JP2008292555A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus for preventing the back surface of an intermediate transfer body from being damaged, improving toner image transfer performance from an image carrier to the intermediate transfer body and improving-quality in image formation. <P>SOLUTION: The image forming apparatus 1 is equipped with an intermediate transfer belt 8 temporarily carrying a toner image, and wound around a plurality of rollers composed of a driving roller 8a transmitting rotational force and driven rollers 8b to 8d rotated by rotation of the intermediate transfer belt 8. Insulating treatment is applied to the surfaces of the driven rollers 8b to 8d. Thus, the driven rollers 8b to 8d are easily charged, and electrostatic force acts between the intermediate transfer belt 8 and the driven rollers 8b to 8d, whereby the driven rollers 8b to 8d are attracted to the back surface of the intermediate transfer belt 8. Therefore, a slip between the intermediate transfer belt 8 and the driven rollers 8b to 8d is prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus typified by a copying machine or a printer, and more particularly to an image forming apparatus that transfers a toner image onto a sheet using an intermediate transfer member.

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

  The image forming apparatus includes a type in which a toner image is directly transferred from a photosensitive drum, which is an image carrier, onto a sheet, and a toner image is once carried on an intermediate transfer body and then transferred from the intermediate transfer body to a sheet. There is also. The intermediate transfer member is often found in an image forming apparatus for color printing such as a so-called tandem type image forming apparatus in which image forming units corresponding to a plurality of colors of toner are arranged in a line. An example of such an image forming apparatus can be seen in Patent Document 1.

  In order to maintain a suitable transfer performance for the toner image with respect to the intermediate transfer member, it is necessary to prevent scratches even on the back surface. Scratches on the back surface of the intermediate transfer member, that is, unevenness on the back surface, may cause poor adhesion during transfer of the toner image, and may cause streak image defects. One of the causes of such scratches on the back surface of the intermediate transfer member is adhesion of foreign matters such as toner to the surface of the driven roller among the support rollers around which the intermediate transfer member is wound.

Therefore, in order to solve the above problems, in the image forming apparatus described in Patent Document 1, the surface friction coefficient of the driven roller that stretches and supports the intermediate transfer belt, which is an intermediate transfer member, is determined by the back surface of the intermediate transfer belt. By making it smaller than the friction coefficient, or less than 0.25, foreign matter such as toner adhering to the back surface of the intermediate transfer belt is prevented from moving to the surface of the driven roller and sticking.
Japanese Patent Laying-Open No. 2004-117462 (page 4-5, FIG. 4)

  The image forming apparatus described in Patent Document 1 is considered to be less likely to damage the back surface of the intermediate transfer member because foreign matter such as toner is less likely to adhere to the surface of the driven roller that supports the intermediate transfer member. However, the main cause of the occurrence of scratches on the back surface of the intermediate transfer member is a slip between the intermediate transfer member and the driven roller. In particular, if the slip between the intermediate transfer member and the driven roller, which is likely to occur at the start and stop of the rotation of the intermediate transfer member, can be prevented, the scratches on the back surface of the intermediate transfer member that cause streaky image defects can be greatly reduced. It is possible to make it.

  In order to prevent a slip between the intermediate transfer member and the driven roller, it is conceivable to wrap rubber around the surface of the driven roller. However, some rollers continue to check the rotational speed during operation, and the rubber-wrapped roller thermally expands, so the rotational speed may change depending on the temperature state. As a result, the rotational speed of the intermediate transfer member is adversely affected, the toner image transfer becomes abnormal, and the possibility of image defects increases. In addition, winding rubber around the driven roller leads to an increase in cost.

  The present invention has been made in view of the above points. In an image forming apparatus provided with an intermediate transfer member that once supports a toner image, it is possible to suppress the occurrence of scratches on the back surface of the intermediate transfer member. An object of the present invention is to provide an image forming apparatus capable of improving the performance of transferring a toner image to an intermediate transfer member and capable of performing high-quality image formation.

