JP2010122554A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus surely positioning a belt unit by surely suppressing lift of an edge of the belt unit. <P>SOLUTION: The belt unit (conveyance belt unit 70) includes a handle provided at one end side of a frame, a supporting shaft portion 75E provided at the other end side of the frame, and a frame-side engaging portion (positioning projection 75F) provided between the supporting shaft portion 75E and the handle. An apparatus body 10 includes a supporting surface 111 supporting the supporting shaft portion 75E turnably, a body-side engaging portion (slot 112) fit to the frame-side engaging portion that moves in circular-arc locus centering the supporting shaft portion 75E, and a pressing portion 113 pressing the lift of the supporting shaft portion 75E by contacting a contact portion 75G nearer to the other end side than the supporting shaft portion 75E when the frame-side engaging portion and the body-side engaging portion are fit to each other. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus in which a belt unit is positioned and fixed with respect to an apparatus main body.

  2. Description of the Related Art Conventionally, an image forming apparatus that includes a belt unit that transports a sheet and an apparatus main body to which the belt unit is mounted is known (see Patent Document 1). Specifically, the belt unit in this technology is provided with a handle provided on one end side in the belt tensioning direction, and is provided on the other end side and is rotatably supported by the apparatus main body when the belt unit is mounted. A support shaft portion and a positioning pin provided between the support shaft portion and the handle and projecting downward are provided.

  Further, the apparatus main body is formed with a U-shaped support groove that opens upward to rotatably support the support shaft portion, and a positioning hole that fits with the positioning pin. Further, the support shaft portion of the belt unit is formed with an engagement piece that protrudes toward the handle side, and a lateral engagement groove that opens into the support groove is formed on the side portion of the support groove of the apparatus body. Is formed.

  In this technique, after the user grasps the handle and inserts the support shaft portion of the belt unit into the support groove, the belt unit is rotated around the support shaft portion, thereby engaging the engagement piece with the engagement groove. The belt unit is fixed to the apparatus main body by fitting the positioning pins into the positioning holes.

JP 2007-101728 A

  However, in the above-described technique, when the positioning pin is caught on the edge of the positioning hole before the engaging piece engages with the engaging groove, the belt unit rotates around the hooked portion, There was a problem that the tip of the belt unit floated and could not be positioned.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that can reliably perform positioning by reliably suppressing the floating of the tip of a belt unit.

  The present invention that solves the above-described problems includes a belt unit having a belt stretched between a pair of rollers and a frame that rotatably supports the pair of rollers, and an apparatus main body to which the belt unit is mounted. The belt unit includes a handle provided on one end side of the frame in the tensioning direction of the belt, and a handle provided on the other end side of the frame in the tensioning direction. A support shaft that is rotatably supported by the apparatus main body when mounted, and is provided between the support shaft and the handle, and is formed in a convex shape or a concave shape for positioning the belt unit. A frame-side engagement portion, and the apparatus main body has a support surface that rotatably supports the support shaft portion, and an arc shape centered on the support shaft portion. A main body side engaging portion having a concave and convex shape opposite to that of the frame side engaging portion, and the frame side engaging portion and the main body side so as to be fitted to the frame side engaging portion moving in a trace A pressing portion that abuts against the support shaft portion or the contact portion on the other end side of the support shaft portion and holds the support shaft portion from rising when the engagement portion is fitted. Features.

  According to the present invention, for example, in a state where the convex frame side engaging portion is caught by the edge of the concave main body side engaging portion and is not completely fitted, the frame side engaging portion and the main body side engaging portion The belt unit rotates around the contact portion of the belt and the other end floats. At this time, the support shaft portion (or contact portion) abuts and is pressed against the pressing portion of the apparatus main body, thereby suppressing rotation around the contact portion between the frame side engaging portion and the main body side engaging portion. In this case, the belt unit rotates around the contact portion between the support shaft portion (or contact portion) and the pressing portion. That is, the contact portion between the support shaft portion (or contact portion) and the pressing portion serves as a fulcrum, and the contact portion between the frame side engagement portion and the main body side engagement portion serves as an action point. The engaging part is strongly pressed toward the main body side engaging part. Thereby, the convex frame side engaging portion surely enters and fits into the concave main body side engaging portion, and positioning of the belt unit is ensured.

