Transfer system and image forming system

Abstract

A transfer system includes: a transfer belt that is endless and sequentially transfers an image held on a plurality of image holding bodies; a winding roller on which the transfer belt is wound and which rotates by being driven by the wound transfer belt; a drive roller around which the transfer belt is wound, the drive roller being disposed on the downstream side of the winding roller and on the upstream side of a portion where an image is transferred to the transfer belt in the winding direction of the transfer belt, the drive roller applying a drive force to the transfer belt and causing the transfer belt to wind; a transfer cylinder that is disposed on the opposite side of the transfer belt from the winding roller, and that transfers the image on the transfer belt onto a conveyed recording medium while being rotationally driven; and a braking part which is arranged on the downstream side of the winding roller and the upstream side of the driving roller in the winding direction of the transfer belt, and is in contact with the back surface of the wound transfer belt to apply a braking force to the transfer belt.

Description

Technical Field

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

[0002] The image forming device described in Patent Document 1 includes a plurality of rollers for tensioning an intermediate transfer belt, a driving source for rotationally driving the intermediate transfer belt, and a component for applying torque to the rollers. When a recording medium enters a secondary transfer section composed of one of the tensioning rollers and an opposing roller opposing one of the tensioning rollers with the intermediate transfer belt interposed therebetween, the torque applied by the component for applying torque to the rollers is corrected to suppress load variations generated in the intermediate transfer belt.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2008-040289

[0004] A transfer system is provided, which comprises: an endless transfer belt, to which images held on a plurality of image holders are sequentially transferred; a driving roller, which applies driving force to the transfer belt to cause the transfer belt to revolve; a winding roller, which is driven by the transfer belt and rotates; and a transfer cylinder, which is arranged on the opposite side of the winding roller across the transfer belt and transfers the images transferred to the transfer belt to a recording medium while rotating. The images held on the plurality of image holders are sequentially transferred to the portion of the transfer belt between the driving roller and the winding roller in the revolving direction of the transfer belt.

[0005] In this transfer system, the friction force generated between the transfer cylinder and the transfer belt varies due to various factors. Due to the variation of the friction force, the tension generated in the portion of the transfer belt between the winding roller and the driving roller in the winding direction of the transfer belt varies. In addition, due to the variation of the transfer belt tension, the winding speed of the transfer belt varies, resulting in image deviation in the images transferred from the plurality of image holders to the transfer belt. Summary of the invention

[0006] The object of the present invention is to suppress image deviation generated in images transferred from multiple image holders to the transfer belt, compared to a situation in which the back side of the transfer belt on the downstream side of the winding roller and the upstream side of the driving roller in the winding direction of the transfer belt is free, as compared to a situation in which the transfer belt is wound around by the driving force of a driving roller and a transfer drum is rotated to transfer the image on the transfer belt to a recording medium.

[0007] The transfer system involved in the first embodiment of the present invention is characterized in that it comprises: a transfer belt, which is annular and sequentially transfers and retains images on multiple image retaining bodies; a winding roller, which is wound around the transfer belt and rotates driven by the rotating transfer belt; a driving roller, which is wound around the transfer belt and is arranged on the downstream side of the winding roller and the upstream side of the portion where the image is transferred to the transfer belt in the winding direction of the transfer belt, and applies driving force to the transfer belt to cause the transfer belt to rotate; a transfer cylinder, which is arranged on the side opposite to the winding roller across the transfer belt, and transfers the image on the transfer belt to the conveyed recording medium while rotating; and a braking part, which is arranged on the downstream side of the winding roller and the upstream side of the driving roller in the winding direction of the transfer belt, and contacts with the back side of the rotating transfer belt to apply braking force to the transfer belt.

[0008] The transfer system according to the second aspect of the present invention is characterized in that, in the transfer system according to the first aspect, the braking section comprises: a brake roller around which the transfer belt is wound and which is driven to rotate by the circulating transfer belt; and an imparting section which imparts a braking force to the brake roller.

[0009] A transfer system according to a third aspect of the present invention is characterized in that, in the transfer system according to the first aspect, a clamp member is provided which is arranged on the side opposite to the brake roller across the transfer belt.

[0010] A transfer system according to a fourth aspect of the present invention is the transfer system according to the third aspect, wherein the clamp member is a clamp roller that rotates following the transfer belt.

[0011] The transfer system involved in the 5th aspect of the present invention is characterized in that, in the transfer system described in any one of the 1st to 4th aspects, it comprises: a detection unit that detects the torque generated in the drive roller; and at least one processor that controls the braking unit in a manner that makes the torque generated in the drive roller fall within a threshold value based on the detection result of the detection unit.

[0012] The transfer system according to the sixth aspect of the present invention is characterized in that, in the transfer system described in the fourth aspect, the braking unit includes: a braking roller around which the transfer belt is wound; and an applying unit that applies a braking force to the braking roller, and the processor controls the applying unit.

[0013] The transfer system involved in the 7th mode of the present invention is characterized in that, in the transfer system described in any one of the 1st to 6th modes, a scraping component for scraping off attachments attached to the transfer belt is arranged on the downstream side of the winding roller and the upstream side of the braking part in the winding direction of the transfer belt.

