JP2005128056A - Development apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a development apparatus capable of effectively restraining the irregular supply of toner by surely preventing the flocculation of developer. <P>SOLUTION: The development apparatus is equipped with a toner reservoir chamber 22 and a developer stirring chamber 23 installed adjacently to the chamber 22 through a partition wall 24, is provided with a connection aperture 26 through which the chamber 22 and the chamber 23 communicate with each other on the partition wall 24, and also a magnet roller 40 facing to the aperture 26 and feeding the developer to the chamber 23 in the chamber 22, and is constituted so that prescribed stirring processing is performed to the toner fed to the chamber 23 by the roller 40. It is provided with a guide plate 90 whose base end side is fixed on the inner wall surface of the aperture 26 and whose leading end side pierces through the aperture 26 and projects to the chamber 23 side at the edge part of the aperture 26 opposed to the circumferential surface of the roller 40, whereby the flocculated toner is prevented from being supplied to the chamber 23 side by the plate 90. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

  Conventionally, a developing device as described in Patent Document 1 is known. This developing device is applied to an image forming apparatus such as a copying machine, a facsimile machine, and various printers. A toner as a component of a developer is applied to a peripheral surface of a photosensitive drum built in the main body of the apparatus. It is used to supply. In such a developing device, a storage chamber that receives and temporarily stores toner from the toner cartridge, a stirring chamber that is adjacent to the storage chamber through a communication opening provided in the partition wall, and stirs the developer; It is provided with a feeding roller that is disposed facing the communication opening in the storage chamber and feeds the toner toward the stirring chamber.

  Then, the developer in the storage chamber is guided to the peripheral surface of the feeding roller that rotates about the axis, and is introduced into the stirring chamber through the communication opening, where it is stirred and uniformly mixed by a predetermined stirring member. Then, the toner is supplied from the peripheral surface of the developing roller rotating around the axis to the peripheral surface of the photosensitive drum.

  The developer is a so-called two-component developer (two-component developer) in which resin particles (toner) in which a color material such as carbon black is dispersed in a resin and a magnetic carrier are mixed. On the other hand, the feeding roller employs a so-called magnet roller whose circumferential surface is magnetized, and the carrier is magnetically attached to the circumferential surface of the magnet roller, so that the developer can be efficiently fed into the stirring chamber. It is made to be done.

When the developer stacked on the peripheral surface of the feeding roller (magnet roller) passes through the communication opening, it interferes with the opposite edge of the communication opening, so that the toner on the upper layer in the developer layer is scraped off. The toner that has been scraped off is introduced into the agitating chamber as well as having a predetermined layer thickness. By adopting the feeding roller composed of such a magnet roller, the feeding of the toner from the storage chamber to the stirring chamber is reliably performed in a stable state.
JP-A-7-13426

  By the way, in the conventional developing device described in Patent Document 1, the upper toner layer in the developer layer laminated on the peripheral surface of the feeding roller is scraped off by interference with the edge of the communication opening. At that time, what remains on the feeding roller side hardens and aggregates. The agglomerated toner often peels off and is supplied to the agitation chamber, and such agglomerated toner is difficult to disperse even by agitation operation by the agitation member. When the agent is present, the toner does not mix with the carrier sufficiently uniformly and becomes non-uniform.

  When the toner is supplied to the photosensitive drum through the developing roller in such a non-uniform state, unevenness (so-called replenishment unevenness) occurs in the toner image on the photosensitive drum, and thereby a good transfer image is formed on the sheet. There is a disadvantage that it cannot be formed.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a developing device capable of reliably preventing toner aggregation and thereby effectively suppressing toner replenishment unevenness. Yes.

  The developing device according to the first aspect of the present invention includes a storage chamber for storing toner, an agitation chamber for agitating a developer in which toner and a carrier adjoining the storage chamber through a partition wall are mixed. The partition wall is provided with a communication opening for communicating the storage chamber and the stirring chamber, and the storage chamber is provided with a feed roller for feeding the toner into the stirring chamber facing the communication opening. In the developing device configured to perform a predetermined stirring process on the toner fed into the stirring chamber by the feeding roller and supply the toner to the circumferential surface of the photosensitive drum, the communication opening facing the circumferential surface of the feeding roller A guide plate that protrudes toward the stirring chamber side with the base end side fixed to the inner wall surface of the communication opening and the distal end side penetrating the communication opening is provided at the edge portion.

