JP4569645B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and is particularly effective when applied to an electrophotographic image forming apparatus.

  For example, in the image forming apparatus described in Patent Document 1, a belt unit (transfer unit) having a belt spanned between two rollers can be attached to and detached from the apparatus main body frame, and the belt unit is attached and detached. In this case, the belt unit (transfer unit) is provided with a gripping portion that is gripped by a user or a service person.

And in invention of patent document 1, it has the structure which fixes a belt unit to an apparatus main body frame with the front-end | tip part of the holding part extended upwards, and the supported part which protruded and provided in the side surface of the belt unit. .
JP 2007-101728 A

  An object of the present invention is to detachably attach a belt unit to an apparatus main body frame with a novel configuration different from the invention described in Patent Document 1.

In order to achieve the above object, the present invention provides an image forming apparatus for forming an image on a recording sheet according to the first aspect of the present invention, comprising an apparatus main body frame (1B) and an apparatus main body frame (1B). The first roller (12B), the second roller (12A), the first roller (12B), and the first roller (12B), which are detachably mounted and are respectively disposed near both ends of the belt unit main frame (11) and the belt unit main frame (11). In the belt (12C, 21) stretched between the second rollers (12A) and the belt unit main frame (11), provided on the axial end portions of the first roller (12B) and the second roller (12A). is a belt a belt unit having both belt unit side frames extending in stretched direction parallel to the direction of the (12C, 21) (13) (10,20) Provided in the first roller (12B) side of the belt unit (10, 20), the side gripping frame provided in the longitudinal end of both the belt unit side frames (13) (15A), and two side gripping frame (15A And a gripping portion (15) having a bridge portion (15B) extending in the width direction parallel to the axial direction of the first roller (12B) so as to bridge between the gripping portion (15), And a holding mechanism (16) for holding the position of the belt unit (10, 20) with respect to the frame (1B).

In the first aspect of the present invention, the holding mechanism (16) is provided with the first contacted portion (16B) that comes into contact with the first contact portion (1G) provided on the apparatus main body frame (1B). The lever member (16A) and the elastic means (16C) for causing the lever member (16A) to act on the lever member (16A) with an elastic force in a direction to increase the contact surface pressure between the first contact portion (1G) and the first contacted portion (16B). It is characterized by having.

In the first aspect of the present invention, the elastic means (16C) is a coiled spring, and the elastic means (16C) has an axial direction from the first roller (12B) side to the grip portion (15). ) Are arranged so as to be parallel to the direction toward the tip side.

  The phrase “the axial direction of the elastic means is parallel to the direction from the first roller (12B) side toward the front end side of the grip portion (15)” is limited to “parallel” in a strict sense. Rather, it also includes the range of parallelism that seems to be almost parallel by visual inspection.

In the invention according to claim 1 , the lever member (16A) is provided with the first arm portion (16D) on which the elastic force of the elastic means (16C) acts and the first contacted portion (16B). It has a second arm portion (16E) and is bent in a generally U shape, and is rotatably attached to the grip portion (15) at the bent portion (16F). 10 and 20) are attached to the apparatus body frame, the longitudinal direction of the first arm portion (16D) and the axial direction of the elastic means (16C) are orthogonal to each other, and the longitudinal direction of the second arm portion (16E). The direction and the stretching direction of the belt (12C, 21) are orthogonal to each other.

Note that the term “orthogonal” is not limited to “orthogonal” in a strict sense, but also includes an orthogonality in a range that is considered to be approximately parallel by visual observation.
Further, in the first aspect of the present invention, when the direction parallel to the axial direction of the first roller (12B) is referred to as the width direction, the side gripping frame (15A) is a stretch of the belt (12C, 21). The plate unit has a plate-like frame wall (15E) that is orthogonal to a virtual plane parallel to the portion and parallel to the longitudinal direction of the belt unit side frame (13). ) Provided with the frame wall (15E), the dimension (W) of the portion parallel to the stretching direction increases from the front end side of the grip portion (15) toward the first roller (12B) side, and The shape seen from the width direction is a triangular shape so that a portion of the edge portion from the first roller (12B) side toward the front end side of the grip portion (15) is inclined.
The invention according to claim 2 is characterized in that the side surface portion is a portion on one end side in the width direction of the grip portion.
The invention according to claim 3 is characterized in that the holding mechanism (16) is provided on the side of the belt unit side frame (13) in the grip portion (15).

With the configuration described above, in the present invention, the belt unit can be detachably assembled to the apparatus main body frame with a new configuration different from the invention described in Patent Document 1.
In the specification of the present application, the following image forming apparatus is also included.

