JP5288030B2 - Image forming apparatus - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a facsimile machine, and a printer, and a transfer device used therefor, and more particularly to improvement of a transfer roller urging means of a transfer device for an image forming apparatus.

2. Description of the Related Art Conventionally, a transfer device that urges a transfer roller attachment / detachment unit configured to be detachable from an image forming apparatus main body toward a side of an intermediate transfer belt by a push spring (coil spring) is known (for example, Patent Document 1) ).
This patent document 1 discloses that a static elimination needle is attached to a support member (holder case), and an electrical contact of the static elimination needle is urged in the axial direction of the transfer roller by a conductive elastic member. In the transfer apparatus (and image forming apparatus) described in No. 1, the transfer roller is pressed against the intermediate transfer belt 2 by urging the transfer roller support member (holder case) with two right and left push springs. A next transfer nip is formed (see FIGS. 1 to 5 of Patent Document 1). As described above, in a transfer apparatus in which a part of the structure can be attached to and detached from the apparatus main body, a transfer nip is generally formed by pressing a case of a detachable unit including a transfer roller with a pressing spring.

JP 2006-30540 A

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that improves the urging means of a transfer roller so that there is no variation in transfer pressure, and hence the image quality of a transferred image is good.

In order to solve the above-mentioned problems, an invention according to claim 1 is directed to an image carrier that carries an image on a surface, a transfer roller that forms a transfer nip between the image carrier, and both ends of the transfer roller. A pair of bearings for receiving the shaft, a slide mechanism capable of sliding the pair of bearings in a direction in which the transfer roller contacts and separates from the image carrier, and an urging means for biasing the transfer roller toward the image carrier. And the urging means has one tensile elastic material or a plurality of tensile elastic materials connected in series, and a pair of rotational pressing materials connected to both ends of the tensile elastic material. Each of the pair of rotation pressing materials has one end connected to the tensile elastic material, and the other end having a contact surface orthogonal to the direction in which the transfer roller contacts the image carrier and the corresponding contact surface. The pair of rotations in contact with the bearing and the tensile elastic material By pulling one end of圧材each other, the pair of bearings in the axial direction be perpendicular and in the direction toward and away from by rotating the rotating pressing member about a vertical rotation axis of the transfer roller It is characterized by pressing toward the image carrier .

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the rotation shaft is provided at a position opposite to the image carrier with the transfer roller interposed therebetween .

According to a third aspect of the present invention, there is provided an intermediate transfer belt which is supported by a plurality of rollers and carries an image transferred from a latent image carrier on its surface, and a transfer nip formed between the intermediate transfer belt and the intermediate transfer belt. A roller, a pair of bearings for receiving shafts at both ends of the transfer roller, a slide mechanism capable of sliding the pair of bearings in a direction in which the transfer roller contacts and separates from the intermediate transfer belt, and the transfer roller for the intermediate transfer comprising biasing means for urging the belt direction, wherein the biasing means includes a single tensile elastic material or series connected plurality of tensile elastic material, both ends connected to the pair of the tensile elastic material Each of the pair of rotary pressing materials has one end connected to the tensile elastic material and the other end orthogonal to the direction in which the transfer roller contacts the intermediate transfer belt. With a contact surface The abutting surface abuts said bearing, one end of the tension of the pair of rotating pressing member with elastic material by the pulling each other, perpendicular to the axis direction be perpendicular and in the direction toward and away from said transfer roller A rotating pressing member is rotated about a rotating shaft to press the pair of bearings toward the intermediate transfer belt .

According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect, the rotation shaft is provided at a position opposite to the intermediate transfer belt with the transfer roller interposed therebetween .

According to a fifth aspect of the present invention, in the image forming apparatus according to the third or fourth aspect, the transfer roller is in contact with the intermediate transfer belt at a position facing one of the plurality of rollers. The transfer nip is formed .

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 tensile elastic material is disposed substantially parallel to the axis of the transfer roller.

