JP2015228003A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus configured to allow a power supply member to reliably follow transfer means, while preventing increase in space.SOLUTION: An image forming apparatus includes: an image carrier; transfer means which transfers a toner image formed on a surface of the image carrier to a recording medium; a power supply member which supplies power to the transfer means; first pressing means which presses the transfer means toward the image carrier; and second pressing means which presses the power supply member toward the transfer means in a direction crossing the pressing direction of the first pressing means. The first pressing means and the second pressing means are arranged in a superimposed manner in an axial direction of the transfer means and the power supply means.

Description

  The present invention relates to an image forming apparatus.

  A toner image is formed on a transfer material that is brought into contact with an image carrier that carries a toner image formed by an electrophotographic method at a transfer nip and a transfer bias current is applied from a transfer current applying unit that is in contact with the surface. In a transfer device in an image forming apparatus provided with a transfer roller for transferring a transfer roller, the transfer roller is configured by winding an ionic conductive material around a conductive axis, and the transfer current applying means prevents polarization in the ionic conductive material. For this reason, there is known a transfer device in which the transfer current applying means is arranged at a position where the transfer current from the transfer current applying means flows between the transfer nips via the transfer roller shaft core (Patent Document 1).

  An image bearing member on which a toner image corresponding to image information is formed or an intermediate transfer member to which a toner image formed on the image bearing member is transferred and a semiconductive layer that generates a transfer electric field on the surface are formed to record the toner image. On the extension line connecting the center of the transfer roller and the center of the nip formed by the transfer roller and the image bearing member, or the center of the nip formed by the transfer roller and the intermediate transfer member, and the center of the transfer roller There is also known an image forming apparatus that includes an electrode member that is arranged so that a contact point with the transfer roller comes on the downstream side, and applies a bias to the transfer roller (Patent Document 2).

JP-A-2005-316200 JP 2003-5539 A

  An object of the present invention is to provide an image forming apparatus capable of reliably following a power feeding member with respect to a transfer unit while suppressing an increase in space.

In order to solve the above-mentioned problem, an image forming apparatus according to claim 1,
An image carrier,
Transfer means for transferring a toner image formed on the surface of the image carrier to a recording medium;
A power supply member for supplying power to the transfer means;
First pressing means for pressing the transfer means toward the image carrier;
A second pressing unit that presses the power feeding member toward the transfer unit across the pressing direction of the first pressing unit;
It is characterized by that.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect,
The first pressing means and the second pressing means are arranged to overlap in the axial direction of the transfer means and the power feeding member,
It is characterized by that.

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect,
The first pressing means presses the transfer means on the downstream side in the transport direction of the recording medium including the transport direction of the recording medium on the upstream side in the transport direction of the recording medium;
It is characterized by that.

According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects,
The second pressing means includes a line imaginary connecting the center of curvature of the image carrier and the rotation center of the transfer means at a position where the power supply member contacts the transfer means, and the conveyance direction of the recording medium Pressing on the upstream side at
It is characterized by that.

The invention according to claim 5 is the image forming apparatus according to any one of claims 1 to 4,
A moving means for moving the transfer means along the pressing direction of the first pressing means from the image holding body to a retracted position not in contact with the image holding body;
The transfer means is moved to the retracted position by the moving means, and the pressing of the power supply member to the transfer means is released.
It is characterized by that.

According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects,
The power supply member is a cylindrical power supply roll that rotates in contact with the transfer means.
It is characterized by that.