  That is, an image forming apparatus for forming an image on a recording sheet, which is detachably attached to the apparatus main body frame (1B) and the apparatus main body frame (1B), and includes a belt unit main frame (11), a belt unit main frame ( 11) a first roller (12B) and a second roller (12A) disposed near both ends of the belt, a belt (12C, 21) stretched between the first roller (12B) and the second roller (12A), In addition, in the belt unit main frame (11), a belt provided on the axial direction end side of the first roller (12B) and the second roller (12A) and extending in a direction parallel to the stretching direction of the belt (12C, 21). A belt unit (10, 20) having a unit side frame (13), and a first roller (12B) of the belt units (10, 20). Gripping portion (15) provided on the side, and the first contact portion (1G) provided on the belt unit side frame (13B) side of the gripping portion (15) and provided on the apparatus body frame (1B). The first contacted portion (16B) and the belt unit (10, 20) are provided on the second roller (12A) side and contact the second contact portion (1H) provided on the apparatus main body frame (1B). An image forming apparatus comprising: a second contacted portion (11A).

  Further, when a virtual plane including an end portion on the side opposite to the first roller (12B) among the side side ends of the belt unit side frame (13) is defined as an anti-roller side virtual plane (S2), The image forming apparatus, wherein the contact portion (16B) is located closer to the first roller (12B) than the opposite roller-side virtual plane (S2).

  Further, when a virtual plane including an end portion on the first roller (12B) side among the side side end portions of the belt unit side frame (13) is a roller-side virtual plane (S1), a first contacted portion ( 16B) is an image forming apparatus that is located on the side opposite to the roller side virtual plane (S2) from the roller side virtual plane (S1).

  The first contacted portion (16B) is provided in a region (V1) occupied by the extended virtual belt unit side frame when the belt unit side frame (13) is extended toward the gripping portion (15). An image forming apparatus.

The second contact portion (1H) is provided in a portion of the apparatus main body frame (1B) facing the belt unit side frame (13).
Thereby, the first contacted part (16B) and the second contacted part (11A) are both located in the region occupied by the belt unit side frame (13) or the virtual belt unit side frame.

  Further, the side surface portion (15E) provided with the first contacted portion (16B) in the grip portion (15) has a wall-like rib (15F, 15G) protruding in the axial direction from the side surface portion (15E). An image forming apparatus comprising:

  The first roller (12B) can be displaced in the longitudinal direction of the belt unit side frame (13), and the second roller (12A) rotates without being displaced with respect to the belt unit side frame (13). Thus, a driving force is applied to the belt (12C, 21), and further, a force in a direction to increase the contact surface pressure between the second contact portion (1H) and the second contacted portion (11A) is applied to the belt unit (10). , 20), and the second contacted portion (11A) has a second roller (12A) from the midpoint position between the first roller (12B) and the second roller (12A). An image forming apparatus arranged on the side.

  The first contact portion (1G), the first contacted portion (16B), the second contact portion (1H), and the second contacted portion (11A) are provided on one end side in the axial direction, and the device in the axial direction An image forming apparatus comprising a width direction positioning portion (1L, 1M) for determining a position of the belt unit (10, 20) with respect to the main body frame (1B) on one end side in the axial direction.

  Further, the belt unit main frame (11) and the belt unit side frame (13) are separate bodies, and the second contacted part (11A) is provided on the belt unit main frame (11). Forming equipment.

  Incidentally, the reference numerals in parentheses for each of the above means are examples showing the correspondence with the specific means described in the embodiments described later, and the present invention is indicated by the reference numerals in the parentheses of the above respective means. It is not limited to specific means.

In this embodiment, the image forming apparatus according to the present invention is applied to an electrophotographic image forming apparatus, and the embodiment of the present invention will be described below with reference to the drawings.
1. DESCRIPTION OF THE DRAWINGS FIG. 1 is a central sectional view showing a main part of an image forming apparatus 1 according to the present embodiment, and FIG. 2 is a central sectional view showing a state in which a top cover 1F of the image forming apparatus 1 is opened. 3 is a view of the state in which the belt unit 10 is assembled to the apparatus main body frame 1B (image forming apparatus 1) as seen from the upper surface side, and FIG. 4 is a view showing the positional relationship between the process cartridge 3K and the belt unit 10. FIG. 5 is a perspective view of the belt unit 10.

