JP6083409B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus including a belt that is stretched between a plurality of rollers.

  2. Description of the Related Art Conventionally, an image forming apparatus that forms an image on a recording sheet such as a sheet is known that includes a belt such as a conveyance belt that is stretched between a plurality of rollers. In Patent Document 1, a convex portion is provided on the back surface of the belt along the circumferential direction thereof, and the roller is provided with a concave portion that can be loosely fitted to the convex portion, and a flange that projects radially from the end portion of the roller. A configuration is disclosed in which a belt is hung on a roller so that a convex portion and a concave portion are engaged with each other in a state where an edge of the belt is adjacent to a flange.

JP 2008-170478 A

  By the way, in the prior art, when the edge of the belt comes into contact with the flange, the end of the belt may be deformed by friction.

  The present invention has been made in view of the above background, and an object thereof is to provide an image forming apparatus capable of suppressing the deviation and deformation of a belt.

In order to achieve the above-described object, an image forming apparatus according to the present invention is disposed on one side of a rotation axis direction of a belt spanned between a plurality of rollers and one of the plurality of rollers, An outer regulating portion facing the belt end surface so that a belt end surface, which is an end surface of the belt in the rotation axis direction, can come into contact therewith.
The belt has a convex portion that protrudes from a position spaced from the belt end surface at a predetermined interval on the inner peripheral surface of the belt and continuously extends along the circumferential direction of the belt.
The outer regulating portion protrudes inward in the rotational axis direction so as to face an outer end surface that is an end surface on the outer side in the rotational axis direction of the convex portion, and continuously extends along the rotational direction of the one roller. It has an auxiliary regulation part.
The protrusion amount of the auxiliary restricting portion is smaller than the predetermined interval.

  According to such a configuration, the deviation of the belt can be suppressed by the belt end surface being in contact with the outer regulating portion. Further, when the belt end surface comes into contact with the outer regulating portion and the end portion of the belt tends to be deformed, further deformation of the belt can be suppressed by the convex portion coming into contact with the auxiliary regulating portion.

  The image forming apparatus described above is disposed on one side in the rotation axis direction of the one roller, and the inner regulation that faces the inner end surface so that the inner end surface, which is the end surface on the inner side in the rotation axis direction, of the convex portion can come into contact therewith. It can be set as the structure provided with the part.

  According to this, the deviation of the belt can be suppressed on both sides in the rotation axis direction. In addition, since it is sufficient to arrange a pair of the outer regulating portion and the inner regulating portion only on one side in the rotation axis direction of one roller, it is possible to simplify the belt deviation restraining structure.

  In the image forming apparatus described above, the length along the belt of the portion where the belt end surface and the outer regulating portion overlap as viewed from the rotation axis direction is the portion of the portion where the inner end surface and the inner regulating portion overlap. The length may be longer than the length along the belt.

  According to this, in the circumferential direction of the belt, it is possible to ensure a contact area between the belt end surface and the outer regulating portion. As a result, the force applied to the belt end surface can be dispersed, so that deformation of the end portion of the belt can be suppressed.

  Further, in the above-described image forming apparatus, the outer regulation portion may be arranged on both sides in the rotation axis direction of the one roller.

  According to this, the deviation of the belt can be suppressed on both sides in the rotation axis direction. In addition, when the inner restricting portion is not provided and the outer restricting portions are arranged on both sides in the rotation axis direction of the roller, the force for correcting the deviation when the belt is closer to one side or the other side in the rotation axis direction is obtained. Since it becomes uniform, the rotation of the belt can be stabilized.

  In the above-described image forming apparatus, the portion of the auxiliary restricting portion with which the outer end face can come into contact is configured to approach the inner side in the rotational axis direction from the inner side in the radial direction of the one roller. can do.

  According to this, when a convex part contact | abuts to an auxiliary | assistant control part, since the force which goes to a radial inside acts on a convex part, it can suppress that a convex part deform | transforms toward a radial direction outer side.

  In the above-described image forming apparatus, the length of the convex portion in the rotational axis direction is the length in the radial direction of the one roller at the portion where the auxiliary regulating portion and the convex portion overlap as viewed from the rotational axis direction. It can be set as a structure longer than this.

