voltage and the second cleaning voltage that are lower than the case where the number of the first cleaning members is one to the second cleaning member. . The first cleaning member is a roll-shaped fur brush in which a flexible bristle material made of a conductive material is planted in a cylindrical shape,
The second cleaning member is a rotationally driven metal roller,
The cleaning device according to claim 3, wherein the second cleaning voltage is set higher than the first cleaning voltage. An image carrier for carrying an image toner image;
An image forming apparatus comprising: a transfer member that forms a transfer nip with the image carrier and transfers the image toner image to a transfer target;
6. The image forming apparatus according to claim 1, wherein the first cleaning member is brought into contact with at least one of the image carrier and the transfer member. An image carrier for carrying an image toner image;
A transfer member that forms a transfer nip with the image carrier to transfer the image toner image onto a transfer material;
Detection means for optically detecting a control toner image carried on the image carrier;
An image forming apparatus comprising: a control unit configured to carry the control toner image at intervals between the image toner images carried on the image carrier and to detect the control toner image.
The cleaning device according to claim 3, wherein the first cleaning member is brought into contact with the transfer member.
The control means controls the power supply means to output the first cleaning voltage and the second cleaning voltage in correspondence with the moving position of the control toner image carried on the image carrier. An image forming apparatus. The image carrier is an intermediate transfer belt that circulates in contact with a plurality of photosensitive drums arranged in series,
The transfer member is a secondary transfer roller that forms the transfer nip with respect to a transfer material,
The secondary transfer roller is an elastic member having a coating layer on the surface, and when the surface roughness of the surface layer is Rz, 1.5 μm ≦ Rz ≦ 15 μm,
8. The image forming apparatus according to claim 7, wherein when the electric resistance value of the secondary transfer roller is r0, 1.5 × 10 ⁵ ≦ r0 ≦ 1.5 × 10 ⁶ (Ω / cm). . 9. The image forming apparatus according to claim 8, wherein when the electric resistance value of the roll fur brush is r1, 3 × 10 ⁴ ≦ r1 ≦ 3 × 10 ⁶ (Ω / cm). The circumferential movement direction of the roll fur brush is opposite to the circumferential movement direction of the secondary transfer roller at the contact portion with the secondary transfer roller,
10. The velocity of the secondary transfer roller is 0.15V0 ≦ V1 ≦ 1.0V0, where V0 is a peripheral surface moving speed and the first cleaning member is a peripheral surface moving speed V1. Image forming apparatus. The circumferential movement direction of the metal roller is the same direction as the circumferential movement direction of the roll fur brush at the contact portion with the roll fur brush,
11 or 10, wherein V1 is 0.8V1 ≦ V2 ≦ 3.0V1, where V1 is a peripheral surface moving speed of the roll fur brush and V2 is a peripheral surface moving speed of the metal roller. Image forming apparatus.

Images