According to the first and second aspects of the present invention, the space is smaller than the case where there is no second pressing means that presses the power feeding member toward the transfer means while crossing the pressing direction of the first pressing means. The power feeding member can be reliably driven with respect to the transfer means while suppressing an increase in the number of times.
According to the third aspect of the present invention, in the transfer nip region, the transfer unit is not pressed downstream in the recording medium conveyance direction including the recording medium conveyance direction on the upstream side in the recording medium conveyance direction. The recording medium can be stably nipped.
According to the fourth aspect of the present invention, the power feeding member is not pressed upstream in the recording medium conveyance direction with respect to a virtual line connecting the rotation axis of the image carrier and the rotation axis of the transfer unit. As compared with this, the transfer means can be surely pressed toward the image carrier.
According to the fifth aspect of the present invention, the deformation of the transfer unit during long-term storage is suppressed as compared with the case where the transfer unit is moved to the retracted position by the moving unit and the pressing of the power supply member to the transfer unit is not released. can do.
According to the sixth aspect of the present invention, power can be stably supplied to the transfer means.

2 is a schematic longitudinal sectional view showing an internal configuration of the image forming apparatus 1. FIG. 3 is a schematic cross-sectional view showing an internal configuration of a transfer device 50 including a secondary transfer roller 53 and a power supply roller 54. FIG. FIG. 4 is a schematic cross-sectional view of a main part showing a secondary transfer roller 53, a power supply roller 54, and a pressing mechanism. (A) is a perspective view of the secondary transfer roller 53, the power supply roller 54, and the pressing mechanism, and (b) is a schematic view in the axial direction. (A) is a schematic diagram showing a separation / contact mechanism as an example of a moving means for separating the secondary transfer roller 53 from the secondary transfer portion T along the first direction (R1), and (b) is a secondary transfer roller. FIG. 5 is a schematic view showing a state where 53 is separated from the secondary transfer portion T along the first direction (R1) and the pressure contact of the secondary transfer roller 53 is released.

Next, the present invention will be described in more detail with reference to the drawings with reference to embodiments and specific examples. However, the present invention is not limited to these embodiments and specific examples.
Also, in the description using the following drawings, it should be noted that the drawings are schematic and the ratio of each dimension and the like are different from the actual ones, and are necessary for the description for easy understanding. Illustrations other than the members are omitted as appropriate.
In order to facilitate understanding of the following description, in the drawings, the front-rear direction is the X-axis direction, the left-right direction is the Y-axis direction, and the up-down direction is the Z-axis direction.

(1) Overall Configuration and Operation of Image Forming Apparatus FIG. 1 is a schematic cross-sectional view showing the internal configuration of the image forming apparatus 1 according to this embodiment.
Hereinafter, the overall configuration and operation of the image forming apparatus 1 will be described with reference to the drawings.

  The image forming apparatus 1 includes a control device 10, a paper feeding device 20, a photosensitive unit 30, a developing device 40, a transfer device 50, and a fixing device 60. On the upper surface (Z direction) of the image forming apparatus 1, a discharge tray 1a for discharging and storing a sheet on which an image is recorded is formed.

  The control device 10 includes an image forming device control unit 11 that controls the operation of the image forming device 1, a controller unit 12 that prepares image data according to a print processing request, an exposure control unit 13 that controls lighting of the exposure head LH, It has a power supply device 14 and the like. The power supply device 14 applies a voltage to a charging roller 32, a developing roller 42, a primary transfer roller 52, and a power supply roller 54 as an example of a power supply member, which will be described later, and includes an exposure head LH, a paper supply device 20, a fixing device 60, and the like. Power is supplied to each sensor provided.

  The controller unit 12 converts print information input from an external information transmitting apparatus (for example, a personal computer) into image information for forming a latent image and outputs a drive signal to the exposure head LH at a preset timing. . The exposure head LH of the present embodiment is configured by an LED head in which a plurality of light emitting elements (LEDs) are linearly arranged along the main scanning direction.

  A paper feeding device 20 is provided at the bottom of the image forming apparatus 1. The sheet feeding device 20 includes a sheet stacking plate 21, and a plurality of sheets P as recording media are stacked on the upper surface of the sheet stacking plate 21. The paper P loaded on the paper stacking plate 21 and whose position in the width direction is determined by a regulating plate (not shown) is pulled out one by one from the top by the paper pulling unit 22 (−X direction), and then registered. It is conveyed to the nip portion of the pair 23.

