Intermediate transfer device and image forming apparatus

Abstract

To provide an intermediate transfer device that is reduced in size and has a mechanism that brings primary transfer rollers into proximity to an intermediate transfer belt and separates the primary transfer rollers from the intermediate transfer belt.SOLUTION: An intermediate transfer device 40 comprises: an intermediate transfer belt 31; a plurality of primary transfer rollers 32r; a plurality of pairs of support members 42; urging members 43; a pair of moving members 44; and a pair of frame members 41. The plurality of pairs of support members 42 rotatably support both ends of rotation shafts 32x of the plurality of primary transfer rollers 32r and can oscillate in directions in which the primary transfer rollers 32r come into proximity to and separate from the intermediate transfer belt 31. The pair of moving members 44 are in contact with the support members 42 on both ends of the rotation shafts 32x of the plurality of primary transfer rollers 32r and oscillate the support members 42. The moving members 44 are arranged between the pair of frame members 41 in the direction of the axis of rotation of the primary transfer rollers 32r and inside the intermediate transfer belt 31.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an intermediate transfer device and an image forming apparatus that include an endless intermediate transfer belt. [Background technology]

[0002] In electrophotographic image forming apparatuses such as copying machines and printers, there is known an intermediate transfer type image forming apparatus that sequentially superimposes and transfers different color toner images formed on the outer peripheral surfaces of a plurality of photosensitive drums (image carriers) onto an endless intermediate transfer belt arranged along the plurality of photosensitive drums (image carriers), and then secondarily transfers the toner images onto paper. An example of such an image forming apparatus is disclosed in Patent Document 1.

[0003] The conventional image forming apparatus disclosed in Patent Document 1 includes an intermediate transfer belt supported by multiple support rollers, multiple photoconductor drums arranged in parallel so as to be in contact with and face the intermediate transfer belt, and a swinging mechanism that separates the intermediate transfer belt from some of the photoconductor drums so that they are positioned apart from each other. By separating the intermediate transfer belt from some of the photoconductor drums using the swinging mechanism, problems such as a shortened lifespan of the photoconductor drums and scattering and waste of developer due to unnecessary contact and proximity between the intermediate transfer belt and the photoconductor drums can be prevented. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-108788 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the case of the conventional technology, many of the components of the mechanism for separating the intermediate transfer belt from the photosensitive drum are located outside the intermediate transfer belt in the width direction perpendicular to the moving direction of the intermediate transfer belt, which may lead to an increase in the size of the image forming apparatus.

[0006] The present invention has been made in consideration of the above-mentioned points, and aims to provide an intermediate transfer device and an image forming apparatus that have a mechanism for moving a primary transfer roller toward and away from an intermediate transfer belt, and that are compact in size. [Means for solving the problem]

[0007] In order to solve the above problems, the intermediate transfer device of the present invention includes an intermediate transfer belt, a plurality of primary transfer rollers, a plurality of pairs of support members, a biasing member, a pair of moving members, and a pair of frame members. The intermediate transfer belt is endless and moves along the arrangement direction of the plurality of image carriers. The plurality of primary transfer rollers are arranged facing the plurality of image carriers with the intermediate transfer belt interposed therebetween, and transfer toner images formed on the outer circumferential surfaces of the plurality of image carriers onto the intermediate transfer belt in a sequentially overlapping manner. The plurality of pairs of support members rotatably support both ends of the rotation shafts of the plurality of primary transfer rollers, and are capable of swinging in a direction in which the primary transfer rollers approach and move away from the intermediate transfer belt. The biasing member biases the support member in a direction in which the primary transfer rollers approach the intermediate transfer belt. The pair of moving members contact the support member at both ends of the rotation shafts of the plurality of primary transfer rollers, and swing the support member. The pair of frame members are disposed at both ends of the rotation shafts of the primary transfer rollers and support the support member so as to be able to swing, and the moving member is disposed between the pair of frame members and on the inner side of the intermediate transfer belt in the direction of the rotation axis of the primary transfer rollers. Effect of the Invention

