JP4298669B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus represented by a color copying machine or a color printer that forms an image by an electrophotographic system or an electrostatic recording system.

  In a color image forming apparatus, an image bearing member including a photosensitive drum and an intermediate transfer belt has four color toner images such as YMCK (yellow, magenta, cyan, black) carried on the photosensitive drum. Are temporarily transferred onto the surface of the intermediate transfer belt, and the transferred toner images are further transferred onto a recording sheet all at once.

  By the way, when the intermediate transfer belt is replaced or when a jam (paper jam) is generated during operation of the apparatus, the intermediate transfer belt is separated from the steady position in contact with the photosensitive drum and then attached. I do. The reason for removing the intermediate transfer belt after moving it away from the photosensitive drum is to prevent both surfaces from being scratched by rubbing with the photosensitive drum. (See Patent Document 1). On the other hand, in order to insert and remove the intermediate transfer belt from the image forming apparatus main body, it is necessary to provide a belt mounting opening in an outer case or frame of the apparatus main body. However, if such a mounting opening is provided, the rigidity strength of the exterior case and the like will be reduced, so that a structure that can be attached and detached in the direction perpendicular to the generatrix around the drum of the photosensitive drum is also proposed by the present applicant. (See Patent Document 2). Furthermore, at the time of removal, the intermediate transfer belt is separated by dropping in the vertical direction in the vertical direction while maintaining the state as it is. The applicant of the present invention has also proposed a structure in which the intermediate transfer belt separated from the photosensitive drum is pulled out in the direction perpendicular to the bus around the photosensitive drum (the reverse procedure when mounting) (patent) Reference 3).

  Referring to FIGS. 7 to 9, if an example of the intermediate transfer belt attaching / detaching structure is shown, each member of the sheet feeding cassette 1, the pickup roller 2, the feed roller 3, the retard roller 4 and the registration roller 5 is the image forming apparatus main body. It is installed at the bottom. Further, an intermediate transfer belt unit 7 is constituted by using an intermediate transfer belt 7B stretched between driving and driven rollers as a main part, and members such as a tension roller and a secondary transfer roller 6 attached thereto.

  Further, in this case, four photosensitive drums 8 to 11 corresponding to the four colors of YMCK are arranged and exposed on the photosensitive drums by a laser scanner 12 as an exposure means. Further, a fixing device 13, a paper discharge roller 14, and a paper discharge tray 15 are installed at the upper part of the apparatus main body. Further, a separation lever 16 and a positioning roller 17 are provided in the apparatus main body, and a support portion 18 for supporting the intermediate transfer belt unit 7 is provided.

  When operating according to the structure, first, a sheet material such as recording paper fed from the paper feed cassette 1 by the pickup roller 2 is separated one by one by the feed roller 3 and the retard roller 4 so as not to overlap each other. It is conveyed toward the roller 5. Here, the sheet material is temporarily stopped. Subsequently, after the image exposed on the photosensitive drums 8 to 11 by the laser scanner 12 is developed by a developing device (not shown), the developed image is transferred onto the intermediate transfer belt 7B (primary transfer). The image primarily transferred onto the intermediate transfer belt 7B advances in the direction indicated by symbol E in the figure, and the conveyance of the sheet material that is temporarily stopped by the registration roller 5 is resumed as the image advances. The sheet material that has been resumed is transferred by the secondary transfer roller 6 (secondary transfer), the image is fixed by the fixing device 13, and discharged onto the discharge tray 15 by the discharge roller 14.

  When the intermediate transfer belt 7B needs to be replaced due to use over time, the intermediate transfer belt unit 7 is prevented from rubbing against both surfaces due to the intermediate transfer belt 7B rubbing against the photosensitive drums 8 to 11 at the time of removal. The whole is once moved away from the photosensitive drums 8 to 11, and a distance between them is set. That is, the separation lever 16 is rotated in the direction indicated by the arrow A in the drawing, and the positioning roller 17 carrying the support plate 18 of the intermediate transfer belt unit 7 is lowered. By such an operation, the intermediate transfer belt unit 7 is separated from the photosensitive drums 8 to 11 as shown in FIG. After that, the intermediate transfer belt unit 7 is pulled out in the direction indicated by the arrow B in the drawing, and is taken out of the apparatus main body from the outer case.