  The photoconductor unit 30 includes a photoconductor drum 31 that is provided in parallel above the paper feeding device 20 (in the Z direction) and serves as an image carrier that is rotationally driven. A charging roller 32, an exposure head LH, a developing device 40, a primary transfer roller 52, and a cleaning blade 34 are arranged along the rotation direction of the photosensitive drum 31. A cleaning roller 33 for cleaning the surface of the charging roller 32 is disposed opposite to and in contact with the charging roller 32.

The developing device 40 includes a developing housing 41 in which a developer is accommodated. In the developing housing 41, a developing roller 42 disposed to face the photosensitive drum 31, and a pair of augers 44 that stir and convey the developer to the developing roller 42 side obliquely below the back side of the developing roller 42, 45 is arranged. A layer regulating member 46 that regulates the layer thickness of the developer is disposed in proximity to the developing roller 42.
Each of the developing devices 40 is configured in a similar manner except for the developer contained in the developing housing 41, and each forms a yellow (Y), magenta (M), cyan (C), and black (K) toner image. .

  The surface of the rotating photosensitive drum 31 is charged by the charging roller 32, and an electrostatic latent image is formed by the latent image forming light emitted from the exposure head LH. The electrostatic latent image formed on the photosensitive drum 31 is developed as a toner image by the developing roller 42.

  The transfer device 50 is formed by an intermediate transfer belt 51 as an example of an image carrier on which each color toner image formed on the photoconductive drum 31 of each photoconductive unit 30 is transcribed and the photoconductive unit 30. A primary transfer roller 52 for sequentially transferring (primary transfer) each color toner image to the intermediate transfer belt 51 is provided. Further, a secondary transfer roller 53, which is an example of a transfer unit that collectively transfers (secondary transfer) each color toner image transferred on the intermediate transfer belt 51 onto the paper P, and secondary transfer to the secondary transfer roller 53. The power supply roller 54 is an example of a power supply member that supplies power to the bias.

  Each color toner image formed on the photosensitive drum 31 of each photosensitive unit 30 is transferred to an intermediate transfer belt by a primary transfer roller 52 to which a predetermined transfer voltage is applied from a power supply device 14 or the like controlled by the image forming apparatus control unit 11. Electrostatic transfer (primary transfer) is sequentially performed on 51, and a superimposed toner image in which toners of respective colors are superimposed is formed.

  The superimposed toner image on the intermediate transfer belt 51 is conveyed to a region (secondary transfer portion T) where the secondary transfer roller 53 is disposed as the intermediate transfer belt 51 moves. When the superimposed toner image is conveyed to the secondary transfer unit T, the paper P is supplied from the paper feeding device 20 to the secondary transfer unit T in accordance with the timing. A predetermined transfer voltage is applied to the power supply roller 54 from the power supply device 14 or the like controlled by the image forming apparatus control unit 11, and the intermediate transfer is performed on the paper P that is fed from the registration roller pair 23 and guided by the conveyance guide. Multiple toner images on the belt 51 are collectively transferred.

  Residual toner on the surface of the photosensitive drum 31 is removed by the cleaning blade 34 and collected in the waste developer container. The surface of the photosensitive drum 31 is recharged by the charging roller 32. Residues that cannot be completely removed by the cleaning blade 34 and adhere to the charging roller 32 are captured and accumulated on the surface of the cleaning roller 33 that rotates in contact with the charging roller 32.

  The fixing device 60 includes a fixing unit 600, a conveyance roller pair 68, and a discharge roller pair 69. The fixing unit 600 includes a heating module 61 and a pressure module 62, and a fixing nip portion N (fixing area) is formed by a pressure contact area between the heating module 61 and the pressure module 62.

