Transfer system and image forming system

Abstract

To suppress image deviation occurring in an image transferred to a transfer belt from a plurality of image holding bodies, when compared with the case where a rear surface of the transfer belt of a portion on the downstream side of a winding roll and on the upstream side of a drive roll is free, in a revolving direction of the transfer belt, in a constitution where the transfer belt revolves by a driving force of the drive roll and a transfer cylinder for transferring an image of the transfer belt to a recording medium rotationally drives.SOLUTION: A transfer system includes: an endless transfer belt; a winding roll around which the transfer belt is wound, and which rotates so as to follow; a drive roll around which the transfer belt is wound, and which imparts a driving force to the transfer belt and revolves the transfer belt; a transfer cylinder which is arranged on the opposite side from the winding roll sandwiching the transfer belt, and transfers the image to a recording medium to be conveyed; and a brake part which is arranged on the downstream side of the winding roll and on the upstream side of the drive roll in the revolving direction of the transfer belt, and comes into contact with a rear surface of the revolving transfer belt and imparts a brake force to the transfer belt.SELECTED DRAWING: Figure 7

Description

[Technical field]

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

[0002] The image forming device described in Patent Document 1 includes a number of rollers that tension an intermediate transfer belt, a drive source that drives and rotates the intermediate transfer belt, and a means for applying torque to the rollers. When a recording medium enters a secondary transfer section consisting of one of the tension rollers and an opposing roller across the intermediate transfer belt, the torque applied by the means for applying torque to the rollers is corrected so as to suppress load fluctuations occurring in the intermediate transfer belt. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-040289 A Summary of the Invention [Problem to be solved by the invention]

[0004] There is a transfer system that includes an endless transfer belt onto which images held on a plurality of image holders are sequentially transferred, a drive roll that applies a driving force to the transfer belt to rotate the transfer belt, a winding roll that rotates following the transfer belt, and a transfer cylinder that is disposed on the opposite side of the winding roll across the transfer belt and transfers the images transferred onto the transfer belt onto a recording medium while being driven to rotate. The images held on the plurality of image holders are sequentially transferred onto the transfer belt in the rotation direction of the transfer belt at a portion between the drive roll and the winding roll.

[0005] In such a transfer system, the frictional force generated between the transfer cylinder and the transfer belt varies due to various factors. This frictional force fluctuation causes the tension generated in the transfer belt between the winding roll and the drive roll in the rotational direction of the transfer belt to vary. This fluctuation in tension of the transfer belt causes the rotational speed of the transfer belt to vary, resulting in image misalignment of images transferred from multiple image carriers to the transfer belt.

[0006] The objective of the present disclosure is to suppress image misalignment that occurs in images transferred from multiple image carriers to the transfer belt, in a configuration in which a transfer belt rotates due to the driving force of a drive roll, and a transfer cylinder that transfers an image from the transfer belt to a recording medium is driven to rotate, compared to a case in which the back surface of the transfer belt downstream of the winding roll and upstream of the drive roll in the rotation direction of the transfer belt is free. [Means for solving the problem]

[0007] A transfer system according to a first aspect of the present disclosure is characterized in that it comprises: an endless transfer belt onto which images held on a plurality of image carriers are sequentially transferred; a winding roll around which the transfer belt is wound and which rotates in conjunction with the rotation of the transfer belt; a drive roll around which the transfer belt is wound and which is disposed downstream of the winding roll in the direction of rotation of the transfer belt and upstream of the portion where the image is transferred to the transfer belt, and which applies a driving force to the transfer belt to rotate the transfer belt; a transfer cylinder which is disposed on the opposite side of the winding roll across the transfer belt and which transfers the image on the transfer belt to a recording medium being transported while being driven in rotation; and a braking unit which is disposed downstream of the winding roll and upstream of the drive roll in the direction of rotation of the transfer belt, and which contacts the back surface of the rotating transfer belt to apply a braking force to the transfer belt.

[0008] A transfer system according to a second aspect of the present disclosure is characterized in that, in the transfer system described in the first aspect, the braking unit includes a braking roll around which the transfer belt is wound and which rotates in response to the transfer belt as it rotates, and an application unit that applies a braking force to the braking roll.

[0009] A transfer system according to a third aspect of the present disclosure is the transfer system according to the second aspect, further comprising a pinching member disposed on the opposite side of the brake roll with the transfer belt sandwiched therebetween.

[0010] A transfer system according to a fourth aspect of the present disclosure is the transfer system according to the third aspect, characterized in that the pinching member is a pinching roll that rotates in accordance with the transfer belt.

[0011] A transfer system according to a fifth aspect of the present disclosure is the transfer system described in the first aspect, further comprising a detection unit that detects a torque generated in the drive roll and at least one processor, and the processor controls the braking unit based on the detection result of the detection unit so that the torque generated in the drive roll falls within a threshold value.

[0012] A transfer system according to a sixth aspect of the present disclosure is characterized in that, in the transfer system described in the fifth aspect, the braking unit includes a braking roll wrapped around the transfer belt and an application unit that applies a braking force to the braking roll, and the processor controls the application unit.

