JP2012181352A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress variation of a moving speed generated at a second transfer position from transmitting to a first transfer position in a transfer body.SOLUTION: An image forming device comprises: an image forming part in which an image is formed; an annular transfer body for transferring the image, which is formed in the image forming part, transferred at a first transfer position and circularly moved, to a second transfer position; a transfer member for transferring the image, which is transferred to the second transfer position by the transfer body, to a recording medium at the second transfer position; a first winding roll around which the transfer body is wound and that is disposed upstream of the transfer body in the moving direction relative to the first transfer position and downstream of the transfer body in the moving direction relative to the second transfer position; a second winding roll around which the transfer body is wound and that is disposed upstream of the transfer body in the moving direction relative to the first transfer position and downstream of the transfer body in the moving direction relative to the second transfer position; a first inertia body disposed on the first winding roll; and a second inertia body disposed on the second winding roll.

Description

  The present invention relates to an image forming apparatus.

  In Patent Document 1, when an image is not formed on an image carrier, at least one of the image carrier and the pressure roll is moved by a driving force from a driving unit that rotationally drives the image carrier to The contact portion is moved by using the urging force of the urging means that presses the image carrier and the pressure roll in synchronization with the timing when the transfer medium enters between the pressure contact portion of the image carrier and the pressure roll. An image recording apparatus configured to release the separation is disclosed.

  In Patent Document 2, a flywheel 25 for increasing the moment of inertia used to stabilize the rotational speed of the photosensitive drum 1 is provided on the photosensitive drum rotating shaft 20 separately from the photosensitive drum 1, and In addition, a configuration is disclosed in which the flywheel 25 is provided at a position inside the bearings 21 and 22 that support the photosensitive drum rotating shaft 20 instead of outside.

  In Patent Document 3, in an image forming apparatus having a rotating body 21 and flywheels 23 and 24 attached to a shaft 22 of the rotating body, the shaft 22 of the rotating body 21 has a detent 22a at one end. The flywheel includes a first type flywheel 23 having a hole fitted in the center of the rotation preventing portion of the shaft and a second type flywheel 24 fixed to the end portion of the shaft. In addition, one or more first type flywheels 23 are fitted to the rotation preventing portion of the shaft, the second type flywheel 24 is fixed to the shaft 22, and the second type flywheel and the first A configuration in which a flywheel of a type is integrally coupled is disclosed.

JP-A-6-274051 JP-A-7-281555 JP 2004-29375 A

  It is an object of the present invention to suppress the movement of the moving speed generated at the second transfer position in the transfer body from being transmitted to the first transfer position.

  According to the first aspect of the present invention, there is provided an image forming portion on which an image is formed, and an annular shape in which an image formed by the image forming portion is transferred at a first transfer position and is circulated and conveyed to the second transfer position. A transfer member for transferring the image conveyed by the transfer member to the second transfer position onto a recording medium at the second transfer position, and the transfer member is wound around the transfer member to the first transfer position. A first winding roll provided on the upstream side in the movement direction and on the downstream side in the movement direction of the transfer body with respect to the second transfer position, and the transfer body is wound around and the transfer with respect to the first transfer position is performed. A second winding roll provided on the downstream side in the movement direction of the body and on the upstream side in the movement direction of the transfer body with respect to the second transfer position; and a first inertia body provided on the first winding roll. And a second inertia provided on the second winding roll. And body, an image forming apparatus comprising a.

  According to a second aspect of the present invention, a plurality of the first winding rolls are provided, and the first inertial body has a maximum angle around which the transfer body is wound among the plurality of first winding rolls. The image forming apparatus according to claim 1, wherein the image forming apparatus is provided in the apparatus.

  According to a third aspect of the present invention, a plurality of the first winding rolls are provided, and the first inertial body is provided on the one having the smallest diameter among the plurality of first winding rolls. An image forming apparatus according to claim 1.

  According to a fourth aspect of the present invention, a plurality of the second winding rolls are provided, and the second inertial body has a maximum angle around which the transfer body is wound among the plurality of second winding rolls. The image forming apparatus according to claim 1, wherein the image forming apparatus is provided in the apparatus.

  According to a fifth aspect of the present invention, a plurality of the second winding rolls are provided, and the second inertial body is provided on the plurality of second winding rolls having the smallest diameter. 5. The image forming apparatus according to any one of 1 to 4.

  According to the configuration of the first aspect of the present invention, the movement speed fluctuation generated at the second transfer position in the transfer body is transmitted to the first transfer position as compared with the configuration without the first inertia body and the second inertia body. Can be suppressed.

  According to the configuration of the second aspect of the present invention, compared to the configuration in which the first inertia body is provided in the plurality of first winding rolls in which the angle around which the transfer body is wound is not the maximum, the second in the transfer body. The effect of suppressing the fluctuation of the moving speed generated at the transfer position from being transmitted to the first transfer position is high.