  According to this, since a convex part becomes long in a rotating shaft direction, a deformation | transformation of the edge part of a belt when a convex part contact | abuts to an auxiliary | assistant control part can be suppressed.

  In the above-described image forming apparatus, the plurality of rollers include a driving roller that applies a driving force to rotate the belt, and a driven roller that is driven to rotate by the rotation of the belt, and the one roller includes It can be set as the structure which is a driven roller.

  According to this, an outer side regulation part and an auxiliary regulation part can be functioned in the part by which a belt is pulled by a drive roller.

  In the image forming apparatus described above, the friction coefficient of the portion of the driven roller that contacts the belt may be smaller than the friction coefficient of the portion of the drive roller that contacts the belt.

  According to this, it is possible to reduce the resistance when the belt returns to the original position after the belt end surface comes into contact with the outer regulating portion or after the convex portion comes into contact with the auxiliary regulating portion. Thereby, deformation of the belt can be suppressed, and wear of the belt end surface and the convex portion can be suppressed.

  The above-described image forming apparatus is disposed to face the belt, and is disposed with the belt between the image carrier that carries a developer image and the image carrier, and the image carrier carries the image carrier. A plurality of transfer units for transferring the developer image can be provided.

  According to this, since the deviation of the belt can be suppressed, it is possible to suppress the displacement of the developer image when the developer image is transferred from each image carrier.

  The above-described image forming apparatus may include a sheet supply unit that supplies a recording sheet onto the belt.

  According to this, since the deviation of the belt can be suppressed, it is possible to suppress the skew and displacement of the recording sheet conveyed on the belt.

  In the above-described image forming apparatus, the belt may have a Young's modulus of 2000 MPa or less.

  In the above-described image forming apparatus, the belt end face may have a thickness of 0.13 mm or more.

  According to the present invention, the deviation and deformation of the belt can be suppressed.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment. It is an enlarged view of a transfer unit. It is sectional drawing of the one side of the rotating shaft direction of the driven roller equivalent to the XX cross section of FIG. FIG. 4 is an enlarged view of FIG. 3. It is a figure which shows the state which the belt end surface of the conveyance belt contact | abutted to the outer side regulation part. It is a figure which shows the state which the inner side end surface of the convex part of a conveyance belt contact | abutted to the inner side control part. It is a figure which shows the state which the outer side end surface of the convex part of a conveyance belt contact | abutted to the auxiliary | assistant control part. It is figure (a), (b) which shows the modification of an auxiliary | assistant control part. FIG. 10 is a cross-sectional view of the vicinity of a driven roller of an image forming apparatus according to a modification.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described in detail with reference to the drawings as appropriate. In the following description, first, a schematic configuration of the image forming apparatus according to the embodiment will be described, and then a detailed configuration around the belt will be described. In the following description, the direction will be described with reference to the user who uses the image forming apparatus. Specifically, the left side of FIG. 1 as viewed from the user is “front”, the right side of FIG. 1 as viewed from the user is “rear”, and the front side of FIG. 1 is “right”. 1 is defined as “left”, and the top and bottom in FIG.

As shown in FIG. 1, a color printer 1 as an example of an image forming apparatus mainly includes a sheet feeding unit 3 as an example of a sheet supply unit and an image forming unit 4 in a main body housing 2. .
The main body housing 2 is provided on the upper side of the box-shaped main body frame 21 having an opening in the upper portion and the main body frame 21, and is rotated up and down around a rear rotation shaft (not shown) to thereby An upper cover 22 that mainly opens and closes the opening is mainly provided.

  The paper feed unit 3 is provided at a lower portion in the main body housing 2, and mainly includes a paper feed tray 31 that stores paper S as an example of a recording sheet, and a supply mechanism 32 that supplies the paper S to the image forming unit 4. In preparation. The paper feed unit 3 separates the paper S in the paper feed tray 31 one by one by the supply mechanism 32 and supplies the paper S onto a later-described transport belt 73 of the image forming unit 4.

  The image forming unit 4 mainly includes four exposure units 5, four process cartridges 6, a transfer unit 7, and a fixing device 8.

