Transfer device and image forming apparatus

Abstract

To suppress load fluctuations of a transfer member compared to a configuration where an axis of a transfer roll and an end of a transfer jacket are parallel.SOLUTION: The transfer device comprises: a transfer member formed into an endless belt shape onto which a toner image is transferred; a transfer drum including a drum body with a recess extending in an axial direction formed on its outer peripheral surface, and a transfer jacket wound around the outer peripheral surface in a manner where both ends are positioned outside the recess; and a transfer roll extending in the axial direction, transferring the toner image to a recording medium wound around the transfer drum while sandwiching the transfer member with the transfer jacket, and repeating collision with and separation from the transfer jacket as it passes through the recess. At least one of both ends of the transfer jacket has an edge that is non-parallel to an axis of the transfer roll.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a transfer device and an image forming apparatus. [Background technology]

[0002] Patent Document 1 discloses an image forming apparatus including a transfer cylinder, in which a tapered surface is provided on the transfer cylinder. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-59720 A Summary of the Invention [Problem to be solved by the invention]

[0004] In an image forming apparatus equipped with a transfer device, in a configuration in which the transfer roll repeatedly collides with and separates from the transfer jacket of the transfer cylinder as the transfer roll passes through a recess in the transfer cylinder, when the transfer roll collides with or separates from the transfer jacket, a load fluctuation occurs in the transfer member sandwiched between the transfer roll and the transfer jacket.

[0005] An object of the present disclosure is to suppress load fluctuations on the transfer member compared to a configuration in which both ends of the transfer jacket are parallel to the axis of the transfer roll. [Means for solving the problem]

[0006] A transfer device according to a first aspect of the present disclosure comprises a transfer cylinder having a transfer member formed in an endless band and onto which a toner image is transferred, a cylinder main body having an axially extending recess formed on its outer peripheral surface, and a transfer jacket wrapped around the outer peripheral surface with both ends positioned outside the recess, and a transfer roll extending in the axial direction and transferring a toner image to a recording medium wrapped around the transfer cylinder while sandwiching the transfer member between the transfer jacket and the transfer roll, the transfer roll repeatedly colliding with and separating from the transfer jacket as it passes through the recess, and at least one of the both ends of the transfer jacket has an edge that is non-parallel to the axis of the transfer roll.

[0007] A transfer device according to a second aspect of the present disclosure is the transfer device according to the first aspect, wherein the transfer jacket is formed symmetrically with respect to a center in the axial direction.

[0008] A transfer device according to a third aspect of the present disclosure is the transfer device described in the second aspect, wherein the one end of the transfer jacket extends from both axial ends toward the center and toward the recess, forming a triangular shape.

[0009] A transfer device according to a fourth aspect of the present disclosure is the transfer device according to the first aspect, wherein both end portions of the transfer jacket have edges that are not parallel to the axis of the transfer roll.

[0010] A transfer device according to a fifth aspect of the present disclosure is the transfer device according to the fourth aspect, wherein both ends of the transfer jacket have different shapes.

[0011] A transfer device according to a sixth aspect of the present disclosure is the transfer device according to the first aspect, wherein the transfer jacket is replaceably attached to the trunk main body.

[0012] A transfer device according to a seventh aspect of the present disclosure is the transfer device described in the first aspect, which is provided with a covering portion that covers the portion between at least one of both end portions of the transfer jacket and the recess, and has a lower elastic modulus than the one end portion of the transfer jacket.

[0013] An image forming apparatus according to an eighth aspect of the present disclosure includes an image forming unit having an image forming unit that forms the toner image and a transfer device described in any one of the first to seventh aspects, and a fixing device that fixes the image transferred to a recording medium by the image forming unit. Effect of the Invention

[0014] According to the transfer device according to the first aspect of the present disclosure, load fluctuations on the transfer member are suppressed compared to a configuration in which both ends of the transfer jacket are parallel to the axis of the transfer roll.

[0015] According to the transfer device according to the second aspect of the present disclosure, axial skewing of the transfer member caused by rotation of the transfer cylinder is suppressed, compared to a configuration in which the transfer jacket is asymmetric.

[0016] According to the transfer device according to the third aspect of the present disclosure, processing of one end of the transfer jacket is simplified compared to a configuration in which one end extends toward a plurality of points.

[0017] According to the transfer device of the fourth aspect of the present disclosure, load fluctuations on the transfer member are suppressed both when the transfer roll collides with and separates from the transfer jacket, compared to a configuration in which only one end is non-parallel to the axis of the transfer roll.

[0018] According to the transfer device according to the fifth aspect of the present disclosure, load fluctuations are suppressed according to the shape of each end, compared to a configuration in which both end portions of the transfer jacket have the same shape.

[0019] According to the transfer device according to the sixth aspect of the present disclosure, it is easier to change the specifications of the end portion of the transfer jacket compared to when the transfer jacket is fixed to the barrel main body.

[0020] According to the transfer device according to the seventh aspect of the present disclosure, deterioration of the end portion facing the circumferential direction of the transfer jacket is suppressed, compared to a configuration in which the end surface is exposed.