  A developing apparatus according to a second aspect of the present invention is the developing apparatus according to the first aspect, wherein the guide plate is formed of polyurethane or polyethylene terephthalate.

  According to the developing device of the first aspect, the tip side of the edge of the communication opening facing the peripheral surface of the feeding roller that faces the communication opening and feeds the toner from the storage chamber to the stirring chamber faces the stirring chamber side. A guide plate projecting toward the surface is provided. This guide plate is formed of an elastic material, and toner is guided to its peripheral surface by the rotation of the feeding roller, and is communicated from the storage chamber to the stirring chamber via the opening. When being fed, it is possible to effectively prevent the developer aggregate from being introduced into the stirring chamber by a guide plate provided at the edge of the communication opening.

  Therefore, when the aggregated toner aggregate is introduced into the agitation chamber, toner replenishment unevenness with respect to the photosensitive drum occurs, thereby eliminating the inconvenience that the paper cannot be properly transferred. .

  According to the developing device of claim 2, the guide plate is formed of polyurethane or polyethylene terephthalate, and these resins are provided with an appropriate elastic force by being formed into a plate shape having a predetermined thickness. Therefore, it is excellent as a material for the guide plate, and the aggregated toner aggregate that has not been introduced into the stirring chamber can be returned to the feeding roller side.

Before describing the developing device according to the present invention, the term “developer” in the present invention will be defined. The “developer” is a two-component mixture of “toner” and “magnetic carrier” mixed with the toner. 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 200 μm, such as Fe ₃ O ₄ , for charging the toner.

  FIG. 1 is a side sectional view showing an outline of an embodiment of an image forming apparatus to which a developing device according to the present invention is applied. As shown in FIG. 1, in the image forming apparatus 10, an image forming unit 12 that forms a toner image on the peripheral surface of the photosensitive drum 121, and a toner image formed on the peripheral surface of the photosensitive drum 121 are transferred. At the same time, a transfer unit 13 for transferring the toner image onto the paper P and a fixing unit 14 for fixing the transfer image on the paper onto which the toner image has been transferred by the transfer unit 13 form a box-shaped device body 11. A paper cassette mounting portion 15 in which a paper cassette (not shown) is mounted is formed in the lower right portion of FIG. 1 in the apparatus main body 11 and is further provided with a sheet P discharged from the upper surface of the apparatus main body 11. A paper discharge unit 16 having a paper discharge tray 161 is formed.

  In the present embodiment, the image forming unit 12 includes a yellow unit 12Y as the developing device 20 according to the present invention and a magenta unit that are sequentially arranged from the upstream side (the right side in FIG. 1) to the downstream side. 12M, a cyan unit 12C, and a black unit 12K. The units 12Y, 12M, 12C, and 12K are positioned with a predetermined relative positional relationship with respect to the circumferential surface of the photosensitive drum 121.

  Each unit (20) 12Y, 12M, 12C, 12K is connected to a toner cartridge 122, receives the supply of toner from the corresponding toner cartridge 122, and rotates in the clockwise direction in FIG. Only the toner in the developer is supplied toward the peripheral surface 121.

  A charger 123 is provided at the top position of each photosensitive drum 121, and an exposure unit 124 is provided between the charger 123 and the yellow unit 12Y. Further, on the right side of the charger 123 in FIG. 1, a cleaning unit 125 for removing residual toner on the peripheral surface of the photosensitive drum 121 and cleaning it is provided. Each photosensitive drum 121 is uniformly charged at its peripheral surface by the charger 123, and LED light based on image data input from a document image reading device (not shown) is charged from each exposure unit 124. By irradiating the peripheral surface of each photoconductive drum 121, an electrostatic latent image is formed on the peripheral surface of each photoconductive drum 121. By supplying toner from the units 12Y, 12M, 12C, and 12K to the peripheral surface of the photosensitive drum 121 on which the electrostatic latent image is formed, a toner image is formed on the peripheral surface of the photosensitive drum 121. It is like that.

