Image forming apparatus

Abstract

To reduce driving force that a drive mechanism should generate in order to oscillate an oscillation roll provided with a flywheel in comparison to a case where a direction of the driving force applied to an application object part by the drive mechanism is the same as a direction in which the application object part moves due to gravity acting on the flywheel.SOLUTION: An image formation apparatus comprises: a formation object body 52 which is conveyed; an image formation body which forms an image on the formation object body; a change roll 45 which is in contact with the inner peripheral surface of the formation object body in a manner of being rotatable around a rotational shaft and can change an angle with respect to a width direction of the formation object body of the rotational shaft; a flywheel which is provided in the change roll; and a drive mechanism 70 which applies driving force for changing the angle with respect to the width direction of the rotational shaft to an application object part 65 that moves together with the change roll. A direction of the driving force applied to the application object part by the drive mechanism is the reverse of a direction in which the application object part moves due to gravity acting on the flywheel.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to an image forming apparatus.

Background Art

[0002] The image forming apparatus of Patent Document 1 includes an image carrier, a latent image forming device that forms a latent image on the image carrier, a developing device that develops the latent image, an endless intermediate transfer belt that travels in proximity to a part of the image carrier, a first transfer device that transfers the visible image on the developed image carrier to the intermediate image carrier belt, a recording medium transport device that transports a recording medium, a second transfer device that transfers the image on the intermediate image carrier belt to the recording medium, and a fixing device that fixes the image on the recording medium. The image forming apparatus is an electrophotographic image forming apparatus, wherein the intermediate image carrier belt is stretched between a driving roller and a driven roller, and a rotational inertia control means is connected to the rotation axis of the driven roller.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to reduce the driving force that the driving mechanism must generate to swing a swing roll provided with a flywheel, compared with the case where the direction of the driving force applied by the driving mechanism to the applied part is the same as the direction in which the applied part moves due to the gravity acting on the flywheel.

Means for Solving the Problems

[0005] In order to achieve the above object, an image forming apparatus according to a first aspect of the present invention includes a workpiece to be conveyed, an image forming member that forms an image on the workpiece, a changing roll that is rotatably in contact with the inner peripheral surface of the workpiece around a rotation axis and can change an angle of the rotation axis with respect to the width direction of the workpiece, a flywheel provided on the changing roll, and a drive mechanism that applies a driving force for changing an angle of the rotation axis with respect to the width direction to a portion to which the driving force is applied and that moves together with the changing roll. A direction of the driving force applied by the drive mechanism to the portion to which the driving force is applied is opposite to a direction in which the portion to which the driving force is applied moves due to gravity acting on the flywheel.

[0006] An image forming apparatus according to a second aspect of the present invention is the image forming apparatus according to the first aspect, and includes a housing that houses the workpiece, the image forming member, the changing roll, the portion to which the driving force is applied, the flywheel, and the drive mechanism, and that is provided with an opening that is opened and closed by an opening / closing member on a front surface. The flywheel is provided at a front end portion of the changing roll that is relatively movable in a front-rear direction with respect to the workpiece, the image forming member, and the drive mechanism.

[0007] Further, an image forming apparatus according to a third aspect of the present invention is the image forming apparatus according to the second aspect, and the drive mechanism applies the driving force to the portion to which the driving force is applied and that moves together with a rear end portion of the changing roll. The changing roll is rotatable around a rotation center axis that intersects the rotation axis.

[0008] Further, an image forming apparatus according to a fourth aspect of the present invention is the image forming apparatus according to any one of the first to third aspects, and the drive mechanism includes an electric motor having a rotation output shaft and a cam member fixed to the rotation output shaft. The portion to which the driving force is applied is a cam follower with which the cam member is rotatably in contact.

[0009] Moreover, the image forming apparatus according to the fifth aspect of the present invention is the image forming apparatus according to the fourth aspect, wherein the changing roll is rotatable about a rotation center axis provided so as to intersect the rotation axis, the flywheel is provided at one end in the longitudinal direction of the changing roll, the cam follower is located on the other end side in the longitudinal direction rather than the middle part in the longitudinal direction of the changing roll, and the direction of the driving force applied by the cam member to the cam follower is opposite to the direction in which the cam follower moves due to the gravity acting on the flywheel.

Advantages of the Invention

[0010] According to the first aspect, compared with the case where the direction of the driving force applied by the drive mechanism to the driven part is the same as the direction in which the driven part moves due to the gravity acting on the flywheel, the drive force that the drive mechanism has to generate in order to change the angle of the rotation axis of the changing roll provided with the flywheel with respect to the width direction of the object to be formed can be reduced.

[0011] According to the second aspect, even when a part of the flywheel is located on the outer peripheral side of the object to be formed when viewed in the front-rear direction, the changing roll and the flywheel can be moved forward of the housing through an opening provided in the front surface of the housing.

[0012] According to the third aspect, compared with the case where the flywheel and the driven part are provided at the front end or the rear end of the changing roll, it becomes easier to change the angle of the rotation axis of the changing roll with respect to the width direction of the object to be formed. Further, even when a part of the drive mechanism is located on the outer peripheral side of the changing roll rather than the object to be formed when viewed in the front-rear direction, the changing roll and the flywheel can be moved forward of the housing through an opening provided in the front surface of the housing.