According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects, the recording material is provided at a position upstream of the transfer nip in the recording material conveyance direction, and guides the recording material to the transfer nip. A guide member is provided .

According to an eighth aspect of the present invention, in the image forming apparatus according to the seventh aspect, the transfer guide member is inclined with respect to the conveyance path of the recording material .

According to a ninth aspect of the present invention, in the image forming apparatus according to any one of the first to eighth aspects, the slide mechanism is provided so as to extend in the contacting / separating direction and is capable of sliding the bearing. It is characterized by having .

According to a tenth aspect of the present invention, in the image forming apparatus according to any one of the first to ninth aspects, the charge of the recording material after transfer is provided at a position downstream of the transfer nip in the recording material conveyance direction. A neutralizing member for neutralizing is provided .

According to the present invention, even if there is a precision error or variation in the biasing means, the transfer pressure in the transfer nip can be made uniform without variation, and therefore the image quality of the transferred image can be improved. be able to.

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

  FIG. 1 is a configuration explanatory diagram showing a schematic configuration of the entire image forming apparatus according to an embodiment of the present invention. Reference numeral 1 in the figure denotes a quadruple tandem type intermediate transfer type image forming apparatus, which includes an exposure unit 2, an image forming unit 3, a transfer device 4, a paper feeding device 5, a fixing device 6, and a waste. The toner storage unit 7 and a paper discharge unit 8 are included.

  The exposure unit 2 is provided with light emitting means (not shown) such as a laser diode and a light emitting diode, and each photosensitive drum Y, M, which is a latent image carrier uniformly charged by a charging means described later. The surface of C and K is selectively exposed by light emitting means based on image information separated into predetermined colors to form an electrostatic latent image.

  The image forming unit 3 includes four image forming units 3a, 3b, 3c, and 3d provided for each color. Each image forming unit is an image carrier arranged in the order of yellow, magenta, cyan, and black image forming. Four photosensitive drums Y, M, C, and K, and a charging unit, a developing unit, a photosensitive unit cleaning unit, and the like (not shown) provided around the unit are integrated.

  The transfer device 4 includes an intermediate transfer belt 40 formed of an endless belt that is an intermediate transfer member (image carrier), two stretching rollers (41, 42) that support and stretch the intermediate transfer belt 40, and 4 The primary transfer rollers 43, 44, 45, 46, a secondary transfer unit 47, a cleaning unit 48 that is a cleaning unit for the intermediate transfer belt 40, and the like. One of the stretching rollers is a driving roller 41 that drives the intermediate transfer belt 40, and a tension roller 42 as a driven roller. The primary transfer rollers 43, 44, 45, and 46 take into account the gap discharge and the like, so that the photosensitive drums Y, M, C, and K and the intermediate transfer belt 40 are opposed to each other with the intermediate transfer belt 40 therebetween. It is arranged at a position slightly shifted downstream in the transport direction and is connected to a bias power source (not shown) so that a transfer bias is applied from the back surface (inner peripheral surface) of the intermediate transfer belt 40. The secondary transfer unit 47 includes a secondary transfer roller 49 and a holder case 47a that rotatably supports the secondary transfer roller. The secondary transfer unit 47 is disposed at a position facing the drive roller 41 and the intermediate transfer belt 40. Thus, the intermediate transfer belt 40 and the secondary transfer roller 49 are pressed against each other on the outer periphery of the driving roller 41 to form a secondary transfer nip. The secondary transfer unit 47 will be described in detail later. The cleaning unit 48 also has a cleaning blade 48a that can be brought into contact with and separated from the outer surface of the intermediate transfer belt 40 on the outer periphery of the driving roller 41. This is a blade-type cleaning unit that causes the cleaning blade 48a to come into contact with the intermediate transfer belt 40 and scrape off. Note that a separate backup roller may be provided instead of a configuration in which the blade is brought into contact with and separated from the outer periphery of the drive roller 41.