  According to the configuration of the third aspect of the present invention, the moving speed generated at the second transfer position in the transfer body as compared with the configuration in which the first inertia body is provided in the plurality of first winding rolls whose diameter is not minimum. Is highly effective in suppressing the fluctuation of the signal from being transmitted to the first transfer position.

  According to the configuration of the fourth aspect of the present invention, in the transfer body, the second inertial body is provided in the second winding roll as compared with the configuration in which the second inertial body is provided on the one where the angle around which the transfer body is wound is not maximum. The effect of suppressing the fluctuation of the moving speed generated at the transfer position from being transmitted to the first transfer position is high.

  According to the structure of Claim 5 of this invention, compared with the structure which provides a 2nd inertia body in the thing with a diameter which is not the minimum among several 2nd winding rolls, the moving speed generate | occur | produced in the 2nd transfer position in the transfer body. Is highly effective in suppressing the fluctuation of the signal from being transmitted to the first transfer position.

1 is a schematic diagram illustrating a configuration of an image forming apparatus according to an exemplary embodiment. FIG. 2 is a schematic diagram illustrating a configuration of an image forming unit according to the present embodiment. It is the schematic which shows the structure of the transfer part which concerns on this embodiment. 6 is a graph showing a speed fluctuation rate of a speed fluctuation of the intermediate transfer belt generated at the first transfer position when the thick paper enters the second transfer position. (A) Configuration without a flywheel (B) Configuration with a flywheel only on a tension applying roll (C) Configuration of this embodiment It is the schematic which shows the modification which changed the winding roll which provides a flywheel. FIG. 10 is a schematic diagram illustrating a modification in which a flywheel is applied to a winding roll wound around the outer peripheral side of an intermediate transfer belt.

Below, an example of an embodiment concerning the present invention is described based on a drawing.
(Configuration of image forming apparatus according to the present embodiment)
First, the configuration of the image forming apparatus according to the present embodiment will be described. FIG. 1 is a schematic diagram illustrating a configuration of an image forming apparatus according to the present embodiment.

  The image forming apparatus 10 according to the present embodiment is an apparatus that forms a color image or a black and white image. As shown in FIG. 1, the image forming apparatus 10 includes a first casing 10A that constitutes a horizontal side portion (left side in FIG. 1). And a second housing 10B that is detachably connected to the first housing 10A and forms the other side in the horizontal direction (the right side in FIG. 1).

  An image signal processing unit 13 that performs image processing on image data sent from an external device such as a computer is provided on the second housing 10B.

  On the other hand, the first special color (V), second special color (W), yellow (Y), magenta (M), cyan (C), and black (K) toners are provided on the upper portion of the first housing 10A. Toner cartridges 14V, 14W, 14Y, 14M, 14C, and 14K are provided so as to be replaceable along the horizontal direction.

  The first special color and the second special color are appropriately selected from colors other than yellow, magenta, cyan, and black (including transparency). In the following description, the first special color (V), the second special color (W), yellow (Y), magenta (M), cyan (C), and black (K) are distinguished for each component. Is described by adding any one of V, W, Y, M, C, and K after the reference numeral, and the first special color (V), the second special color (W), yellow (Y), and magenta (M ), Cyan (C), and black (K) are not distinguished, V, W, Y, M, C, and K are omitted.

  A plurality of image forming units 16 as an example of an image forming unit for forming an image are provided below the toner cartridge 14 along the horizontal direction so as to correspond to the toner cartridges 14. In the present embodiment, the plurality of image forming units 16 is composed of six corresponding to the toners of the respective colors. An exposure unit 40 is provided for each image forming unit 16 between each toner cartridge 14 and the image forming unit 16.

  The exposure unit 40 receives the image data subjected to the image processing by the image signal processing unit 13 from the image signal processing unit 13, and the exposure light L (see FIG. 2) modulated according to the image data is described later. It is comprised so that the body 18 (refer FIG. 2) may be irradiated.

  As shown in FIG. 2, each image forming unit 16 includes a photoreceptor 18 that is rotationally driven in one direction (clockwise direction in FIG. 2). By exposing the exposure light L from each exposure unit 40 to each photoconductor 18, an electrostatic latent image is formed on each photoconductor 18.

  Around each photoconductor 18, a corona discharge (non-contact charging) scorotron charger 20 as an example of a charging device for charging the photoconductor 18 and an electrostatic unit formed on the photoconductor 18 by an exposure unit 40. A developing device 22 that develops the latent image with a developer, a blade 24 as an example of a removing member that removes the developer remaining on the photoconductor 18 after the transfer, and the charge removal by irradiating the photoconductor 18 after the transfer with light. A static elimination device 26 is provided for performing the above.