[0021] According to the image forming device according to the eighth aspect of the present disclosure, disturbance of the image formed on the recording medium caused by repeated collision with and separation from the transfer jacket as the transfer roll passes through the recess is suppressed. [Brief description of the drawings]

[0022] [Figure 1] 1 is a schematic diagram illustrating an image forming apparatus according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a perspective view showing a configuration around a transfer cylinder according to an embodiment of the present disclosure. [Diagram 3] FIG. 1 illustrates a perspective view of a gripper according to an embodiment of the present disclosure. [Figure 4] FIG. 2 is a schematic diagram showing a positional relationship between a transfer cylinder and a secondary transfer roll according to an embodiment of the present disclosure. [Diagram 5] 11 is a schematic diagram illustrating a state in which a secondary transfer roll rides up on an upstream end of a recessed portion of a transfer cylinder according to an embodiment of the present disclosure. FIG. [Figure 6] 11 is a schematic diagram showing a state in which a transfer roll comes out from a downstream end of a recessed portion of a transfer cylinder according to an embodiment of the present disclosure. FIG. [Figure 7] FIG. 11 is a perspective view showing a configuration around a transfer cylinder according to another embodiment of the present disclosure. [Figure 8] (a) is a top view schematic diagram showing a first example of the upstream end periphery of a transfer jacket according to an embodiment of the present disclosure, (b) is a second example, (c) is a third example, and (d) is a fourth example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

[0024] <Image forming apparatus 10> The configuration of an image forming apparatus 10 according to an embodiment of the present disclosure (hereinafter referred to as "the present embodiment") will be described. FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus 10 according to the present embodiment. For convenience, arrow H shown in each figure indicates the vertical direction, which is the up-down direction of the apparatus, arrow W indicates the horizontal direction, which is the width direction of the apparatus, and arrow D indicates the horizontal direction, which is the depth direction of the apparatus (front-rear direction of the apparatus). The depth direction of the apparatus is an example of the axial direction. The dimensional ratios of the parts shown in each figure in the H direction, W direction, and D direction may differ from the actual dimensional ratios.

[0025] 1 is an image forming apparatus that forms a toner image (one example of an image) on a recording medium P. Specifically, the image forming apparatus 10 includes an image forming section 12, a fixing device 15, and a conveying mechanism 16. Each section of the image forming apparatus 10 (the image forming section 12, the fixing device 15, and the conveying mechanism 16) will be described below.

[0026] <Image forming unit 12> The image forming unit 12 is a component that forms a toner image on the recording medium P by an electrophotographic method. Specifically, as shown in Fig. 1, the image forming unit 12 has a toner image forming unit 20 that forms a toner image, and a transfer device 13 that transfers the toner image formed in the toner image forming unit 20 onto the recording medium P.

[0027] <Toner image forming unit 20> A plurality of toner image forming units 20 shown in Fig. 1 are provided so as to form toner images for each color. In this embodiment, toner image forming units 20 for a total of four colors, yellow (Y), magenta (M), cyan (C), and black (K), are provided. (Y), (M), (C), and (K) shown in Fig. 1 indicate components corresponding to the above-mentioned respective colors.

[0028] In addition, since the toner image forming units 20 of each color are configured in the same manner except for the toner used, in FIG. 1, the respective parts of the toner image forming unit 20(K) are denoted by reference numerals as a representative of the toner image forming units 20 of each color.

[0029] Specifically, each of the toner image forming units 20 for each color has a photoconductor 22 that rotates in one direction (for example, the counterclockwise direction in FIG. 1). Each of the toner image forming units 20 for each color also has a charger 23, an exposure device 24, and a developing device 25.

[0030] In the toner image forming unit 20 for each color, the charger 23 charges the photoconductor 22. Furthermore, the exposure device 24 exposes the photoconductor 22 charged by the charger 23 to light, thereby forming an electrostatic latent image on the photoconductor 22. Furthermore, the development device 25 develops the electrostatic latent image formed on the photoconductor 22 by the exposure device 24, thereby forming a toner image.

[0031] <Transfer device 13> The transfer device 13 shown in Fig. 1 is a device that transfers the toner image formed in the toner image forming unit 20 onto a recording medium P. Specifically, the transfer device 13 performs primary transfer of the toner images of the photoconductors 22 of each color onto a transfer belt 30 in an overlapping manner, and then performs secondary transfer of the overlapped toner images onto the recording medium P. The transfer belt 30 is an example of a transfer member. As shown in Fig. 1, the transfer device 13 includes the transfer belt 30, a primary transfer roll 32, and a transfer cylinder 40.

[0032] The primary transfer roll 32 is a roll that transfers the toner image of each color of the photoconductor 22 to the transfer belt 30 at a primary transfer position T1 between the photoconductor 22 and the primary transfer roll 32. In this embodiment, a primary transfer electric field is applied between the primary transfer roll 32 and the photoconductor 22, so that the toner image formed on the photoconductor 22 is transferred to the transfer belt 30 at the primary transfer position T1.