  The paper feeding device 5 is in pressure contact with the stocked recording material 50 for storing and stocking recording materials such as copy paper and OHP sheets, and the stocked recording material, and is controlled by a control means (not shown). The sheet feeding roller 51 feeds the recording material one by one to the conveying path based on the signal, and a registration roller pair 52 that adjusts the timing for conveying the recording material to the transfer nip.

  The fixing device 6 includes a fixing roller 60, a pressure roller 61, and the like, and urges the pressure roller 61 against the fixing roller 60 by an urging means (not shown) to form a fixing nip. Then, in the fixing nip, the carried toner is applied to the conveyed recording material by applying heat from a heating means (not shown) provided in the fixing roller 60 and pressure of the pressure roller 61 by the biasing means. The image is fixed on the recording material.

  The waste toner storage unit 7 is provided with a waste toner collection box 70. Waste toner scraped off by a photoreceptor cleaning unit (not shown), the intermediate transfer belt cleaning unit 48, and the like is stored in the waste toner collection box 70. It is configured to be carried and accommodated by a conveying means (not shown) such as a conveying screw. Further, the waste toner collection box 70 is replaced with an empty box during maintenance or the like, and the waste toner is collected.

  The paper discharge unit 8 includes a paper discharge tray 80 and a paper discharge roller pair 81 formed on the uppermost part of the image forming apparatus 1. The recording material on which the image has been fixed by passing through the fixing device 6 is removed from the conveyance path. The paper is discharged by a pair of paper discharge rollers 81 and stacked on a paper discharge tray 80.

  Next, the secondary transfer unit 47 that is a main part of the transfer apparatus according to the embodiment of the present invention will be described in detail with reference to FIGS. FIG. 2 is a perspective view showing the appearance of the secondary transfer unit of the transfer apparatus according to the embodiment of the present invention. As described above, as shown in FIG. 2, the secondary transfer unit 47 is mainly composed of a secondary transfer roller 49 as a transfer roller and a holder case 47a as a case member. The secondary transfer roller 49 is disposed at a position facing the drive roller 41 and the intermediate transfer belt 40, and is pressed against the intermediate transfer belt 40 on the outer periphery of the drive roller 41 to form a secondary transfer nip (see FIG. 1). The secondary transfer roller 49 is electrically connected to a bias power source (not shown), and applies a transfer bias having a polarity opposite to the charging polarity of the toner image carried by the intermediate transfer belt 40 from the back surface of the recording material at the secondary transfer nip. Thus, a transfer electric field is formed, and the toner image is transferred from the intermediate transfer belt 40 to the recording material using electrostatic attraction.

  As shown in FIG. 2, the holder case 47a is formed in a substantially casing shape that covers the periphery of the secondary transfer roller 49, and the secondary transfer roller 49 serving as the secondary transfer nip contacts the intermediate transfer belt 40. The vicinity of the surface is an opening 47b that opens in a rectangular shape. The side of the secondary transfer nip of the holder case 47a below the opening 47b, that is, upstream of the secondary transfer nip in the recording material conveyance direction (see FIG. 1) serves as a pre-transfer guide 47c, and the opening 47b. On the side of the secondary transfer nip of the holder case 47a on the downstream side in the recording material conveyance direction (see FIG. 1), a static elimination needle 47d, which is a self-discharge type static elimination member utilizing corona discharge, is attached. .

  This pre-transfer guide 47c has a substantially rectangular plate shape in which the axial direction of the secondary transfer roller 49 is the longitudinal direction, and is inclined at a predetermined angle with respect to the conveyance path so as to guide the recording material to the secondary transfer nip. (See FIG. 1). Therefore, even if the recording material is conveyed on the conveying path by driving the registration roller pair 52 (see FIG. 1) and the leading edge of the recording material hits the pre-transfer guide 47c, the pre-transfer guide 47c is predetermined with respect to the conveying path. Since the angle is inclined, the recording material can be smoothly guided to the secondary transfer nip.