  The scorotron charger 20, the developing device 22, the blade 24, and the charge removal device 26 are arranged in this order from the upstream side to the downstream side in the rotation direction of the photoconductor 18 so as to face the surface of the photoconductor 18.

  The developing device 22 includes a developer accommodating member 22A that accommodates a developer G containing toner, and a developing roll 22B that supplies the developer G accommodated in the developer accommodating member 22A to the photoconductor 18. Yes. The developer accommodating member 22A is connected to the toner cartridge 14 (see FIG. 1) through a toner supply path (not shown), and the toner is supplied from the toner cartridge 14.

  As shown in FIG. 1, below the image forming unit 16, a transfer unit 32 that transfers the toner image formed by each image forming unit 16 to the recording medium P is provided. The transfer unit 32 is a first transfer member that transfers the toner image formed by the intermediate transfer belt 34 as an example of an annular transfer member and the photoreceptor 18 of each image forming unit 16 to the intermediate transfer belt 34. A transfer roll 36 and a second transfer roll 62 as an example of a transfer member that transfers the toner image on the intermediate transfer belt 34 to the recording medium P are provided.

  The first transfer roll 36 is provided at a position facing the photoconductor 18 of each image forming unit 16 with the intermediate transfer belt 34 interposed therebetween. The first transfer roll 36 is applied with a transfer bias voltage having a polarity opposite to the toner polarity by a power supply unit (not shown). With this configuration, the toner image formed on the photoconductor 18 is transferred to the intermediate transfer belt 34 at a predetermined first transfer position T1. Specifically, the first transfer position T1 is a contact position where the intermediate transfer belt 34 and the photoconductor 18 are in contact with each other.

  The intermediate transfer belt 34 circulates and conveys the toner image transferred at the first transfer position T1 to a predetermined second transfer position T2.

  The second transfer roll 62 is applied with a transfer bias voltage having a polarity opposite to the toner polarity by a power feeding unit (not shown). By applying the transfer bias voltage, the second transfer roller 62 is configured to transfer the toner image conveyed by the intermediate transfer belt 34 to the second transfer position T2 to the recording medium P at the second transfer position T2. A more specific configuration of the transfer unit 32 will be described later.

  Below the transfer unit 32, two recording medium storage units 48 for storing recording media such as paper are provided along the horizontal direction.

  Each recording medium accommodating portion 48 can be pulled out from the first housing 10A. Above one end side (the right side in FIG. 1) of each recording medium container 48, a delivery roll 52 that sends the recording medium P from each recording medium container 48 to the transport path 60 is provided.

  In each recording medium accommodating portion 48, a bottom plate 50 on which the recording medium P is placed is provided. The bottom plate 50 is lowered by an instruction of a control unit (not shown) when the recording medium accommodating portion 48 is pulled out from the first housing 10A. When the bottom plate 50 is lowered, a space in which the user replenishes the recording medium P is formed in the recording medium accommodating portion 48.

  When the recording medium accommodating portion 48 pulled out from the first housing 10A is attached to the first housing 10A, the bottom plate 50 is raised by an instruction from the control means. As the bottom plate 50 moves up, the uppermost recording medium P placed on the bottom plate 50 and the delivery roll 52 come into contact with each other.

  On the downstream side in the recording medium conveyance direction of the sending roll 52 (hereinafter sometimes simply referred to as “downstream side”), a separation roll 56 that separates the recording media P sent from the recording medium accommodating portion 48 one by one. Is provided. A plurality of transport rolls 54 that transport the recording medium P downstream in the transport direction are provided on the downstream side of the separation roll 56.

  The conveyance path 60 provided between the recording medium storage unit 48 and the transfer unit 32 is configured to fold the recording medium P sent out from the recording medium storage unit 48 to the left side in FIG. The folding portion 60B extends to the second transfer position T2 between the second transfer roll 62 and the opposing roll 45 so as to be folded to the right side in FIG. On the upstream side of the second transfer position T2 in the conveyance direction, a conveyance roll (registration roll) 64 for adjusting the movement timing of the toner image on the intermediate transfer belt 34 and the conveyance timing of the recording medium P is provided.

  A preliminary path 66 extending from the side surface of the first housing 10 </ b> A is provided so as to join the second folding portion 60 </ b> B of the transport path 60. A recording medium P sent out from a recording medium accommodation unit (not shown) arranged adjacent to the first housing 10 </ b> A enters the conveyance path 60 through the spare path 66.

  On the downstream side of the second transfer position T2, a plurality of conveying belts 70 that convey the recording medium P on which the toner image has been transferred toward the second casing 10B are provided in the first casing 10A. A transport belt 80 that transports the transported recording medium P to the downstream side is provided in the second casing 10B.