[0013] According to the fourth aspect, the driving force applied by the cam member to the cam follower can reduce the driving force that the electric motor has to generate in order to change the angle of the rotation axis of the modified roll provided with the flywheel with respect to the width direction of the object to be formed, as compared with the case where the direction of the driving force applied by the cam member to the cam follower is the same as the direction in which the applied portion moves due to the gravity acting on the flywheel.

[0014] According to the fifth aspect, the driving force applied by the cam member to the cam follower can reduce the driving force that the electric motor has to generate in order to change the angle of the rotation axis of the modified roll provided with the flywheel with respect to the width direction of the object to be formed, as compared with the case where the direction of the driving force applied by the cam member to the cam follower is the same as the direction in which the applied portion moves due to the gravity acting on the flywheel.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. In the following, the upstream side in the conveyance direction of the recording paper P as an example of the recording medium may be simply referred to as the "upstream side", and the downstream side in the conveyance direction may be simply referred to as the "downstream side". Similarly, the upstream side in the circumferential direction (conveyance direction) of the transfer belt (belt) (object to be formed) 52 may be simply referred to as the "upstream side", and the downstream side in the circumferential direction (conveyance direction) may be simply referred to as the "downstream side". Note that the reference positions of the "upstream side" and "downstream side" of the transfer belt in the following description are the secondary transfer position T2 (nip region Np) shown in FIG. 4. That is, the direction from the secondary transfer position T2 through the drive roll 44 and then toward the push roll 49 is the "downstream side" of the transfer belt, and the direction from the secondary transfer position T2 through the driven roll 47 and then toward the second photoreceptor unit 30K is the "upstream side" of the transfer belt.

[0017] As shown in FIGS. 1 and 4, the image forming apparatus 10 of the present embodiment is an electrophotographic method for forming a toner image (an example of an image) on the recording paper P. The image forming apparatus 10 includes a housing 11, an image forming unit 12, a storage unit 14, a conveyance unit 16, and a fixing device 18. Hereinafter, each part of the image forming apparatus 10 will be described.

[0018] In the following description, the width direction (horizontal direction) of the housing 11 is defined as the X direction, the vertical direction (vertical direction) of the housing 11 is defined as the Y direction, and the front-rear direction (the direction orthogonal to the paper surface of FIG. 1) orthogonal to the X direction and the Y direction is defined as the Z direction. In FIG. 1, the front side of the paper surface is the front, and the back side of the paper surface is the back.

[0019] <Housing> As shown in FIG. 1, an opening 11A is formed in the front surface of a housing 11 having a substantially rectangular parallelepiped shape. The housing 11 includes an opening / closing member 11B capable of opening and closing the opening 11A. An image forming unit 12, a storage unit 14, a conveyance unit 16, and a fixing device 18 are provided in the internal space of the housing 11. The first photoreceptor unit 20, the second photoreceptor unit 30, and the transfer device 50 (integrated unit 50X), which will be described later, are movable between the internal space of the housing 11 and the front space of the housing 11 through the opening 11A.

[0020] <Image forming unit> The image forming unit 12 has a function of forming a toner image on a recording paper P. The image forming unit 12 includes a first photoreceptor unit 20, a second photoreceptor unit 30, and a transfer device 50.

[0021] [Photoreceptor unit] As shown in FIG. 1, two first photoreceptor units 20 and two second photoreceptor units 30 are provided. Each first photoreceptor unit 20 and each second photoreceptor unit 30 are detachable from the apparatus main body. The image forming apparatus 10 includes first photoreceptor units 20Y and 20M for yellow (Y) and magenta (M), and second photoreceptor units 30C and 30K for cyan (C) and black (K).

[0022] In the following description, when it is necessary to distinguish each color of yellow (Y), magenta (M), cyan (C), and black (K), an English letter of Y, M, C, or K is appended after the reference numeral of each member. When it is not necessary to distinguish each color, the English letters of Y, M, C, and K may be omitted.

[0023] The transfer belt 52 composed of an elastic material of the transfer device 50 described below has two straight portions that form a straight line when viewed from the Z direction. These two straight portions are the upper portion 52A and the lower portion 52B. When viewed from the Z direction, the upper portion 52A is along the X direction, and the lower portion 52B is inclined with respect to the X direction. That is, when viewed from the Z direction, the angle θB (see FIG. 4) formed by the lower portion 52B and the X direction is an acute angle, and the angle θB is larger than the angle θA (not shown) formed by the upper portion 52A and the X direction. Note that the angle θA is 0° or an acute angle slightly larger than 0°. When viewed from the Z direction, the upper portion 52A and the lower portion 52B are arranged side by side in the Y direction. The width direction of the transfer belt 52 is along the Z direction.

[0024] The two first photoreceptor units 20 face the outer peripheral surface (upper surface) of the upper portion 52A and are arranged in the X direction along the upper portion 52A. Each first photoreceptor unit 20 has a first photoreceptor drum 22 that rotates in one direction (for example, the counterclockwise direction in FIG. 4). Each first photoreceptor drum 22 is rotatable around a rotation axis 20X extending in the Z direction. Further, each first photoreceptor unit 20 has, in order from the upstream side in the rotation direction of the first photoreceptor drum 22, a first charging portion 24, a first exposure portion 25, a first developing portion 26, and a first removing portion 27. Furthermore, each first photoreceptor unit 20 has a pair of support plates 28 spaced apart from each other in the Z direction. Note that in FIG. 4, the illustration of one of the support plates 28 is omitted. The first charging portion 24, the first exposure portion 25, the first developing portion 26, and the first removing portion 27 are members extending in the Z direction. Both ends in the Z direction of the first charging portion 24, the first exposure portion 25, the first developing portion 26, and the first removing portion 27 are respectively supported by the pair of support plates 28. Further, the relative movement of the pair of support plates 28 is restricted.

