JP4071679B2 - Grounding structure and image forming apparatus provided with the structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a grounding structure for a rotating shaft that is rotatably supported around a shaft center on a predetermined frame, and an image forming apparatus including the structure.
[0002]
[Prior art]
  Conventionally, a grounding structure 900 as shown in FIG. 8 described in Patent Document 1 is known for grounding of a rotating shaft provided in a paper conveyance system of an image forming apparatus. This grounding structure 900 is a plate in which the insertion hole 903 is fitted over the end portion of the rotation shaft 907 for paper conveyance that is penetrated and supported by a predetermined plate-like frame 909 in the apparatus via a bearing member 908. A conductive plate 901 and a conductive bracket 902 made of an elastic material (specifically, a metal leaf spring) to which the lower end of the conductive plate 901 is electrically connected. The conduction bracket 902 is integrally fixed to the plate frame 909 by screwing or welding.
[0003]
  A synthetic resin roller 906 for conveying the paper is concentrically fitted and fixed to the rotary shaft 907, and static electricity is generated in the roller 906 due to frictional contact with the paper during the conveyance of the paper by the rotation of the roller 906. Since the static electricity is grounded through the ground structure 900, it is possible to avoid adverse effects on image formation.
[0004]
  A connecting projection 904 narrower than the main body of the conducting plate 901 projects downward from the lower portion of the conducting plate 901, and is inserted into a portion corresponding to the connecting projection 904 of the conducting bracket 902. A hole 905 is formed, and the connection protrusion piece 904 is inserted into the fitting insertion hole 905 so that the two are electrically connected.
[0005]
  Then, the static electricity charged in the roller 906 is transferred to the plate through the rotation shaft 907, the connection projection 904 of the conduction plate 901, and the conduction bracket 902 provided with the fitting insertion hole 905 in which the connection projection piece 904 contacts the edge. Is guided to the frame 909 and grounded via the plate frame 909.
[0006]
  In addition, since the connection protrusion 904 of the conduction plate 901 is inserted into the fitting insertion hole 905 of the conduction bracket 902, the displacement of the conduction plate 901 is absorbed by the elastic deflection of the conduction bracket 902, and the Good conductivity can be ensured.
[0007]
[Patent Document 1]
      JP 2003-12180 A
[0008]
[Problems to be solved by the invention]
  By the way, in the grounding structure 900 as described in Patent Document 1, the rotation shaft 907 is fitted into the insertion hole 903 of the conduction plate 901, and the outer peripheral surface of the rotation shaft 907 and the inner periphery of the insertion hole 903 are thereby formed. Since energization between the two is ensured by contact with the surface, high accuracy is required for the diameter of the insertion hole 903, and if the diameter of the rotating shaft 907 is different, A dedicated conductive plate 901 has to be prepared separately, and there is a problem that it lacks versatility.
[0009]
  Further, since the conduction bracket 902 is formed of a metal leaf spring, when the conduction bracket 902 is connected to the conduction plate 901 in a bent state, the elastic force of the conduction bracket 902 is conducted. It is transmitted to the rotating shaft 907 via the plate 901, and the concentric roller 906 that is concentric with the rotating shaft 907 is slightly eccentric. This eccentricity affects the paper conveyance force by the roller 906, and there is a problem that an accurate image cannot be transferred to the paper due to fluctuations in the paper conveyance state by the roller 906.
[0010]
  Furthermore, although not limited to the grounding structure 900 of Patent Document 1, such a grounding structure is usually employed independently of each other in a member that is likely to generate static electricity, so that the number of parts increases and the parts are increased. There is an inconvenience that not only leads to an increase in cost and assembly cost, but also an obstacle to downsizing of the apparatus.
[0011]
  The present invention has been made to solve the above-described problems, and does not require a high degree of machining accuracy. This contributes to a reduction in machining cost, and each size shaft. A grounding structure that does not adversely affect image formation and does not hinder downsizing of the apparatus, and an image forming apparatus including the structure are provided. It is intended to provide.
[0012]
[Means for Solving the Problems]
  The invention according to claim 1 is a grounding structure for electrically grounding a rotating shaft pivotally supported on a synthetic resin frame through a bearing member so as to be rotatable around an axis center, the rotating shaft A conductive portion that is externally fitted to the conductive member, and a grounding portion that is electrically connected to the conductive portion that is connected to a predetermined grounding position. The conductive portion includes an internal fitting hole into which the bearing member is fitted, and the internal fitting. One or a plurality of pressure contact protrusions protruding from the inner peripheral surface of the hole toward the hole center direction and having a tip pressed against the bearing memberIn addition, an interposition part capable of plastic deformation having conductivity is provided between the conduction part and the grounding part.It is characterized by that.
[0013]
  According to the present invention, static electricity generated by an easily-chargeable member (for example, a rubber roller body) mounted on or in contact with the rotating shaft flows to the grounding position via the rotating shaft, the bearing member, the pressure contact protrusion, and the grounding portion. As a result, the static electricity of the easily chargeable member is removed.
[0014]
  Further, since the conducting portion can be applied to the rotating shafts having different diameters within the range of the elastic deformation of the pressure contact protrusion, it is not necessary to provide a dedicated conducting portion for each rotating shaft having different diameters. The conduction part according to the above is highly versatile.
