JP2011008023A - Band driving mechanism and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a band driving mechanism capable of prolonging service life of a band member and to provide an image forming device equipped with this band driving mechanism.SOLUTION: This band driving mechanism is constituted by applying fixing parts 26, 27 being more easily worn than umbrella-shaped members 24, 25 on conical parts 242, 252 of the umbrella-shaped members 24, 25 to prevent wear of surfaces of the conical parts 242, 252 being in contact with the fixing members 26, 27 of the umbrella-shaped members 24, 25.

Description

  The present invention relates to a band driving mechanism and an image forming apparatus.

  2. Description of the Related Art Conventionally, a belt driving mechanism is known in which a tubular and belt-like endless belt is stretched around a plurality of stretching rolls, and the endless belt is circulated between the plurality of stretching rolls. With respect to such a belt drive mechanism, proposals have been made to prevent the endless belt from being damaged. For example, Patent Document 1 discloses an endless belt that is stretched between a plurality of rolls including tension rolls having both ends tapered toward the outside, and an inner peripheral surface that is in contact with the plurality of rolls. A technique has been proposed in which a regulating member that regulates the movement of the tension roll in the axial direction is provided in a portion extending along the edge, and both ends of the tension roll are formed of a material having a small friction coefficient with respect to the regulating member. .

JP 2000-284636 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a band driving mechanism that realizes a long life of a band member and an image forming apparatus including the band driving mechanism.

The belt drive mechanism according to claim 1 comprises:
A band member wound in a tubular shape;
A plurality of tension rotating members rotating in contact with the inner peripheral surface of the band member, wherein the band members are stretched across each other and the band members circulate and move between each other;
A drive unit for driving the belt member to circulate and move between the tension rotary members;
A movable member that also serves as a part of the plurality of tension rotating members, and is movable relative to the other tension rotating members while maintaining the tension of the belt member;
Umbrella-shaped members provided at both ends of the moving member with the tip facing outward,
And a fixing member having a wear property higher than the wear property of the umbrella-shaped member, the position being fixed, which corresponds to the umbrella-shaped surface of the umbrella-shaped member.

  The band driving mechanism according to claim 2 is the band driving mechanism according to claim 1, wherein the fixing member hits the umbrella-shaped surface of the umbrella-shaped member on the surface, and the surface shape is maintained even if the contacted surface is worn. It is characterized by having a member shape.

  According to a third aspect of the present invention, in the band driving mechanism according to the first or second aspect, the drive unit also serves as at least one of the tension rotating member.

  According to a fourth aspect of the present invention, there is provided the belt drive mechanism according to any one of the first to third aspects, wherein the drive unit includes a tension rotating member other than the moving member of the tension rotating member. It is also a thing that doubles as a feature.

The image forming apparatus according to claim 5
A band member wound in a tubular shape;
A plurality of tension rotating members rotating in contact with the inner peripheral surface of the band member, wherein the band members are stretched across each other and the band members circulate and move between each other;
A drive unit for driving the belt member to circulate and move between the tension rotary members;
A movable member that also serves as a part of the plurality of tension rotating members, and is movable relative to the other tension rotating members while maintaining the tension of the belt member;
Umbrella-shaped members provided at both ends of the moving member with the tip facing outward,
And a fixing member having a wear property higher than the wear property of the umbrella-shaped member, the position being fixed, which corresponds to the umbrella-shaped surface of the umbrella-shaped member.

An image forming apparatus according to a sixth aspect is the image forming apparatus according to the fifth aspect,
An image carrier for holding an image on the surface;
An image forming unit that forms an image on the surface of the image carrier,
The belt member circulates on a circulation path that is close to or in contact with the image carrier at a predetermined position;
The image forming apparatus includes a transfer unit that transfers an image on the image holding member to the surface of the band member and / or the surface of a recording medium conveyed by the band member.

  In the band drive mechanism according to the first aspect, the life of the band member can be extended.

  In the band drive mechanism according to the second aspect, the running stability of the band member can also be extended.

  In the band drive mechanism according to the third aspect, the device can be made compact.

  In the belt drive mechanism according to the fourth aspect, the structure can be simplified.

  In the image forming apparatus according to the fifth aspect, the life of the belt member can be extended.

  In the image forming apparatus according to the sixth aspect, the life of the image transfer function can be extended.