[0014] An image forming system according to an eighth aspect of the present invention is characterized by comprising: the transfer system according to any one of the first to seventh aspects; and a fixing device that fixes the image transferred to the recording medium on the recording medium.

[0015] Effects of the Invention

[0016] According to the transfer system involved in the first embodiment of the present invention, compared with a structure in which a transfer drum is rotated and driven to transfer the image on the transfer belt to a recording medium while the transfer belt is wound by the driving force of a driving roller and the back side of the transfer belt on the downstream side of the winding roller and the upstream side of the driving roller in the winding direction of the transfer belt is not obstructed, it is possible to suppress image deviation generated in the images transferred from a plurality of image holders to the transfer belt.

[0017] According to the transfer system according to the second aspect of the present invention, it is possible to suppress abrasion of the transfer belt compared to the case where a non-rotatable braking portion is used.

[0018] According to the transfer system according to the third aspect of the present invention, the braking force of the brake roller can be effectively transmitted to the transfer belt, compared with a case where the transfer belt floats with respect to the brake roller.

[0019] According to the transfer system according to the fourth aspect of the present invention, it is possible to suppress abrasion of the transfer belt compared to the case where a non-rotatable clamp member is used.

[0020] According to the transfer system according to the fifth aspect of the present invention, the braking portion can be controlled with a simple configuration, compared with a case where the braking portion is controlled by detecting the tension generated in the transfer belt.

[0021] According to the transfer system according to the sixth aspect of the present invention, it is possible to easily make the torque generated in the driving roller fall within the threshold value, compared with the case where a non-rotatable braking portion is used.

[0022] According to the transfer system involved in the seventh embodiment of the present invention, compared with a situation in which a change in the tension of the transfer belt caused by the friction force between the scraping member and the transfer belt is directly transmitted to the transfer belt of the portion of the transfer image, thereby causing a change in the circumferential speed of the transfer belt. This makes it possible to suppress image deviation caused in images transferred from a plurality of image holders to the transfer belt.

[0023] The image forming system according to the eighth aspect of the present invention can suppress degradation in the quality of an output image compared to a transfer system in which a change in tension generated in the transfer belt is directly transmitted to a portion of the transfer belt where an image is transferred, thereby causing a change in the rotation speed of the transfer belt. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Embodiments of the present invention will be described in detail with reference to the following drawings.

[0025] Figure 1 is a schematic structural diagram showing an image forming apparatus according to an embodiment of the present invention;

[0026] Figure 2 is a schematic structural diagram showing a toner image forming unit of an image forming apparatus according to an embodiment of the present invention;

[0027] Figure 3 is a perspective view showing a chain gripper of an image forming apparatus according to an embodiment of the present invention;

[0028] Figure 4 is a perspective view showing a secondary transfer roller and the like of a transfer device according to an embodiment of the present invention;

[0029] Figure 5 is a perspective view showing a heating roller, a pressure roller, etc. of an image forming apparatus according to an embodiment of the present invention;

[0030] Figure 6 is a cross-sectional view showing a heating roller, a pressure roller, etc. of an image forming apparatus according to an embodiment of the present invention;

[0031] Figure 7 is a front view showing a transfer device according to an embodiment of the present invention;

[0032] Figure 8 middle, Figure 8 (A) Figure 8 (B) is a diagram showing a hardware configuration and a functional configuration of a control unit provided in the transfer device according to an embodiment of the present invention;

[0033] Fig. 9 is a flowchart showing a process of controlling the winding speed of a transfer belt in a transfer device according to an embodiment of the present invention;

[0034] Fig.10 middle, Fig.10 (A) Fig.10 (B) is a front view of the transfer device according to the embodiment of the present invention, showing a state where an image is transferred to a sheet member and a state where the image is not transferred;

[0035] Fig.11 It is a front view showing a transfer device according to a comparative embodiment with respect to the embodiment of the present invention.

[0036] Explanation of symbols

[0037] 10-image forming device (an example of an image forming system), 21-image holding body, 30-transfer device (an example of a transfer system), 31-transfer belt, 32a-roller (an example of a winding roller), 32b-roller (an example of a driving roller), 32d-roller (an example of a brake roller), 36-transfer cylinder, 38-scraping component, 48-clamping roller (an example of a clamping roller), 52-imparting unit, 54-detection unit, 60-braking unit, 90-control unit, 91-CPU (an example of a processor), 100-fixing device. DETAILED DESCRIPTION

[0038] according to Figures 1 to 11 An example of a transfer device and an image forming device according to an embodiment of the present invention is described. In addition, arrow H shown in the figure indicates the vertical direction of the device, arrow W indicates the width direction of the device (horizontal direction), and arrow D indicates the depth direction of the device (horizontal direction).

[0039] <Image Forming Apparatus 10 >

[0040] The image forming apparatus 10 according to the present embodiment is an electrophotographic image forming apparatus that forms a toner image on a sheet member P as a recording medium. Figure 1 As shown, the image forming apparatus 10 includes a storage unit 50, an image forming unit 12, and a control unit 18 for controlling each unit. The image forming apparatus 10 is an example of an image forming system.