  Further, the static elimination needle 47d is arranged in parallel along the axial direction of the secondary transfer roller 49 so that the tip of the needle is close to the conveyance path of the recording material after the secondary transfer. It is grounded, so that the charge staying on the surface of the recording material after the secondary transfer can be reduced. For this reason, it is possible to prevent the recording material from being affected by static electricity and being unable to properly separate the recording material from the secondary transfer roller 49 and the intermediate transfer belt 40 (see FIG. 1) and being jammed or the transfer position being shifted. it can.

  Further, a slide mechanism is provided on both end surfaces 47e (47e ′) in the axial direction of the holder case 47a, and both shaft ends of the secondary transfer roller 49 can be rotated by bearings 49a (49a ′) via the slide mechanism. I support it. In addition, positioning projections 47f and 47g (47f 'and 47g') are provided on both end faces 47e (47e ') so as to protrude outwardly in two upper and lower stages so as to sandwich the bearing 49a (49a'). A pressing spring S is attached to each of the positioning protrusions 47f and 47g (47f ′ and 47g ′).

Next, the slide mechanism and biasing means of the secondary transfer unit will be described in detail. FIG. 3 is a partial cross-sectional perspective view mainly showing the sliding mechanism of the secondary transfer unit of FIG. 2, and FIG. 4 is a partial cross-sectional perspective view mainly showing the urging means of the secondary transfer unit of FIG.
As shown in FIG. 3, the secondary transfer unit 47 allows the bearing 49a (49a ′) to slide relative to the holder case 47a so that the secondary transfer roller 49 contacts and separates from the intermediate transfer belt 40. It has a configured slide mechanism. This slide mechanism includes a long hole 47h (47h ') provided on each of both end faces 47e (47e'), and a bearing 49a (49a ') that holds the long hole 47h (47h') from both sides. The long hole 47h (47h ') is configured to pass through the shaft of the secondary transfer roller 49, and the shaft passes through the bearing 49a (49a') in the direction of arrow A in the drawing, that is, with the intermediate transfer belt 40. It is slidably held in the direction of contact and separation. 3 and 4 show the horizontal plane passing through the long hole 47h (47h ') and the oblique lines in the figure so that the relationship between the secondary transfer roller 49, the bearing 49a (49a'), and the end face 47e (47e ') can be easily understood. This is a state where only the holder case 47a is cut at the portion indicated by the part. Further, the long hole 47h (47h ′) may be formed in a slit shape with a groove formed on the secondary transfer nip side.

Further, the secondary transfer unit 47 has a biasing means in the holder case 47a for biasing the secondary transfer roller 49 toward the secondary transfer nip, that is, the drive roller 41. As shown in FIGS. 3 and 4, the urging means includes a tension spring 47i made of a single coil spring that is a tension elastic material, and an arm material that is a pair of left and right rotational pressing materials connected to both ends. 47j (47j ′). The arm material 47j (47j ′) is rotatable by a pin 47l (47l ′) on the upper surface of the end surface 47e (47e ′) of the back surface 47k, which is the surface opposite to the secondary transfer nip side of the holder case 47a. The inner arm 47m on the right side in the drawing and the inner arm 47m ′ (not shown) on the opposite side are connected by a tension spring 47i, and the outer arm 47n (47n ′) is a bearing 49a ( 49a '). For this reason, the tension force of the tension spring 47i is always acting in the direction of arrow B (reverse direction on the left side not shown), and when the inner arm 47m is pulled in the direction of arrow B, the connection point between the tension spring 47i and the pin 47l Is a predetermined distance away from each other, so that moment force acts, the arm material 47j (47j ′) rotates in the direction of arrow C, and the outer arm 47n (47n ′) moves to the bearing 49a (49a ′) of the secondary transfer roller 49. Is pressed to the secondary transfer nip side indicated by the arrow D direction, that is, the drive roller 41 side, and the secondary transfer roller 49 is pressed against the intermediate transfer belt 40 on the outer periphery of the drive roller 41 to form a secondary transfer nip. It has become.
At this time, the two left and right inner arms 47m and 47m ′, which are one end of the arm member 47j (47j ′), are pulled together by one tension spring 47i. The pressing force by which the outer arms 47n and 47n ′ press both bearings 49a and 49a ′ of the secondary transfer roller 49 toward the drive roller 41 becomes equal.

