JP2008276094A - Developing device and image forming apparatus having same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily ensure a gap between a magnetic roll and a developing roll with high accuracy. <P>SOLUTION: The magnetic roll 44 (illustrated only the center) and its one end are held by a bearing and its other end is held by a bearing member 74. In this stage, the gap between the surface of the magnetic roll 44 and the surface of the developing roll is measured. If the result of the measurement does not satisfy a predetermined value, replacement with a roller combination satisfying the value is carried out. The one bearing member holding the magnetic roll 44 and developing roll 45, and the other bearing member 74 are engaged with bearing support notches 78 or the like, such as the boss supports 76 of a development container. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a developing device having a magnetic roll carrying a two-component developer on its surface, and a developing roll for carrying the development by carrying toner supplied from the magnetic roll on the surface, and image formation provided therewith Relates to the device.

  A developing device used in an image forming apparatus such as a printer, a copying machine, a facsimile machine, etc., which uses a two-component developer and develops an electrostatic latent image on the surface of a photosensitive drum with toner using a magnetic roll and a developing roll. Are known (for example, Patent Documents 1 and 2). A magnetic brush of a two-component developer is formed on the surface of the magnetic roll, and the developing roll is rubbed with the magnetic brush to form a thin layer of toner on the surface of the developing roll. The electrostatic latent image is developed.

  In this type of developing device, it is essential to maintain a gap between the surface of the magnetic roll and the surface of the developing roll (hereinafter referred to as “inter-roll gap”) with high accuracy. When the gap between the rolls fluctuates, the layer thickness of the toner carried on the surface of the developing roll becomes non-uniform, and the density of toner present on the surface of the photosensitive drum developed by this toner becomes non-uniform.

Therefore, in Patent Documents 1 and 2, one end portion of the magnetic roll and the developing roll is supported at a predetermined inter-axis pitch by one bearing member, and the other end portion is supported at the same inter-axis pitch by the other bearing member. Like to do. That is, both ends of the magnetic roll and the developing roll are supported by the pair of bearing members at the same inter-axis pitch. Thereby, the magnetic roll and the developing roll are assembled with high assembly accuracy, and the gap between the rolls is ensured with high accuracy.
JP 2003-167424 A JP 2003-337472 A

  However, since there is a manufacturing error in the magnetic roll and the developing roll, even if both ends of the magnetic roll and the developing roll are held at a high inter-axis pitch as in the above-described prior art, the gap between the rolls is actually Will vary. Variations in this case include those due to the coaxiality, roundness, etc. of both rollers that occur as both rollers rotate. In either case, after assembling the magnetic roll and the developing roll, if the gap is measured and the desired accuracy cannot be ensured, it is necessary to replace at least one of the rolls and change the combination. In this case, it is very difficult and time consuming to measure the gap between rolls after assembly.

  As one measure for solving such difficult work, before assembling the magnetic roll and the developing roll into the developing device, the gap between the rolls is preliminarily attached to the same bearing member as that incorporated in the developing device. It is conceivable to measure in According to this, the measurement becomes easy, and it is possible to determine a good combination of the magnetic roll and the developing roll by simply exchanging the roll according to the measurement result.

  However, in this case, it is necessary to remove the magnetic roll and the developing roll from the bearing member for measurement in advance and attach them again to the bearing member incorporated in the developing device. In this case, if a combination of rolls that has achieved a good gap between rolls in a prior measurement is assembled to the bearing member of the developing device, the desired gap between rolls may not be secured. is there.

  Therefore, in the present invention, the magnetic roll and the developing roll are attached to the developing container while being held by the pair of bearing members, so that the gap between the rolls can be secured with high accuracy and easily. An object of the present invention is to provide a developing device and an image forming apparatus including the developing device.

  According to a first aspect of the present invention, there is provided a developer agitating chamber for accommodating and agitating a two-component developer having a toner and a carrier, and a magnetic material for carrying and carrying the developer supplied from the developer agitating chamber on the surface. The present invention relates to a developing device comprising: a roll; and a developing roll that carries the toner supplied from the developer on the surface of the magnetic roll, conveys the toner, and adheres it to an electrostatic latent image on an image carrier. The developing device according to the present invention includes a developer container having the developer agitating chamber, a magnetic roll storage chamber for storing the magnetic roll, and a developing roll storage chamber for storing the developing roll, and the magnetic roll and the developing roll. A pair of bearing members comprising one bearing member supporting one end portion at a predetermined pitch and the other bearing member supporting the other end portion of the magnetic roll and the developing roll at the predetermined pitch; The magnetic roll and the developing roll are attached to the developing container by mounting the pair of bearing members in a state of holding the magnetic roll and the developing roll at predetermined positions of the developing container. It is characterized by that.

  According to a second aspect of the present invention, in the developing device according to the first aspect, the developer container is provided with the developer stirring chamber, the magnetic roll storage chamber, and the development roll storage chamber in order from the upper side. It is characterized by.