1 is a schematic configuration diagram of a printer capable of full-color printing, which is an embodiment of an image forming apparatus of the present invention. FIG. 2 is a perspective view of a belt driving device provided in the printer shown in FIG. 1. It is a figure for demonstrating operation | movement of the belt drive device shown in FIG. It is a figure for demonstrating abrasion of the umbrella-shaped member and fixing member in the belt drive device shown in FIG. It is a figure for demonstrating operation | movement of a comparative example. It is a figure which shows the umbrella-shaped member and fixing member which were used in the Example.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a schematic configuration diagram of a printer capable of full-color printing, which is an embodiment of an image forming apparatus of the present invention.

  A printer 1 shown in FIG. 1 is a printer capable of full-color printing by a combination of Y (yellow), M (magenta), C (cyan), and K (black). The printer 1 includes Y (yellow). , M (magenta), C (cyan), and K (black), the image forming units 10Y, 10M, 10C, and 10K are provided. In each of the image forming units 10Y, 10M, 10C, and 10K, the photoreceptor rolls 11Y, 11M, 11C, and 11K, the charging devices 12Y, 12M, 12C, and 12K, the exposure devices 13Y, 13M, 13C, and 13K, and the developing device 14Y, respectively. , 14M, 14C, 14K, and primary transfer rolls 15Y, 15M, 15C, 15K. Here, the exposure devices 13Y, 13M, 13C, and 13K and the developing devices 14Y, 14M, 14C, and 14K constitute an example of an image forming unit that forms an image on the surface of the image carrier.

  The printer 1 includes a belt driving device 2 having an intermediate transfer belt 20, a driving roll 21, a steering roll 22, and an idler roll 23, which will be described in detail later. The intermediate transfer belt 20 is stretched around a drive roll 21, a steering roll 22, and an idler roll 23. Here, the drive roll 21, the steering roll 22, and the idler roll 23 correspond to an example of a plurality of stretching rolls referred to in the present invention.

  The drive roll 21 is a roll that drives the intermediate transfer belt 20 in the arrow B direction. The steering roll 22 is a roll for suppressing the movement of the intermediate transfer belt 20 in the axial direction of the steering roll 22. Further, the idle roll 23 is a roll that rotates together with the drive roll 21 and the steering roll 22. Here, the belt driving device 2 corresponds to an embodiment of the belt driving mechanism of the present invention. The intermediate transfer belt 20 corresponds to an example of a belt member according to the present invention, the drive roll 21 corresponds to an example of a drive unit according to the present invention, and the steering roll 22 corresponds to an example of a moving member according to the present invention. .

  The printer 1 further includes a secondary transfer roll 16, a fixing unit 17, and a control unit 18 that controls image formation in the printer 1.

  Here, a full color image forming operation in the printer 1 will be described.

  In this printer 1, toner image formation by the image forming unit 10Y for yellow is first started, and a constant charge is applied to the surface of the photoreceptor roll 11Y rotating in the direction of arrow A by the charging device 12Y, and then the exposure device. 13Y irradiates the surface of the photoreceptor roll 11Y with exposure light corresponding to a yellow image to form an electrostatic latent image. The electrostatic latent image is developed with yellow toner by the developing device 14Y, and a yellow toner image is formed on the surface of the photoreceptor roll 11Y. The yellow toner image formed on the surface of the photoreceptor roll 11Y is transferred by the primary transfer roll 15Y at a fixed transfer position with respect to the intermediate transfer belt 20 that has already started circulating and contacting the photoreceptor roll 11Y. Is done.

  In the magenta image forming unit 10M, the magenta toner image formed on the surface of the photoreceptor roll 11M is aligned with the timing at which the yellow toner image transferred onto the intermediate transfer belt 20 reaches the primary transfer roll 15M for magenta. A magenta toner image is formed so that the toner image reaches the primary transfer roll 15M. The magenta toner image is superimposed on the yellow toner image on the intermediate transfer belt 20 by the primary transfer roll 15M. Transcribed.

  Subsequently, the cyan and black toner images are respectively formed at the same timing as described above by the cyan and black image forming units 10C and 10K, and the formed cyan and black toner images are primary. The toner images are sequentially transferred onto the yellow and magenta toner images on the intermediate transfer belt 20 by the transfer rollers 15C and 15K. In this way, the four color toner images transferred onto the intermediate transfer belt 20 are secondarily transferred onto the paper P by the secondary transfer roll 16, transported along with the paper P in the direction of arrow C, and fixed by the fixing device 17. It is fixed on the paper P by being heated and pressed.

  Next, a detailed configuration and operation of the belt driving device 2 will be described with reference to FIGS.