  According to the present invention, the support shaft portion (or the contact portion) can be pressed by the pressing portion, so that the front end of the belt unit can be reliably suppressed and positioning can be performed reliably.

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In the drawings to be referred to, FIG. 1 is a cross-sectional view showing an overall configuration of a color printer as an example of an image forming apparatus. In the following description, first, the overall configuration of the color printer will be briefly described, and then the details of the characteristic portions of the present invention will be described.

  In the following description, the direction will be described with reference to the user when using the color printer. That is, in FIG. 1, the left side toward the paper surface is “front side (front side)”, the right side toward the paper surface is “rear side (back side)”, the back side toward the paper surface is “left side”, and it faces the paper surface. Let the near side be the “right side”. In addition, the vertical direction toward the page is defined as the “vertical direction”.

  As shown in FIG. 1, the color printer 1 includes, in the apparatus main body 10, a paper feeding unit 20 that supplies paper P as an example of a recording sheet, and an image forming unit 30 that forms an image on the fed paper P. And a paper discharge unit 90 for discharging the paper P on which the image is formed.

  The upper wall of the apparatus body 10 is an upper cover that can be opened and closed vertically. An upper surface of the upper cover serves as a paper discharge tray 13 for accumulating the paper P discharged from the apparatus main body 10, and a plurality of LED attachment members 14 for holding LED units 40 described later are provided on the lower surface. ing.

  The paper feeding unit 20 is provided in the lower part of the apparatus main body 10, and a paper feeding tray 21 that is detachably attached to the apparatus main body 10, and a paper supply mechanism that conveys the paper P from the paper feeding tray 21 to the image forming unit 30. 22 is mainly provided. In the paper supply unit 20, the paper P in the paper supply tray 21 is separated one by one by the paper supply mechanism 22 and supplied to the image forming unit 30.

  The image forming unit 30 mainly includes four LED units 40, four process cartridges 50, a conveyance belt unit 70, and a fixing unit 80.

  The LED unit 40 includes a plurality of LEDs so as to expose a photosensitive drum 53 described later.

  The process cartridge 50 is arranged side by side in the front-rear direction, and includes a photosensitive drum 53 on which an electrostatic latent image is formed, a known charger, a developing roller, a toner storage chamber, and the like that are omitted from the reference numerals. Yes.

  The conveyance belt unit 70 is provided between the paper feeding unit 20 and each process cartridge 50, and mainly includes a driving roller 71, a driven roller 72, a conveyance belt 73, and a transfer roller 74. The detailed structure around the conveyor belt unit 70 will be described in detail later.

  The driving roller 71 and the driven roller 72 are arranged in parallel in a spaced manner in the front-rear direction, and a conveyance belt 73 formed of an endless belt is stretched between them. The conveyor belt 73 is disposed so as to face each photosensitive drum 53. In addition, four transfer rollers 74 that sandwich the conveyor belt 73 between the photosensitive drums 53 are arranged inside the conveyor belt 73 so as to face the photosensitive drums 53. A transfer bias is applied to the transfer roller 74 by constant current control during transfer.

  The fixing unit 80 includes a heating roller 81 and a pressure roller 82 that presses the heating roller 81.

  In the image forming unit 30 configured as described above, first, the surface of each photosensitive drum 53 is uniformly charged by a charger and then exposed by each LED unit 40. As a result, the potential of the exposed portion is lowered, and an electrostatic latent image based on the image data is formed on each photosensitive drum 53. Thereafter, toner is supplied to the electrostatic latent image from the developing roller, so that the toner image is carried on the photosensitive drum 53.

  Next, when the paper P is transported between the photosensitive drums 53 and the transport belt 73, a transfer bias is applied to the transfer rollers 74, whereby the toner images formed on the photosensitive drums 53 are transferred to the paper. Transferred onto P. Thereafter, as the paper P passes between the heating roller 81 and the pressure roller 82, the toner image transferred onto the paper P is thermally fixed.

