JP4308631B2 - Development device - Google Patents

Description

  The present invention relates to an image forming apparatus, a facsimile apparatus, and a developing device applied to an image forming apparatus such as various printers.

  2. Description of the Related Art Conventionally, a developing device that supplies toner to a photosensitive drum in order to form a toner image on the photosensitive drum of the image forming apparatus based on input image information is known. This developing device has a box-shaped housing for containing a developer composed of toner and a carrier, and directs only the toner in the developer in the housing toward the electrostatic latent image formed on the peripheral surface of the photosensitive drum. A developing roller to be supplied, and a developer agitating unit that conveys the developer in the housing in a predetermined direction while agitating the developer in the housing. When the toner in the housing is consumed by the supply of toner to the photosensitive drum, the toner is replenished from the new toner cartridge into the housing by replacing the toner cartridge that is detachably attached to the housing. The developer agitating means agitates the developer in the housing and uniformly disperses the toner and the carrier which are constituent elements of the developer.

  The rotation direction of the developing roller is usually set so as to deliver the toner to the peripheral surface of the photosensitive drum in a state where the developer adhered to the peripheral surface is directed from the top to the bottom, and at the upper position of the peripheral surface. A layer thickness regulating blade for regulating the layer thickness of the developer is provided over substantially the entire length in the longitudinal direction. Since the installation position of the layer thickness regulating blade is set so as not to interfere with the photosensitive drum, it is inevitably set at a position immediately above the developing roller. As a result, the developing roller is approximately half in the circumferential direction. Is exposed to the outside from the housing.

  When the developing roller rotates in this state, the developer layer formed on the peripheral surface is exposed to the outside until it moves from the layer thickness regulating blade to the surface facing the photosensitive drum. Then, the toner scattered from the developer layer diffuses into the apparatus main body of the image forming apparatus, thereby causing a disadvantage that various precision devices in the apparatus main body are contaminated.

  In order to prevent such inconvenience, conventionally, a dust-proof cover is attached to a portion that is exposed to the outside of the developing roller and does not face the photosensitive drum. The toner scattered from the adjacent surface is prevented from diffusing into the apparatus main body.

Usually, such a dustproof cover is screwed to the developing device or integrated with the cover of the developing device. As what is screwed, what was described in patent document 1 can be mentioned, for example.
JP 1998-190246 A

  However, in the conventional system in which the dustproof cover is fixed to the housing of the developing device by screwing, prior operation before shipping (when the developer is loaded in the developing device, the peripheral surface of the developing roller The developer attached to the printer must be removed before shipping, and therefore the dust cover must be opened once) and the dust cover must be opened for maintenance work during use. Each time, troublesome screw removal and screwing must be performed, which leads to a problem that the maintenance work of the developing device becomes inferior.

  The pre-operation prior to shipment will be described in more detail. Some developing devices are pre-loaded with a developer before shipment. This is because the image forming apparatus is installed on the user side. This is because it is not necessary to perform troublesome charging work of the developer at the time of replacing the developing device. When the developing device loaded with the developer is shipped, there is a disadvantage that the developer adhering to the peripheral surface of the developing roller is scattered during transportation or handling. In order to eliminate such inconvenience, it is necessary to remove the developer adhering to the peripheral surface of the developing roller before shipping. For example, the dustproof cover once closed by screwing should be removed one by one. It had to be done with tedious work and open up, and improvements to this were envied.

  The present invention has been made in view of such a situation, and a developing device that can contribute to reduction in apparatus cost while ensuring good workability in advance operation before shipment and maintenance work after shipment. It is intended to provide.

According to the first aspect of the present invention, the photosensitive drum in the exposed surface exposed to the outside from a predetermined housing so that a part of the peripheral surface faces the peripheral surface of the photosensitive drum over substantially the entire length in the longitudinal direction. In a developing device comprising a developing roller that supplies toner to the photosensitive drum from a facing surface that faces the peripheral surface of the developing roller, an adjacent surface that is adjacent to the facing surface to prevent toner scattering from the exposed surface of the developing roller A toner scattering prevention cover that covers the adjacent surface, and the toner scattering prevention cover has a support shaft that is integrally formed between the covering posture that covers the adjacent surface and the open posture that opens the adjacent surface. together is rotatably supported by the posture changeably the support axis, having an open position maintaining unit for a state of being set to the open position is maintained the open position, the open position maintaining unit, Toner scattering prevention In a state where the bar is set to the open position, there is to maintain the open attitude of the toner scattering prevention cover by the reaction force from the housing by to elastically deform at least the support shaft, the support shaft concentric And an eccentric cam integral with the toner scattering prevention cover, and the eccentric cam is dimensioned so that the toner scattering prevention cover can be maintained in an open posture. A reinforcing portion is formed through the eccentric cam to provide a reaction force that elastically deforms the support shaft into an arcuate shape according to the rotation of the support shaft .

  By adopting such a configuration, the scattering of the toner from the adjacent surface located above the facing surface facing the photosensitive drum in the exposed surface exposed from the housing of the developing roller covers the adjacent surface. Since it is prevented by the toner scattering prevention cover, scattering of scattered toner into the main body of the developing device is prevented.

  The toner scattering prevention cover is pivotally supported around the support shaft so that the posture can be changed between a covering posture that covers the adjacent surface of the developing roller peripheral surface and an open posture that opens the adjacent surface. Compared to the conventional case where the toner scattering prevention cover is fixed to the housing with screws, the toner scattering prevention cover can be easily opened by rotating the support shaft during various maintenance operations. In addition, since the configuration is such that the open posture can be maintained, the toner scattering prevention cover can be maintained in the opening posture, thereby improving the workability of maintenance work performed by opening the toner scattering prevention cover.