  Each of the plurality of conveyance belts 70 and the conveyance belt 80 is formed in an annular shape and is wound around a pair of winding rolls 72. The pair of winding rolls 72 are respectively arranged on the upstream side and the downstream side in the conveyance direction of the recording medium P, and when one of them is driven to rotate, the conveyance belt 70 (conveyance belt 80) moves in one direction (in FIG. 1). Cycle in the clockwise direction.

  A fixing device 82 that heats and fixes the toner image transferred to the recording medium P to the recording medium P is provided on the downstream side of the conveyance belt 80.

  The fixing device 82 includes a fixing belt 84 and a pressure roll 88 disposed so as to come into contact with the fixing belt 84 from below. A fixing unit is formed between the fixing belt 84 and the pressure roll 88 to fix the toner image by pressurizing and heating the recording medium P.

  The fixing belt 84 is formed in an annular shape and is wound around the drive roll 89 and the driven roll 90. The drive roll 89 faces the pressure roll 88 from above, and the driven roll 90 is disposed above the drive roll 89.

  Each of the driving roll 89 and the driven roll 90 includes a heating unit such as a halogen heater. As a result, the fixing belt 84 is heated.

  As shown in FIG. 1, a conveyance belt 98 that conveys the recording medium P sent from the fixing device 82 to the downstream side is provided on the downstream side of the fixing device 82. The conveyor belt 98 is formed in the same manner as the conveyor belt 70.

  As an example of a conveying device that conveys the recording medium P, a cooling device 100 that conveys the recording medium P heated by the fixing device 82 and cools the recording medium P is provided on the downstream side of the conveying belt 98. .

  On the downstream side of the cooling device 100, there is provided a correction device 170 that conveys the recording medium P and corrects the curl of the recording medium P.

  A detection device 180 that detects a toner density defect, an image defect, an image position defect, and the like of the toner image fixed on the recording medium P is provided on the downstream side of the correction device 170.

  The detection device 180 detects the reflected light emitted from the light source to the recording medium P and reflected upward by the recording medium P by a detection element such as a CCD (Charge Coupled Device) image sensor, thereby causing a toner density defect and an image defect. Image position defects and the like are detected.

  On the downstream side of the detection device 180, a discharge roll 198 that discharges the recording medium P on which an image is formed on one side to a discharge unit 196 attached to the side surface of the second housing 10B is provided.

  On the other hand, when images are formed on both sides, the recording medium P sent from the detection device 180 is conveyed to the reversing path 202 provided on the downstream side of the detection device 180.

  The reversing path 202 includes a branch path 202A that branches from the transport path 60, a paper transport path 202B that transports the recording medium P transported along the branch path 202A toward the first housing 10A, and a paper transport path. A reversing path 202C is provided in which the recording medium P transported along 202B is folded back in the reverse direction and transported in a switchback manner so that the front and back surfaces are reversed.

  With this configuration, the recording medium P that is switched back and conveyed by the reverse path 202C is conveyed toward the first housing 10A, and further enters the conveyance path 60 provided above the recording medium accommodating portion 48, so that the second It is sent again to the transfer position T2.

  Next, an image forming process of the image forming apparatus 10 will be described.

  The image data that has been subjected to image processing by the image signal processing unit 13 is sent to each exposure unit 40. In each exposure unit 40, each exposure light L is emitted according to the image data and exposed to each photoconductor 18 charged by the scorotron charger 20, and an electrostatic latent image is formed.

  As shown in FIG. 2, the electrostatic latent image formed on the photoconductor 18 is developed by the developing device 22, and the first special color (V), the second special color (W), yellow (Y), magenta ( M), cyan (C), and black (K) toner images are formed.

  As shown in FIG. 1, each color toner image formed on the photoreceptor 28 of each of the image forming units 16V, 16W, 16Y, 16M, 16C, and 16K is composed of six first transfer rolls 36V, 36W, 36Y, 36M, Multiple transfer is sequentially performed on the intermediate transfer belt 34 by 36C and 36K.

  The toner images of the respective colors that have been multiplex-transferred onto the intermediate transfer belt 34 are secondarily transferred by the second transfer roll 62 onto the recording medium P that has been transported from the recording medium container 48. The recording medium P onto which the toner image has been transferred is conveyed toward the fixing device 82 provided inside the second housing 10B by the conveyance belt 70.

  The toner images of the respective colors on the recording medium P are fixed on the recording medium P by being heated and pressurized by the fixing device 82. Further, the recording medium P on which the toner image is fixed is cooled by passing through the cooling device 100 and then sent to the correction device 170 to correct the curvature generated in the recording medium P.