[0013] A transfer system according to a seventh aspect of the present disclosure is characterized in that, in the transfer system described in the first aspect, a scraping member for scraping off adhesions adhering to the transfer belt is arranged downstream of the winding roll and upstream of the braking section in the rotation direction of the transfer belt.

[0014] An image forming system according to an eighth aspect of the present disclosure is characterized in that it comprises a transfer system as described in any one of claims 1 to 7, and a fixing device that fixes the image transferred to the recording medium onto the recording medium. Effect of the Invention

[0015] According to the transfer system of the first aspect of the present disclosure, the transfer belt rotates due to the driving force of the drive roll, and the transfer cylinder that transfers the image on the transfer belt to a recording medium is driven to rotate, and image misalignment that occurs in images transferred from multiple image carriers to the transfer belt can be suppressed compared to a case in which the back surface of the transfer belt downstream of the winding roll and upstream of the drive roll in the rotation direction of the transfer belt is free.

[0016] According to the transfer system according to the second aspect of the present disclosure, wear on the transfer belt can be suppressed compared to a case in which a non-rotatable braking unit is used.

[0017] According to the transfer system according to the third aspect of the present disclosure, the braking force of the brake roll can be transmitted to the transfer belt more effectively than in a case where the transfer belt floats relative to the brake roll.

[0018] According to the transfer system according to the fourth aspect of the present disclosure, wear on the transfer belt can be suppressed compared to a case in which a non-rotatable pinching member is used.

[0019] According to the transfer system according to the fifth aspect of the present disclosure, the braking unit can be controlled with a simpler configuration than when the braking unit is controlled by detecting the tension generated in the transfer belt.

[0020] According to the transfer system according to the sixth aspect of the present disclosure, the torque generated in the drive roll can be easily controlled within the threshold value, compared to a case in which a non-rotatable braking unit is used.

[0021] According to the transfer system of the seventh aspect of the present disclosure, image misalignment occurring in images transferred from multiple image carriers to the transfer belt can be suppressed, compared to a case in which fluctuations in the tension of the transfer belt caused by friction between the scraping member and the transfer belt are directly transmitted to the transfer belt in the portion where the image is transferred, causing fluctuations in the rotational speed of the transfer belt.

[0022] According to the image forming system relating to the eighth aspect of the present disclosure, deterioration in the quality of the output image can be suppressed compared to a case in which a transfer system is provided in which fluctuations in tension generated in the transfer belt are directly transmitted to the part of the transfer belt where the image is transferred, causing fluctuations in the rotational speed of the transfer belt. [Brief description of the drawings]

[0023] [Figure 1] 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present disclosure. [Diagram 2] 1 is a schematic configuration diagram illustrating a toner image forming unit of an image forming apparatus according to an embodiment of the present disclosure. [Diagram 3] FIG. 2 is a perspective view showing a chain gripper of an image forming apparatus according to an embodiment of the present disclosure. [Figure 4] FIG. 2 is a perspective view showing a secondary transfer roll and the like of a transfer device according to an embodiment of the present disclosure. [Diagram 5] FIG. 2 is a perspective view showing a heating roll, a pressure roll, and the like of the image forming apparatus according to the embodiment of the present disclosure. [Figure 6] FIG. 2 is a cross-sectional view showing a heating roll, a pressure roll, and the like of the image forming apparatus according to the embodiment of the present disclosure. [Figure 7] FIG. 2 is a front view showing a transfer device according to an embodiment of the present disclosure. [Figure 8] 5A and 5B are diagrams illustrating a hardware configuration and a functional configuration of a control unit provided in a transfer device according to an embodiment of the present disclosure. [Figure 9] FIG. 11 is a flow diagram showing a process for controlling the peripheral speed of a transfer belt in a transfer device according to an embodiment of the present disclosure. [Figure 10] 1A and 1B are front views of a transfer device according to an embodiment of the present disclosure, showing a state in which an image is being transferred to a sheet member and a state in which an image is not being transferred. [Figure 11] FIG. 11 is a front view showing a transfer device according to a comparative example to the embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] An example of a transfer device and an image forming apparatus according to an embodiment of the present invention will be described with reference to Figures 1 to 11. Note that, in the drawings, arrow H indicates the up-down direction (vertical direction) of the device, arrow W indicates the width direction (horizontal direction) of the device, and arrow D indicates the depth direction (horizontal direction) of the device.

[0025] <Image forming apparatus 10> The image forming apparatus 10 according to this embodiment is an electrophotographic image forming apparatus that forms a toner image on a sheet member P as a recording medium. As shown in Fig. 1, the image forming apparatus 10 includes a storage section 50, an image forming section 12, and a control section 18 that controls each section. The image forming apparatus 10 is an example of an image forming system.

[0026] (Storage section 50) The storage section 50 has a function of storing sheet materials P. As shown in FIG 1, the storage section 50 includes a stacking section 78 on which the sheet materials P are stacked, and a delivery roll 58 that delivers the topmost sheet material P stacked on the stacking section 78 to the supply path 40.