[0008] According to the configuration of the present invention, the moving member that rocks the support member of the primary transfer roller is not located outside the intermediate transfer belt in the width direction of the intermediate transfer belt. In other words, some of the components of the mechanism that moves the primary transfer roller toward and away from the intermediate transfer belt can be accommodated inside the intermediate transfer belt. Therefore, it is possible to reduce the size of the intermediate transfer device and the image forming device. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic sectional front view illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. [Diagram 2] 2 is a cross-sectional front view showing an intermediate transfer device of the image forming apparatus of FIG. 1. [Diagram 3] 3 is a partial cross-sectional front view showing the periphery of a support member for a primary transfer roller of the intermediate transfer device of FIG. 2. [Figure 4] 4 is a partial cross-sectional side view showing the periphery of a support member for a primary transfer roller of the intermediate transfer device of FIG. 3. [Diagram 5] 4 is a perspective view showing a supporting member and a moving member of the primary transfer roller of the intermediate transfer device of FIG. 3. [Figure 6] 3 is a partial cross-sectional front view showing the periphery of a support member for a primary transfer roller of the intermediate transfer device in FIG. 2, and shows a state in which a moving member has been moved. FIG. [Figure 7] 7 is a perspective view showing a supporting member and a moving member of the primary transfer roller of the intermediate transfer device of FIG. 6. [Figure 8] 3 is a partial cross-sectional front view showing the vicinity of a contact / separation mechanism for a secondary transfer roller of the intermediate transfer device of FIG. 2. [Figure 9] 9 is a rear view showing a contact / separation mechanism for a secondary transfer roller of the intermediate transfer device in FIG. 8 and the periphery of the secondary transfer roller. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following.

[0011] Fig. 1 is a schematic cross-sectional front view showing the configuration of an image forming apparatus 1 of an embodiment. Fig. 2 is a cross-sectional front view showing an intermediate transfer device 40 of the image forming apparatus 1 of Fig. 1. One example of the image forming apparatus 1 of this embodiment is a tandem color printer that transfers a toner image onto paper S using an intermediate transfer belt 31. The image forming apparatus 1 may be a so-called multifunction machine equipped with functions such as printing, scanning (image reading), and facsimile transmission.

[0012] As shown in Figures 1 and 2, the image forming apparatus 1 includes a paper feed section 3, a paper transport section 4, an exposure section 5, an image forming section 20, a transfer section 30, a fixing section 6, a paper discharge section 7, and a control section 8, which are provided in a main body 2.

[0013] The paper feed section 3 stores a plurality of sheets of paper S, and separates and sends out the sheets (recording media) S one by one during printing. The paper transport section 4 transports the paper S sent out from the paper feed section 3 to the secondary transfer section 33 and the fixing section 6, and further discharges the paper S after fixing from the paper discharge port 4a to the paper discharge section 7. When double-sided printing is performed, the paper transport section 4 distributes the paper S after fixing of the first side to the reversal transport section 4c by the branch section 4b, and transports the paper S again to the secondary transfer section 33 and the fixing section 6. The exposure section 5 irradiates the image forming section 20 with laser light controlled based on image data.

[0014] The image forming units 20 are disposed below the intermediate transfer belt 31. The image forming units 20 include an image forming unit 20Y for yellow, an image forming unit 20M for magenta, an image forming unit 20C for cyan, and an image forming unit 20B for black. These four image forming units 20 have the same basic configuration. Therefore, in the following description, the identification symbols "Y", "M", "C", and "B" representing each color may be omitted unless there is a particular need to limit it.

[0015] As shown in Fig. 2, the image forming unit 20 includes a photoconductor drum (image carrier) 21 that is supported so as to be rotatable in a predetermined direction (clockwise in Fig. 1). The photoconductor drum 21 is disposed with its rotation axis horizontal. The image forming unit 20 further includes a charging unit, a developing unit, and a drum cleaning unit that are disposed around the photoconductor drum 21 along its rotation direction. A primary transfer unit 32 is disposed between the developing unit and the drum cleaning unit.

