Transfer device and image forming apparatus

Abstract

A transfer device includes: a transfer member formed in an endless belt shape and transferring a toner image; a transfer cylinder having a cylinder main body in which a recessed portion extending in the axial direction is formed on the outer peripheral surface, and a transfer sleeve wound around the outer peripheral surface such that both end portions are disposed outside the recessed portion; and a transfer roller that extends in the axial direction, sandwiches the transfer member with the transfer sleeve, transfers a toner image on the recording medium wound around the transfer cylinder, and repeatedly collides with and separates from the transfer sleeve as the transfer roller passes through the recess. At least one of the two end portions of the transfer sleeve is provided with an edge which is not parallel to the axis of the transfer roller.

Description

Technical Field

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

[0002] Patent Document 1 discloses an image forming apparatus including a transfer cylinder and having a tapered surface on the transfer cylinder.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2023-59720

[0004] In an image forming device equipped with a transfer device, in a structure in which the transfer roller and the transfer sleeve of the transfer cylinder repeatedly collide and separate as the transfer roller passes through the recessed portion of the transfer cylinder, load fluctuations occur on the transfer component clamped by the transfer roller and the transfer sleeve when the transfer roller collides or separates from the transfer sleeve. Summary of the invention

[0005] An object of the present invention is to suppress load fluctuations on a transfer member, as compared with a structure in which both end portions of a transfer sleeve are parallel to the axis of a transfer roller.

[0006] The transfer device involved in the first embodiment of the present invention comprises: a transfer member formed in an annular belt shape and transferring a toner image; a transfer cylinder having a cylinder body and a transfer sleeve, the cylinder body having a recessed portion extending in an axial direction formed on the outer peripheral surface, the transfer sleeve being wound on the outer peripheral surface with both ends arranged on the outside of the recessed portion; and a transfer roller extending in the axial direction and clamping the transfer member with the transfer sleeve, and transferring the toner image on a recording medium wound on the transfer cylinder, and repeatedly colliding and separating with the transfer sleeve as it passes through the recessed portion, and at least one of the two ends of the transfer sleeve has an edge that is not parallel to the axis of the transfer roller.

[0007] According to the transfer device described in the first aspect, in the transfer device according to the second aspect of the present invention, the transfer sleeve is formed symmetrically with respect to the center in the axial direction.

[0008] In the transfer device according to the second aspect, in the transfer device according to the third aspect of the present invention, the one end portion of the transfer sleeve forms a triangular shape as it extends from both side ends in the axial direction toward the recessed portion toward the center.

[0009] According to a fourth aspect of the transfer device described in any one of the first to third aspects, both ends of the transfer sleeve have edges that are not parallel to the axis of the transfer roller.

[0010] According to the transfer device described in any one of the first to fourth aspects, in a transfer device according to a fifth aspect of the present invention, shapes of both end portions of the transfer sleeve are different.

[0011] In the transfer device according to any one of the first to fifth aspects, a sixth aspect of the present invention is characterized in that the transfer sleeve is replaceably mounted on the cartridge body.

[0012] According to the transfer device described in any one of the first to sixth aspects, the transfer device involved in the seventh aspect of the present invention comprises: a covering portion, which covers the portion between at least one of the two end portions of the transfer sleeve and the recessed portion, and has an elastic modulus lower than that of the one end portion of the transfer sleeve.

[0013] The image forming device involved in the 8th mode of the present invention comprises: an image forming unit, which has an image forming unit that forms the toner image, and a transfer device described in any one of the 1st to 7th modes; and a fixing device that fixes the image transferred by the image forming unit to the recording medium.

[0014] Effects of the Invention

[0015] According to the transfer device according to the first aspect of the present invention, load fluctuation of the transfer member is suppressed compared to a configuration in which the axis of the transfer roller and the end of the transfer sleeve are parallel.

[0016] According to the transfer device according to the second aspect of the present invention, compared with a structure in which the transfer sleeve is asymmetrical, the transfer member is prevented from tilting in the axial direction as the transfer cylinder rotates.

[0017] According to the transfer device according to the third aspect of the present invention, compared with a configuration in which one end portion of the transfer sleeve extends toward a plurality of points, processing of the one end portion becomes simpler.

[0018] According to the transfer device according to the fourth aspect of the present invention, compared with a configuration in which only one end portion is not parallel to the axis of the transfer roller, both collision and separation between the transfer roller and the transfer sleeve suppress load fluctuations of the transfer member.

[0019] According to the transfer device according to the fifth aspect of the present invention, load fluctuation is suppressed according to the shape of each end portion, compared with a configuration in which both end portions of the transfer sleeve have the same shape.

[0020] According to the transfer device according to the sixth aspect of the present invention, it is easier to change the specifications of the end portion of the transfer sleeve than in the case where the transfer sleeve is fixed to the drum body.

[0021] According to the transfer device according to the seventh aspect of the present invention, degradation of the end portion is suppressed compared to a configuration in which the end portion of the transfer sleeve is exposed to the outer peripheral surface of the cylinder member in a state not parallel to the axis of the transfer roller.