Further , when the attitude of the toner scattering prevention cover that has been set to the covering attitude is changed to the opening attitude by rotating the cover around the support shaft in a predetermined direction, at least the toner scattering is prevented by the opening attitude maintaining unit provided in the toner scattering prevention cover. Since the prevention cover is elastically deformed, the opening posture of the toner scattering prevention cover is maintained by the reaction force of the elastic deformation, and the workability of the maintenance work of the developing device is improved accordingly.

Then , the toner scattering prevention cover that has been set to the covering attitude is rotated in a predetermined direction around the support shaft to change the attitude to the open attitude, so that the eccentric cam presses the housing and the toner scattering prevention cover is elastically deformed. The open position of the toner scattering prevention cover is maintained by the reaction force from the housing.

  Thus, by providing the toner scattering prevention cover with an eccentric cam that elastically deforms the housing by interference with the housing, the toner scattering prevention cover can be kept open with one touch without requiring extra parts such as a spring. This contributes to the improvement of workability during the maintenance work of the developing device and the reduction of the device cost.

According to a second aspect of the invention, organic in the invention of claim 1 Symbol placement, the toner scattering prevention cover is an engaging portion which detachably engages releasably in a part of the housing while being posture setting the coating position It is characterized by that.

  By adopting such a configuration, the engagement portion of the toner scattering prevention cover is engaged with a part of the housing in a state in which the toner scattering prevention cover is set to the covering posture, thereby covering the toner scattering prevention cover. Is stable.

  According to the first aspect of the present invention, compared to the conventional case where the toner scattering prevention cover is fixed to the housing with screws, the toner scattering prevention cover can be easily rotated around the support shaft during various maintenance operations. In addition to being easily opened by a moving operation, the toner scattering prevention cover can be kept in an open position, so that it is possible to improve the workability of developing device maintenance work performed by opening the toner scattering prevention cover. it can.

In addition , by changing the posture of the toner scattering prevention cover that has been set to the covering posture to the opening posture by rotating it in a predetermined direction around the support shaft, at least the toner scattering prevention cover is elasticized by the action of the opening posture maintaining unit. Therefore, the toner scattering prevention cover can be maintained in the open posture by the reaction force of the elastic deformation, and the workability of the maintenance work of the developing device can be improved accordingly.

Further , the eccentric scattering cam presses the housing and elastically deforms by rotating the toner scattering prevention cover, which has been set to the covering posture, around the support shaft in a predetermined direction and changing the posture to the open posture. The open posture of the toner scattering prevention cover can be maintained by the reaction force of the deformed housing.

According to the second aspect of the present invention, since the engaging portion of the toner scattering prevention cover engages with a part of the housing in a state where the toner scattering prevention cover is set to the covering posture, the covering of the toner scattering prevention cover is performed. The posture can be stabilized.

Before describing the developing device according to the present invention, the term “developer” in the present invention will be defined. “Developer” refers to a two-component mixture of “toner” and “magnetic carrier”. The “toner” is a fine powder having a particle size of about 6 to 12 μm in which additives such as a colorant, a charge control agent, and wax are dispersed in a binder resin. The “magnetic carrier” is a magnetic particle having a particle size of about 60 μm, such as Fe ₃ O ₄ , for charging the toner.

  The “toner” is a consumable that is appropriately replenished from the toner cartridge to the developing device, whereas the “carrier” is loaded in a predetermined amount in the developing device in advance, and is circulated and used without being consumed. Therefore, it is not normally replenished.

  FIG. 1 is a side view illustrating a color image forming apparatus of a quadruple tandem developing system to which a developing device 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 unit 15 disposed immediately downstream of the unit 12 (left side in FIG. 1) is formed by being mounted in a box-shaped device main body 16 having a rectangular parallelepiped shape in appearance.

  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 of the units 11Y, 11M, 11C, and 11K is positioned in a predetermined relative positional relationship with respect to the device main body 16 and each part, and is mounted in the device main body 16.

  Each unit 11Y, 11M, 11C, and 11K includes a developing device 20 and a photosensitive drum 111, respectively. Each photosensitive drum 111 is supplied with toner from the corresponding developing device 20 and rotates in the clockwise direction in FIG.

  A charger 112 is provided at a position on the upper left side in FIG. 1 of each photoconductor drum 111, and an exposure device 113 is provided at a position on the upper right side in FIG. Each photosensitive drum 111 is charged uniformly by the charger 112, and laser light based on image data input from a document image reading device (not shown) is charged from each exposure device 113. By irradiating the peripheral surface of the subsequent photosensitive drum 111, an electrostatic latent image is formed on the peripheral surface of each photosensitive drum 111. By supplying toner from the developing device 20 to the electrostatic latent image, a toner image is formed on the peripheral surface of the photosensitive drum 111.

  The transfer belt unit 12 is provided at a position below the image forming unit 11 so as to correspond to each photosensitive drum 111. 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 is transferred to a slightly upper position between the driving roller 133 provided at the left end of the base 121 in FIG. 1, the driven roller 134 provided at the right end, and between the driving roller 133 and the driven roller 134. The belt 122 is wound around a plurality of transfer rollers 135 disposed opposite to the respective photosensitive drums 111 via a belt 122, and circulates by the rotational driving of the driving roller 133.