[0016] The photoreceptor drum 21 has a photosensitive layer on its outer circumferential surface. The charging section charges the outer circumferential surface of the photoreceptor drum 21 to a predetermined potential. The exposure section 5 exposes the outer circumferential surface of the photoreceptor drum 21 charged by the charging section, and forms an electrostatic latent image of the original image on the outer circumferential surface of the photoreceptor drum 21. The developing section develops the electrostatic latent image by attaching toner to the electrostatic latent image, forming a toner image. Each of the four image forming sections 20 forms a toner image of a different color. The drum cleaning section removes toner and the like remaining on the outer circumferential surface of the photoreceptor drum 21 after the toner image is primarily transferred to the outer circumferential surface of the intermediate transfer belt 31, cleaning the photoreceptor drum 21.

[0017] 1, the transfer unit 30 includes an intermediate transfer belt 31, primary transfer units 32Y, 32M, 32C, and 32B, a secondary transfer unit 33, and a belt cleaning unit 34. The intermediate transfer belt 31 is disposed above the four image forming units 20. The intermediate transfer belt 31 is supported so as to be rotatable in a predetermined direction (counterclockwise in FIG. 1), and serves as an intermediate transfer body onto which the toner images formed in each of the four image forming units 20 are sequentially superimposed and primarily transferred. The four image forming units 20 are disposed in a so-called tandem manner, lined up in a row from the upstream side to the downstream side in the rotation direction of the intermediate transfer belt 31.

[0018] The primary transfer units 32Y, 32M, 32C, and 32B are disposed above the image forming units 20Y, 20M, 20C, and 20B of the respective colors, with the intermediate transfer belt 31 sandwiched therebetween. The secondary transfer unit 33 is disposed upstream of the fixing unit 6 in the paper conveying direction of the paper conveying unit 4, and downstream of the image forming units 20Y, 20M, 20C, and 20B of the respective colors in the rotation direction of the intermediate transfer belt 31 of the transfer unit 30. The belt cleaning unit 34 is disposed, for example, upstream of the image forming units 20Y, 20M, 20C, and 20B of the respective colors in the rotation direction of the intermediate transfer belt 31.

[0019] The toner images are primarily transferred at primary transfer units 32Y, 32M, 32C, and 32B of each color onto the outer circumferential surface of the intermediate transfer belt 31. Then, as the intermediate transfer belt 31 rotates, the toner images of the four image forming units 20 are successively superimposed and transferred onto the intermediate transfer belt 31 at a predetermined timing, so that a color toner image is formed on the outer circumferential surface of the intermediate transfer belt 31 in which the toner images of the four colors, yellow, cyan, magenta, and black, are superimposed.

[0020] The color toner image on the outer peripheral surface of the intermediate transfer belt 31 is transferred at a secondary transfer nip portion formed in the secondary transfer portion 33 onto the paper S, which is synchronously fed by the paper transport portion 4. The belt cleaning portion 34 removes and cleans the toner and the like remaining on the outer peripheral surface of the intermediate transfer belt 31 after the secondary transfer.

[0021] The fixing unit 6 is disposed downstream of the secondary transfer unit 33 in the paper transport direction of the paper transport unit 4, and above the secondary transfer unit 33. The fixing unit 6 heats and pressurizes the paper S onto which the toner image has been transferred, thereby fixing the toner image to the paper S.

[0022] The paper discharge section 7 is disposed above the transfer section 30. The paper S on which the toner image has been fixed and printing has been completed is transported to the paper discharge section 7.

[0023] The control unit 8 includes a CPU, an image processing unit, a storage unit, and other electronic circuits and electronic components (all not shown). The CPU controls the operation of each component provided in the image forming apparatus 1 based on control programs and data stored in the storage unit to perform processing related to the functions of the image forming apparatus 1. The paper feed unit 3, the paper transport unit 4, the exposure unit 5, the image forming unit 20, the transfer unit 30, and the fixing unit 6 each receive individual commands from the control unit 8 and print on the paper S in cooperation with each other. The storage unit is configured by a combination of a non-volatile storage device such as a program ROM (Read Only Memory) or a data ROM, and a volatile storage device such as a RAM (Random Access Memory).