[0041] (Accommodating portion 50)

[0042] The accommodating portion 50 has a function of accommodating the sheet member P. Figure 1 As shown, the storage section 50 includes a loading section 78 on which the sheet members P are loaded, and a delivery roller 58 that delivers the uppermost sheet member P loaded on the loading section 78 to the supply path 40 .

[0043] (Image Forming Unit 12)

[0044] The image forming unit 12 has a function of forming an image on the sheet member P by electrophotography. Figure 1 As shown, the image forming unit 12 is arranged above the housing unit 50. The image forming unit 12 includes a toner image forming unit 20 for forming a toner image, a transfer device 30 for transferring the toner image formed by the toner image forming unit 20 onto a sheet member P, and a fixing device 100 for fixing the toner image onto the sheet member P.

[0045] [Toner Image Forming Unit 20]

[0046] like Figure 1As shown, a plurality of toner image forming units 20 are provided to form toner images for each color. The image forming unit 12 includes toner image forming units 20 for four colors, namely yellow (Y), magenta (M), cyan (C), and black (K). Figure 1 The Y, M, C, and K shown here represent components corresponding to the above-mentioned colors.

[0047] The toner image forming section 20Y, the toner image forming section 20M, the toner image forming section 20C, and the toner image forming section 20K have basically the same configuration except for the toner used.

[0048] like Figure 1 As shown, the toner image forming units 20Y, 20M, 20C, and 20K are arranged along a horizontal portion of a transfer belt 31 provided in the transfer device 30. In the following description, when the toner image forming units 20Y, 20M, 20C, and 20K are not particularly distinguished, the last letters are omitted.

[0049] like Figure 2 As shown in the figure, the toner image forming unit 20 includes a photosensitive body, that is, an image holding body 21 that rotates in the direction of arrow A01 in the figure, and a charger 22 that charges the image holding body 21. In addition, the toner image forming unit 20 includes an exposure device 23 that forms an electrostatic latent image by exposing the image holding body 21 charged by the charger 22, and a developing device 24 that develops the electrostatic latent image with a toner to form a toner image.

[0050] [Transfer device 30]

[0051] The transfer device 30 has the following functions: to overlap the toner images of the image holding bodies 21 of the respective colors on the intermediate transfer body for primary transfer, and to perform secondary transfer of the overlapped toner images onto the sheet member P. Specifically, Figure 1 As shown, the transfer device 30 includes a transfer belt 31 as an intermediate transfer body, a plurality of rollers 32 , a primary transfer roller 33 , a transfer cylinder 36 as a secondary transfer roller, and a scraping member 38 .

[0052] The transfer belt 31 is annular and is wound around a plurality of rollers 32 in an inverted triangle shape. The toner image forming units 20Y, 20M, 20C, and 20K are arranged along the upper horizontal portion of the transfer belt 31. The transfer belt 31 is wound in the direction of arrow B by rotating at least one of the plurality of rollers 32.

[0053] In the following description, among the plurality of rollers 32, the roller 32 arranged so as to push out the inclined portion on one side (left side in the figure) in the device width direction of the transfer belt 31 is referred to as a roller 32a, and the roller 32 on which the portion on one side in the device width direction of the horizontal portion of the transfer belt 31 is wound is referred to as a roller 32b. In addition, the roller 32 arranged on the upstream side of the roller 32a in the winding direction of the transfer belt 31 is referred to as a roller 32c, and the roller 32 arranged between the roller 32a and the roller 32b in the winding direction of the transfer belt 31 is referred to as a roller 32d.

[0054] The primary transfer roller 33 is disposed on the opposite side of the image holder 21 of each color across the transfer belt 31. The primary transfer roller 33 has a function of transferring the toner image formed on the image holder 21 to the transfer belt 31 at the primary transfer position T between the image holder 21 and the primary transfer roller 33.

[0055] The transfer cylinder 36 is disposed on the opposite side of the roller 32a across the transfer belt 31. The transfer cylinder 36 has a function of transferring the toner image transferred to the transfer belt 31 onto the sheet member P at a secondary transfer position NT between the transfer belt 31 and the transfer cylinder 36.

[0056] Furthermore, a scraping member 38 is disposed between the roller 32 a and the roller 32 d in the circling direction of the transfer belt 31 , and has a function of scraping off the attached matter attached to the surface of the transfer belt 31 from the transfer belt 31 .

[0057] [Fixing device 100]

[0058] The fixing device 100 has a function of fixing, on the sheet member P, the toner image transferred onto the sheet member P by the transfer device 30 .

[0059] like Figure 1 As shown, the fixing device 100 includes a chain gripper 66 and a main heating unit 120 that comes into contact with the sheet member P and heats the toner image.

[0060] -Chain Clamp 66-

[0061] like Figure 1 As shown, the chain gripper 66 includes a pair of chains 72 , a front end holding portion 68 that holds the front end of the sheet member P, and sprockets 71 , 73 , 82 , 84 , and 86 .

[0062] like Figure 3 As shown, a pair of chains 72 are arranged separately in the depth direction of the device, and the chains 72 are formed into a ring shape. Figure 4As shown, a pair of chains 72 are wound around a pair of sprockets 73 arranged at both ends of the axial direction of the transfer cylinder 36 and with the axial direction as the depth direction of the device. In addition, the pair of chains 72 are wound around a pair of sprockets 71 arranged at one end and the other end of the axial direction of the pressure roller 140 described later and with the axial direction as the depth direction of the device (see Figure 5 ) On. Furthermore, the pair of chains 72 are wound around a pair of sprockets 82, a pair of sprockets 84, and a pair of sprockets 86 which are arranged at intervals in the depth direction of the device.