  6 is a perspective view showing a state in which the belt unit 10 is attached and detached, FIG. 7 is a view showing a state in which the belt unit 10 is detached from the apparatus main body frame 1B (image forming apparatus 1), and FIG. FIG. 9 is a left side view of FIG. 8, and FIG. 10 is a belt unit side frame 13 at one end in the width direction from the belt unit 10 (the left belt unit side frame 13). ) Is removed, and FIGS. 11A to 11C are views showing the operation of the chute 15D provided in the belt unit 10. FIG.

2. Schematic Configuration of Image Forming Apparatus An image forming unit 2 that forms an image on a sheet or an OHP sheet (hereinafter referred to as sheet) includes four process cartridges 3K, 3Y, 3M, 3C, and an exposure unit 4 as shown in FIG. And a fixing device 5 and the like.

  In the present embodiment, the image forming unit 2 includes four types of four process cartridges 3K, 3Y, 3M, and 3C that correspond to four color developers (toners) of black, yellow, magenta, and cyan. A direct tandem system is used in which a developer image is superimposed on a sheet to form a color image on the sheet.

  That is, among the plurality of sheets placed on the sheet feeding tray 6, the sheet located at the top of the stacking direction picked up by the sheet feeding mechanism (feeder unit) 7 is separated by the paper dust removing roller 8. Is removed, and is conveyed to a pair of registration rollers 9. After the skew is corrected by the pair of registration rollers 9, it is conveyed to the belt unit 10. Details of the belt unit 10 will be described later.

  The four process cartridges 3K and the like are arranged in series in the order of the process cartridges 3K, 3Y, 3M, and 3C from the upstream along the sheet conveyance direction on the sheet conveyance surface side of the belt unit 10.

  For this reason, four types of developer images are sequentially transferred onto the paper transported on the belt unit 10, and the developer images that have been transferred onto the paper are heated by the fixing device 5 to be paper. To settle.

Then, the sheet on which image formation has been completed discharged from the fixing device 5 is turned upward, and then discharged to a paper discharge tray 1A provided on the upper end surface side of the image forming apparatus 1.
Each process cartridge 3K, 3Y, 3M, 3C contains a photosensitive drum 3A on which a developer image is carried, a charger (not shown) for charging the photosensitive drum 3A, and the like. Then, after exposing the charged photosensitive drum 3A with the exposure device 4 to form an electrostatic latent image on the outer peripheral surface of the photosensitive drum 3A, if a developer is supplied to the photosensitive drum 3A, the developing is performed on the outer peripheral surface of the photosensitive drum 3A. An agent image is carried (formed).

  The fixing unit 5 is also provided with a heating roller 5A for heating the developer to fix the developer image on the sheet, and a heating roller 5A disposed on the opposite side of the heating roller 5A across the conveyed sheet. It is composed of a pressure roller 5B pressed against the side.

  By the way, as shown in FIG. 7, the apparatus main body frame 1B that forms a part of the apparatus main body of the image forming apparatus 1 is covered with a casing 1C that constitutes an exterior design surface, and includes four process cartridges 3K, 3Y, The 3M, 3C, and belt unit 10 are detachably attached to the apparatus main body frame 1B.

  The apparatus main body frame 1B is a plate-shaped apparatus main body side frame 1D provided on both ends in the width direction (left and right direction) of the image forming apparatus 1, and an apparatus main body connection frame for connecting these apparatus main body side frames 1D (see FIG. Etc.).

  Incidentally, in FIG. 7, only the apparatus main body side frame 1D on the one end side (left side) in the width direction is shown, and the apparatus main body side frame 1D and the apparatus main body connection frame on the other end side in the width direction are omitted.

  Each of the two apparatus main body side frames 1D holds four process cartridges 3K, 3Y, 3M, and 3C, and when these process cartridges 3K are mounted on the apparatus main body frame 1B (image forming apparatus 1). In addition, four mounting grooves 1E for guiding the process cartridge 3K and the like in a predetermined direction are provided, and these mounting grooves 1E extend from the upper side to the lower side so as to be inclined with respect to the vertical direction. .

  Further, the top cover 1F provided with the paper discharge tray 1A in the housing 1C is assembled to the housing 1C so as to be swingable (openable / closable), and the top cover 1F is disposed on the upper side as shown in FIG. The upper side of the four process cartridges 3K, 3Y, 3M, and 3C (image forming apparatus 1) can be opened.

  Therefore, when the process cartridge 3K or the like is attached to or detached from the apparatus main body frame 1B (image forming apparatus 1), the top cover 1F is swung upward and the upper side of the image forming apparatus 1 is opened. The process cartridge 3K and the like may be inserted and removed in a direction from the upper front side toward the lower rear side.

