JP2010169920A - Belt carrying device and image forming apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a belt carrying device and an image forming apparatus using the same, improving separating performance of a record medium from a belt without deteriorating the quality of an image. <P>SOLUTION: The belt carrying device includes: the belt carrying the record medium; and a record medium separating roller abutting on the inside of the belt and provided with a spiral projection formed on the surface thereof. The spiral projection abuts on the belt to deform the belt and generate a wavy swell on the belt surface, whereby a gap is formed between the record medium and the belt to improve the separating performance of the record medium from the belt. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a belt conveying apparatus and an image forming apparatus for conveying a recording medium such as paper provided in an image forming apparatus such as a copying machine, a facsimile machine, and a printer, and more particularly to a recording medium on a belt surface without degrading image quality. The present invention relates to a belt conveyance device and an image forming apparatus that are separated from each other to prevent a paper jam.

  In an electrophotographic image forming apparatus, image information is written on a uniformly charged image carrier to form an electrostatic latent image, and the electrostatic latent image is developed by a developing device to form a visible image. The visible image is transferred directly to a recording medium or transferred to a recording medium via a transfer belt, and the recording medium onto which the visible image has been transferred is fixed by a fixing device to form an image.

  In such an image forming apparatus, it has been proposed to arrange a separation device for separating the recording medium on the belt in order to prevent paper jamming due to the winding of the recording medium around the belt.

  Japanese Patent Laid-Open No. 7-92820 discloses an image forming apparatus in which a recording medium is separated and conveyed by a transfer belt to form an image, and a backup roller having a large diameter in the axial direction is provided on a backup roller of a recording medium separating portion of the transfer belt. Separation member having a claw portion that is arranged with a separation roller having a small-diameter concave portion and that protrudes closer to the axis than the outer diameter of the convex portion at a position corresponding to the concave portion of the separation roller, in contact with the transfer belt surface. A belt conveying device in which is arranged is disclosed.

  Japanese Patent Application Laid-Open No. 11-334924 discloses an image forming apparatus that drives a belt stretched by a plurality of stretching rollers including a driving roller and conveys a recording medium held by the belt. When the recording medium is separated from the driving roller unit, the driving unit rotates together with the driven unit driven by the shaft, and the driven unit has a convex portion having a larger diameter than the driving unit and a concave portion having a smaller diameter than the driving unit. In addition, there is disclosed a belt conveying device in which the recording medium is corrugated in the axial direction of the driving roller, and a force for separating the recording medium from the belt is applied to improve the separation performance of the recording medium from the belt.

In JP-A-7-92820, Japanese Patent Laid-Open No. 11-334924

  However, the belt conveying device disclosed in Japanese Patent Application Laid-Open No. 7-92820 requires precise adjustment of the position of the claw portion in order to install the claw portion in a non-contact manner with the belt. It is a factor of up. In addition, the recording medium is separated from the portion having the nail portion, and the separation of the recording medium is delayed in the portion without the nail portion, so that image unevenness due to the separation discharge occurs in the portion without the nail portion and the nail portion. Furthermore, when separating the recording medium, the image portion on the recording medium may be disturbed by rubbing the nail portion, and the separation of the recording medium from the belt and obtaining a high-quality image are obtained. There is a problem that it is difficult to achieve both.

  Further, in the belt conveying device disclosed in Japanese Patent Application Laid-Open No. 11-334924, the driving roller is clearly separated in the axial direction by the driving portion and the driven portion having the concavo-convex portion, and from the driven portion having the concavo-convex portion. Since the recording medium is separated and the separation of the recording medium from the driving unit is delayed, image unevenness due to separation discharge occurs in the driven unit and the driving unit having uneven portions. Further, since the convex portion of the driven portion is always in contact with the belt, the surface of the belt is damaged and the image quality is deteriorated.