Further, the biasing means is configured as described above to temporarily convert the tension force of the tension spring 47i into moment force to generate a pressure contact force of the secondary transfer nip. Since the direction in which the force is applied can be changed, it is not necessary to provide a spring along the direction in which the roller is pressed. Therefore, the tension spring 47i can be arranged in a dead space between the secondary transfer roller 49 arranged along the horizontal plane and the pre-transfer guide 47c arranged in an up-and-down inclination, and the space is effective. It can be used now. For this reason, size reduction of the whole apparatus can be achieved. Since the tension spring 47i is disposed substantially parallel to the axis of the secondary transfer roller 49, the length direction of the spring is the axis direction of the secondary transfer roller 49 having a relatively large space, A long spring with a small spring constant can be used. Therefore, fine adjustment of the transfer pressure is facilitated, and the image quality of the transferred image can be improved.
The tension spring 47i is a single coil spring, but a plurality of tension springs may be connected in series. The present invention is not limited to the coil spring, and a rubber material made of a leaf spring or a synthetic resin. It is obvious that the same effect can be obtained even in such a case.

Next, the positioning protrusion of the secondary transfer unit will be described in detail. 5 is a perspective view showing the positional relationship between the intermediate transfer belt and the secondary transfer unit when the transfer device of FIG. 2 is mounted, and FIG. 6 shows the positional relationship of FIG. 5 from the back side of the secondary transfer unit. FIG. 6 is a perspective view of the holder case cut along the hatched portion. The back side refers to the back 47j side of the holder case 47a.
As shown in FIGS. 5 and 6, the positioning projections 47f and 47g are projections having a substantially T-shaped cross section, and the back surfaces are flat plate surfaces f1 and g1, respectively. Secondary transfer from the flat plate surfaces f1 and g1 is performed. A push spring S made of a coil spring is attached to the boss in the opposite direction to the nip (drive roller 41), that is, on the back side. The positioning protrusions 47f and 47g have engaging surfaces f2 and g2 with triangular protrusions on the side of the driving roller 41, and the secondary transfer of the support member 4a that supports the driving roller 41 corresponding to the positioning protrusions 47f and 47g. Since the nip side surfaces are engaging surfaces 4b and 4c having a V-shaped cross section, when the cover of the apparatus main body (not shown) is closed, the pressing spring S is compressed and the positioning protrusions 47f and 47g are pressed by the pressing spring S. By being pressed against the engagement surfaces 4b and 4c by pressure, the engagement surfaces 4b and 4c engage with the engagement surfaces f2 and g2 of the positioning projections 47f and 47g, respectively, and the secondary transfer unit 47 is attached to the apparatus main body. Proper positioning at the time is made. Therefore, since the removable transfer unit 47 is always mounted at an appropriate position during image formation, the transfer position at the time of transfer is also accurate, and the image quality of the transferred image is improved. The other end face (not shown) has the same configuration.

  As described above, the secondary transfer unit of the transfer apparatus according to the embodiment of the present invention has been described. As described above, the means for urging the desorption unit is a tension that determines the transfer pressure in the secondary transfer nip. Since the biasing means by the spring and the pressing spring S for mounting and positioning the secondary transfer unit are separated, the transfer pressure is finely adjusted by the biasing means by the tension spring, and the pressing spring S is used only for positioning. It got better. For this reason, the push spring S can be improved as long as it can generate a certain pressing force. Therefore, a strong and short spring having a large spring constant can be used, and the configuration is such that the unit is not pressed directly from the back surface but pressed via the positioning protrusions 47f and 47g provided on the end surface of the unit. The width direction (the left-right direction in FIG. 1) can be reduced.