[0015]
  If the pressure contact protrusions are provided at equal pitches in the circumferential direction, the rotation shaft is uniformly pressed and supported by the tip of the pressure contact protrusion, so a reliable electrical connection between the conducting portion and the rotation shaft is ensured. While ensuring the state, the elastic force of the pressure contact protrusion is evenly applied to the rotating shaft in the circumferential direction, thereby reliably preventing the inconvenience that the rotating shaft is eccentric.
[0016]
  furtherIn addition, between the conducting portion and the grounding portion, there is provided an interposed portion capable of plastic deformation having conductivity.The
[0017]
  ThereforeEven if a dimensional error occurs due to a design error or an assembly error in the distance between the conducting part mounted on the rotating shaft and the grounding part fixed to the grounding position, plastic deformation interposed between them is possible. In addition to being able to easily cope with the plastic deformation of the interposed portion, the elastic deformation does not occur in the interposed portion due to the plastic deformation, and therefore the rotating shaft is pressed in one direction by the elastic force and the center Inconveniences such as going crazy are surely prevented.
[0018]
  Claim2The described invention is claimed.1In the invention described above, the grounding portion has a connection portion connected to the frame.
[0019]
  According to the present invention, since the connection portion is connected to the frame body, static electricity generated in the frame body can be eliminated through the connection portion, and it is necessary to employ a grounding structure dedicated to the frame body. This contributes to a reduction in the number of parts and to a reduction in the size of the device to which the grounding structure is applied.
[0020]
  Claim3The invention described is claimedItem 2In the described invention, an urging structure for pressing the connecting portion against the frame is provided.
[0021]
  According to this invention, since the connection portion is pressed against the frame body by the urging force of the urging structure, it is possible to ensure a reliable electrical connection between the connection portion and the frame body.
[0022]
  Claim4The invention described in claims 1 to3In any one of the inventions, the bearing member is made of a conductive resin material.
[0023]
  According to this invention, the conductive resin material is suitable as a material for a bearing member for grounding because it is lightweight, has good mass productivity, and can be mass-produced at low cost. The generated static electricity is grounded through a bearing member made of a conductive resin material.
[0024]
  Claim5The described invention is claimed.4In the described invention, the conductive resin material contains a lubricant.
[0025]
  According to this invention, the conductive resin material can suitably contain a lubricant. The rotating shaft rotates smoothly due to the lubricating performance of the contained lubricant.
[0026]
  Claim6The described invention is claimed.2In the described invention, the conducting portion, the ground portion, the interposed portion, and the connecting portion are formed by processing a single metal plate.
[0027]
  According to this invention, since the grounding structure is finished by processing one metal plate, it becomes possible to reduce the number of parts to the limit as compared with the case where the grounding structure is manufactured by combining a plurality of members. Contributes to reduction of parts cost and assembly cost. Examples of the processing of the metal plate include punching and bending processes using a press machine.
[0028]
  Claim7The invention described in the above is an image forming apparatus configured to form a toner image on the peripheral surface of the photosensitive drum by toner supplied from the developing device, and to transfer the toner image onto a sheet.6The grounding structure according to any one of the above is employed.
[0029]
  According to the present invention, it is possible to effectively perform static elimination of a portion where static electricity easily occurs including various rotating shafts in the image forming apparatus, and it is possible to eliminate a transfer processing defect caused by static electricity. .
[0030]
  Claim8The described invention is claimed.7In the described invention, the rotating shaft is used for a paper transport roller.
[0031]
  According to the present invention, the transport roller is a component that is easily charged with static electricity due to friction with the transported paper, but by using the grounding structure, the static electricity stored in the transport roller is reliably eliminated.
[0032]
  Claim9In the invention described in claim 8, in the invention described in claim 8, the rotating shaft is for one roller of a pair of paper conveying rollers, and the roller is made of a metal material, while the other roller has a shaft. The roller body to be removed is made of an elastomer, and static electricity charged on the roller body of the other roller is neutralized through the one roller.
[0033]
  In the present invention, an elastomer is a high-molecular substance that exhibits remarkable elasticity near room temperature, and is used as a conceptual term that includes these foams as well as rubber and soft synthetic resins.
[0034]
  According to the present invention, the static electricity generated in the roller body made of elastomer due to contact with the paper being conveyed is grounded via the roller made of metal material in contact with the roller body.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
  FIG. 1 is a side sectional view showing an outline of an embodiment of an image forming apparatus to which a grounding structure according to the present invention is applied. As shown in FIG. 1, the image forming apparatus 10 includes an image forming unit 11 that plays a central role, a transfer belt unit 12 disposed below the image forming unit 11, and the transfer belt unit 12 mounted thereon. A sheet storage unit 14 for storing sheets to be fed between the image forming unit 11 and the transfer belt unit 12 through the sheet supply unit 13, and the image forming unit 11 and the transfer belt. The fixing device 15 disposed on the downstream side (left side in FIG. 1) of the unit 12 is formed by being housed in a box-shaped device main body 16 having a rectangular parallelepiped shape in appearance.
[0036]
  The image forming unit 11 performs a toner image transfer process on the paper supplied from the paper storage unit 14 via the paper supply unit 13, and in the present embodiment, on the upstream side (the right side in FIG. 1). ), A yellow unit 11Y, a magenta unit 11M, a cyan unit 11C, and a black unit 11K which are sequentially arranged from the downstream side to the downstream side. Each unit 11Y, 11M, 11C, and 11K is positioned and mounted in a predetermined relative positional relationship with respect to the device main body 16 and each unit.
