JP2019020471A - Image formation device - Google Patents

Abstract

To prevent a transcriptional failure of toner at an area where a plurality of dots having different colors overlap when an a-Si photoreceptor is adopted.SOLUTION: A plurality of first photoreceptors 41a is arranged in sequence from the most upstream side in a predetermined direction D0. A second photoreceptor 41b is arranged at the most downstream side in the predetermined direction D0. A plurality of belt transcription rollers 441a forms a plurality of first nip sections N1 between the same and the plurality of first photoreceptors 41a through an intermediate transcription belt 440. A second belt transcription roller 441b forms a second nip section N2 between the same and the second photoreceptor 41b through the intermediate transcription belt 440. A width of a region, at each of the plurality of first nip sections N1, from a rotation center of each of the plurality of first photoreceptors 41a to an upstream side in the predetermined direction D0 is larger than the width of the region, at the second nip section N2, from the rotation center of the second photoreceptor 41b to the upstream side in the predetermined direction D0.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an image forming apparatus including an intermediate transfer belt and a plurality of belt transfer rollers.

  Generally, a tandem image forming apparatus includes four photosensitive members corresponding to four color toners, an intermediate transfer belt, and four belt transfer rollers. The intermediate transfer belt rotates in a stretched state. As a result, a part of the intermediate transfer belt moves in a predetermined traveling direction while being in contact with the surfaces of the four photosensitive members.

  The four belt transfer rollers form transfer nips at four locations between the four photoconductors and the intermediate transfer belt. In each of the transfer nips, a toner image is transferred from the photoreceptor to the intermediate transfer belt.

  Also, so-called Paschen discharge may occur in a region upstream of the transfer nip between each of the photoconductors and each of the belt transfer rollers in the traveling direction. Part of the toner carried by each of the photoconductors is transferred to the intermediate transfer belt earlier than the normal timing due to the Paschen discharge. As a result, so-called dot scattering occurs and image quality deteriorates.

  Further, in order to eliminate the problem of dot scattering, it is known that each of the belt transfer rollers is disposed on the downstream side in the traveling direction with respect to each of the photoconductors (see, for example, Patent Document 1). . Thereby, transferability can be ensured.

JP 2007-286270 A

  By the way, the a-Si photosensitive member has an amorphous silicon photosensitive layer. The a-Si photoreceptor has a higher dielectric constant than the organic photoreceptor. That is, in the a-Si photosensitive member, the charge amount of the electrostatic latent image is large. Therefore, each toner dot formed on the surface of the a-Si photosensitive member has a large thickness and a small area.

  Therefore, the toner image formed on the a-Si photosensitive member is a sharp image faithful to the electrostatic latent image. Further, when the a-Si photoreceptor is employed, the dot scattering due to the Paschen discharge is less likely to occur than when the organic photoreceptor is employed.

  On the other hand, in a portion where the toner dots of a plurality of colors overlap on the intermediate transfer belt, a transfer failure of toner dots transferred later may occur. This transfer failure is particularly remarkable when the a-Si photosensitive member is employed. The toner dot transfer failure leads to deterioration of the color balance of the output image.

  An object of the present invention is to provide an image forming apparatus capable of preventing toner transfer failure in a portion where dots of a plurality of colors overlap when an a-Si photosensitive member is employed.