[0033] The toner image is transferred from the photoreceptor 22 of each color onto the outer peripheral surface of the transfer belt 30. As shown in Fig. 1, the transfer belt 30 is endless (belt-shaped in Fig. 2), and is wound around a plurality of rolls 33 and a secondary transfer roll 34 (described below) so as to assume an inverted triangular posture when viewed from the front (when viewed toward the depth of the device). The transfer belt 30 rotates in the direction of arrow A when at least one of the plurality of rolls 33 is driven to rotate. In other words, the transfer belt 30 is driven to rotate, and the toner image is transferred onto it.

[0034] The secondary transfer roll 34 is cylindrical and extends in the depth direction. The secondary transfer roll 34 is an example of a transfer roll. The secondary transfer roll 34 transfers a toner image to a recording medium P wound around a transfer cylinder 40 described later while sandwiching the transfer belt 30 with a transfer jacket 44 described later. More specifically, the secondary transfer roll 34 sandwiches the transfer belt 30 with the transfer jacket 44 in a manner that the transfer belt 30 bites into the transfer jacket 44. The secondary transfer roll 34 rotates while pressing the transfer belt 30 from the back side opposite to the side on which the toner image is transferred.

[0035] 1 and 2, the transfer cylinder 40 has a recess 41 formed on its outer circumferential surface 40A, and rotates in a rotation direction B. The recess 41 extends in the axial direction (depth direction) of the transfer cylinder 40, and has a depth along the radial direction of the transfer cylinder 40. The side ends of the recess 41 in the depth direction are ends 41C, 41D, 41E, and 41F, respectively, and the shape of the recess 41 joined together forms a rectangle when viewed from above.

[0036] 1, the transfer cylinder 40 is disposed below the transfer belt 30 and faces the transfer belt 30. Furthermore, the transfer cylinder 40 contacts the transfer belt 30 in the range of the outer peripheral surface 40A from the upstream end 41A to the downstream end 41B in the rotation direction of the recess 41 (see FIG. 4). The upstream end 41A and the downstream end 41B are specifically end portions on the opening side of the recess 41 (i.e., the radially outer side of the transfer cylinder 40).

[0037] 4, the transfer cylinder 40 specifically has a cylinder main body 42 and a transfer jacket 44. The transfer cylinder 40 is disposed on the side of the transfer belt 30 on which the toner image has been transferred.

[0038] The barrel body 42 has a recess 41 formed in a cylindrical surface 42A, which is the outer circumferential surface. Specifically, as shown in Fig. 2, the barrel body 42 is cylindrical and extends in the depth direction, and the cylindrical surface 42A has a recess 41 extending in the depth direction formed therein. A gripper 60 and an attachment member 63, which will be described later, in the transport mechanism 16 are housed in this recess 41. The barrel body 42 is made of a metal material, such as stainless steel or aluminum.

[0039] The transfer jacket 44 is in the form of a sheet wrapped around the cylindrical surface 42A of the barrel body 42 from the upstream end 41A to the downstream end 41B in the rotation direction of the recess 41 as shown in FIG. 4. In other words, the transfer jacket 44 is wrapped around the cylindrical surface 42A in such a manner that both ends are disposed outside the recess 41. The outer peripheral surface 44A of the transfer jacket 44 forms the outer peripheral surface 40A of the transfer barrel 40. The outer peripheral surface 44A of the transfer jacket 44 sandwiches the transfer belt 30 and the recording medium P with the secondary transfer roll 34 described later. In this state, the secondary transfer roll 34 bites into the transfer jacket 44. For example, foamed rubber having an elastic layer and a surface layer is used as the transfer jacket 44. In this embodiment, the transfer jacket 44 is attached to the barrel body 42 in a replaceable manner. More specifically, when the transfer jacket 44 is wrapped around the cylindrical surface 42A of the barrel body 42, the transfer jacket 44 has a predetermined thickness including a base layer, an elastic layer, and a surface layer, which are not shown, in the order of proximity to the cylindrical surface 42A. The transfer jacket 44 is provided with an attachment / detachment jig (not shown) at the end of the base layer (not shown), and is attached to the cylinder body 42 by the attachment / detachment jig. The transfer cylinder 40 repeatedly collides with and separates from the transfer jacket 44 as the secondary transfer roll 34 passes through the recess 41. More specifically, the secondary transfer roll 34 separates from one end 70 of the transfer jacket 44 when entering the recess 41 from the downstream end 41B side, and collides with the other end 72 of the transfer jacket 44 when exiting the recess 41 via the upstream end 41A (see FIG. 2). After this collision, the transfer cylinder 40 sandwiches the transfer belt 30 and the recording medium P between the outer circumferential surface 44A of the transfer jacket 44 and the secondary transfer roll 34 described below, as described above.