[0037]
  Each unit 11Y, 11M, 11C, 11K is provided with a developing device 111 and a photosensitive drum 112, respectively. Each photoconductor drum 112 is supplied with toner from a corresponding developing device 111 and is rotated clockwise in FIG.
[0038]
  A charging unit 114 is provided at a position on the upper left side in FIG. 1 of each photosensitive drum 112, and an exposure unit 113 is provided at a position on the upper right side in FIG. Each photosensitive drum 112 is charged uniformly by the charging unit 114, and LED light based on image data input from a reading device (not shown) is charged from each exposure unit 113. By irradiating the peripheral surface of the drum 112, an electrostatic latent image is formed on the peripheral surface of each photosensitive drum 112. By supplying toner from the toner container of the developing device 111 to the electrostatic latent image, a toner image is formed on the peripheral surface of the photosensitive drum 112.
[0039]
  The transfer belt unit 12 is provided at a position below the image forming unit 11 so as to correspond to each photosensitive drum 112. The transfer belt unit 12 includes a base 121 mounted on the paper feeding unit 13 and a transfer belt 122 supported by the base 121 and rotating in the counterclockwise direction in FIG. The transfer belt 122 includes a drive roller 133 provided at the right end of the base 121 in FIG. 1, a driven roller 134 provided at the right end, and a slight upper position between the drive roller 133 and the driven roller 134. It is wound around a plurality of transfer rollers 135 arranged at a pitch, and circulates by the rotational drive of the drive roller 133.
[0040]
  Each of the transfer rollers 135 is pressed against the corresponding photosensitive drum 112 via the transfer belt 122 so that the transfer from the photosensitive drum 112 to the sheet conveyed by the transfer belt 122 is reliably performed. It has become. Further, a cleaning mechanism 115 for removing residual toner on the circumferential surface of the photosensitive drum 112 and cleaning the photosensitive drum 112 is provided at a lower right position in FIG. 1 of each photosensitive drum 112. The peripheral surface of the photosensitive drum 112 cleaned by the cleaning mechanism 115 is directed to the charging unit 114 for a new charging process.
[0041]
  The sheet feeding unit 13 picks up one sheet at a time from a bundle of sheets loaded in the sheet storage unit 14 and feeds them between the photosensitive drum 112 and the transfer belt 122. In the present invention, the transfer belt unit 12 is inserted into and removed from the device main body 16 integrally. The sheet feeding unit 13 is disposed at a position facing a predetermined pair of conveying rollers 131 for conveying the uppermost sheet picked up from the sheet bundle in the sheet storage unit 14 and the transfer belt 122 and the photosensitive drum 112. In addition, a registration roller pair 132 and the like for feeding the paper after positioning the paper are provided.
[0042]
  Then, the paper picked up from the paper storage unit 14 is supplied onto the transfer belt 122 via the conveying roller pair 131 and the registration roller pair 132, and the image forming unit 11 and the transfer belt unit are rotated along the circumference of the transfer belt 122. 12 and the toner images on the photosensitive drums 112 of the image forming units 11Y, 11M, 11C, and 11K are sequentially transferred onto the paper during the passage.
[0043]
  Next, the sheet on which the toner image has been transferred is introduced into a fixing device 15 having a fixing roller pair 151, and the toner is fixed on the sheet by a heat fixing process by passing between the heated fixing roller pair 151. A color image is formed. The sheet with the color image on which the fixing process has been completed is discharged to a discharge unit 161 formed on the top of the apparatus main body 16 through a predetermined conveyance path.
[0044]
  In the image forming apparatus 10, the grounding structure according to the present embodiment is used to neutralize static electricity generated in the rotating shafts provided at various places and a predetermined frame that supports the rotating shaft. FIG. 2 is a perspective view showing an embodiment of the frame 20, and FIG. 3 is a perspective view showing a right part thereof. 4 is a partially enlarged perspective view taken along line A in FIG. 2 to 4, the XX direction is referred to as the width direction, and the YY direction is referred to as the front-rear direction. In particular, the −X direction is referred to as the left, the + X direction as the right, the −Y direction as the front, and the + Y direction as the rear.
[0045]
  In the upper part of the upstream side (right side in FIG. 1) of the paper feeding unit 13 (FIG. 1), a paper for feeding the paper drawn from the paper storage unit 14 via the conveying roller pair 131 to the image forming unit 11. A transport unit 200 (FIG. 3) is provided. The sheet conveying unit 200 is interposed between the frame body 20, the registration roller pair 132 mounted on the frame body 20, and an upper roller shaft (rotary shaft) 31 described later of the registration roller pair 132. And a grounding structure 50.
[0046]
  As shown in FIGS. 2 and 3, the frame 20 is constructed between a pair of side plates 21 in the width direction (only the right side plate is shown in FIG. 3) and the pair of side plates 21. It has a basic configuration including a guide portion 25 for guiding paper. The side plate 21 includes a side plate main body 22, a roller support portion 23 formed at a front position of the side plate main body 22, a substantially intermediate position in the vertical direction of the side plate main body 22, and a position behind the roller support portion 23. And a shelf 24 projecting in the opposite direction. The shelf 24 is a place where the grounding structure 50 according to the present invention is attached.