  The transfer unit 13 includes a transfer drum 131 and a transfer roller 132 whose peripheral surface presses and contacts the peripheral surface of the transfer drum 131 via an endless belt 133. The transfer drum 131 is interposed between the paper P and the photosensitive drum 121 and transfers the toner image on the peripheral surface of the photosensitive drum 121 to the paper P. The transfer drum 131 rotates about its axis in the opposite direction (clockwise in FIG. 1) to the photosensitive drum 121 in a state where the peripheral surface is in contact with the peripheral surface of the photosensitive drum 121, thereby the photosensitive drum. The toner image on the peripheral surface 121 is transferred to the peripheral surface of the transfer drum 131.

  The toner image transferred to the peripheral surface of the transfer drum 131 is transferred to the paper P supplied between the transfer drum 131 and the transfer roller 132 via the endless belt 133. The sheet P on which the transfer image is formed is conveyed to the conveyance belt 134 and goes to the fixing unit 14.

  The fixing unit 14 performs a fixing process by heating the transferred image on the paper P transferred by the transfer unit 13. The fixing unit 141 is heated at a predetermined temperature and is positioned below the fixing roller 141. The pressure roller 142 is disposed so that the surfaces face each other. Then, the paper P after the transfer process fed between the fixing roller 141 and the pressure roller 142 by the conveyor belt 134 is heated by the fixing roller 141 heated to a predetermined temperature, thereby forming a transfer image on the paper P. Fixing processing is performed. The sheet P on which the fixing process has been performed is discharged onto a discharge tray 161 through a predetermined conveyance path.

  FIG. 2 is a perspective view showing an embodiment of the developing device 20 according to the present invention, and FIG. 3 is a schematic sectional view in side view. In FIG. 2, 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 is referred to as the right, the -Y direction is referred to as the front, and the + Y direction is referred to as the rear. In the present embodiment, the developing device 20 according to the present invention is applied only to the black unit 12K.

  As shown in FIGS. 2 and 3, the developing device 20 includes a housing 21 in which various members to be described later for stirring and uniformizing the developer are incorporated. As shown in FIG. 3, the housing 21 is formed so as to incline forward toward the front (right side in FIG. 3) and extends in the width direction provided at a substantially central position in the front-rear direction. A toner storage chamber 22 is provided on the rear side through the partition wall 24, and a developer stirring chamber 23 for stirring the developer is provided on the front side.

  The lower edge portion 241 of the partition wall 24 is a free end, and the toner in the toner storage chamber 22 is agitated by the developer between the lower edge portion 241 and the inclined bottom plate 25 inclined upward toward the front of the housing 21. A gap (a communication opening 26 described later) for feeding into the chamber 23 is formed. A sharp ridge 251 extending at the front end of the lower edge 241 of the partition wall 24 and obliquely below the front edge of the partition wall 24 is provided at the substantially center portion in the front-rear direction of the inclined bottom plate 25 and extends over the entire length in the width direction with the tip sharply pointed in a sectional view. It has been. A communication opening 26 is formed between the sharp protrusion 251 and the lower edge 241 of the partition wall 24. The communication opening 26 is the gap for feeding the toner in the toner storage chamber 22 into the developer stirring chamber 23. -ing

  The developing device 20 according to the present invention includes a stirring rod 30 that stirs the toner and is provided in the toner storage chamber 22 of the housing 21 as described above, and the toner that is stirred by the stirring rod 30. 26, a magnet roller (feed roller) 40 that feeds into the developer stirring chamber 23, a double-structure screw feeder 50 that is built in the developer stirring chamber 23 and that uniformly disperses the developer, and the screw feeder 50. A cross-shaped stirring member 60 for further stirring the developer dispersed by the developer, a developing roller 70 to which the developer from the screw feeder 50 is transferred by the cross-shaped stirring member 60, and a developer on the peripheral surface of the developing roller 70. A developer layer thickness regulating roller 80 that regulates the layer thickness is interposed between the toner storage chamber 22 and the developer stirring chamber 23. And (i.e. it is interposed between the magnet roller 40 and the screw feeder 50) and a guide plate 90.

  A toner supply opening 27 that exposes a part of the peripheral surface of the developing roller 70 to the outside is provided at a top portion of the housing 21 that faces the upper portion of the developing roller 70. The toner is separated from the magnetic carrier while being separated from the magnetic carrier. The toner is supplied to the peripheral surface of the photosensitive drum 121 by the rotation of the developing roller 70 through the toner supply opening 27.