[0040] As shown in FIG. 2 and FIG. 4, the transfer jacket 44 has one end 70 on the downstream end 41B side in the rotation direction of the recess 41 of the cylinder body 42 and the other end 72 on the upstream end 41A side, each of which is formed in a triangular shape. Hereinafter, when the one end 70 and the other end 72 of the transfer jacket 44 are described, the above-mentioned elastic layer and surface layer will be described unless otherwise specified. The one end 70 and the other end 72 are an example of the end of the transfer jacket. The one end 70 and the other end 72 of the transfer jacket 44 are determined in the circumferential direction of the cylinder body (the circumferential direction positions of the side ends 70A and 70B, and the side ends 72A and 72B described later) based on the area where an image is formed on the recording medium P (see FIG. 8(a)). Specifically, the one end 70 and the other end 72 are the portions of the transfer jacket 44 located radially inside the marginal portion of the recording medium P wound around the transfer cylinder 40 where no image is formed, or a part of them. 2, both side ends in the depth direction of the transfer jacket 44 (the depth direction positions of side ends 70A and 70B, and side ends 72A and 72B, described below) are aligned along the circumferential direction of the trunk main body 42. For convenience, the following description will be given assuming that an imaginary reference line M is located at the center of the depth direction of both side ends.

[0041] One end 70 of the transfer jacket 44 is formed with a surface extending from a side end 70A on the front side in the depth direction and a side end 70B on the rear side in the depth direction toward the reference line M, forming a triangular shape with an apex angle on the side of the downstream end 41B in the rotation direction of the recess 41 (see FIG. 8(a)). The other end 72 of the transfer jacket 44 is formed with a surface extending from a side end 72A on the front side in the depth direction and a side end 72B on the rear side in the depth direction toward the reference line M, forming a triangular shape with an apex angle on the side of the upstream end 41A in the rotation direction of the recess 41 toward the recess 41. In this embodiment, the shape of the one end 70 and the other end 72 of the transfer jacket 44 is an isosceles triangle. That is, the transfer jacket 44 is hexagonal in the unfolded state.

[0042] As described above, the one end 70 and the other end 72 of the transfer jacket 44 extend in a direction intersecting the depth direction (the direction of the axis of the secondary transfer roll 34), and the one end 70 and the other end 72 each have an edge on the side of the recess 41 that is non-parallel to the axis of the secondary transfer roll 34. In this embodiment, since the one end 70 and the other end 72 each have an isosceles triangular shape, the direction in which the edges of the one end 70 and the other end 72 extend is a direction intersecting the axis of the secondary transfer roll 34 and is non-parallel. Also, as shown in FIG. 2 and FIG. 8(a), it can be said that the length of the side (base) L along the depth direction of the triangular portion of the one end 70 and the other end 72 of the transfer jacket 44 gradually decreases toward the recess 41. The length of the base L is longest when it becomes a line segment connecting the side end 70A and the side end 70B. Furthermore, as one end 70 and the other end 72 of the transfer jacket 44 approach the recess 41, the length of the side along the depth direction of the triangular portion (the length of the foot of the perpendicular line dropped from the side ends 70A, 70B, 72A, and 72B to the reference line M) becomes smaller toward the reference line M.

[0043] When the transfer jacket 44 is wrapped around the barrel body 42, one end 70 and the other end 72 of the transfer jacket 44 face each other across the recess 41, and the shapes of the one end 70 and the other end 72 are equal triangular shapes. The reference line M is a line passing through the center 41H in the depth direction of the downstream end 41B of the recess 41 and the center 41G in the depth direction of the upstream end 41A. Therefore, the one end 70 and the other end 72 are formed symmetrically in the depth direction with the reference line M as the central axis. In other words, the transfer jacket 44 as a whole is formed symmetrically in the depth direction with the reference line M as the central axis.

[0044] When the transfer jacket 44 is wrapped around the cylindrical surface 42A (outer peripheral surface) of the trunk main body 42, areas (hereinafter also referred to as "areas where the base layer of the transfer jacket 44 is exposed") where the transfer jacket 44 is not wrapped around the trunk main body are formed on the upstream end 41A side and the downstream end 41B side of the recess 41 on the trunk main body 42. These areas have a shape corresponding to one end 70 and the other end 72 of the transfer jacket 44. In this embodiment, these areas are in the shape of four right-angled triangles with the one end 70 or the other end 72 of the transfer jacket 44 as the hypotenuse.

[0045] 2, a pair of sprockets 64 are provided on both axial ends of the transfer cylinder 40. The pair of sprockets 64 are arranged coaxially on the transfer cylinder 40. The transfer cylinder 40 rotates in the rotation direction B together with the pair of sprockets 64 as a result of the cylinder main body 42 being rotationally driven by a drive unit (not shown) and rotating in the rotation direction B.

[0046] In this embodiment, the transfer belt 30 and the transfer cylinder 40 convey the recording medium P in a sandwiched state at the secondary transfer position T2 (see FIG. 1). Then, a secondary transfer electric field is applied between the secondary transfer roll 34 and the transfer cylinder 40, so that the toner image transferred onto the transfer belt 30 is transferred onto the recording medium P at the secondary transfer position T2. ​​Note that a gripper 60 and an attachment member 63 (described below) that hold the recording medium P are accommodated in a recess 41 when passing through the secondary transfer position T2, and are prevented from contacting the transfer belt 30.