  In order to remove the belt unit 10 from the apparatus main body frame 1B (image forming apparatus 1), first, the upper side of the image forming apparatus 1 is opened and the four process cartridges 3K, 3Y, 3M, and 3C are attached to the apparatus main body frame 1B. After removing from, as shown in FIG.

3. Configuration of belt unit 3.1. Basic Configuration of Belt Unit As described above, the belt unit 10 according to the present embodiment is disposed at a position facing the photosensitive drums 3A of the four process cartridges 3K, 3Y, 3M, and 3C, and conveys paper. It is.

  Specifically, as shown in FIG. 1, the belt unit 10 includes a driving roller 12A and a driven roller (tension roller) 12B having a rotating shaft parallel to the rotating shaft of the photosensitive drum 3A, and a driving roller 12A and a driven roller 12B. It is composed of a conveyor belt 12C or the like that is stretched between the sheets, and the sheet is conveyed while being placed on the conveyor belt 12C.

  The driving roller 12A receives a power supply from the apparatus main body (apparatus main body frame 1B) side to apply rotational driving to the conveying belt 12C, and the driven roller 12B is driven by the driving roller 12A along with the rotation of the conveying belt 12C. Rotate.

  The drive roller 12A is rotatably assembled to one end of the belt unit main frame 11 (see FIG. 10), while the driven roller 12B has an axial direction parallel to the drive roller 12A and the axial direction. The belt unit main frame 11 is assembled to the other end side so as to be rotatable and displaceable.

  Further, as shown in FIG. 10, a stretch of the conveyor belt 12C is stretched at portions corresponding to both ends of the belt unit main frame 11 in the axial direction of the drive roller 12A (hereinafter referred to as the width direction (left-right direction)). A belt unit side frame 13 is provided that extends in the direction, that is, the direction (front-rear direction) parallel to the direction from the driving roller 12A toward the driven roller 12B.

  For this reason, the driving roller 12A applies a driving force to the conveying belt 12C by rotating the position of the driving roller 12A with respect to the belt unit side frame 13 without being displaced in the stretching direction.

  On the other hand, the driven roller 12B receives an elastic force in a direction away from the driving roller 12A by a coil spring-like elastic member 12D provided on the belt unit side frame 13 as shown in FIG. On the other hand, by displacing in the longitudinal direction (stretching direction), a predetermined tension is applied to the transport belt 12C.

The belt unit side frame 13 is assembled and fixed to the belt unit main frame 11 so as to be detachable by mechanical fastening means such as screws 14.
Further, on the driven roller 12 </ b> B side of the belt unit 10, a grip portion 15 is provided for a user, a serviceman, or the like to grip the belt unit 10 when the belt unit 10 is attached or detached.

  As shown in FIGS. 5 and 10, the gripping portion 15 is arranged in the width direction so as to bridge between the side gripping frame 15 </ b> A provided at one end in the longitudinal direction of the belt unit side frames 13 and the side gripping frames 15 </ b> A. It is composed of a bridge portion 15B extending in the (left-right direction), a plate-like chute 15D that closes an opening portion 15C (see FIG. 11C) of the portal frame formed by the side gripping frame 15A and the bridge portion 15B. ing.

  As shown in FIGS. 11A to 11C, the chute 15D is assembled so that the bridge portion 15B side is swingably mounted on the side gripping frame 15A and is transported by the paper feed mechanism 7. It functions as a guide means for turning the sheet to the conveying belt 12C side.

  Further, as shown in FIG. 5, the side grip frame 15A is a plate-like frame wall 15E that is orthogonal to a virtual plane parallel to the stretched portion of the conveyor belt 12C and parallel to the longitudinal direction of the belt unit side frame 13. The first rib wall 15F and the second rib wall 15G protrude in a direction substantially orthogonal to the frame wall 15E (in the present embodiment, the width direction). Further, the lower side of the side gripping frame 15A, that is, the distal end side (the first contacted part 16B side) of the second arm part 16E described later is not provided with a wall part such as a rib wall and is open.

The stretched portion of the conveyance belt 12C is a planar portion on the conveyance belt 12C where paper is placed, and in the present embodiment, substantially coincides with the horizontal plane.
Further, the frame wall 15E is an end portion in the width direction (left-right direction) of the belt unit side frame 13, and includes a virtual plane including an end portion on the driven roller 12B side, that is, an end portion in the width direction of the conveying belt 12C. And it is located in the site | part substantially corresponding to 1st virtual plane S1 (refer FIG. 8) substantially orthogonal to a stretch part.