[0063] And, if Figure 1 As shown, the sprockets 71 disposed at both ends of the pressure roller 140 are disposed on one side (left side in the figure) and above the sprockets 73 disposed at both ends of the transfer cylinder 36 in the device width direction.

[0064] Furthermore, when viewed from the device depth direction, the pair of sprockets 82 are arranged on the lower side relative to the sprocket 71. Furthermore, the pair of sprockets 86 are arranged on the lower side relative to the sprockets 73 and 82, on one side in the device width direction relative to the sprocket 73, and on the other side in the device width direction relative to the sprocket 82. Furthermore, the pair of sprockets 84 are arranged so as to lift the portion of the chain 72 between the sprockets 82 and 86 from the lower side to the upper side.

[0065] like Figure 3 As shown, the front end holding portion 68 includes a mounting member 75 extending in the device depth direction and a clamp 76 mounted on the mounting member 75 , and portions on both sides of the front end holding portion 68 in the device depth direction are respectively mounted to a pair of chains 72 .

[0066] A plurality of front end holding portions 68 are provided, and are arranged at predetermined intervals along the circumferential direction (circling direction) of the chain 72 (see Figure 1 ).

[0067] A plurality of clamps 76 are provided, which are mounted on the mounting member 75 at predetermined intervals along the depth direction of the device. The clamp 76 has a function of holding the front end of the sheet member P. Specifically, the clamp 76 has a claw 76a. In addition, a contact portion 75a (see FIG. 1 ) that contacts the claw 76a is formed on the mounting member 75. Figure 6 ).

[0068] The clamper 76 is configured to hold the sheet member P by sandwiching the front end of the sheet member P between the claw 76a and the contact portion 75a. In the clamper 76, for example, the claw 76a is pressed against the contact portion 75a by a spring or the like, and the claw 76a contacts or separates from the contact portion 75a by the action of a cam or the like.

[0069] In this structure, the rotational force is transmitted to Figure 1The sprockets 71 and 73 among the plurality of sprockets 71 , 73 , 82 , 84 , 86 shown in the figure, and thereby a pair of chains 72 are wound in the direction of arrow C in the figure.

[0070] Furthermore, when the front end holding portion 68 mounted on the pair of chains 72 reaches the sprocket 73, the clamp 76 of the front end holding portion 68 clamps the front end of the sheet member P conveyed along the supply path 40, thereby holding and receiving the sheet member P. Then, the chain 72 that is circling in the direction of arrow C conveys the sheet member P held by the front end holding portion 68 toward the secondary transfer position NT. In addition, the circling chain 72 conveys the sheet member P toward the main heating portion 120. And, at the position where the front end of the sheet member P passes through the main heating portion 120, the front end holding portion 68 releases the front end holding of the sheet member P, and the chain clamp 66 delivers the sheet member P to the discharge path 42. Then, the sheet member P delivered to the discharge path 42 is discharged to the outside of the device body 10a.

[0071] -Main heating section 120-

[0072] like Figure 1 As shown in FIG. 1 , the main heating section 120 is arranged downstream of the secondary transfer position NT in the sheet conveying direction. Figure 5 As shown, the main heating unit 120 includes a heating roller 130 that contacts the conveyed sheet member P to heat the sheet member P, and a pressure roller 140 that presses the sheet member P toward the heating roller 130 .

[0073] The heating roller 130 is arranged to contact the upward surface of the conveyed sheet member P and to extend in the depth direction of the device with the axial direction as the depth direction of the device. In addition, in the depth direction of the device, shaft portions 139a extending in the depth direction of the device are formed at both ends of the heating roller 130, and support members 139b are provided to support the shaft portions 139a.

[0074] The pressure roller 140 is arranged to contact the downward surface of the conveyed sheet member P on the opposite side of the heating roller 130 across the conveyed sheet member P, and extends in the depth direction of the device with the axial direction as the depth direction of the device. Figure 6 As shown, a recess 140a extending in the depth direction of the device is formed on the outer peripheral surface of the pressure roller 140. When the sheet member P passes between the pressure roller 140 and the heating roller 130, the front end holding portion 68 that holds the front end of the sheet member P is accommodated in the recess 140a.

[0075] And, if Figure 5 As shown, a pair of shaft portions 148 are formed at both ends of the pressure roller 140 in the depth direction of the device, have a diameter smaller than that of the pressure roller 140 , and extend in the axial direction.

[0076] The main heating unit 120 includes a support member 156 for supporting the pressure roller 140 and a pressing member 158 for pressing the pressure roller 140 toward the heating roller 130 via the support member 156. A pair of support members 156 is provided. The pair of support members 156 are respectively configured to rotatably support a pair of shaft portions 148 of the pressure roller 140 from below.