  On the contrary, as shown in FIG. 9, when the intermediate transfer belt unit 7 is inserted and attached to the apparatus main body, first, the separation lever 16 is rotated in the direction of arrow A, and the positioning roller 17 is lowered. The intermediate transfer belt unit 7 is inserted into the apparatus main body from the direction of arrow C. After the insertion, when the separation lever 16 is rotated in the direction of arrow D, the positioning roller 17 receiving the unit support portion 18 is moved up, the intermediate transfer belt unit 7 is set at the normal position, and the mounting is completed.

JP 2000-235309 A JP2002-131997 JP 2001-117465 A

  By the way, in the above-mentioned patent documents 1 to 3 mentioned regarding the intermediate transfer belt attaching / detaching structure, there are the following common problems a) and b) which are desired to be solved.

  a) Operability of attaching / detaching the intermediate transfer belt unit in two steps.

  When the unit is replaced, the user operates the separation lever 16 to pull down the entire unit downward (up and down operation) to separate it from the photosensitive drum, and then pull it out to the front (horizontal operation) and take it out from the outer case. Requires stage operations. In addition, if the user forgets the presence or operation of such a separation lever 16 and tries to forcibly pull out the intermediate transfer belt unit 7 from the main body of the apparatus, the unit and the photosensitive drums 8 to 11 are likely to rub against each other. There is.

  b) Increase in the number of parts by the pull-out prevention lock mechanism of the intermediate transfer belt unit.

  As described above, in order to prevent the intermediate transfer belt unit 7 from being forcibly pulled out, unless the separation lever 16 is operated, the lock mechanism that locks the intermediate transfer belt unit 7 is not released and cannot be removed. A pull-out prevention lock mechanism is provided. This increases the number of parts.

  In view of the above, an object of the present invention is to provide an image forming apparatus that can improve the detachability of the intermediate transfer belt unit and reduce the number of parts to realize cost reduction.

A representative image forming apparatus of the present invention includes a plurality of rotatable image carriers that carry toner images, and a belt that is detachable from the apparatus main body and onto which toner images are transferred from the plurality of image carriers. In the image forming apparatus, each of the rotation axes of the plurality of image carriers is arranged on a straight line that forms an inclination angle α with respect to a plane parallel to the bottom surface of the apparatus main body. The attachment / detachment direction is a direction parallel to the bottom surface of the apparatus main body, and when the belt unit is detached from the apparatus main body, the leading end of the belt unit in the removal direction is guided to be movable in a direction parallel to the bottom surface of the apparatus main body. And a second guide that is provided in parallel to the first guide member and guides the rear end of the belt unit in the detachment direction so as to be movable in a direction parallel to the bottom surface of the apparatus main body. And characterized by comprising a timber, a can attached to and detached from the plurality of the state where the surface in contact with the image bearing member is maintained the inclination angle α belt unit said plurality of image bearing members of the belt unit To do.

  Therefore, the image forming apparatus having the above configuration attaches and detaches the belt unit from the plurality of image carriers and the main body of the image forming apparatus from a state where the image forming apparatus is in contact with the plurality of image carriers at an inclination angle α. When the belt unit is removed by detaching the belt unit, if the belt unit is moved and pulled out, the belt unit is separated from the image carrier with a widening of the angle range by the inclination angle α without interfering with the plurality of image carriers. That is, the operation of separating the belt unit from the image carrier as described above does not require a two-step operation by lowering and horizontal movement from the conventional one, and is simply pulled out at the time of removal. And when installing, just push in reverse.

  According to the image forming apparatus of the present invention, when the belt unit mounted in the apparatus main body is attached / detached and the attachment / detachment work is performed, the belt unit and the image are taken in and out of the image carrier having the inclination angle α. The carrier is separated from the previous contact state with a spread corresponding to the angle of inclination α relative to the contact state. Therefore, when the belt unit is separated from the image carrier, both surfaces can be prevented from rubbing and the occurrence of scratches or the like can be prevented.

  Hereinafter, a preferred embodiment of an image forming apparatus according to the present invention will be described in detail with reference to the drawings.

(First embodiment)
As shown in FIG. 1, a sheet feeding cassette 21, a pickup roller 22, a feed roller 23, a retard roller 24, and a registration roller 25 including a pair of opposed members are installed at the lower part of the apparatus main body. Further, an intermediate transfer belt unit 27 is provided, and the stretched intermediate transfer belt 27B is in contact with and sandwiched between the secondary transfer roller 26 and the secondary transfer auxiliary roller 27R. The secondary transfer auxiliary roller 27 </ b> R is arranged higher than the secondary transfer roller 26 in the top-down direction with respect to the rotation axis thereof. The intermediate transfer belt 27B is stretched obliquely downward from the secondary transfer roller 26 and the secondary transfer auxiliary roller 27R, that is, obliquely downward from the right side of the drawing to the left side of the drawing.