  According to a third aspect of the present invention, in the developing device according to the first or second aspect, the pair of bearing members each have a cylindrical bearing boss portion coaxial with the magnetic roll, and the developing container is the bearing It has the boss | hub support part in which a pair of bearing support hole which supports a boss | hub part rotatably was formed, It is characterized by the above-mentioned.

  According to a fourth aspect of the present invention, in the developing device according to the third aspect, at least one of the boss support portions is the boss portion with respect to the bearing support hole from a direction orthogonal to a central axis of the bearing support hole. It has the opening part which enables engagement / disengagement of this.

  According to a fifth aspect of the present invention, in the developing device according to the fourth aspect, the opening has a width dimension shorter than the diameter of the bearing support hole, and the bearing boss has a width dimension at a part thereof. It has the notch part formed shorter than the width dimension of the said opening part, It is characterized by the above-mentioned.

  According to a sixth aspect of the present invention, in the developing device according to the fifth aspect, the direction of the opening is after the notch is passed through the opening and the bearing boss is engaged with the bearing support hole. The bearing member is set in a direction in which the bearing member can be disposed at the mounting position by lowering the developing roll side of the bearing member downward.

  According to a seventh aspect of the present invention, in the developing device according to any one of the first to sixth aspects, the magnetic roll storage chamber of the developing container faces the surface of the magnetic roll via a minute gap. A layer thickness regulating member having a distal end portion is provided.

  According to an eighth aspect of the present invention, in the developing device according to any one of the first to seventh aspects, the surface of the developing roller and the surface of the image carrier are brought into contact with the surface of the image carrier. An annular spacer that holds the gap in a predetermined size is attached to the developing roll.

  According to a ninth aspect of the present invention, there is provided an image carrier on which an electrostatic latent image is formed on a surface, a developing device that develops the electrostatic latent image with toner, and a toner image formed on the surface of the image carrier. The present invention relates to an image forming apparatus including a transfer device that transfers to a sheet. The image forming apparatus according to the present invention is characterized in that the developing device is the developing device according to any one of claims 1 to 8.

  According to the invention of claim 1, since the gap between the magnetic roll and the developing roll (gap between the rolls) can be measured before being incorporated in the developing container in a state where they are held by the bearing member, The roller can be easily replaced based on the measurement and the measurement result. Further, since the pair of bearing members holding the magnetic roll and the developing roll are mounted at predetermined positions of the developing container, the accuracy before mounting can be ensured even after mounting.

  According to the second aspect of the present invention, the developer agitating chamber, the magnetic roll storage chamber, and the development roll storage chamber are arranged in order from the upstream side along the flow of the developer or toner. The flow of the agent and toner can be made smooth.

  According to invention of Claim 3, a magnetic roll can be assembled | attached with high precision via a bearing member with respect to a developing container.

  According to the invention of claim 4, since the boss portion of the bearing member can be engaged with the bearing support hole of the boss support portion through the opening, the boss portion is axially disposed with respect to the bearing support hole. Compared with the case where it is engaged with, the engagement operation is easy.

  According to the fifth aspect of the present invention, the boss portion is prevented from being detached from the bearing support hole by rotating the bearing member after passing the opening and engaging the boss portion of the bearing member with the bearing support hole. Can be.

  According to the invention of claim 6, after the boss portion is engaged with the bearing support hole, the boss portion is not detached from the bearing support hole by lowering the developing roll side of the bearing member downward and disposing it at the mounting position. Can be.

  According to the invention of claim 7, since the magnetic roller is positioned via the bearing member with respect to the developing container, the gap (gap) between the surface of the magnetic roller and the tip of the layer thickness regulating member is high. It can be ensured with accuracy.

  According to the eighth aspect of the present invention, a gap (gap) between the surface of the developing roll and the surface of the image carrier can be ensured with high accuracy.

  According to the ninth aspect of the present invention, the image forming apparatus can achieve the effects of the first to eighth aspects.

  Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings. In addition, in each drawing, the member etc. which attached | subjected the same code | symbol are the same structures, The duplication description about these shall be abbreviate | omitted suitably. Moreover, in each drawing, members and the like that are not necessary for the description are omitted as appropriate.

<Embodiment 1>
With reference to FIG. 1, the image forming apparatus 1 provided with the developing device 31 according to the present invention will be described. FIG. 1 is a diagram schematically illustrating an internal configuration of the image forming apparatus 1 as viewed from the left side. Here, examples of the image forming apparatus 1 include a printer, a copier, a facsimile, and a complex machine of these. In the following description, an image formation is performed using an electrophotographic tandem four-color full-color printer as an example. The device 1 will be described.