  The exposure unit 5 includes a plurality of LEDs (Light Emitting Diodes) (not shown) arranged on the lower end of the photosensitive drum 51 so as to face each other. The exposure unit 5 exposes the surface of the photosensitive drum 51 by blinking the LED based on the image data. The exposure unit 5 is held by the upper cover 22 via the holding unit 24, and moves together with the upper cover 22 by moving the upper cover 22 away from the photosensitive drum 51.

  The process cartridge 6 is arranged side by side between the upper cover 22 and the paper feed tray 31 and is detachable from the main body frame 21 in a state where the upper cover 22 is opened. Each process cartridge 6 includes a drum unit 6A and a developing unit 6B. The drum unit 6A mainly includes a photosensitive drum 51 as an example of an image carrier and a charger 52. The developing unit 6B is configured to be detachable from the drum unit 6A, and mainly includes a developing roller 61, a supply roller 62, a layer thickness regulating blade 63, and a storage portion 64 that stores toner. ing. The toner in the storage portion 64 is supplied to the developing roller 61 by the supply roller 62 and is carried on the developing roller 61 after being regulated to a certain thickness between the developing roller 61 and the layer thickness regulating blade 63. .

  The transfer unit 7 is provided between the paper feed tray 31 and the process cartridge 6, and includes a driving roller 71, a driven roller 72, a conveyance belt 73 as an example of a belt, and a transfer roller 74 as an example of a transfer device. It is mainly equipped with. The conveying belt 73 is stretched between a driving roller 71 and a driven roller 72 as an example of a plurality of rollers, and the respective photosensitive drums 51 are arranged to face each other on the outer surface. Four transfer rollers 74 are provided corresponding to the photosensitive drums 51, and are arranged with the conveyance belt 73 between the corresponding photosensitive drums 51.

  The fixing device 8 is provided behind the process cartridge 6 and the transfer unit 7 and mainly includes a heating roller 81 and a pressure roller 82.

  The image forming unit 4 forms the electrostatic latent image on the photosensitive drum 51 by charging the surface of the photosensitive drum 51 with the charger 52 and exposing with the exposure unit 5. When the toner carried on the developing roller 61 is supplied, the photosensitive drum 51 carries on its surface a toner image as an example of a developer image in which the electrostatic latent image is visualized. . Thereafter, the sheet S supplied from the sheet feeding unit 3 onto the conveyance belt 73 is conveyed between the photosensitive drum 51 and the transfer roller 74 to which the transfer bias is applied, so that the transfer roller 74 is moved to the photosensitive drum. The toner image carried by 51 is transferred to the paper S. Then, the sheet S on which the toner image is transferred is conveyed between the heating roller 81 and the pressure roller 82, so that the toner image is thermally fixed on the sheet S.

  The paper S on which the toner image has been thermally fixed is discharged onto a paper discharge tray 23 provided on the upper surface of the upper cover 22 by a transport roller 91 and a discharge roller 92.

  As shown in FIG. 2, the transfer unit 7 further includes a regulating member 75 in addition to the driving roller 71, the driven roller 72, the transport belt 73, and the like. In the following description, the rotation axis direction of the driving roller 71 and the driven roller 72 corresponding to the left and right direction is simply referred to as “rotation axis direction”, and the radial direction of the driven roller 72 is simply referred to as “radial direction”.

  The driving roller 71 is a roller that applies a driving force to rotate the conveyance belt 73, and mainly includes a shaft 71A and a driving roller main body 71B. The driving roller 71 is driven to rotate when a driving force is input from a motor (not shown) provided in the main body housing 2.

  The driven roller 72 mainly has a shaft 72A and a driven roller main body 72B. The driven roller 72 is driven to rotate by the rotation of the conveying belt 73 to which the driving force is input from the driving roller 71. Further, the driven roller 72 is urged toward the front side, which is a direction in which the shaft 72A is separated from the drive roller 71 by an urging member 76 such as a coil spring. Thereby, when the conveyance belt 73 is bridged between the drive roller 71 and the driven roller 72, tension is applied to the conveyance belt 73.