  The stirring rod 30 includes a stirring rod shaft 31 laid between a pair of widthwise unillustrated side walls constituting a part of the housing 21, and a plurality of the projecting rods projecting radially from the circumferential surface of the stirring rod shaft 31. And a stirring bar 32 of the book. In the present embodiment, the stirrer 32 is connected to each other at a 45 ° phase along an imaginary spiral formed on the circumferential surface of the stirrer rod shaft 31, thereby effectively rotating the stirrer rod 31. In addition, the developer can be stirred.

  The magnet roller 40 includes a magnet roller shaft 41 installed between the side walls of the housing 21, and a magnet roller body 42 that is externally fitted to the magnet roller shaft 41 so as to be integrally rotatable. Magnetic poles are formed on the peripheral surface of the magnet roller main body 42, whereby the developer is effectively layered on the peripheral surface of the magnet roller main body 42 along with the magnetic carrier being attracted to the magnetic poles. A toner layer is laminated thereon.

  The magnet roller 40 is positioned so that the front (right side in FIG. 3) upper part of the peripheral surface of the magnet roller body 42 faces the communication opening 26, while facing the magnet roller body 42 of the inclined bottom plate 25. In the portion, an arc portion 252 is formed so as to follow a circular locus centering on the axis of the magnet roller shaft 41, and between the inner surface of the arc portion 252 and the peripheral surface of the magnet roller main body 42. A circular arc path 253 having a narrow gap for passing the toner layer on the developer layer is formed.

  In addition, an extremely narrow regulation gap 242 extending in the width direction (direction orthogonal to the paper surface of FIG. 3) is formed between the peripheral surface of the magnet roller main body 42 and the lower edge portion 241 of the partition wall 24, and the magnet roller shaft The developer or toner adsorbed on the peripheral surface of the magnet roller main body 42 rotating counterclockwise around 41 is regulated by the regulation gap 242 so that one of the toner in the toner layer above the developer layer. The part is fed to the developer stirring chamber 23 through the communication opening 26.

  As shown in FIG. 2, the screw feeder 50 includes a feeder shaft 51 extending in the width direction, an inner feeder 52 having a spiral fin 521 integrally formed on a peripheral surface of the feeder shaft 51, and the feeder. A cylindrical outer feeder 53 that is rotatably supported around a shaft 51 is provided.

  The outer feeder 53 includes a pair of widthwise disk walls 531 concentrically fitted to the feeder shaft 51, a cylindrical body 532 concentrically disposed between the pair of disk walls 531, and an outer peripheral surface of the cylindrical body 532. And a spiral strip 533 formed on the surface. Communication holes 534 are formed at appropriate positions on both sides and an intermediate portion in the width direction of the cylindrical body 532 so that the developer can be conveyed into and out of the cylindrical body 532 through these communication holes 534. ing.

  In this embodiment, the spiral fins 521 and the spiral strips 533 are both wound so that the spiral is in a right-handed state (from the top of the feeder shaft 51 and the cylindrical body 532 to the clockwise direction and to advance). And the inner feeder 52 is rotated in the clockwise direction as shown in FIG. 3 in the present embodiment. The outer feeder 53 is rotated counterclockwise while being rotated).

  Accordingly, a part of the developer introduced into the developer stirring chamber 23 through the communication opening 26 passes through the communication hole 534 while being conveyed in one direction by the spiral strip 533 on the peripheral surface of the rotating cylindrical body 532. Then, the introduced developer is conveyed in the reverse direction by the spiral fins 521, and eventually circulated and moved inside and outside the cylindrical body 532 through the communication hole 534. The distribution of the developer in the width direction is made uniform by this circulating conveyance.

  The cross-shaped agitating member 60 delivers the developer uniformly dispersed by the screw feeder 50 toward the developing roller 70, and has an installation shaft 61 installed between a pair of side walls in the width direction of the housing 21. The construction shaft 61 is provided with a cross member 62 which is long in the width direction and is fitted and fixed at the center position. The cross member 62 is formed by four blades 621 that are long in the width direction (direction perpendicular to the paper surface of FIG. 3) projecting from the installation shaft 61 in directions perpendicular to each other. Magnetic poles are respectively formed on the line end surfaces of the vanes 621.