[0047]
  The guide portion 25 includes an erection plate 26 installed vertically between the shelf portions 24 of the side plate 21 and a plurality of guide fins 27 protruding rearward from the erection plate 26. Each guide fin 27 is formed in an arc shape, and the sheet is supplied to the registration roller pair 132 along the arc-shaped ridge line. Ribs 28 are installed between the adjacent guide fins 27, and the presence of these ribs 28 makes the guide portion 25 strong in strength.
[0048]
  The registration roller pair 132 includes an upper roller 30 and a lower roller 40 disposed opposite to the upper roller 30 at a position below the upper roller 30. As shown in FIG. 4, the upper roller 30 includes an upper roller shaft 31 provided between the roller support portions 23 of the pair of side plates 21, and an upper roller body 32 concentrically integrated with the upper roller shaft 31. It is prepared for.
[0049]
  The upper roller shaft 31 has its end portion fitted into a concentric bearing member 33 in a sliding contact state, and the bearing member 33 cuts downward from the top to the opposing surfaces of the pair of roller support portions 23. By being fitted into a rarely formed shaft support groove 231 from above, it is mounted between the pair of roller support portions 23 via each bearing member 33. The upper roller shaft 31 is made of a metal material, and the upper roller body 32 is also made of the same metal material. Accordingly, static electricity generated in the lower roller body 42 made of rubber due to the conveyance of the sheet passes through the upper roller body 32, the upper roller shaft 31, the bearing member 33, and the grounding structure 50 that are in contact with the lower roller body 42. It will be grounded. Incidentally, if the rubber material which comprises the lower roller main body 42 has electroconductivity, it will earth more effectively.
[0050]
  The bearing member 33 is provided with a pair of flat surfaces 331 that extend in the direction of the hole center on opposite surfaces of the outer peripheral surface. The distance between the flat surfaces 331 is set slightly shorter than the groove width of the shaft support groove 231 of the roller support portion 23. Therefore, the bearing member 33 is attached to the shaft support groove 231 in a non-rotating state by being fitted into the shaft support groove 231 while sliding the pair of flat surfaces 331 in sliding contact with the groove wall of the shaft support groove 231. The bearing member 33 has a flange 332 formed at the end on the upper roller body 32 side, and the flange 332 is brought into contact with the end surface of the upper roller body 32 to thereby move the upper roller body 32 in the axial direction. Misalignment is reliably prevented.
[0051]
  The bearing member 33 is formed of a conductive resin material in the present embodiment. As the conductive resin material, for example, a material in which a conductive material such as carbon black is kneaded with PPS (polyphenylene sulfide) is preferably used. Such a conductive resin material is suitable as a material for a bearing member for grounding because it is lightweight, has good mass productivity, and can be mass-produced at low cost. Then, by allowing the conductive resin material to contain a lubricant, the upper roller shaft 31 can smoothly rotate with the lubricating performance of the contained lubricant.
[0052]
  The present invention is not limited to the bearing member 33 made of a conductive resin material, and may be formed of a copper-based sintered material. The copper-based sintered material is suitable as a material for the bearing member 33 because it is lightweight, has good workability, and has excellent conductivity. Moreover, since the sintered material is in a so-called porous state in which countless fine maximums are formed, it can be suitably impregnated with a lubricant. Since the bearing member 33 is impregnated with the lubricant, the lubricant impregnated in the bearing member 33 oozes between the inner peripheral surface of the bearing member 33 and the outer peripheral surface of the upper roller shaft 31. The upper roller shaft 31 can rotate smoothly due to the lubricating performance of the oozed lubricant.
[0053]
  The lower roller 40 includes a lower roller shaft 41 provided between the bearing support portions 44 in parallel with the upper roller shaft 31 at a position below the upper roller 30, and a lower portion concentrically fitted to the lower roller shaft 41. A roller main body 42 is provided. One end of the lower roller shaft 41 protrudes outward from a shaft support hole 232 formed at a position below the shaft support groove 231 of the roller support portion 23 of the side plate 21, and the upper roller on the outside of the roller support portion 23. The shaft 31 is gear-connected. Further, the upper roller shaft 31 is spring-biased to the lower roller shaft 41 side outside the roller support portion 23 via a bearing (not shown).
[0054]
  Unlike the upper roller main body 32, the lower roller main body 42 is made of a rubber material, and can reliably convey a sheet with a large frictional resistance. Further, in a state where the lower roller shaft 41 is installed between the pair of bearing support portions 44, the pressing contact position between the peripheral surface of the lower roller shaft 41 and the peripheral surface of the upper roller main body 32 faces the upper position of the transfer belt 122. Is set. Accordingly, the sheet from the conveying roller pair 131 (FIG. 1) sandwiched between the upper and lower roller bodies 32 and 42 is surely sent out toward the image forming unit 11 by the driving rotation of the upper roller 30.
[0055]
  FIG. 5 is a perspective view showing an embodiment of the grounding structure according to the present invention, and shows a state where it is mounted on the bearing member 33 (in a direction corresponding to FIGS. 2 and 3). Yes.) The grounding structure 50 according to the present embodiment is configured such that the static electricity generated by the friction between the upper and lower roller bodies 32 and 42 due to the paper conveyance rotation operation in the state where the paper is sandwiched and the paper in the frame 20. Is for removing static electricity generated by sliding contact with the guide fins 27 and the like.