  The present invention solves the above-mentioned problems of the prior art, and provides a belt conveyance device that improves the separation of the recording medium from the belt without degrading the image quality, and an image forming apparatus using the same. With the goal.

  In order to solve the above problems, a belt conveying device of the present invention includes a belt that conveys a recording medium, and a recording medium separating roller that abuts on the inner side of the belt and forms a spiral protrusion on the surface. It is characterized by. When the spiral protrusion contacts the belt, the belt is deformed, a wave-like undulation is generated on the belt surface, a gap is formed between the recording medium and the belt, and the separation of the recording medium from the belt is improved. can do.

  The belt conveying device of the present invention is characterized in that the spiral direction of the spiral protrusion is formed so as to be different on one side and the other side in the axial direction of the recording medium separating roller. By forming the spiral projections in different directions, a complicated undulation that the recording medium cannot follow on the belt surface is generated, and a gap is formed between the recording medium and the belt, so that the recording medium is separated from the belt. Can be improved.

  Further, the belt conveying device of the present invention is characterized in that the spiral protrusion is formed so that a contact point locus position is a non-integer multiple in one round of the belt. Generation of moire fringes (interference fringes) can be prevented.

  The belt conveying apparatus of the present invention is characterized in that the recording medium separating roller is rotatable about an axis and is driven by the belt. The belt can run smoothly.

  In the belt conveying apparatus of the present invention, the recording medium separating roller is integrated with a shaft and is driven by a driving unit. The separation property of the recording medium from the belt can be improved, and the belt meandering can be prevented by controlling the rotational speed of the recording medium separation roller with respect to the peripheral speed of the belt.

  In the belt conveying device of the present invention, the recording medium separating roller is a tension roller that is positioned at an end portion in the conveying direction of the recording medium and winds the belt. Since the recording medium separation roller can also be used as a belt stretching roller, the arrangement of the rollers can be reduced.

  In the belt conveying apparatus of the present invention, the recording medium separating roller is located at an end in the conveying direction of the recording medium, and is arranged on the upstream side in the recording medium conveying direction from a position of a stretching roller around which the belt is wound. It is characterized by that. Separation of the recording medium from the belt can be performed near the position where the recording medium is conveyed to the next step.

  The image forming apparatus of the present invention includes a latent image carrier on which an electrostatic latent image is formed, a developing device that develops the electrostatic latent image with toner and develops the toner image on the latent image carrier, A transfer belt to which the toner image of the latent image carrier is transferred, a transfer device for transferring the toner image on the transfer belt to a recording medium, and a fixing device for fixing the toner image on the recording medium, Any one of the belt conveyance devices described above is used as a recording medium conveyance unit of the transfer device. It is possible to prevent the recording medium from being jammed at the transfer portion.

  The image forming apparatus of the present invention includes a latent image carrier on which an electrostatic latent image is formed, a developing device that develops the electrostatic latent image with toner and develops the toner image on the latent image carrier, A transfer belt to which the toner image of the latent image carrier is transferred, a transfer device for transferring the toner image on the transfer belt to a recording medium, and a fixing device for fixing the toner image on the recording medium, The fixing device includes a heating roller and a pressure belt, and the belt conveying device described in any one of the above is used as a recording medium conveying unit of the fixing device. It is possible to prevent the recording medium from being jammed in the fixing unit.

1 is a diagram illustrating an entire embodiment of an image forming apparatus of the present invention. It is a figure which shows embodiment which applied this invention to the secondary transfer part. It is a figure which shows embodiment which applied this invention to the secondary transfer part. FIG. 3 is a diagram illustrating an embodiment in which the present invention is applied to a fixing unit. It is a figure which shows one Embodiment of a recording-medium separation roller. It is a figure which shows the deformation | transformation state of the belt by contact | abutting to the belt of a spiral protrusion. It is a figure which shows one Embodiment of a recording-medium separation roller. It is a figure which shows one Embodiment of a recording-medium separation roller. (A) (b) It is a figure which shows the case where the rotational speed of a recording-medium separation roller and the circumferential speed of a belt are the same. (A) (b) It is a figure which shows the case where the rotational speed of a recording-medium separation roller is faster than the circumferential speed of a belt. (A) (b) It is a figure which shows the case where the rotational speed of a recording-medium separation roller is slower than the circumferential speed of a belt. It is a figure which shows the arrangement | positioning state of a position sensor.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an example of an embodiment of an image forming apparatus according to the present invention.