  An image forming apparatus according to one aspect of the present invention includes a plurality of photoconductors, an intermediate transfer belt, and a plurality of belt transfer rollers. The plurality of photoconductors are rotating bodies on which toner images of different colors are formed on the surface. Each of the plurality of photoreceptors has a photosensitive layer of amorphous silicon. The plurality of photoconductors are arranged in parallel at intervals in a predetermined direction. The intermediate transfer belt is an annular member that is stretched around a plurality of supports and rotates while being in contact with the plurality of photoconductors. The plurality of belt transfer rollers are rotatably supported while being urged to the plurality of photoconductors via the intermediate transfer belt. Each of the plurality of belt transfer rollers has an elastic layer, and each of the toner images is transferred from the plurality of photoreceptors to the intermediate transfer belt by applying a transfer voltage. The plurality of photoconductors include a plurality of first photoconductors arranged in order from the most upstream side in the predetermined direction and a second photoconductor arranged on the most downstream side in the predetermined direction. The plurality of belt transfer rollers include a plurality of first belt transfer rollers facing the plurality of first photoconductors and a second belt transfer roller facing the second photoconductor. The plurality of first belt transfer rollers are arranged at positions where the respective rotation centers are shifted to the upstream side in the predetermined direction with respect to the respective rotation centers of the plurality of first photosensitive members. The rotation center of the second belt transfer roller is disposed at the same position in the predetermined direction or a position shifted to the downstream side in the predetermined direction with respect to the rotation center of the second photoconductor.

  According to the present invention, when an a-Si photoconductor is employed, it is possible to provide an image forming apparatus capable of preventing toner transfer failure in a portion where dots of a plurality of colors overlap.

FIG. 1 is a configuration diagram of an image forming apparatus according to an embodiment. FIG. 2 is a cross-sectional view of the belt transfer roller in the image forming apparatus according to the embodiment. FIG. 3 is a cross-sectional view of the intermediate transfer belt in the image forming apparatus according to the embodiment. FIG. 4 is a layout diagram of a plurality of photoconductors and a plurality of belt transfer rollers in the image forming apparatus according to the embodiment. FIG. 5 is a diagram illustrating a first belt transfer nip and a second belt transfer nip in the image forming apparatus according to the embodiment. FIG. 6 is an arrangement diagram of a plurality of photoconductors and a plurality of belt transfer rollers in the image forming apparatus according to the first reference example. FIG. 7 is a diagram illustrating the first belt transfer nip and the second belt transfer nip in the image forming apparatus according to the first reference example. FIG. 8 is a diagram illustrating the first belt transfer nip and the second belt transfer nip in the image forming apparatus according to the second reference example.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the following embodiment is an example which actualized this invention, Comprising: It does not have the character which limits the technical scope of this invention.

[Embodiment]
The image forming apparatus 10 according to the embodiment is an apparatus that executes a printing process for forming an image on a sheet by an electrophotographic method. The sheet is a sheet-like image forming medium such as paper or an envelope. The image forming apparatus 10 is a tandem color image forming apparatus.

[Configuration of Image Forming Apparatus 10]
As shown in FIG. 1, the image forming apparatus 10 includes a sheet supply mechanism 2, a sheet transport mechanism 3, an image forming unit 40, four supply units 5, and the like in the main body 1.

  The image forming unit 40 is an apparatus that executes the electrophotographic printing process. The image forming unit 40 includes four image forming units 4, an optical scanning device 46, a transfer device 44, and a fixing device 47.

  The four image forming units 4 correspond to toners of four colors of cyan, magenta, yellow, and black. Each of the image forming units 4 includes a drum-shaped photoreceptor 41, a charging device 42, a developing device 43, a drum cleaning device 45, and the like.

  That is, the image forming apparatus 10 includes four photoconductors 41, four charging devices 42, four developing devices 43, and four drum cleaning devices 45. In the present embodiment, each of the four photoconductors 41 is an a-Si photoconductor.

  Each of the photoconductors 41 includes a metal tube and a photosensitive layer mainly composed of amorphous silicon formed around the tube. More specifically, each of the photoconductors 41 includes the element tube made of aluminum and a plurality of layers formed around the element tube. The plurality of layers include a pressure-resistant layer, a blocking layer, the photosensitive layer, and a protective layer that are sequentially stacked from the inside.

  The transfer device 44 includes an intermediate transfer belt 440, four belt transfer rollers 441 corresponding to the four photoconductors 41, a sheet transfer roller 442, a belt cleaning device 443, and a plurality of stretching rollers 444.