  2 is a perspective view of the belt driving device provided in the printer shown in FIG. 1, and FIG. 3 is a diagram for explaining the operation of the belt driving device shown in FIG.

  The belt driving device 2 shown in FIG. 2 includes the intermediate transfer belt 2 that circulates and moves in the direction of arrow B, the driving roll 21, the steering roll 22, and the idler roll 23 as described above. On both ends of the drive roll 21 and the idler roll 23, although not shown in the figure, there are provided bearing portions into which shaft portions of the drive roll 21 and the idler roll 23 are fitted. These bearing portions are fixed to the housing.

  As shown in FIGS. 2 and 3, shaft portions 22a protrude from both ends of the steering roll 22, and umbrella-shaped members 24 and 25 are fitted into the shaft portions 22a. The umbrella-shaped member 24 includes a cylindrical portion 241 and a conical portion 242. Moreover, the umbrella-shaped member 25 is comprised from the cylindrical part 251 and the cone part 252 as shown in FIG.

  Further, the shaft portion 22a of the steering roll 22 is fitted into bearing portions (not shown), and these bearing portions are connected to a line X shown in FIG. 2 connecting the center of the bearing portion and the center of the drive roll 21. Spring members 31 and 32 are attached in a direction shifted by an angle α (an obliquely upward direction in FIG. 2), and the steering roll 22 is lifted together with the bearing portion by the spring members 31 and 32. These spring members 31, 32 apply tension to the intermediate transfer belt 20, and both ends of the steering roll 22 can freely move in the upward directions Z1, Z3 and downward directions Z2, Z4 shown in FIG. Can be done. Furthermore, since the steering roll 22 is lifted by the spring members 31 and 32, the steering roll 22 is also movable in the direction in which the shaft portion 22a extends.

  Further, as shown in FIG. 3, the belt driving device 2 is provided with fixing members 26 and 27. These fixing members 26 and 27 are fixed to a housing (not shown). For this reason, even when the belt driving device 2 is driven, the positions of the fixing members 26 and 27 do not fluctuate. The fixing members 26 and 27 are in contact with the conical portions 242 and 252 of the umbrella-shaped members 24 and 25.

  Here, when the intermediate transfer belt 20 is circulated and moved in the direction of arrow B, the intermediate transfer belt 20 being circulated is moved in the direction of movement due to the difference in the degree of balance among the drive roll 21, the steering roll 22, and the idler roll 23. A so-called belt walk that moves in the width direction orthogonal to B occurs. For example, as shown in FIG. 3A, a force indicated by an arrow Y1 is generated to move the intermediate transfer belt 20 in the axial direction of the steering roll 22, and the intermediate transfer belt 20 gradually moves in the direction of the arrow Y1. As shown in FIG. 3B, the edge of the intermediate transfer belt 20 comes into contact with the cylindrical portion 241 of the umbrella-like member 24.

  After that, the belt walk proceeds and further moves in the direction of the arrow Y1 with the edge of the intermediate transfer belt 20 in contact with the cylindrical portion 241. Here, the steering roll 22 is lifted by the spring members 31 and 32, and the conical portions 242 and 252 of the umbrella-like members 24 and 25 are in contact with the fixing members 26 and 27 whose positions are fixed. When the steering roll 22 is pushed in the right direction in the figure by the further movement of the intermediate transfer belt 20 in the arrow Y1 direction in the figure, as shown in FIG. The position of 242 that contacts the fixing member 26 moves obliquely upward, and the position of the left cone portion 252 that contacts the fixing member 27 moves obliquely downward, and the steering roll 22 tilts to the right in the figure. To go.

  Thus, when the steering roll 22 is tilted to the right in the figure, a force indicated by an arrow Y2 opposite to the force indicated by the arrow Y1 is generated on the belt walk, and the belt walk is weakened.

  As the intermediate transfer belt 20 further moves in the direction of the arrow Y1 in the figure, as shown in FIG. 3D, the positions where the conical portions 242 and 252 and the fixing members 26 and 27 abut further move. The steering roll 22 is further tilted to the right in the figure. As a result, a force indicated by an arrow Y2 opposite to the force indicated by the arrow Y1 is further applied to the belt walk, and the belt walk is stopped.