  As shown in FIG. 1, the image forming apparatus 10 includes four image forming stations 15 (Y, M, C, K), an intermediate transfer belt 70, and a secondary transfer unit 80, and further includes a fixing unit 90, a user. And a display unit (not shown) formed of a liquid crystal panel, and a control unit (not shown) that controls these units and operates as an image forming apparatus.

  The image forming station 15 (Y, M, C, K) has a function of forming an image with toners of yellow (Y), magenta (M), cyan (C), and black (K), respectively. Since the configuration of the image forming station 15 (Y, M, C, K) is the same, the image forming station 15Y will be described below.

  As shown in FIG. 1, the image forming station 15Y includes a charging unit 30Y, an exposure unit 40Y, a developing unit 50Y, and a primary transfer unit along the rotation direction of a photoconductor 20Y as an example of an image carrier. .

  The photoreceptor 20Y has a cylindrical base material and a photosensitive layer formed on the outer peripheral surface thereof, and can rotate around a central axis. In the present embodiment, the photoreceptor 20Y rotates clockwise as indicated by an arrow. To do.

  The charging unit 30Y is a device for charging the photoconductor 20Y. From the exposure unit 40Y, a latent image is formed on the charged photoreceptor 20Y by irradiating a laser.

  The exposure unit 40Y includes a semiconductor laser, a polygon mirror, an F-θ lens, and the like, and is charged with a modulated laser based on an image signal input from a host computer (not shown) such as a personal computer or a word processor. Irradiate onto the photoconductor 20Y.

  The development unit 50Y is a device for developing the latent image formed on the photoreceptor 20Y using yellow (Y) toner. In the developing unit 50Y, a developing roller 51Y and a supply roller 52Y are disposed in a developing chamber to which toner is supplied from a replaceable toner cartridge. A regulating blade 53Y contacts the developing roller 51Y to thin the toner on the developing roller 51Y. Stratify.

  In the primary transfer unit, a primary transfer bias is applied by the primary transfer roller 65Y in the primary transfer portion B1, and the yellow toner image formed on the photoreceptor 20Y is transferred to the intermediate transfer belt 70. When the four color toners are sequentially transferred in the primary transfer portions B 1, B 2, B 3 and B 4, a full color toner image is formed on the intermediate transfer belt 70.

  The intermediate transfer belt 70 is an endless belt stretched around a belt driving roller 71a and driven rollers 71b, 71d, 71e, and 71f, and is rotationally driven while being in contact with the photoreceptor 20 (Y, M, C, K). The

  The secondary transfer unit 80 is a device for transferring a single color toner image or a full color toner image formed on the intermediate transfer belt 70 to a recording medium such as paper, film, or cloth.

  The fixing unit 90 is configured by a heating roller 90a and a pressure belt 90b, and is a device for fusing a single color toner image or a full color toner image transferred onto a recording medium to the recording medium to obtain a permanent image.

  Next, the operation of the image forming apparatus 10 configured as described above will be described. First, when an image signal and a control signal from a host computer (not shown) are input to the main controller of the image forming apparatus via an interface, the photoconductor 20Y and the developing unit are controlled by a unit controller based on a command from the main controller. The developing roller 51Y provided in 50Y, the intermediate transfer belt 70, and the like rotate. The photoconductor 20Y is sequentially charged by the charging unit 30Y at the charging position while rotating.