  The drive roller main body 71B and the driven roller main body 72B are made of a metal material such as aluminum formed in a substantially cylindrical shape, and the outer peripheral surfaces 71C and 72C are portions that come into contact with the inner peripheral surface 111 of the conveyor belt 73. Yes. The outer peripheral surface 71 </ b> C of the drive roller 71 is coated with a paint for increasing the friction coefficient. In other words, the outer peripheral surface 72C of the driven roller 72 is not coated with a paint for increasing the coefficient of friction. Thereby, the friction coefficient of the outer peripheral surface 72 </ b> C of the driven roller 72 is smaller than the friction coefficient of the outer peripheral surface 71 </ b> C of the drive roller 71.

  The conveyor belt 73 is an endless belt that is formed by cutting a belt base material formed in a tube shape with a predetermined width and has no joints in the circumferential direction. The conveyance belt 73 can have a configuration in which the Young's modulus with respect to the tensile force in the circumferential direction is, for example, 2000 MPa or less. Moreover, the Young's modulus of the conveyance belt 73 can be set as the structure which is 1500 Mpa or more as an example, Preferably it is 1600 Mpa or more. As shown in FIG. 3, the conveyance belt 73 includes a belt main body 110 and a convex portion 120 protruding from the inner peripheral surface 111 of the belt main body 110.

  The width of the belt main body 110 in the rotation axis direction is larger than the width of the maximum size image that can be formed on the paper S by the color printer 1. For example, the thickness of the belt end surface 113 (the thickness of the belt main body 110), which is the end surface of the belt main body 110 in the rotation axis direction, may be 0.13 mm or more. Moreover, the thickness of the belt end surface 113 can be set as 0.15 mm or less as an example.

  The convex portion 120 protrudes in a direction orthogonal to the inner peripheral surface 111 from a position at a predetermined distance D1 from the belt end surface 113 in the inner peripheral surface 111 of the belt main body 110, and extends along the circumferential direction of the transport belt 73. Extend continuously. In the present embodiment, the convex portion 120 is provided only on the left side of the belt main body 110. Moreover, in this embodiment, the cross-sectional shape of the convex part 120 is substantially rectangular shape. As an example, the distance D1 is 0.35 mm, the length L1 of the convex portion 120 in the rotational axis direction is 4 mm, and the length L2 of the convex portion 120 in the direction orthogonal to the rotational axis direction is 1.5 mm. It can be set as the structure which is. In the following description, the end surface on the outer side in the rotation axis direction of the convex portion 120 is referred to as “outer end surface 122”, and the end surface on the inner side in the rotation axis direction of the convex portion 120 is referred to as “inner end surface 123”.

  The restricting member 75 includes an outer restricting member 200 and an inner restricting member 300, and is disposed on one side of the driven roller 72 in the rotation axis direction, specifically, on the left side of the driven roller main body 72B. In the present embodiment, only one restricting member 75 is disposed on the left side of the driven roller body 72B, and is not disposed on the right side of the driven roller body 72B and on both sides of the drive roller body 71B.

  The outer regulating member 200 mainly includes a substantially cylindrical shaft engaging portion 210 and an outer regulating portion 220 formed around the shaft engaging portion 210. Further, the inner regulating member 300 mainly includes a substantially cylindrical connecting portion 310 and an inner regulating portion 320 formed around the connecting portion 310. The outer restriction member 200 and the inner restriction member 300 are integrated into the restriction member 75 by press-fitting the shaft engaging portion 210 inside the connecting portion 310. Then, by pressing the end of the shaft 72 </ b> A of the driven roller 72 inside the shaft engaging portion 210, the regulating member 75 is attached to the driven roller 72 and can be rotated integrally with the driven roller 72.

The outer restricting portion 220 is a substantially disk-shaped portion that protrudes radially outward from the outer periphery of the shaft engaging portion 210, and is formed with a diameter larger than the diameter of the driven roller body 72B. As shown in an enlarged view in FIG. 4, the outer regulation portion 220 is directed inward in the rotational axis direction with respect to the first outer regulation surface 221 facing the belt end surface 113 of the conveyor belt 73 and the first outer regulation surface 221. It mainly has a protruding auxiliary restricting portion 222.
The first outer regulating surface 221 is a surface substantially parallel to the radial direction with which the belt end surface 113 can come into contact.