  In order to solve the above-described problems, the present invention provides an intermediate transfer member that temporarily holds a toner image, a plurality of support rollers around which the intermediate transfer member is wound, a driving roller that transmits a rotational force, In the image forming apparatus provided with at least one driven roller that rotates in accordance with the rotation of the transfer body, at least one of the driven rollers is subjected to insulation treatment on the surface.

  Further, in the image forming apparatus having the above configuration, the insulating process is an alumite process.

  In the image forming apparatus having the above-described configuration, the insulating layer formed by the alumite treatment has a thickness of 20 μm or less.

  According to the configuration of the present invention, the intermediate transfer member that temporarily holds the toner image, the plurality of support rollers around which the intermediate transfer member is wound, the driving roller that transmits the rotational force, and the rotation of the intermediate transfer member In the image forming apparatus provided with at least one driven roller that rotates according to the above, the surface of at least one of the driven rollers is insulated, so that the driven roller is easily charged. As a result, an electrostatic force acts between the intermediate transfer member and the driven roller, and the driven roller is attracted to the back surface of the intermediate transfer member. Therefore, it is possible to prevent slipping between the intermediate transfer member and the driven roller while suppressing an increase in cost without being adversely affected by heat. As a result, it is possible to suppress the occurrence of scratches on the back surface of the intermediate transfer member, improve the toner image transfer performance from the image carrier to the intermediate transfer member, and achieve high-quality image formation. An image forming apparatus can be obtained.

  In addition, since the insulating treatment is an alumite treatment, the surface of the driven roller can be hardened in addition to easy insulation treatment. As a result, it is possible to prevent slippage between the intermediate transfer member and the driven roller by the action of electrostatic force, and to increase the hardness of the surface of the driven roller, thereby suppressing the occurrence of scratches on the back surface of the intermediate transfer member. Can be further increased.

  Further, since the insulating layer formed by the alumite treatment has a thickness of 20 μm or less, it is possible to suppress an increase in electrical resistance of the driven roller. This suppresses an increase in the volume resistivity of the intermediate transfer member even after a very large amount of printing is performed with respect to the driven roller disposed facing the cleaning device for the intermediate transfer member. It is possible to prevent deterioration of the intermediate transfer member. Even if a bias current is applied during cleaning, it is possible to normally clean the toner remaining on the surface of the intermediate transfer member. Therefore, it is possible to prevent slippage between the intermediate transfer member and the driven roller by applying insulation treatment to the surface of the driven roller while preventing the deterioration of the intermediate transfer member and the cleaning performance of the intermediate transfer member.

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

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

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

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

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

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

  On the other hand, the image forming apparatus 1 receives document image data from an external computer (not shown). The information of the image data is sent to a laser irradiation unit 7 that is an exposure unit disposed above the second paper transport unit 6. The laser irradiation unit 7 irradiates the image forming unit 20 with laser light L controlled based on the image data.

  A total of four image forming units 20 are provided above the laser irradiation unit 7, and an intermediate transfer belt 8 using an intermediate transfer member in the form of an endless belt is provided above each image forming unit 20. The intermediate transfer belt 8 is wound around and supported by a plurality of rollers, and is rotated clockwise in FIG. 1 by a driving device (not shown).

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

  In each image forming unit 20, an electrostatic latent image of a document image is formed by the laser light L irradiated by the laser irradiation unit 7 serving as an exposure unit, and the toner image is developed from the electrostatic latent image. The toner image is primarily transferred onto the surface of the intermediate transfer belt 8 by a primary transfer unit 30 provided above each image forming unit 20. As the intermediate transfer belt 8 rotates, the toner image of each image forming unit 20 is transferred to the intermediate transfer belt 8 at a predetermined timing. A color toner image is formed by superimposing the color toner images.

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

  After the secondary transfer, deposits such as toner remaining on the surface of the intermediate transfer belt 8 are cleaned for the intermediate transfer belt 8 provided upstream of the intermediate transfer belt 8 in the rotation direction of the magenta image forming unit 20M. It is cleaned and collected by the device 9.