  On the other hand, the position of the front end of the first rib wall 15F in the protruding direction is an end in the width direction (left-right direction) of the belt unit side frame 13, and includes a virtual plane including an end opposite to the driven roller 12B. That is, it is parallel to the first virtual plane S1 and substantially coincides with the second virtual plane S2 (see FIG. 8) including the width direction end of the entire belt unit 10.

  Then, as shown in FIG. 9, the frame wall 15 </ b> E extends from the upper end side, which is the distal end side (bridge portion 15 </ b> B side) of the gripping portion 15, toward the driven roller 12 </ b> B side. It is formed in a triangular shape so that the dimension W of the parallel part is enlarged, and the inclination angle of the frame wall 15E on the process cartridge 3K side is substantially parallel to the inclination direction of the process cartridge 3K as shown in FIG. It is set to be.

  The first rib wall 15F is provided on the drive roller 12A side (process cartridge 3K side) of the edge of the frame wall 15E, while the second rib wall 15G is the first of the edges of the frame wall 15E. It is provided on the back side of the rib wall 15F (the front side of the image forming apparatus 1).

  The projecting dimension of the second rib wall 15G is set to be smaller than the projecting dimension of the first rib wall 15F (excluding the bridge portion 15B side). The protruding dimension of the first rib wall 15F or the second rib wall 15G refers to the dimension from the frame wall 15E to the tip of the portion protruding in the width direction (axial direction).

3.2. Configuration of Holding Mechanism and the like The holding mechanism 16 is a mechanism for holding the position of the belt unit 10 with respect to the apparatus main body frame 1B when the belt unit 10 is attached to the image forming apparatus 1. As shown in FIG. 9, the grip unit 15 is provided on the belt unit side frame 13 side, that is, on the frame wall 15E.

  That is, the holding mechanism 16 includes a lever member 16A provided with a first contacted part 16B that contacts the first contact part 1G provided on the apparatus main body frame 1B, and the first contact part 1G and the first contacted part 16B. The coil spring 16C or the like that causes the lever member 16A to act on the lever member 16A with an elastic force that increases the contact surface pressure.

As shown in FIG. 6, the first contact portion 1 </ b> G is configured by a protrusion protruding from the apparatus main body side frame 1 </ b> D toward the belt unit 10.
As shown in FIG. 9, the lever member 16 </ b> A is connected to one end in the axial direction of the spring 16 </ b> C, and has a first arm portion 16 </ b> D on which the elastic force of the spring 16 </ b> C acts, and a first contacted portion 16 </ b> B on the tip side. The second arm portion 16E is bent in a generally U shape and is rotatably assembled to the frame wall 15E by the bent portion 16F.

  Further, as shown in FIG. 8, the lever member 16A and the spring 16C, that is, the holding mechanism 16, are housed between the first virtual plane S1 and the second virtual plane S2, and the first contacted portion 16B is As shown in FIG. 9, when the belt unit side frame 13 is extended to the grip 15 side, it is provided in a region V1 occupied by the extended virtual belt unit side frame.

  That is, the first contacted portion 16B is on the side opposite to the driving roller 12A across the driven roller 12B, and the third virtual plane S3 and the lower end including the upper end of the end of the belt unit side frame 13 Is provided in a space surrounded by the fourth virtual plane S4 including the first virtual plane S1 and the second virtual plane S2.

In the present embodiment, the vertical direction coincides with the direction perpendicular to the longitudinal direction (stretching direction) and the width direction of the belt unit side frame 13.
When the belt unit 10 is mounted on the apparatus main body frame 1B, the longitudinal direction of the first arm portion 16D and the axial direction of the spring 16C are substantially orthogonal to each other, and the longitudinal direction of the second arm portion 16E is conveyed. The lever member 16A and the spring 16C are set so that the stretching direction of the belt 12C (the longitudinal direction of the belt unit side frame 13) is substantially orthogonal.

  Specifically, the first rib wall 15F continuously extending in a strip shape from the driven roller 12B side to the upper end side (bridge portion 15B) side of the grip portion 15 and the axial direction of the spring 16C are substantially parallel to each other. 16C is disposed, the longitudinal direction of the first arm portion 16D is substantially perpendicular to the extending direction of the first rib wall 15F, and the longitudinal direction of the second arm portion 16E is the front-rear direction of the image forming apparatus 1. It is comprised so that it may be substantially orthogonal to.

  Further, as shown in FIG. 6, the second portion of the apparatus main body frame 1 </ b> B (apparatus main body side frame 1 </ b> D) is a portion facing the belt unit side frame 13 and closer to the driving roller 12 </ b> A than the first contact portion 1 </ b> G. A contact portion 1H is provided.