  The auxiliary restricting portion 222 protrudes inward in the rotational axis direction so as to face the inner portion in the radial direction of the outer end surface 122 of the convex portion 120, and continues along the rotational direction of the driven roller 72 (the restricting member 75). It extends. The protrusion amount D2 with respect to the first outer restriction surface 221 of the auxiliary restriction portion 222 is smaller than the interval D1 from the belt end surface 113 to the outer end surface 122 of the convex portion 120 in the rotation axis direction. As an example, the protrusion amount D2 can be configured to be 1/3 to 1/2 of the interval D1, and when the interval D1 is 0.35 mm, the protrusion amount D2 is configured to be 0.15 mm. be able to.

  The auxiliary restricting portion 222 has a second outer restricting surface 223 that faces the outer end surface 122 of the convex portion 120. Similar to the first outer regulating surface 221, the second outer regulating surface 223 is a surface substantially parallel to the radial direction. In the present embodiment, the length L1 of the convex portion 120 in the rotational axis direction is longer than the length L3 in the radial direction of the portion where the auxiliary restricting portion 222 and the convex portion 120 overlap as viewed from the rotational axis direction. The length L3 is configured to be greater than the thickness of the belt end surface 113. As an example, when the length L1 is 4 mm, the length L3 may be 1.5 mm.

  The inner regulating portion 320 is a portion provided so as to protrude radially outward from the outer periphery of the coupling portion 310, and is formed with a diameter that is substantially the same as the diameter of the driven roller body 72B. In addition, the inner regulating portion 320 is disposed so as to face the outer regulating portion 220 in the rotation axis direction and sandwich the convex portion 120 of the transport belt 73 between the outer regulating portion 220. The inner side regulation part 320 mainly has the inner side regulation surface 321 which opposes the inner side end surface 123 of the convex part 120, and the belt support surface 322 which is a surface of a radial direction outer side. The inner regulation surface 321 is a surface substantially parallel to the radial direction with which the inner end surface 123 can abut. The belt support surface 322 is a surface that supports the conveyor belt 73 from the inside together with the outer peripheral surface 72C of the driven roller body 72B.

  As shown in FIG. 2, when viewed from the rotation axis direction, the length L4 along the transport belt 73 where the outer regulating portion 220 and the belt end surface 113 of the belt main body 110 overlap each other is the inner regulating portion 320 and the convex portion 120. Is longer than a length L5 along the conveyor belt 73 where the inner end surface 123 of the upper part overlaps. Thereby, in the circumferential direction of the conveyance belt 73, an area where the belt end surface 113 and the outer regulating portion 220 that can contact the belt end surface 113 can be contacted is ensured.

  Each of the outer regulating member 200 and the inner regulating member 300 described above can be molded by injecting a molten resin into a mold having a cavity corresponding to its shape and hardening the resin. As shown in FIG. 3, in the present embodiment, the outer regulating member 200 and the inner regulating member 300 each have no overlapping portion when viewed from the rotation axis direction (because there is no undercut shape). It can be pulled out along the rotation axis direction. Thereby, a parting line cannot be formed on the first outer regulating surface 221, the second outer regulating surface 223, and the inner regulating surface 321 indicated by the reference numerals in FIG.

Next, the effect of this embodiment comprised as mentioned above is demonstrated.
As shown in FIG. 4, normally, between the first outer regulating surface 221 of the outer regulating portion 220 and the belt end surface 113 of the conveying belt 73, and the inner regulating surface 321 of the inner regulating portion 320 and the convex portion of the conveying belt 73. There is a gap between the inner end surface 123 of 120 and the conveyor belt 73 rotates with a gap in a state where no deviation occurs.

  As shown in FIG. 5, when the conveyor belt 73 moves to the left, the belt end surface 113 comes into contact with the first outer regulation surface 221 of the outer regulation unit 220. Thereby, the deviation to the left side of the conveyance belt 73 can be suppressed. As shown in FIG. 6, when the conveyor belt 73 moves to the right, the inner end surface 123 of the convex portion 120 comes into contact with the inner restriction surface 321 of the inner restriction portion 320. Thereby, the deviation | shift to the right side of the conveyance belt 73 can be suppressed. In other words, in the present embodiment, since the regulating member 75 includes the outer regulating portion 220 and the inner regulating portion 320, the shift of the conveyor belt 73 can be suppressed on both the left and right sides.