[0025] The two second photoreceptor units 30 face the outer peripheral surface (lower surface) of the lower portion 52B and are arranged along the lower portion 52B. Each second photoreceptor unit 30 has a second photoreceptor drum 32 that rotates in one direction (for example, the counterclockwise direction in FIG. 4). Each second photoreceptor drum 32 is rotatable about a rotation axis 30X extending in the Z direction. Also, each second photoreceptor unit 30 has, in order from the upstream side in the rotation direction of the second photoreceptor drum 32, a second charging portion 34, a second exposure portion 35, a second developing portion 36, and a second removing portion 37. Further, each second photoreceptor unit 30 has a pair of second support plates 38 spaced apart from each other in the Z direction. Note that in FIG. 4, the illustration of one of the second support plates 38 is omitted. The second charging portion 34, the second exposure portion 35, the second developing portion 36, and the second removing portion 37 are members extending in the Z direction. Both end portions in the Z direction of the second charging portion 34, the second exposure portion 35, the second developing portion 36, and the second removing portion 37 are respectively supported by the pair of second support plates 38. Further, the relative movement of the pair of second support plates 38 is restricted.

[0026] In this specification and the claims, the "image forming body" refers to something that attaches toner or ink to the object to be formed (for example, the transfer belt 52). That is, the first photoreceptor drum 22 of the first photoreceptor unit 20 corresponds to the "image forming body", and the second photoreceptor drum 32 of the second photoreceptor unit 30 corresponds to the "image forming body". That is, the first charging portion 24, the first exposure portion 25, the first developing portion 26, and the first removing portion 27 do not correspond to the "image forming body". Similarly, the second charging portion 34, the second exposure portion 35, the second developing portion 36, and the second removing portion 37 do not correspond to the "image forming body". Note that as will be described later, when the image forming apparatus 10 is of the inkjet type, the inkjet head corresponds to the "image forming body".

[0027] The first charging unit 24 of each first photoreceptor unit 20 charges the outer peripheral surface of the first photoreceptor drum 22. Then, the first exposure unit 25 exposes the outer peripheral surface of the first photoreceptor drum 22 charged by the first charging unit 24 to form an electrostatic latent image on the outer peripheral surface of the first photoreceptor drum 22. Also, the first developing unit 26 develops the electrostatic latent image formed on the outer peripheral surface of the first photoreceptor drum 22 by the first exposure unit 25 to form a toner image. Then, after the transfer of the toner image to the transfer belt 52, the first removing unit 27 removes the toner remaining on the outer peripheral surface of the first photoreceptor drum 22.

[0028] The second charging unit 34 of each second photoreceptor unit 30 charges the outer peripheral surface of the second photoreceptor drum 32. Then, the second exposure unit 35 exposes the outer peripheral surface of the second photoreceptor drum 32 charged by the second charging unit 34 to form an electrostatic latent image on the outer peripheral surface of the second photoreceptor drum 32. Also, the second developing unit 36 develops the electrostatic latent image formed on the outer peripheral surface of the second photoreceptor drum 32 by the second exposure unit 35 to form a toner image. Then, after the transfer of the toner image to the transfer belt 52, the second removing unit 37 removes the toner remaining on the outer peripheral surface of the second photoreceptor drum 32.

[0029] [Transfer Device] As shown in FIGS. 2 to 4, the transfer device 50 includes a front base member 50A, a rear base member 50B, four primary transfer rolls 41 that are primary transfer members, a drive roll 44, a steering roll (changing roll) 45, a backup roll 46, a transfer belt 52 that is a transfer member, a flywheel 55, a driven mechanism 60, a drive mechanism 70, and a transfer cylinder 85 that is a secondary transfer member. That is, the transfer device 50 superposes and primary transfers the toner image formed on the outer peripheral surface of each first photoreceptor drum 22 onto the transfer belt 52, and secondary transfers the superposed toner image onto the recording paper P.

[0030] (Front Base Member, Rear Base Member) As shown in FIGS. 2 and 3, the transfer device 50 includes a front base member 50A and a rear base member 50B. When viewed in the axial direction of the first photoreceptor unit 20 and the second photoreceptor unit 30, the shapes of the front base member 50A and the rear base member 50B are substantially triangular. However, when viewed in the axial direction, the right end portion 50B1 of the rear base member 50B is located to the right of the right end portion of the front base member 50A. Since the front base member 50A and the rear base member 50B are connected by a connecting member (not shown), the front base member 50A and the rear base member 50B are not relatively movable.

[0031] (Primary transfer roll) Both end portions of each primary transfer roll 41 facing the upper portion 52A and each primary transfer roll 41 facing the lower portion 52B are rotatably supported by the front base member 50A and the rear base member 50B. As shown in FIG. 4, each primary transfer roll 41 facing the upper portion 52A transfers the toner image formed on the outer peripheral surface of each first photoreceptor drum 22 to the outer peripheral surface of the transfer belt 52 at the primary transfer position T1 between the first photoreceptor drum 22 and the primary transfer roll 41. Each primary transfer roll 41 facing the lower portion 52B transfers the toner image formed on the outer peripheral surface of each second photoreceptor drum 32 to the outer peripheral surface of the transfer belt 52 at the primary transfer position T1 between the second photoreceptor drum 32 and the primary transfer roll 41. In the present embodiment, a primary transfer voltage is applied between the primary transfer roll 41 and the first photoreceptor drum 22, whereby the toner image formed on the outer peripheral surface of the first photoreceptor drum 22 is transferred to the outer peripheral surface of the transfer belt 52 at the primary transfer position T1. Similarly, a primary transfer voltage is applied between the primary transfer roll 41 and the second photoreceptor drum 32, whereby the toner image formed on the outer peripheral surface of the second photoreceptor drum 32 is transferred to the outer peripheral surface of the transfer belt 52 at the primary transfer position T1.