[0024] Next, the configuration of the transfer unit 30 will be described in detail. The transfer unit 30 includes an intermediate transfer device 40 shown in Figs. 1 and 2. Fig. 2 is a cross-sectional front view showing the intermediate transfer device 40 of the image forming apparatus 1 of Fig. 1. In this embodiment, the width direction perpendicular to the moving direction of the intermediate transfer belt 31 extends parallel to the front-rear direction of the image forming apparatus 1 (the depth direction of the paper in Figs. 1 and 2). Fig. 2 is a cross-sectional front view of the intermediate transfer device 40 seen from the middle part in the width direction of the intermediate transfer belt 31 to the rear side.

[0025] The intermediate transfer device 40 includes a pair of frame members 41, an intermediate transfer belt 31, a plurality of support rollers, and four primary transfer rollers 32r.

[0026] The pair of frame members 41 are disposed on the front and rear side surfaces of the intermediate transfer device 40. The pair of frame members 41 extend in the vertical direction and along the moving direction of the intermediate transfer belt 31. The pair of frame members 41 rotatably support the multiple mounting rollers and the four primary transfer rollers 32r.

[0027] The intermediate transfer belt 31 is disposed along the four image forming units 20. The intermediate transfer belt 31 is endless and rotatably supported by a plurality of mounting rollers. The intermediate transfer belt 31 moves along the arrangement direction of the four photoconductor drums 21.

[0028] In this embodiment, the multiple installation rollers include a drive roller 35 and a driven roller 36 .

[0029] The drive roller 35 is disposed downstream of the image forming units 20Y, 20M, 20C, and 20B of each color in the rotation direction of the intermediate transfer belt 31. The drive roller 35 receives power from a drive motor (not shown) and rotates the intermediate transfer belt 31 counterclockwise in FIG.

[0030] The drive roller 35 is disposed adjacent to the secondary transfer unit 33. A secondary transfer roller 33r is disposed in the secondary transfer unit 33. The secondary transfer roller 33r is disposed at a position facing the drive roller 35 with the intermediate transfer belt 31 therebetween, and is in contact with the outer circumferential surface of the intermediate transfer belt 31.

[0031] The driven roller 36 is disposed upstream of the image forming units 20Y, 20M, 20C, and 20B of each color in the rotation direction of the intermediate transfer belt 31. The driven roller 36 rotates counterclockwise in FIG. 2 in accordance with the rotation of the intermediate transfer belt 31. The driven roller 36 is biased by a spring (not shown) in a direction away from the drive roller 35. This provides a predetermined tension to the intermediate transfer belt 31.

[0032] The four primary transfer rollers 32r are disposed above the four image forming units 20, respectively, with the intermediate transfer belt 31 between them. Each primary transfer roller 32r is disposed facing the photoconductor drum 21 with the intermediate transfer belt 31 in between, and contacts the inner circumferential surface of the intermediate transfer belt 31. Each primary transfer roller 32r transfers the toner images formed on the outer circumferential surfaces of the four photoconductor drums 21, respectively, onto the intermediate transfer belt 31 in sequence.

[0033] Next, a detailed configuration of the intermediate transfer device 40 will be described. FIG. 3 is a partial cross-sectional front view showing the periphery of the support member of the primary transfer roller 32r of the intermediate transfer device 40 in FIG. 2. FIG. 4 is a partial cross-sectional side view showing the periphery of the support member of the primary transfer roller 32r of the intermediate transfer device 40 in FIG. 3. FIG. 5 is a perspective view showing the support member and moving member of the primary transfer roller 32r of the intermediate transfer device 40 in FIG. 3. FIG. 6 is a partial cross-sectional front view showing the periphery of the support member of the primary transfer roller 32r of the intermediate transfer device 40 in FIG. 2, showing a state in which the moving member has been moved. FIG. 7 is a perspective view showing the support member and moving member of the primary transfer roller 32r of the intermediate transfer device 40 in FIG. 6.