  Since the deviation of the conveyance belt 73 can be suppressed in this way, the skew and misalignment of the sheet S conveyed on the conveyance belt 73 can be suppressed. Further, the color printer 1 including a plurality of sets of the photosensitive drums 51 and the transfer rollers 74 by suppressing the skew of the sheet S conveyed on the conveyance belt 73 and the positional deviation thereof can be suppressed. When the toner images are transferred from the respective photosensitive drums 51 to the paper S, the positional deviation (color deviation) of the toner images of the respective colors can be suppressed.

  Further, since the restriction member 75 includes both the outer restriction part 220 and the inner restriction part 320, it is possible to suppress the deviation even when the transport belt 73 moves to the left or right. In the present embodiment, the regulating member 75 is disposed only on the left side of the driven roller body 72B, and is not disposed on the right side of the driven roller body 72B. Thereby, compared with the case where the member which controls the deviation | shift of a belt is provided in the both sides of a rotating shaft direction, the deviation | shift deviation suppression structure of a belt can be simplified. Further, since the convex portion 120 is provided only on the left side of the conveyance belt 73 and not on the right side, the structure of the conveyance belt 73 can be simplified.

  When the belt end surface 113 shown in FIG. 5 is in contact with the first outer regulating surface 221 of the outer regulating portion 220 and a force is applied to move the conveying belt 73 to the left, the belt end surface 113 is shown in FIG. As described above, the end portion of the conveyor belt 73 may be deformed so as to bend outward in the radial direction. However, in this embodiment, when the end portion of the conveyance belt 73 is deformed, the outer end surface 122 of the convex portion 120 abuts on the second outer restriction surface 223 of the auxiliary restriction portion 222, so that the conveyance belt 73 is moved to the left. Further movement can be restricted. Thereby, the further deformation | transformation of the edge part of the conveyance belt 73 can be suppressed.

  In the present embodiment, as shown in FIG. 2, the length L4 of the portion where the belt end surface 113 and the outer regulating portion 220 overlap is greater than the length L5 of the portion where the inner end surface 123 and the inner regulating portion 320 overlap. Therefore, the contact area between the belt end surface 113 and the outer regulating portion 220 can be ensured in the circumferential direction of the conveyor belt 73. Thereby, since the force applied to the belt end surface 113 can be dispersed, the deformation of the end portion of the conveyor belt 73 can be suppressed.

  In the present embodiment, as shown in FIG. 4, the length L1 of the convex portion 120 is longer than the length L3 of the portion where the auxiliary restricting portion 222 and the convex portion 120 overlap with each other. When 120 abuts on the auxiliary restricting portion 222, the convex portion 120 serves as a reinforcement of the belt main body 110, and deformation of a portion overlapping the convex portion 120 of the belt main body 110 can be suppressed. Also by this, the deformation of the end portion of the conveyance belt 73 can be suppressed.

  In this embodiment, since the friction coefficient of the outer peripheral surface 72C of the driven roller 72 is smaller than the friction coefficient of the outer peripheral surface 71C of the driving roller 71, after the belt end surface 113 comes into contact with the outer restricting portion 220, the convex portion It is possible to reduce the resistance when the conveying belt 73 returns to the original position after the 120 abuts on the inner regulating portion 320 and the auxiliary regulating portion 222. Thereby, deformation of the conveyor belt 73 can be suppressed, and wear of the belt end surface 113 and the convex portion 120 can be suppressed.

  In addition, since there are no parting lines on the first outer regulating surface 221, the second outer regulating surface 223, and the inner regulating surface 321, the sliding resistance when the transport belt 73 comes into contact with these can be reduced. Also by this, deformation of the conveyance belt 73 can be suppressed, and wear of the belt end surface 113 and the convex portion 120 can be suppressed.

  Further, in the configuration in which the driving roller 71 and the driven roller 72 are provided as a plurality of rollers, the regulating member 75 is disposed on one side of the driven roller 72 in the rotation axis direction, so that the conveying belt 73 is pulled by the driving roller 71. That is, the outer restricting portion 220 and the auxiliary restricting portion 222 can be made to function in a portion (range Y in FIG. 2) that is upstream of the driving roller 71 of the transport belt 73 and downstream of the driven roller 72. it can. The portion in the range of Y in FIG. 2 is a portion where the conveyor belt 73 is stretched without loosening, so that the conveyor belt 73 moves to the left when the portion abuts against the outer restricting portion 220 or the auxiliary restricting portion 222. The force which is going to be received can be received effectively and the deviation and deformation | transformation of the conveyance belt 73 can be suppressed effectively.