[0022] According to the image forming apparatus of the eighth aspect of the present invention, disturbance of the image formed on the recording medium caused by repeated collision and separation between the transfer roller and the transfer sleeve as the transfer roller passes through the concave portion is suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Embodiments of the present invention will be described in detail with reference to the following drawings.

[0024] Figure 1 is a schematic diagram showing an image forming apparatus according to an embodiment of the present invention;

[0025] Figure 2 is a perspective view showing the structure of the periphery of a transfer cylinder according to an embodiment of the present invention;

[0026] Figure 3 is a perspective view showing a clamper according to an embodiment of the present invention;

[0027] Figure 4 is a schematic diagram showing the positional relationship between the transfer cylinder and the secondary transfer roller according to an embodiment of the present invention;

[0028] Figure 5 is a schematic diagram showing a state in which a secondary transfer roller rests on an upstream end of a concave portion of a transfer cylinder according to an embodiment of the present invention;

[0029] Figure 6 is a schematic diagram showing a state in which a transfer roller is separated from a downstream end of a concave portion of a transfer cylinder according to an embodiment of the present invention;

[0030] Figure 7 is a perspective view showing the structure of the periphery of a transfer cylinder according to another embodiment of the present invention;

[0031] Figure 8 (a) is a first example showing the periphery of the upstream end of the transfer sleeve according to the embodiment of the present invention. Figure 8 (b) represents the second example. Figure 8 (c) represents the third example, Figure 8 (d) is a schematic top view showing the fourth example.

[0032] Explanation of symbols

[0033] 10-image forming device, 12-image forming unit, 13-transfer device, 15-fixing device, 16-transport mechanism, 20-toner image forming unit (an example of an image forming unit), 22-photoreceptor, 23-charger, 24-exposure device, 25-developing device, 30-transfer belt (an example of a transfer member), 32-primary transfer roller, 33-roller, 34-secondary transfer roller (an example of a transfer roller), 40- Transfer cylinder, 41-concave portion, 42-cylinder body, 44-transfer sleeve, 50-fixing cylinder, 51-concave portion, 52-heating roller, 54-heating source, 60-clamp, 61-claw, 62-claw frame, 63-mounting component, 64, 65-sprocket, 66-chain, 70-one end portion (an example of an end portion), 72-the other end portion (an example of an end portion), 74, 76-cover (an example of a covering portion), P-recording medium. DETAILED DESCRIPTION

[0034] Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

[0035] <Image Forming Apparatus 10 >

[0036] The configuration of an image forming apparatus 10 according to an embodiment of the present invention (hereinafter referred to as “this embodiment”) will be described. Figure 1 1 is a schematic diagram showing the structure of the image forming apparatus 10 involved in the present embodiment. In addition, for the sake of convenience, the arrow H shown in each figure indicates the vertical direction and the device up and down direction, the arrow W indicates the horizontal direction and the device width direction, and the arrow D indicates the horizontal direction and the device depth direction (device front and back direction). The device depth direction is an example of the axial direction. The dimension ratios of the parts in the H direction, W direction, and D direction shown in each figure may be different from the actual dimension ratios.

[0037] Figure 1 The image forming apparatus 10 shown is an image forming apparatus that forms a toner image (an example of an image) on a recording medium P. Specifically, the image forming apparatus 10 includes an image forming unit 12, a fixing device 15, and a conveying mechanism 16. Hereinafter, each unit of the image forming apparatus 10 (the image forming unit 12, the fixing device 15, and the conveying mechanism 16) will be described.

[0038] <Image Forming Unit 12 >

[0039] The image forming unit 12 is a component that forms a toner image on the recording medium P by electrophotography. Figure 1 As shown, the image forming section 12 includes a toner image forming section 20 for forming a toner image and a transfer device 13 for transferring the toner image formed by the toner image forming section 20 to a recording medium P.

[0040] <Toner Image Forming Section 20 >

[0041] Figure 1 The toner image forming units 20 shown are provided in plurality so as to form toner images for each color. In the present embodiment, toner image forming units 20 for four colors, namely yellow (Y), magenta (M), cyan (C), and black (K), are provided. Figure 1 The (Y), (M), (C), and (K) shown here represent components corresponding to the above-mentioned colors.

[0042] The toner image forming units 20 of the respective colors have the same structure except for the toner used. Therefore, the toner image forming units 20 of the respective colors are used as representatives. Figure 1 In FIG. 1 , each part of the toner image forming section 20 (K) is denoted by a reference numeral.

[0043] Specifically, the toner image forming section 20 of each color has a toner image forming section 21 extending in one direction (for example, Figure 1 The photosensitive body 22 rotates in the counterclockwise direction (in the direction of rotation). The toner image forming section 20 of each color includes a charger 23, an exposure device 24, and a developing device 25.

[0044] In the toner image forming section 20 of each color, the charger 23 charges the photoconductor 22. Then, the exposure device 24 exposes the photoconductor 22 charged by the charger 23 to form an electrostatic latent image on the photoconductor 22. Then, the developing device 25 develops the electrostatic latent image formed on the photoconductor 22 by the exposure device 24 to form a toner image.