[0034] The intermediate transfer device 40 includes a support member 42, an urging member 43, a pair of moving members 44, and a drive gear 45. The support member 42, the urging member 43, the moving member 44, and the drive gear 45 are attached to a pair of frame members 41 arranged on the front and rear side surfaces of the intermediate transfer device 40, respectively.

[0035] The support member 42 is attached to the lower part of the frame member 41. The support member 42 extends in the moving direction of the intermediate transfer belt 31, i.e., in a direction intersecting with the rotation axis of the primary transfer roller 32r. The support member 42 includes a support portion 421, a contacted portion 422, and a swing shaft portion 423, which are arranged along the longitudinal direction (extension direction).

[0036] The support portion 421 is provided on one end side of the support member 42 in the longitudinal direction. In other words, in this embodiment, the support portion 421 is provided at the end portion on the downstream side in the moving direction of the intermediate transfer belt 31 at the location facing the primary transfer roller 32r. The support portion 421 supports the primary transfer roller 32r. In detail, the support portion 421 has bearings 421b that rotatably support both ends of the rotation shaft 32x of the primary transfer roller 32r. When the toner image is primarily transferred to the intermediate transfer belt 31, the support portion 421 is located at a position where the primary transfer roller 32r contacts the inner circumferential surface of the intermediate transfer belt 31.

[0037] The contacted portion 422 is provided on the other end side in the longitudinal direction of the support member 42. In other words, in this embodiment, the contacted portion 422 is provided at the end on the upstream side in the moving direction of the intermediate transfer belt 31 at the location facing the primary transfer roller 32r. The contacted portion 422 comes into contact with the moving member 44. When the toner image is primarily transferred onto the intermediate transfer belt 31, the contacted portion 422 is located above the support portion 421 and on the moving path of a contact piece 441 of the moving member 44, which will be described later.

[0038] The swing shaft portion 423 is provided between the support portion 421 and the contacted portion 422 in the longitudinal direction of the support member 42. The swing shaft portion 423 extends along the axial direction of the primary transfer roller 32r. The support member 42 is swingably supported by the frame member 41 via the swing shaft portion 423. When the support member 42 swings about the swing shaft portion 423, the support portion 421 and the contacted portion 422 move in the vertical direction.

[0039] That is, the support member 42 can swing in a direction in which the primary transfer rollers 32r approach and move away from the intermediate transfer belt 31. That is, the pair of frame members 41 are disposed at both ends of the rotation shafts 32x of the four primary transfer rollers 32r, and support the support member 42 so that it can swing.

[0040] The urging member 43 is disposed above the support portion 421. An upper end of the urging member 43 contacts the frame member 41, and a lower end of the urging member 43 contacts an upper side of the bearing 421b of the support portion 421. The urging member 43 is formed of, for example, a compression coil spring, and urges the support portion 421 of the support member 42 downward. That is, the urging member 43 urges the support member 42 in a direction in which the primary transfer roller 32r approaches the intermediate transfer belt 31.

[0041] The moving member 44 is attached to the upper part of the frame member 41. The moving member 44 extends along the moving direction of the intermediate transfer belt 31. The moving member 44 is formed in a long and thin rod shape extending from the vicinity of the secondary transfer unit 33 to the upper side of the primary transfer unit 32Y for yellow, which is the farthest from the secondary transfer unit 33.

[0042] The frame member 41 includes a moving member accommodating portion 411 that supports the moving member 44. The moving member 44 is supported by the frame member 41 so as to be capable of reciprocating movement along the movement direction of the intermediate transfer belt 31.

[0043] The moving member 44 includes a contact piece 441. The contact piece 441 protrudes in the direction of the rotation axis of the primary transfer roller 32r from a main body 44a of the moving member 44 extending along the moving direction of the intermediate transfer belt 31 (the rear side in the depth direction of the paper in FIG. 3, and the left side in the lateral direction in FIG. 4). The contact piece 441 is located on the moving path of the contacted portion 422 of the support member 42.