  The recording medium P whose curvature is corrected is discharged to the discharge unit 196 by the discharge roll 198 after an image defect or the like is detected by the detection device 180.

  On the other hand, when an image is formed on a non-image surface where no image is formed (in the case of double-sided printing), after passing through the detection device 180, the recording medium P is reversed by the reversing path 202 and above the recording medium container 48. And a toner image is formed on the back surface according to the above-described procedure.

(Specific configuration of the transfer unit 32 according to the present embodiment)
Next, a specific configuration of the transfer unit 32 according to the present embodiment will be described. FIG. 3 is a schematic diagram illustrating a configuration of the transfer unit 32 according to the present embodiment.

  As shown in FIG. 3, as described above, the transfer unit 32 transfers six toner images formed on the intermediate transfer belt 34 and the photoreceptor 18 of each image forming unit 16 to the intermediate transfer belt 34. A roll 36 and a second transfer roll 62 that transfers the toner image on the intermediate transfer belt 34 to the recording medium P are provided.

  On the upstream side in the movement direction of the intermediate transfer belt 34 with respect to the first transfer position T1 and on the downstream side in the movement direction of the intermediate transfer belt 34 with respect to the second transfer position T2, a plurality of first windings around which the intermediate transfer belt 34 is wound are provided. A one-roll roll 41 is provided. Specifically, the plurality of first winding rolls 41 are upstream in the moving direction of the intermediate transfer belt 34 with respect to the first transfer position T1 in the image forming unit 16V and on the inner peripheral side of the intermediate transfer belt 34. Is provided.

  In the state where the intermediate transfer belt 34 is wound in the present embodiment, the intermediate transfer belt 34 is curved in an arc shape along the peripheral surface of the winding roll to be wound and comes into contact with the winding roll. This includes not only the state but also the state in which the intermediate transfer belt 34 is in contact with the winding roll in a straight line.

  The plurality of first winding rolls 41 include driven rolls 41 </ b> A, 41 </ b> B, and 41 </ b> D that are driven to rotate with respect to the intermediate transfer belt 34, and drive rolls 41 </ b> C that are driven by a motor 43. The driven rolls 41A, 41B, 41D and the driving roll 41C are arranged in the order of the driven roll 41A, the driven roll 41B, the driving roll 41C, and the driven roll 41D from the upstream side in the moving direction of the intermediate transfer belt 34.

  In the transfer section 32, the drive roll 41C is rotationally driven by the motor 43, so that the intermediate transfer belt 34 is driven to circulate in one direction (counterclockwise direction in FIG. 1). Further, a removal member 46A such as a blade is brought into contact with the intermediate transfer belt 34 at a position facing the drive roll 41C with the intermediate transfer belt 34 interposed therebetween, and residual toner, paper dust, and the like on the intermediate transfer belt 34 are removed. A removal device 46 is provided.

  The driven rolls 41A, 41B and 41D and the driving roll 41C have the angles around which the intermediate transfer belt 34 is wound increased in the order of the driven roll 41B, the driven roll 41A, the driven roll 41D, and the driving roll 41C. Accordingly, the drive roll 41C is a roll having a maximum angle around which the intermediate transfer belt 34 is wound among the plurality of first winding rolls 41. That is, the drive roll 41 </ b> C has a larger contact area with the intermediate transfer belt 34 than the other first winding rolls 41, and is less likely to slip between the intermediate transfer belt 34.

  The driven rolls 41B and 41D have a diameter of 18 mm, for example, and are smaller in diameter than the driven roll 41A and the driving roll 41C having a diameter of 33 mm, for example. That is, the driven rolls 41 </ b> B and 41 </ b> D are the rolls having the smallest diameter among the plurality of first winding rolls 41.

  On the downstream side in the movement direction of the intermediate transfer belt 34 with respect to the first transfer position T1 and on the upstream side in the movement direction of the intermediate transfer belt 34 with respect to the second transfer position T2, a plurality of second belts wound with the intermediate transfer belt 34 are wound. Two winding rolls 42 are provided. Specifically, the plurality of second winding rolls 42 are downstream in the moving direction of the intermediate transfer belt 34 with respect to the first transfer position T1 in the image forming unit 16K and on the inner peripheral side of the intermediate transfer belt 34. Is provided.

  Accordingly, on the moving path of the intermediate transfer belt 34, the plurality of first transfer positions T1 are sandwiched between the plurality of first winding rolls 41 and the plurality of second winding rolls 42 so as to be sandwiched between them. Two winding rolls 42 are arranged.

  The plurality of second winding rolls 42 are driven rolls 42A, 42C, and 42D that are driven to rotate with respect to the intermediate transfer belt 34, and tensions that are driven to rotate with respect to the intermediate transfer belt 34 and that apply tension to the intermediate transfer belt 34. And an application roll 42B. The driven rolls 42A, 42C, 42D and the tension applying roll 42B are arranged in the order of the driven roll 42A, the tension applying roll 42B, the driven roll 42C, and the driven roll 42D from the upstream side in the moving direction of the intermediate transfer belt 34.