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

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

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

  Next, a detailed configuration around the intermediate transfer belt 8 of the image forming apparatus 1 will be described with reference to FIG. 2 in addition to FIG. FIG. 2 is a partially enlarged vertical sectional view around the intermediate transfer belt of the image forming apparatus shown in FIG. Since the four color image forming units 20 and the primary transfer unit 30 have the same structure, the identification symbols “M”, “C”, “Y”, and “B” are omitted as described above.

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

  A primary transfer roller 31, which is a primary transfer member, is disposed in the primary transfer unit 30 so as to face the photosensitive drum 21 with the intermediate transfer belt 8 interposed therebetween. The primary transfer roller 31 is in contact with the photosensitive drum 21 via the intermediate transfer belt 8. The primary transfer roller 31 is a roller having a diameter of 20 mm, in which an EPDM (ethylene propylene diene rubber) foam having a thickness of 6 mm is provided on a metal shaft having a diameter of 8 mm. The primary transfer roller 31 does not have a driving device, and rotates according to the rotation of the intermediate transfer belt 8 by contacting the intermediate transfer belt 8. The primary transfer roller 31 is applied with a primary transfer bias of minus 15 μA, which has a polarity different from the charging polarity of the photosensitive drum 21 and the toner, as necessary.

  As shown in FIG. 2, the intermediate transfer belt 8 is wound around and supported by a plurality of rollers. The intermediate transfer belt 8 is an elastic endless belt provided by laminating an elastic layer on the surface of a substrate, and has a volume resistivity of 5.0E + 10 [Ω · cm] and a surface resistivity of 1.0E + 11 [Ω / □]. It is. A PVDF (polyvinylidene fluoride) resin having a thickness of 100 μm is used as a base material of the intermediate transfer belt 8, and a 150 μm conductive CR rubber (chloroprene rubber) is provided as an elastic layer on the surface thereof. Further, the elastic layer is coated with PTFE (polytetrafluoroethylene) having a thickness of 10 μm, and the total thickness of the intermediate transfer belt 8 is 260 μm.

  Among the rollers that support the intermediate transfer belt 8, as shown in FIG. 2, a roller provided at a location facing the secondary transfer roller 41 across the intermediate transfer belt 8 is driven in the vicinity of the secondary transfer portion 40. This is a roller 8a. The drive roller 8a is connected to a stepping motor (not shown) that is a drive motor, and rotates the intermediate transfer belt 8 at a speed of 150 mm / s. The driving roller 8a is a roller having a diameter of 29.4 mm and a metal shaft having a diameter of 27 mm provided with EPDM (ethylene propylene diene rubber) with a thickness of 1.2 mm. The electric resistance value is 1.0E + 5 [Ω]. Hereinafter (when 10 V is applied).

  One secondary transfer roller 41 is a roller having a diameter of 24 mm in which a metal shaft having a diameter of 10 mm is provided with an EPDM (ethylene propylene diene rubber) foam having a thickness of 7 mm. The secondary transfer roller 41 is rotated by obtaining power through a gear from a drive motor connected to a drive roller 8 a that rotates the intermediate transfer belt 8. The secondary transfer roller 41 is applied with a secondary transfer bias of −30 μA, which has a polarity different from that of the photosensitive drum 21 or the toner, as necessary.

  The other three rollers 8 b to 8 d that support the intermediate transfer belt 8 are driven rollers that rotate according to the rotation of the intermediate transfer belt 8. These driven rollers 8b to 8d are made of aluminum, and the surface thereof is insulated. This insulation treatment is an alumite treatment, and the thickness of the insulation layer is 8 μm. The driven roller 8 c serves as a counter roller of the cleaning device 9 for the intermediate transfer belt 8, and the driven roller 8 d serves as a tension roller that adjusts the tension of the intermediate transfer belt 8.

  Subsequently, in the image forming apparatus 1 configured as described above, the presence or absence of alumite treatment (insulation treatment) on the surfaces of the driven rollers 8 b to 8 d that support the intermediate transfer belt 8 is caused by scratches generated on the back surface of the intermediate transfer belt 8. The effect on the occurrence of streak-like image defects will be described with reference to FIG. FIG. 3 is a graph showing the effect of the presence or absence of the alumite processing of the driven roller on the occurrence of streak-like image defects.