[0047] <Fixing device 15> In this embodiment, the fixing device 15 is a device that fixes the toner image transferred to the recording medium P by the transfer cylinder 40 to the recording medium P. Specifically, the fixing device 15 has a fixing cylinder 50 and a heating roll 52, as shown in FIG.

[0048] In the fixing device 15, a heating roll 52 is disposed above a fixing cylinder 50. The heating roll 52 has a heat source 54 such as a halogen lamp inside the roll.

[0049] The fixing cylinder 50 has a recess 51 on its outer circumferential surface. This recess 51 is provided on a part of the outer circumferential surface of the fixing cylinder 50 in the circumferential direction. Furthermore, the recess 51 is formed long along the axial direction of the fixing cylinder 50, and has a depth along the radial direction of the fixing cylinder 50. The recess 51 accommodates a gripper 60 and an attachment member 63, which will be described later. This prevents the gripper 60 and the attachment member 63 from coming into contact with the heating roll 52 when they pass through the fixing position NP shown in FIG. 1.

[0050] A pair of sprockets 65 are provided on both axial ends of the fixing cylinder 50. The pair of sprockets 65 are arranged coaxially with the fixing cylinder 50 and are configured to rotate integrally with the fixing cylinder 50.

[0051] Then, in the fixing device 15, the recording medium P is conveyed while being sandwiched between the heating roll 52 and the fixing cylinder 50 at the fixing position NP, and the toner image transferred to the recording medium P is fixed to the recording medium P by heating and pressurizing the recording medium P.

[0052] <Transport mechanism 16> The transport mechanism 16 shown in Fig. 1 is a mechanism for transporting a recording medium P. As shown in Fig. 1 and Fig. 2, the transport mechanism 16 has a pair of chains 66 and a gripper 60. Note that Fig. 1 shows only one of the pair of chains 66, and the chain 66 and the gripper 60 are shown in a simplified form.

[0053] The pair of chains 66 are formed in a ring shape as shown in Fig. 1. The pair of chains 66 are arranged at an interval in the depth direction (direction D in the figure) as shown in Fig. 2. Each of the pair of chains 66 is wound around a pair of sprockets 64 provided on both axial ends of the transfer cylinder 40 and a pair of sprockets 65 (see Fig. 1) provided on both axial ends of the fixing cylinder 50. The transfer cylinder 40 and the pair of sprockets 64 are rotated together in the rotation direction B (direction of arrow B), causing the chain 66 to rotate in the circulation direction C (direction of arrow C).

[0054] 2, a mounting member 63 to which a gripper 60 is attached is hung in the depth direction between the pair of chains 66. A plurality of mounting members 63 are fixed to the pair of chains 66 at predetermined intervals along the circulating direction C of the chains 66.

[0055] As shown in Fig. 2, a plurality of grippers 60 are attached to the attachment member 63 at predetermined intervals along the depth direction. The grippers 60 hold the leading end of the recording medium P. Specifically, as shown in Fig. 3, the grippers 60 have a claw 61 and a claw base 62. The grippers 60 are configured to hold the recording medium P by pinching the leading end of the recording medium P between the claw 61 and the claw base 62. In addition, the grippers 60 have, for example, a claw 61 pressed against the claw base 62 by a spring or the like, and the claw 61 is opened and closed relative to the claw base 62 by the action of a cam or the like.

[0056] In the transport mechanism 16, as shown in FIG. 3, a gripper 60 holds the leading end of the recording medium P sent from a storage unit (not shown) in which the recording medium P is stored. The gripper 60 holding the leading end of the recording medium P transports the recording medium P by rotating the chain 66 in the rotation direction C, and passes the secondary transfer position T2 and the fixing position NP. Then, the toner images of each color that have been primarily transferred onto the transfer belt 30 in a superimposed manner at the primary transfer position T1 are secondarily transferred onto the recording medium P at the secondary transfer position T2. ​​The toner images secondarily transferred onto the recording medium P are fixed onto the recording medium P at the fixing position NP.

[0057] In addition, when gripper 60 passes through secondary transfer position T2, it is accommodated together with mounting member 63 in recess 41 formed on the outer peripheral surface of transfer cylinder 40, and when it passes through fixing position NP, it is accommodated together with mounting member 63 in recess 51 formed on the outer peripheral surface of fixing cylinder 50.

[0058] <Effects of this embodiment> 5, in the transfer device 13 of this embodiment, the secondary transfer roll 34 transfers a toner image to the recording medium P wrapped around the transfer cylinder 40 while repeatedly colliding with and separating from the transfer jacket 44 of the transfer cylinder 40. In the image forming apparatus 10, the toner image transferred to the recording medium P is fixed by the fixing device 15. Here, in the transfer device 13, the secondary transfer roll collides with the other end 72 of the transfer jacket 44 as it retreats from the recess 41, and the transfer belt 30 and the recording medium P are sandwiched between the transfer jacket 44 and the secondary transfer roll .