[0032] (Driven roll) The four driven rolls 39, 40, 47, and 48 are rotatably supported at both their ends by the front base member 50A and the rear base member 50B. Note that the driving roll 44, backup roll 46, and pushing roll 49, which will be described later, are also rotatably supported at both their ends by the front base member 50A and the rear base member 50B.

[0033] The driven roll 39 is located downstream of the first photoreceptor unit 20Y and upstream of the steering roll 45. The driven roll 40 is located upstream of the second photoreceptor unit 30C and downstream of the steering roll 45. The driven roll 47 is located downstream of the second photoreceptor unit 30K and upstream of the backup roll 46. The driven roll 48 is located upstream of the first photoreceptor unit 20Y and downstream of the driving roll 44.

[0034] (Transfer Belt) The annular transfer belt 52 is wound around the four driven rolls 39, 40, 47, 48, the driving roll 44, the steering roll 45, the backup roll 46, and the pushing roll 49, and its posture is determined.

[0035] The driving roll 44 with a circular cross-section is configured to be rotationally driven about an axis 44X extending in the Z direction by a driving unit (not shown), and to circulate the transfer belt 52 in a circulation direction indicated by arrow A in FIG. 4 at a predetermined speed.

[0036] The steering roll 45 with a circular cross-section shown in FIGS. 4 and 5 is rotatable about a rotation axis 45X extending along one direction. The steering roll 45 is an example of a changing roll.

[0037] (Flywheel) A disk-shaped flywheel 55 is fixed to the front end portion 45F (see FIG. 3) of the steering roll 45 so as to be coaxial with the steering roll 45. The diameter of the flywheel 55 is larger than the diameter of the steering roll 45.

[0038] (Driven mechanism) As shown in FIGS. 6 to 8, the driven mechanism 60 is attached to the right end portion 50B1 of the rear base member 50B. The driven mechanism 60 includes a moving member 61, a rear bearing 62, a tension spring 63, a supported member 64, and a cam follower 65.

[0039] A rectangular through-hole 50B2 having an up-and-down dimension longer than the left-and-right dimension is formed in the right end portion 50B1. Immediately before the right end portion 50B1, a moving member 61 is provided. The up-and-down dimension of the moving member 61 is smaller than that of the through-hole 50B2, and the left-and-right dimension of the moving member 61 is larger than that of the through-hole 50B2. When viewed along the rotation axis 45X, the left edge portion of the moving member 61 is located on the left side of the through-hole 50B2 and the right edge portion of the moving member 61 is located on the right side of the through-hole 50B2. On both the left and right sides of the upper end portion of the moving member 61, a pair of supported portions 61A are formed.

[0040] The upper ends of a pair of tension springs 63 are respectively supported by a pair of protrusions 50B3 provided on the upper portion of the front surface of the right end portion 50B1. Further, the lower ends of the respective tension springs 63 are connected to the left and right supported portions 61A of the moving member 61. By connecting the supported portion 61A to the tension spring 63, the left and right tension springs 63 are in a state of being stretched from the free state. That is, the left and right tension springs 63 always generate a biasing force for moving the moving member 61 upward.

[0041] A circular hole 61B is formed in the central portion of the moving member 61. The diameter of the circular hole 61B is larger than the diameter of the steering roll 45. Further, a rear bearing 62 coaxial with the circular hole 61B is rotatably supported in the circular hole 61B via a bearing (not shown).

[0042] A supported member 64 is provided immediately behind the right end portion 50B1. As shown in FIG. 6, the supported member 64 has a base portion 64A and protruding pieces 64B provided at four locations on the base portion 64A. The cross-sectional shape of the base portion 64A is substantially U-shaped. The base portion 64A has a main body portion 64A1 that is substantially orthogonal to the Z direction and forms a substantially rectangle, and a pair of side portions 64A2 that extend forward from the left and right side edges of the main body portion 64A1. A circular hole 64A3 is formed in the main body portion 64A1. The circular hole 64A3 has a larger diameter than the steering roll 45. The vertical dimension of the supported member 64 is smaller than that of the through hole 50B2, and the horizontal dimension of the supported member 64 is larger than that of the through hole 50B2. However, the horizontal dimension of the main body portion 64A1 is smaller than that of the through hole 50B2. When viewed along the rotation axis 45X, the left side edges of the two left protruding pieces 64B are located to the left of the through hole 50B2, and the right side edges of the two right protruding pieces 64B are located to the right of the through hole 50B2. At the front surface of each protruding piece 64B, the rear end portion of a connection pin 64C that extends forward from the protruding piece 64B and penetrates the through hole 50B2 is fixed. The front end portion of each connection pin 64C is fixed to the moving member 61. In this way, the moving member 61 and the supported member 64 are connected to each other by the four connection pins 64C. Further, the two right connection pins 64C face the right side surface of the through hole 50B2, and the two left connection pins 64C face the left side surface of the through hole 50B2. Further, when the moving member 61 and the supported member 64 are connected to each other, the circular hole 61B of the moving member 61, the rear bearing 62, and the circular hole 64A3 of the supported member 64 are coaxial with each other.