[0044] When the primary transfer roller 32r is at the primary transfer position where it contacts the inner circumferential surface of the intermediate transfer belt 31, if the moving member 44 moves along the movement direction of the intermediate transfer belt 31, the contact piece 441 comes into contact with the contacted portion 422 of the support member 42. As a result, as shown in FIGS. 6 and 7, the support member 42 is swung about the swing shaft portion 423 against the urging force of the urging member 43. The primary transfer roller 32r is separated from the inner circumferential surface of the intermediate transfer belt 31. In this manner, the moving member 44 swung the support member 42.

[0045] 4, the moving member 44 is disposed between the pair of frame members 41 in the direction of the rotation axis of the primary transfer roller 32r and inside the intermediate transfer belt 31. With this configuration, the moving member 44 is not positioned outside the intermediate transfer belt 31 in the width direction of the intermediate transfer belt 31. That is, some of the components of the mechanism that moves the primary transfer roller 32r toward and away from the intermediate transfer belt 31 can be accommodated inside the intermediate transfer belt 31. Therefore, it is possible to reduce the size of the intermediate transfer device 40 and the image forming apparatus 1.

[0046] The drive gear 45 is disposed below the moving member 44, for example, between the two primary transfer rollers 32r in the moving direction of the intermediate transfer belt 31. The drive gear 45 is rotatable about a rotation axis extending parallel to the rotation axis of the primary transfer roller 32r. The moving member 44 includes a drive rack 442. The drive rack 442 has a plurality of teeth juxtaposed in the moving direction of the intermediate transfer belt 31, and the drive gear 45 meshes with the drive rack 442.

[0047] The drive gear 45 is rotated in both forward and reverse directions by receiving power from a drive source (not shown) of the intermediate transfer device 40. By the drive gear 45 rotating in both forward and reverse directions, the moving member 44 can move back and forth along the moving direction of the intermediate transfer belt 31.

[0048] By reciprocating the moving member 44 along the moving direction of the intermediate transfer belt 31, the contact piece 441 comes into contact with and separates from the contacted portion 422 of the support member 42. The intermediate transfer device 40 oscillates the support member 42 between a separation position where the contact piece 441 comes into contact with the contacted portion 422 and the primary transfer roller 32r separates from the intermediate transfer belt 31 against the biasing force of the biasing member 43, and a contact position where the contact piece 441 separates from the contacted portion 422 and the primary transfer roller 32r comes into contact with the intermediate transfer belt 31 due to the biasing force of the biasing member 43. With this configuration, the moving member 44 housed inside the intermediate transfer belt 31 can easily move the primary transfer roller 32r toward and away from the intermediate transfer belt 31.

[0049] 2, the intermediate transfer device 40 includes a contact / separation mechanism 50 for the secondary transfer roller 33r. The contact / separation mechanism 50 is provided adjacent to the secondary transfer roller 33r that transfers the toner image on the intermediate transfer belt 31 onto the paper S.

[0050] Fig. 8 is a partial cross-sectional front view showing the periphery of the contact / separation mechanism 50 of the secondary transfer roller 33r of the intermediate transfer device 40 in Fig. 2. Fig. 9 is a rear view showing the periphery of the contact / separation mechanism 50 of the secondary transfer roller 33r and the secondary transfer roller 33r of the intermediate transfer device 40 in Fig. 8.

[0051] The moving member 44 includes a contact / separation rack 443. The contact / separation rack 443 is provided at an end of the moving member 44 on the secondary transfer unit 33 side. The contact / separation rack 443 has a plurality of teeth arranged in the moving direction of the intermediate transfer belt 31, and meshes with a contact / separation gear 51 described later.

[0052] The contact / separation mechanism 50 includes a contact / separation gear 51 and a contact / separation member 52 .