[0027] (Image forming unit 12) The image forming unit 12 has a function of forming an image on the sheet member P by an electrophotographic method. As shown in Fig. 1, the image forming unit 12 is disposed above the storage unit 50. The image forming unit 12 includes a toner image forming unit 20 that forms a toner image, a transfer device 30 that transfers the toner image formed in the toner image forming unit 20 to the sheet member P, and a fixing device 100 that fixes the toner image to the sheet member P.

[0028] [Toner image forming unit 20] As shown in Fig. 1, a plurality of toner image forming units 20 are provided to form toner images for each color. The image forming unit 12 is provided with toner image forming units 20 for a total of four colors: yellow (Y), magenta (M), cyan (C), and black (K). Y, M, C, and K shown in Fig. 1 indicate components corresponding to the above-mentioned colors.

[0029] The toner image forming units 20Y, 20M, 20C, and 20K are basically configured in the same manner except for the toners used.

[0030] 1, the toner image forming units 20Y, 20M, 20C, and 20K are aligned along the horizontal portion of a transfer belt 31 provided in a transfer device 30. In the following description, when there is no need to distinguish between the toner image forming units 20Y, 20M, 20C, and 20K, the alphabets at the end of the names will be omitted.

[0031] 2, the toner image forming unit 20 includes an image carrier 21, which is a photoconductor that rotates in the direction of the arrow A01 in the figure, and a charger 22 that charges the image carrier 21. The toner image forming unit 20 further includes an exposure device 23 that exposes the image carrier 21 charged by the charger 22 to form an electrostatic latent image, and a developing device 24 that develops the electrostatic latent image with toner to form a toner image.

[0032] [Transfer device 30] The transfer device 30 has a function of primarily transferring the toner images of the image carriers 21 of each color onto an intermediate transfer body in a superimposed manner, and then secondarily transferring the superimposed toner images onto a sheet member P. Specifically, as shown in FIG. 1, the transfer device 30 includes a transfer belt 31 as an intermediate transfer body, a plurality of rolls 32, a primary transfer roll 33, a transfer cylinder 36 as a secondary transfer roll, and a scraping member 38.

[0033] The transfer belt 31 is endless and wound around multiple rolls 32 so as to assume an inverted triangular posture. The toner image forming units 20Y, 20M, 20C, and 20K are aligned along the upper horizontal portion of the transfer belt 31. The transfer belt 31 rotates in the direction of arrow B when at least one of the multiple rolls 32 is driven to rotate.

[0034] In the following description, among the multiple rolls 32, the roll 32 arranged so as to push out the inclined portion of the transfer belt 31 on one side in the device width direction (the left side in the drawing) is referred to as roll 32a, and the roll 32 around which the horizontal portion of the transfer belt 31 on one side in the device width direction is wound is referred to as roll 32b. Furthermore, the roll 32 arranged upstream of the roll 32a in the rotation direction of the transfer belt 31 is referred to as roll 32c, and the roll 32 arranged between the roll 32a and the roll 32b in the rotation direction of the transfer belt 31 is referred to as roll 32d.

[0035] The primary transfer rolls 33 are disposed on the opposite side of the image carriers 21 of the respective colors across the transfer belt 31. The primary transfer rolls 33 have a function of transferring the toner images formed on the image carriers 21 to the transfer belt 31 at a primary transfer position T between the image carriers 21 and the primary transfer rolls 33.

[0036] The transfer cylinder 36 is disposed on the opposite side of the roll 32a across the transfer belt 31. The transfer cylinder 36 has a function of transferring the toner image transferred onto 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.

[0037] In addition, a scraping member 38 is disposed between the rolls 32a and 32d in the rotation direction of the transfer belt 31, and has the function of scraping off any deposits adhering to the surface of the transfer belt 31 from the transfer belt 31.

[0038] [Fixing device 100] The fixing device 100 has a function of fixing the toner image transferred onto the sheet member P by the transfer device 30 onto the sheet member P.

[0039] As shown in FIG. 1, the fixing device 100 includes a chain gripper 66 and a main heating section 120 that comes into contact with the sheet member P to heat the toner image.

[0040] -Chain Gripper 66- As shown in FIG. 1, the chain gripper 66 includes a pair of chains 72, a leading end holding portion 68 that holds the leading end of the sheet material P, and sprockets 71, 73, 82, 84, and 86.

[0041] As shown in Fig. 3, the pair of chains 72 are arranged to be spaced apart in the device depth direction, and the chains 72 are formed in an endless shape. As shown in Fig. 4, the pair of chains 72 are wound around a pair of sprockets 73 that are arranged at both axial ends of the transfer cylinder 36 and whose axial direction is the device depth direction. The pair of chains 72 are also wound around a pair of sprockets 71 (see Fig. 5) that are arranged at one end and the other end of the axial direction of the pressure roll 140 described below and whose axial direction is the device depth direction. The pair of chains 72 are also wound around a pair of sprockets 82, a pair of sprockets 84, and a pair of sprockets 86 that are arranged at an interval in the device depth direction.