  The paper discharge unit 90 mainly includes a plurality of pairs of transport rollers 92 that transport the paper P. The sheet P on which the toner image has been transferred and heat-fixed is discharged to the outside of the apparatus main body 10 by the transport roller 92 and accumulated in the discharge tray 13.

<Detailed structure around the conveyor belt unit>
Next, a detailed structure around the conveyor belt unit will be described. In the drawings to be referred to, FIG. 2 is a perspective view showing a conveyor belt unit, FIG. 3 is a sectional view (a) showing a structure around a bearing at the front portion of the conveyor belt unit, a side view (b) of the bearing, It is a side view (c) which shows the state which attached the bearing to the flame | frame. 4 is a perspective view (a) showing the left side panel, an explanatory view (b) showing the relationship between the long hole and the positioning projection, and FIG. 5 is a perspective view showing the right side panel.

<Detailed structure of conveyor belt unit>
As shown in FIG. 2, the conveyance belt unit 70 includes various parts such as the driving roller 71 described above, and also includes a resin frame 75 that rotatably supports the rollers such as the driving roller 71. The frame 75 extends in the front-rear direction and is disposed on the left and right sides of the drive roller 71 and the like, and the front end portions of the pair of side beams 75A, 75B (one end portion in the extending direction of the conveyor belt 73). ) And a handle 75D formed so as to extend upward from the front beam 75C.

  At the rear ends of the side beams 75A and 75B (the other end in the direction in which the conveyor belt 73 is stretched) when the conveyor belt unit 70 is attached to the apparatus main body 10, the apparatus main body 10 (details will be described later). 111), a support shaft portion 75E that is rotatably supported is formed. Specifically, the support shaft portion 75 </ b> E is formed coaxially with a drive gear 71 </ b> A that receives the drive from the drive roller 71 and the apparatus main body 10 and drives the drive roller 71.

  Further, a convex as an example of a frame side engaging portion for positioning the transport belt unit 70 in the left-right direction with respect to the apparatus body 10 between the support shaft portion 75E and the handle 75D in the left side beam 75A. Two positioning protrusions 75F are formed on the front and rear sides. The positioning protrusion 75F is formed only on the left side beam 75A, and is formed so as to protrude downward from the lower surface of the left side beam 75A. And the positioning protrusion 75F is formed in the shape of a cross rib, and the front-end | tip part has a tapered shape.

  Note that positioning of the conveyor belt unit 70 in the front-rear direction can be appropriately performed by a known structure and method. For this reason, in the present embodiment, description of positioning in the front-rear direction is omitted.

  In addition, a contact portion 75G formed so as to protrude rearward from the drive roller 71 is provided behind the support shaft portion 75E in each of the side beams 75A and 75B. Specifically, the contact portion 75G is formed such that the upper surface thereof is formed substantially parallel to the conveyance surface of the conveyance belt 73 and the lower surface thereof is gradually inclined upward as it goes rearward. The tip is tapered.

  Further, as shown in FIGS. 3A to 3C, a bearing B for rotatably supporting the driven roller 72 is provided at the front portion of each side beam 75A, 75B. Here, as shown in FIG. 3A, the driven roller 72 is a roller that regulates meandering of the conveyor belt 73, and the inner side of the belt guide 73 </ b> A provided on the left and right sides of the inner peripheral surface of the conveyor belt 73. There is a restricting surface 72A that can contact the surface.

  Conventionally, such a driven roller 72 has been movable in the axial direction with a somewhat large stroke, so that the conveyor belt 73 that moves following the movement of the driven roller 72 does not hit each side beam 75A, 75B. There is a problem that the apparatus becomes large by increasing the distance between the side beams 75A and 75B. On the other hand, in this embodiment, the movement of the driven roller 72 in the axial direction is restricted by the bearing B, so that the size of the apparatus is reduced.

  Specifically, a groove 72C communicating in the circumferential direction is formed at a position away from the tip of the rotation shaft 72B of the driven roller 72, and a thickness slightly smaller than the width of the groove 72C is formed in the groove 72C. The bearing B is arranged. As a result, only a slight gap is formed between the left and right end surfaces of the bearing B and the left and right inner surfaces of the groove 72C, so that the movement of the driven roller 72 can be kept small.