  Also in this example, there are provided photosensitive drums 28 to 31 which are image carriers for forming and carrying toner images corresponding to four colors of YMCK. The photosensitive drums 28 to 31 have their drum rotation axes positioned on a straight line having an inclination angle α of, for example, 30 ° with respect to the horizontal. Further, as described in the claims, “the belt unit is attached and detached in a direction perpendicular to the rotation axis of the image carrier”, the intermediate transfer belt unit 27 described later is attached to the photosensitive drums 28 to 31. The intermediate transfer belt unit 27 can be smoothly attached and detached without causing interference with the photosensitive drums 28 to 31 by making the attaching and detaching direction to be separated from the drum perpendicular to the drum rotation axis.

  A laser scanner 32 as an exposure means for exposing on the photoreceptors 28 to 31 is provided, and is arranged obliquely downward from the right front side to the left back side in the drawing of the apparatus body so as to coincide with the inclination angle α ° of the intermediate transfer belt unit 27. Has been. A fixing device 33, a pair of opposed paper discharge rollers 34, and a paper discharge tray 35 are installed at the top of the apparatus main body.

  Below the intermediate transfer belt unit 27, an upper guide rail (first guide member) 36 and a lower guide rail (second guide member) 37 are provided in parallel at the vertical position of the apparatus main body. The upper guide rail 36 supports a roller shaft 27a, which is a rotation shaft of the secondary transfer auxiliary roller 27R, so as to be rotatable and horizontally movable in the left-right direction in the drawing. As described in the claims, “a first guide member that rotatably supports one end portion of the belt unit in a rotatable manner and that guides the belt unit so as to be movable in a substantially horizontal direction”. The one end on the higher side refers to the roller shaft 27a supported on the upper guide rail 36, which is a first guide member, so as to be rotatable and movable in a substantially horizontal direction.

  The secondary transfer auxiliary roller 27R having the roller shaft 27a as a rotation axis is a rotation roller on one side where the intermediate transfer belt 27 is stretched, and may be a drive side roller that receives motor rotation power from the drive system of the apparatus main body. it can. The secondary transfer roller 26 is disposed via the intermediate transfer belt 27 at a position facing the secondary transfer auxiliary roller 27R. That is, in the claims, it is configured that “the secondary transfer roller is disposed so as to face the rotating roller at one end on the higher unit side via the intermediate transfer belt”. .

    The inclination of the intermediate transfer belt unit 27, that is, the inclination angle α ′ of the intermediate transfer belt 27B as the main part thereof is the same as or slightly different from the image carrier inclination angle α °, for example, 30 °. Such an inclination angle α ′ is inclined downward toward the back of the main body of the apparatus with the side where the secondary transfer auxiliary roller 27R and the secondary transfer roller 26 are provided at the upper side. By doing so, compared with the structure in which the intermediate transfer belt unit 27 is horizontally arranged, most of the axes of the plurality of photosensitive drums 28 to 31 can be arranged at a lower position with respect to the position of the secondary transfer roller 26. It becomes possible, and the height dimension of the apparatus main body can be kept small and small. By raising the position of the secondary transfer roller 26, it becomes possible to move the position of the secondary transfer roller 26 toward the sheet discharge side in the sheet material conveyance path, and the conveyance path length required after the secondary transfer is shortened. The first printout time can be shortened. For such reasons and effects, in the claims, the secondary transfer auxiliary roller 27R (and the secondary cooperating therewith) such as a drive roller on the higher side of the intermediate transfer belt 27B inclined at the inclination angle α. The arrangement of the transfer roller 26) is described.

  Further, the other end of the intermediate transfer belt unit 27 supported by the lower guide rail 37 that is the second guide member so as to be movable in a substantially horizontal direction is moved horizontally to the lower guide rail 37 that is the second guide member. The support pin 27b is supported in such a way as to be possible (here, it is not essential to support the rotation), and supports the rear left side of the intermediate transfer belt unit 27 in the figure.

  While the intermediate transfer belt unit 27 is provided obliquely with an inclination angle α °, the upper and lower guide rails 36 and 37 extend substantially horizontally. Guided by the upper and lower guide rails 36 and 37, the intermediate transfer belt unit 27 can be moved in a substantially horizontal direction while being inclined, and is shown in the drawing from a unit mounting opening provided on the right side of the apparatus main body. It has a structure that can be moved in and out by moving the distance to a fixed position. The “detaching direction” described in each claim of the present invention refers to it.