[0056]
  Such a grounding structure 50 is formed by bending a single metal plate that has been punched into a predetermined shape using a predetermined press machine, and is externally fitted to the bearing member 33 as shown in FIG. The basic structure provided with the conduction | electrical_connection part 51, the earthing | grounding part 53 integrally formed in this conduction | electrical_connection part 51 via the strip | belt-shaped insertion part 52, and the connection part 54 attached to this grounding part 53 integrally. have.
[0057]
  The conduction portion 51 circulates the static electricity charged in the upper roller body 32 toward the grounding portion 53 via the upper roller shaft 31 and the bearing member 33, and is an insertion hole (internal fitting hole) into which the bearing member 33 is inserted. ) 511 and a pressure contact protrusion 513 whose tip protrudes slightly radially from the inner peripheral surface of the insertion hole 511 toward the hole center.
[0058]
  In the present embodiment, the insertion hole 511 has a pair of linear chord edges 512 (one of which is shown in FIG. 5) in a symmetrical position so as to correspond to the cross-sectional shape of the portion where the flat surface 331 of the bearing member 33 is formed. Only the chord edge portion 512 is shown.) Is formed in an oval shape so that the conducting portion 51 can be mounted on the bearing member 33 in a positioned state.
[0059]
  The press contact protrusion 513 is for ensuring a reliable electrical connection state between the grounding portion 53 and the conducting portion 51. In this embodiment, the press contact protrusion 513 is 90 ° out of phase with the string edge portion 512. A pair is provided at positions opposite to each other. The press-contact projection 513 is projected from the groove bottom of the cut groove 515 formed by cutting outward from the inner peripheral surface of the insertion hole 511 in the radial direction, and sharply sharpens at the tip. An apex end 514 formed in this manner is provided.
[0060]
  The tip of the apex end 514 protrudes slightly in the hole center direction from the inner peripheral surface of the insertion hole 511. Therefore, by inserting the bearing member 33 into the insertion hole 511, the press contact protrusion 513 is elastically deformed in an arc shape toward the outer side in the radial direction, and the elastic force generated thereby causes the press contact protrusion 513 and the bearing member 33 to be deformed. A reliable electrical connection state can be secured.
[0061]
  The interposition part 52 protrudes from the lower end part of the outer peripheral edge part of the conducting part 51 in FIG. The belt-like interposed portion 52 is dimensioned slightly longer than the normal distance between the conducting portion 51 and the grounding portion 53, and even if an error occurs between the installation positions of the conducting portion 51 and the grounding portion 53, It can be easily accommodated by adjusting the amount of deflection of the installation portion 52.
[0062]
  The grounding portion 53 is fixed to a later-described roller support block 29 (FIG. 6) supported on the upper surface of the shelf portion 24 (FIG. 3) of the frame body 20. They are integrally coupled in a state of being orthogonal to the conductive portion 51 and extending rearward. A square hole 531 is formed in the center of the ground contact portion 53, and circular holes 532 are formed in front and rear positions sandwiching the square hole 531. Further, the rear end portion of the grounding portion 53 is bent downward toward the rear side, and a bifurcated detent protrusion piece 533 that stops so as not to be displaced by sandwiching a covering portion of the ground wire (not shown) at the upper portion. Projected toward.
[0063]
  Further, the grounding portion 53 is provided with a locking projection 534 having an inverted L-shape projecting upward from the rear edge portion of the square hole 531 and having its upper end portion folded back rearward. Is provided. The locking protrusions 534 are for locking the grounding structure 50 to the roller support block 29 in advance so that the grounding structure 50 can be easily mounted on the shelf 24. .
[0064]
  The connecting portion 54 is for removing static electricity stored in the frame body 20 when the sheet is in sliding contact with the guide fins 27 (FIGS. 2 and 3), and the rear end of the interposed portion 52 in FIG. Is formed by being bent downward from the front end edge of the ground contact portion 53 on the right side of the contact portion 53. The connecting portion 54 includes a flat connecting portion main body 541 and a bent piece 542 bent forward from a lower end portion of the connecting portion main body 541. The connecting portion main body 541 is electrically connected to a roller support block 29 whose front side is integrally fixed to the frame body 20.
[0065]
  Here, first, the roller support block 29 will be described in detail with reference to FIGS. 2 and 3 as needed based on FIGS. 6 and 7. FIG. 6 is a perspective view showing the positional relationship between the roller support block 29 and the grounding structure 50, and FIG. 7 is a cross-sectional view in side view with the roller support block 29 attached to the frame 20. .
[0066]
  First, as shown in FIG. 6, the roller support block 29 includes a support block main body 291 disposed in contact with the inner surface of the roller support portion 23 of the frame body 20, and a rear surface of the support block main body 291 from the rear to the rear. And a grounding portion sandwiching plate 297 projecting therefrom.
[0067]
  The support block main body 291 includes a front plate 292 that extends in the vertical direction, a rear plate 293 that is disposed opposite to the front plate 292 in the rear, and a bridge plate 294 that is bridged between the front and rear plates 292 and 293. It is prepared for.