  The charged area of the photoconductor 20Y reaches the exposure position as the photoconductor 20Y rotates, and a latent image corresponding to yellow Y image information is formed in the area by the exposure unit 40Y.

  The latent image formed on the photoreceptor 20Y reaches the development position as the photoreceptor 20Y rotates, and is developed by the development unit 50Y. Thereby, a toner image is formed on the photoreceptor 20Y.

  The toner image formed on the photoconductor 20Y reaches the position of the primary transfer portion B1 as the photoconductor 20Y rotates, and is transferred to the intermediate transfer belt 70 by the primary transfer unit. At this time, in the primary transfer unit, a primary transfer voltage having a polarity opposite to the charging polarity of the toner is applied from the primary transfer roller 65Y. As a result, the four color toner images formed on the respective photoreceptors 20 (Y, M, C, K) are transferred to overlap the intermediate transfer belt 70, and a full color toner image is formed on the intermediate transfer belt 70. Is done.

  The intermediate transfer belt 70 is driven by transmitting a driving force from a belt driving means such as a motor via a belt driving roller 71a.

  The full color toner image formed on the intermediate transfer belt 70 is transferred to a recording medium such as paper by the secondary transfer unit 80. In the secondary transfer unit 80, a belt driving roller 71a as a backup roller and a secondary transfer roller 82 face each other with the intermediate transfer belt 70 interposed therebetween. A secondary transfer voltage having a polarity opposite to that of the toner is applied from the secondary transfer roller 82, and the toner image transferred to the intermediate transfer belt 70 is secondarily transferred to a recording medium. The recording medium is transported from the paper feed tray to the secondary transfer unit 80 via a paper feed roller, a gate roller 94, and a transport guide 94a.

  The recording medium on which the full color toner image is transferred by the secondary transfer unit 80 is conveyed to the fixing unit 90 via the conveyance guide 94b. The fixing unit 90 includes a heating element such as a halogen heater, the temperature of which is controlled to a predetermined fixing temperature, and a heating roller 90a that is rotationally driven, and a pressure belt that is stretched between two stretching rollers 90c and 90d. 90b. The toner image is fused to the recording medium by being heated and pressurized by the fixing unit 90. After passing through the fixing unit 90, the recording medium is discharged by a discharge roller 95 through a conveyance guide 95a.

  On the other hand, the photosensitive member 20 (Y, M, C, K) is neutralized by a neutralizing unit (not shown) after passing through the primary transfer portions B1, B2, B3, B4 to form the next latent image. To prepare for charging.

  An intermediate transfer belt cleaning device (not shown) is installed on the driven roller 71b side of the intermediate transfer belt 70 after the secondary transfer, and cleans the intermediate transfer belt 70 after the secondary transfer.

  FIG. 2 is a view showing an embodiment in which the recording medium separating roller 100 for improving the separation property of the recording medium from the belt according to the present invention is applied to the secondary transfer unit 80.

  In the secondary transfer unit 80, a belt driving roller 71a is positioned between stretching rollers 71d and 71f around which the intermediate transfer belt 70 is wound, and the secondary transfer roller 82 is used as a backup roller with the belt driving roller 71a as a backup roller. To form a secondary transfer portion. The recording medium is conveyed to the secondary transfer portion via the gate roller 94 and the conveyance guide 94a, and a secondary transfer voltage having a polarity opposite to that of the toner is applied from the secondary transfer roller 82, and the toner transferred to the intermediate transfer belt 70 is transferred. Secondary transfer of the image to the recording medium. The recording medium on which the toner image is transferred is discharged by the discharging device 96. The moving direction of the intermediate transfer belt 70 is changed by a stretching roller 71d. The recording medium to which the toner image has been transferred is separated from the intermediate transfer belt 70 whose movement direction is changed by the stretching roller 71d, and is conveyed to the fixing unit 90, which is the next step, via the conveyance guide 94b.