[0043] On the rear surface of the main body portion 64A1, a cam follower 65 located above the circular hole 64A3 is rotatably supported via a rolling bearing (not shown). The axis of the cam follower 65 and the axis of the rolling bearing are along the Z direction. The outer peripheral surface of the cam follower 65 is a cylindrical surface centered on the axis of the cam follower 65.

[0044] As shown in FIG. 6, the rear end portion of a tie bar 67 extending along the Z direction is fixed to the moving member 61. A substantially C-shaped front bearing 68 is fixed to the front end portion of the tie bar 67. Further, a rotation center shaft 45AX extending leftward from the tie bar 67 is fixed to the central portion in the longitudinal direction of the tie bar 67. The rotation center shaft 45AX is rotatably inserted into a bearing member (not shown) which is a component of the transfer device 50 that is non-movable relative to the front base member 50A and the rear base member 50B. Accordingly, the tie bar 67, the moving member 61, and the front bearing 68 are relatively rotatable with respect to the bearing member about the rotation center shaft 45AX. Note that the position in the left-right direction of the tie bar 67 and the moving member 61 is determined by a roller (not shown) provided on the tie bar 67 coming into contact with a member (not shown) located on the left side of the tie bar 67.

[0045] When the opening / closing member 11B of the housing 11 opens the opening 11A, an integrated object having a steering roll 45 and a flywheel 55 located in front of the housing 11 is relatively moved rearward with respect to the housing 11, whereby the integrated object can be moved into the internal space of the housing 11. At this time, the steering roll 45 is located in a right-side space 50S (see FIGS. 5 and 6) which is a space formed between the right end portion of the front base member 50A and the right end portion of the transfer belt 52. Further, as shown in FIGS. 7 and 8, when a rear end portion 45R, which is a portion located rearward of the rear end surface of the transfer belt 52 of the steering roll 45 moved to the right-side space 50S, is inserted into the circular hole 61B, the rear bearing 62, and the circular hole 64A3 of the supported member 64, and the front portion of the steering roll 45 is moved leftward so that the front portion of the steering roll 45 is supported by the front bearing 68, the integrated object is integrated with the moving member 61, the tie bar 67, and the front bearing 68. That is, the integrated object having the steering roll 45 and the flywheel 55 becomes relatively rotatable with respect to the bearing member about the rotation center shaft 45AX.

[0046] When the rotation axis 45X is parallel to the Z direction, the position of the rotation direction SD (see Fig. 5) around the rotation center axis 45AX of the steering roll 45 is the neutral position of the steering roll 45. When the flywheel 55 fixed to the steering roll 45 mounted on the rear bearing 62 and the front bearing 68 is viewed along the rotation axis 45X in this way, as shown in Fig. 5, a part of the outer peripheral edge of the flywheel 55 is located on the outer peripheral side of the transfer belt 52 from the right end of the transfer belt (upper 52A and lower 52B). However, as shown in Figs. 2 and 3, when the integral body having the steering roll 45 and the flywheel 55 is integrated with the moving member 61, the tire 67, and the front bearing 68, the front end portion (one end portion in the longitudinal direction of the steering roll 45) 45F of the steering roll 45 and the flywheel 55 are located in front of the front end face of the transfer belt 52.

[0047] Furthermore, when the steering roll 45 and the rotation center axis 45AX integrated with the moving member 61, the tire 67, and the front bearing 68 are viewed in plan view, the rotation center axis 45AX intersects the rotation axis 45X of the steering roll 45. Furthermore, when the steering roll 45 and the rotation center axis 45AX are viewed in plan view, the extension line of the rotation center axis 45AX intersects the central portion 45M (see Fig. 6) in the direction of the rotation axis 45X of the steering roll 45. Here, assume two specific portions 45P of the steering roll 45 located on both sides of the exact central position in the longitudinal direction of the steering roll 45. The distance from the central position to the two specific portions 45P is 10% of the total length of the steering roll 45. The region between these two specific portions 45P corresponds to the "central portion 45M in the direction of the rotation axis 45X of the steering roll 45" in this specification.

[0048] (Drive mechanism) As shown in Figs. 6 to 8, the drive mechanism 70 is attached to the rear surface of the right end portion 50B1 of the rear base member 50B. The drive mechanism 70 includes a support member 71, an electric motor 72, and a cam member 73.

[0049] The support member 71 has a substantially rectangular main body portion 71A, a pair of side portions 71B extending forward from the left and right side edges of the main body portion 71A, and three fixed portions 71C extending laterally from the front end portions of the respective side portions 71B. A through hole (not shown) is formed in the main body portion 71A. The support member 71 faces the rear surface of the right end portion 50B1, and the three fixed portions 71C are in contact with the rear surface of the right end portion 50B1. Further, the fixed portions 71C and the right end portion 50B1 are fixed to each other by bolts 75 passing through the respective fixed portions 71C.

[0050] The electric motor 72 has a case 72A and a rotary output shaft 72B protruding forward from the case 72A. The case 72A is fixed to the rear surface of the main body portion 71A, and the rotary output shaft 72B passes through the through hole of the main body portion 71A forward. Further, a cam member 73 positioned immediately in front of the main body portion 71A is fixed to the front end portion of the rotary output shaft 72B. The electric motor 72 is controlled by a control device (not shown).