  Each of the transfer rollers 135 is pressed against the corresponding photosensitive drum 111 via the transfer belt 122, so that the transfer from the photosensitive drum 111 to the sheet conveyed by the transfer belt 122 is reliably performed. It has become. Further, a cleaning device 114 for removing residual toner on the circumferential surface of the photosensitive drum 111 and cleaning the photosensitive drum 111 is provided at a lower left position in FIG. 1 of each photosensitive drum 111. The peripheral surface of the photosensitive drum 111 cleaned by the cleaning device 114 is directed to the charger 112 for a new charging process.

  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 sends it between the photosensitive drum 111 and the transfer belt 122. In the present embodiment, the transfer belt The 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 111. In addition, a registration roller pair 132 and the like for feeding the paper after positioning the paper are provided.

  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 111 of the image forming units 11Y, 11M, 11C, and 11K are sequentially transferred onto the paper during the passage.

  The sheet on which the toner image has been transferred is introduced into a fixing unit 15 having a fixing roller pair 151, and the color on which toner is fixed on the sheet by a heat fixing process by passing between the heated fixing roller pair 151. An image is formed. The sheet with the color image for 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.

  FIGS. 2 and 3 are perspective views showing an embodiment of the developing device 20 according to the present invention, which is suitable for application to the image forming apparatus 10, and FIG. FIG. 3 shows a state in which the toner scattering prevention cover 70 is set to the open posture. 4 is a cross-sectional view taken along the line AA of FIG. 2, and FIG. 5 is a perspective explanatory view for explaining the stirring and conveying action of the developer in the developing device 20. 2 to 5, 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 leftward, the + X direction is rightward, the -Y direction is forward, and the + Y direction is forward. It is called the back. In FIG. 5, the flow of the developer is indicated by a white arrow.

  As shown in these drawings, the developing device 20 includes an upper screw feeder 30 and a lower screw feeder 40 (FIG. 5) that circulate and convey the developer to a long housing 21 (FIGS. 2 to 4). Further, a pumping roller 50 (FIG. 5) that pumps the developer from the lower screw feeder 40 toward the upper screw feeder 30, and the toner in the developer that is being stirred and conveyed by the lower screw feeder 40 are moved around the photosensitive drum 111. A developing roller 60 (FIGS. 4 and 5) to be supplied to the surface is built in, and a toner scattering prevention cover 70 that covers the exposed surface of the developing roller 60 and prevents toner scattering is mounted outside the housing 21. It is formed by.

  The housing 21 includes a housing main body 22 having an upper surface opened, and a lid 29 that closes the upper surface opening of the housing main body 22. An opening / closing mechanism 291 for opening / closing a predetermined opening / closing plate is provided on the upper surface of the right end portion of the lid 29. The opening / closing mechanism 291 opens the opening / closing plate in conjunction with the mounting operation when a toner cartridge (not shown) for replenishing toner to the developing device 20 is mounted on the lid 29. When the cartridge is removed from the lid 29, the opening / closing plate is closed.

  Therefore, when the toner cartridge is attached to the developing device 20 via the lid 29, the toner from the toner cartridge is loaded into the housing main body 22, while the opening and closing of the toner cartridge is performed when the toner cartridge is removed from the lid 29. By closing the plate in conjunction with the removal of the toner cartridge, toner leakage from the toner cartridge is prevented.

  The housing body 22 includes a pair of side plates 23 in the width direction and a front plate 24 provided between the front edge portions of the side plates 23. A projecting plate portion 25 projecting outward is provided at a position that is approximately ¼ of the length dimension to the left from the right end portion of the front plate 24 and the left side plate portion. 23 is shaped so as to be able to face the protruding plate portion 25.

  In the front plate 24, a substantially lower half between the projecting plate portion 25 and the left side plate portion 23 is cut away as shown in FIG. 4, and the bottom plate 26 and the housing main body 22 are vertically moved. A lower stirring chamber 202 in which the lower screw feeder 40 and the developing roller 60 are mounted is formed in a space surrounded by a partition plate 27 partitioned in the width direction at an intermediate position in the direction, and an upper portion above the partition plate 27. An upper stirring chamber 201 in which the screw feeder 30 is mounted is formed.

  Further, on the right side of the upper stirring chamber 201 and the lower stirring chamber 202 (the front side of the drawing in the direction orthogonal to the drawing in FIG. 4), the upper screw feeder 30 communicates with the upper and lower stirring chambers 201 and 202. A right side portion of the lower screw feeder 40 and a developer pumping chamber 203 (FIG. 5) in which the pumping roller 50 is mounted are formed.

  The partition plate 27 is provided with a developer regulating blade 28 that regulates the layer thickness of the developer stacked on the peripheral surface of the developing roller 60 to a predetermined thickness in accordance with the rotation around the axis of the developing roller 60. ing. That is, the developer regulating blade 28 hangs down from the partition plate 27 toward the peripheral surface of the developing roller 60 and supplies the photosensitive drum 111 with the thickness dimension of the developer layer formed on the peripheral surface of the developing roller 60. The developer layer passes through a gap between the tip edge surface of the developer regulating blade 28 and the peripheral surface of the developing roller 60, and the predetermined layer thickness is controlled. The amount of drooping from the partition plate 27 is set so that

  As shown in FIG. 5, the upper screw feeder 30 is installed between the left and right side plate portions 23 (FIG. 2) by longitudinally cutting the upper stirring chamber 201 and the developer pumping chamber 203. The upper screw feeder 30 includes a screw shaft 31 having each end portion passing through each side plate portion 23 so as to be rotatable about an axis, and a spiral blade 32 formed in a spiral shape on the outer peripheral surface of the screw shaft 31. ing. In the present embodiment, as shown in FIG. 5, the spiral blade 32 is formed in a so-called right spiral so as to extend clockwise (clockwise) when viewed from the end surface of the screw shaft 31. Accordingly, when the upper screw feeder 30 rotates counterclockwise around the screw shaft 31 in FIG. 5, the developer is conveyed leftward in the upper stirring chamber 201.