  If the recording medium is not separated from the intermediate transfer belt 70 in the conveyance of the recording medium in the secondary transfer unit 80, the recording medium is wound around the tension roller 71d and a paper jam occurs. In particular, when the recording medium is thin paper, many paper jams occur due to winding. In order to prevent this, the recording medium separating roller 100 is disposed between the secondary transfer section and the stretching roller 71d positioned at the end of the recording medium conveyance path. By disposing the recording medium separation roller 100, the recording medium after the secondary transfer is separated from the intermediate transfer belt 70 and conveyed to the fixing unit 90 via the conveyance guide 94b.

  FIG. 3 is a diagram showing another embodiment in which the recording medium separation roller 100 for improving the separation property of the recording medium from the belt of the present invention is applied to the secondary transfer unit 80. In this embodiment, the recording medium separating roller 100 that also serves as a stretching roller is disposed at the position where the stretching roller 71d is positioned at the end of the recording medium conveyance path. Since the recording medium separating roller 100 also serves as a stretching roller, the arrangement of the rollers can be reduced, and the recording medium after the secondary transfer is separated from the intermediate transfer belt 70 and conveyed to the fixing unit 90 via the conveyance guide 94b. The

  FIG. 4 is a diagram showing an embodiment in which the recording medium separating roller 100 for improving the separation property of the recording medium from the belt according to the present invention is applied to the fixing unit 90.

  The fixing unit 90 includes a heating element such as a halogen heater, the temperature of which is controlled to a predetermined fixing temperature, and a heating roller 90a that is rotationally driven, and a pressure belt that is stretched between two stretching rollers 90c and 90d. 90b. In the conveyance path between the stretching rollers 90c and 90d, the recording medium separating roller 100 is disposed on the upstream side in the conveyance direction of the recording medium near the stretching roller 90c located at the end of the conveyance path on the downstream side in the conveyance direction of the recording medium. To do. By disposing the recording medium separating roller 100, the recording medium after fixing is separated from the pressure belt 90b, conveyed to the sheet discharge roller 95 through the conveyance guide 95a, and discharged.

  FIG. 5 is a diagram showing a first embodiment of a recording medium separating roller 100 that improves the separation of the recording medium from the belt of the present invention.

  The recording medium separating roller 100 is rotatably supported by a shaft 101 and is driven by an intermediate transfer belt 70 or a pressure belt 90b.

On the surface of the recording medium separating roller 100, a spiral protrusion 102 is continuously formed.
As shown in FIG. 6, when the spiral protrusion 102 abuts against the intermediate transfer belt 70 or the pressure belt 90 b, the intermediate transfer belt 70 or pressure belt 90 b spirals along the spiral protrusion 102. Transforms into A complicated undulation that the recording medium 200 cannot follow on the surface of the intermediate transfer belt 70 or the pressure belt 90b is generated, and a gap is formed between the recording medium 200 and the intermediate transfer belt 70 or the pressure belt 90b. Separation from the intermediate transfer belt 70 or the pressure belt 90b can be improved.

  The spiral protrusion 102 of the recording medium separating roller 100 is formed such that the locus of contact point movement to the intermediate transfer belt 70 or the pressure belt 90b is a non-integer multiple of one rotation of the intermediate transfer belt 70 or the pressure belt 90b. To do. This is because if the contact point movement locus of the spiral protrusion 102 is an integral multiple of one rotation of the intermediate transfer belt 70 or the pressure belt 90b, the contact point movement locus overlaps and moire fringes (interference fringes) are generated.

  FIG. 7 is a diagram showing a second embodiment of the recording medium separating roller 100 that improves the separation of the recording medium from the belt of the present invention.

  The recording medium separating roller 100 is rotatably supported by a shaft 101 and is driven by an intermediate transfer belt 70 or a pressure belt 90b.