  In this way, the force indicated by the arrow Y1 that attempts to move the intermediate transfer belt 20 in the width direction is canceled out by the movement and inclination of the steering roll 22, and the traveling position of the intermediate transfer belt 20 is finally stabilized. Note that FIG. 3 illustrates an example in which a belt walk in the right direction in the drawing is first generated, but conversely, when the first belt walk is in the left direction in the drawing, the intermediate transfer belt 20 is also moved. With the movement to the left side, the steering roll 22 tilts to the left in the figure, so that the running position of the intermediate transfer belt 20 is stabilized.

  In the printer 1 shown in FIG. 1, when the running of the intermediate transfer belt 20 is stabilized, the above-described toner image superimposition is accurately performed when transferring the toner images formed by the image forming units 10Y, 10M, 10C, and 10K. As a result, a good image with little color shift can be obtained.

  By the way, in the belt drive device 2 shown in FIG. 3, since the belt walk is performed while the fixing members 26 and 27 are hitting the umbrella-like members 24 and 25, the umbrella-like members 24 and 25 and the fixing members 26 and 27 are worn. . Hereinafter, the wear of the umbrella-shaped members 24 and 25 and the fixing members 26 and 27 will be described with reference to FIG.

  FIG. 4 is a view for explaining the wear of the umbrella-like member and the fixing member in the belt driving device shown in FIG.

  The fixing members 26 and 27 shown in FIG. 4 have higher wear characteristics than the umbrella members 24 and 25. For this reason, even if the umbrella-like members 24 and 25 rub against the fixing members 26 and 27, wear is suppressed. Specifically, the wear of the surfaces of the conical portions 242 and 252 that are in contact with the fixing members 26 and 27 of the umbrella-shaped members 24 and 25 is suppressed. That is, the conical portions 242 and 252 are less likely to have a groove due to wear. For this reason, even after a long period of belt running, the change in the contact position between the conical portions 242 and 252 and the fixing members 26 and 27 as described with reference to FIG. 3 is smoothly realized. Therefore, the load on the intermediate transfer belt 20 is small over a long period of time, and the life of the intermediate transfer belt 20 is long.

  Further, as shown in FIG. 4, the conical portions 242 and 252 have a tapered shape that is inclined at a certain angle with the front facing outward with respect to a center line extending in the direction of the shaft portion 22 a of the steering roll 22. Corresponding to the above, the contact surfaces of the fixing members 26 and 27 that are in contact with the surfaces of the conical portions 242 and 252 have a shape matching the tapered shape of the conical portions 242 and 252. Further, the portions of the fixing members 26 and 27 other than the contact surfaces are columnar with a uniform thickness. For this reason, even if the contact surfaces of the fixing members 26 and 27 are worn by rubbing against the surfaces of the conical portions 242 and 252, the surface shape after the wear is the same as the surface shape before the wear. As a result, the rotational resistance caused by the frictional force generated between the umbrella-shaped members 24, 25 and the fixing members 26, 27 is constant over a long period. The rotation of the steering roll 22 is stable over a long period of time, and the running stability is maintained even if the intermediate transfer belt 20 runs for a long period of time.

  In the printer 1 shown in FIG. 1, the intermediate transfer belt 20 has a long life and the running stability is prolonged, so that stable toner image transfer is also prolonged.

  Next, a description will be given of a comparative example provided with fixing portions 201 and 202 described below in place of the fixing portions 26 and 27 having wearability higher than that of the umbrella-shaped members 24 and 25.

  FIG. 5 is a diagram for explaining the operation of the comparative example.

  The belt driving device 200 of the comparative example shown in FIG. 5 includes fixing members 201 and 202 having wear characteristics lower than the wear characteristics of the umbrella-shaped members 24 and 25. Here, as shown in FIG. 5, when the surfaces of the cone portions 242 and 252 continue to rotate while hitting the surfaces of the fixing members 201 and 202, the cone portions 242 and 252 wear and become concave. Then, since the surfaces of the fixing members 201 and 202 are caught by these concave portions, the force required to move the steering roll 22 in the direction along the axis increases, and accordingly, the edge of the intermediate transfer belt 20 is increased. A load is applied. When the belt travels continuously, the intermediate transfer belt 20 is cracked or broken by such a load. That is, in this comparative example, the life of the intermediate transfer belt 20 is short.

  In each of the above-described embodiments, a printer is described as an example of the image forming apparatus according to the present invention. However, the image forming apparatus according to the present invention may be a copying machine or a facsimile.

  In each of the above-described embodiments, the belt member referred to in the present invention is described as an example of an intermediate transfer belt that circulates in contact with the photoreceptor roll. However, the belt member referred to in the present invention is close to the image carrier. Then, it may be circulated and moved.