The sheet P on which the toner image is transferred in the transfer device 50 is conveyed to the fixing device 60 via the conveyance guide in a state where the toner image is not fixed. The toner image is fixed on the sheet P conveyed to the fixing device 60 by a pair of heating module 61 and pressure module 62 by the action of pressure bonding and heating.
The sheet P on which the fixing toner image is formed is discharged from the discharge roller pair 69 to the discharge tray 1 a on the upper surface of the image forming apparatus 1 via the conveyance roller pair 68.

(2) Configuration and Operation of Transfer Device FIG. 2 is a schematic sectional view showing the internal configuration of the transfer device 50 including the secondary transfer roller 53 and the power supply roller 54, and FIG. 3 shows the secondary transfer roller 53, the power supply roller 54, and the pressing mechanism. FIG. 4A is a perspective view of the secondary transfer roller 53, the power supply roller 54, and the pressing mechanism, and FIG. 4B is a schematic view in the axial direction.
Hereinafter, the configuration and operation of the transfer device 50 will be described with reference to the drawings.

(2.1) Configuration of Transfer Device As shown in FIG. 2, in the transfer device 50, an intermediate transfer belt 51 as an example of an image carrier is stretched around a drive roller DR and a support roller SR so as to be circulated and movable. Thus, it is supported by the primary transfer roller 52 from the back surface 51b side, and the front surface 51a side is arranged in contact with each photosensitive drum 31.
Further, the transfer device 50 includes an intermediate transfer belt cleaner 58 that removes residual toner and the like existing on the intermediate transfer belt 51.

  The intermediate transfer belt 51 is made of a resin such as polyimide or polyamide containing a suitable amount of a conductive agent such as carbon black, and is formed so that its volume resistivity is 106 to 1014 Ω · cm. The thickness is, for example, a film-like endless belt of about 0.1 mm.

The primary transfer unit includes primary transfer rollers 52 provided to face the respective photosensitive drums 31 with the intermediate transfer belt 51 interposed therebetween, and each primary transfer roller 52 has a voltage ( (Primary transfer bias) is applied. As a result, the toner images on the respective photosensitive drums 31 are sequentially electrostatically attracted to the intermediate transfer belt 51, and the toner images superimposed on the intermediate transfer belt 51 are formed.
The primary transfer roller 52 is, for example, a cylindrical shape having an outer diameter of 8 mm, and conventionally known metals such as SUS, iron, and aluminum can be used. In particular, the metal surface is plated with nickel, copper, chromium, or the like. Those are preferably used.

The secondary transfer unit is an example of a secondary transfer roller 53 that is disposed to face the driving roller DR with the intermediate transfer belt 51 interposed therebetween, and a power supply member that is rotatably contacted with the secondary transfer roller 53. The metal power supply roller 54 is used.
The power supply roller 54 is connected to the transfer bias power supply 140 of the power supply device 14 so as to supply the secondary transfer bias. The transfer bias power supply 140 generates the secondary transfer bias, and the generated secondary transfer bias is The toner is stably applied to the secondary transfer roller 53 via the power supply roller 54.

The secondary transfer roller 53 includes a shaft 53a and an elastic layer 53b fixed around the shaft 53a. The shaft 53a is a cylindrical bar made of a metal such as iron or SUS. The elastic body layer 53 b is made of, for example, a semiconductive rubber having a volume resistivity of 10 ⁶ to 10 ¹⁰ Ω · cm, and is disposed to face the driving roller DR via the intermediate transfer belt 51.
The secondary transfer roller 53 forms a secondary transfer portion T for secondary transfer of the toner image held by the intermediate transfer belt 51 together with the driving roller DR to the paper P conveyed from the paper feeding device 20.

  The driving roller DR is made of, for example, EPDM rubber dispersed with carbon, which can contact the inner surface of the intermediate transfer belt 51 to circulate and drive the intermediate transfer belt 51, and has a roller diameter of 28 mm. The hardness is set to 70 degrees (Asker C), for example. The drive roller DR is disposed in contact with the ground and serves as a counter electrode for the secondary transfer roller 53.