  The occurrence of streak-like image defects was checked every time 50,000 sheets were printed, and the number of streaks that appeared on the image was counted visually.

  According to FIG. 3, when the surface of the driven rollers 8b to 8d is not anodized, as many as 5 streak image defects have already occurred after printing 50,000 sheets, and 20 after printing 300,000 sheets. The book has been reached. On the other hand, when alumite treatment was applied to the surfaces of the driven rollers 8b to 8d, even after printing 300,000 sheets, the occurrence of streak-like image defects could be suppressed to only one, which was a good result.

  Therefore, in order to prevent the occurrence of a streak-like image defect due to scratches occurring on the back surface of the intermediate transfer belt 8, the surface of the driven rollers 8b to 8d that support the intermediate transfer belt 8 is alumite that is an insulating treatment. It is desirable to perform processing. In addition, since the slip of the intermediate transfer belt 8 can be prevented by subjecting any one of the driven rollers 8b to 8d to an alumite treatment, the same operations and effects as described above can be obtained.

  Next, the influence of the thickness of the insulating layer on the surfaces of the driven rollers 8b to 8d supporting the intermediate transfer belt 8 due to the alumite treatment on the deterioration of the intermediate transfer belt 8 and the cleaning performance for the intermediate transfer belt 8 will be described with reference to FIG. And it demonstrates using FIG. FIG. 4 is a graph showing the influence of the thickness of the insulating layer due to the alumite treatment of the driven roller on the volume resistivity of the intermediate transfer belt, and FIG. 5 similarly shows the influence on the bias current-voltage characteristics during the intermediate transfer belt cleaning. It is a graph to show.

  Note that the deterioration of the intermediate transfer belt 8 shown in FIG. 4 was evaluated by measuring the volume resistivity of the intermediate transfer belt 8 after completion of printing 300,000 sheets. Further, the cleaning performance for the intermediate transfer belt 8 shown in FIG. 5 was evaluated by measuring the current-voltage characteristics by applying a bias current when the intermediate transfer belt 8 was cleaned by the cleaning device 9.

  According to FIG. 4, when the thickness of the insulating layer on the surface of the driven rollers 8b to 8d exceeds 20 μm, the volume resistivity of the intermediate transfer belt 8 is abrupt when many printings of 300,000 sheets are executed. It can be seen that it is rising. On the other hand, when the thickness of the insulating layer by the alumite treatment is 20 μm or less, an increase in volume resistivity of the intermediate transfer belt 8 can be suppressed, which is a good result.

  Therefore, in order to prevent an increase in the volume resistivity that deteriorates the intermediate transfer belt 8, the thickness of the insulating layer on the surfaces of the driven rollers 8b to 8d that support the intermediate transfer belt 8 by anodizing is set to 20 μm or less. It is desirable.

  Further, according to FIG. 5, when the thickness of the insulating layer formed by alumite treatment on the surfaces of the driven rollers 8b to 8d is 23 μm, the voltage is remarkably increased with respect to the bias current applied when cleaning the intermediate transfer belt 8. That is, it can be seen that the electrical resistance increases, which may adversely affect cleaning. On the other hand, when the thickness of the insulating layer by the alumite treatment was 20 μm, the voltage with respect to the bias current was almost the same as that when the alumite treatment was not performed, and the result was good.

  Therefore, in order to maintain the cleaning performance for the intermediate transfer belt 8 normally, it is desirable that the thickness of the insulating layer on the surfaces of the driven rollers 8b to 8d supporting the intermediate transfer belt 8 by anodizing is 20 μm or less. It is.