[0045] <Transfer device 13>

[0046] Figure 1 The transfer device 13 shown in the figure is a device for transferring the toner image formed by the toner image forming unit 20 to the recording medium P. Specifically, the transfer device 13 transfers the toner images of the photosensitive bodies 22 of each color onto the transfer belt 30 for primary transfer, and transfers the overlapped toner images onto the recording medium P for secondary transfer. The transfer belt 30 is an example of a transfer member. Figure 1 As shown, the transfer device 13 includes a transfer belt 30 , a primary transfer roller 32 , and a transfer cylinder 40 .

[0047] The primary transfer roller 32 is a roller that transfers the toner image of each color of the photoreceptor 22 to the transfer belt 30 at the primary transfer position T1 between the photoreceptor 22 and the primary transfer roller 32. In the present embodiment, by applying a primary transfer electric field between the primary transfer roller 32 and the photoreceptor 22, the toner image formed on the photoreceptor 22 is transferred to the transfer belt 30 at the primary transfer position T1.

[0048] The toner image is transferred from the photoconductor 22 of each color to the outer peripheral surface of the transfer belt 30. Figure 1 As shown, the transfer belt 30 is annular ( Figure 2 The transfer belt 30 is in a belt shape (in the figure), and is wound around a plurality of rollers 33 and a secondary transfer roller 34 described later in a manner that forms an inverted triangle shape when viewed from the front (when viewed in the depth direction of the device). When at least one of the plurality of rollers 33 is driven to rotate, the transfer belt 30 is wound in the direction of arrow A. That is, the transfer belt 30 is driven to rotate, and the toner image is transferred.

[0049] The secondary transfer roller 34 is cylindrical and extends in the depth direction. The secondary transfer roller 34 is an example of a transfer roller. The secondary transfer roller 34 sandwiches the transfer belt 30 with a transfer sleeve 44 described later, and transfers a toner image onto a recording medium P wound around a transfer cylinder 40 described later. More specifically, the secondary transfer roller 34 sandwiches the transfer belt 30 with the transfer sleeve 44 in a manner of biting into the transfer sleeve 44. The secondary transfer roller 34 rotates in a state of pressing the transfer belt 30 from the back side opposite to the side on which the toner image is transferred.

[0050] like Figure 1 and Figure 2 As shown in the figure, the transfer cylinder 40 has a recessed portion 41 formed on the outer peripheral surface 40A, and rotates in the rotation direction B. The recessed portion 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. In addition, the side ends of the recessed portion 41 in the depth direction are end portions 41C, 41D, 41E, and 41F, respectively, and the shape connecting these four end portions is rectangular in a plan view.

[0051] like Figure 1 As shown, the transfer cylinder 40 is arranged on the lower side of the transfer belt 30 so as to face the transfer belt 30. The transfer cylinder 40 is in contact with 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 concave portion 41 (see FIG. Figure 4 Specifically, the upstream end 41A and the downstream end 41B are ends on the opening side of the recessed portion 41 (ie, radially outer sides of the transfer cylinder 40 ).

[0052] Specifically, if Figure 4 As shown, the transfer cylinder 40 includes a cylinder body 42 and a transfer sleeve 44. The transfer cylinder 40 is disposed on one surface side of the transfer belt 30 to which the toner image is transferred.

[0053] The cylinder body 42 has a concave portion 41 formed on its outer peripheral surface, that is, the cylindrical surface 42A. Figure 2As shown, the cylinder body 42 is cylindrical and extends in the depth direction, and a recess 41 extending in the depth direction is formed on the cylinder surface 42A. The clamper 60 and the mounting member 63 described later in the conveying mechanism 16 are accommodated in the recess 41. For example, the cylinder body 42 is formed of a metal material such as stainless steel or aluminum.

[0054] like Figure 4 As shown, the transfer sleeve 44 is a sheet-shaped device that winds the cylindrical surface 42A of the cylinder body 42 from the upstream end 41A in the rotation direction of the recess 41 to the downstream end 41B. That is, the transfer sleeve 44 is wound on the cylindrical surface 42A in a manner in which both ends are arranged on the outside of the recess 41. The outer peripheral surface 40A of the transfer cylinder 40 is formed by the outer peripheral surface 44A of the transfer sleeve 44. The outer peripheral surface 44A of the transfer sleeve 44 clamps the transfer belt 30 and the recording medium P with the secondary transfer roller 34 described later. In this state, the secondary transfer roller 34 bites into the transfer sleeve 44. As the transfer sleeve 44, for example, a foam rubber having an elastic layer and a surface layer is used. In the present embodiment, the transfer sleeve 44 is replaceably mounted on the cylinder body 42. In more detail, the transfer sleeve 44 has a predetermined thickness and includes a base layer, an elastic layer, and a surface layer (not shown) in the order close to the cylindrical surface 42A when wound on the cylindrical surface 42A of the cylinder body 42. On the transfer sleeve 44, a loading and unloading clamp (not shown) is provided at the end of the base layer (not shown), and the transfer sleeve 44 is mounted on the cylinder body 42 by the loading and unloading clamp. As the secondary transfer roller 34 passes through the recess 41, the transfer cylinder 40 and the transfer sleeve 44 repeatedly collide and separate. More specifically, the secondary transfer roller 34 separates from one end 70 of the transfer sleeve 44 when entering the recess 41 from the downstream end 41B side, and collides with the other end 72 of the transfer sleeve 44 when exiting from the recess 41 via the upstream end 41A (refer to Figure 2 After the collision, as described above, the transfer cylinder 40 sandwiches the transfer belt 30 and the recording medium P using the outer peripheral surface 44A of the transfer sleeve 44 and the secondary transfer roller 34 described later.