(2.2) Pressing mechanism of the secondary transfer roller 53 and the power feeding roller 54 As shown in FIG. 3, the secondary transfer roller 53 is rotatably supported at both ends of the shaft 53a by the first bearing member BR1. The first bearing member BR1 is supported in the secondary transfer portion T so as to be movable in a first direction that intersects the transport direction of the paper P.
In the secondary transfer roller 53, the first bearing member BR1 is pressed in the first direction (R1) by a pressure spring S1 as an example of a first pressing unit, and the intermediate transfer belt 51 is sandwiched therebetween. It is disposed in pressure contact with the drive roller DR, and forms a transfer nip area at the secondary transfer portion T.

As shown in FIG. 3, both ends of the power supply roller 54 are rotatably supported by the second bearing member BR <b> 2, and the second bearing member BR <b> 2 is secondary to the secondary transfer roller 53. Is supported so as to be movable in a second direction (R2) intersecting the first direction which is the pressing direction.
The power supply roller 54 is arranged in such a manner that the second bearing member BR2 is pressed in the second direction by a pressure spring S2 as an example of a second pressing unit and is rotatably contacted with the secondary transfer roller 53. Has been.

  The pressure spring S2 is pressed with a load (constant load) determined so as to be able to be driven and rotated by the secondary transfer roller 53 based on the hardness and outer diameter tolerance of the elastic layer 53b of the secondary transfer roller 53. . Therefore, compared with the constant displacement method in which the axis of the secondary transfer roller 53 and the power supply roller 54 is fixed and the power supply roller 54 is placed in contact, the power supply roller 54 is more elastic than the secondary transfer roller 53 of the power supply roller 54. The follower rotation can be stably performed without increasing the amount of biting into the body layer 53b.

FIG. 4 shows the arrangement of the pressing mechanism in the axial direction of the secondary transfer roller 53 and the power supply roller 54 (paper width direction orthogonal to the conveyance direction of the paper P).
As shown in FIG. 4, the secondary transfer roller 53 is rotatably supported at both ends of a shaft 53a by a first bearing member BR1, and the first bearing member BR1 is supported by a pressure spring S1 in a first direction. (Shown in FIG. 3: R1) and is pressed against the driving roller DR with the intermediate transfer belt 51 interposed therebetween.

  Both ends of the power supply roller 54 are rotatably supported by the second bearing member BR2, and the second bearing member BR2 is pressed in the second direction (illustrated in FIG. 3: R2) by the pressure spring S2. The secondary transfer roller 53 is disposed so as to be rotatable.

  The first direction (R1), which is the pressing direction of the pressure spring S1 of the secondary transfer roller 53, and the second direction (R2), which is the pressing direction of the pressure spring S2 of the power supply roller 54, are arranged to intersect. As shown in FIG. 4, the pressure spring S1 and the pressure spring S2 are arranged so as to overlap in the axial direction of the secondary transfer roller 53 and the power supply roller 54 (the paper width direction perpendicular to the conveyance direction of the paper P). ing.

As a result, both ends of the shaft 53a of the secondary transfer roller 53 are not extended to the outside of the pressure spring S2 that presses both ends of the power supply roller 54, and the second bearing member BR2 of the power supply roller 54 and the axial direction By overlapping and supporting, the increase in the axial space of the transfer device 50 can be suppressed.
Further, compared with a configuration in which both end portions of the shaft 53a are extended outside the pressure spring S2 that presses both end portions of the power supply roller 54, the occurrence of transfer failure due to bending due to the pressing of the secondary transfer roller 53 is reduced. Can be suppressed.