[0068]
  The bridging plate 294 is provided with an insertion recess 2941 for fitting the bearing member 33, which is formed by cutting out from the upper edge portion, and a lower roller below the 2941. An insertion hole 2492 for inserting the 40 lower roller shafts 41 (FIG. 4) is formed. Further, a cylindrical portion 296 extending in the front-rear direction in a state where the front and rear plates 292 and 293 have openings is formed at a position below the insertion hole 2492 in the bridge plate 294. A cylindrical body 61 to be described later is fitted into the cylindrical portion 296.
[0069]
  The grounding portion sandwiching plate 297 is disposed in a state where the grounding portion 53 is sandwiched on the upper surface of the shelf portion 24 of the frame body 20, and a corner of the same size is provided at a position corresponding to the square hole 531 of the grounding portion 53. Holes 298 are formed, and circular holes 299 of the same size are formed at positions corresponding to the pair of circular holes 532 of the ground contact portion 53.
[0070]
  On the other hand, as shown in FIG. 7, a pair of positioning projections 241 in the front-rear direction are provided projecting upward at positions opposed to the circular holes 299 on the upper surface of the shelf 24. Further, a screw hole 242 screwed downward is screwed at a position corresponding to the square hole 531 on the upper surface of the shelf 24. Then, by fitting each circular hole 532 to each positioning projection 241, the grounding portion 53 is positioned on the shelf portion 24, and the grounding portion sandwiching plate 297 is overlapped with the positioned grounding portion 53 so that each circular hole 299 is overlapped. Are inserted into the pair of positioning protrusions 241, and a screw (not shown) having the ground wire entangled in the square holes 298 and 531 is inserted, and the screw is screwed and fastened to the screw hole 242. Thus, the grounding portion 53 is electrically grounded via the grounding member.
[0071]
  Then, in a state where the grounding portion 53 is sandwiched between the shelf portion 24 and the grounding portion sandwiching plate 297, the connection portion main body 541 is connected to the rear plate 293 of the roller support block 29 and the front portion of the shelf portion 24 as shown in FIG. The static electricity stored between the plates 243 and stored in the frame body 20 is grounded (grounded) via the shelf 24 and the connecting portion main body 541.
[0072]
  In the present embodiment, a pressure contact structure (biasing structure) 60 is employed in order to ensure a contact state of the connection portion main body 541 with respect to the shelf portion 24 (the front plate 243 thereof). The pressure contact structure 60 includes a columnar body 61 that is fitted into the cylindrical portion 296 of the roller support block 29 in a slidable contact state, and a coil spring 65 that is mounted at a rear position of the cylindrical body 61 within the cylindrical portion 296. It is prepared for.
[0073]
  The cylindrical body 61 has a central cylindrical body 62 whose outer diameter is set slightly smaller than the inner diameter of the cylindrical portion 296, and a central cylinder that is concentrically projected forward from the front surface of the central cylindrical body 62. The front cylindrical body 63 having a smaller diameter than the body 62 and the rear cylindrical body 64 having a smaller diameter than the central cylindrical body 62 projecting concentrically from the rear surface of the central cylindrical body 62. The front cylindrical body 63 has a front end portion that is tapered forward.
[0074]
  On the other hand, a through hole 2961 concentric with the cylindrical portion 296 is formed in the front plate 292 of the support block main body 291. The through hole 2961 is set to have a diameter that allows the front cylindrical body 63 to pass through in a sliding contact state. The rear plate 293 of the support block main body 291 is provided with a circular opening 2962 having the same inner diameter as that of the cylindrical portion 296.
[0075]
  Then, the cylindrical body 61 is fitted and inserted into the cylindrical portion 296 from the front cylindrical body 63 side through the circular opening 2962, and the coil spring 65 is continuously press-fitted into the cylindrical portion 296 in a state where the coil spring 65 is externally fitted to the rear cylindrical body 64. Then, the connecting portion main body 541 is sandwiched between the rear plate 293 and the front plate 243 of the shelf portion 24, so that the connecting portion main body 541 is moved by the biasing force of the coil spring 65 as shown in FIG. By pressing toward the front plate 243, a reliable electrical connection is ensured between the connection portion main body 541 and the front plate 243 of the shelf portion 24.
[0076]
  Incidentally, the pressing force of the coil spring 65 against the shelf 24 (the front plate 243) of the connecting portion main body 541 is set to 100 g / cm 2 to 500 g / cm 2. This range is set because if the pressure is less than 100 g / cm 2, it is difficult to obtain a reliable electrical connection state between the connecting portion main body 541 and the front plate 243 because the pressing force is too small. This is because even if the pressing force does not exceed 500 g / cm 2, a reliable electrical connection state can be secured between the two.
[0077]
  As described in detail above, the grounding structure of the present embodiment includes an upper part that is provided with a member (upper roller main body 32) that can be easily charged with static electricity, and is supported on a predetermined frame 20 so as to be rotatable about an axis. The roller shaft 31 is electrically grounded, and a conductive portion 51 that is externally fitted to a cylindrical bearing member 33 that is conductive and supports the upper roller shaft 31 is formed integrally with the conductive portion 51. And a conductive grounding portion 53 attached to a predetermined grounding position (the shelf portion 24 of the frame body 20). The conductive portion 51 includes an insertion hole 511 into which the upper roller shaft 31 is fitted, The upper roller shaft 31 has a plurality of pressing protrusions 513 that protrude from the inner peripheral surface of the insertion hole 511 toward the hole center direction at an equal pitch in the circumferential direction. Easy-to-charge member (upper The static electricity generated in the main body 32) flows to the grounding position via the upper roller body 32, the upper roller shaft 31, the bearing member 33, the pressure contact projection 513, and the grounding portion 53. Static electricity generated by contact can be reliably removed.