[0051] As shown in FIGS. 9 and 10, a part of the outer peripheral surface of the cam member 73 is constituted by a cam surface 73A having different radial distances of the rotary output shaft 72B from the rotation center (rotary output shaft 72B) of the cam member 73 according to the circumferential position. When the cam member 73 is viewed from the front along the rotary output shaft 72B, the radial distance from the rotary output shaft 72B to the cam surface 73A gradually increases as the cam surface 73A advances in the clockwise direction. For example, the radial distance RL2 between the point P2 on the cam surface 73A and the electric motor 72 is longer than the radial distance RL1 between the point P1 on the cam surface 73A and the rotary output shaft 72B.

[0052] The cam member 73 is positioned directly above the cam follower 65. As described above, the left and right tension springs 63 always generate a biasing force for moving the moving member 61 upward. Therefore, the upper end portion of the outer peripheral surface of the cam follower 65 that moves together with the moving member 61 is always in contact with the cam surface 73A of the cam member 73.

[0053] When the control device transmits a forward rotation signal (electrical signal) to the electric motor 72 while the driven mechanism 60 and the drive mechanism 70 are in the states shown in FIGS. 7 to 9, the cam member 73 rotates counterclockwise about the rotation output shaft 72B in a front view. As a result, as shown in FIG. 10, the contact position between the cam follower 65 on the cam surface 73A changes from the point P1 to the point P2 side. Then, the cam follower 65, the supported member 64, and the moving member 61 are moved downward by the cam surface 73A against the biasing force of the tension spring 63 (see the phantom line in FIG. 9 and FIG. 10). Therefore, the steering roll 45 rotates about the rotation center axis 45AX and the flywheel 55 moves upward. Further, for example, when the point P2 is in contact with the cam follower 65 and the control device transmits a reverse rotation signal (electrical signal) to the electric motor 72, the cam member 73 rotates clockwise about the rotation output shaft 72B in a front view. As a result, the contact position between the cam follower 65 on the cam surface 73A changes from the point P2 to the point P1 side. Then, due to the biasing force of the tension spring 63 and the cam surface 73A, the cam follower 65, the supported member 64, and the moving member 61 are moved upward. Therefore, the steering roll 45 rotates about the rotation center axis 45AX and the flywheel 55 moves downward.

[0054] Some of the component members of the transfer device 50 configured as described above are integrated with each other as described above. That is, the driven rolls 39, 40, 47, 48, the primary transfer roll 41, the drive roll 44, the steering roll 45, the backup roll 46, the push-in roll 49, the flywheel 55, the front base member 50A, the rear base member 50B, the transfer belt 52, the driven mechanism 60, and the drive mechanism 70 are integrated with each other. Hereinafter, the integrated unit of these members is referred to as an integrated unit 50X. When the opening / closing member 11B of the housing 11 opens the opening 11A, the integrated unit 50X located inside the housing 11 can be moved forward with respect to the housing 11, and thus the integrated unit 50X can be moved forward of the housing 11 through the opening 11A. Further, when the opening / closing member 11B of the housing 11 opens the opening 11A, the integrated unit 50X located in front of the housing 11 can be moved rearward with respect to the housing 11, and thus the integrated unit 50X can be moved into the internal space of the housing 11 through the opening 11A. That is, by using the opening 11A, the integrated unit 50X provided in the internal space of the housing 11 can be replaced with a new integrated unit 50X.

[0055] Furthermore, when the opening / closing member 11B of the housing 11 opens the opening 11A, the steering roll 45 and the flywheel 55, which are component members of the integrated unit 50X provided in the internal space of the housing 11, can be moved forward of the housing 11 in a manner of separating them from the other component members of the integrated unit 50X. That is, when the front portion of the steering roll 45 is moved to the right side, the support state of the front portion of the steering roll 45 by the front bearing 68 is released. After that, when the steering roll 45 and the flywheel 55 are moved forward, the rear end portion 45R escapes rearward from the rear bearing 62 and the circular hole 64A3 of the supported member 64. After that, when the steering roll 45 and the flywheel 55 are further moved forward, the steering roll 45 and the flywheel 55 move forward of the housing 11 through the opening 11A. That is, by using the opening 11A, the steering roll 45 and the flywheel 55 provided in the internal space of the housing 11 can be replaced with new steering roll 45 and flywheel 55.

[0056] As shown in FIG. 4, backup roll 46 faces transfer cylinder 85 with transfer belt 52 interposed therebetween. The area where transfer cylinder 85 and transfer belt 52 are in contact is nip area Np. Nip area Np is secondary transfer position T2 where the toner image is transferred from transfer belt 52 to recording paper P.

[0057] Furthermore, pressing roll 49, which is located upstream of driven roll 48 and downstream of driving roll 44, rotatably contacts the outer peripheral surface of transfer belt 52 and presses transfer belt 52 toward the inner peripheral side.

[0058] <Transport unit> As shown in FIG. 4, transport unit 16 has a transport device (not shown) that transports recording paper P sent out from storage unit 14 in the direction of arrow B. By the transport device, recording paper P sent out from storage unit 14 is transported to transfer cylinder 85. Recording paper P onto which the toner image has been secondarily transferred by passing through transfer cylinder 85 (secondary transfer position T2) is transported to fixing device 18 by the transport device.