  The tension applying roll 42B is provided with a pressing spring (elastic member) 47 as an example of an urging member that urges the tension applying roll 42B to the intermediate transfer belt 34. The tension applying roll 42 </ b> B is configured to apply tension to the intermediate transfer belt 34 by pressing the tension applying roll 42 </ b> B against the intermediate transfer belt 34 by the pressing spring 47.

  In the driven rolls 42A, 42C, 42D and the tension applying roll 42B, the angles around which the intermediate transfer belt 34 is wound are increased in the order of the driven roll 42D, the driven roll 42C, the driven roll 42A, and the tension applying roll 42B. Therefore, the tension applying roll 42B is the roll having the maximum angle around which the intermediate transfer belt 34 is wound, among the plurality of second winding rolls 42. That is, the tension applying roll 42 </ b> B has a larger contact area with the intermediate transfer belt 34 than the other second winding rolls 42, and is less likely to slip between the intermediate transfer belt 34.

  The driven roll 42A has a diameter of 18 mm, for example, and is smaller in diameter than the tension applying roll 42B and the driven rolls 42C and 42D having a diameter of 33 mm, for example. That is, the driven roll 42 </ b> A is the roll having the smallest diameter among the plurality of second winding rolls 42.

  On the inner peripheral side of the intermediate transfer belt 34, a counter roll 45 that faces the second transfer roll 62 at the second transfer position T2 is wound around the intermediate transfer belt 34.

  Here, in the present embodiment, the first flywheel 91 as an example of the first inertial body is provided on the rotation shaft of the drive roll 41C. That is, the first flywheel 91 is provided coaxially with the drive roll 41C and is configured to rotate integrally with the drive roll 41C.

  The first flywheel 91 is made of a metal plate formed in a disk shape, and increases the moment of inertia in the drive roll 41C. The diameter of the first flywheel 91 is at least larger than the diameter of the drive roll 41C, for example, a diameter of 120 mm.

  The first flywheel 91 may be provided integrally with the roll body of the drive roll 41C and rotate integrally with the drive roll 41C. Further, the first flywheel 91 may be provided on a rotating shaft that rotates with the rotation of the drive roll 41 </ b> C by a transmission member such as a gear / belt, for example. That is, the first flywheel 91 may be provided on a different axis with respect to the drive roll 41C.

  Moreover, the 2nd flywheel 92 as an example of a 2nd inertia body is provided in the rotating shaft of the tension | tensile_strength provision roll 42B. That is, the second flywheel 92 is provided on the same axis as the tension applying roll 42B and is configured to rotate integrally with the tension applying roll 42B.

  The second flywheel 92 is made of a metal plate formed in a disk shape, and increases the moment of inertia in the tension applying roll 42B. The diameter of the second flywheel 92 is at least larger than the diameter of the tension applying roll 42B, and is, for example, 80 mm in diameter.

  The second flywheel 92 may be provided integrally with the roll body of the tension applying roll 42B and may rotate integrally with the tension applying roll 42B. Further, the second flywheel 92 may be provided on a rotating shaft that rotates with the rotation of the tension applying roll 42B by a transmission member such as a gear / belt. In other words, the second flywheel 92 may be provided on a different axis with respect to the tension applying roll 42B.

(Operation according to this embodiment)
Next, the operation according to this embodiment will be described.

  According to the configuration according to the present embodiment, when the recording medium P (particularly, thick paper) conveyed by the conveyance roll 64 enters the second transfer position T2 between the second transfer roll 62 and the opposing roll 45, Variations and vibrations in the moving speed due to the impact of the rush are generated in the intermediate transfer belt 34.

  The speed fluctuation and vibration generated at the second transfer position T2 in the intermediate transfer belt 34 are transmitted to the downstream side in the moving direction and the upstream side in the moving direction of the intermediate transfer belt 34. The speed fluctuation and vibration transmitted from the second transfer position T2 to the downstream side in the movement direction on the intermediate transfer belt 34 are blocked or alleviated by absorbing the energy by the drive roll 41C provided with the first flywheel 91. The The drive roll 41C provided with the first flywheel 91 has the largest angle around which the intermediate transfer belt 34 is wound among the plurality of first winding rolls 41. In comparison, slippage between the intermediate transfer belt 34 and the energy of the speed fluctuation is efficiently transmitted as the rotational energy of the first flywheel 91, and the effect of absorbing the speed fluctuation and vibration is high.