[0042] In addition, as shown in FIG. 1, the sprockets 71 arranged on both ends of the pressure roll 140 are arranged on one side in the device width direction (the left side in the figure) and above the sprockets 73 arranged on both ends of the transfer cylinder 36.

[0043] Moreover, when viewed from the depth direction of the device, the pair of sprockets 82 are disposed below sprocket 71. Furthermore, the pair of sprockets 86 are disposed below sprockets 73 and 82, on one side of sprocket 73 in the width direction of the device, and on the other side of sprocket 82 in the width direction of the device. The pair of sprockets 84 are disposed so as to lift the portion of chain 72 between sprockets 82 and 86 from the lower side to the upper side.

[0044] As shown in Figure 3, the tip holding portion 68 has an attachment member 75 extending in the device depth direction and a gripper 76 attached to the attachment member 75, and both side portions of the tip holding portion 68 in the device depth direction are respectively attached to a pair of chains 72.

[0045] A plurality of tip holders 68 are provided and are arranged at predetermined intervals along the circumferential direction (circumferential direction) of the chain 72 (see FIG. 1).

[0046] A plurality of grippers 76 are provided and attached to the attachment member 75 at predetermined intervals along the device depth direction. The grippers 76 have a function of holding the leading edge of the sheet material P. Specifically, the grippers 76 have claws 76a. The attachment member 75 is also formed with contact portions 75a (see FIG. 6) with which the claws 76a come into contact.

[0047] The gripper 76 is configured to hold the sheet material P by pinching the leading end of the sheet material P between the claw 76a and the contact portion 75a. Note that, for example, the claw 76a of the gripper 76 is pressed against the contact portion 75a by a spring or the like, and the claw 76a is moved toward and away from the contact portion 75a by the action of a cam or the like.

[0048] In this configuration, when a rotational force is transmitted to sprockets 71 and 73 among a plurality of sprockets 71, 73, 82, 84, and 86 shown in FIG. 1, a pair of chains 72 rotates in the direction of arrow C in the figure.

[0049] Furthermore, when the leading end holding portion 68 attached to the pair of chains 72 reaches the sprocket 73, the gripper 76 of the leading end holding portion 68 pinches the leading end of the sheet material P transported along the supply path 40 to hold and receive the sheet material P. Then, the chain 72 revolving in the direction of the arrow C transports the sheet material P held by the leading end holding portion 68 toward the secondary transfer position NT. Furthermore, the revolving chain 72 transports the sheet material P toward the main heating unit 120. Also, at a position where the leading end of the sheet material P has passed through the main heating unit 120, the leading end holding portion 68 releases the leading end holding of the sheet material P, and the chain gripper 66 sends the sheet material P to the discharge path 42. Then, the sheet material P sent to the discharge path 42 is discharged to the outside of the device main body 10a.

[0050] -Main heating section 120- The main heating section 120 is disposed downstream of the secondary transfer position NT in the sheet conveying direction, as shown in Fig. 1. The main heating section 120 also includes a heating roll 130 that contacts the conveyed sheet member P to heat the sheet member P, and a pressure roll 140 that presses the sheet member P against the heating roll 130, as shown in Fig. 5.

[0051] The heating roll 130 is disposed so as to contact the upward surface of the sheet member P being conveyed and extend in the device depth direction with its axial direction being the device depth direction. Also, shaft portions 139a extending in the device depth direction are formed on both ends of the heating roll 130 in the device depth direction, and support members 139b are provided to support the shaft portions 139a.

[0052] The pressure roll 140 is disposed on the opposite side of the heating roll 130 with the sheet member P being conveyed sandwiched therebetween, in contact with the downward surface of the sheet member P being conveyed, and extending in the device depth direction with the axial direction being the device depth direction. As shown in Fig. 6, a recess 140a extending in the device depth direction is formed on the outer peripheral surface of the pressure roll 140. When the sheet member P passes between the pressure roll 140 and the heating roll 130, the leading end holding portion 68 that grips the leading end of the sheet member P is accommodated in this recess 140a.

[0053] As shown in FIG. 5, a pair of shaft portions 148 are formed at both ends in the device depth direction, have a smaller diameter than the pressure roll 140, and extend in the axial direction.

[0054] Furthermore, the main heating section 120 includes a support member 156 that supports the pressure roll 140, and a biasing member 158 that biases the pressure roll 140 toward the heating roll 130 via the support member 156. A pair of support members 156 are provided. The pair of support members 156 are respectively disposed so as to rotatably support the pair of shaft portions 148 of the pressure roll 140 from below.

[0055] In this configuration, the pair of biasing members 158 bias the pressure roll 140 toward the heating roll 130, causing the pressure roll 140 to press the sheet member P toward the heating roll 130. Furthermore, a rotational force is transmitted to the pressure roll 140 from a driving member (not shown), causing it to rotate. The heating roll 130 then rotates in response to the rotating pressure roll 140. Furthermore, the heating roll 130 and the pressure roll 140 sandwich and transport the sheet member P to which the toner image has been transferred, causing the toner image to be heated and fixed to the sheet member P.