  Although the embodiment has been described above, the present invention is not limited to the embodiment. About a concrete structure, it can change suitably in the range which does not deviate from the meaning of invention as follows.

  In the above embodiment, as shown in FIG. 4, the second outer restriction surface 223 of the auxiliary restriction portion 222 is a surface substantially parallel to the radial direction, but is not limited to this. For example, as shown in FIG. 8A, the second outer regulating surface 224, which is a portion with which the outer end surface 122 of the auxiliary regulating portion 222 can come into contact, extends from the radially inner side of the driven roller 72 to the outer side in a sectional view. The surface may be inclined so as to form a shape that approaches the inside in the rotation axis direction as it goes. According to this, as shown in FIG. 8B, when the outer end face 122 of the convex portion 120 abuts on the auxiliary restricting portion 222, a force directed radially inward indicated by an arrow acts on the convex portion 120. It is possible to suppress the convex portion 120 from being deformed toward the radially outer side. Thereby, it can suppress that the convex part 120 rides on the outer periphery of the auxiliary | assistant control part 222. FIG.

  In the said embodiment, although the control member 75 was the structure provided with both the outer side control part 220 and the inner side control part 320, it is not limited to this, For example, the structure which is not provided with the inner side control part 320 may be sufficient. For example, as shown in FIG. 9, the restricting member 75A mainly includes a shaft engaging portion 210 and an outer restricting portion 220 having an auxiliary restricting portion 222, and the rotational axis direction of the driven roller 72 (driven roller main body 72B). The structure arrange | positioned at the both sides of each may be sufficient. In this case, the convex portions 120 of the conveyor belt 73 are provided on the left and right sides of the conveyor belt 73, respectively. According to this, when the conveyor belt 73 moves to the left, the left belt end surface 113 abuts on the left outer regulating portion 220, so that the deviation of the conveyor belt 73 toward the left side can be suppressed. When the belt 73 moves to the right, the right belt end surface 113 abuts on the right outer side restricting portion 220 so that the belt belt 73 can be prevented from shifting to the right side. It can be suppressed on both sides. In addition, since the symmetrical regulating members 75A are arranged on both sides of the driven roller 72, the force for correcting the deviation when the conveying belt 73 approaches the left side or the right side becomes uniform. The rotation of 73 can be stabilized.

  In the embodiment described above, the regulating member 75 is disposed on the driven roller 72, but is not limited thereto, and may be disposed on the driving roller 71, for example. In other words, in the present invention, “one of the plurality of rollers” may be a driving roller instead of a driven roller.

  In the above embodiment, the conveyance belt 73 is stretched between the driving roller 71 and the driven roller 72, that is, between the two rollers. However, the present invention is not limited to this. For example, the conveyance belt 73 includes three or more rollers. It may be bridged between them.

  In the above-described embodiment, the conveyance belt 73 is exemplified as the belt, but is not limited thereto, and may be, for example, an intermediate transfer belt or a photosensitive belt provided in the image forming apparatus. That is, the present invention is not limited to a belt that conveys a sheet on which a toner image is formed, and may be configured such that a toner image is formed on the belt. Moreover, in the said embodiment, although the endless belt which has no joint in the circumferential direction was illustrated, it is not limited to this, For example, the belt (belt with a joint) which connected the end and was endless may be sufficient. . Moreover, in the said embodiment, although the cross-sectional shape of the convex part 120 became substantially rectangular shape, it is not limited to this, For example, it may become substantially triangular shape, substantially trapezoid shape, etc.

  In the above-described embodiment, the photosensitive drum 51 is exemplified as the image carrier. However, the image carrier is not limited thereto, and may be, for example, an intermediate transfer member or a belt-like image carrier. In the embodiment, the transfer roller 74 is exemplified as the transfer device. However, the transfer roller 74 is not limited to this. For example, a transfer plate configured in a plate shape, a non-contact transfer device that does not contact the belt, or the like may be used. Good.