  In the present embodiment, the cross-shaped stirring member 60 is rotated counterclockwise in FIG. 3 around the installation shaft 61. Therefore, the developer that is directed to the cross-shaped stirring member 60 while being guided by the inclined bottom plate 25 by the counterclockwise rotation of the screw feeder 50 is a blade whose magnetic carrier rotates counterclockwise around the installation shaft 61. It is attracted to the magnetic poles of the plate 621 and is efficiently directed to the developing roller 70.

  The developing roller 70 includes a developing roller shaft 71 provided between a pair of side walls of the housing 21 and a developing roller main body 72 that is concentrically and integrally fitted to the developing roller shaft 70. The upper part of the outer peripheral surface of the developing roller main body 72 faces the toner supply opening 27 of the housing 21, thereby facing the peripheral surface of the photosensitive drum 121. The developer reaching the developing roller 70 while being guided to the inclined bottom plate 25 by the rotation of the cross-shaped stirring member 60 is caused by the rotation of the toner in the counterclockwise direction around the developing roller shaft 71 of the developing roller main body 72. The toner is supplied to the peripheral surface of the photosensitive drum 121 rotating counterclockwise through the toner supply opening 27, and a toner image based on the electrostatic latent image is formed on the peripheral surface.

  The developer layer thickness regulating roller 80 regulates the developer layer thickness on the peripheral surface of the developing roller 72 in order to adjust the amount of toner supplied to the photosensitive drum 121, and a pair of side walls of the housing 21. A layer thickness regulating roller shaft 81 provided therebetween, and a layer thickness regulating roller body 82 that is concentrically and integrally fitted to the layer thickness regulating roller shaft 81. The circumferential surface of the layer thickness regulating roller body 82 is in sliding contact with the circumferential surface of the developing roller body 72, and the developer layer on the circumferential surface of the developing roller body 72 is rotated counterclockwise around the layer thickness regulating roller shaft 81. The thickness is adjusted.

  Further, magnetic poles are formed on the peripheral surface of the layer thickness regulating roller main body 82, and by adjusting the developer layer thickness on the peripheral surface of the developing roller main body 72, the toner can be mixed into another developing device or the photosensitive drum. It is possible to prevent the toner image on 121 from being disturbed.

  In the developing device 20 configured as described above, the stirring rod 30, the magnet roller 40, the screw feeder 50, the cross-shaped stirring member 60, the developing roller 70, and the developer layer thickness regulating roller 80 are driven by a drive motor (not shown). By being transmitted through a predetermined gear mechanism, they are driven to rotate while being linked to each other.

  The guide plate 90 that plays an important role in the present invention is arranged on the rear side (left side in FIG. 3) of the sharp protrusion 251 in the inclined bottom plate 25 of the housing 21 in the width direction (direction perpendicular to the plane of FIG. 3). ) Is attached through a double-sided tape, an adhesive or an adhesive. In the guide plate 90, the base end side is fixed to the sharp protrusion 251, and the distal end portion 91 protrudes from the distal end of the sharp protrusion 251 toward the outer peripheral surface of the outer feeder 53, thereby the guide plate 90. A slight developer passage gap 92 through which the developer can pass is formed between the front end portion 91 and the outer peripheral surface of the outer feeder 53.

  The toner pushed toward the contact opening 26 by the restriction gap 242 by the counterclockwise rotation around the magnet roller shaft 41 of the magnet roller body 42 rotates counterclockwise around the feeder shaft 51. The developer is guided to the outer feeder 53, mixed with the developer, and replenished. The developer is conveyed toward the cross-shaped stirring member 60 while being guided by the inclined bottom plate 25 of the housing 21. The toner pushed out toward the communication opening 26 passes through the toner passage gap 92 formed by the tip 91 of the guide plate 90 even if the developer aggregates into a nodule. Therefore, the agglomerated toner is effectively prevented from being fed toward the developing roller 70 via the screw feeder 50 and the cross-shaped stirring member 60 as they are.

  In the present embodiment, the guide plate 90 is a urethane synthetic resin or PET (polyethylene terephthalate) film having a thickness of 0.05 mm to 0.3 mm. Further, the tip 91 of the guide plate 90 has an upward protrusion amount from the sharp protrusion 251 of 1.0 mm to 1.5 mm.