[0055] like Figure 2 and Figure 4 As shown, the transfer sleeve 44 has one end 70 on the downstream end 41B side and the other end 72 on the upstream end 41A side in the rotation direction of the recessed portion 41 of the tube body 42, respectively, formed in a triangular shape. Hereinafter, when describing the one end 70 and the other end 72 of the transfer sleeve 44, except for cases where there are special instructions, the description is of the elastic layer and the surface layer mentioned above. The one end 70 and the other end 72 are examples of ends of the transfer sleeve. The one end 70 and the other end 72 of the transfer sleeve 44 set the circumferential position of the tube body (the circumferential positions of the side ends 70A and 70B described later, and the side ends 72A and 72B) based on the area where the image is formed on the recording medium P, respectively (refer to Figure 8Specifically, the portion of the transfer sleeve 44 located radially inward of the blank portion where no image is formed in the recording medium P wound around the transfer cylinder 40 or a portion thereof is one end portion 70 and the other end portion 72. Figure 2 As shown, the two side ends in the depth direction of the transfer sleeve 44 (the positions of the side ends 70A and 70B and the side ends 72A and 72B in the depth direction described later) are along the circumference of the barrel body 42. For convenience, it is assumed that there is an imaginary reference line M in the center of the depth direction of the two side ends, and the following description is given.

[0056] One end portion 70 of the transfer sleeve 44 is formed with a surface from a side end portion 70A on the front side in the depth direction and a side end portion 70B on the back side in the depth direction toward the reference line M, thereby forming a triangular shape having a vertex angle on the side of the recess 41 at the downstream end 41B side in the rotation direction of the recess 41 (reference Figure 8 (a)). The other end 72 of the transfer sleeve 44 is formed with a surface from the side end 72A on the front side in the depth direction and the side end 72B on the inner side in the depth direction toward the reference line M, thereby forming a triangular shape with a vertex angle on the side of the recess 41 on the upstream end 41A side in the rotation direction of the recess 41. In this embodiment, the shapes of the one end 70 and the other end 72 of the transfer sleeve 44 are isosceles triangles. That is, the transfer sleeve 44 forms a hexagonal shape in the unfolded state.

[0057] As described above, the one end 70 and the other end 72 of the transfer sleeve 44 extend in a direction intersecting the depth direction (the direction of the axis of the secondary transfer roller 34), and the one end 70 and the other end 72 have edges on the side of the recess 41 that are not parallel to the axis of the secondary transfer roller 34. In this embodiment, since the one end 70 and the other end 72 are each in the shape of an isosceles triangle, 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 roller 34, and are not parallel. And, as Figure 2 and Figure 8 As shown in (a), it can also be said that the length of the side (base) L of the one end 70 and the other end 72 of the transfer sleeve 44 along the depth direction of the triangular shaped portion gradually decreases as they approach the recessed portion 41. In addition, the length of the base L is longest when it becomes a line segment connecting the side end 70A and the side end 70B. Moreover, the length of the side of the one end 70 and the other end 72 of the transfer sleeve 44 along the depth direction of the triangular shaped portion (the length of the foot of the perpendicular from the side ends 70A, 70B, 72A and 72B to the reference line M) decreases toward the reference line M as they approach the recessed portion 41.

[0058] The one end portion 70 and the other end portion 72 of the transfer sleeve 44 are opposed to each other across the recess 41 when the transfer sleeve 44 is wound around the drum body 42, and the one end portion 70 and the other end portion 72 are identical triangular shapes. The reference line M is a line passing through the center 41H in the depth direction of the downstream end 41B and the center 41G in the depth direction of the upstream end 41A in the recess 41. Therefore, the one end portion 70 and the other end portion 72 are formed symmetrically in the depth direction with the reference line M as the center axis. That is, the transfer sleeve 44 as a whole is also formed symmetrically in the depth direction with the reference line M as the center axis.

[0059] When the transfer sleeve 44 is wound around the cylindrical surface 42A (outer peripheral surface) of the cylinder body 42, an area where the transfer sleeve 44 is not wound around the cylinder body is formed on the cylinder body 42 at the upstream end 41A side and the downstream end 41B side of the recess 41 (hereinafter also referred to as "an area where the base layer of the transfer sleeve 44 is exposed"). This area is a shape corresponding to one end 70 and the other end 72 of the transfer sleeve 44. In the present embodiment, this area is a shape of four right triangles with one end 70 or the other end 72 of the transfer sleeve 44 as the hypotenuse.

[0060] And, if Figure 2 As shown, a pair of sprockets 64 are provided at both axial ends of the transfer cylinder 40. The pair of sprockets 64 are arranged coaxially with the transfer cylinder 40. The cylinder body 42 is driven by a driving unit (not shown) to rotate in the rotation direction B, and the transfer cylinder 40 and the pair of sprockets 64 rotate in the rotation direction B integrally.