[0059] 2 and 5, when the secondary transfer roll 34 collides with the other end 72 of the transfer jacket 44, the secondary transfer roll 34 collides with the other end 72 in order from the portion on the reference line M that is closest to the upstream end 41A of the recess 41. After colliding with the portion, the secondary transfer roll 34 rotates relatively along the triangular shape of the other end 72 toward the one end 70 side of the transfer jacket 44 that rotates in the B direction together with the transfer cylinder 40 while sandwiching the transfer belt 30 and the recording medium P, and transfers the toner image to the recording medium P. The contact length between the outer circumferential surface 44A of the transfer jacket 44 and the transfer belt 30 and recording medium P pressed against the secondary transfer roll 34 gradually increases in the triangular portion as the transfer cylinder 40 rotates in the B direction, so that the load from the transfer jacket 44 to the secondary transfer roll 34 gradually increases.

[0060] In the transfer device 13 of this embodiment, when the transfer cylinder 40 rotates in the rotation direction B from the state shown in FIG. 5, the secondary transfer roll 34 reaches the state shown in FIG.

[0061] Specifically, referring to FIG. 2 and FIG. 6, the transfer cylinder 40 rotates in the B direction to a position where the secondary transfer roll 34 presses the side ends 70A, 70B of the transfer jacket 44 while the secondary transfer roll 34 presses the transfer belt 30 and the recording medium P against the transfer jacket 44. Since the one end 70 including the side ends 70A, 70B is triangular, the contact length with the outer circumferential surface 44A of the transfer jacket 44 decreases from that position toward the downstream end 41B of the recess 41 as the transfer cylinder 40 rotates in the B direction. In other words, the load from the transfer jacket 44 to the secondary transfer roll 34 gradually decreases. Thereafter, as the secondary transfer roll 34 passes through the recess 41, the secondary transfer roll 34 separates from the transfer jacket 44 and the secondary transfer roll 34 leaves the downstream end 41B of the recess 41.

[0062] According to the transfer device 13 of this embodiment, the load fluctuation of the transfer belt 30 is suppressed compared to a configuration in which both ends (one end 70 and the other end 72) of the transfer jacket 44 are parallel to the axis of the secondary transfer roll 34, i.e., a configuration in which collision or separation of the secondary transfer roll 34 occurs simultaneously throughout the entire axial direction of the transfer jacket 44.

[0063] 2, in the transfer device 13 of this embodiment, the transfer jacket 44 is symmetrical about the reference line M, and the secondary transfer roll 34 collides with the other end 72 of the transfer jacket 44 from above the reference line M, and passes through the recess 41 from the one end 70 from above the reference line M. Therefore, compared to a configuration in which the transfer jacket is asymmetric, axial skewing of the transfer belt 30 accompanying the rotation of the transfer cylinder 40 is suppressed.

[0064] In the transfer device 13 of this embodiment, one end 70 or the other end 72 of the transfer jacket 44 extends from both ends in the depth direction toward the reference line M as it moves toward the recess 41. Therefore, processing of one end of the transfer jacket 44 is easier than in a configuration in which one end of the transfer jacket 44 extends toward multiple points.

[0065] In the transfer device 13 of this embodiment, one end 70 and the other end 72 of the transfer jacket 44 are non-parallel to the axis of the secondary transfer roll 34. Therefore, compared to a configuration in which only one end is non-parallel to the axis of the secondary transfer roll 34, load fluctuations on the transfer belt 30 due to both collision with and separation from the transfer jacket 44 by the secondary transfer roll 34 are suppressed.

[0066] In the transfer device 13 of this embodiment, the transfer jacket 44 is replaceably attached to the body 42, so that it is easier to change the specifications of the end of the transfer jacket 44 (one end 70 or the other end 72) compared to when the transfer jacket 44 is fixed to the body 42.

[0067] In addition, since the image forming apparatus 10 of this embodiment is equipped with the transfer device 13 of this embodiment, distortion of the image formed on the recording medium P caused by the secondary transfer roll 34 repeatedly colliding with and separating from the transfer jacket 44 as it passes through the recess 41 is suppressed.

[0068] <Second embodiment> A configuration of an image forming apparatus 10 according to another embodiment of the present disclosure (hereinafter referred to as the "second embodiment") will be described. The second embodiment has a basic configuration in common with the configuration according to the present embodiment, and therefore a description of the common configuration will be omitted.

[0069] 7 is an image forming apparatus 10 in this embodiment in which covers 74, 76 are provided in the area where the base layer of the transfer jacket 44 is exposed. The covers 74, 76 cover the portion between one end 70 or the other end 72 of the transfer jacket 44 and the recess 41. The covers 74, 76 are an example of a covering portion.