  Incidentally, in FIG. 6, the casing 1C and the apparatus main body frame 1B (apparatus main body side frame 1D) are described as a single body. However, as described above, in the present embodiment, the apparatus main body frame 1B is the casing. The casing 1C and the apparatus main body frame 1B are separate from each other.

  On the other hand, the belt unit 10 is located on the one end side in the width direction of the belt unit 10 (belt unit side frame 13) and on the driving roller 12A side from the intermediate position between the driving roller 12A and the driven roller 12B. A second contacted portion 11A that comes into contact with the second contact portion 1H when mounted is provided.

  In the present embodiment, as shown in FIG. 10, the second contacted portion 11A is provided in the belt unit main frame 11 of the belt unit 10 and penetrates the belt unit side frame 13 in the width direction to It is provided so as to be exposed in the width direction of the unit 10.

  Then, as shown in FIG. 9, the first contacted portion 16B (lever member 16A) contacts the first contact portion 1G from the second rib wall 15G side and presses the first contact portion 1G toward the drive roller 12A side. In order to apply the pressing force F1, the belt unit 10 tries to move from the driving roller 12A side to the driven roller 12B side by the reaction force of the pressing force F1 that the lever member 16A applies to the first contact portion 1G.

  On the other hand, since the second contacted portion 11A contacts the second contact portion 1H from the drive roller 12A side, even if the reaction force acts on the belt unit 10, the belt unit from the drive roller 12A side to the driven roller 12B side. 10 is restricted from moving, the contact surface pressure between the second contact portion 1H and the second contacted portion 11A increases, and the position of the belt unit 10 in the front-rear direction (stretching direction) is determined and held. .

  Further, as shown in FIG. 6, the apparatus main body frame 1B is provided with reference surfaces 1J and 1K on which the belt unit 10 is placed. The reference surface 1J is in contact with the lower end side of the belt unit side frame 13 on the driven roller 12B side, and the reference surface 1K receives the axial end of the drive roller 12A.

  The first contact portion 1G and the second contact portion 1H are provided only on the device body side frame 1D on one end side in the axial direction (width direction), and the device body side on which the first contact portion 1G and the like are provided. The frame 1D is provided with width direction positioning portions 1L and 1M that determine the position of the belt unit 10 with respect to the apparatus main body frame 1B in the axial direction.

  The width direction positioning portions 1L and 1M are provided with locking holes into which the protruding portions 11B and 11C (see FIG. 10) provided in the belt unit 10 (belt unit main frame 11) are inserted. 11B is inserted and locked in the locking hole of the width direction positioning portion 1M, and the protrusion 11C is inserted and locked in the locking hole of the width direction positioning portion 1L.

  A transfer roller 3B (FIG. 1) transfers the developer image carried on the photosensitive drum 3A to the sheet on the apparatus body side frame 1D opposite to the apparatus body side frame 1D provided with the first contact portion 1G and the like. The electrode part 17 which supplies electric power is provided.

4). Features of the Image Forming Apparatus According to the Present Embodiment In this embodiment, the grip unit 15 is provided on the driven roller 12B side of the belt unit 10, and the first contacted part 16B is provided on the belt unit side frame 13 side of the grip unit 15. Since the second contacted portion 11A is provided on the drive roller 12A side of the belt unit 10, the belt unit 10 is attached to the apparatus main body frame 1B with a new configuration different from the invention described in Patent Document 1. And can be assembled detachably.

  In the present embodiment, since the first contacted portion 16B is located on the driven roller 12B side from the second virtual plane S2, when the belt unit 10 is attached and detached, the first contacted portion 16B and the lever member 16A. Can be prevented from interfering with the apparatus main body side frame 1D and the like.

  In the present embodiment, the first contacted portion 16B is provided in a region V1 occupied by the extended virtual belt unit side frame when the belt unit side frame 13 is extended to the gripping portion 15 side. Therefore, a force (pressing force F1) in a direction substantially coincident with the longitudinal direction can be applied to the belt unit side frame 13, and the positioning of the belt unit 10 can be stably held.

  In the present embodiment, the first rib wall 15F and the second rib wall 15G that protrude in the axial direction from the frame wall 15E are provided on the frame wall 15E provided with the first contacted portion 16B of the grip portion 15. Since it is provided, the mechanical strength of the side gripping frame 15A can be improved.

  By the way, since the driving roller 12A rotates without being displaced with respect to the belt unit side frame 13, the driving roller 12A needs to be positioned with higher positional accuracy than the driven roller 12B.