  As shown in FIG. 5, the lower screw feeder 40 is installed between the left and right side plate parts 23 (FIG. 2) by longitudinally cutting the lower stirring chamber 202 and the developer pumping chamber 203. The lower screw feeder 40 includes a screw shaft 41 in which each end portion passes through each side plate portion 23 so as to be rotatable around an axis, and a spiral blade 42 formed in a spiral shape on the outer peripheral surface of the screw shaft 41. ing. In the present embodiment, as shown in FIG. 5, the spiral blade 42 is formed by a left spiral opposite to the spiral blade 32 of the upper screw feeder 30. Therefore, when the lower screw feeder 40 rotates counterclockwise around the screw shaft 41 in FIG. 5, the developer is conveyed rightward in the lower stirring chamber 202.

  The pumping roller 50 pumps up the developer located in the developer pumping chamber 203 to the upper stirring chamber 201 through a pumping conveyance path (not shown). As shown in FIG. It is provided behind the intermediate position between the right and left portions of 30,40. The scooping roller 50 is in close contact with the scooping roller shaft 51 extending in the left-right direction, a scooping roller main body 52 that is concentrically and integrally fitted to the scooping roller shaft 51, and the scooping roller main body 52. And a covering tube 53 that is externally fitted in a state.

  The pumping roller main body 52 has a plurality of pairs of N poles and S poles formed on the outer peripheral surface thereof at equal pitches in the circumferential direction, and the developer is placed between these N poles and S poles. It is attracted to the outer peripheral surface of the pumping roller 50 in a state along the magnetic field lines to be formed. When the pumping roller 50 rotates around the pumping roller shaft 51 in the counterclockwise direction in FIG. 5, the magnetic carrier in the developer is attracted to the outer peripheral surface of the pumping roller main body 52 through the covering tube 53, Toner accompanies the magnetic carrier, and eventually the developer composed of the magnetic carrier and toner is pumped up into the upper stirring chamber 201.

  In the present embodiment, the coated tube 53 is a so-called heat-shrinkable synthetic resin tube that shrinks when heated. The heat shrinkable tube whose inner diameter is set slightly larger than the outer diameter of the pumping roller main body 52 is loosely fitted to the pumping roller main body 52 and then subjected to a heat treatment such as blowing hot air. The tube is heat-shrinked and comes into close contact with the outer peripheral surface of the pumping roller main body 52, thereby forming a covered tube 53.

  As shown in FIG. 5, the leading edge of a scraper 54 made of a synthetic resin film is brought into contact with the outer peripheral surface of the scooping roller 50, and the peripheral surface of the covering tube 53 is brought into contact with the scraper 54. The developer adhering to is scraped off.

  2 to 5, the developing roller 60 is located in the lower stirring chamber 202 (FIGS. 4 and 5), and the left side plate portion 23 and the protruding plate portion 25 are disposed in front of the lower screw feeder 40. And a developing roller body 61 that is concentrically mounted on the developing roller shaft 61 and is externally fitted so as to be integrally rotatable.

  In the developing roller main body 62, a plurality of magnetic poles are formed over the entire circumference along the peripheral surface from the inside, and the toner is developed by attracting the carrier by the attracting force of these magnetic poles and entraining the toner with this. It is applied uniformly and effectively to the peripheral surface of the roller body 62.

  The developing roller 60 rotates around the developing roller shaft 61 in the counterclockwise direction in FIG. 5. The developing roller 60 is laminated on the peripheral surface of the developing roller main body 62 by the rotation and is predetermined by the developer regulating blade 28. The developer whose thickness is regulated is opposed to the peripheral surface of the photosensitive drum 111 that rotates clockwise around the axis, and only a part of the toner in the developer is exposed along the electrostatic latent image. While being supplied to the body drum 111, the carrier in the developer and the remaining toner are collected in the lower stirring chamber 202 while remaining attached to the peripheral surface of the developing roller main body 62.

  In this embodiment, as shown in FIGS. 2 and 3, a joint member 611 is provided at the left end portion of the developing roller shaft 61 concentrically with the developing roller shaft 61, and the joint member 611 has an unillustrated drive. By connecting the drive shaft of the motor, the drive motor is driven to rotate in a predetermined direction. The rotation of the developing roller shaft 61 via the joint member 611 is transmitted to the upper screw feeder 30 and the lower screw feeder 40 via a gear mechanism (not shown) provided at an appropriate position on the left side plate portion 23 of the developing device main body 21. At the same time, the driving of any one of the upper screw feeder 30 and the document presence / absence detecting means 40 is driven by the pumping roller 50 via a gear mechanism (not shown) provided at the right end of the document feeder 20. It is to be transmitted.

  Hereinafter, the developer stirring / conveying operation in the developing device 20 will be described with reference to FIG. 5 and FIGS. 1 to 4 as necessary. First, when toner is loaded from a toner cartridge (not shown) to the right end of the upper stirring chamber 201 of the developing device main body 21 via the opening / closing mechanism 291 of the lid 29 (FIG. 2), the toner is supplied to the upper screw feeder. As indicated by the white arrow with the carrier by the rotation of 30 around the screw shaft 31 in the counterclockwise direction, the carrier is conveyed while being stirred leftward in the upper stirring chamber 201.