  3B and 3C, the bearing B has a hole having a diameter larger than the rotation shaft 72B of the driven roller 72 and a portion where the groove 72C is formed in the rotation shaft 72B ( A hole portion B1 having a shape in which a portion having a small diameter) and a hole having substantially the same diameter are connected to each other is formed. Accordingly, when the bearing B is mounted on the driven roller 72, the bearing B can be mounted by passing the rotating shaft 72B of the driven roller 72 through the large diameter portion of the hole B1 of the bearing B.

  Further, after passing the rotating shaft 72B of the driven roller 72 through the large-diameter portion of the hole B1 of the bearing B, the spring S is attached between the rear portion of the bearing B and the side beam 75A. Is pushed forward. As a result, the small-diameter portion of the rotation shaft 72B (the portion of the groove 72C) is rotatably supported by the small-diameter portion of the hole B1 of the bearing B, and the driven roller 72 is pushed forward via the bearing B to convey the conveyor belt. 73 is stretched.

<Detailed structure of device body>
As shown in FIGS. 4A and 5, a resin left side panel 110 and a right side panel 120 to which the transport belt unit 70 and the like are attached are provided on both the left and right sides in the apparatus main body 10.

  As shown in FIG. 4A, the left side panel 110 is fitted with a support surface 111 that rotatably supports the support shaft portion 75E of the conveyor belt unit 70, and the positioning protrusions 75F of the conveyor belt unit 70. The main body side engaging portion is mainly formed with two concave long holes 112 and a pressing portion 113 located obliquely above the support surface 111.

  The support surface 111 is formed in a horizontal flat shape, and is in a position to support the support shaft portion 75 </ b> E of the transport belt unit 70 when the transport belt unit 70 is mounted at a normal position with respect to the apparatus main body 10. Is formed. The support surface 111 is in contact with the support shaft portion 75E and supports the support shaft portion 75E so that the support shaft portion 75E can turn in the middle of mounting the obliquely inclined conveying belt unit 70 to the apparatus main body 10. It has become.

  As shown in FIG. 4B, the long hole 112 is a long hole that is long in the front-rear direction, and its left-right width L1 is larger than the maximum width L2 (left-right width of the root portion) of the positioning protrusion 75F of the conveyor belt unit 70. It is formed slightly smaller. Here, both the left side panel 110 in which the long hole 112 is formed and the positioning protrusion 75F of the conveyor belt unit 70 are made of resin. As a result, the long hole 112 and the positioning protrusion 75F are closely fitted, and the conveyance belt unit 70 is positioned in the left-right direction. Then, as shown in FIG. 4A, each long hole 112 is formed at a predetermined position with respect to the support surface 111. Specifically, each elongated hole 112 has an arc-shaped locus centering on the support shaft portion 75E when the transport belt unit 70 is rotated about the support shaft portion 75E supported by the support surface 111. It is formed at a position that can be fitted with each of the moving positioning protrusions 75F.

  When the positioning protrusion 75F and the long hole 112 are fitted by the rotation of the conveyance belt unit 70, the pressing portion 113 contacts the contact portion 75G of the conveyance belt unit 70 and suppresses the lifting of the support shaft portion 75E. More specifically, the pressing portion 113 has a pressing surface 114 that intersects the moving direction of the abutting portion 75G that moves along an arcuate locus centering on the support shaft portion 75E.

  Further, on the lower side of the pressing portion 113, a regulating portion having a shape along a substantially vertical direction (specifically, a moving direction of the abutting portion 75G that moves along an arc-shaped locus centering on the support shaft portion 75E). 115 is formed. The restricting portion 115 can come into contact with the tip of the abutting portion 75G of the conveyor belt unit 70, thereby restricting rearward movement of the conveyor belt unit 70.

  Further, a guide portion 116 that guides the contact portion 75G of the transport belt unit 70 toward the lower side of the pressing surface 114 (a position facing the pressing surface 114) is provided above the pressing portion 113. The guide portion 116 is an inclined surface that is inclined backward as the front surface thereof goes downward (see FIG. 6).