  The intermediate transfer belt 440 is an annular belt member. The intermediate transfer belt 440 is stretched around a plurality of stretching rollers 444. At least one of the plurality of stretching rollers 444 is rotationally driven by a driving mechanism (not shown). As a result, the intermediate transfer belt 440 rotates while contacting the four photoconductors 41. The plurality of stretching rollers 444 are an example of a plurality of supports that rotatably support the intermediate transfer belt 440.

  As the intermediate transfer belt 440 rotates, the lower portion of the intermediate transfer belt 440 moves in a predetermined traveling direction D0. The four photoconductors 41 are arranged in parallel at intervals in the traveling direction D0. Similarly, the four belt transfer rollers 441 are also arranged in parallel at intervals in the traveling direction D0. The traveling direction D0 is an example of a predetermined direction.

  Three of the four photoconductors 41 corresponding to the three color toners are sequentially arranged from the most upstream side in the traveling direction D0, and one corresponding to the remaining black toner is disposed on the most downstream side in the traveling direction D0. Has been placed.

  For example, three photoreceptors 41 corresponding to yellow, cyan, and magenta toner 90 are arranged in order from the upstream side in the traveling direction D0.

  In the following description, the three photoconductors 41 arranged in order from the most upstream side in the traveling direction D0 are referred to as first photoconductors 41a, respectively, and the remaining one arranged sequentially from the most upstream side in the traveling direction D0. The photoconductor 41 is referred to as a second photoconductor 41b (see FIG. 4).

  Similarly, the three belt transfer rollers 441 facing the three first photoconductors 41a are referred to as a first belt transfer roller 441a, and the belt transfer roller 441 facing the second photoconductor 41b is a second belt transfer. This is referred to as a roller 441b (see FIG. 4).

  As shown in FIG. 3, the intermediate transfer belt 440 has an annular belt base 440a and an elastic layer 440b laminated on the outer peripheral surface of the belt base 440a. The elastic layer 440b is a member that is softer than the belt base 440a.

  The elastic layer 440 b is in contact with the four photoconductors 41. On the other hand, the belt base 440 a is in contact with the four belt transfer rollers 441.

  For example, it is conceivable that the belt base 440a is a member mainly composed of polyvinylidene fluoride and the elastic layer 440b is a member mainly composed of urethane rubber. In the example shown in FIG. 3, the elastic layer 440b includes a coating 440c formed on the outer peripheral surface thereof. For example, the coating 440c may be a film containing fluorine as a main component.

  The sheet supply mechanism 2 sends out the sheet stored in the sheet storage unit 20 to the conveyance path 30. The sheet transport mechanism 3 transports the sheet along the transport path 30.

  The four photoconductors 41 are rotationally driven by the drive mechanism together with the intermediate transfer belt 440. That is, the four photoconductors 41 are rotating bodies on which toner images of different colors are formed on the surfaces.

  The charging device 42 uniformly charges the surface of the photoconductor 41. The optical scanning device 46 writes an electrostatic latent image on the surface of the photoconductor 41 by scanning the surface of the photoconductor 41 with laser light.

  The developing device 43 develops the electrostatic latent image with the toner 90 by supplying the toner 90 to the surface of the photoreceptor 41. As a result, a toner image is formed on the surface of the photoreceptor 41.

  The four belt transfer rollers 441 are rotatably supported while being urged to the four photoreceptors 41 via the intermediate transfer belt 440, respectively. Each belt transfer roller 441 is urged toward the photoreceptor 41 by a spring (not shown).

  As shown in FIG. 2, each belt transfer roller 441 includes a cored bar 4411 and an elastic layer 4412 formed around the cored bar 4411. The elastic layer 4412 is, for example, a conductive foamed rubber member.

  When each belt transfer roller 441 is urged toward each photoreceptor 41, the elastic layer 4412 of each belt transfer roller 441 is elastically deformed into a shape along the outer peripheral surface of each photoreceptor 41. Thus, the four belt transfer rollers 441 form four nip portions with the four photoreceptors 41 via the intermediate transfer belt 440, respectively. In the present embodiment, the elastic layer 440b of the intermediate transfer belt 440 also contributes to the formation of the nip portion.