  Then, the developer conveyed to the left end portion in the upper stirring chamber 201 falls into the lower stirring chamber 202 from the communication opening 271 opened at the left end portion of the partition plate 27 (FIG. 4), and this time, the lower screw With the rotation of the feeder 40 around the screw shaft 41 in the counterclockwise direction, the spiral blade 42 conveys the lower stirring chamber 202 toward the right. During this conveyance, a part of the developer is supplied to the peripheral surface of the developing roller 60 and is used for toner image formation on the peripheral surface of the photosensitive drum 111. Of the developer adhering to the peripheral surface of the developing roller 60, only the toner is supplied to the photosensitive drum 111, and the carrier is collected and returned to the lower stirring chamber 202 for circulation.

  The remaining developer that has not been supplied to the developing roller 60 in the lower stirring chamber 202 is conveyed through the lower stirring chamber 202 to the developer pumping chamber 203 by the rotation of the lower screw feeder 40, where the pumping roller 50 As a result of the rotation in the counterclockwise direction, the developing carrier is guided by the magnetic lines of force from the magnetic poles of the pumping roller main body 52 and pumped up into the upper stirring chamber 201. The developer pumped up into the upper stirring chamber 201 is conveyed toward the left again by the rotation of the upper screw feeder 30 and circulates in the developing device main body 21.

  The developer pumped up by the counterclockwise rotation of the pumping roller 50 is projected from the partition plate 27 (FIG. 4), which is the bottom plate of the upper stirring chamber 201, toward the peripheral surface of the pumping roller 50, and Since the tip edge is scraped off by the scraper 54 in contact with the peripheral surface of the pumping roller 50 at the contact position Q (FIG. 5), the aggregation of the developer on the peripheral surface of the pumping roller 50 is surely prevented. be able to.

  In the present invention, a toner scattering prevention cover 70 as shown in FIGS. 2, 3, and 4 is installed between the left side plate portion 23 and the protruding plate portion 25, and this toner scattering prevention cover 70. As a result, a part of the outer peripheral surface exposed to the outside from the lower stirring chamber 202 of the developing roller 60 (adjacent surface S2 adjacent to the upper edge of the opposing surface S1 facing the photosensitive drum 111) is covered by the toner scattering prevention cover 70. Thus, the toner scattered from the adjacent surface S2 of the developing roller 60 is prevented from diffusing into the device main body 16 of the image forming apparatus 10.

  FIG. 6 is a perspective view showing an embodiment of the toner scattering prevention cover 70, and FIG. 7 is a partially cutaway enlarged perspective view thereof. 6 and 7 are the same as those shown in FIG.

  The toner scattering prevention cover 70 is integrally formed by injection molding using a predetermined synthetic resin material as a raw material, and is installed between the left side plate portion 23 and the protruding plate portion 25 in the housing 21. Shaft body (support shaft) 71, a base end side dustproof plate 72 extending in a radial direction from the shaft body 71, and a clockwise direction from the front end edge of the base end side dustproof plate 72 The front end side dust-proof plate 73 extending in the width direction and extending in a state of being bent at approximately 45 ° toward the front, and the shaft 71 projecting in the radial direction from the shaft body 71 toward the front plate 24 of the housing body 22. A predetermined number of eccentric cams (open posture maintaining portions) 74 are provided.

  A reinforcing square member 75 extending in the longitudinal direction integrally bulges on the peripheral surface of the shaft body 71, and a plurality of proximal ribs at a predetermined pitch from the reinforcing square member 75 in the radial direction of the shaft body 71. The base end side dustproof plate 72 is integrally supported by the reinforcing square member 75 and the plurality of base end side ribs 751 so that a predetermined strength is maintained.

  Further, an intermediate reinforcing square member 76 having the same length as the reinforcing square member 75 is interposed between the distal end edge portion of the proximal end side dustproof plate 72 and the proximal end edge portion of the distal end side dustproof plate 73. An edge dam plate 77 having the same length as that of the intermediate reinforcing square member 76 protrudes counterclockwise from the distal end edge portion of the distal end side dustproof plate 73. Further, the same number of front end side ribs 761 as the base end side ribs 751 are provided at equal pitches in the longitudinal direction between the edge dam plate 77 and the intermediate reinforcing square member 76, and toner is formed by these ribs and the reinforcing square member. The scattering prevention cover 70 is structurally strong.

  On the outer surface side of the edge weir plate 77, toner scattering made of a synthetic resin film (in this embodiment, a polyurethane film having a thickness of 0.1 to 0.2 mm is employed). A prevention film 771 is affixed, and the front edge portion of the edge weir plate 77 is brought into contact with the peripheral surface of the photosensitive drum 111 by the toner scattering prevention film 771, whereby the adjacent surface S 2 of the developing roller 60 (FIG. 4). ) Is more effectively prevented from diffusing out of the toner scattering prevention cover 70.

  Each end of the shaft body 71 protrudes in the opposite direction from the base end side dustproof plate 72, and each protruding portion is drilled in the left side plate portion 23 and the protruding plate portion 25. When the toner scattering prevention cover 70 is rotatably inserted into the support hole, the covering posture shown in FIG. 2 covering the adjacent surface S2 (FIG. 4) of the developing roller 60 and the adjacent surface S2 are opened. The posture can be changed between the open posture shown in FIG.

  The eccentric cam 74 is formed by projecting from the peripheral surface of the shaft body 71 in a direction substantially opposite to the base end side rib 751 corresponding to any base end side rib 751. In the present embodiment, two eccentric cams 74 are provided corresponding to the third base end side ribs 751 from the left and right ends of the shaft body 71.