  The image forming apparatus 1 includes an image forming apparatus main body 2 formed in a substantially rectangular parallelepiped shape. The image forming apparatus main body 2 includes a sheet feeding unit 3, an image forming unit 4, a fixing unit 5, and a sheet discharging unit 6. Is provided.

  The sheet feeding unit 3 includes a plurality of sheet feeding cassettes 10, pickup rollers 11 and feeding rollers 12 corresponding to the respective sheet feeding cassettes 10, a conveying guide 13, a conveying roller pair 14, and conveying rollers 15. A pair of registration rollers 16 and the like are disposed. In the three paper feed cassettes 10, a plurality of sheets P having different sizes and orientations are stored in a stacked state. The uppermost sheet P in the sheet feeding cassette 10 is fed by the pickup roller 11 and the feeding roller 12, and is conveyed downstream along the conveyance guide 13 by the conveyance roller pair 14 and the conveyance roller 15. The front end of the conveyed sheet P is brought into contact with the nip portion of the stopped registration roller pair 16 to correct skewing and is temporarily stopped. The sheet P is supplied to the conveying belt 20 of the image forming unit 4 described below by the subsequent rotation of the registration roller pair 16.

  The image forming unit 4 includes a transport belt 20 that moves endlessly in the front-rear direction, and four (four colors) that are sequentially arranged from the upstream side to the downstream side along the rotation direction (arrow R20 direction). Image forming stations, that is, image forming stations 21, 22, 23, and 24 for each color of yellow, magenta, cyan, and black are provided.

  The conveying belt 20 is stretched between a downstream driving roller 25 and an upstream driven roller 26, and the surface of the sheet P supplied from the sheet feeding unit 3 is rotated by the rotation of the driving roller 25. And rotate in the direction of arrow R20.

  Since the four-color image forming stations 21, 22, 23, and 24 have the same configuration and operation, the yellow image forming station 21 will be described below, and description of the other colors will be omitted. The yellow image forming station 21 is provided with a photosensitive drum 27 as an image carrier so as to be in contact with the conveying belt 20. The photosensitive drum 27 is rotationally driven at a predetermined process speed (circumferential speed) in the direction of the arrow by a driving unit (not shown). The surface of the photosensitive drum 27 is uniformly charged to a predetermined polarity and potential by the charging device 28, and the exposure portion 30 removes the charge of the exposed portion based on the image information to form an electrostatic latent image. The electrostatic latent image is developed as a toner image with yellow toner attached thereto by the developing device 31. Above the developing device 31, there is disposed a toner container 32 that stores toner to be supplied to the developing device 31 when the amount of developer in the developing device 31 decreases. The developing device 31 will be described in detail later.

  Similarly, in the image forming stations 22, 23, and 24 of three colors other than yellow, magenta, cyan, and black toner images are respectively formed on the surface of the photosensitive drum 27. The toner images of the respective colors formed on the surfaces of the respective photosensitive drums 27 are transferred by the transfer device 33 when the sheets P carried on the surface of the conveying belt 20 sequentially pass through the photosensitive drums 27 by the rotation of the conveying belt 20. Sequentially transferred and superposed on the surface of the sheet P. Note that the toner (transfer residual toner) remaining on the surface of the photosensitive drum 27 after the toner image has been transferred is removed by the cleaning device 34 and used for the next image formation.

  The fixing unit 5 is provided with a fixing roller 35 incorporating a heater (not shown) and a pressure roller 36 pressed against the fixing roller 35 from below, and a fixing nip is provided between the two rollers. The part is composed. The sheet P on which the toner image has been transferred to the surface by the image forming unit 4 is heated and pressurized when passing through the fixing nip portion, and the toner image is melted and fixed (fixed) on the surface.

  The sheet discharge unit 6 is provided with a conveyance roller pair 37, a discharge roller pair 38, a discharge tray 40, and the like. In the fixing unit 5 described above, the sheet P having the toner image fixed on the surface thereof is conveyed by the conveying roller pair 37 and discharged by the paper discharge roller pair 38 face down on the paper discharge tray 40 with the image surface facing downward. Is done. The four-color full-color image formation on one side (front surface) of one sheet P is thus completed.

  Next, the developing device 31 according to the present invention will be described with reference to FIGS. Among these, FIG. 2 is a diagram schematically showing a configuration inside the developing device 31 as viewed from the left side. 3A is a perspective view of the developing device 31 showing a state in which the rear side wall 47 located on the photosensitive drum 27 side of the developing container 41 is removed. FIG. 4B is a perspective view showing the removed magnetic roll 44 and developing roll 45 in a state where the positional relationship when being incorporated in the developing container 41 is maintained. FIG. 4 is a perspective view for explaining a bearing support hole 77 with which one bearing member 73 is engaged. FIG. 5 is a perspective view illustrating a bearing support notch hole 78 with which the other bearing member 74 is engaged. FIG. 6A is a perspective view illustrating a state in which one bearing member 73 is engaged with the bearing support hole 77. FIG. 6B is a perspective view illustrating one bearing member 73 engaged with the bearing support hole 77. FIG. 7A is a perspective view for explaining the other bearing member 74 engaged with the bearing support notch hole 78. FIG. 6B is a perspective view illustrating a state in the middle of engaging the other bearing member 74 with the bearing support notch hole 78. FIG. 8 is a perspective view for explaining a state in which the other bearing member 74 is engaged with the bearing support notch hole 78 and then rotated so as not to come out. 7 and 8, the magnetic roll 44 is not shown for convenience of explanation.