  As shown in FIG. 4, the four nip portions include three first nip portions N1 and one second nip portion N2. The three first belt transfer rollers 441a form three first nip portions N1 via the intermediate transfer belt 440 between the three first photoconductors 41a. Similarly, the second belt transfer roller 441b forms a second nip portion N2 via the intermediate transfer belt 440 with the second photoconductor 41b.

  A primary transfer voltage is applied to each of the four belt transfer rollers 441 by a primary transfer voltage application device (not shown). As a result, the four belt transfer rollers 441 transfer the toner images from the plurality of photosensitive members to the intermediate transfer belt 440.

  The belt transfer roller 441 transfers the toner image on the surface of the photoreceptor 41 to the intermediate transfer belt 440. As a result, a color toner image in which the four color toner images overlap is formed on the outer surface of the intermediate transfer belt 440. The drum cleaning device 45 removes the toner 90 remaining on the surface of the photoreceptor 41.

  The sheet transfer roller 442 has the same structure as the belt transfer roller 441. A secondary transfer voltage is applied to the sheet transfer roller 442 by a secondary transfer voltage application device (not shown). As a result, the sheet transfer roller 442 transfers the toner image on the intermediate transfer belt 440 to the sheet conveyed along the conveyance path 30.

  The primary transfer voltage and the secondary transfer voltage include at least a DC voltage component having a polarity opposite to the polarity of the charged toner 90. In some cases, the primary transfer voltage and the secondary transfer voltage include the DC voltage component and the AC voltage component.

  The fixing device 47 fixes the toner image on the sheet by heating the toner image transferred to the sheet. The belt cleaning device 443 removes the toner 90 remaining on the intermediate transfer belt 440.

  The four supply units 5 store toners 90 of different colors, and supply the toner 90 to the four developing devices 43, respectively.

  By the way, the a-Si photosensitive member has a dielectric constant larger than that of the organic photosensitive member. That is, in the a-Si photosensitive member, the charge amount of the electrostatic latent image is large. Therefore, each toner dot formed on the surface of the a-Si photosensitive member has a large thickness and a small area.

  Therefore, the toner image formed on the a-Si photoreceptor is a sharp image faithful to the electrostatic latent image. Further, when the a-Si photoreceptor is employed, the dot scattering due to the Paschen discharge is less likely to occur than when the organic photoreceptor is employed.

  On the other hand, in a portion where the toner dots of a plurality of colors on the intermediate transfer belt 440 overlap, a transfer defect of toner dots transferred later may occur. This transfer failure is particularly remarkable when the a-Si photosensitive member is employed. The toner dot transfer failure leads to deterioration of the color balance of the output image.

  The image forming apparatus 10 has a structure that can prevent transfer failure of the toner 90 in a portion where dots of a plurality of colors overlap. The structure will be described below.

  As shown in FIG. 4, the three first belt transfer rollers 441a are located at positions where the respective rotation centers are shifted to the upstream side in the traveling direction D0 with respect to the respective rotation centers of the three first photoconductors 41a. Has been placed.

  For example, the shift width dX1 of the first belt transfer roller 441a to the upstream side in the traveling direction D0 with respect to each first photoconductor 41a is in the range of 5 to 150% of the diameter of the first belt transfer roller 441a. Conceivable.

  On the other hand, the rotation center of the second belt transfer roller 441b is disposed at the same position in the traveling direction D0 with respect to the rotation center of the second photoconductor 41b. It is also conceivable that the second belt transfer roller 441b is disposed at a position where the rotation center is shifted to the downstream side in the traveling direction D0 with respect to the rotation center of the second photoconductor 41b.

  In the present embodiment, the three first belt transfer rollers 441a and the second belt transfer roller 441b are formed with the same outer diameter, and have elastic layers 4412 of the same thickness and the same material, respectively. The three first photoconductors 41a and the second photoconductor 41b are also members having the same outer diameter, the same thickness, and the same material.