  On the other hand, the speed fluctuation and vibration transmitted from the second transfer position T2 to the upstream side in the movement direction on the intermediate transfer belt 34 are blocked by the energy absorbed by the tension applying roll 42B provided with the second flywheel 92. Or relaxed. The tension applying roll 42 </ b> B provided with the second flywheel 92 has the maximum angle around which the intermediate transfer belt 34 is wound among the plurality of second winding rolls 42. In comparison with the intermediate transfer belt 34, the slip is less likely to occur, and the energy of the speed fluctuation is efficiently transmitted as the rotational energy of the second flywheel 92, and the effect of absorbing the speed fluctuation and vibration is high.

  Thereby, speed fluctuation and vibration of the intermediate transfer belt 34 at the first transfer position T1 are prevented or suppressed. Thereby, image disturbance of the toner image transferred from the photosensitive member 18 to the intermediate transfer belt 34 at the first transfer position T1 is suppressed. In addition, fluctuations in the exposure position caused by the vibration of the intermediate transfer belt 34 being transmitted to the exposure unit 40 via the photosensitive member 18 are suppressed.

  4A is a configuration in which neither the first flywheel 91 nor the second flywheel 92 is provided in the configuration of the present embodiment, and FIG. 4B is a configuration in which the first flywheel 91 is not provided in the configuration of the present embodiment. In the configuration in which only the second flywheel 92 is provided, (C) the configuration of the present embodiment, when a thick paper (for example, thickness 0.4 mm) enters the second transfer position T2, it occurs at the first transfer position T1. Further, the speed fluctuation rate of the photosensitive member 18 due to the speed fluctuation of the intermediate transfer belt 34 is shown. In FIG. 4, the part surrounded by the solid line indicates the timing when the thick paper enters the second transfer position T2. According to FIG. 4, it can be seen that the speed fluctuation is reduced in (C) compared to (A) and (B).

  In the present embodiment, the first flywheel 91 is provided on the drive roll 41C. However, for example, as shown in FIG. 5, the first flywheel 91 may be provided on the driven roll 41D. What is necessary is just to provide the 1st flywheel 91 in either of the 1 winding rolls 41. FIG.

  Since the driven roll 41D has the smallest diameter among the plurality of first winding rolls 41, the driven roll 41D is driven as compared with the case where the first flywheel 91 is provided on the first winding roll 41 having a larger diameter than the driven roll 41D. When the first flywheel 91 is provided on the roll 41D, the arm of the moment is smaller, so the energy required for the rotation of the first flywheel 91 increases, and the effect of absorbing speed fluctuations and vibrations is high. Further, in the configuration in which the first flywheel 91 is provided on the driven roll 41D, the winding angle of the intermediate transfer belt 34 with respect to the driven roll 41D may be maximized. That is, among the plurality of first winding rolls 41, the first flywheel 91 may be provided on the roll having the maximum angle and the minimum diameter around which the intermediate transfer belt 34 is wound. . This configuration can also be realized by minimizing the diameter of the drive roll 41C provided with the first flywheel 91.

  In the present embodiment, the second flywheel 92 is provided on the tension applying roll 42B. However, for example, as shown in FIG. 5, the second flywheel 92 may be provided on the driven roll 42D. The second flywheel 92 may be provided on any one of the second winding rolls 42.

  Since the driven roll 42D has the smallest diameter among the plurality of second winding rolls 42, the driven roll 42D is driven as compared with the case where the second flywheel 92 is provided on the second winding roll 42 having a larger diameter than the driven roll 42D. When the second flywheel 92 is provided on the roll 42D, the moment arm is smaller, so that the energy required for the rotation of the second flywheel 92 becomes larger, and the effect of absorbing speed fluctuations and vibrations is higher. Further, in the configuration in which the second flywheel 92 is provided on the driven roll 42D, the winding angle of the intermediate transfer belt 34 with respect to the driven roll 42D may be maximized. That is, among the plurality of second winding rolls 42, the second flywheel 92 may be provided on the roll having the maximum angle and the minimum diameter around which the intermediate transfer belt 34 is wound. . This configuration can also be realized by minimizing the diameter of the tension applying roll 42B provided with the second flywheel 92.

  Moreover, in this embodiment, although the 1st flywheel 91 was provided in one of the some 1st winding rolls 41, in any some or all of the some 1st winding rolls 41, The structure in which the 1st flywheel 91 is provided may be sufficient. Moreover, in this embodiment, although the 2nd flywheel 92 was provided in one of the some 2nd winding rolls 42, in any some or all of the some 2nd winding rolls 42, it is. The structure provided with the 2nd flywheel 92 may be sufficient.

  Moreover, in this embodiment, although the 1st winding roll 41 and the 2nd winding roll 42 were each comprised by multiple, at least one of the 1st winding roll 41 and the 2nd winding roll 42 is, You may be comprised by one.