On the other hand, as shown in FIG. 7, the front plate 24 of the housing body 22 is provided with a rectangular thick portion (reinforcing portion) 241 bulging outwardly at a portion facing the eccentric cam 74. The thick portion 241 is pressed by the eccentric cam 74 in a state where the toner scattering prevention cover 70 is set to the open posture.

  The eccentric cam 74 is in contact with and pressed against the front plate 24 of the housing main body 22 with the toner scattering prevention cover 70 set to the open posture, whereby the shaft body 71 is elastically deformed to be bent in an arcuate shape, The dimension and shape are set so that the shaft 71 receives a force from the front plate 24 in the clockwise direction around the axis by the reaction force. Therefore, in the state where the toner scattering prevention cover 70 is opened and the posture is set to the open posture, the open posture is maintained.

  In the toner scattering prevention cover 70 configured as described above, an engagement portion 80 that engages with the left side plate portion 23 and the protruding plate portion 25 of the housing body 22 is provided at each end portion of the front end side dustproof plate 73. The engagement position of the toner scattering prevention cover 70 is stabilized by the engagement of the engagement portion 80 with the side plate portion 23 and the protruding plate portion 25.

  FIG. 8 is a perspective view showing an embodiment of the engaging portion 80. In FIG. 8, the direction display by X and Y is the same as in FIG. As shown in this figure, the engaging portion 80 includes a pair of front and rear L-shaped projecting pieces 81 projecting outward from the front end side of the end portion of the toner scattering prevention cover 70 in the width direction, The L-shaped projecting piece 81 includes a plate-shaped operation piece 82 projecting outward from the front end edge portion. Each L-shaped projecting piece 81 is bent in a side view (viewed from the Y-Y direction) with the tip-side dust-proof plate 73 and a portion flush with the tip side dust-proof plate 73 and downward in FIG. The operation piece 82 protrudes outward in parallel with the front-end dustproof plate 73 from the lower end edge of the portion bent downward of the L-shaped protruding piece 81. Is formed.

  In addition, a square window 83 is formed in a space surrounded by the pair of L-shaped projecting pieces 81 and the operation piece 82, and the operation piece 82 is disposed between the front end edges of the pair of L-shaped projecting pieces 81. A locked edge 821 formed by one edge is provided.

  On the other hand, the protruding plate portion 25 of the housing body 22 can be fitted into the square window 83 at a position corresponding to the square window 83 of the engaging portion 80 and the operation piece 82 of the engaging portion 80 is locked. A locking projection 251 corresponding to the edge 821 is provided. The locking projection 251 is shaped so that its lower surface engages with the locked edge portion 821 while being loosely fitted to the square window 83, and the upper surface thereof faces outward. A guide inclined surface 252 formed in a first descending manner is formed.

  According to the engagement portion 80 having such a configuration, the locked edge portion of the operation piece 82 of the engagement portion 80 is changed by closing the toner scattering prevention cover 70 that has been set to the open posture and changing the posture to the covering posture. 821 is guided to the guide inclined surface 252 of the locking projection 251 of the protruding plate portion 25, whereby the L-shaped protruding piece 81 is elastically deformed so as to open its L-shape, and in this state the locking projection 251 is moved. By restoring the L-shaped projecting piece 81 to its original state by passing, the locked edge portion 821 is locked to the locking protrusion 251 as shown in FIG. Is maintained in a stable state.

  In order to release the engagement of the engaging portion 80 with respect to the locking projection 251, the operation piece 82 may be pushed upward with a finger. By doing so, the L-shaped projecting piece 81 is elastically deformed in the direction of opening the L-shape, so that the locking of the locked edge portion 821 with respect to the locking projection 251 is released, thereby the toner scattering prevention cover. 70 can be opened.

  FIG. 9 is a side sectional view for explaining the operation of the open posture maintaining structure of the toner scattering prevention cover 70 according to the present invention. FIG. 9A is a diagram illustrating the posture setting of the toner scattering prevention cover 70 in the covering posture. (B) shows a state in which the toner scattering prevention cover 70 is set to the open posture.

  First, in the state shown in FIG. 9A in which the toner scattering prevention cover 70 is set to the covering posture, the eccentric cam 74 protrudes upward from the shaft body 71, thereby the front plate of the housing body 22. It is in the state which does not act with respect to the thick part 241 of 24.

  In this state, when the toner scattering prevention cover 70 set in the covering attitude is rotated clockwise around the shaft body 71, the eccentric cam 74 of the toner scattering prevention cover 70 is thickened on the front plate 24 of the housing body 22. The shaft body 71 is bent and elastically deformed by a reaction force by pressing the portion 241 and bending.

  When the toner scattering prevention cover 70 is set to the open posture, the shaft center O of the shaft body 71 and the eccentric cam 74 are in contact with the front plate 24 as shown in FIG. A straight line connecting the contact P is located below a perpendicular line extending from the axis O to the front plate 24, and a reaction force F received from the front plate 24 of the housing body 22 due to the elastic deformation of the shaft 71. The line of force is located below the axis O. Therefore, the reaction force F acts as a force (moment) that rotates the eccentric cam 74 around the axis O of the shaft body 71 in the clockwise direction. The moment in the clockwise direction around the axis O due to the reaction force F is greater than the moment of the toner scattering prevention cover 70 attempting to rotate counterclockwise around the axis O under its own weight. The elastic force of bending is set. Therefore, the toner scattering prevention cover 70 overcomes the force to be closed and maintains the open posture.