[0078]
  The bearing member 33 fitted in the insertion hole 511 of the conduction portion 51 is uniformly pressed and supported by the tip portions of a plurality of press-contact projections 513 protruding at an equal pitch in the circumferential direction from the inner peripheral surface of the insertion hole 511. Therefore, after securing a reliable electrical connection state between the conducting portion 51 and the bearing member 33, the elastic force of the press-contact projection 513 is evenly applied to the bearing member 33 in the circumferential direction. Inconvenience that the upper roller shaft 31 is eccentric can be reliably prevented.
[0079]
  Further, since the same conducting portion 51 can be applied to the upper roller shaft 31 having a different diameter within the range of the elastic deformation of the pressure contact projection 513, a dedicated grounding is provided for each upper roller shaft 31 having a different diameter. It is not necessary to provide the structure 50, and the grounding structure 50 can be made versatile.
[0080]
  In addition, since the conductive portion 51 and the grounding portion 53 are provided with an interposed portion 52 that is conductive and capable of plastic deformation, the conductive portion 51 mounted on the upper roller shaft 31 and the grounding portion are grounded. Even if a dimensional error occurs due to a design error or assembly error in the distance from the grounding portion 53 fixed at a position, it can be easily handled by plastic deformation of the interposed portion 52 that can be plastically deformed between the two. In addition to being able to be plastically deformed, there is no elastic force generated in the interposition part 52, and therefore the inconvenience that the upper roller shaft 31 is pressed in one direction by the elastic force and is upset is effective. Can be prevented.
[0081]
  Further, since the connection portion 54 connected to the frame body 20 is integrally provided in the grounding portion 53, the connection portion 54 is generated in the frame body 20 by electrically connecting the connection portion 54 to the frame body 20. Static electricity can also be removed through this connection portion 54. Therefore, it is not necessary to separately adopt a grounding structure dedicated to the frame body 20, thereby contributing to the reduction in the number of parts and contributing to the downsizing of the device to which the grounding structure is applied.
[0082]
  Further, since the bearing member 33 is formed of a conductive resin material, the conductive resin material is light in weight, has good mass productivity, and can be mass-produced at low cost. Suitable as a material. Since the conductive resin material contains a lubricant, the upper roller shaft 31 can smoothly rotate due to the lubrication performance of the contained lubricant.
[0083]
  Moreover, since the grounding structure 50 composed of the conduction part 51, the grounding part 53, the interposition part 52, and the grounding part 53 is formed by processing one metal plate, the grounding is performed by combining a plurality of members. Compared to the case of manufacturing the structure, the number of parts can be reduced to the limit, which can contribute to the reduction of parts cost and assembly cost.
[0084]
  By applying the grounding structure 50 to the image forming apparatus 10, the image forming apparatus 10 can effectively eliminate static electricity in a portion where various types of rollers in the apparatus are likely to generate static electricity. This makes it possible to eliminate defects in transfer processing due to static electricity.
[0085]
  The present invention is not limited to the above embodiment, and includes the following contents.
[0086]
  (1) In the above embodiment, the grounding structure 50 is applied to the paper transport unit 200 that supports the registration roller pair 132. However, in the present invention, the grounding structure 50 is applied only to the paper transport unit 200. The present invention is not limited to the application, and may be applied to rollers provided at various locations in the image forming apparatus 10.
[0087]
  (2) In the above-described embodiment, the oval insertion hole 511 whose shape is set so that the inner edge surface is in sliding contact with the outer peripheral surface of the bearing member 33 is employed as the inner fitting hole provided in the conducting portion 51. However, the present invention is not limited to the insertion hole 511 being an oval hole. First, various shapes (circular holes, elliptical holes, squares) in which the inner peripheral surface is not slidably in contact with the intake guide port 33 are described. It may be a literal internal hole such as a hole.
[0088]
  (3) In the above-described embodiment, the coil spring 65 is employed as the biasing member that presses the connection member main body 541 with the pressure contact structure 60. However, in the present invention, the biasing member that presses the connection member main body 541 is used. The spring is not limited to the coil spring 65, and various springs such as a leaf spring and a spiral spring can be employed, and an elastic member such as rubber or soft synthetic resin may be employed.
[0089]
  (4) In the above embodiment, an example in which the grounding structure 50 is applied to the image forming apparatus 10 has been described. However, the present invention applies only to the image forming apparatus 10. The present invention is not limited to this, and the present invention can also be applied to various devices such as a belt conveyor device in which a member in which an insulating material that is easily charged with static electricity is attached to the rotating shaft is employed.