  Furthermore, in each of the above-described embodiments, the belt member referred to in the present invention has been described by taking an example of an intermediate transfer belt for indirectly transferring a toner image formed on the surface of the photoreceptor roll to a sheet. The belt member referred to in the present invention may be a paper transport belt for transferring a toner image directly to a paper. Further, the belt member referred to in the present invention may be a photoreceptor belt that replaces the photoreceptor roll, a fixing belt that is used in a fixing device, or a cleaning belt that is used in a cleaning device other than a toner image being transferred. Good. The present invention is also applied to driving a belt that is stretched around a plurality of stretching rotary members in addition to the purpose of image formation.

  Moreover, in each embodiment mentioned above, although the drive roll which served as one of several tension | tensile_strength rotation members was mentioned as an example as a drive part said to this invention, the drive part said to this invention is a some drive part. It may be provided other than the tension rotating member.

  Further, in each of the above-described embodiments, an example in which an electrostatic latent image is formed on the surface of the photoreceptor roll as the image carrier referred to in the present invention and a toner image is formed by development has been described. The image carrier may be one on which a toner image is directly formed.

  In each of the above-described embodiments, a full-color image using toner of each color of Y (yellow), M (magenta), C (cyan), and K (black) is used as an image on the image carrier referred to in the present invention. As described in the example, the image on the image carrier referred to in the present invention may be a monochrome image using only K (black) toner.

  Examples of the present invention and comparative examples for the examples will be described below.

  In the examples and comparative examples, an endless belt having a thickness of 80 μm and a circumferential length of 870 mm is stretched around three stretching rolls, and a belt driving mechanism is circulated and moved at a conveying speed of 150 mm / sec. The spring member was adjusted so that a load of 6 Newtons was applied between them. Each time the endless belt traveled 10 km, the spring member was removed and the three tension rolls were reassembled. Moreover, the umbrella-shaped member and fixing member which were used in the Example are shown in FIG.

  FIG. 6 is a diagram showing an umbrella-like member and a fixing member used in the example.

  FIG. 6A is a view of the umbrella-like member 24 and the fixing member 26 as seen from the direction along the axis of the steering roll. FIG. 6B is a view of the umbrella-like member 24 and the fixing member 26 as seen from the side where the shaft portion of the steering roll extends in a direction perpendicular to the paper surface.

  In the embodiment, as the umbrella-shaped member 24, as shown in FIG. 6A, the conical portion 242 has a tapered shape having a slope of 45 ° with respect to the center line extending in the axial direction of the steering roll. It was used. Further, as shown in FIG. 6A and FIG. 6B, the fixing member 26 has a thickness and width of 2 mm, and the conical portion 242 has a surface that contacts the inclined surface of the conical portion 242. The thing according to the taper shape was used. The other umbrella-shaped member 25 and the fixing member 27 also have the same structure as the umbrella-shaped member 24 and the fixing member 26.

  Table 1 shows configurations of Examples and Comparative Examples.

  The wear rate (nm / km) in Table 1 is the wear amount (nm) with respect to the belt travel distance of 1 km at the place where the umbrella-shaped member and the fixed member are in contact. The amount of wear (nm) was measured using a contact roughness meter (Surfcom 1400A manufactured by Tokyo Seimitsu Co., Ltd.). Specifically, the difference between the concave bottom portion caused by the wear of the umbrella-shaped member with the fixing member and the smooth portions not worn at both ends of the concave portion was measured, and this difference was defined as the amount of wear of the umbrella-shaped member. Further, the length of the solid member after the fixing member was shortened due to wear with the umbrella-like member and the length of the initial solid member were measured in advance, and this difference was defined as the amount of wear of the fixing member.