[0070] The covers 74, 76 are formed in a triangular shape and have a lower elastic modulus than the transfer jacket 44. The covers 74, 76 have a thickness equivalent to that of the transfer jacket 44, but the covers 74, 76 may be tapered. The cover 74 covers two exposed areas of the base layer of the transfer jacket 44 between one end 70 of the transfer jacket 44 and the downstream end 41B of the recess 41. The cover 76 covers two exposed areas between the other end 72 of the transfer jacket 44 and the upstream end 41A of the recess 41. The covers 74 and 76 have a common size and shape.

[0071] <Effects of the Second Embodiment> In the transfer device 13 of the second embodiment, when the secondary transfer roll 34 collides with the other end 72, the secondary transfer roll 34 collides with a portion of the other end 72 on the reference line M that is closest to the upstream end 41A of the recess 41, and a portion on the upstream end 41A side of the cover 76. Also, when the secondary transfer roll 34 separates from the one end 70, the cover 74 bears the pressing force of the secondary transfer roll 34. Therefore, deterioration of the one end 70 and the other end 72 of the transfer jacket 44 is suppressed compared to the configuration of this embodiment.

[0072] <Modification> In the image forming apparatus 10 according to the present embodiment, the one end 70 and the other end 72 of the transfer jacket 44 have a common triangular shape, but the shape is not limited to this. The one end 70 and the other end 72 may have different triangular shapes. Specifically, the one end 70 may have a right-angled isosceles triangle shape, and the other end 72 may have an obtuse-angled isosceles triangle shape. These shapes are preferably set based on the image forming area. In this case, compared to a configuration in which the shapes of both ends of the transfer jacket 44 are common, load fluctuations are suppressed according to the shapes of the one end 70 and the other end 72. In addition, a triangular shape may be formed on either the one end 70 or the other end 72. Furthermore, the one end 70 and the other end 72 are not limited to a shape extending linearly from both ends toward the reference line M, and may be an arc or wavy shape.

[0073] Below, a modified example will be described for one end 70 of the transfer jacket 44, but it can also be applied to the other end 72. As shown in FIG. 8(a), one end 70 of the transfer jacket 44 is formed with a surface from the side end 70A and the side end 70B toward the reference line M, but this is not limited to this. For example, the one end 70 may be an asymmetric triangular shape. As shown in FIG. 8(b), one end 70 of the transfer jacket 44 may be formed with a surface from the reference line M toward the side end 70A and the side end 70B, respectively. In this case, the base L in the above-mentioned embodiment corresponds to the sum of the line segment L1 and the line segment L2. The length of the line segment L1 and the line segment L2 are the same, and the sum of the line segment L1 and the line segment L2 is the contact length. Also, as shown in FIG. 8(c), one end 70 of the transfer jacket 44 may be provided on both side ends (70A and 70B) in addition to on the reference line M, so that the entire one end 70 is formed in a W-shape (triangular wave shape) when viewed from above. In this case, it is preferable to provide the end 70E or the end 70D between the reference line M and the depth direction (left and right direction in the figure) of each of the side end 70A or the side end 70B so as to be symmetrical with respect to the reference line M. In this case, the base L in the above-mentioned embodiment corresponds to the sum of the line segments L1, L2, and L3. The entire one end 70 may be a sine wave or the like when viewed from above. As shown in FIG. 8(d), the one end 70 of the transfer jacket 44 is triangular, but may be trapezoidal. That is, the edges of the one end 70 and the other end 72 of the transfer jacket 44 are not limited to a configuration in which the entire depth direction is non-parallel to the axis of the secondary transfer roll 34, and may be partially non-parallel. Specifically, when a part of the edge in the depth direction is parallel and the rest is non-parallel, the edge is trapezoidal, for example, and when the entire depth direction of the edge is non-parallel, the edge is a right-angled triangle (single-inclined) with the entire edge as the hypotenuse, for example.

[0074] The transfer jacket 44 has a set thickness including a base layer, an elastic layer, and a surface layer, not shown, in that order from closest to the cylindrical surface 42A, when wrapped around the cylindrical surface 42A of the trunk main body 42, but is not limited to this. For example, when the transfer jacket 44 is wrapped around the cylindrical surface 42A of the trunk main body 42, one end 70 or the other end 72 may be formed in a tapered shape so that the thickness decreases toward the recess 41.

[0075] The present disclosure is not limited to the above-described embodiment, and various modifications, changes, and improvements are possible without departing from the spirit of the present disclosure. For example, the above-described modified examples may be appropriately combined to form a configuration, and the transfer jacket 44 may be asymmetrical with respect to the reference line M, or may be non-replaceable with respect to the trunk body 42.