As shown in FIG. 3, the second direction (R2), which is the pressing direction of the power supply roller 54, is the center of curvature of the intermediate transfer belt 51 in the secondary transfer portion T with which the secondary transfer roller 53 contacts (the driving roller DR). The first direction that is the pressing direction of the secondary transfer roller 53 on the upstream side in the transport direction of the paper P, including the line L1 that connects the rotation center c1) and the rotational axis (c2) of the secondary transfer roller 53. It is set to cross the direction.
As a result, the second direction (R2), which is the pressing direction of the power supply roller 54 by the pressure spring S2, is in the transfer nip with respect to the first direction (R1) of the pressure spring S1 of the secondary transfer roller 53. Also has a pressure component to stabilize the transfer nip.

As shown in FIG. 3, the first direction (R1), which is the pressing direction of the secondary transfer roller 53 by the pressure spring S1, is the transport direction of the paper P on the upstream side of the transport direction of the paper P. Is set in a direction in which the sheet P containing the paper P is pressed downstream in the transport direction.
Therefore, in the transfer nip, for example, even when the sheet P receives a force in the pulling direction toward the downstream side in the sheet conveying direction due to the conveying force of the fixing device 60, the decrease in the pressing force in the direction orthogonal to the sheet conveying direction is suppressed. Thus, the transfer nip is stably formed.

(2.3) Separation and Contact Mechanism of Secondary Transfer Roller 53 FIG. 5A shows an example of a moving unit that separates the secondary transfer roller 53 from the secondary transfer portion T along the first direction (R1). FIG. 6B is a schematic diagram showing the separation / contact mechanism, in which FIG. 5B shows a state in which the secondary transfer roller 53 is separated from the secondary transfer portion T along the first direction (R1) and the pressure contact of the secondary transfer roller 53 is released. FIG. 6 is a schematic view (the release lever 55 is omitted).
In the separation / contact mechanism, for example, one end 55a is rotatably supported, and a first bearing member BR1 that supports both ends of the shaft 53a of the secondary transfer roller 53 is fitted in a long hole 55b formed on the other end. The release lever 55 is inserted.

As shown in FIG. 5A, the release lever 55 is rotated to the retracted position against the pressing direction in the first direction (R1) in which the first bearing member BR1 is pressed by the pressure spring S1. Thus, the secondary transfer roller 53 is separated from the secondary transfer portion T along the first direction (R1), and the pressure contact of the secondary transfer roller 53 is released.
The power supply roller 54 pressed against the secondary transfer roller 53 in the second direction (R2) by the pressure spring S2 moves the secondary transfer roller 53 as a facing member to the retracted position. It moves so as to protrude toward the secondary transfer portion T, and stops at a preset position where contact with the secondary transfer roller 53 is released (see FIG. 5B).

  By fixing the release lever 55 at the retracted position during distribution storage until the image forming apparatus 1 is shipped and installed, the release lever 55 is deformed at the transfer nip portion of the secondary transfer roller 53 and contacted with the power supply roller 54. The deformation of the elastic layer 53b of the secondary transfer roller 53 can be prevented.

  The release lever 55 is released from being fixed in the installation mode executed when the image forming apparatus 1 is initially installed, so that the secondary transfer roller 53 is pressed in the first direction by the pressure spring S1 and the intermediate transfer is performed. The belt 51 is placed in pressure contact with the driving roller DR. The power supply roller 54 is pressed in the second direction by the pressure spring S <b> 2 and is disposed in contact with the secondary transfer roller 53 so as to be rotatable.

(3) Action / Effect In the transfer device 50 according to the present embodiment, the first direction which is the pressing direction of the pressure spring S1 of the secondary transfer roller 53 and the pressing direction of the pressure spring S2 of the power supply roller 54 are shown. The pressure spring S <b> 1 and the pressure spring S <b> 2 are arranged so as to overlap each other in the axial direction of the secondary transfer roller 53 and the power supply roller 54.

  Therefore, the power supply roller 54 is pressed with a load (constant load) determined so as to be able to be driven and rotated by the secondary transfer roller 53, and the amount of biting of the power supply roller 54 into the elastic layer 53 b of the secondary transfer roller 53 is reduced. It can be driven and rotated stably without being excessive. Then, both ends of the shaft 53a of the secondary transfer roller 53 are supported without extending to the outside of the pressure spring S2 that presses both ends of the power supply roller 54, thereby increasing the axial space of the transfer device 50. Can be suppressed.