  In the present invention, as described in detail above, a part of the peripheral surface is exposed to the outside from the housing 21 so as to face the peripheral surface of the photosensitive drum 111 over substantially the entire length in the longitudinal direction. Of the developing roller 60 that supplies toner to the photosensitive drum 111 from the facing surface S1 that faces the peripheral surface of the photosensitive drum 111, and the toner scattering prevention that covers the adjacent surface S2 located above the facing surface S1 of the developing roller 60 The developing device 20 includes a cover 70.

  The toner scattering prevention cover 70 is pivotally supported around the shaft body 71 so as to be changeable between a covering posture that covers the adjacent surface S2 and an open posture that opens the adjacent surface S2. An open posture maintaining unit that maintains the open posture in a state where the posture is set to the open posture is provided in the shaft body 71, and the open posture maintaining unit is configured so that the toner scattering prevention cover 70 is set in the open posture. Since the open posture of the toner scattering prevention cover 70 is maintained by a reaction force caused by elastically deforming the upper guide plate 71 of the maintenance member 70, the toner scattering prevention cover 70 set in the covering posture is attached to the shaft. By changing the posture to the open posture by rotating around the body 71, the open posture maintaining portion provided in the toner scattering prevention cover 70 interferes with the housing body 22 and The shaft body 71 of the toner scattering prevention cover 70 is elastically deformed, it receives a reaction force of the elastic deformation of the front plate 24 of the housing body 22, thereby releasing position of the toner scattering prevention cover 70 is maintained.

  Therefore, it is not necessary to remove the screw-splashed toner scattering prevention cover 70 as conventionally done, and the workability of the maintenance work of the developing device 20 can be improved accordingly.

  The open posture maintaining portion is formed by an eccentric cam 74 that is concentric with the shaft body 71 and integral with the toner scattering prevention cover 70, and the eccentric cam 74 is in a state in which the toner scattering prevention cover 70 is set in the open posture. Since the dimensions of the shaft body 71 are elastically deformed by pressing the housing main body 22 at the same time, the structure of the open posture maintaining member is simplified, and toner scattering that has been set to the covering posture is prevented. By rotating the cover 70 around the shaft body 71 in a predetermined direction and changing the posture to the open posture, the eccentric cam 74 presses the housing body 22 and elastically deforms the shaft body 71 of the toner scattering prevention cover 70. The toner scattering prevention cover 70 can be reliably maintained in the open posture by the reaction force from the housing body 22 due to the above.

  Further, since the toner scattering prevention cover 70 is provided with an engaging portion 80 that is detachably engaged with a part of the housing main body 22 in the state where the covering attitude is set, the toner scattering prevention cover 70 is covered. With the posture set, the engaging portion 80 of the toner scattering prevention cover 70 engages with a part (the locking projection 251) of the housing main body 22, thereby stabilizing the covering posture of the toner scattering prevention cover 70. be able to.

  The present invention is not limited to the above embodiment, and includes the following contents.

  (1) In the above-described embodiment, the eccentric cam 74 protruding from the shaft body 71 is employed as the open posture maintaining portion that maintains the open posture of the toner scattering prevention cover 70. The maintaining portion is not limited to the eccentric cam 74. For example, the shaft body 71 may be formed in a crankshaft shape, and the open posture maintaining portion may be configured by the crank of the crankshaft.

  (2) In the above-described embodiment, the thick portion 241 is formed on the front plate 24 of the housing body 22 at the portion where the eccentric cam 74 of the toner scattering prevention cover 70 contacts. Is not essential, and the thick portion 241 is not particularly required if the front plate 24 has sufficient strength to withstand the pinpoint pressing by the eccentric cam 74.

  (3) In the above embodiment, a color image forming apparatus of a quadruple tandem developing system is cited as the image forming apparatus 10 to which the developing device 20 is applied. However, in the present invention, an image to which the developing device 20 is applied. The forming apparatus 10 is not limited to a quadruple tandem development type color image forming apparatus, and may be applied to a so-called monochrome image forming apparatus having only black color, for example.

  (4) In the above-described embodiment, the developing device 20 is provided with the screw feeders 30 and 40 above and below, but in the present invention, the developing device 20 has the screw feeders 30 and 40 above and below. The upper screw feeders may be arranged side by side in the lateral direction. Moreover, both the first and second stirring means are not limited to being screw feeders, and either one may be a screw feeder or neither may be a screw feeder. Moreover, what combined the fin-shaped thing to the axis | shaft and provided the conveyance property may be attached, and this may be employ | adopted as a stirring conveyance means.

  (5) In the above embodiment, the toner scattering prevention film 771 is affixed to the edge barrier plate 77 of the toner scattering prevention cover 70. However, in the present invention, the toner scattering prevention film 771 is attached to the edge barrier plate 77. In the case where the gap between the front edge of the edge weir plate 77 and the peripheral surface of the photosensitive drum 111 is extremely narrow, the toner scattering prevention film 771 is formed. It does not have to be provided.

  (6) In the above-described embodiment, in order to stabilize the covering posture of the toner scattering prevention cover 70, the toner scattering prevention cover 70 is provided with the engaging portion 80 that engages with the locking protrusion 251 of the protruding plate portion 25. However, the present invention is not limited to the provision of the engaging portion 80 in the toner scattering prevention cover 70, and the covering posture of the toner scattering prevention cover 70 by the biasing force of a biasing means such as a coil spring, for example. Other methods may be employed, such as stabilizing the toner scattering prevention cover 70, mounting a weight on the toner scattering prevention cover 70, and stabilizing the covering posture of the toner scattering prevention cover 70 by the weight of the weight.