[0061] In this embodiment, the transfer belt 30 and the transfer cylinder 40 convey the recording medium P in a state of sandwiching the recording medium P at the secondary transfer position T2 (see FIG. 1 ). Figure 1 ). Then, by applying a secondary transfer electric field between the secondary transfer roller 34 and the transfer cylinder 40, the toner image transferred onto the transfer belt 30 is transferred onto the recording medium P at the secondary transfer position T2. ​​In addition, the clamper 60 and the mounting member 63 to be described later for holding the recording medium P are accommodated in the recess 41 when passing through the secondary transfer position T2, thereby avoiding contact with the transfer belt 30.

[0062] <Fixing device 15>

[0063] 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 on the recording medium P. Specifically, Figure 1 As shown, the fixing device 15 includes a fixing cylinder 50 and a heating roller 52 .

[0064] In the fixing device 15, the heating roller 52 is arranged on the upper side with respect to the fixing cylinder 50. The heating roller 52 has a heat source 54 such as a halogen lamp inside the roller.

[0065] The fixing cylinder 50 has a recess 51 on its outer peripheral surface. The recess 51 is provided at a portion of the outer peripheral surface of the fixing cylinder 50 in the circumferential direction. Moreover, 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 the clamp 60 and the mounting member 63 described later. Figure 1 At the fixing position NP shown, contact with the heating roller 52 is avoided.

[0066] A pair of sprockets 65 are provided at both axial end sides 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.

[0067] In the fixing device 15 , the recording medium P is conveyed while being clamped by the heating roller 52 and the fixing cylinder 50 at the fixing position NP, and the recording medium P is heated and pressurized, thereby fixing the toner image transferred onto the recording medium P onto the recording medium P.

[0068] <Transmission mechanism 16>

[0069] Figure 1 The transport mechanism 16 shown is a mechanism for transporting the recording medium P. Figure 1 and Figure 2 As shown, the conveying mechanism 16 has a pair of chains 66 and a clamp 60. Figure 1 1 shows one of a pair of chains 66, and the chain 66 and the clamp 60 are shown in a simplified manner.

[0070] like Figure 1 As shown, a pair of chains 66 are formed into a ring shape. Figure 2 As shown, the pair of chains 66 are arranged at intervals in the depth direction (direction D in the figure). The pair of chains 66 are respectively wound around each of a pair of sprockets 64 provided at both ends of the transfer cylinder 40 in the axial direction and a pair of sprockets 65 provided at both ends of the fixing cylinder 50 in the axial direction (refer to FIG. Figure 1 ) Each of the transfer cylinder 40 and the pair of sprockets 64 are integrally driven to rotate in the rotation direction B (arrow B direction), whereby the chain 66 is rotated in the rotation direction C (arrow C direction).

[0071] like Figure 2 As shown, the mounting member 63 to which the clamper 60 is mounted is straddled along the depth direction on the pair of chains 66. A plurality of mounting members 63 are fixed to the pair of chains 66 at predetermined intervals along the circumferential direction C of the chains 66.

[0072] like Figure 2As shown in FIG. 1 , a plurality of clamps 60 are mounted on the mounting member 63 at predetermined intervals along the depth direction. The clamps 60 hold the front end of the recording medium P. Specifically, as shown in FIG. Figure 3 As shown, the clamper 60 includes a claw 61 and a claw frame 62. The clamper 60 is configured to hold the recording medium P by clamping the front end of the recording medium P between the claw 61 and the claw frame 62. In the clamper 60, the claw 61 is pressed against the claw frame 62 by a spring, for example, and the claw 61 is opened and closed relative to the claw frame 62 by a cam or the like.

[0073] In the transmission mechanism 16, as Figure 3 As shown, the front end of the recording medium P fed from the storage portion (not shown) containing the recording medium P is held by the clamper 60. The clamper 60 holding the front end of the recording medium P is rotated in the rotation direction C by the chain 66, and the recording medium P is conveyed and passed through the secondary transfer position T2 and the fixing position NP. Then, the toner image of each color that is superimposed on the transfer belt 30 at the primary transfer position T1 is secondarily transferred to the recording medium P at the secondary transfer position T2. ​​The toner image secondarily transferred to the recording medium P is fixed on the recording medium P at the fixing position NP.

[0074] In addition, the clamper 60 is accommodated together with the mounting member 63 in the recess 41 formed on the outer peripheral surface of the transfer cylinder 40 when passing through the secondary transfer position T2, and is accommodated together with the mounting member 63 in the recess 51 formed on the outer peripheral surface of the fixing cylinder 50 when passing through the fixing position NP.

[0075] <Function and Effect of the Present Embodiment>

[0076] In the transfer device 13 of this embodiment, as Figure 5 As shown, the secondary transfer roller 34 transfers the toner image onto the recording medium P wound around the transfer cylinder 40 while repeatedly colliding with and separating from the transfer sleeve 44 of the transfer cylinder 40. In the image forming apparatus 10, the toner image transferred onto the recording medium P is fixed by the fixing device 15.