  In FIG. 5, two descriptions of the three first nip portions N1 are omitted. In the following description, the width of the first nip portion N1 and the width of the second nip portion N2 mean the width in the traveling direction D0.

  In the following description, the upstream area and the downstream area in the traveling direction D0 from the rotation center of each of the three first photoconductors 41a in each of the three first nip portions N1 are respectively the areas before the first nip. N11 and first post-nip region N12 are referred to. Similarly, in the second nip portion N2, the upstream region and the downstream region in the traveling direction D0 from the rotation center of the second photoconductor 41b are respectively referred to as a second pre-nip region N21 and a second post-nip region N22. Called.

  As shown in FIG. 5, in each of the three first nip portions N1, the width of the first pre-nip region N11 is larger than the width of the first post-nip region N12. On the other hand, in the second nip portion N2, the width of the second pre-nip region N21 is equal to the width of the second post-nip region N22.

  On the other hand, the width of the first pre-nip region N11 in each of the three first nip portions N1 is larger than the width of the second pre-nip region N21 in the second nip portion N2 (see FIG. 5).

  In the image forming apparatus 10, the Paschen discharge on the upstream side in the traveling direction D0 is promoted in each of the three first nip portions N1. As a result, in each of the three first nip portions N1, the toner dots are transferred to the surface of the intermediate transfer belt 440 with a relatively small thickness and a relatively large area.

  Therefore, in a portion where the toner dots of a plurality of colors overlap on the intermediate transfer belt 440, a transfer defect of the toner dots transferred later hardly occurs.

  On the other hand, in the second nip portion N2, the Paschen discharge on the upstream side in the traveling direction D0 is suppressed. As a result, in the second nip portion N2, each toner dot is transferred to the surface of the intermediate transfer belt 440 with a relatively large thickness and a relatively small area.

  Accordingly, the three color toner images of yellow, cyan, and magenta are transferred to the intermediate transfer belt 440 with an appropriate color balance. On the other hand, the black toner image is transferred to the intermediate transfer belt 440 as a sharp image faithful to the electrostatic latent image.

  Further, as described above, in each first nip portion N1, the position of the first belt transfer roller 441a in the traveling direction D0 is deviated from the first photoconductor 41a. In this case, as shown in FIG. 5, the intermediate transfer belt 440 is deformed relatively greatly at the first nip portion N1.

  In the present embodiment, the intermediate transfer belt 440 has an elastic layer 440b that is softer than the belt base 440a. The elastic layer 440b is elastically deformed at the first nip portion N1. Thereby, the intermediate transfer belt 440 is not easily damaged due to the deformation at the first nip portion N1.

[First Reference Example]
Next, an image forming apparatus 10A according to a first reference example will be described with reference to FIGS. Also in the present embodiment, the intermediate transfer belt 440 includes an annular belt base 440a and an elastic layer 440b that is softer than the belt base 440a.

  6 and 7, the same components as those shown in FIGS. 1 to 5 are given the same reference numerals. Hereinafter, differences between the image forming apparatus 10A and the image forming apparatus 10 will be described.

  In the image forming apparatus 10A, the rotation centers of the four photosensitive members 41 and the four belt transfer rollers 441 are arranged in the same positional relationship in the traveling direction D0.

  In the example shown in FIGS. 6 and 7, the positions of the rotation centers of the four belt transfer rollers 441 are the same in the traveling direction D0 with respect to the rotation centers of the corresponding four photoreceptors 41, respectively.

  Therefore, as shown in FIG. 7, in each first nip portion N1, the width of the first pre-nip region N11 and the width of the first post-nip region N12 are the same. Similarly, also in the second nip portion N2, the width of the second pre-nip region N21 is equal to the width of the second post-nip region N22.

  In the present embodiment, the outer diameter of each of the four first belt transfer rollers 441a is larger than the outer diameter of the second belt transfer roller 441b. As a result, as shown in FIG. 7, the width of each of the three first nip portions N1 is larger than the width of the second nip portion N2.