  Also, on the front side of the support surface 111 described above, a first guide surface 117 that is horizontally formed at a position that is one step lower than the support surface 111, and an inclination that rises upward from the front end of the first guide surface 117 toward the front. A second guide surface 118 and the like are formed. Thereby, even if the support shaft portion 75E of the conveyor belt unit 70 is slid on the second guide surface 118 and the first guide surface 117, the contact portion 75G of the conveyor belt unit 70 is guided to the lower side of the pressing surface 114. can do.

  Further, by forming the support surface 111 with a smaller area than the first guide surface 117 by projecting from the first guide surface 117, only a small portion corresponding to the small support surface 111 can be accurately formed in the manufacture of the mold. Therefore, the manufacturing of the mold can be simplified as compared with the case where everything is formed with high accuracy. Moreover, since the location where the accuracy is measured is clearly defined by projecting the location requiring accuracy, the measurement can be easily performed. If the support surface 111 is formed to be smaller than the first guide surface 117, the above-described effects can be obtained.

  As shown in FIG. 5, the right side panel 120 has the same support surface 121 as the left side panel 110. Thus, the support shaft portion 75E of the conveyor belt unit 70 is rotatably supported by the support surfaces 111 and 121 of the left side panel 110 and the right side panel 120. The right side panel 120 has a first guide surface 127 and a second guide surface 128 that are the same as the left side panel 110. Accordingly, even if the left and right support shaft portions 75E are slid on the left and right guide surfaces 118, 128, 117, and 127, the support shaft portions 75E can be positioned on the support surfaces 111 and 121, respectively. It has become.

  Further, the right side panel 120 is provided with a pressing portion 123 (pressing surface 124) that contacts the contact portion 75G of the transport belt unit 70 and suppresses the lifting of the support shaft portion 75E. Accordingly, the lifting of the left and right support shaft portions 75E of the transport belt unit 70 is suppressed in a well-balanced manner by the left and right pressing portions 113 and 123 (the pressing surfaces 114 and 124).

  Further, the right side panel 120 is formed with a regulating portion 125 that regulates the backward movement of the conveyor belt unit 70 by contacting the support shaft portion 75E of the conveyor belt unit 70. Accordingly, the conveyance belt unit 70 is supported in a balanced manner by the left and right regulating portions 115 and 125, so that the movement of the conveyance belt unit 70 to the rear is reliably prevented.

  Further, the right side panel 120 is formed with a guide portion 126 that guides the contact portion 75G of the transport belt unit 70 below the pressing surface 124. Accordingly, the abutting portions 75G of the conveyor belt unit 70 are supported by the left and right guide portions 116 and 126 in a well-balanced manner, and are well guided below the pressing surfaces 114 and 124. The right side panel 120 is not formed with the long hole 112 provided in the left side panel 110 as described above.

<Mounting method of conveyor belt unit>
Next, a method for attaching the conveyor belt unit 70 will be described. In the drawings to be referred to, FIG. 6 is a cross-sectional view showing the operation of inserting the contact portion below the pressing surface. FIG. 7 is an enlarged cross-sectional view showing a state in which the positioning protrusion is caught in the long hole, FIG. 8 is an enlarged cross-sectional view showing a state in which the contact portion is in contact with the pressing surface, and FIG. It is an expanded sectional view which shows the state with which the conveyance belt unit was mounted | worn.

  As shown in FIG. 6, when the user first holds the handle 75D, the posture of the conveyor belt unit 70 is in an inclined state in which the support shaft portion 75E is positioned below the handle 75D due to the weight of the rear portion. Then, with this posture, the contact portion 75G of the transport belt unit 70 is brought into contact with the guide portion 116, and the contact portion 75G is slid along the front surface of the guide portion 116. Thereby, the contact part 75G is guided to the lower side of the pressing surface 114. At this time, the contact portion 75G that has entered under the pressing surface 114 comes into contact with the restriction portion 115, so that the transport belt unit 70 does not move too far backward, and the support shaft portion 75E is surely attached to the support surface 111. It stops at the position and is supported by the support surface 111.