  As shown in FIG. 2, the developing device 31 is disposed on the front side (right side in the drawing) of the photosensitive drum 27, and includes a developing container (frame body) 41 that stores the developer, and an inner side of the developing container 41. 4, ie, a stirring mixer 42, a paddle mixer 43, a magnetic roll 44, and a developing roll 45. Here, in the present invention, the developer is composed of a magnetic carrier and a nonmagnetic toner (synthetic resin powder) as main components, and an external additive such as a charge accelerator is appropriately added. A component developer is used.

  The developing container 41 has a front side wall 46 and a rear side wall 47 that are bent upward and are long in the left-right direction, and a left side wall 48 and a right side wall 50 that are disposed on the left end side and the right end side, respectively. As a whole, it is formed in a cylindrical shape that rises forward. The developing container 41 has an opening 51 to which the above-described toner container 32 is attached on the upper side, and has an opening 52 facing the surface of the photosensitive drum 27 on the lower side. , 52 is formed with an internal space that is inclined obliquely downward from the upper side to the rear side. This internal space is directly used as the moving direction of the developing device 31. The upper opening 51 is closed by the bottom of the toner container 32 described above. The toner container 32 is provided with a toner supply port (not shown) and a shutter (not shown) for opening and closing the toner supply port (not shown) at a position corresponding to the left side of a stirring mixer storage chamber 53 to be described later. When the shutter is released, the toner in the toner container 32 is supplied to the agitating mixer storage chamber 53.

  In the internal space, a stirring mixer storage chamber 53, a paddle mixer storage chamber 54, a magnetic roll storage chamber 55, and a developing roll storage chamber 56 are provided in this order from the upper front side. Among these, the stirring mixer storage chamber 53 and the paddle mixer storage chamber 54 constitute a developer stirring chamber. A partition plate 57 is provided between the stirring mixer storage chamber 53 and the paddle mixer storage chamber 54. A developer circulation hole window (not shown) is formed in the right end side and the left end side of the partition plate 57. As will be described later, in the right developer distribution window, the developer distribution hole window is connected to the stirring mixer storage chamber 53. The developer moves from the paddle mixer chamber 54 to the agitating mixer storage chamber 53 in the opposite direction to the paddle mixer storage chamber 54 and in the developer distribution window on the left side. A developer sensor 58 is attached to the upper end side of the front side wall 46 toward the stirring mixer 42. The developer sensor 58 detects the amount of developer in the agitating mixer storage chamber 53. When a predetermined amount or less is detected, toner is supplied from the toner container to the agitating mixer storage chamber 53. It has become. In the magnetic roll storage chamber 55, a spike cutting blade (layer thickness regulating member) 60 is disposed. The gap cutting blade 60 has a gap G1 between its tip and the outer peripheral surface of the magnetic roll 44 set to, for example, about 0.3 to 1.5 mm, and is thus carried on the surface of the magnetic roll 44. The layer thickness of the developer is regulated.

  As shown in FIG. 3A, the stirring mixer 42 has a rotating shaft 61 and a screw 62 formed in a spiral around the rotating shaft 61, and is disposed in the stirring mixer storage chamber 53 of the developing container 41. Yes. The developer in the stirring mixer storage chamber 53 is conveyed while being stirred from the left end side to the right end side by the rotation of the stirring mixer 42, and moves to the paddle mixer storage chamber 54 through the flow developer passage on the right side.

  The paddle mixer 43 is constituted by a rotation shaft (not shown) and a blade portion (not shown) attached around the rotation shaft. By the rotation, the developer in the paddle mixer storage chamber 54 is moved from the right end side to the left end side. It is supplied to the magnetic roll 44 while being conveyed. The developer is conveyed while being agitated by the agitating mixer 42 and the paddle mixer 43, so that the developer is triboelectrically charged and given a tribo.

  The magnetic roll 44 includes a columnar magnet 63 and a cylindrical sleeve 64 that rotates around the outer peripheral surface thereof. The magnet 63 has a plurality of magnetic poles arranged in the circumferential direction, and causes the carrier in the developer to stand on the surface of the sleeve 64 by magnetism. The toner is electrically held on the spiked carrier. Thus, the magnetic brush formed on the surface of the sleeve 64 (hereinafter referred to as “the surface of the magnetic roll 44”) is cut off when passing through the above-described cutting blade 60, and the layer thickness is regulated.