[0077] Here, in the transfer device 13 , the secondary transfer roller 34 collides with the other end portion 72 of the transfer sleeve 44 as it retreats from the concave portion 41 , and sandwiches the transfer belt 30 and the recording medium P with the transfer sleeve 44 .

[0078] like Figure 2 and Figure 5As shown, when the secondary transfer roller 34 collides with the other end 72 of the transfer sleeve 44, the secondary transfer roller 34 collides sequentially starting from the portion on the reference line M closest to the upstream end 41A of the concave portion 41 in the other end 72. After colliding with the portion, the secondary transfer roller 34 rotates relatively toward the one end 70 side of the transfer sleeve 44 rotating in the B direction together with the transfer cylinder 40 along the triangular shape of the other end 72 while sandwiching the transfer belt 30 and the recording medium P, and transfers the toner image to the recording medium P. The contact length of the outer peripheral surface 44A of the transfer sleeve 44 and the transfer belt 30 and the recording medium P pressed by the secondary transfer roller 34 gradually increases in the triangular portion as the transfer cylinder 40 rotates in the B direction, so the load from the transfer sleeve 44 to the secondary transfer roller 34 gradually increases.

[0079] Furthermore, in the transfer device 13 of this embodiment, when the transfer cylinder 40 is Figure 5 When the secondary transfer roller 34 reaches Figure 6 status.

[0080] Specifically, refer to Figure 2 and Figure 6 , while the secondary transfer roller 34 is pressing the transfer belt 30 and the recording medium P onto the transfer sleeve 44, the transfer cylinder 40 rotates in the direction B until the secondary transfer roller 34 presses the side ends 70A and 70B of the transfer sleeve 44. The one end 70 including the side ends 70A and 70B is in a triangular shape, so as the transfer cylinder 40 rotates in the direction B, the contact length with the outer peripheral surface 44A of the transfer sleeve 44 decreases from this position toward the downstream end 41B of the recess 41. That is, the load from the transfer sleeve 44 to the secondary transfer roller 34 gradually decreases. Thereafter, as the secondary transfer roller 34 passes through the recess 41, the secondary transfer roller 34 separates from the transfer sleeve 44, and the secondary transfer roller 34 detaches from the downstream end 41B of the recess 41.

[0081] According to the transfer device 13 of this embodiment, the load variation of the transfer belt 30 is suppressed compared with a structure in which the two end portions (one end portion 70 and the other end portion 72) of the transfer sleeve 44 are parallel to the axis of the secondary transfer roller 34, that is, a structure in which the collision or separation of the secondary transfer roller 34 occurs simultaneously in the entire axial direction of the transfer sleeve 44.

[0082] In the transfer device 13 of this embodiment, as Figure 2 As shown, the transfer sleeve 44 is symmetrical with reference line M as the center, and the secondary transfer roller 34 starts to collide with the portion on reference line M in the other end 72 of the transfer sleeve 44, and starts to detach from the recessed portion 41 from the portion on reference line M in the one end 70. Therefore, compared with the asymmetrical structure of the transfer sleeve, the transfer belt 30 that rotates with the transfer cylinder 40 is suppressed from tilting in the axial direction.

[0083] In the transfer device 13 of this embodiment, one end 70 or the other end 72 of the transfer sleeve 44 extends toward the reference line M from both sides in the depth direction toward the recess 41. Therefore, compared with a structure in which one end of the transfer sleeve 44 extends toward multiple points, processing of one end becomes easier.

[0084] In the transfer device 13 of the present embodiment, one end 70 and the other end 72 of the transfer sleeve 44 are not parallel to the axis of the secondary transfer roller 34. Therefore, compared with a structure in which only one end is not parallel to the axis of the secondary transfer roller 34, both the collision and separation of the secondary transfer roller 34 and the transfer sleeve 44 suppress the load variation of the transfer belt 30.

[0085] In the transfer device 13 of this embodiment, the transfer sleeve 44 is replaceably mounted on the tube body 42 , so that the specifications of the end portion (one end portion 70 or the other end portion 72 ) of the transfer sleeve 44 can be easily changed compared to the case where the transfer sleeve 44 is fixed to the tube body 42 .

[0086] Furthermore, since the image forming apparatus 10 of this embodiment includes the transfer device 13 of this embodiment, disturbance of the image formed on the recording medium P caused by repeated collision and separation between the secondary transfer roller 34 and the transfer sleeve 44 as the secondary transfer roller 34 passes through the concave portion 41 is suppressed.

[0087] <Second embodiment>

[0088] The structure of an image forming apparatus 10 according to another embodiment of the present invention (hereinafter referred to as "second embodiment") will be described. The basic structure of the second embodiment is the same as that of this embodiment, and description of the same structure will be omitted.

[0089] Figure 7 The image forming apparatus 10 shown in the present embodiment is provided with covers 74 and 76 in the exposed area of ​​the base layer of the transfer sleeve 44. The covers 74 and 76 cover the portion between the one end 70 or the other end 72 of the transfer sleeve 44 and the recess 41. The covers 74 and 76 are examples of covering portions.