The power supply roller 54 connects the center of curvature of the intermediate transfer belt 51 (rotation center c1 of the driving roller DR) and the rotational axis (c2) of the secondary transfer roller 53 in the secondary transfer portion T in contact with the secondary transfer roller 53. Is set so as to intersect with the first direction which is the pressing direction of the secondary transfer roller 53 on the upstream side in the transport direction of the paper P including the virtual line L1.
Therefore, in the transfer nip, the pressing force of the power supply roller 54 by the pressure spring S2 also has a pressure component in the first direction (R1) by the pressure spring S1 of the secondary transfer roller 53, The transfer nip is stabilized.

Further, the first direction (R1), which is the pressing direction of the secondary transfer roller 53 by the pressure spring S1, is the sheet P including the transport direction of the sheet P upstream of the secondary transfer roller 53 in the transport direction of the sheet P. It is set in the direction of pressing to the downstream side in the transport direction.
Therefore, even when the paper P receives a force in the pulling direction toward the downstream side in the paper transport direction at the transfer nip, the reduction of the pressing force in the direction orthogonal to the paper transport direction is suppressed, and the transfer nip is stably formed. Is done.

  At the time of distribution storage until the image forming apparatus 1 is shipped and installed, the secondary transfer roller 53 is separated from the secondary transfer portion T in the first direction (R1), and the secondary transfer roller 53 is pressed. By fixing at the retracted position where the release is released, deformation of the secondary transfer roller 53 at the transfer nip and deformation of the elastic layer 53b of the secondary transfer roller 53 due to contact with the power supply roller 54 can be prevented. it can.

As mentioned above, although embodiment concerning this invention was explained in full detail, this invention is not limited to the said embodiment, A various change is made within the range of the summary of this invention described in the claim. Is possible.
For example, in this embodiment, an intermediate transfer type color image forming apparatus including an intermediate transfer belt is described as an example of an image holding member. However, a toner image held on a photosensitive drum as an example of an image holding member is transferred. The present invention can also be applied to a monochrome image forming apparatus that transfers to a recording medium using a transfer roller as a means.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 10 ... Control apparatus 20 ... Paper feed apparatus 30 ... Photoconductor unit 31 ... Photoconductor drum 40 ... Developing apparatus 50 ... Transfer apparatus 51 ... Intermediate transfer belt 52... Primary transfer roller 53... Secondary transfer roller 54... Feeding roller 55 .. release lever 60 .. fixing device DR .. driving roller BR1, BR2. Bearing member, second bearing member S1, S2 ... pressurizing spring

Claims (6)

An image carrier,
Transfer means for transferring a toner image formed on the surface of the image carrier to a recording medium;
A power supply member for supplying power to the transfer means;
First pressing means for pressing the transfer means toward the image carrier;
A second pressing unit that presses the power feeding member toward the transfer unit across the pressing direction of the first pressing unit;
An image forming apparatus. The first pressing means and the second pressing means are arranged to overlap in the axial direction of the transfer means and the power feeding member,
The image forming apparatus according to claim 1. The first pressing means presses the transfer means on the downstream side in the transport direction of the recording medium including the transport direction of the recording medium on the upstream side in the transport direction of the recording medium;
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The second pressing means includes a line imaginary connecting the center of curvature of the image carrier and the rotation center of the transfer means at a position where the power supply member contacts the transfer means, and the conveyance direction of the recording medium Pressing on the upstream side at
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. A moving means for moving the transfer means along the pressing direction of the first pressing means from the image holding body to a retracted position not in contact with the image holding body;
The transfer means is moved to the retracted position by the moving means, and the pressing of the power supply member to the transfer means is released.
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The power supply member is a cylindrical power supply roll that rotates in contact with the transfer means.
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.

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