[0056] (Function of Image Forming Apparatus) In the image forming apparatus 10 shown in Fig. 1, a toner image is formed on the sheet member P as follows. First, the charger 22 for each color shown in Fig. 2 uniformly negatively charges the surface of the image carrier 21 for each color at a predetermined potential. Next, based on image data input from the outside, the exposure device 23 irradiates the charged surface of the image carrier 21 for each color with exposure light to form an electrostatic latent image.

[0057] As a result, electrostatic latent images corresponding to the image data are formed on the surfaces of the image carriers 21. The developing devices 24 for each color develop the electrostatic latent images and visualize them as toner images. The primary transfer rolls 33 of the transfer device 30 shown in FIG. 1 sequentially transfer the toner images formed on the surfaces of the image carriers 21 for each color to the transfer belt 31 at the primary transfer position T.

[0058] Thus, the sheet material P sent from the storage section 50 to the supply path 40 by the delivery roll 58 is handed over to a tip holding section 68 (see FIG. 3) of the chain gripper 66 and transported. The sheet material P transported by the chain gripper 66 is sent out toward the secondary transfer position NT. At the secondary transfer position NT, the sheet material P is sandwiched between the transfer belt 31 and the transfer cylinder 36 and transported, so that the toner image on the surface of the transfer belt 31 is transferred to the surface of the sheet material P.

[0059] Furthermore, the fixing device 100 fixes the toner image transferred onto the surface of the sheet material P onto the sheet material P, and the sheet material P transported by the chain gripper 66 is sent out to the discharge path 42. The sheet material P sent out to the discharge path 42 is discharged to the outside of the apparatus main body 10a.

[0060] (Main part configuration) Next, a description will be given of the transfer device 30. The transfer device 30 is an example of a transfer system. 1, the transfer device 30 includes a transfer belt 31, a plurality of rolls 32, a primary transfer roll 33, a transfer cylinder 36, a scraping member 38, and a control unit 90 (see FIG. 8). The transfer device 30 is an example of a transfer system.

[0061] [Roll 32] 7, roll 32c, which is disposed upstream of roll 32a in the rotation direction of transfer belt 31, presses transfer belt 31 from the rear surface thereof and functions as a tension applying roll that applies tension to transfer belt 31. Roll 32b also functions as a drive roll that is rotationally driven by a driving force applied from drive source 34. Furthermore, a detection unit 54 (see FIG. 8(A)) is provided that detects torque generated in roll 32b based on the power applied to drive source 34.

[0062] Roll 32d is disposed between rolls 32a and 32d in the rotation direction of transfer belt 31, and presses transfer belt 31 from the back surface of transfer belt 31 so as to make transfer belt 31 jut outward, and rotates following the rotation of transfer belt 31. An applying unit 52, which is a powder brake that applies a braking force (braking force) to roll 32d, is provided on the shaft of roll 32d, and roll 32d functions as a braking roll. Roll 32a is an example of a winding roll, roll 32b is an example of a driving roll, and roll 32d is an example of a braking roll.

[0063] The applying unit 52 and the roll 32d constitute the braking unit 60. Here, in this embodiment, the braking unit 60 is a member whose main purpose is to apply a braking force to the transfer belt 31 by contacting the rear surface of the transfer belt 31, and does not include the scraping member 38 described later.

[0064] Further, a nipping roll 48 is provided on the opposite side of the roll 32d across the transfer belt 31, nipping the transfer belt 31 between the roll 32d and the nipping roll 48. The nipping roll 48 is an example of a nipping roll.

[0065] [Transfer cylinder 36] As shown in FIG. 7, the transfer cylinder 36 is disposed on the opposite side of the roll 32a across the transfer belt 31, and is rotated by the driving force of a driving source 56 being transmitted thereto.

[0066] [Scraping member 38] As shown in FIG. 7, the scraping member 38 is disposed between the rolls 32a and 32d in the rotational direction of the transfer belt 31, and has the function of scraping off any deposits adhering to the surface of the transfer belt 31 from the transfer belt 31.

[0067] [Control unit 90] -Hardware configuration of the control unit 90- 8A, the control unit 90 has a CPU (Central Processing Unit) 91, a ROM (Read Only Memory) 92, a RAM (Random Access Memory) 93, a storage 94, and a communication interface (I / F) 95. Each component is connected to each other so as to be able to communicate with each other via a bus 99. The CPU 91 is an example of a processor.

[0068] The CPU 91 is a central processing unit that executes various programs and controls each part. That is, the CPU 91 reads a program from the ROM 92 or the storage 94, and executes the program using the RAM 93 as a working area. The CPU 91 controls each component and performs various calculation processes according to the program stored in the ROM 92 or the storage 94.

[0069] In this embodiment, for example, the ROM 92 or the storage 94 stores a braking program for controlling the application unit 52 based on the torque information detected by the detection unit 54 to vary the braking force of the roll 32d.

[0070] The RAM 93 temporarily stores programs or data as a working area. The storage 94 is configured with a hard disk drive (HDD) or a solid state drive (SSD), and stores various programs including an operating system, and various data.