[0090] The covers 74 and 76 are formed in a triangular shape and have a lower elastic modulus than the transfer sleeve 44. In addition, the covers 74 and 76 have a thickness equivalent to that of the transfer sleeve 44, but the covers 74 and 76 may also be conical. The cover 74 covers two exposed areas of the base layer of the transfer sleeve 44 between one end 70 of the transfer sleeve 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 sleeve 44 and the upstream end 41A of the recess 41. The cover 74 and the cover 76 have the same size and shape.

[0091] <Operation and Effect of Second Embodiment>

[0092] In the transfer device 13 of the second embodiment, when the secondary transfer roller 34 collides with the other end 72, the secondary transfer roller 34 collides with the portion of the other end 72 on the reference line M closest to the upstream end 41A of the recessed portion 41 and the portion on the upstream end 41A side of the cover 76. Furthermore, when the secondary transfer roller 34 separates from the one end 70, the pressing force of the secondary transfer roller 34 is received by the cover 74. Therefore, compared with the structure of the present embodiment, the degradation of the one end 70 and the other end 72 of the transfer sleeve 44 is suppressed.

[0093] <Modification>

[0094] In the image forming device 10 involved in the present embodiment, the shapes of one end 70 and the other end 72 of the transfer sleeve 44 are the same triangular shape, but are not limited to this. The shapes of the one end 70 and the other end 72 may also be different triangular shapes. Specifically, the shape of the one end 70 may be a right-angled isosceles triangle, and the shape of the other end 72 may be an obtuse-angled isosceles triangle. These shapes are preferably set separately based on the image forming area, for example. In this case, compared with the structure in which the shapes of the two ends of the transfer sleeve 44 are the same, the load variation is suppressed according to the shapes of the one end 70 and the other end 72. In addition, a triangular shape may be formed in either the one end 70 or the other end 72. Moreover, the one end 70 and the other end 72 are not limited to the shapes extending in a straight line from the two side ends toward the reference line M, and may also be arc-shaped or wavy.

[0095] Hereinafter, a modification example of the one end portion 70 of the transfer sleeve 44 will be described, but the modification example can also be applied to the other end portion 72. Figure 8 As shown in (a), the end portion 70 of the transfer sleeve 44 is formed with a surface from the side end portion 70A and the side end portion 70B toward the reference line M, but it is not limited to this. For example, the end portion 70 may be an asymmetric triangular shape. Figure 8 As shown in (b), one end 70 of the transfer sleeve 44 may also be formed with a surface extending from the reference line M toward the side end 70A and the side end 70B. In this case, the bottom side L in the above-mentioned present embodiment corresponds to the sum of the line segment L1 and the line segment L2. The lengths 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 becomes the contact length. And, as Figure 8As shown in (c), in addition to being disposed on the reference line M, one end portion 70 of the transfer sleeve 44 may also be disposed on both side ends (70A and 70B), whereby the one end portion 70 as a whole is formed into a W-shape (triangular wave shape) when viewed from above. In this case, for example, it is preferred to respectively dispose the end portion 70E or the end portion 70D between the reference line M and the respective depth directions (left-right directions in the figure) of the side end portion 70A or the side end portion 70B in a manner symmetrical with respect to the reference line M. In addition, in this case, the bottom side L in the above-mentioned present embodiment corresponds to the sum of the line segments L1, L2, and L3. Furthermore, when viewed from above, the one end portion 70 as a whole may be a sine wave or the like. Furthermore, as shown in FIG. Figure 8 As shown in (d), one end 70 of the transfer sleeve 44 is triangular in shape, but may also be trapezoidal in shape. That is, the edges of the one end 70 and the other end 72 of the transfer sleeve 44 are not limited to the structure in which the entire depth direction is not parallel to the axis of the secondary transfer roller 34, but may also be partially non-parallel. Specifically, when a portion of the edge in the depth direction is parallel and the remaining portion is not parallel, as an example, the edge becomes a trapezoidal shape, and when the entire depth direction of the edge is not parallel, as an example, it becomes a right triangle shape (single-sided inclination) with the entire edge as the hypotenuse.

[0096] The transfer sleeve 44 includes a base layer, an elastic layer, and a surface layer (not shown) in the order of approaching the cylindrical surface 42A when the transfer sleeve 44 is wound around the cylindrical surface 42A of the cylinder body 42, and has a predetermined thickness, but is not limited thereto. For example, when the transfer sleeve 44 is wound around the cylindrical surface 42A of the cylinder body 42, one end 70 or the other end 72 may be formed into a tapered shape so that the thickness decreases as it approaches the recessed portion 41.

[0097] The present invention is not limited to the above-mentioned embodiment, and various deformations, changes and improvements can be made within the scope of the main purpose. For example, the above-mentioned deformation examples can be appropriately combined with multiple ones, and the transfer sleeve 44 can also be configured to be asymmetrical with respect to the reference line M, or cannot be replaced with respect to the tube body 42.

[0098] <Note> (1)

[0100] A transfer device comprising:

[0101] a transfer member formed in an endless belt shape and transferring a toner image;

[0102] A transfer cylinder having a cylinder body and a transfer sleeve, wherein the cylinder body has a concave portion extending in the axial direction formed on an outer peripheral surface, and the transfer sleeve is wound on the outer peripheral surface in a manner that both ends are arranged outside the concave portion; and

[0103] The transfer roller extends in the axial direction, sandwiches the transfer member with the transfer sleeve, transfers the toner image onto the recording medium wound on the transfer cylinder, and repeatedly collides with and separates from the transfer sleeve as it passes through the concave portion.