  Further, in the present embodiment, there are a plurality of first transfer positions T1, and the plurality of first transfer positions T1 are applied with tension on the driving roll 41C (first winding roll 41) on the moving path of the intermediate transfer belt 34. The arrangement is such that the roll 42B (second winding roll 42) is sandwiched between the rolls 42B. However, there is one first transfer position T1, and the first transfer position T1 is used as an intermediate transfer. The configuration may be such that the drive roll 41C (first winding roll 41) and the tension applying roll 42B (second winding roll 42) are sandwiched on the moving path of the belt 34.

  In the present embodiment, the plurality of first winding rolls 41 and the plurality of second winding rolls 42 are wound around the intermediate transfer belt 34 on the inner peripheral side of the intermediate transfer belt 34. At least a part of the first winding roll 41 and the plurality of second winding rolls 42 may be wound around the intermediate transfer belt 34 on the outer peripheral side of the intermediate transfer belt 34.

  As the first winding roll 41 wound around the intermediate transfer belt 34 on the outer peripheral side of the intermediate transfer belt 34, for example, as shown in FIG. A tension applying roll 141 that applies tension to the transfer belt 34 is used. The tension applying roll 141 is provided with a pressing spring (elastic member) 151 as an example of an urging member that urges the tension applying roll 141 to the intermediate transfer belt 34. The tension applying roll 141 is configured to apply tension to the intermediate transfer belt 34 by the pressing spring 151 pressing the tension applying roll 141 to the intermediate transfer belt 34.

  As the second winding roll 42 wound around the intermediate transfer belt 34 on the outer peripheral side of the intermediate transfer belt 34, for example, as shown in FIG. A tension applying roll 142 that applies tension to the transfer belt 34 is used. The tension applying roll 142 is provided with a pressing spring (elastic member) 152 as an example of an urging member that urges the tension applying roll 142 to the intermediate transfer belt 34. The tension applying roll 142 is configured to apply tension to the intermediate transfer belt 34 by pressing the tension applying roll 142 against the intermediate transfer belt 34 by the pressing spring 152. The tension applying roll 142 comes into contact with the toner image transferred to the intermediate transfer belt 34. However, the tension applying roll 142 has a surface treatment for suppressing the adhesion of toner to the outer peripheral surface of the tension applying roll 142, and the tension applying roll 142. The toner image is maintained on the intermediate transfer belt 34 by applying a bias voltage having the same polarity as the toner polarity. In FIG. 6, both the tension applying roll 141 and the tension applying roll 142 are illustrated, but only one of the configurations may be used.

  In the present embodiment, the counter roll 45 is not provided with a flywheel as an inertial body, but the flywheel similar to the first flywheel 91 or the second flywheel 92 is provided for the counter roll 45. The structure which provides may be sufficient.

  The present invention is not limited to the above-described embodiment, and various modifications, changes, and improvements can be made. For example, the modification examples described above may be appropriately combined.

16 Image forming unit (an example of an image forming unit)
34 Intermediate transfer belt (an example of a transfer member)
41 First winding roll 42 Second winding roll 91 First flywheel (an example of a first inertial body)
92 Second flywheel (an example of a second inertial body)
T1 First transfer position T2 Second transfer position

Claims (5)

An image forming unit on which an image is formed;
An image formed by the image forming unit is transferred at the first transfer position, and is circularly moved to convey the image to the second transfer position;
A transfer member for transferring an image conveyed by the transfer body to a second transfer position to a recording medium at the second transfer position;
A first winding roll wound around the transfer body and provided upstream in the movement direction of the transfer body with respect to the first transfer position and downstream in the movement direction of the transfer body with respect to the second transfer position. When,
A second winding roll wound around the transfer body and provided on the downstream side in the movement direction of the transfer body with respect to the first transfer position and on the upstream side in the movement direction of the transfer body with respect to the second transfer position. When,
A first inertial body provided on the first winding roll;
A second inertial body provided on the second winding roll;
An image forming apparatus comprising: A plurality of the first winding rolls are provided,
2. The image forming apparatus according to claim 1, wherein the first inertia member is provided on the one of the plurality of first winding rolls having the maximum angle around which the transfer member is wound. A plurality of the first winding rolls are provided,
3. The image forming apparatus according to claim 1, wherein the first inertia body is provided on one of the plurality of first winding rolls having the smallest diameter. A plurality of the second winding rolls are provided,
The said 2nd inertia body is provided in what has the largest angle by which the said transfer body was wound among these several 2nd winding rolls. Image forming apparatus. A plurality of the second winding rolls are provided,
5. The image forming apparatus according to claim 1, wherein the second inertia body is provided on the plurality of second winding rolls having the smallest diameter. 6.

Images