  Next, the operation of the first embodiment having the above configuration will be described.

  The sheet material fed from the paper feed cassette 21 by the pickup roller 22 is separated one by one and directed to the registration roller 25 in order to prevent double feeding in which several sheets are overlapped and conveyed by the feed roller 23 and the retard roller 24. Are transported. Here, the sheet material is temporarily stopped.

  The image exposed on the photosensitive drums 28 to 31 by the laser scanner 22 is developed by a developing device (not shown), and is primarily transferred to the intermediate transfer belt 27B. The image (toner image) primarily transferred onto the intermediate transfer belt 27B is advanced in the direction indicated by symbol F in the drawing, and the sheet material that has been temporarily stopped is started to be conveyed again by the registration rollers 25 as the image advances. The secondary transfer roller 26 transfers the image to the sheet material that has been resumed, the image is fixed by the fixing device 23, and then discharged onto the discharge tray 35 by the discharge roller 34.

  Next, as shown in FIGS. 2 and 3, the operation procedure when the intermediate transfer belt unit 27 needs to be replaced and the attachment / detachment operation is performed is as follows.

  The door 38 on the right side in the figure of the apparatus main body is opened, and the intermediate transfer belt unit 27 is guided to the upper and lower guide rails 36 and 37 and taken out in the direction of the arrow indicated by the symbol G in FIG. As the entire intermediate transfer belt unit 27 is pulled out by being guided by the upper and lower guide rails 36, 37, the intermediate transfer belt 27B is naturally separated from the photosensitive drums 28 to 31 that have been in contact with each other. To go. Such natural separation is possible without rubbing the surfaces of each other because the arrangement of the photosensitive drums 28 to 31 is inclined at an inclination angle α ° with respect to the attachment / detachment direction (horizontal) of the intermediate transfer belt unit 27. The inclination angle α ° is that they are separated from each other without any interference.

  Conversely, when the intermediate transfer belt unit 27 is inserted and attached to the apparatus main body, the intermediate transfer belt unit 27 is guided to the upper and lower guide rails 36 and 37 from the opened door 38, and the intermediate transfer belt unit 27 is indicated by an arrow H in FIG. Insert horizontally in the direction. In this case, due to the effect of guiding and holding the upper and lower guide rails 36 and 37, the weight of the intermediate transfer belt unit 27 that is attached and attached does not deviate from the normal fixed position. As a result, the intermediate transfer belt unit 27 can be held in a stable position in the apparatus main body.

(Second Embodiment)
FIG. 4 shows an image forming apparatus according to the second embodiment. If only members and arrangements different from those of the first embodiment are described, the three photosensitive drums 28, 29, and 30 have their drum rotation axes positioned on the same straight line. With respect to the remaining photosensitive drum 31, the intermediate transfer belt 27 </ b> B can be easily separated from the photosensitive drums 28 to 31 by offsetting the rotational axis of the photosensitive drum 31 with the rotational axes of the three photosensitive drums 28, 29, and 30. It is configured to be able to.

  In addition, a guide rail 39 that constitutes a third guide member is provided. The guide rail 39 guides the support pins 27 c and 27 d at both ends of the intermediate transfer belt unit 27, and the three photosensitive drums 28, 29, and 30 are arranged. For example, it is inclined at an angle β = 3 ° with respect to a straight line passing through each drum axis. The support pin 27c is a member that is provided as one end of the unit on the higher side, and is movably guided by the guide rail 39. In the vicinity of the support pin 27c, the intermediate transfer auxiliary roller 27R and the secondary transfer roller 26, which are also shown in the first embodiment as members disposed on the higher unit side, face each other with the intermediate transfer belt 27B interposed therebetween. Is provided. Further, the guide rail 39 is configured so as to be inclined at an angle α = 6 °, for example, with respect to a straight line passing through the drum shafts of the two photosensitive drums 30 and 31 so that α> β.

  Therefore, in the second embodiment, the intermediate transfer belt unit 27 operates as shown in FIGS. 5 and 6 when the intermediate transfer belt unit 27 is attached or detached.

  The side door 8 of the apparatus main body is opened, and the intermediate transfer belt unit 27 is guided by the guide rail 39 and pulled out in the direction of arrow J in FIG. The intermediate transfer belt unit 27 is guided by the guide rail 39 and is drawn obliquely upward. However, the intermediate transfer belt unit 27 is 3 even at the smallest inclination angle with respect to the belt surface of the intermediate transfer belt 27B in contact with the photosensitive drums 28 to 31. Pulled out at an angle of °. Therefore, the intermediate transfer belt 27B is naturally separated from the photosensitive drums 28 to 31 and forms a clearance with the photosensitive drum.