[0071] The communication interface 95 is an interface for communicating with the detection unit 54 and the like, and uses standards such as Ethernet (registered trademark), FDDI, and Wi-Fi (registered trademark), for example.

[0072] When executing the braking program, the control unit 90 uses the hardware resources described above to realize various functions. Next, a functional configuration of the control unit 90 that realizes the various functions will be described.

[0073] -Functional configuration of the control unit 90- 8(B), the control unit 90 has a receiving unit 96, a derivation unit 97, and an operating unit 98. Each functional configuration is realized by the CPU 91 reading and executing a driving program stored in the ROM 92 or the storage 94. The control unit 90 will be described in detail together with the operation described later.

[0074] (Function of main components) The operation of the main components will be described below. Specifically, the process of controlling the rotation speed of the transfer belt 31 when the toner image formed in the toner image forming unit 20 is transferred onto the transfer belt 31 and the toner image transferred onto the transfer belt 31 is transferred onto the sheet material P will be described with reference to the flow chart shown in FIG.

[0075] When the receiving unit 96 of the control unit 90 receives an instruction to start the transfer operation, the operating unit 98 operates the drive source 34 to rotate the roll 32b, thereby rotating the transfer belt 31. Furthermore, the operating unit 98 operates the drive source 56 to rotate the transfer cylinder 36 and rotate the chain 72. Then, in step S100, the receiving unit 96 of the control unit 90 detects the torque generated in the roll 32b from the detection unit 54.

[0076] Furthermore, in step S200, the derivation unit 97 derives a braking force to be applied to the roll 32d. Specifically, the derivation unit 97 derives a braking force to be applied to the roll 32d so that the torque generated in the roll 32b fluctuates and the fluctuating torque falls within a threshold. In other words, the derivation unit 97 derives a braking force to be applied to the roll 32d so that the tension of the transfer belt 31 in the portion between the rolls 32d and 32b fluctuates and the fluctuating tension falls within a threshold.

[0077] Then, in step S300, the operating unit 98 controls the applying unit 52 to apply a braking force to the roll 32d.

[0078] Furthermore, in step S400, the receiving unit 96 receives the print information, and when the print job is completed, the series of operations ends. On the other hand, if the print job is to be continued, the process returns to the above-mentioned step S100 and the series of operations is executed again.

[0079] As described above, a braking force is applied to the roll 32d so that the torque of the roll 32b falls within the threshold value. In other words, a braking force is applied to the roll 32d so that the tension of the transfer belt 31 in the portion between the rolls 32d and 32b falls within the threshold value.

[0080] Here, an example of the reason why the torque generated in the roll 32b varies and the reason why the torque generated in the roll 32b is within the threshold value will be described while comparing with the transfer device 230 according to a comparative embodiment. First, the configuration of the transfer device 230 according to the comparative embodiment will be described, focusing mainly on the parts that differ from the transfer device 30 of this embodiment. As shown in FIG. 11, the transfer device 230 is not provided with the roll 32d.

[0081] As an example of the reason why the torque generated in the roll 32b varies, the degree of adhesion on the surface of the transfer belt 31 may vary partially in the circumferential direction of the transfer belt 31. In this case, the frictional force generated between the transfer cylinder 36, which is driven to rotate, and the transfer belt 31 varies.

[0082] In the transfer device 230 according to the comparative embodiment shown in FIG. 11, the tension of the transfer belt 31 in the rotation direction of the transfer belt 31 varies in a portion between the rolls 32a and 32b (portion d5 shown in FIG. 11) due to the variation in frictional force. The torque generated in the roll 32b also varies due to this variation. If the roll 32b is driven to rotate in a state in which the tension of the transfer belt 31 in the portion between the rolls 32a and 32b varies, the rotation speed (conveyance amount) of the transfer belt 31 in the portion to which the toner image is transferred from the image carrier 21 varies. If the rotation speed of the transfer belt 31 varies, the images transferred from the image carriers 21 of each color to the transfer belt 31 are shifted. This is called image shifting.

[0083] On the other hand, in the transfer device 30 of the present embodiment shown in Fig. 7, the torque generated in the roll 32b is set within a threshold value in order to cause a fluctuation in tension only in the portion of the transfer belt 31 between the rolls 32a and 32d (portion d1 in Fig. 7). In this way, the fluctuation in tension is suppressed in the portion of the transfer belt 31 downstream of the roll 32d, and therefore the fluctuation in the rotational speed (conveyance amount) of the transfer belt 31 in the portion where the toner image is transferred from the image carrier 21 is also suppressed. When the fluctuation in the rotational speed of the transfer belt 31 is suppressed, image misalignment occurring in the images transferred from the image carriers 21 of each color to the transfer belt 31 is suppressed.

[0084] 10A and 10B, the frictional force between the rotating transfer cylinder 36 and the transfer belt 31 varies depending on whether or not the sheet member P is sandwiched between the transfer cylinder 36 and the transfer belt 31. Furthermore, the frictional force may vary depending on the density of the toner image formed on the sheet member P.