  Next, an outline of the operation of the image forming apparatus 1 will be described by taking a case where a full color image is formed as an example. The exposure unit 2 performs optical writing on the four image forming units 3a, 3b, 3c, and 3d, and electrostatic latent images of the respective colors are formed on the outer peripheral surfaces of the photosensitive drums Y, M, C, and K. In each of the image forming units 3a, 3b, 3c, and 3d, the electrostatic latent image is developed by the developing unit, and a monochromatic toner image is formed on each photosensitive drum. Then, a charge having the opposite polarity to the charged polarity of the toner image is applied by the primary transfer rollers 43, 44, 45, and 46 in the primary transfer nip of each color to form a transfer electric field, and the toner image is transferred to each photosensitive drum. To the intermediate transfer belt 40. In this way, a single color toner image is superimposed on the outer surface of the intermediate transfer belt 40 to form a full color toner image. The full-color toner image is driven to rotate by the driving roller 41 while being carried on the outer surface of the intermediate transfer belt 40, and reaches the secondary transfer nip. The recording material stocked in the paper feed cassette 50 is fed by the paper feed roller 51 and conveyed by the registration roller pair 52 at the conveyance timing. At the secondary transfer nip, a charge having a polarity opposite to the charged polarity of the toner image is applied by the secondary transfer roller 49 and transferred from the intermediate transfer belt 40 to the recording material. Thereafter, heat and pressure are applied by the fixing device 6 to be fixed as an image on the recording material, and the paper is discharged onto the paper discharge tray 80 by the paper discharge roller pair 81 and stocked. Further, the transfer residual toner on the intermediate transfer belt 40 is removed from the intermediate transfer belt 40 by the cleaning unit 48 and accumulated in the waste toner collection box 70. In the case of a monochrome image, only the corresponding image forming unit operates in the same manner.

As described above, the four-tandem type indirect transfer system is described as an example of the image forming apparatus according to the embodiment of the present invention. However, the image forming apparatus is not necessarily limited to this, and for example, a direct transfer system is used. It doesn't matter. In short, an image carrier (photosensitive belt, photosensitive drum, intermediate transfer belt, etc.) that carries an image on the surface, a transfer roller that forms a transfer nip with the image carrier, and the periphery of the transfer roller An image forming apparatus comprising a transfer device configured to be removably mounted together with the transfer roller from the main body of the apparatus. That's fine. In addition, the exposure unit, the sheet feeding device, the fixing device, the primary transfer unit, and the like are just examples, and other known devices and units can be employed. Even in that case, it is obvious that the same effect can be obtained.
In addition, the shape, structure, etc. of each component shown in the drawings show a preferable example to the last, and the design can be arbitrarily changed / modified within the scope described in the claims. is there.

1 is a configuration explanatory diagram illustrating a schematic configuration of an entire image forming apparatus according to an embodiment of the present invention; FIG. 2 is a perspective view illustrating an appearance of a secondary transfer unit of the transfer device according to the embodiment of the invention. It is a partial cutaway perspective view mainly showing a slide mechanism of the secondary transfer unit same as above. FIG. 3 is a partially cut perspective view mainly showing urging means of the secondary transfer unit of the above. FIG. 6 is a perspective view showing a positional relationship with an intermediate transfer belt when the secondary transfer unit is mounted on the apparatus main body. It is the perspective view which showed the positional relationship same as the above from the back side of the secondary transfer unit.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 4 Transfer apparatus 40 Intermediate transfer belt (Image carrier, intermediate transfer body)
41 Drive roller (stretching roller)
42 Tension roller
43 to 46 Primary transfer roller 47 Secondary transfer unit 47a Holder case (case member)
47c Pre-transfer guide 47d Static elimination needle (static elimination member)
47f, 47g, 47f ', 47g' Positioning projections 47h, 47h 'Long holes 47i, 47i' Tension springs (tensile elastic materials)
47j, 47j 'arm material (rotating pressing material)
49 Secondary transfer roller (transfer roller)
49a, 49a 'Bearings Y, M, C, K Photosensitive drum (image carrier, latent image carrier)
S Push spring