  In this way, an intermediate transfer belt 8 that is an intermediate transfer member that once carries a toner image, and a plurality of support rollers around which the intermediate transfer belt 8 is wound, and a driving roller 8a that transmits a rotational force, In the image forming apparatus 1 including the driven rollers 8b to 8d that rotate according to the rotation of the intermediate transfer belt 8, the driven rollers 8b to 8d are subjected to insulation treatment on the surface, so that the driven rollers 8b to 8d are charged. It becomes easy to do. As a result, an electrostatic force acts between the intermediate transfer belt 8 and the driven rollers 8b to 8d, and the driven rollers 8b to 8d are attracted to the back surface of the intermediate transfer belt 8. Therefore, it is possible to prevent slip between the intermediate transfer belt 8 and the driven rollers 8b to 8d while suppressing an increase in cost without being adversely affected by heat. As a result, the occurrence of scratches on the back surface of the intermediate transfer belt 8 can be suppressed, the transfer performance of the toner image from the photosensitive drum 21 to the intermediate transfer belt 8 is improved, and high-quality image formation is performed. An image forming apparatus 1 capable of performing the above can be obtained.

  In addition, since the insulation treatment of the surfaces of the driven rollers 8b to 8d is alumite treatment, the surfaces of the driven rollers 8b to 8d can be hardened in addition to easy insulation treatment. As a result, slippage between the intermediate transfer belt 8 and the driven rollers 8b to 8d can be prevented by the action of electrostatic force, and the hardness of the surface of the driven rollers 8b to 8d can be increased. It is possible to further enhance the effect of suppressing the occurrence of scratches on the back surface of the.

  Moreover, since the thickness of the insulating layer formed by alumite treatment on the surfaces of the driven rollers 8b to 8d is 20 μm or less, it is possible to suppress an increase in electrical resistance of the driven rollers 8b to 8d. As a result, the volume resistivity of the intermediate transfer belt 8 is increased even after a very large amount of printing is performed with respect to the driven roller 8c disposed opposite to the cleaning device 9 for the intermediate transfer belt 8. And the deterioration of the intermediate transfer belt 8 can be prevented. Even when a bias current is applied during cleaning, it is possible to normally clean the toner remaining on the surface of the intermediate transfer belt 8. Accordingly, the surface of the driven rollers 8b to 8d is insulated while preventing the deterioration of the intermediate transfer belt 8 and the deterioration of the cleaning performance for the intermediate transfer belt 8, so that the intermediate transfer belt 8 and the driven rollers 8b to 8d are separated from each other. Slip can be prevented.

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

  For example, the image forming apparatus 1 used for the description in the above embodiment is a model including three driven rollers that support the intermediate transfer belt 8, but may be a model including one or four or more rollers. Further, as described above, any one of the plurality of driven rollers is alumite-treated to prevent the intermediate transfer belt 8 from slipping, so that the same operation and effect as in the above embodiment can be obtained. it can.

  The present invention can be used in an image forming apparatus that includes an intermediate transfer member and at least one driven roller that rotates according to the rotation of the intermediate transfer member.

1 is a schematic vertical sectional front view of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a partially enlarged vertical sectional view around an intermediate transfer belt of the image forming apparatus shown in FIG. 1. It is a graph which shows the influence which the presence or absence of the alumite process of a driven roller has on generation | occurrence | production of a streak-like image defect. 6 is a graph showing the influence of the thickness of the insulating layer by the alumite treatment of the driven roller on the volume resistivity of the intermediate transfer belt. 6 is a graph showing the influence of the thickness of an insulating layer formed by alumite treatment of a driven roller on bias current-voltage characteristics during intermediate transfer belt cleaning.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Main body 8 Intermediate transfer belt (intermediate transfer body)
8a Drive roller 8b to 8d Driven roller 9 Cleaning device 20 Image forming part 21 Photosensitive drum (image carrier)
30 Primary transfer section 31 Primary transfer roller

Claims (3)

An intermediate transfer member that once carries a toner image, a plurality of support rollers around which the intermediate transfer member is wound, a driving roller that transmits rotational force, and at least one driven member that rotates according to the rotation of the intermediate transfer member In an image forming apparatus comprising a roller,
An image forming apparatus, wherein at least one of the driven rollers has an insulating surface.   The image forming apparatus according to claim 1, wherein the insulating process is an alumite process.   The image forming apparatus according to claim 2, wherein the insulating layer formed by the alumite treatment has a thickness of 20 μm or less.

Images