The criteria for determining the quality of the belt in Table 1 are as follows.
○: No crack or break Δ: Some cracks ×: Break (Examples 1 to 4)
In Examples 1 to 4, polyimide was adopted as the material of the belt. As materials for the umbrella-shaped member and the fixing member, polyethylene and polyacetal were used in Example 1, nylon resin and polyacetal in Example 2, aluminum and polyacetal in Example 3, and aluminum and nylon resin in Example 4. In Examples 1 to 4, the wear rate of the umbrella-shaped member is as low as 6 to 22, whereas the wear rate of the fixing member is as high as 50 to 120. Therefore, even after running the belt for 200 km, the belt There were no cracks or fractures, and good results were obtained.
(Examples 5 to 8)
In Examples 5-8, it implemented on the same conditions as Examples 1-4 except having adopted polyamide imide as a material of a belt. In these Examples 5 to 8, the wear rates of the umbrella-shaped member and the fixing member were almost the same as those in Examples 1 to 4, and the belt was not cracked or broken even after running the belt for 130 km. . By changing the material of the belt from polyimide to polyamideimide, good results were obtained as a whole although cracks occurred after the belt traveled 200 km.
(Comparative Examples 1-4)
In Comparative Examples 1-4, it implemented on the same conditions as Examples 1-4 except having replaced the material of the umbrella-shaped member and fixing member which were employ | adopted in Examples 1-4, respectively. In these comparative examples 1 to 4, the wear rate of the umbrella-shaped member was as high as 50 to 125, whereas the wear rate of the fixing member was as low as 6 to 28, and the belt broke when it traveled 130 km.
(Comparative Examples 5 to 8)
In Comparative Examples 5-8, it implemented on the same conditions as Examples 5-8 except having replaced the material of the umbrella-shaped member and fixing member which were employ | adopted in Examples 5-8, respectively. In Comparative Examples 5 to 8, the wear rates of the umbrella-shaped member and the fixing member were almost the same as those in Comparative Examples 1 to 4, and the belt broke when it traveled 130 km.

  As described above, when an umbrella-shaped member made of a material having a low wear rate and a fixing member made of a material having a higher wear rate than the material of the umbrella-shaped member are used, cracks and breakage of the belt can be generated for a long time. It was confirmed that it was prevented over time.

DESCRIPTION OF SYMBOLS 1 Printer 2,200 Belt drive device 10Y, 10M, 10C, 10K Image formation part 11Y, 11M, 11C, 11K Photoconductor roll 12Y, 12M, 12C, 12K Charging device 13Y, 13M, 13C, 13K Exposure device 14Y, 14M, 14C, 14K Developing devices 15Y, 15M, 15C, 15K Primary transfer roll 16 Secondary transfer roll 17 Fixing unit 18 Control unit 20 Intermediate transfer belt 21 Drive roll 22 Steering roll 22a Shaft unit 23 Idler roll 24, 25 Umbrella member 26, 27, 201, 202 Fixing member 31, 32 Spring member 241,251 Cylindrical portion 242,252 Conical portion

Claims (6)

A band member wound in a tubular shape;
A plurality of tension rotating members rotating in contact with the inner peripheral surface of the band member, wherein the band member is stretched between each other and the band member circulates between each other;
A drive unit that drives the belt member to circulate and move between the stretching rotary members;
A movable member that also serves as a part of the plurality of tension rotating members, and is movable relative to other tension rotating members while maintaining the tension of the belt member;
Umbrella-shaped members provided at both ends of the moving member with the tip facing outward,
A band driving mechanism comprising: a fixing member that is in contact with the umbrella-shaped surface of the umbrella-shaped member and has a fixed position, and has a higher wearability than the wearability of the umbrella-shaped member.   The said fixing member has a member shape which hits the umbrella-shaped surface of the said umbrella-shaped member with a surface, and a surface shape is maintained even if the contacted surface is worn out. Band drive mechanism.   The belt drive mechanism according to claim 1 or 2, wherein the drive unit also serves as at least one of the stretching rotary members.   The belt drive according to any one of claims 1 to 3, wherein the driving unit also serves as another tension rotating member excluding the moving member of the tension rotating member. mechanism. A band member wound in a tubular shape;
A plurality of tension rotating members rotating in contact with the inner peripheral surface of the band member, wherein the band member is stretched between each other and the band member circulates between each other;
A drive unit that drives the belt member to circulate and move between the stretching rotary members;
A movable member that also serves as a part of the plurality of tension rotating members, and is movable relative to other tension rotating members while maintaining the tension of the belt member;
Umbrella-shaped members provided at both ends of the moving member with the tip facing outward,
An image forming apparatus comprising: a fixing member that is in contact with the umbrella-shaped surface of the umbrella-shaped member and has a fixed position, and has a wear property higher than that of the umbrella-shaped member. An image carrier for holding an image on the surface;
An image forming unit that forms an image on the surface of the image carrier,
The belt member circulates and moves on a circulation path that is close to or in contact with the image carrier at a predetermined position.
The image forming apparatus according to claim 5, further comprising a transfer unit that transfers an image on the image holding member to a surface of the belt member and / or a surface of a recording medium conveyed by the belt member.

Images