[0104] At least one of the two ends of the transfer sleeve has an edge that is not parallel to the axis of the transfer roller. (2)

[0106] The transfer device according to (1), wherein

[0107] The transfer sleeve is formed symmetrically with the center in the axial direction as a reference. (3)

[0109] The transfer device according to (2), wherein:

[0110] The one end portion of the transfer sleeve is formed into a triangular shape as it extends from both side ends in the axial direction toward the recessed portion toward the center. (4)

[0112] The transfer device according to any one of (1) to (3), wherein

[0113] Both ends of the transfer sleeve have edges which are not parallel to the axis of the transfer roller. (5)

[0115] The transfer device according to any one of (1) to (4), wherein:

[0116] The shapes of the two ends of the transfer sleeve are different. (6)

[0118] The transfer device according to any one of (1) to (5), wherein:

[0119] The transfer sleeve is replaceably mounted on the cylinder body. (7)

[0121] The transfer device according to any one of (1) to (6), comprising:

[0122] The covering portion covers a portion between at least one of the two end portions of the transfer sleeve and the recessed portion, and has an elastic modulus lower than that of the one end portion of the transfer sleeve. (8)

[0124] An image forming device comprising:

[0125] an image forming section including an image forming section for forming the toner image and a transfer device according to any one of (1) to (7); and

[0126] The fixing device fixes the image transferred onto the recording medium by the image forming unit.

[0127] According to the configuration of (1), compared with a configuration in which the axis of the transfer roller and the end of the transfer sleeve are parallel, load fluctuation of the transfer member is suppressed.

[0128] According to the configuration of (2), compared with a configuration in which the transfer sleeve is asymmetrical, the transfer member is prevented from tilting in the axial direction as the transfer cylinder rotates.

[0129] According to the structure of (3), compared with a structure in which one end portion of the transfer sleeve extends toward a plurality of points, processing of the one end portion becomes simple.

[0130] According to the configuration of (4), compared with a configuration in which only one end portion is not parallel to the axis of the transfer roller, both the collision and separation of the transfer roller and the transfer sleeve suppress the load fluctuation of the transfer member.

[0131] According to the configuration of (5), load fluctuations are suppressed according to the shapes of the respective ends, compared to a configuration in which both ends of the transfer sleeve have the same shape.

[0132] According to the configuration of (6), it is easier to change the specifications of the end portion of the transfer sleeve than in the case where the transfer sleeve is fixed to the tube body.

[0133] According to the structure of (7), compared with a structure in which the end of the transfer sleeve is exposed to the outer peripheral surface of the cylinder member in a state not parallel to the axis of the transfer roller, deterioration of the end is suppressed.

[0134] According to the configuration of (8), disturbance of the image formed on the recording medium caused by repeated collision and separation of the transfer roller with the transfer sleeve as the transfer roller passes through the concave portion is suppressed.

[0135] The above-mentioned embodiments of the present invention are provided for the purpose of illustration and description. In addition, the embodiments of the present invention do not fully and exhaustively include the present invention, and do not limit the present invention to the disclosed methods. Obviously, various modifications and changes are self-evident to those skilled in the art to which the present invention belongs. The present embodiment is selected and described in order to most easily understand the principles of the present invention and its application. Thus, other technicians in the art can understand the present invention through various variations optimized for specific uses assumed to be various embodiments. The scope of the present invention is defined by the above claims and their equivalents.

Claims

1. A transfer device comprising: a transfer member formed in an endless belt shape and transferring a toner image; A transfer cylinder having a cylinder body and a transfer sleeve, wherein the cylinder body has a concave portion extending in the axial direction formed on an outer peripheral surface, and the transfer sleeve is wound on the outer peripheral surface in a manner that both ends are arranged outside the concave portion; and The transfer roller extends in the axial direction, sandwiches the transfer member with the transfer sleeve, transfers the toner image onto the recording medium wound on the transfer cylinder, and repeatedly collides with and separates from the transfer sleeve as it passes through the concave portion. At least one of the two ends of the transfer sleeve has an edge that is not parallel to the axis of the transfer roller.

2. The transfer device according to claim 1, wherein: The transfer sleeve is formed symmetrically with the center in the axial direction as a reference.

3. The transfer device according to claim 2, wherein: The one end portion of the transfer sleeve is formed into a triangular shape as it extends from both side ends in the axial direction toward the recessed portion toward the center.

4. The transfer device according to any one of claims 1 to 3, wherein: Both ends of the transfer sleeve have edges which are not parallel to the axis of the transfer roller.

5. The transfer device according to any one of claims 1 to 4, wherein: The shapes of the two ends of the transfer sleeve are different.

6. The transfer device according to any one of claims 1 to 5, wherein: The transfer sleeve is replaceably mounted on the cylinder body.

7. The transfer device according to any one of claims 1 to 6, comprising: The covering portion covers a portion between at least one of the two end portions of the transfer sleeve and the recessed portion, and has an elastic modulus lower than that of the one end portion of the transfer sleeve.

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

Images