  On one side of the surface of the recording medium separating roller 100 in the axial direction, a spiral protrusion 102 is continuously formed. Further, on the other side in the axial direction of the surface of the recording medium separating roller 100, a spiral protrusion 102 ′ having a spiral direction opposite to the spiral protrusion 102 formed on one side is formed. . When the spiral ridges 102 and 102 ′ contact the intermediate transfer belt 70 or the pressure belt 90 b, the intermediate transfer belt 70 or pressure belt 90 b is deformed in a spiral shape along the spiral ridges 102 and 102 ′. To do. A complicated undulation that the recording medium 200 cannot follow on the surface of the intermediate transfer belt 70 or the pressure belt 90b is generated, and a gap is formed between the recording medium 200 and the intermediate transfer belt 70 or the pressure belt 90b. Separation from the intermediate transfer belt 70 or the pressure belt 90b can be improved.

  The spiral protrusions 102 and 102 'of the recording medium separating roller 100 have a contact point movement locus on the intermediate transfer belt 70 or the pressure belt 90b that is a non-integer multiple of one rotation of the intermediate transfer belt 70 or the pressure belt 90b. To form. This is because if the spiral protrusions 102 and 102 'contact point movement locus is an integral multiple of one rotation of the intermediate transfer belt 70 or the pressure belt 90b, the contact point movement locus overlaps and moire fringes (interference fringes) are generated.

  FIG. 8 is a diagram showing a third embodiment of the recording medium separating roller 100 that improves the separation of the recording medium from the belt of the present invention.

  The recording medium separating roller 100 is integrated with a shaft 101, and a rotation driving unit 103 is disposed at one end of the shaft 101 and is rotated.

On the surface of the recording medium separating roller 100, a spiral protrusion 102 is continuously formed.
When the spiral protrusion 102 abuts on the inner side of the intermediate transfer belt 70 or the pressure belt 90b, the intermediate transfer belt 70 or the pressure belt 90b is deformed in a spiral shape along the spiral protrusion 102. A complicated undulation that the recording medium 200 cannot follow on the surface of the intermediate transfer belt 70 or the pressure belt 90b is generated, and a gap is formed between the recording medium 200 and the intermediate transfer belt 70 or the pressure belt 90b. Separation from the intermediate transfer belt 70 or the pressure belt 90b can be improved.

  FIGS. 9A and 9B are diagrams illustrating a case where the rotational speed V1 of the recording medium separating roller 100 by the rotation driving unit 103 and the peripheral speed V2 of the intermediate transfer belt 70 or the pressure belt 90b are V1 = V2. .

  When V1 = V2, a force in a direction perpendicular to the belt conveyance direction is not applied to the intermediate transfer belt 70 or the pressure belt 90b.

  10A and 10B are diagrams illustrating a case where the rotational speed V1 of the recording medium separating roller 100 by the rotational driving unit 103 and the peripheral speed V2 of the intermediate transfer belt 70 or the pressure belt 90b are V1> V2. .

  When V1> V2, the speed of the recording medium separation roller 100 and the intermediate transfer belt 70 or the pressure belt 90b is applied to the intermediate transfer belt 70 or the pressure belt 90b with which the spiral protrusion 102 of the recording medium separation roller 100 abuts. As a reaction force due to the difference, a force in the anti-spiral direction opposite to the spiral direction of the spiral protrusion 102 of the recording medium separating roller 100 is applied, and in a direction orthogonal to the belt conveyance direction indicated by the arrow in FIG. The intermediate transfer belt 70 or the pressure belt 90b is moved closer.

  FIGS. 11A and 11B are diagrams illustrating a case where the rotational speed V1 of the recording medium separating roller 100 by the rotation driving unit 103 and the peripheral speed V2 of the intermediate transfer belt 70 or the pressure belt 90b are V1 <V2. .