  (7) In the above embodiment, the developer is composed of toner and carrier, but the present invention is not limited to the developer composed of toner and carrier. Alternatively, the developer may be composed only of toner.

  (8) In the above-described embodiment, the toner scattering prevention cover 70 is set in the open posture, and the contact point P of the eccentric cam 74 is separated from the housing body 22 as shown in FIG. Due to the force F, the toner scattering prevention cover 70 is maintained in the open posture in an attempt to rotate clockwise (opening direction) around the axis O of the shaft body 71 (that is, the force is applied). However, instead of this, when the toner scattering prevention cover 70 is in an intermediate position between the covering position and the opening position, the front plate 24 of the housing main body 22 is set. A so-called click structure in which the contact point P is provided at a position where the contact point P comes into contact with the head may be employed.

  In this way, when the toner scattering prevention cover 70 rotates slightly in the direction toward the open posture with the intermediate posture as a boundary, the contact point P continues to receive a force from the front plate 24 toward the open posture. When the toner scattering prevention cover 70 rotates slightly in the direction toward the covering posture with the intermediate posture as a boundary, the contact point P continues to receive a force toward the covering posture from the front plate 24. The cover 70 is stable in both the open posture and the covering posture.

1 is a side view illustrating a color image forming apparatus of a quadruple tandem developing system to which a developing device according to the present invention is applied. FIG. 2 is a perspective view showing an embodiment of the developing device according to the present invention, and shows a state in which the toner scattering prevention cover is set to a covering posture. FIG. 2 is a perspective view showing an embodiment of the developing device according to the present invention, and shows a state in which the toner scattering prevention cover is set to an open posture. It is the sectional view on the AA line of FIG. FIG. 6 is a perspective explanatory view for explaining the stirring and conveying action of the developer in the developing device. FIG. 6 is a perspective view illustrating an embodiment of a toner scattering prevention cover. FIG. 7 is a partially cutaway enlarged perspective view of the toner scattering prevention cover shown in FIG. 6. It is a perspective view which shows one Embodiment of an engaging part. FIG. 7 is a side sectional view for explaining the function of the toner scattering prevention cover open posture maintaining structure according to the present invention, and (A) is a state in which the toner scattering prevention cover is set to a covering posture (B) ) Shows a state in which the toner scattering prevention cover is set to the open posture.

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 Photosensitive drum 112 Charger 113 Exposure device 114 Cleaning device 12 Transfer belt unit 121 Base 122 Transfer belt 13 Paper feed Unit 131 Conveying roller pair 132 Registration roller pair 133 Driving roller 134 Driven roller 135 Transfer roller 14 Paper storage unit 15 Fixing unit 151 Fixing roller pair 16 Main body 161 Discharging unit 20 Developing device 201 Upper stirring chamber 202 Lower stirring chamber 203 Developer pump Raising chamber 21 Housing 22 Housing body 23 Side plate portion 24 Front plate
241 Thick part (reinforcement part)
25 Projecting plate portion 251 Locking projection 252 Guide inclined surface 26 Bottom plate 27 Partition plate 271 Communication opening 28 Developer regulating blade 29 Cover body 291 Opening / closing mechanism 30 Upper screw feeder 31 Screw shaft 32 Spiral blade 40 Lower screw feeder 41 Screw shaft 42 Spiral blade 50 Pumping roller 51 Pumping roller shaft 52 Roller body 53 Cover tube 54 Scraper 60 Developing roller 61 Developing roller shaft 62 Developing roller body 70 Toner scattering prevention cover 71 Shaft body (support shaft) 72 Base end side dustproof plate 73 Tip Side dustproof plate 74 Eccentric cam (open posture maintaining part)
75 Reinforced square member 751 Base end side rib 76 Intermediate reinforcing square member 761 Tip side rib 77 Edge dam plate 771 Toner scattering prevention film 80 Engagement portion 81 L-shaped protruding piece 821 Locked edge portion 82 Operation piece 83 Square window O Axis center P Contact point Q Contact position S1 Opposite surface S2 Adjacent surface

Claims (2)

A facing surface that faces the circumferential surface of the photosensitive drum among exposed surfaces exposed from the predetermined housing so that a part of the circumferential surface faces the circumferential surface of the photosensitive drum over substantially the entire length in the longitudinal direction. In a developing device comprising a developing roller for supplying toner to the photosensitive drum from
A toner scattering prevention cover that covers an adjacent surface adjacent to the facing surface to prevent toner scattering from the exposed surface of the developing roller;
The toner scattering prevention cover has a support shaft that is integrally formed, wherein a covering position covering the adjacent surfaces, times the posture changeably the support axis between the open position to open said abutment surface It is pivotally supported and has an open posture maintaining unit that maintains the open posture in a state where the posture is set to the open posture,
The open posture maintaining unit maintains the open posture of the toner scattering prevention cover with a reaction force from the housing by elastically deforming at least the support shaft in a state where the toner scattering prevention cover is set to the open posture. An eccentric cam that is concentric with the support shaft and integral with the toner scattering prevention cover,
The eccentric cam is dimensioned so that the toner scattering prevention cover can be maintained in an open posture.
The developing device according to claim 1 , wherein the housing is provided with a reinforcing portion that provides a reaction force that elastically deforms the support shaft into an arcuate shape according to the rotation of the support shaft via the eccentric cam. The developing device according to claim 1, wherein the toner scattering prevention cover includes an engaging portion that is detachably engaged with a part of the housing in a state where the covering posture is set.

Images