[0076] <Additional Notes> (((1))) a transfer member formed in an endless belt shape onto which a toner image is transferred; A transfer cylinder including a cylinder body having an axially extending recess formed on an outer peripheral surface thereof, and a transfer jacket wrapped around the outer peripheral surface in such a manner that both ends are disposed outside the recess; a transfer roll extending in the axial direction and transferring a toner image to a recording medium wound around the transfer cylinder while sandwiching the transfer member between the transfer roll and the transfer jacket, the transfer roll repeatedly colliding with and separating from the transfer jacket as the transfer roll passes through the recess; Equipped with At least one of the two ends of the transfer jacket has an edge that is not parallel to the axis of the transfer roll. Transcription device. (((2))) The transfer jacket is formed symmetrically with respect to the center in the axial direction. The transfer device according to (((1))). (((3))) The one end of the transfer jacket extends from both ends in the axial direction toward the recess toward the center to form a triangular shape. The transfer device according to (((2))). (((4))) Both ends of the transfer jacket have edges that are not parallel to the axis of the transfer roll. The transfer device according to any one of (((1))) to (((3))). (((5))) The shapes of both ends of the transfer jacket are different from each other. The transfer device according to any one of (((1))) to (((4))). (((6))) The transfer jacket is replaceably attached to the barrel body. The transfer device according to any one of (((1))) to (((5))). (((7))) a cover portion that covers a portion between at least one of both end portions of the transfer jacket and the recess and has a lower elastic modulus than the one end portion of the transfer jacket; The transfer device according to any one of (((1))) to (((6))). (((8))) an image forming unit that forms the toner image and a transfer device according to any one of (((1))) to (((7))); a fixing device that fixes the image transferred onto the recording medium by the image forming unit; An image forming apparatus comprising:

[0077] According to the configuration (((1))), the load fluctuation of the transfer member is suppressed compared to the configuration in which the axis of the transfer roll and the end of the transfer jacket are parallel to each other. According to the configuration (((2))), as compared with the configuration in which the transfer jacket is asymmetric, axial inclination of the transfer member caused by rotation of the transfer cylinder is suppressed. According to the configuration (((3))), processing of one end of the transfer jacket is simplified compared to a configuration in which one end extends toward a plurality of points. According to the configuration (((4))), the load fluctuation of the transfer member due to both the collision of the transfer roll with respect to the transfer jacket and the separation of the transfer roll are suppressed, compared to a configuration in which only one end is non-parallel to the axis of the transfer roll. According to the configuration (((5))), load fluctuations are suppressed according to the shape of each end, compared to a configuration in which both ends of the transfer jacket have the same shape. According to the configuration (((6))), it is easier to change the specifications of the end portion of the transfer jacket compared to when the transfer jacket is fixed to the barrel body. According to the configuration (((7))), deterioration of the end portion of the transfer jacket is suppressed compared to a configuration in which the end portion is exposed to the outer peripheral surface of the body member while remaining non-parallel to the axis of the transfer roll. The configuration of (((8))) suppresses distortion of the image formed on the recording medium caused by repeated collision with and separation from the transfer jacket as the transfer roll passes through the recess. [Explanation of symbols]

[0078] 10 Image forming device 12 Image forming section 13 Transcription device 15 Fixing device 16 Conveyor mechanism 20 Toner image forming unit (an example of an image forming unit) 22 Photoreceptor 23 Charger 24 Exposure equipment 25 Developing device 30 Transfer belt (an example of a transfer member) 32 Primary transfer roll 33 Rolls 34 Secondary transfer roll (an example of a transfer roll) 40 Transfer cylinder 41 Recess 42 Body 44 Transfer Jacket 50 Fixed torso 51 Recess 52 Heating roll 54 Heating source 60 Gripper 61 Nails 62 Nail stand 63 Mounting material 64, 65 sprockets 66 Chain 70 One end (an example of an end) 72 Other end (an example of an end) 74, 76 Cover (an example of a cover) P Recording medium

Claims

1. a transfer member formed in an endless belt shape onto which a toner image is transferred; A transfer cylinder including a cylinder body having an axially extending recess formed on an outer peripheral surface thereof, and a transfer jacket wrapped around the outer peripheral surface in such a manner that both ends are disposed outside the recess; a transfer roll extending in the axial direction and transferring a toner image to a recording medium wound around the transfer cylinder while sandwiching the transfer member between the transfer roll and the transfer jacket, the transfer roll repeatedly colliding with and separating from the transfer jacket as the transfer roll passes through the recess; Equipped with At least one of the two ends of the transfer jacket has an edge that is not parallel to the axis of the transfer roll. Transcription device.

2. The transfer jacket is formed symmetrically with respect to the center in the axial direction. The transfer device according to claim 1 .

3. The one end of the transfer jacket extends from both ends in the axial direction toward the recess toward the center to form a triangular shape. The transfer device according to claim 2 .

4. Both ends of the transfer jacket have edges that are not parallel to the axis of the transfer roll. The transfer device according to claim 1 .

5. The shapes of both ends of the transfer jacket are different from each other. The transfer device according to claim 4 .

6. The transfer jacket is replaceably attached to the barrel body. The transfer device according to claim 1 .

7. a cover portion that covers a portion between at least one of both end portions of the transfer jacket and the recess and has a lower elastic modulus than the one end portion of the transfer jacket; The transfer device according to claim 1 .

8. an image forming section including the toner image forming unit and the transfer device according to any one of claims 1 to 7; a fixing device that fixes the image transferred onto the recording medium by the image forming unit; An image forming apparatus comprising:

Images