[0085] (summary) As described above, in the transfer device 30, the roll 32d provided downstream of the roll 32a and upstream of the roll 32b in the rotation direction of the transfer belt 31 applies a braking force to the rotating transfer belt 31. This suppresses image misalignment that occurs in the images transferred from the toner image forming units 20 of each color to the transfer belt 31, compared to when the back surface of the transfer belt 31 downstream of the roll 32a and upstream of the roll 32b in the rotation direction of the transfer belt 31 is free.

[0086] Moreover, the transfer device 30 is configured to apply a braking force to the roll 32d that rotates following the rotation of the transfer belt 31. Therefore, wear of the transfer belt is suppressed compared to the case where a non-rotatable braking unit is used.

[0087] In the transfer device 30, a nipping roll 48 is disposed on the opposite side of the roll 32d across the transfer belt 31, nipping the transfer belt 31 with the roll 32d. Therefore, the braking force of the roll 32d is transmitted to the transfer belt 31 more effectively than in the case where the transfer belt floats relative to the braking roll.

[0088] In the transfer device 30, a clamping roll 48 is disposed on the opposite side of the roll 32d across the transfer belt 31, clamping the transfer belt 31 with the roll 32d. This reduces wear on the transfer belt 31 compared to when a non-rotatable clamping member is used.

[0089] In the transfer device 30, the control unit 90 controls the application unit 52 so that the torque generated in the roll 32d falls within a threshold value based on the torque detected by the detection unit 54. Therefore, the application unit 52 is controlled with a simpler configuration than when the tension generated in the transfer belt is detected to control the braking unit.

[0090] In the transfer device 30, the control unit 90 controls the application unit 52 based on the torque detected by the detection unit 54 so that the torque generated in the roll 32d falls within the threshold value. This makes it easier to bring the torque generated in the roll 32d within the threshold value compared to the case where a non-rotatable braking member is used.

[0091] In the transfer device 30, a scraping member 38 for scraping off deposits from the transfer belt 31 is provided downstream of the roll 32a and upstream of the roll 32d in the rotation direction of the transfer belt 31. This suppresses image misalignment in the images transferred from the toner image forming units 20 of each color to the transfer belt 31, compared to a case in which the fluctuation in tension of the transfer belt caused by the frictional force between the scraping member and the transfer belt is directly transmitted to the transfer belt at the portion where the image is transferred, causing the rotation speed of the transfer belt to fluctuate.

[0092] Furthermore, since the image forming apparatus 10 includes the transfer device 30, degradation in the quality of the output image is suppressed compared to when the image forming apparatus 10 includes the transfer device 230 according to the comparative embodiment.

[0093] Although the present disclosure has been described in detail with respect to a specific embodiment, it is clear to those skilled in the art that the present disclosure is not limited to the embodiment, and various other embodiments are possible within the scope of the present disclosure. For example, in the above embodiment, the rotating roll 32d is used to apply a braking force to the transfer belt 31, but a non-rotatable braking member may be used to apply a braking force to the transfer belt 31. In this case, the effect achieved by using the roll 32d is not achieved.

[0094] In the above embodiment, the transfer belt 31 is sandwiched between the sandwich roll 48 and the roll 32d by using the sandwich roll 48, but the sandwich roll 48 may not be used. In this case, the effect achieved by using the sandwich roll 48 is not achieved.

[0095] In the above embodiment, the control unit 90 controls the application unit 52 based on the torque detected by the detection unit 54 so that the torque generated in the roll 32b falls within the threshold value, but the braking unit may be controlled based on pre-stored braking conditions. In this case, however, the effect of controlling the application unit 52 based on the torque detected by the detection unit 54 is not achieved.

[0096] (((1))) a transfer belt that is endless and onto which images held by a plurality of image holders are sequentially transferred; a winding roll around which the transfer belt is wound and which rotates in accordance with the rotation of the transfer belt; a drive roll around which the transfer belt is wound, the drive roll being disposed downstream of the winding roll in the rotation direction of the transfer belt and upstream of a portion where an image is transferred to the transfer belt, the drive roll applying a drive force to the transfer belt to rotate the transfer belt; a transfer cylinder disposed on the opposite side of the winding roll with the transfer belt interposed therebetween, the transfer cylinder rotating to transfer an image on the transfer belt to a recording medium being conveyed; a braking unit that is disposed downstream of the winding roll and upstream of the drive roll in a rotation direction of the transfer belt, and that applies a braking force to the transfer belt by contacting a rear surface of the rotating transfer belt; A transcription system comprising:

[0097] (((2))) The braking unit includes a braking roll around which the transfer belt is wound and which rotates in response to the rotation of the transfer belt, and an applying unit that applies a braking force to the braking roll. The transcription system described in (((1))).

[0098] (((3))) a pinching member disposed on the opposite side of the brake roll with the transfer belt sandwiched therebetween; The transcription system described in (((1))).

[0099] (((4))) The pinching member is a pinching roll that rotates in accordance with the transfer belt. The transcription system according to (((3))).