Claims (10)

An image carrier that carries an image on the surface;
A transfer roller that forms a transfer nip with the image carrier;
A pair of bearings for receiving shafts at both ends of the transfer roller ;
A slide mechanism capable of sliding the pair of bearings in a direction in which a transfer roller contacts and separates from the image carrier;
And a biasing means for biasing the transfer roller to the image carrier direction,
The biasing means has one tensile elastic material or a plurality of tensile elastic materials connected in series, and a pair of rotational pressing materials connected to both ends of the tensile elastic material,
Each of the pair of rotational pressing materials has one end connected to the tensile elastic material, the other end having a contact surface perpendicular to the direction in which the transfer roller contacts the image carrier, and the corresponding contact surface is Abutting with the bearing, and pulling one end of the pair of rotation pressing members with the tensile elastic material, the rotation axis that is perpendicular to the axial direction of the transfer roller and perpendicular to the contact and separation direction is centered. image forming apparatus characterized by the rotating pressing member is rotated to press the pair of bearings to the image bearing member as. The image forming apparatus according to claim 1, wherein the rotation shaft is provided at a position opposite to the image carrier with the transfer roller interposed therebetween . An intermediate transfer belt supported by a plurality of rollers and carrying an image transferred from a latent image carrier on the surface;
A transfer roller that forms a transfer nip with the intermediate transfer belt ;
A pair of bearings for receiving shafts at both ends of the transfer roller ;
A slide mechanism capable of sliding the pair of bearings in a direction in which a transfer roller comes in contact with and separates from the intermediate transfer belt ;
And a biasing means for biasing the transfer roller to the intermediate transfer belt direction,
The biasing means has one tensile elastic material or a plurality of tensile elastic materials connected in series, and a pair of rotational pressing materials connected to both ends of the tensile elastic material,
Each of the pair of rotational pressing materials has one end connected to the tensile elastic material, the other end having a contact surface perpendicular to the direction in which the transfer roller contacts the intermediate transfer belt, and the corresponding contact surface is the Abutting with the bearing, and pulling one end of the pair of rotation pressing members with the tensile elastic material, the rotation axis that is perpendicular to the axial direction of the transfer roller and perpendicular to the contact and separation direction is centered. image forming apparatus characterized by pressing the pair of bearings to the intermediate transfer belt side by rotating the rotating pressing member as. The image forming apparatus according to claim 3, wherein the rotation shaft is provided at a position opposite to the intermediate transfer belt with the transfer roller interposed therebetween . 5. The image forming apparatus according to claim 3, wherein the transfer roller is in contact with the intermediate transfer belt at a position facing one of the plurality of rollers to form the transfer nip. 6. . The tensile elastic material, the image forming apparatus according to any one of claims 1 to 5, characterized in that it is arranged substantially parallel to the axis of the transfer roller. The image forming apparatus according to claim 1, further comprising a guide member that is provided at a position upstream of the transfer nip in a recording material conveyance direction and guides the recording material to the transfer nip . The image forming apparatus according to claim 7, wherein the transfer guide member is disposed to be inclined with respect to the conveyance path of the recording material . The image forming apparatus according to claim 1, wherein the slide mechanism has an elongated hole that extends in the contact / separation direction and that can slide the bearing . 10. The image forming apparatus according to claim 1, further comprising a charge eliminating member that is provided at a position downstream of the transfer nip in a recording material conveyance direction and neutralizes charges on the recording material after transfer. .

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