  Thereafter, by lowering the handle 75D, the conveyor belt unit 70 is rotated around the support shaft portion 75E, and the positioning protrusions 75F of the conveyor belt unit 70 are fitted into the elongated holes 112 of the left side panel 110. Combine. At this time, as shown in FIG. 7, when both the left and right sides of the positioning projection 75F are caught in the narrow long hole 112, as shown in FIG. 8, the conveyor belt unit 70 is rotated around the caught portion.

  As a result, the support shaft portion 75E of the conveyor belt unit 70 floats from the support surface 111. However, when the contact portion 75G of the conveyor belt unit 70 contacts and is pressed against the pressing surface 114, a further conveyor belt is obtained. The rotation of the unit 70 is suppressed. Thereafter, when the handle 75D is further pushed down, the transport belt unit 70 rotates around the contact portion between the contact portion 75G and the pressing surface 114. That is, the contact portion between the contact portion 75G and the pressing surface 114 serves as a fulcrum, and the contact portion between the positioning projection 75F and the long hole 112 serves as an action point. Pressed strongly. As a result, as shown in FIG. 9, the positioning protrusion 75 </ b> F reliably enters and fits into the long hole 112, and the left and right positioning of the transport belt unit 70 is reliably performed. At this time, the driving gear 71 </ b> A (FIG. 2) is connected to a main body side driving gear (not shown), so that the driving force on the apparatus main body 10 side can be appropriately transmitted to the transport belt unit 70.

According to the above, the following effects can be obtained in the present embodiment.
Since the abutting portion 75G can be pressed by the pressing surface 114 (the pressing portion 113), it is possible to reliably prevent the leading end of the conveyor belt unit 70 from being lifted and to perform positioning.

  Since the restricting portion 115 that restricts the rearward movement of the transport belt unit 70 is formed, the support shaft portion 75E can be reliably placed on the support surface 111.

  Since the guide portion 116 for guiding the contact portion 75G to the position below the pressing surface 114 is provided, the contact portion 75G can be reliably disposed below the pressing surface 114, and the effect of the pressing surface 114 can be ensured. Obtainable.

  Since the positioning projection 75F and the long hole 112 are fitted together, the conveying belt unit 70 can be reliably fixed to the apparatus main body 10. Note that the present invention is particularly effective for a form in which the interference fit is performed as in the present embodiment, and the above-described “leverage principle” can be effectively used to perform the interference fit with a small force.

In addition, this invention is not limited to the said embodiment, It can utilize with various forms so that it may illustrate below.
In the above-described embodiment, the frame-side engaging portion is the convex positioning projection 75F and the main body-side engaging portion is the concave long hole 112. However, the present invention is not limited to this, and the concavo-convex relationship is reversed. Also good. Moreover, although the long hole 112 which penetrated was utilized in the said embodiment, this invention is not limited to this, You may employ | adopt the bottomed cylindrical recessed part which is not penetrated.

  In the above embodiment, the support shaft portion 75E is formed coaxially with the drive roller 71. However, the present invention is not limited to this, and may not be coaxial.

  In the above-described embodiment, the pressing portion 113 is formed at a position where the conveyance belt unit 70 contacts the contact portion 75G. However, the present invention is not limited to this, and the position contacting the support shaft portion, that is, the support shaft portion (support A pressing portion may be formed above the surface. However, in this case, since it is necessary to insert the support shaft portion into a narrow space between the support surface and the pressing portion, and the belt unit mounting work may be complicated, the support shaft portion 75E as in the above embodiment. It is desirable to employ a structure in which the abutting portion 75G located rearward (frontward in the mounting direction) abuts against the pressing portion 113.

  In the embodiment, the positioning protrusion 75F and the portion (the left side panel 110) where the long hole 112 is formed are both formed of resin, but the present invention is not limited to this, and at least one of these is formed of resin. It only has to be.

  In the above-described embodiment, the contact portion 75G and the restriction portion 115 are brought into contact with each other in order to restrict movement of the transport belt unit 70 to the rear side (the other end side), but the present invention is not limited thereto. The restricting portion may be brought into contact with any part of the belt unit.