[0077] In this structure, a pair of pressing members 158 press the pressure roller 140 toward the heating roller 130, whereby the pressure roller 140 presses the sheet member P toward the heating roller 130. Then, the pressure roller 140 is rotated by receiving a rotational force from a driving member (not shown). Then, the heating roller 130 is rotated by the rotating pressure roller 140. Then, the sheet member P to which the toner image is transferred is sandwiched between the heating roller 130 and the pressure roller 140 and conveyed, so that the toner image is heated and fixed on the sheet member P.

[0078] (Function of Image Forming Apparatus)

[0079] exist Figure 1 In the image forming apparatus 10 shown in FIG. 1 , a toner image is formed on a sheet member P in the following manner. First, Figure 2 The chargers 22 of each color shown uniformly charge the surface of the image holder 21 of each color negatively at a predetermined potential. Next, the exposure device 23 irradiates the charged surface of the image holder 21 of each color with exposure light according to image data input from the outside to form an electrostatic latent image.

[0080] Thus, an electrostatic latent image corresponding to the image data is formed on the surface of each image holder 21. Then, the developing device 24 of each color develops the electrostatic latent image and visualizes it as a toner image. Figure 1 The primary transfer rollers 33 of the transfer device 30 shown in the figure sequentially transfer the toner images formed on the surfaces of the image holding bodies 21 of the respective colors onto the transfer belt 31 at the primary transfer positions T.

[0081] Therefore, the sheet member P sent out from the storage portion 50 to the supply path 40 by the send-out roller 58 is handed over and conveyed to the leading end holding portion 68 of the chain gripper 66 (refer to Figure 3 The sheet member P conveyed by the chain gripper 66 is sent toward the secondary transfer position NT. At the secondary transfer position NT, the sheet member P is sandwiched and conveyed by the transfer belt 31 and the transfer cylinder 36, whereby the toner image on the surface of the transfer belt 31 is transferred to the surface of the sheet member P.

[0082] Then, the fixing device 100 fixes the toner image transferred onto the surface of the sheet member P on the sheet member P, and the sheet member P conveyed by the chain gripper 66 is sent out to the discharge path 42. The sheet member P sent out to the discharge path 42 is discharged to the outside of the apparatus body 10a.

[0083] (Main structure)

[0084] Next, the transfer device 30 will be described. The transfer device 30 is an example of a transfer system.

[0085] like Figure 1 As shown, the transfer device 30 includes a transfer belt 31, a plurality of rollers 32, a primary transfer roller 33, a transfer cylinder 36, a scraping member 38, and a control unit 90 (see Figure 8 ). The transfer device 30 is an example of a transfer system.

[0086] [Roller 32]

[0087] like Figure 7 As shown in FIG. 1 , the roller 32c disposed on the upstream side of the roller 32a in the circling direction of the transfer belt 31 functions as a tension-applying roller that applies tension to the transfer belt 31 by pressing the transfer belt 31 from the back side of the transfer belt 31. The roller 32b also functions as a driving roller that is rotationally driven by receiving a driving force from the driving source 34. In addition, a detection unit 54 (detection unit) is provided that detects a torque generated in the roller 32b based on the power supplied to the driving source 34. Figure 8 (A)).

[0088] The roller 32d is arranged between the roller 32a and the roller 32b in the winding direction of the transfer belt 31, presses the transfer belt 31 from the back side of the transfer belt 31 so that the transfer belt 31 protrudes outward, and rotates driven by the winding transfer belt 31. A powder brake (powder brake) or an imparting portion 52 is provided on the shaft of the roller 32d to impart a braking force to the roller 32d, and the roller 32d functions as a brake roller. The roller 32a is an example of a winding roller, the roller 32b is an example of a driving roller, and the roller 32d is an example of a brake roller.

[0089] The applying portion 52 and the roller 32d constitute a braking portion 60. In this embodiment, the braking portion 60 is a member that contacts the back surface of the transfer belt 31 and applies braking force to the transfer belt 31, and does not include a scraping member 38 described later.

[0090] Furthermore, a nip roller 48 is provided on the opposite side to the roller 32d across the transfer belt 31 so as to sandwich the transfer belt 31 between the roller 32d and the transfer belt 31. The nip roller 48 is an example of a pinch roller.

[0091] [Transfer cylinder 36]

[0092] like Figure 7 As shown, the transfer cylinder 36 is disposed on the opposite side of the roller 32 a across the transfer belt 31 , and is rotated by receiving the driving force of the driving source 56 .

[0093] [Scraping member 38]

[0094] like Figure 7 As shown, the scraping member 38 is disposed between the roller 32 a and the roller 32 d in the circling direction of the transfer belt 31 , and has a function of scraping off the attached matter attached to the surface of the transfer belt 31 from the transfer belt 31 .

[0095] [Control unit 90]

[0096] -Hardware Structure of Control Unit 90-

[0097] like Figure 8 As shown in (A) of FIG. 1 , the control unit 90 includes a CPU (Central Processing Unit) 91, a ROM (Read Only Memory) 92, a RAM (Random Access Memory) 93, a memory 94, and a communication interface (I / F) 95. Each structure is connected to each other so as to be communicable via a bus 99. The CPU 91 is an example of a processor.