  The developing roll 45 is disposed in the developing roll storage chamber 56 of the developing container 41, and a part of the developing roll 45 projects rearward from the opening 52 of the developing container 41 so as to face the surface of the photosensitive drum 27. Yes. A gap G3 between the surface of the developing roll 45 and the surface of the photosensitive drum 27 is held at 150 to 400 μm by gap pulleys (spacers) 82 and 85 described later. More preferably, the thickness is 200 to 300 μm. If the gap G3 is narrower than 150 μm, it causes fogging. Conversely, if the gap G3 is larger than 400 μm, it is difficult to cause the toner to fly from the developing roll 45 to the photosensitive drum 27 in jumping development, thereby obtaining a sufficient image density. In addition, a phenomenon called selective development in which only toner having a certain particle diameter or more is caused to occur. On the other hand, the gap G <b> 2 between the surface of the magnetic roll 44 and the surface of the developing roll 45 is held at 0.3 to 1.5 mm, which is the same as the gap G <b> 1 between the magnetic roll 44 and the ear cutting blade 60 described above.

  The above four rotating bodies, that is, the stirring mixer 42, the paddle mixer 43, the magnetic roll 44, and the developing roll 45 are rotatably supported on the left side wall 48 and the right side wall 50 of the developing container 41 via bearings and the like. The image forming apparatus main body 2 is driven to rotate by a drive motor (not shown) via a gear train or the like.

  Here, the rotation of the magnetic roll 44 and the developing roll 45 will be described. A drive gear (not shown) is attached to the right end side (left side in the figure) of the magnetic roll 44 shown in FIG. 3A, and the drive motor on the image forming apparatus main body 2 side is attached to this drive gear. The rotation is transmitted from. Further, as shown in FIG. 3A, a gear train 65 is formed on the outer side of the bearing member 74 on the left end side of the magnetic roll 44. A transmission gear 66 is fixed to the left end of the central shaft 44 b of the magnetic roll 44, and a transmission gear 67 having a smaller diameter is fixed adjacent to the inside of the transmission gear 66. The rotation of the magnetic roll 44 is transmitted to the paddle mixer 43 and the agitation mixer 42 via the transmission gear 66. An idle gear 68 is engaged with the small-diameter transmission gear 67, and a developing roll gear 70 fixed to the left end of the central shaft 45 b of the developing roll 45 is engaged with the idle gear 68. Thereby, when the magnetic roll 44 rotates in the direction of the arrow in FIG. 2, the developing roll 45 rotates in the direction of the arrow. That is, the surface of the magnetic roll 44 and the surface of the developing roll 45 move in the opposite directions in the gap G2 facing each other.

  In the developing device 31 described above, the developer in the agitation mixer storage chamber 53 is agitated by the agitation mixer 42 so as to be charged, and is supplied to the paddle mixer storage chamber 54 through the developer distribution window on the right side. Moved. The moved developer is further stirred by the paddle mixer 43 to be charged, and supplied to the magnetic roll 44. The supplied developer forms a magnetic brush by the magnetic roll 44, the layer thickness is regulated by the ear cutting blade 60, and is conveyed to the gap G <b> 2 by the rotation of the magnetic roll 44. A DC bias is applied to the magnetic roll 44 by a power source 71, and a DC bias and an AC bias are applied to the developing roll 45 by a power source 72. Of the developer conveyed to the gap G <b> 2 by the rotation of the magnetic roll 44, the toner is transferred from the magnetic roll 44 to the developing roll 45 by the potential difference ΔV of the DC bias by the power sources 71 and 72 described above. The transferred toner is carried in a thin layer state on the surface of the developing roll 45, and is conveyed to a gap G3 (developing position) facing the surface of the photosensitive drum 27 by the rotation of the developing roll 45, and jumping development is performed. That is, the DC bias and the AC bias applied to the developing roll 45 fly to the surface of the photosensitive drum 27 and are attached to the electrostatic latent image.

  The layer thickness of the toner carried on the surface of the developing roll 45 varies depending on the resistance of the developer, the speed difference between the magnetic roll 44 and the developing roll 45, the potential difference ΔV, and the like, and these values are appropriately controlled. By doing so, a desired layer thickness can be obtained. For example, when the potential difference ΔV is increased, the layer thickness is increased, and when the potential difference ΔV is decreased, the layer thickness is decreased. In general, the potential difference ΔV is preferably about 100 to 250V.

  Each gap in the developing device 31 described above, that is, the gap G1 between the tip of the cutting blade 60 and the surface of the magnetic roll 44, the gap G2 between the surface of the magnetic roll 44 and the surface of the developing roll 45, and the developing roll 45 When the gap G3 between the surface and the surface of the photosensitive drum 27 cannot be ensured with high accuracy, a good image density cannot be obtained.