  In the above-described embodiment, the color printer 1 having a plurality of sets of image carriers and transfer units and capable of forming a color image is exemplified as the image forming apparatus. However, the present invention is not limited to this. The printer may include only one set and can form only a monochrome image. The image forming apparatus is not limited to an electrophotographic printer such as a laser printer, and may be, for example, an ink jet printer. In other words, an image may be formed on a sheet conveyed on the belt by an inkjet head facing the belt. Further, the image forming apparatus is not limited to a printer, and may be, for example, a copying machine or a multifunction machine including a document reading device such as a flat bed scanner.

  In the above-described embodiment, the sheet S such as so-called plain paper is exemplified as the recording sheet. However, the recording sheet is not limited thereto, and may be, for example, an OHP sheet.

DESCRIPTION OF SYMBOLS 1 Color printer 3 Paper feed part 51 Photosensitive drum 71 Driving roller 71C Outer peripheral surface 72 Driven roller 72C Outer peripheral surface 73 Conveying belt 74 Transfer roller 75 Restriction member 110 Belt main body 111 Inner peripheral surface 113 Belt end surface 120 Convex part 122 Outer end surface 123 Inner side End face 220 Outer restricting portion 222 Auxiliary restricting portion 320 Inner restricting portion S Paper

Claims (12)

A belt stretched between a plurality of rollers;
An outer regulating portion that is disposed on one side of the rotation axis direction of one of the plurality of rollers and faces the belt end surface so that a belt end surface that is an end surface of the belt in the rotation axis direction can come into contact therewith; With
The belt protrudes from a position at a predetermined interval from the belt end surface among the inner peripheral surface of the belt, and has a convex portion that extends continuously along the circumferential direction of the belt,
The outer regulating portion protrudes inward in the rotational axis direction so as to face an outer end surface that is an end surface on the outer side in the rotational axis direction of the convex portion, and continuously extends along the rotational direction of the one roller. Has an auxiliary regulation part,
The image forming apparatus according to claim 1, wherein a protrusion amount of the auxiliary restricting portion is smaller than the predetermined interval.   An inner regulating portion that is disposed on one side of the rotation axis direction of the one roller and that is opposed to the inner end surface so that an inner end surface that is an end surface on the inner side in the rotation axis direction of the convex portion can be contacted. The image forming apparatus according to claim 1.   When viewed from the rotational axis direction, the length along the belt where the belt end surface and the outer regulating portion overlap is longer than the length along the belt where the inner end surface and the inner regulating portion overlap. The image forming apparatus according to claim 2, wherein the image forming apparatus is longer.   The image forming apparatus according to claim 1, wherein the outer restricting portions are respectively disposed on both sides in a rotation axis direction of the one roller.   The portion of the auxiliary restricting portion with which the outer end face can come into contact has a shape that approaches the inner side in the rotational axis direction from the radially inner side to the outer side of the one roller. The image forming apparatus according to claim 4.   The length of the convex portion in the rotational axis direction is longer than the length in the radial direction of the one roller at the portion where the auxiliary restricting portion and the convex portion overlap when viewed from the rotational axis direction. The image forming apparatus according to any one of claims 1 to 5. The plurality of rollers include a driving roller that applies a driving force to rotate the belt, and a driven roller that is driven to rotate by the rotation of the belt,
The image forming apparatus according to claim 1, wherein the one roller is the driven roller.   The image forming apparatus according to claim 7, wherein a friction coefficient of a portion of the driven roller contacting the belt is smaller than a friction coefficient of a portion of the driving roller contacting the belt. An image carrier disposed opposite to the belt and carrying a developer image;
9. The apparatus according to claim 1, further comprising: a plurality of transfer units arranged with the belt sandwiched between the image carrier and transferring a developer image carried by the image carrier. The image forming apparatus according to any one of the above.   The image forming apparatus according to claim 1, further comprising a sheet supply unit that supplies a recording sheet onto the belt.   The image forming apparatus according to any one of claims 1 to 10, wherein the belt has a Young's modulus of 2000 MPa or less.   The image forming apparatus according to claim 1, wherein a thickness of the belt end surface is 0.13 mm or more.

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