[0098] The CPU 91 is a central processing unit that executes various programs or controls various parts. That is, the CPU 91 reads a program from the ROM 92 or the memory 94 and executes the program using the RAM 93 as a work area. The CPU 91 controls various structures and performs various calculations according to the program stored in the ROM 92 or the memory 94.

[0099] In the present embodiment, for example, a braking program for controlling the providing unit 52 to vary the braking force of the roller 32 d based on the torque information detected by the detecting unit 54 is stored in the ROM 92 or the memory 94 .

[0100] The RAM 93 temporarily stores programs and data as a work area. The memory 94 is composed of a HDD (Hard Disk Drive) or an SSD (Solid State Drive), and stores various programs including an operating system and various data.

[0101] The communication interface 95 is an interface for communicating with the detection unit 54 and the like, and uses a standard such as Ethernet (registered trademark), FDDI, or Wi-Fi (registered trademark).

[0102] When the above-mentioned braking program is executed, the control unit 90 realizes various functions using the above-mentioned hardware resources. Next, the functional configuration of the control unit 90 for realizing various functions will be described.

[0103] - Functional structure of control unit 90 -

[0104] like Figure 8 As shown in (B), the control unit 90 includes a receiving unit 96, a derivation unit 97, and an operation unit 98. Each functional configuration is implemented by the CPU 91 reading and executing a driver program stored in the ROM 92 or the memory 94. In addition, the details of the control unit 90 will be described together with the functions described later.

[0105] (The function of the main structure)

[0106] The functions of the main components are explained. Fig. 9 The flowchart shown describes a process of transferring the toner image formed in the toner image forming section 20 to the transfer belt 31 and controlling the winding speed of the transfer belt 31 when transferring the toner image transferred to the transfer belt 31 to the sheet member P.

[0107] When the receiving unit 96 of the control unit 90 receives the instruction to start the transfer operation, the operation unit 98 operates the driving source 34 to rotate the roller 32b, thereby revolving the transfer belt 31. Furthermore, the operation unit 98 operates the driving source 56 to rotate the transfer cylinder 36 and revolve the chain 72. In this way, in step S100, the receiving unit 96 of the control unit 90 detects the torque generated in the roller 32b from the detection unit 54.

[0108] Then, in step S200, the derivation unit 97 derives the braking force acting on the roller 32d. Specifically, the braking force acting on the roller 32d is derived in such a way that the torque generated in the roller 32b is changed and the changed torque falls within the threshold value. In other words, the braking force acting on the roller 32d is derived in such a way that the tension of the transfer belt 31 between the rollers 32d and 32b is changed and the changed tension falls within the threshold value.

[0109] Then, in step S300 , the operation unit 98 controls the applying unit 52 to apply the braking force to the roller 32 d .

[0110] Then, in step S400, the receiving unit 96 receives the printing information, and if the printing job is completed, the series of operations are completed. On the other hand, if the printing job is continued, the process returns to the above-mentioned step S100, and the series of operations are executed again.

[0111] As described above, the braking force is applied to the roller 32d so that the torque of the roller 32b falls within the threshold value. In other words, the braking force is applied to the roller 32d so that the tension of the transfer belt 31 between the rollers 32d and 32b falls within the threshold value.

[0112] Here, an example of the reason why the torque generated in the roller 32b changes and the reason why the torque generated in the roller 32b falls within the threshold value are described by comparing with the transfer device 230 involved in the comparative embodiment. First, the structure of the transfer device 230 involved in the comparative embodiment is mainly described with respect to the parts that are different from the transfer device 30 of the present embodiment. Fig.11 As shown, the roller 32d is not provided in the transfer device 230.

[0113] One example of a cause of the torque generated in the roller 32b changing is that the extent of the attached matter on the surface of the transfer belt 31 may vary locally in the circling direction of the transfer belt 31. This causes the frictional force generated between the rotationally driven transfer cylinder 36 and the transfer belt 31 to change.

[0114] exist Fig.11 In the transfer device 230 according to the comparative embodiment shown in FIG. 1 , due to the change in the friction force, the portion ( Fig.11 The tension of the transfer belt 31 at the portion d5) shown in the figure changes. Due to this change, the torque generated in the roller 32b also changes. When the roller 32b is driven to rotate while the tension of the transfer belt 31 at the portion between the rollers 32a and 32b changes, the winding speed (transport amount) of the transfer belt 31 at the portion where the toner image is transferred from the image holder 21 changes. Furthermore, when the winding speed of the transfer belt 31 changes, the image transferred from the image holder 21 of each color to the transfer belt 31 shifts. So-called image shift occurs.

[0115] On the other hand, Figure 7 In the transfer device 30 of the present embodiment shown in the figure, only the portion between the roller 32a and the roller 32d ( Figure 7 The torque generated in the roller 32b is brought within the threshold value by suppressing the change in the tension of the portion of the transfer belt 31 located downstream of the roller 32d in the winding direction of the transfer belt 31. In this way, by suppressing the change in the tension, the change in the winding speed (transport amount) of the transfer belt 31 in the portion where the toner image is transferred from the image holder 21 can be suppressed. Furthermore, if the change in the winding speed of the transfer belt 31 is suppressed, the image deviation generated in the image transferred from the image holder 21 of each color to the transfer belt 31 can be suppressed.