  However, since the material constituting the belt unit side frame 13 (resin in the present embodiment) expands and contracts relatively greatly depending on the temperature, the position of the driving roller 12A may change greatly depending on the temperature.

  On the other hand, in this embodiment, since the second contacted portion 11A is arranged on the driving roller 12A side from the midpoint position between the driven roller 12B and the driving roller 12A, the second contacted portion 11A and the driving roller The distance to 12A can be reduced.

  Therefore, even if the belt unit side frame 13 expands and contracts as the temperature changes, it is possible to prevent the distance between the drive roller 12A and the second contacted portion 11A from expanding or contracting greatly. Can be positioned with high positional accuracy.

  In the present embodiment, since the second contacted part 11A is provided in the belt unit main frame 11, the second contacted part 11A is compared with the case where the second contacted part 11A is provided in the belt unit side frame 13. The position accuracy of the portion 11A can be increased, and the drive roller 12A can be positioned with high position accuracy.

  In the present embodiment, the holding mechanism 16 is provided on the side gripping frame 15A, and the holding mechanism 16 (lever member 16A, spring 16C, etc.) is housed between the first virtual plane S1 and the second virtual plane S2. Therefore, the image forming apparatus 1 can be made smaller than the case where the function corresponding to the holding mechanism 16 is provided on the apparatus main body (apparatus main body side frame 1D) side.

Further, the spring 16C is arranged so that its axial direction is parallel to the direction from the driven roller 12B side toward the tip end side (upper end side) of the gripping portion 15, and therefore the spring 16C has a large axial dimension. However, it can be stored in the space between the first virtual plane S1 and the second virtual plane S2, and the image forming apparatus 1 can be downsized.

  Note that “the axial direction of the spring 16C is parallel to the direction from the driven roller 12B side toward the distal end side of the grip portion 15” is not limited to “parallel” in a strict sense, but visually. This also includes the range of parallelism that seems to be almost parallel.

  In the present embodiment, in the state where the belt unit 10 is mounted on the apparatus main body frame 1B (apparatus main body side frame 1D), the longitudinal direction of the first arm portion 16D and the axial direction of the spring 16C are orthogonal to each other, and Since the longitudinal direction of the second arm portion 16E and the stretching direction of the belt 12C are orthogonal to each other, the pressing force F1 due to the elastic force of the spring 16C can be efficiently applied to the first contact portion 1G.

Note that the term “orthogonal” is not limited to “orthogonal” in a strict sense, but also includes an orthogonality in a range that is considered to be approximately parallel by visual observation.
In the present embodiment, the frame wall 15E has a substantially triangular shape such that the dimension W of the portion parallel to the stretching direction increases from the distal end side (upper end side) of the grip portion 15 toward the driven roller 12B side. Therefore, it is possible to effectively secure a space for storing the holding mechanism 16 while increasing the strength of the grip portion 15 (side grip frame 15A).

(Other embodiments)
In the above embodiment, the image forming apparatus is a direct type that directly transfers the developer image carried on the photosensitive drum 3A onto a sheet. However, the developer image carried on the photosensitive drum 3A is used as an intermediate transfer belt. You may apply to the image forming apparatus of the system which transfers and transfers the developer image transcribe | transferred to the intermediate transfer belt to a paper.

  In the above-described embodiment, the present invention is applied to a color-type image forming apparatus. However, the application of the present invention is not limited thereto, and can be applied to, for example, a monochrome-type image forming apparatus.

In the above-described embodiment, the exposure device using LEDs is used. However, the present invention is not limited to this, and for example, an exposure device that scans laser light may be used.
In the above-described embodiment, the coil spring is used as the spring 16C of the holding mechanism 16. However, the present invention is not limited to this, and other springs such as a torsion spring and a leaf spring may be used.

  In the above-described embodiment, the chute 15D is assembled so that the bridge portion 15B side can swing on the side gripping frame 15A. However, the present invention is not limited to this, and the bridge portion 15B side is the side gripping frame. It may be fixed to 15A.

  In the above-described embodiment, the belt unit main frame 11 and the belt unit side frame 13 are formed as separate bodies and then integrated with screws. However, the present invention is not limited to this, and the belt unit. The main frame 11 and the belt unit side frame 13 may be integrally formed.

  In the above-described embodiment, the conveyance belt 12C is stretched by two rollers including the driving roller 12A and the driven roller 12B. However, the present invention is not limited to this, and three or more rollers are used. The conveyor belt 12C may be stretched.

  Further, the present invention is not limited to the above-described embodiment as long as it meets the gist of the invention described in the claims.