[0059] <Fixing device> As shown in FIG. 4, fixing device 18 has heating roll 42 as an example of a heating member and pressure roll 43 as an example of a pressure member. Fixing device 18 fixes the toner image transferred to recording paper P by transfer cylinder 85 to the recording paper P by heating and pressing the recording paper P with heating roll 42 and pressure roll 43 interposed therebetween.

[0060] Next, the operation and effects of image forming apparatus 10 configured as described above will be described in detail.

[0061] In the image forming apparatus 10 of the present embodiment, when the transfer belt 52 moves (snakes) in the width direction, when a movement amount detection device (not shown) detects the movement amount (snake amount) of the transfer belt 52 in the width direction, the control device transmits at least one of a forward rotation signal and a reverse rotation signal to the electric motor 72. As a result, the steering roll 45 rotates about the rotation center axis 45AX, so that the angle of the rotation axis 45X with respect to the width direction (Z direction) of the transfer belt 52 changes. As a result, the meandering of the transfer belt 52 is suppressed by the steering roll 45.

[0062] Incidentally, as shown in FIGS. 9 and 10, the direction DF of the driving force applied by the electric motor 72 of the present embodiment to the cam follower 65 that moves together with the steering roll 45 via the cam member 73 is downward. On the other hand, the direction MD in which the cam follower 65 (steering roll 45) moves due to the gravity acting on the flywheel 55 is upward. That is, when the transfer device 50 is viewed along the Z direction, the direction DF of the driving force is opposite to the direction MD. Therefore, the contact state between the cam follower 65 and the cam member 73 is more easily maintained than when the direction DF and the direction MD are the same. Therefore, the driving force that the electric motor 72 (drive mechanism 70) must generate to change the angle of the rotation axis 45X of the steering roll 45 provided with the flywheel 55 with respect to the width direction of the transfer belt 52 can be made smaller than when the direction DF and the direction MD are the same.

[0063] Here, the "opposite direction" is a concept including the case where the direction DF and the direction MD are completely parallel and the case where the direction DF and the direction MD are slightly inclined to each other. The inclination angle formed by the direction DF and the direction MD in this case is an arbitrary magnitude of 10° or less.

[0064] Furthermore, when the flywheel 55 of the present embodiment is viewed in the Z direction, a part of the flywheel 55 is located on the outer peripheral side of the transfer belt 52. However, the flywheel 55 is located on the front side of the transfer belt 52 and the steering roll 45 is separable from the rear bearing 62 and the front bearing 68. Therefore, the steering roll 45 and the flywheel 55 can be moved forward of the housing 11 through the opening 11A provided in the front surface of the housing 11.

[0065] Furthermore, in the image forming apparatus 10 of the present embodiment, when viewed in the Z direction, a part of the drive mechanism 70 is located on the outer peripheral side of the steering roll 45 from the transfer belt 52. However, in the present embodiment, the steering roll 45 and the flywheel 55 are relatively movable in the front-rear direction with respect to the drive mechanism 70. Therefore, although a part of the drive mechanism 70 is located on the outer peripheral side of the steering roll 45 from the transfer belt 52 when viewed in the Z direction, the steering roll 45 and the flywheel 55 can be moved forward of the housing 11 through the opening 11A.

[0066] Furthermore, while the flywheel 55 is provided at the front end portion 45F of the steering roll 45, a cam follower 65 that receives the driving force generated by the electric motor 72 via the cam member 73 is located on the rear end portion side of the steering roll 45. Therefore, the image forming apparatus 10 of the present embodiment is easier to change the angle of the rotation axis 45X of the steering roll 45 with respect to the width direction of the transfer belt 52 than in the case where the flywheel 55 is provided at the front end portion 45F of the steering roll 45 and the cam follower 65 is located on the front end portion 45F side of the steering roll 45, and in the case where the flywheel 55 is provided at the rear end portion of the steering roll 45 and the cam follower 65 is located on the rear end portion side of the steering roll 45.

[0067] As described above, the image forming apparatus 10 according to the present embodiment has been described with reference to the drawings. However, the image forming apparatus 10 according to the present embodiment is not limited to the illustrated one, and can be appropriately designed and changed within the scope not departing from the gist of the present invention.

[0068] For example, the present invention may be implemented in the form of a modification shown in FIGS. 11 and 12. In this modification, a flywheel 55 is fixed to the front end portion 45F of the steering roll 45, and a driven mechanism 60 and a driving mechanism 70 are provided in the vicinity of the leading edge portion of the transfer belt 52. Further, a rotation center axis 45AX is provided in the vicinity of the rear end portion 45R of the steering roll 45. Therefore, in this modification, when the electric motor 72 of the driving mechanism 70 operates, the steering roll 45 and the flywheel 55 rotate about the rotation center axis 45AX. Further, in this modification, as shown in FIG. 12, a cam member 73 is located directly below the cam follower 65. Further, the direction DF of the driving force applied by the electric motor 72 (cam member 73) to the cam follower 65 that moves in the vertical direction together with the front end portion 45F of the steering roll 45 is upward. On the other hand, the direction MD in which the cam follower 65 (front end portion 45F of the steering roll 45) moves due to the gravity acting on the flywheel 55 is downward. That is, the direction DF of the driving force is opposite to the direction MD. Therefore, the image forming apparatus 10 of this modification can also reduce the driving force that the electric motor 72 (driving mechanism 70) must generate in order to change the angle of the rotation axis 45X of the steering roll 45 provided with the flywheel 55 with respect to the width direction of the transfer belt 52, as compared with the case where the direction DF and the direction MD are the same.