  Therefore, in the present invention, among these three gaps G1, G2, and G3, the gap G2 between the surface of the magnetic roll 44 and the surface of the developing roll 45 can be easily secured with high accuracy. Hereinafter, this point will be described in detail. In the present embodiment, the other two gaps G1 and G3 are configured to ensure high accuracy. This point will also be described later.

  One of the features of the present invention is that the pair of bearing members 73 and 74 are positioned and attached to the developing container 41 while the magnetic roll 44 and the developing roll 45 are held by the pair of bearing members 73 and 74. The gap G2 between the magnetic roll 44 and the developing roll 45 is ensured with high accuracy.

  FIG. 3A shows the developing device 31 with the rear side wall 47 removed as described above, and FIG. 3B shows the magnetic roll 44 and the developing roll 45 while maintaining the positional relationship of FIG. The state which took out is shown. As shown in (b), center shafts 44a and 45a project from the right end sides of the magnetic roll 44 and the developing roll 45, respectively, and center shafts 44b and 45b project from the left end side, respectively. As shown in (a), the right central shaft (one end portion) 44a, 45a is supported by the right bearing member (one bearing member) 73, and the left central shaft (the other end portion) 44b45b. Is supported by the left bearing member (the other bearing member) 74.

  As shown in FIGS. 4 and 5, in the present embodiment, the developing container 41 includes a front side wall 46, a right side wall 50, and a left side wall 48 that are integrally formed. The boss support portions 75 and 76 are formed at positions corresponding to each other. Among these, as shown in FIG. 4, the right boss support portion 75 is provided with a circular bearing support hole 77. In this bearing support hole 77, a cylindrical bearing boss portion 80 protruding from the outer side surface (right side surface) of a right bearing member 73 described later is engaged in the direction of arrow a. On the other hand, as shown in FIG. 5, the left boss support portion 76 has a bearing support notch hole 78 having a hole portion 78a having the same diameter as the above-described bearing support hole 77 and an opening portion 78b communicating with the hole portion 78a. Is formed. The opening 78b is formed substantially toward the rear (photosensitive drum 27 side). The width L1 of the opening 78b is set smaller than the diameter of the hole 78a. This is to prevent the bearing boss 83 of the bearing member 74 once engaged with the hole 78a from dropping off as will be described later.

  As shown in FIGS. 6A and 6B, the right bearing member 73 is a support portion (not shown) that holds the right central shaft 44a of the magnetic roll 44 and the right central shaft 45a of the developing roll 45, respectively. The central shafts 44a and 45b are supported at a predetermined inter-axis pitch P1. Further, a bearing boss portion 80 concentric with the central shaft 44a is provided on the outer surface of the bearing member 73 on the magnetic roll 44 side so as to protrude outward. In addition, a disk-shaped recess 81 is formed on the outer side of the bearing member 73 on the developing roll 45 side. The recess 81 houses a disc gap pulley (spacer) 82 attached to the central shaft 45a. The diameter of the gap pulley 82 is set slightly larger than the diameter of the developing roll 45 and is concentric with the developing roll 45. A notch 81a is provided on the rear end side of the recess 81, and the gap pulley 82 exposes a part 82a from the notch 81a. The part 82a is exposed to the photosensitive drum 27. Is in contact with a non-image forming area (not shown) outside the image forming area in the axial direction.

  On the other hand, as shown in FIGS. 7A and 7B, the left bearing member 74 has a left central shaft 44b of the magnetic roll 44 (shown by a one-dot chain line in the drawing) and a left side of the developing roll 45. Each of the central shafts 44b and 45b is supported at a predetermined inter-pitch pitch P1. Further, a bearing boss portion 83 concentric with the central shaft 44b is projected inwardly on the inner surface of the bearing member 74 on the magnetic roll 44 side. The bearing boss portion 83 is formed with notches 83a at two locations, and the width dimension L2 between the notches 83a and 83a is slightly smaller than the width dimension L1 of the opening 78b of the boss support portion 76 described above. Is set to a small value. The direction of the notch 83a (the direction perpendicular to the width direction) is directed in substantially the same direction as a straight line connecting the central axis 44b of the magnetic roll 44 and the central axis 45b of the developing roll 45, and this direction is described later. As shown, the direction substantially coincides with the direction in which the bearing boss 83 is inserted (the direction of the arrow b). Further, on the developing roller 45 side of the left bearing member 74, a recess 84 and a notch 84a similar to the recess 81 and the notch 81a of the left bearing member 73 described above are formed. A gap pulley 85 that is paired with the above-described gap pulley 82 is housed in a state of being attached to the central shaft 45b. A part 85a of the gap pulley 85 is exposed from the notch 84a and brought into contact with the surface of the photosensitive drum 27. Yes.