[0053] The contact / separation gear 51 is disposed below the moving member 44 and adjacent to the drive roller 35. The contact / separation gear 51 is rotatable about a rotation axis extending parallel to the rotation axis of the secondary transfer roller 33r. The contact / separation gear 51 meshes with the contact / separation rack 443 of the moving member 44. The contact / separation gear 51 is rotatable in both forward and reverse directions as the moving member 44 reciprocates along the moving direction of the intermediate transfer belt 31.

[0054] 9, the contact / separation member 52 is a cam member that is rotatable about a rotation axis that extends parallel to the rotation axis of the secondary transfer roller 33r. The contact / separation member 52 is connected to the contact / separation gear 51 and rotates together with the rotation of the contact / separation gear 51. A contact / separation mechanism contact portion 622 of an arm 62 of a swing mechanism 60 of the secondary transfer roller 33r, which will be described later, comes into contact with the periphery of the contact / separation member 52.

[0055] The image forming apparatus 1 includes a swing mechanism 60 for the secondary transfer roller 33r. The swing mechanism 60 includes a holder 61 and an arm 62.

[0056] The holder 61 rotatably supports both ends of the rotation shaft 33x of the secondary transfer roller 33r. The holder 61 is movable in a direction in which the secondary transfer roller 33r comes into contact with and separates from the intermediate transfer belt 31. The holder 61 is biased by a biasing member (not shown) in a direction in which the secondary transfer roller 33r approaches the intermediate transfer belt 31. The holder 61 has a contact portion 611. The arm 62 comes into contact with the contact portion 611 from a direction opposite to the biasing direction of the biasing member (not shown).

[0057] The arm 62 is disposed adjacent to the holder 61 and the contact / separation mechanism 50. The arm 62 extends substantially in the vertical direction. The arm 62 has a rotation shaft portion 62x at its lower end. The arm 62 is rotatably supported by the main body 2 via the rotation shaft portion 62x that extends parallel to the rotation shaft 33x of the secondary transfer roller 33r. The arm 62 has a holder contact portion 621 and a contact / separation mechanism contact portion 622 above the rotation shaft portion 62x.

[0058] The holder contact portion 621 is disposed between the contact / separation mechanism contact portion 622 and the rotating shaft portion 62x in the up-down direction of the arm 62. The holder contact portion 621 comes into contact with the contact portion 611 of the holder contact portion 621 from a direction opposite to the biasing direction of the holder 61 by the biasing member (not shown) of the holder 61.

[0059] The contact / separation mechanism contact portion 622 is disposed at the upper end portion of the arm 62. The contact / separation mechanism contact portion 622 protrudes toward the contact / separation mechanism 50. The contact / separation mechanism contact portion 622 comes into contact with the periphery of the contact / separation member 52 of the contact / separation mechanism 50.

[0060] For example, when the contact-separation member 52 of the contact-separation mechanism 50 rotates in the forward direction, the arm 62 in contact with the contact-separation member 52 swings in a direction in which the secondary transfer roller 33r moves away from the intermediate transfer belt 31 against the biasing force of the biasing member (not shown) of the holder 61. Also, for example, when the contact-separation member 52 of the contact-separation mechanism 50 rotates in the reverse direction, the arm 62 in contact with the contact-separation member 52 swings in a direction in which the secondary transfer roller 33r moves closer to the intermediate transfer belt 31 due to the biasing force of the biasing member (not shown) of the holder 61.

[0061] As described above, the contact / separation mechanism 50 has the contact / separation member 52 that moves the secondary transfer roller 33r in a direction toward and away from the intermediate transfer belt 31. The moving member 44 comes into contact with the contact / separation mechanism 50 and drives the contact / separation member 52. With this configuration, some of the components of the mechanism that moves the secondary transfer roller 33r toward and away from the intermediate transfer belt 31 can be accommodated inside the intermediate transfer belt 31. Therefore, it is possible to reduce the size of the intermediate transfer device 40 and the image forming apparatus 1.

[0062] In addition, by providing a contact / separation rack 443 provided on the moving member 44 and a contact / separation gear 51 and a contact / separation member 52 provided on the contact / separation mechanism 50, the secondary transfer roller 33r can be easily moved toward and away from the intermediate transfer belt 31 by the moving member 44 housed inside the intermediate transfer belt 31.