  The urethane-based synthetic resin or PET is adopted as the guide plate 90 because these synthetic resins are mechanically strong and are not easily damaged or worn by the abrasion of the developer. This is because it has suitable elasticity.

  In addition, the guide plate 90 made of such urethane resin or PET preferably has a thickness of 0.05 mm to 0.3 mm. If the guide plate 90 is less than 0.05 mm, durability due to rubbing with the developer may be obtained. This is because it cannot be expected, and if it exceeds 0.3 mm, it becomes too thick and its elasticity becomes small, and the agglomerated toner that is prevented from being fed into the developer stirring chamber 23 is prevented from being fed to the magnet roller 40 side by the elasticity of the guide plate 90. This is because it stays in the vicinity of the tip 91 of the guide plate 90 without being returned. Incidentally, as a result of various tests, it has been found that the thickness of the guide plate 90 is most preferably about 0.15 mm.

  Furthermore, the amount of protrusion of the tip 91 of the guide plate 90 from the sharp protrusion 251 is set to 1.0 mm to 1.5 mm in relation to the thickness dimension as described above, which is less than 1.0 mm. This is because the agglomerated toner is likely to slip through, and conversely, if it exceeds 1.5 mm, the supply of toner to the screw feeder 50 is hindered.

  Hereinafter, the operation of the present invention will be described based on FIGS. 2 and 3 with reference to FIG. 1 as necessary. The toner introduced from the toner cartridge 122 (FIG. 1) into the toner storage chamber 22 of the developing device 20 is agitated by the rotation of the agitation rod 30, and the agglomerated toner is first broken and loosened here. Next, the toner after being agitated by the agitating rod 30 is guided to the magnet roller main body 42 that rotates counterclockwise around the magnet roller shaft 41 in FIG. 3, passes through the arc path 253, and is developed via the communication opening 26. It is directed to the agent stirring chamber 23.

  The toner that has reached the communication opening 26 is cross-stirred while being partially guided over the tip 91 of the guide plate 90 by the outer feeder 53 rotating counterclockwise around the feeder shaft 51. While being directed to the member 60, the remaining portion is introduced into the outer feeder 53 through the communication hole 534 (FIG. 2), and is circulated and conveyed between the inner feeder 52 and the outer feeder 53, thereby developing developer stirring chamber. The distribution in the width direction of the developer in 23 is made uniform. The uniformized developer is also sequentially directed to the cross-shaped stirring member 60 by the rotation of the outer feeder 53.

  The toner fed into the developer agitating chamber 23 from the magnet roller 40 passes through the tip 91 of the guide plate 90 guided by the rotation of the outer feeder 53, even if the aggregated toner is mixed. Due to the portion 91, the aggregated toner cannot pass through the toner passage gap 92. Therefore, it is possible to reliably prevent the occurrence of inconvenience such that the aggregated toner is supplied to the photosensitive drum 121 via the cross-shaped stirring member 60 and the developing roller 70.

  As described in detail above, the developing device 20 according to the present invention includes the toner storage chamber 22 that stores the developer, and the developer that is adjacent to the toner storage chamber 22 via the partition wall 24 and that stirs the developer. The partition wall 24 is provided with a communication opening 26 that allows the toner storage chamber 22 and the developer stirring chamber 23 to communicate with each other. The toner storage chamber 22 faces the communication opening 26 and develops toner. There is provided a magnet roller 40 that feeds into the agent stirring chamber 23, and a predetermined stirring process is applied to the developer fed into the developer stirring chamber 23 by the magnet roller 40 to supply toner to the peripheral surface of the photosensitive drum 121. The base end side is fixed to the inner wall surface of the communication opening 26 at the edge of the communication opening 26 facing the circumferential surface of the magnet roller 40, and the distal end projects through the communication opening 26. The guide plate 90 is provided which protrudes in the developer stirring chamber 23 side state.

  Therefore, when the toner is guided to the peripheral surface by the rotation of the magnet roller 40 and is sent from the toner storage chamber 22 to the developer stirring chamber 23 through the communication opening 26, the guide provided at the edge of the communication opening 26. Since the aggregated toner cannot pass through the toner passage gap 92 formed by the tip of the plate 90, it is possible to effectively prevent the aggregated toner from being introduced into the developer stirring chamber 23.