[0116] In addition, regarding the change of the friction force generated between the rotationally driven transfer cylinder 36 and the transfer belt 31, as shown in FIG. Fig.10 (A) Fig.10 As shown in (B), for example, it occurs when the sheet member P is sandwiched or not sandwiched between the transfer drum 36 and the transfer belt 31. Furthermore, the friction force may fluctuate depending on the density of the toner image formed on the sheet member P, etc.

[0117] (Summarize)

[0118] As described above, in the transfer device 30, the roller 32d provided on the downstream side of the roller 32a and the upstream side of the roller 32b in the circling direction of the transfer belt 31 applies a braking force to the circling transfer belt 31. Thus, compared with a case where the back surface of the transfer belt 31 in the portion downstream of the roller 32a and upstream of the roller 32b in the circling direction of the transfer belt 31 is not blocked, it is possible to suppress image deviation generated in the image transferred to the transfer belt 31 from the toner image forming section 20 of each color.

[0119] Furthermore, in the transfer device 30, a braking force is applied to the roller 32d that rotates following the circulating transfer belt 31. Therefore, compared with the case of using a non-rotatable braking portion, wear of the transfer belt can be suppressed.

[0120] In the transfer device 30, a nip roller 48 is arranged on the side opposite to the roller 32d across the transfer belt 31 to sandwich the transfer belt 31. Therefore, the braking force of the roller 32d is more effectively transmitted to the transfer belt 31 than when the transfer belt floats relative to the brake roller.

[0121] In the transfer device 30, a nip roller 48 is disposed on the opposite side of the roller 32d across the transfer belt 31. The nip roller 48 sandwiches the transfer belt 31 between the roller 32d and the transfer belt 31. Therefore, the abrasion of the transfer belt 31 can be suppressed compared to the case of using a non-rotatable nip member.

[0122] In the transfer device 30, the control unit 90 controls the imparting unit 52 so that the torque generated in the roller 32d falls within the threshold value based on the torque detected by the detection unit 54. Therefore, compared with the case where the tension generated in the transfer belt is detected to control the brake unit, the imparting unit 52 can be controlled with a simple structure.

[0123] In the transfer device 30, the control unit 90 controls the applying unit 52 so that the torque generated in the roller 32d falls within the threshold value based on the torque detected by the detecting unit 54. Thus, the torque generated in the roller 32d falls within the threshold value more easily than when a non-rotatable braking member is used.

[0124] Furthermore, in the transfer device 30, a scraping member 38 for scraping off the attached matter attached to the transfer belt 31 is provided on the downstream side of the roller 32a and the upstream side of the roller 32d in the winding direction of the transfer belt 31. Thus, compared with a case where a change in the tension of the transfer belt caused by the friction between the scraping member and the transfer belt is directly transmitted to the transfer belt at a portion where the image is transferred, thereby causing a change in the winding speed of the transfer belt, it is possible to suppress image deviations that occur in the image transferred from the toner image forming unit 20 of each color to the transfer belt 31.

[0125] Furthermore, since the image forming apparatus 10 includes the transfer device 30 , it is possible to suppress a decrease in the quality of an output image compared to a case where the transfer device 230 according to the comparative embodiment is included.

[0126] In addition, although a specific embodiment of the present invention has been described in detail, the present invention is not limited to the embodiment, and various other embodiments can be adopted within the scope of the present invention, which is obvious to those skilled in the art. For example, in the above-mentioned embodiment, the braking force is applied to the transfer belt 31 using the rotating roller 32d, but the braking force can also be applied to the transfer belt 31 using a non-rotating braking member. In this case, the effect exerted by using the roller 32d will not be exerted.

[0127] Furthermore, in the above embodiment, the transfer belt 31 is sandwiched between the pinch roller 48 and the roller 32d using the pinch roller 48, but the pinch roller 48 may not be used. In this case, the effect achieved by using the pinch roller 48 is not achieved.

[0128] Furthermore, in the above-described embodiment, the control unit 90 controls the imparting unit 52 so that the torque generated in the roller 32b falls within the threshold value based on the torque detected by the detection unit 54, but the braking unit may be controlled based on a pre-stored braking condition. However, in this case, the effect of controlling the imparting unit 52 based on the torque detected by the detection unit 54 is not exerted. (1)

[0130] A transfer system comprising:

[0131] The transfer belt is annular and sequentially transfers the images held on the plurality of image holding bodies;

[0132] A winding roller, on which the transfer belt is wound, and which is driven by the circulating transfer belt to rotate;

[0133] a driving roller around which the transfer belt is wound, arranged on the downstream side of the winding roller and on the upstream side of a portion of the transfer belt where the image is transferred, in the winding direction of the transfer belt, and applying a driving force to the transfer belt to cause the transfer belt to wind;

[0134] a transfer cylinder disposed on the opposite side of the transfer belt from the winding roller, and rotatingly driving the transfer belt to transfer the image on the transfer belt to the conveyed recording medium; and

[0135] The brake portion is disposed on the downstream side of the winding roller and the upstream side of the driving roller in the winding direction of the transfer belt, and contacts the back surface of the winding transfer belt to apply a braking force to the transfer belt. (2)

[0137] The transfer system according to (1), wherein:

[0138] The braking section includes: a braking roller around which the transfer belt is wound and which is driven by the circulating transfer belt to rotate; and an applying section which applies a braking force to the braking roller. (3)

[0140] The transfer system according to (1) includes a clamp member disposed on the opposite side of the transfer belt from the brake roller. (4)

[0142] The transfer system according to (3), wherein:

[0143] The clamp member is a clamp roller that rotates following the transfer belt. (5)

[0145] The transfer system according to any one of (1) to (4), comprising:

[0146] a detection unit that detects a torque generated in the driving roller; and

[0147] at least one processor,

[0148] The processor controls the braking unit in accordance with a detection result of the detection unit so that the torque generated in the driving roller falls within a threshold value. (6)

[0150] The transfer system according to (4), wherein:

[0151] The braking unit includes: a braking roller around which the transfer belt is wound; and an imparting unit that imparts a braking force to the braking roller.

[0152] The processor controls the granting unit. (7)

[0154] The transfer system according to any one of (1) to (6), wherein

[0155] A scraping member for scraping off attached matter attached to the transfer belt is arranged on the downstream side of the winding roller and the upstream side of the braking portion in the circling direction of the transfer belt. (8)

[0157] An image forming system comprising:

[0158] The transfer system according to any one of (1) to (7); and

[0159] The fixing device fixes the image transferred to the recording medium on the recording medium.

[0160] According to the transfer system involved in (1), compared with a structure in which a transfer drum is rotated and driven while the transfer belt is wound by the driving force of a driving roller and transfers the image on the transfer belt to a recording medium, and the back side of the transfer belt on the downstream side of the winding roller and the upstream side of the driving roller in the winding direction of the transfer belt is not obstructed, it is possible to suppress image deviation generated in the image transferred from a plurality of image holders to the transfer belt.

[0161] According to the transfer system according to (2), compared with the case where a non-rotatable braking portion is used, wear of the transfer belt can be suppressed.

[0162] According to the transfer system according to (3), compared with a case where the transfer belt floats relative to the brake roller, the braking force of the brake roller can be effectively transmitted to the transfer belt.

[0163] According to the transfer system according to (4), compared with the case where a non-rotatable clamp member is used, wear of the transfer belt can be suppressed.

[0164] According to the transfer system according to (5), the braking portion can be controlled with a simple structure, compared with a case where the braking portion is controlled by detecting the tension generated in the transfer belt.

[0165] According to the transfer system according to (6), compared with the case where a non-rotatable braking portion is used, it is easier to make the torque generated in the driving roller fall within the threshold value.

[0166] According to the transfer system involved in (7), compared with a situation in which a change in the tension of the transfer belt caused by the friction between the scraping component and the transfer belt is directly transmitted to the transfer belt of the portion of the transfer image, thereby causing a change in the circulatory speed of the transfer belt, it is possible to suppress image deviation caused in images transferred from multiple image holders to the transfer belt.

[0167] According to the image forming system of (8), it is possible to suppress a decrease in the quality of an output image, compared with a transfer system in which a change in tension generated in the transfer belt is directly transmitted to a portion of the transfer belt where an image is transferred, thereby causing a change in the rotation speed of the transfer belt.

[0168] 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 system comprising: The transfer belt is annular and sequentially transfers the images held on the plurality of image holding bodies; A winding roller, on which the transfer belt is wound, and which is driven by the circulating transfer belt to rotate; a driving roller, around which the transfer belt is wound, arranged on the downstream side of the winding roller and on the upstream side of a portion of the transfer belt where the image is transferred, in the winding direction of the transfer belt, and applying a driving force to the transfer belt to cause the transfer belt to wind; A transfer cylinder is arranged on the side opposite to the winding roller across the transfer belt, and is driven to transfer the image on the transfer belt to the conveyed recording medium while being rotated; and The brake portion is disposed on the downstream side of the winding roller and the upstream side of the driving roller in the winding direction of the transfer belt, and contacts the back surface of the winding transfer belt to apply a braking force to the transfer belt.

2. The transfer system according to claim 1, wherein: The braking section includes: a braking roller around which the transfer belt is wound and which is driven by the circulating transfer belt to rotate; and an applying section which applies a braking force to the braking roller. 3 . The transfer system according to claim 1 , further comprising a clamp member disposed on the side opposite to the brake roller across the transfer belt.

4. The transfer system according to claim 3, wherein: The clamp member is a clamp roller that rotates following the transfer belt.

5. The transfer system according to any one of claims 1 to 4, comprising: a detection unit that detects a torque generated in the driving roller; and at least one processor, The processor controls the braking unit in accordance with a detection result of the detection unit so that the torque generated in the driving roller falls within a threshold value.

6. The transfer system according to claim 4, wherein: The braking unit includes: a braking roller around which the transfer belt is wound; and an imparting unit that imparts a braking force to the braking roller. The processor controls the providing unit.

7. The transfer system according to any one of claims 1 to 6, wherein: A scraping member for scraping off attached matter attached to the transfer belt is arranged on the downstream side of the winding roller and the upstream side of the braking portion in the circling direction of the transfer belt.

8. An image forming system comprising: The transfer system according to any one of claims 1 to 7; and The fixing device fixes the image transferred to the recording medium on the recording medium.

Images