1 is a central sectional view showing a main part of an image forming apparatus 1 according to an embodiment of the present invention. 2 is a central sectional view showing a state in which a top cover 1F of the image forming apparatus 1 is opened. FIG. FIG. 5 is a diagram of a state in which the belt unit is assembled to the apparatus main body frame 1B (image forming apparatus 1) as viewed from the upper surface side. FIG. 3 is a diagram illustrating an arrangement relationship between a process cartridge 3K and the like and a belt unit 10; 2 is a perspective view of a belt unit 10. FIG. FIG. 3 is a perspective view showing a state in which the belt unit 10 is attached / detached. FIG. 3 is a diagram illustrating a state in which the belt unit 10 is detached from the apparatus main body frame 1B (image forming apparatus 1). 3 is a plan view showing the vicinity of a gripping portion 15 of the belt unit 10. FIG. FIG. 9 is a left side view of FIG. 8. 2 is a perspective view showing a state where a belt unit side frame 13 at one end in the width direction is removed from the belt unit 10. FIG. (A)-(c) is a figure which shows the action | operation of chute | shoot 15D provided in the belt unit 10. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 1A ... Paper discharge tray, 1B ... Apparatus main body frame,
1C: housing, 1D: device main body side frame,
1E ... installation groove, 1F ... top cover, 1G ... first contact part,
1H: second contact portion, 1J: reference surface, 1K: reference surface, 1L: width direction positioning portion,
DESCRIPTION OF SYMBOLS 1M ... Width direction positioning part, 2 ... Image formation part, 3A ... Photosensitive drum, 3B ... Transfer roller,
3K ... process cartridge, 4 ... exposure device, 5 ... fixing device, 5A ... heating roller,
6 ... paper feed tray, 7 ... paper feed mechanism, 8 ... paper dust removing roller, 9 ... registration roller,
10 ... belt unit, 11 ... belt unit main frame,
11A ... second contacted part, 11B ... projection, 11C ... projection, 12A ... drive roller,
12B ... driven roller, 12C ... conveying belt, 12D ... elastic member,
13 ... belt unit side frame, 15 ... gripping part,
15A ... side grip frame, 15B ... bridge part, 15C ... opening,
15D ... chute, 15E ... frame wall, 15F ... first rib wall,
15G ... second rib wall, 16 ... holding mechanism, 16A ... lever member,
16B ... 1st contacted part, 16C ... Spring, 16D ... 1st arm part, 16E ... 2nd arm part,
16F ... bent portion, 17 ... electrode portion.

Claims (1)

An image forming apparatus for forming an image on a recording sheet,
A device body frame;
A belt unit main frame, a first roller and a second roller disposed near both ends of the belt unit main frame, and a stretch between the first roller and the second roller. by a belt, and in the belt unit main frame, the first roller and provided in both axial end portion of the second roller, both belt unit side frames extending in stretched direction parallel to the direction of the belt A belt unit having
A side grip frame provided on the first roller side of the belt unit and provided at one end in the longitudinal direction of the belt unit side frames, and an axial direction of the first roller so as to bridge between the side grip frames A gripping portion having a bridge portion extending in the width direction parallel to
A holding mechanism for holding the position of the belt unit with respect to the apparatus main body frame,
The holding mechanism includes a lever member provided with a first contacted part that contacts a first contact part provided on the apparatus main body frame, and a contact surface pressure between the first contacted part and the first contacted part. A coil spring-like elastic means for causing the lever member to act on the lever member.
The lever member has a first arm portion on which the elastic force of the elastic means acts, and a second arm portion on which the first contacted portion is provided, and is bent in a substantially U shape. The bent part is rotatably assembled to the grip part,
In a state where the belt unit is mounted on the apparatus main body frame, the longitudinal direction of the first arm portion and the axial direction of the elastic means are orthogonal to each other, and the longitudinal direction of the second arm portion and the tension of the belt. The rack direction is orthogonal,
The side grip frame has a plate-like frame wall that is orthogonal to a virtual plane parallel to the belt tension portion of the belt and parallel to the longitudinal direction of the belt unit side frame,
Said frame wall the holding mechanism is provided of the front Symbol grippers, the dimensions of the stretched direction parallel to the site as it goes from the leading end side of the grip portion to the first roller side is enlarged, and its The shape seen from the width direction is a triangular shape so that a portion of the edge portion from the first roller side toward the front end side of the gripping portion is inclined,
Furthermore, the elastic means is arranged so that the axial direction thereof is parallel to a portion from the first roller side toward the front end side of the grip portion.

Images