  Conversely, when the intermediate transfer belt unit 27 is inserted and attached to the apparatus main body, the intermediate transfer belt unit 27 is inserted obliquely in the direction of the arrow K in FIG. . In this case, when the intermediate transfer belt unit 27 is inserted by being guided by the guide rail 39, the intermediate transfer belt unit 27 is moved from the inclined upper side to the lower direction. Therefore, there is an effect of retaining without deviating from the regular home position, and it is stably held in the apparatus main body.

  In the second embodiment, the only member that guides the movement of the intermediate transfer belt unit 27 in the attaching / detaching direction is the guide rail (third guide member) 39. In the first embodiment, as shown in FIG. Two of the constructed upper and lower guide rails 36 and 37 are not required. This is effective in that the apparatus main body can be reduced in size in the height direction.

  The first and second embodiments have been described above. However, the present invention is not limited to these embodiments as long as they do not depart from the gist of the present invention, and other modifications and application examples by other embodiments and combinations thereof. Is also possible.

1 is a cross-sectional view showing a first embodiment of an image forming apparatus according to the present invention. FIG. 3 is a cross-sectional view illustrating a mode in which an intermediate transfer belt unit is removed in the first embodiment. Sectional drawing which shows the aspect which pulled out the intermediate transfer belt unit out of the apparatus main body in the embodiment. Sectional drawing which shows 2nd Embodiment of the image forming apparatus by this invention. Sectional drawing which shows the aspect which removes an intermediate transfer belt unit in 2nd Embodiment. Sectional drawing which shows the aspect which inserts and mounts an intermediate transfer belt unit in an apparatus main body in the same embodiment. FIG. 5 is a cross-sectional view illustrating a pulling operation when an intermediate transfer belt unit is taken out in an image forming apparatus that is an example of background art. Sectional drawing which shows horizontal extraction operation at the time of taking out an intermediate transfer belt unit in the image forming apparatus of the background art. Sectional drawing which shows the aspect which inserts and mounts an intermediate transfer belt unit in an apparatus main body in the image forming apparatus of the background art.

Explanation of symbols

26 Secondary transfer roller 27 Intermediate transfer belt unit 27B Intermediate transfer belt 27R Secondary transfer auxiliary roller 27a Roller shaft (one end on the higher unit side)
27c Support pin (one end on the higher side of the unit)
27b, 27d Support pin (the other end on the lower side of the unit)
28-31 Photosensitive drum (image carrier)
36 Upper guide rail (first guide member)
37 Lower guide rail (second guide member)
39 Guide rail (third guide member)

Claims (3)

A plurality of rotatable image carriers that carry a toner image; and a belt unit that is detachably attached to the apparatus main body and from which the toner images are transferred. In the image forming apparatus in which the respective rotation axes of the plurality of image carriers are arranged on a straight line having an inclination angle α with respect to a plane parallel to the surface,
The direction in which the belt unit is attached / detached is parallel to the bottom surface of the apparatus main body, and when the belt unit is detached from the apparatus main body, the front end of the belt unit in the removal direction is in a direction parallel to the bottom surface of the apparatus main body. A first guide member that is movably guided, and is provided in parallel to the first guide member, and guides the rear end of the belt unit in the detachment direction so as to be movable in a direction parallel to the bottom surface of the apparatus main body. The belt unit can be attached to and detached from the plurality of image carriers in a state where the surface of the belt unit that contacts the plurality of image carriers maintains the inclination angle α. An image forming apparatus. A plurality of rotatable image carriers that carry a toner image; and a belt unit that is detachably attached to the apparatus main body and from which the toner images are transferred. In the image forming apparatus in which the respective rotation axes of the plurality of image carriers are arranged on a straight line having an inclination angle α with respect to a plane parallel to the surface,
The belt unit is detachable in a direction parallel to the bottom surface of the apparatus main body, and is movable in a direction that forms an inclination angle β smaller than the inclination angle α with respect to a plane parallel to the bottom surface of the apparatus main body. A guide member for guiding is provided, and the belt unit can be attached to and detached from the plurality of image carriers in a state where the surface of the belt unit that contacts the plurality of image carriers maintains the inclination angle α. An image forming apparatus. The image forming apparatus according to claim 1, wherein a front end portion of the belt unit in the detaching direction is a rotating roller that stretches and rotates the belt unit .

Images