[0090]
【The invention's effect】
  According to the grounding structure of the present invention, the bearing member that pivotally supports the rotating shaft is uniformly pressed by one or a plurality of pressing protrusions that protrude from the inner peripheral surface of the inner fitting hole of the conducting portion toward the center. Since it is in a supported state, it is possible to ensure a reliable electrical connection state between the conduction portion and the bearing member, and thereby the static electricity generated in the easily chargeable member provided on the rotating shaft is It is possible to reliably ground through the rotary shaft, the bearing member, and the pressure contact projection of the conductive portion, and it is possible to reliably prevent inconvenience due to charging of the easily chargeable member.
[0091]
  In addition, since the conducting portion can be applied to the rotating shafts having different diameters within the range of the elastic deformation of the pressure contact protrusion, it is not necessary to provide a dedicated conducting portion for each rotating shaft having different diameters. Can be made versatile.
[0092]
  According to the image forming apparatus of the present invention, since the grounding structure is employed, it is possible to effectively eliminate static electricity in a part where static electricity easily occurs including various rotating shafts in the image forming apparatus. Therefore, it is possible to reliably eliminate a transfer processing defect caused by static electricity.
[Brief description of the drawings]
FIG. 1 is a side sectional view illustrating an outline of an embodiment of an image forming apparatus to which a grounding structure according to the invention is applied.
FIG. 2 is a perspective view showing an embodiment of a frame.
3 is a perspective view showing a right part of the frame shown in FIG. 2. FIG.
4 is a partially enlarged perspective view taken along line A in FIG. 3;
FIG. 5 is a perspective view showing an embodiment of the grounding structure according to the present invention, showing a state where it is mounted on a bearing member.
FIG. 6 is a perspective view showing a positional relationship between a roller support block and a grounding structure.
FIG. 7 is a cross-sectional view in a side view in a state where a roller support block is mounted on a frame.
FIG. 8 is a perspective view showing a conventional grounding structure of a rotating shaft.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Image forming apparatus 11 Image forming unit
11Y Yellow unit 11M Magenta unit
11C Cyan unit 11K Black unit
111 Developing Device 112 Photosensitive Drum
113 Exposure unit 114 Charging unit
115 Cleaning Mechanism 12 Transfer Belt Unit
121 Base 122 Transfer belt
13 Paper Feed Unit 131 Transport Roller Pair
132 Registration roller pair 133 Driving roller
134 Followed roller 135 Transfer roller
14 Sheet storage unit 15 Fixing device
151 Fixing roller pair 16 Device body
161 discharge section
200 Paper transport unit 20 Frame
21 Side plate 22 Side plate body
23 Roller support 231 Shaft support groove
24 Shelf (grounding position) 241 Positioning protrusion
242 Screw hole 25 Guide part
26 Construction plate 27 Guide fin
28 Rib 29 Roller support block
291 Support block body 292 Front plate
293 Rear plate 294 Bridge plate
2941 Insertion recess 2942 Insertion hole
296 Tube 297 Grounding member clamping plate
298 square hole 299 circular hole
30 Upper roller 31 Upper roller shaft (rotating shaft)
32 Upper roller body 33 Bearing member
331 Flat surface 332 Flange
40 Lower roller 41 Lower roller shaft
42 Lower roller body 43 Bearing
44 Bearing support 50 Grounding structure
51 conduction part 511 insertion hole (internal fitting hole)
512 String edge 513 Pressure contact protrusion
514 Apex edge 515 Cut groove
52 Interposition part 53 Grounding part
531 Square Hole 532 Circular Hole
533 Anti-slip protrusion 54 Connection part
541 Connection unit body 542 Bending piece
60 pressure contact structure (biasing structure) 61 cylinder
62 Central cylinder 63 Front cylinder
64 Back cylinder 65 Coil spring

Claims (9)

A grounding structure for electrically grounding a rotating shaft that is rotatably supported around a shaft center via a bearing member on a synthetic resin frame, and a conductive portion that is externally fitted to the rotating shaft; A conducting portion connected to a predetermined grounding position and a conducting ground portion, and the conducting portion includes an inner fitting hole into which the bearing member is fitted, and a hole center from an inner peripheral surface of the fitting hole. One or a plurality of press contact protrusions protruding toward the direction and having a tip pressed against the bearing member, and conductive plastic deformation is possible between the conductive portion and the grounding portion. A grounding structure characterized in that an interposition part is provided . The ground portion, the ground structure of claim 1 Symbol mounting, characterized in that it has a connection portion connected to the frame. The grounding structure according to claim 2 , further comprising an urging structure that presses the connection portion against the frame . The bearing member is a grounding structure according to any one of claims 1 to 3, characterized in that it is formed by a conductive resin material. The grounding structure according to claim 4, wherein the conductive resin material contains a lubricant . The grounding structure according to claim 2 , wherein the conductive portion, the ground portion, the interposed portion, and the connection portion are formed by processing a single metal plate . 7. An image forming apparatus configured to form a toner image on a peripheral surface of a photosensitive drum by toner supplied from a developing device, and to transfer the toner image onto a sheet. images forming device you characterized in that grounding structure described is employed. The rotation axis is an image forming apparatus according to claim 7, wherein the der Rukoto those used rollers for paper transport. The rotating shaft is for one roller of a pair of paper conveying rollers, and this roller is made of a metal material, while the other roller has a roller body excluding the shaft made of an elastomer, the static electricity charged in the roller body, an image forming apparatus according to claim 8, wherein that you neutralization through the one roller.

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