  Therefore, by introducing the agglomerated toner into the developer agitating chamber 23, toner replenishment unevenness with respect to the photosensitive drum 121 is generated, thereby reliably eliminating the inconvenience that the proper transfer process cannot be performed on the sheet. be able to.

  Further, since the guide plate 90 is formed of polyurethane resin or polyethylene terephthalate, these resins can be easily provided with appropriate elastic force by forming into a plate shape with a predetermined thickness. The agglomerated toner that is prevented from being fed to the developer stirring chamber 23 side is suitable as an elastic material that returns to the magnet roller 40 side. In particular, by setting the shape of the guide plate 90 in advance so that the natural frequency of the guide plate 90 corresponds to the sliding contact state of the developer with respect to the guide plate 90, the guide plate 90 vibrates well when the developer passes therethrough. By this, the effect of dispersing the aggregate of developer aggregated can be further increased.

  Since the thickness dimension of the guide plate 90 made of such polyurethane resin or polyethylene terephthalate is set to 0.05 mm to 0.3 mm, the supply of toner to the screw feeder 50 is not hindered, and only the aggregated toner is used. Can be prevented.

  In the above embodiment, the black unit 12K is applied as the developing device 20 provided with the guide plate 90. However, in the present invention, the developing device 20 provided with the guide plate 90 is the black unit 12K. However, the guide plate 90 may be applied to the cyan unit 12C, the magenta unit 12M, or the yellow unit 12Y.

1 is a side sectional view illustrating an outline of an embodiment of an image forming apparatus to which a developing device according to the present invention is applied. 1 is a perspective view showing an embodiment of a developing device according to the present invention. FIG. 3 is a schematic cross-sectional view of the developing device shown in FIG. 2 in a side view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 11 Apparatus main body 12 Image forming unit 12Y Unit for yellow 12M Unit for magenta 12C Unit for cyan 12K Unit for black 121 Photoconductor drum 122 Toner cartridge 123 Charger 124 Exposure unit 125 Cleaning unit 13 Transfer unit 131 Transfer drum 132 Transfer roller 133 Endless belt 134 Conveyor belt 15 Paper cassette mounting portion 16 Paper discharge portion 161 Paper discharge tray 20 Developing device 21 Housing 22 Toner storage chamber 23 Developer agitation chamber 24 Partition 241 Lower edge 242 Restriction gap 25 Inclined bottom plate 251 Sharp projection Article 252 Arc portion 253 Arc path 26 Connection opening 27 Toner supply opening 30 Stirring rod 31 Stirring rod shaft 32 Stirring rod 40 Magnet roller (feeding roller)
41 Magnet roller shaft 42 Magnet roller body 50 Screw feeder 51 Feeder shaft 52 Inner feeder 521 Spiral fin 53 Outer feeder 531 Disk wall 532 Cylindrical body 533 Spiral strip 534 Communication hole 60 Cross-shaped stirring member 61 Construction shaft 62 Cross member 70 Developing roller 71 Developing roller shaft 72 Developing roller body 80 Developer layer thickness regulating roller 81 Layer thickness regulating roller shaft 82 Layer thickness regulating roller body 90 Guide plate 91 Tip portion 92 Developer passage gap P Paper

Claims (2)

A storage chamber for storing toner and an agitation chamber for agitating a developer in which toner and a carrier mixed in the storage chamber via a partition are mixed, and the partition includes the storage chamber and the agitation A communication opening that communicates with the chamber is provided, and a feeding roller that feeds toner into the stirring chamber facing the communication opening is provided in the storage chamber. The toner that is fed into the stirring chamber by the feeding roller has a predetermined amount. In a developing device configured to supply toner to the peripheral surface of the photosensitive drum by performing a stirring process,
At the edge of the communication opening facing the peripheral surface of the feed roller, a guide plate is provided with a proximal end fixed to the inner wall surface of the communication opening and a distal end protruding through the communication opening with the distal end passing through the communication opening. A developing device.   The developing device according to claim 1, wherein the guide plate is made of polyurethane or polyethylene terephthalate.