In the said embodiment, although the support surface was made into the flat surface, this invention is not limited to this, It is good also as a curved surface which follows the outer peripheral part of a support shaft part.
In the above-described embodiment, the transport belt unit 70 that transports the paper P is used as the belt unit. However, the present invention is not limited to this, and may be a belt unit having an intermediate transfer belt.

In the above embodiment, the present invention is applied to the color printer 1. However, the present invention is not limited to this, and the present invention may be applied to other image forming apparatuses such as a copying machine and a multifunction machine.
In the above-described embodiment, paper P such as thick paper, postcard, and thin paper is used as an example of the recording sheet. However, the present invention is not limited to this, and may be, for example, an OHP sheet.

1 is a cross-sectional view illustrating an overall configuration of a color printer as an example of an image forming apparatus. It is a perspective view which shows a conveyance belt unit. They are sectional drawing (a) which shows the structure around the bearing of the front part of a conveyance belt unit, the side view (b) of a bearing, and the side view (c) which shows the state which attached the bearing to the flame | frame. It is the perspective view (a) which shows a left side panel, and explanatory drawing (b) which shows the relationship between a long hole and a positioning protrusion. It is a perspective view which shows a right side panel. It is sectional drawing which shows the operation | work which inserts a contact part under the pressing surface. It is an expanded sectional view showing the state where the positioning projection was caught in the long hole. It is an expanded sectional view which shows the state which the contact part contact | abutted to the pressing surface. FIG. 6 is an enlarged cross-sectional view illustrating a state where a conveyance belt unit is mounted at a regular position.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Color printer 10 Main body 70 Conveyor belt unit 71 Drive roller 72 Driven roller 73 Conveyor belt 75 Frame 75A Side beam 75C Front beam 75D Handle 75E Support shaft part 75F Positioning protrusion 75G Contact part 110 Left side panel 111 Support surface 112 Long hole 113 Holding part 114 Holding surface 115 Restricting part 116 Guide part 120 Right side panel 121 Support surface

Claims (7)

A belt unit having a belt stretched between a pair of rollers and a frame that rotatably supports the pair of rollers;
An image forming apparatus comprising: an apparatus main body to which the belt unit is attached;
The belt unit is
A handle provided on one end side of the frame in the tensioning direction of the belt;
A support shaft provided on the other end side in the extending direction of the frame, and supported rotatably by the apparatus main body when the belt unit is mounted;
A frame side engagement portion provided between the support shaft portion and the handle and formed in a convex shape or a concave shape for positioning of the belt unit;
The apparatus main body is
A support surface that rotatably supports the support shaft portion;
A main body side engaging portion whose concave-convex shape is opposite to that of the frame side engaging portion in order to be fitted to the frame side engaging portion that moves along an arcuate locus centering on the support shaft portion; ,
When the frame side engaging portion and the main body side engaging portion are fitted together, a presser that abuts against the support shaft portion or the contact portion on the other end side of the support shaft portion to suppress the lifting of the support shaft portion. And an image forming apparatus. The apparatus main body is
The image forming apparatus according to claim 1, further comprising a restricting portion that contacts the belt unit in order to restrict movement of the belt unit toward the other end. The apparatus main body is
The image forming apparatus according to claim 1, further comprising a guide portion that guides the contact portion at a position facing the pressing portion.   The said abutting part is formed so that it may protrude in the other end side rather than the roller provided in the other end side of the said frame, The any one of Claims 1-3 characterized by the above-mentioned. Image forming apparatus.   The image forming apparatus according to claim 4, wherein the pressing portion has a pressing surface that intersects a moving direction of the contact portion that moves along an arc-shaped locus centering on the support shaft portion. At least one of the frame side engaging portion and the main body side engaging portion is made of resin,
5. The image forming apparatus according to claim 1, wherein the frame side engaging portion and the main body side engaging portion are fitted to each other. A photosensitive drum disposed opposite to the belt unit;
The image forming apparatus according to claim 1, wherein the belt unit is a conveyance belt unit that conveys a recording sheet to and from the photosensitive drum.

Images