[0100] (((5))) A detection unit that detects a torque generated in the driving roll; at least one processor; The processor controls the braking unit based on a detection result of the detection unit so that a torque generated in the driving roll falls within a threshold value. A transfer system according to any one of (((1))) to (((4))).

[0101] (((6))) the braking unit includes a braking roll wrapped around the transfer belt and an applying unit that applies a braking force to the braking roll, The processor controls the application unit. The transcription system according to (((4))).

[0102] (((7))) a scraping member for scraping off deposits from the transfer belt is disposed downstream of the winding roll and upstream of the braking unit in the rotation direction of the transfer belt; A transfer system according to any one of (((1))) to (((6))).

[0103] (((8))) A transcription system according to any one of (((1))) to (((7))), a fixing device that fixes the image transferred onto the recording medium onto the recording medium; An image forming system comprising:

[0104] According to the transfer system of (((1))), the transfer belt rotates by the driving force of the drive roll, and the transfer cylinder that transfers the image on the transfer belt to a recording medium is driven to rotate, and image misalignment that occurs in images transferred from multiple image carriers to the transfer belt can be suppressed compared to a case in which the back surface of the transfer belt downstream of the winding roll and upstream of the drive roll in the rotation direction of the transfer belt is free.

[0105] According to the transfer system of (((2))), wear on the transfer belt can be suppressed compared to a case in which a non-rotatable braking unit is used.

[0106] According to the transfer system of (((3))), the braking force of the brake roll can be transmitted to the transfer belt more effectively than in a case where the transfer belt floats relative to the brake roll.

[0107] According to the transfer system of (((4))), wear on the transfer belt can be suppressed compared to a case in which a non-rotatable pinching member is used.

[0108] According to the transfer system of (((5))), the braking unit can be controlled with a simpler configuration than when the braking unit is controlled by detecting the tension generated in the transfer belt.

[0109] According to the transfer system of (((6))), the torque generated in the drive roll can be easily controlled within the threshold value, compared to the case where a non-rotatable braking portion is used.

[0110] According to the transfer system of (((7))), image misalignment occurring in images transferred from multiple image carriers to the transfer belt can be suppressed, compared to a case in which fluctuations in the tension of the transfer belt caused by friction between the scraping member and the transfer belt are directly transmitted to the transfer belt in the portion where the image is transferred, causing fluctuations in the rotational speed of the transfer belt.

[0111] According to the image forming system of (((8))), deterioration in the quality of the output image can be suppressed compared to a case in which a transfer system is provided in which fluctuations in tension on the transfer belt are directly transmitted to the part of the transfer belt where the image is transferred, causing fluctuations in the rotational speed of the transfer belt. [Explanation of symbols]

[0112] 10 Image forming device (an example of an image forming system) 21 Image holder 30 Transcription device (an example of a transcription system) 31 Transfer belt 32a Roll (an example of a wrapping roll) 32b Roll (an example of a driving roll) 32d roll (an example of a braking roll) 36 Transfer cylinder 38 Scraping member 48 Clamping roll (an example of a clamping roll) 52 Granting Department 54 Detection section 60 Braking part 90 Control section 91 CPU (an example of a processor) 100 Fixing device

Claims

1. a transfer belt that is endless and onto which images held by a plurality of image holders are sequentially transferred; a winding roll around which the transfer belt is wound and which rotates in accordance with the rotation of the transfer belt; a drive roll around which the transfer belt is wound, the drive roll being disposed downstream of the winding roll in the rotation direction of the transfer belt and upstream of a portion where an image is transferred to the transfer belt, the drive roll applying a drive force to the transfer belt to rotate the transfer belt; a transfer cylinder disposed on the opposite side of the winding roll with the transfer belt interposed therebetween, the transfer cylinder rotating to transfer an image on the transfer belt to a recording medium being conveyed; a braking unit that is disposed downstream of the winding roll and upstream of the drive roll in a rotation direction of the transfer belt, and that applies a braking force to the transfer belt by contacting a rear surface of the rotating transfer belt; A transcription system comprising:

2. The braking unit includes a braking roll around which the transfer belt is wound and which rotates in response to the rotation of the transfer belt, and an applying unit that applies a braking force to the braking roll. The transfer system of claim 1 .

3. a pinching member disposed on the opposite side of the brake roll with the transfer belt sandwiched therebetween; The transfer system of claim 2 .

4. The pinching member is a pinching roll that rotates in accordance with the transfer belt. The transfer system of claim 3 .

5. A detection unit that detects a torque generated in the driving roll; at least one processor; The processor controls the braking unit based on a detection result of the detection unit so that a torque generated in the driving roll falls within a threshold value. The transfer system of claim 1 .

6. the braking unit includes a braking roll wrapped around the transfer belt and an applying unit that applies a braking force to the braking roll, The processor controls the application unit. The transfer system of claim 5 .

7. a scraping member for scraping off deposits from the transfer belt is disposed downstream of the winding roll and upstream of the braking unit in the rotation direction of the transfer belt; The transfer system of claim 1 .

8. A transfer system according to any one of claims 1 to 7, a fixing device that fixes the image transferred onto the recording medium onto the recording medium; An image forming system comprising:

Images