  In the present invention, in the developing device 31 having the above-described configuration, the magnetic roll 44 and the developing roll 45 are held in advance by the pair of bearing members 73 and 74, and the pair of bearing members 73 and 74 in the held state are held in the developing container 41. It is trying to be attached to. That is, as shown in FIG. 6B, the right central shafts 44 a and 45 a of the magnetic roll 44 and the developing roll 45 are inserted into the support portion (not shown) of the right bearing member 73. On the other hand, as shown in FIG. 7A, the left central shafts 44 b and 45 b of the magnetic roll 44 and the developing roll 45 are inserted into the support portion of the left bearing member 74. Thereby, the magnetic roll 44 and the developing roll 45 can be held by the pair of bearing members 73 and 74. In this state, the gap G2 between rolls is measured. When the gap G2 between the rolls satisfies a desired value by this measurement, the pair of bearing members 73 and 74 in this state are attached to the developing container 41. On the other hand, even if the magnetic roll 44 and the developing roll 45 are each within a predetermined tolerance as a single product, the gap G2 between the rolls formed between the two does not satisfy a desired value. There is. In this case, at least one is replaced with another, and the inter-roll gap G2 is measured again. The same operation is performed until the combination of the magnetic roll 44 and the developing roll 45 that satisfies a desired value is determined. Thereafter, gap pulleys 82 and 85 are attached to the central shafts 45 a and 45 b on both sides of the developing roll 45, respectively, and stored in the recesses 81 and 84 of the bearing members 73 and 74.

  In this state, the bearing members 73 and 74 on both sides are attached to the developing container 41. First, the bearing members 73 and 74 on both sides are held with the left and right hands so that the magnetic roll 44 and the developing roll 45 have substantially the same height. As a result, as shown in FIG. 7B, the orientation of the notches 83a and 83a of the bearing boss 83 of the bearing member 74 and the orientation of the opening 78b of the boss support 76 are substantially the same. Next, as shown in FIG. 7B, the bearing boss 80 of the right bearing member 73 from the direction of arrow a shown in FIG. 4 is inserted into the bearing support hole 77 of the boss support 75 of the left side wall 50. Then, the bearing boss portion 83 of the left bearing member 74 is moved in the direction of the arrow b to pass the opening 78b of the boss support portion 76 of the left side wall 48. Accordingly, the right and left bearing boss portions 80 and 83 can be engaged with the bearing support hole 77 and the bearing support notch hole 78, respectively. Next, the bearing members 73 and 74 on both sides are moved downward on the developing roll 45 side with reference to the bearing boss portions 80 and 83, and are arranged at predetermined positions shown in FIG. As a result, the positions of the notch 83 a and the opening 78 b of the bearing boss 83 are shifted, so that the bearing boss 83 does not fall out of the bearing support notch hole 78. The bearing members 73 and 74 arranged at predetermined positions are urged toward the photosensitive drum 27 on the developing roll 45 side by an urging member (not shown). As a result, the gap pulleys 82 and 85 on both ends of the developing roll 45 are brought into contact with the non-image forming areas on both ends of the photosensitive drum 27, and a gap G 3 between the surface of the developing roll 45 and the surface of the photosensitive drum 27 is formed. Maintained with high accuracy.

  In addition, the gap G1 between the tip of the above-described cutting blade 60 and the surface of the magnetic roll 44 is also maintained with high accuracy. That is, the ear cutting blade 60 is positioned with respect to the developing container 41. Similarly, the magnetic roll 44 is also positioned with respect to the developing container 41 through bearing members 73 and 74. That is, since both are positioned with respect to the developing container 41, the gap G1 can be held with high accuracy.

  According to the present invention, the magnetic roll 44 and the developing roll 45 are held by the pair of bearing members 73 and 74 before being incorporated into the developing container 41, and the inter-roller gap G2 is measured in this state to obtain a desired inter-roller gap. After determining the combination of rollers that satisfy G2, the bearing members 73 and 74 can be attached to the developing container 41 as they are, so that the inter-roller gap G2 can be held with high accuracy. Further, as described above, the bearing members 73 and 74 are attached to the developing container 41 with the bearing boss portions 80 and 83 on the bearing member 73 and 74 side in the bearing supporting hole 77 and the bearing support notch hole 78 on the developing container 41 side. The magnetic roll 44 and the developing roll 45 can be attached to the developing container 41 by a very simple operation of engaging and lowering the developing roll 45 side of the bearing members 73 and 74 downward after the engagement.

  As described above, according to the present embodiment, the measurement of the gap G2 between the rollers of the magnetic roll 44 and the developing roll 45 and the recombination of the rollers are simple. It is possible to ensure with high accuracy the gap G1 between the front end portion of the spike cutting blade 60 and the gap G3 between the surface of the developing roll 45 and the surface of the photosensitive drum 27.