  When V1 <V2, the speed of the recording medium separation roller 100 and the intermediate transfer belt 70 or the pressure belt 90b is applied to the intermediate transfer belt 70 or the pressure belt 90b with which the spiral protrusion 102 of the recording medium separation roller 100 abuts. As a reaction force due to the difference, a force in the spiral direction of the spiral protrusion 102 of the recording medium separating roller 100 is applied, and the intermediate transfer belt 70 or the additional force is applied in a direction perpendicular to the belt conveyance direction indicated by the arrow in FIG. Close the pressure belt 90b.

  As shown in FIG. 12, position sensors A, B, C, and D are arranged in the vicinity of the intermediate transfer belt 70 or the pressure belt 90b. The position sensor sensors A, B, C, and D detect a deviation in a direction perpendicular to the conveyance direction of the intermediate transfer belt 70 or the pressure belt 90b. By controlling the rotation driving means 103 based on the detected data, the rotation speed V1 of the recording medium separating roller 100 is adjusted with respect to the peripheral speed V2 of the intermediate transfer belt 70 or the pressure belt 90b, and intermediate transfer is performed. The deviation of the belt 70 or the pressure belt 90b is corrected.

  10: image forming apparatus, 15 (Y, M, C, K): image forming station, 20 (Y, M, C, K): photoconductor, 30 (Y, M, C, K): charging unit, 40 (Y, M, C, K): exposure unit, 50 (Y, M, C, K): development unit, 65 (Y, M, C, K): primary transfer roller, 70: intermediate transfer belt, 71a: Belt drive roller, 71b, 71d, 71e, 71f: tension roller, 80: secondary transfer unit, 82: secondary transfer roller, 90: fixing unit, 90a: heating roller, 90b: pressure belt, 90c, 90d: Stretching roller, 94: gate roller, 94a, 94b: conveyance guide, 95: discharge roller, 95a: conveyance guide, 96: static elimination device, 100: recording medium separation roller, 101: shaft, 102: spiral ridge , 103 Driving means, 200: recording medium

Claims (9)

A belt for conveying a recording medium;
A recording medium separating roller which is in contact with the inside of the belt and has a spiral protrusion formed on the surface;
A belt conveying device comprising: The belt conveying device according to claim 1, wherein the spiral direction of the spiral protrusion is formed so as to be different between one side and the other side in the axial direction of the recording medium separating roller. The belt conveying device according to claim 1, wherein the spiral protrusion is formed such that a contact point locus position is a non-integer multiple around the belt. The belt conveying apparatus according to claim 1, wherein the recording medium separating roller is rotatable with respect to an axis and is driven by the belt. The belt conveying apparatus according to claim 1, wherein the recording medium separating roller is integrated with a shaft and is driven by a driving unit. The belt conveyance device according to any one of claims 1 to 5, wherein the recording medium separation roller is a tension roller that is positioned at an end in a conveyance direction of the recording medium and winds the belt. 6. The recording medium separating roller is disposed at an upstream side in the recording medium conveyance direction from a position of a stretching roller that is positioned at an end in the conveyance direction of the recording medium and on which the belt is wound. The belt conveyance device according to any one of the above. A latent image carrier on which an electrostatic latent image is formed;
A developing device for developing the electrostatic latent image with toner and developing the toner image on the latent image carrier;
A transfer belt onto which the toner image of the latent image carrier is transferred;
A transfer device for transferring the toner image of the transfer belt to a recording medium;
A fixing device for fixing a toner image on the recording medium;
With
An image forming apparatus using the belt conveying device according to claim 1 as a recording medium conveying unit of the transfer device. A latent image carrier on which an electrostatic latent image is formed;
A developing device for developing the electrostatic latent image with toner and developing the toner image on the latent image carrier;
A transfer belt onto which the toner image of the latent image carrier is transferred;
A transfer device for transferring the toner image of the transfer belt to a recording medium;
A fixing device for fixing a toner image on the recording medium;
With
8. The image forming apparatus according to claim 1, wherein the fixing device includes a heating roller and a pressure belt, and the belt conveying device according to claim 1 is used as a recording medium conveying unit of the fixing device.

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