  Accordingly, the width of the first pre-nip region N11 in each of the three first nip portions N1 is larger than the width of the second pre-nip region N21 in the second nip portion N2 (see FIG. 7). This point is common to the image forming apparatus 10 </ b> A and the image forming apparatus 10.

  That is, the image forming apparatus 10A is different from the image forming apparatus 10 in the structure for achieving the purpose of making the width of the first pre-nip region N11 larger than the width of the second pre-nip region N21.

  When the image forming apparatus 10A is employed, the same effect as that obtained when the image forming apparatus 10 is employed can be obtained.

  Furthermore, if the image forming apparatus 10A is employed, all of the four support mechanisms that support the four belt transfer rollers 441 can be made the same. As a result, the entire structure of the transfer device 44 can be simplified.

[Second Reference Example]
Next, an image forming apparatus 10B according to a second reference example will be described with reference to FIG. Also in the present embodiment, the intermediate transfer belt 440 includes an annular belt base 440a and an elastic layer 440b that is softer than the belt base 440a.

  In FIG. 8, the same components as those shown in FIGS. 1 to 7 are given the same reference numerals. Hereinafter, differences of the image forming apparatus 10B from the image forming apparatus 10A will be described.

  Also in the image forming apparatus 10B, the four photosensitive members 41 and the four belt transfer rollers 441 are arranged such that the rotation centers of the corresponding ones are the same in the traveling direction D0. This is the same as the image forming apparatus 10A.

  However, in the present embodiment, the positions of the rotation centers of the four belt transfer rollers 441 are positions downstream in the traveling direction D0 with respect to the rotation centers of the corresponding four photoreceptors 41, respectively.

  In this embodiment, the deviation width dX2 of the four first belt transfer rollers 441a to the downstream side in the traveling direction D0 with respect to each of the four photoconductors 41 is 10 to 20% of the diameter of the first belt transfer roller 441a. It is considered that it is within the range.

  Therefore, as shown in FIG. 8, in each first nip portion N1, the width of the first pre-nip region N11 is smaller than the width of the first post-nip region N12. Similarly, also in the second nip portion N2, the width of the second pre-nip region N21 is smaller than the width of the second post-nip region N22.

  In the present embodiment, the outer diameter of each of the four first belt transfer rollers 441a is larger than the outer diameter of the second belt transfer roller 441b. Accordingly, as shown in FIG. 8, the width of each of the three first nip portions N1 is larger than the width of the second nip portion N2.

  Accordingly, the width of the first pre-nip region N11 in each of the three first nip portions N1 is larger than the width of the second pre-nip region N21 in the second nip portion N2 (see FIG. 8). This point is common to the image forming apparatus 10B and the image forming apparatuses 10 and 10A.

  That is, the image forming apparatus 10B is different from the image forming apparatuses 10 and 10A in the structure for achieving the purpose of making the width of the first pre-nip region N11 larger than the width of the second pre-nip region N21. .

  When the image forming apparatus 10A is employed, the same effect as that obtained when the image forming apparatus 10 is employed can be obtained.

  Furthermore, if the image forming apparatus 10B is employed, all of the four support mechanisms that support the four belt transfer rollers 441 can be made the same. As a result, the entire structure of the transfer device 44 can be simplified.

  In general, when the organic photoconductor is employed as the photoconductor 41, each belt transfer roller 441 has its rotation center positioned on the downstream side in the traveling direction D0 with respect to the rotation center of each corresponding photoconductor 41. Be placed. Therefore, the four support mechanisms in the image forming apparatus 10B can be employed even when the four photoconductors 41 are replaced with the four organic photoconductors.

[First application example]
The image forming apparatus according to the first application example is different from the image forming apparatuses 10A and 10B in the following points. That is, in this application example, the outer diameter of each of the four first belt transfer rollers 441a is the same as the outer diameter of the second belt transfer roller 441b.

  However, in this application example, the elastic layer 4412 of each of the three first belt transfer rollers 441a is thicker than the elastic layer 4412 of the second belt transfer roller 441b. Therefore, when the four belt transfer rollers 441 are biased with the same force, the elastic layer 4412 of each of the first belt transfer rollers 441a is deformed more greatly than the elastic layer 4412 of the second belt transfer roller 441b.