[0069] Although not shown, a flywheel 55 may be fixed to the rear end portion of the steering roll 45, and a driven mechanism 60 and a driving mechanism 70 may be provided in the vicinity of the trailing edge portion of the transfer belt 52. Further, in this case, a rotation center axis 45AX is provided in the vicinity of the front end portion 45F of the steering roll 45. Further, in this case, the cam member 73 is positioned directly below the cam follower 65. Further, the direction DF of the driving force applied by the electric motor 72 (cam member 73) to the cam follower 65 that moves vertically together with the rear end portion of the steering roll 45 is upward. On the other hand, the direction MD in which the cam follower 65 (the rear end portion of the steering roll 45) moves due to the gravity acting on the flywheel 55 is downward. The image forming apparatus 10 of this modification can also reduce the driving force that the electric motor 72 (driving mechanism 70) must generate in order to change the angle of the rotation axis 45X of the steering roll 45 provided with the flywheel 55 with respect to the width direction of the transfer belt 52, as compared with the case where the direction DF and the direction MD are the same.

[0070] A cam follower (applied portion) 65 may be fixed to the steering roll 45.

[0071] The driving mechanism may be a mode different from the above-described embodiments and each modification. For example, the driving mechanism may be a mechanism including an electric motor and a moving member that advances and retreats along the rotation output shaft of the electric motor and applies a force to the applied portion. In this case, the direction DF of the driving force applied by the moving member to the applied portion and the direction MD in which the applied portion moves due to the gravity acting on the flywheel 55 are opposite to each other.

[0072] Further, the image forming apparatus 10 may be configured such that each first photoreceptor unit 20 and each second photoreceptor unit 30 form a toner image on a recording sheet P (formed body) conveyed by a conveyance belt (not shown) provided instead of the transfer belt 52.

[0073] In addition, in this embodiment, a toner image is given as an example of an image, and here it is a toner image formed by a dry electrophotographic method, but the present invention is not limited to this. For example, the image of the present invention may be a toner image formed by a wet electrophotographic method or an image formed by an inkjet method.

[0074] Further, an ink image or a toner image is formed on a long and non-annular continuous paper (object to be formed), which is wound around a plurality of rotators including a drive roll 44 and is conveyed by the drive roll 44 and the rotators, having a shape with at least one straight portion when viewed along the Z direction, and the image forming apparatus 10 may be configured such that a steering roll (changing roll) 45 rotatably contacts the inner peripheral surface of the continuous paper.

[0075] The number of types of colors of the image (toner image, ink image) formed on the object to be formed (transfer belt 52, recording medium P) does not have to be four. For example, the number of types of colors of the image may be six.

[0076] For example, three or more image forming members may be arranged along the upper portion 52A. Similarly, three or more image forming members may be arranged along the lower portion 52B.

Explanation of Reference Numerals

[0077] 10 Image forming apparatus 11 Housing 11A Opening 11B Opening / closing member 22 First photosensitive drum (image forming member) 32 Second photosensitive drum (image forming member) 45 Steering roll (changing roll) 45AX Rotation center axis 45X Rotation axis 55 Flywheel 65 Cam follower (portion to be imparted) 70 Driving mechanism 72 Electric motor 72B Rotating output shaft 73 Cam member P Recording paper (object to be formed)

Claims

1. A workpiece to be conveyed, an image forming unit that forms an image on the workpiece, a changing roll that is rotatably in contact with the inner peripheral surface of the workpiece about its own rotation axis and can change the angle of the rotation axis with respect to the width direction of the workpiece, a flywheel provided on the changing roll, a drive mechanism that applies a driving force for changing the angle of the rotation axis with respect to the width direction to a part to which the force is applied and that moves together with the changing roll, wherein, the direction of the driving force applied by the drive mechanism to the part to which the force is applied is opposite to the direction in which the part to which the force is applied moves due to the gravity acting on the flywheel, an image forming apparatus.

2. The image forming apparatus according to claim 1, further comprising a housing that houses the workpiece, the image forming unit, the changing roll, the part to which the force is applied, the flywheel, and the drive mechanism, and that is provided with an opening at the front surface thereof which is opened and closed by an opening / closing member, wherein the flywheel is provided at a front end portion of the changing roll that is relatively movable in the front-rear direction with respect to the workpiece, the image forming unit, and the drive mechanism. The image forming apparatus according to claim 1.

3. The drive mechanism applies the driving force to the part to which the force is applied and that moves together with a rear end portion of the changing roll, wherein the changing roll is rotatable about a rotation center axis that intersects the rotation axis. The image forming apparatus according to claim 2.

4. The drive mechanism includes: an electric motor having a rotational output shaft; and a cam member fixed to the rotational output shaft. wherein, the part to which the force is applied is a cam follower with which the cam member is rotatably in contact. The image forming apparatus according to any one of claims 1 to 3.

5. The changing roll is rotatable about a rotation center axis provided so as to intersect the rotation axis, the flywheel is provided at one end portion in the longitudinal direction of the changing roll, the cam follower is located on the other end side in the longitudinal direction of the changing roll rather than in the middle portion in the longitudinal direction of the changing roll, and the direction of the driving force applied by the cam member to the cam follower is opposite to the direction in which the cam follower moves due to the gravity acting on the flywheel. The image forming apparatus according to claim 4.

Images