[0063] Although an embodiment of the present invention has been described above, the scope of the present invention is not limited to this, and various modifications can be made without departing from the spirit of the invention. [Industrial Applicability]

[0064] The present invention can be used in an intermediate transfer device and an image forming apparatus that include an endless intermediate transfer belt. [Explanation of symbols]

[0065] 1. Image forming device 20 Image forming section 21 Photoconductor drum (image carrier) 30 Transcription section 31 Intermediate transfer belt 32 Primary transfer section 32r Primary transfer roller 32x rotation axis 33 Secondary transfer section 33r Secondary transfer roller 33x rotation axis 40 Intermediate transfer device 41 Frame members 42 Support member 43 Pressing member 44 Moving parts 45 Drive gear 50 Approach / separation mechanism 51 Gear 52 Contact and separation member 421 Support part 422 Contacted part 423 Swing shaft 441 Contact piece 442 Drive rack 443 Attachment / detachment rack S Paper (recording medium)

Claims

1. An endless intermediate transfer belt that moves along the arrangement direction of the multiple image carriers; a plurality of primary transfer rollers disposed opposite the plurality of image carriers with the intermediate transfer belt interposed therebetween, and configured to sequentially transfer toner images formed on the outer peripheral surfaces of the plurality of image carriers onto the intermediate transfer belt in a superimposed manner; a plurality of pairs of support members that rotatably support both ends of a rotation shaft of the plurality of primary transfer rollers and are capable of swinging the primary transfer rollers in a direction in which the primary transfer rollers approach and move away from the intermediate transfer belt; a biasing member that biases the support member in a direction in which the primary transfer roller approaches the intermediate transfer belt; a pair of moving members that contact the support member at both ends of the rotation shafts of the plurality of primary transfer rollers and swing the support member; a pair of frame members disposed at both ends of the rotation shafts of the plurality of primary transfer rollers and supporting the support member in a swingable manner; a contact / separation mechanism provided adjacent to a secondary transfer roller that transfers the toner image on the intermediate transfer belt onto a recording medium, the contact / separation mechanism having a contact / separation member that moves the secondary transfer roller in a direction toward and away from the intermediate transfer belt; Equipped with the moving member is disposed between the pair of frame members and on the inner side of the intermediate transfer belt in the direction of the rotation axis of the primary transfer roller, and is in contact with the contact-separation mechanism to drive the contact-separation member, and includes a contact-separation rack adjacent to the contact-separation mechanism and having a plurality of teeth juxtaposed in the moving direction of the intermediate transfer belt; The contact / separation mechanism includes: a separation gear that meshes with the separation rack; a separation member that is disposed outside the pair of frame members in a rotation axis direction of the primary transfer roller, is connected to the separation gear, and rotates together with the separation gear to move the secondary transfer roller toward and away from the intermediate transfer belt; An intermediate transfer device comprising:

2. The support member extends in a direction intersecting with a rotation axis of the primary transfer roller, a support portion provided at one end side in a longitudinal direction and supporting the primary transfer roller; a contacted portion provided at the other end in the longitudinal direction and contacted by the moving member; a swing shaft portion provided between the support portion and the contacted portion in the longitudinal direction and swingably supported by the frame member; Equipped with the moving member includes a contact piece extending in a moving direction of the intermediate transfer belt and protruding in a direction of a rotation axis of the primary transfer roller, 2. The intermediate transfer device according to claim 1, wherein the movable member is reciprocated along the movement direction of the intermediate transfer belt, so that the support member is oscillated between a separation position where the contact piece contacts the contacted portion and the primary transfer roller separates from the intermediate transfer belt against the biasing force of the biasing member, and a contact position where the contact piece separates from the contacted portion and the primary transfer roller contacts the intermediate transfer belt due to the biasing force of the biasing member.

3. An image forming apparatus comprising an intermediate transfer device as described in claim 1 or claim 2.

Images