  Therefore, also in this application example, the width of each of the three first nip portions N1 is larger than the width of the second nip portion N2. When this application example is adopted, the same effects as those obtained when the image forming apparatuses 10A and 10B are adopted can be obtained.

[Second application example]
The image forming apparatus according to the second application example is different from the image forming apparatuses 10A and 10B in the following points. That is, in this application example, the outer diameter of each of the four first belt transfer rollers 441a is the same as the outer diameter of the second belt transfer roller 441b.

  However, in this application example, the elastic layer 4412 of each of the three first belt transfer rollers 441a is made of a softer material than the elastic layer 4412 of the second belt transfer roller 441b. Therefore, when the four belt transfer rollers 441 are biased with the same force, the elastic layer 4412 of each of the first belt transfer rollers 441a is deformed more greatly than the elastic layer 4412 of the second belt transfer roller 441b.

  Therefore, also in this application example, the width of each of the three first nip portions N1 is larger than the width of the second nip portion N2. When this application example is adopted, the same effects as those obtained when the image forming apparatuses 10A and 10B are adopted can be obtained.

1: Main body 2: Sheet supply mechanism 3: Sheet transport mechanism 4: Image forming unit 5: Replenishment unit 10: Image forming apparatus 10A: Image forming apparatus 10B: Image forming apparatus 20: Sheet storage unit 30: Transport path 40: Image formation Unit 41: Photoconductor 41a: First photoconductor 41b: Second photoconductor 42: Charging device 43: Developing device 44: Transfer device 44a: Belt substrate 45: Drum cleaning device 46: Optical scanning device 47: Fixing device 90: Toner 440: Intermediate transfer belt 440a: Belt substrate 440b: Elastic layer 440c: Coating 441: Belt transfer roller 441a: First belt transfer roller 441b: Second belt transfer roller 442: Sheet transfer roller 443: Belt cleaning device 444: Stretching roller 4411: Core metal 4412: Elastic layer D0: Traveling direction 1: the first nip portion N11: the first pre-nip region N12: first nip after region N2: second nip N21: second pre-nip region N22: After the second nip region

Claims (3)

A rotating body on which toner images of different colors are formed on the surface, each having a photosensitive layer of amorphous silicon, and a plurality of photosensitive bodies arranged in parallel at intervals in a predetermined direction;
An annular intermediate transfer belt that is stretched over a plurality of supports and rotates while contacting the plurality of photoconductors;
Each of the plurality of photoconductors is rotatably supported while being biased to the plurality of photoconductors via the intermediate transfer belt, each has an elastic layer, and each of the plurality of photoconductors is applied with the transfer voltage by applying the transfer voltage. A plurality of belt transfer rollers for transferring the toner image to a transfer belt,
The plurality of photoconductors include a plurality of first photoconductors arranged in order from the most upstream side in the predetermined direction and a second photoconductor arranged on the most downstream side in the predetermined direction,
The plurality of belt transfer rollers include a plurality of first belt transfer rollers facing the plurality of first photoconductors and a second belt transfer roller facing the second photoconductors, respectively.
The plurality of first belt transfer rollers are arranged at positions where the respective rotation centers are shifted to the upstream side in the predetermined direction with respect to the respective rotation centers of the plurality of first photoconductors.
The image forming apparatus, wherein the rotation center of the second belt transfer roller is disposed at the same position in the predetermined direction with respect to the rotation center of the second photoconductor or a position shifted downstream in the predetermined direction.   2. The image forming apparatus according to claim 1, wherein each of the plurality of first belt transfer rollers and the second belt transfer roller is formed with the same outer diameter and has the elastic layer with the same thickness. The intermediate transfer belt has an annular belt base and an elastic layer laminated on the belt base and softer than the belt base,
The image forming apparatus according to claim 1, wherein the elastic layer is in contact with the plurality of photoconductors.

Images