  In the above description, the case where the present invention is applied to an electrophotographic tandem four-color full-color printer has been described as an example. However, the present invention is not limited to this, for example, an intermediate transfer belt is used. The present invention can also be applied to an intermediate transfer type color image forming apparatus, and in this case, substantially the same effect can be obtained.

  The present invention can be widely applied in general when it is necessary to maintain a gap between two rollers disposed adjacent to each other with high accuracy.

2 is a diagram schematically illustrating an internal configuration of the image forming apparatus as viewed from the left side. FIG. It is a figure which shows typically the structure inside the developing device seen from the left side. (A) is a perspective view of the developing device showing a state in which the rear side wall located on the photosensitive drum side in the developing container is removed, and (b) is a state in which the positional relationship when being incorporated in the developing container is maintained. It is a perspective view which shows the removed magnetic roll and image development roll. It is a perspective view explaining the bearing support hole with which one bearing member is engaged. It is a perspective view explaining the bearing support notch hole with which the other bearing member is engaged. (A) is a perspective view explaining the state by which one bearing member was engaged with the bearing support hole. (B) is a perspective view explaining one bearing member engaged with a bearing support hole. (A) is a perspective view explaining the other bearing member engaged with a bearing support notch hole. (B) is a perspective view explaining the way in the middle of engaging the other bearing member with a bearing support notch hole. FIG. 6 is a perspective view for explaining a state in which the other bearing member is engaged with the bearing support notch hole and then rotated so as not to come off.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Image forming apparatus main body, 3 ... Sheet feeding part, 4 ... Image forming part, 5 ... Fixing part, 6 ... Sheet discharge part, 27 ... Photosensitive drum (Image (Supporting member), 31... Developing device, 33... Transfer device, 41 .. developing container, 44 .. magnetic roll, 45 .. developing roll, 53 .. stirring mixer storage chamber (developer stirring chamber), 54. ... paddle mixer storage chamber (developer stirring chamber), 55 ... magnetic roll storage chamber, 56 ... development roll storage chamber, 60 ... ear cutting blade (layer thickness regulating member), 73 ... bearing member (one bearing) Member), 74... Bearing member (the other bearing member), 75, 76... Boss support portion, 77... Bearing support hole, 78 ....... bearing support notch hole (bearing support portion), 78 b. 80, 83 ... bearing boss, 82, 85 ... gap pulley (spacer), 3a ...... cut-out portion,

Claims (9)

A developer agitating chamber for accommodating and agitating a two-component developer having a toner and a carrier; a magnetic roll for carrying and conveying the developer supplied from the developer agitating chamber; and a surface of the magnetic roll A developing roll that carries the toner supplied from the developer on the surface, conveys the toner, and adheres to the electrostatic latent image on the image carrier,
A developer container having the developer stirring chamber, a magnetic roll storage chamber for storing the magnetic roll, and a development roll storage chamber for storing the development roll;
A pair of one bearing member that supports one end of the magnetic roll and the developing roll at a predetermined pitch and the other bearing member that supports the other end of the magnetic roll and the developing roll at the predetermined pitch. A bearing member,
The magnetic roll and the developing roll are attached to the developing container by mounting the pair of bearing members in a state of holding the magnetic roll and the developing roll at predetermined positions of the developing container.
A developing device. The developer container is provided with the developer stirring chamber, the magnetic roll storage chamber, and the development roll storage chamber in order from the top.
The developing device according to claim 1. The pair of bearing members each have a cylindrical bearing boss portion coaxial with the magnetic roll,
The developer container has a boss support portion formed with a pair of bearing support holes that rotatably support the bearing boss portion.
The developing device according to claim 1, wherein At least one of the boss support portions has an opening that enables engagement and disengagement of the boss portion with respect to the bearing support hole from a direction orthogonal to a central axis of the bearing support hole.
The developing device according to claim 3. The opening is formed with a width dimension shorter than the diameter of the bearing support hole,
The bearing boss has a notch formed in a part thereof with a width dimension shorter than a width dimension of the opening.
The developing device according to claim 4. The direction of the opening is determined by lowering the developing roll side of the bearing member downward after passing the notch through the opening and engaging the bearing boss with the bearing support hole. The orientation is set so that the member can be placed at the mounting position.
The developing device according to claim 5. In the magnetic roll storage chamber of the developing container, a layer thickness regulating member having a tip portion facing the surface of the magnetic roll via a minute gap is disposed.
The developing device according to claim 1, wherein An annular spacer that holds the gap between the surface of the developing roll and the surface of the image carrier in a predetermined dimension by being abutted against the surface of the image carrier is attached to the developing roll.
The developing device according to claim 1, wherein An image carrier on which an electrostatic latent image is formed, a developing device that develops the electrostatic latent image with toner, and a transfer device that transfers a toner image formed on the surface of the image carrier to a sheet. In the provided image forming apparatus,
The developing device is the developing device according to any one of claims 1 to 8.
An image forming apparatus.

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