JP6468221B2 - Developing device, image forming apparatus - Google Patents

Description

  The present invention relates to a developing device and an image forming apparatus.

  In general, an electrophotographic developing device includes a developer container, a cylindrical developer carrier, a magnet provided in a hollow portion of the developer carrier, and a stirring unit for stirring the developer. And a layer thickness limiting portion that limits the layer thickness of the developer on the developer carrying member.

  The stirring portion is a screw feeder type member having a shaft portion and a blade portion projecting outward from the shaft portion spirally. The developer carrier is referred to as a magnetic roller or a magnetic sleeve.

  It is known that uneven density of the developer may be formed in a streak shape along the blade portion of the stirring unit on the surface of the developer carrying member. In particular, when the developer contains a toner of a type having a low melting point, the density unevenness due to the stirring portion is likely to occur.

  Further, it is known that a regulating plate facing the outer peripheral surface of the developer carrying member is provided upstream of the layer thickness regulating portion in the rotation direction of the developer carrying member (for example, Patent Document 1). reference).

  The restriction plate compresses the developer by narrowing a passage of the developer carried on the developer carrying member. Thereby, the density unevenness of the developer on the outer peripheral surface of the developer carrier is reduced or eliminated.

JP 2013-64781 A

  By the way, the toner having a low melting point is easily deteriorated by compression. Therefore, it is desirable that the uneven density of the developer on the outer peripheral surface of the developer carrying member can be reduced or eliminated without applying excessive pressure to the developer.

  An object of the present invention is to develop that can alleviate or eliminate the uneven density of the developer due to the screw feeder type stirring portion on the outer peripheral surface of the developer carrier without applying excessive pressure to the developer. An apparatus and an image forming apparatus including the same are provided.

  A developing device according to one aspect of the present invention includes a storage unit, a developer carrier, a stirring unit, a layer thickness limiting unit, a guide unit, and a flexible member. The accommodating portion is a portion for accommodating a developer containing toner. The stirring unit is a member that has a blade portion projecting outward in a spiral shape and stirs the developer by rotating in the housing portion. The developer carrier includes a magnet, faces the agitation unit with a first gap above the agitation unit in the housing unit, and rotates with the developer carried on an outer peripheral surface. It is a cylindrical member. The layer thickness limiting portion is opposed to the developer carrying body with a second gap at a position downstream of the stirring portion in the rotation direction of the developer carrying body. The layer thickness limiting unit limits the layer thickness of the developer carried on the developer carrying member. The guide portion is provided between the stirring portion and the layer thickness limiting portion. The flexible member is a film-like member attached to the guide portion. The guide part has a guide surface and a drop passage part. The guide surface is a surface that faces the developer carrying member obliquely from below with a third gap forming a passage of the developer toward the second gap. The drop passage portion communicates with a first opening formed in the guide surface and a second opening provided below the first opening, and passes the developer passage falling from the third gap. It is a part to make. The flexible member is attached in a cantilevered manner to the edge of the first opening in the guide portion, and is formed so as to project to the first opening. The flexible member is deformed by receiving pressure from the developer passing through the third gap and bending to form a shape that closes the first opening and enters the fall passage portion.

  An image forming apparatus according to another aspect of the present invention includes an image carrier, the developing device, a transfer device, and a fixing device. The image carrier is a member on which an electrostatic latent image is formed. The developing device develops the electrostatic latent image on the surface of the image carrier into a toner image. The transfer device transfers the toner image onto a sheet. The fixing device heats the toner image transferred to the sheet.

  According to the present invention, development that can alleviate or eliminate the developer density unevenness caused by the screw feeder type stirring portion on the outer peripheral surface of the developer carrying member without applying excessive pressure to the developer. It becomes possible to provide an apparatus and an image forming apparatus including the apparatus.

FIG. 1 is a configuration diagram of an image forming apparatus including a developing device according to the first embodiment. FIG. 2 is a cross-sectional view of the developing device according to the first embodiment. FIG. 3 is a plan view of a second stirring screw in the developing device according to the first embodiment. FIG. 4 is a cross-sectional view of the guide portion and its periphery in the developing device according to the first embodiment. FIG. 5 is a front view of the first guide surface and the flexible member in the developing device according to the first embodiment. FIG. 6 is a cross-sectional view of the first guide portion and its periphery when the developer falls along the drop passage portion in the developing device according to the first embodiment. FIG. 7 is a cross-sectional view of the first guide portion and its periphery in the developing device according to the second embodiment. FIG. 8 is a front view of the first guide surface and the flexible member in the developing device according to the third embodiment. FIG. 9 is a front view of the first guide surface and the flexible member in the developing device according to the third embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the following embodiment is an example which actualized this invention, Comprising: It does not have the character which limits the technical scope of this invention.

First Embodiment: Configuration of Image Forming Apparatus 10
First, the configuration of the image forming apparatus 10 including the developing device 43 according to the first embodiment will be described with reference to FIG.

  The image forming apparatus 10 is an apparatus that forms an image on a sheet by using an electrophotographic method using the developer 9. The sheet is a sheet-like image forming medium such as paper and an envelope. Developer 9 is a two-component developer including toner 9a and carrier 9b. The carrier 9b is a granular material having magnetism.

  The image forming apparatus 10 includes a sheet supply unit 2, a sheet conveying unit 3, an image forming unit 40, a toner supply unit 400, and the like. The image forming unit 40 includes an image forming unit 4, an optical scanning unit 46, a fixing device 49, and the like. The image forming unit 40 executes a printing process for forming an image on the sheet.

  In the sheet supply unit 2, the sheet delivery unit 22 sends out the sheets one by one from the sheet cassette 21 that stores a plurality of the sheets to the conveyance path 30. Further, the sheet conveyance unit 3 conveys the sheet along the conveyance path 30, and discharges the sheet on which the image is formed from the conveyance path 30 onto the discharge tray 101.

  The image forming unit 4 performs development processing and primary transfer processing using a powdery developer 9. An image forming apparatus 10 shown in FIG. 1 is a tandem image forming apparatus and a color printer. Therefore, the image forming apparatus 10 includes a plurality of image forming units 4 corresponding to each color of cyan, magenta, yellow, and black, an intermediate transfer belt 47, a secondary transfer device 48, and a secondary cleaning device 470.

  Each of the image forming units 4 includes a photoreceptor 41, a charging device 42, a developing device 43, a primary transfer device 44, a primary cleaning device 45, and the like.

  In each image forming unit 4, the drum-shaped photoconductor 41 rotates, and the charging device 42 charges the surface of the photoconductor 41 uniformly. The optical scanning unit 46 writes an electrostatic latent image on the surface of the photoconductor 41 by scanning with laser light. The photoreceptor 41 is an example of an image carrier on which the electrostatic latent image is formed.

  The developing device 43 uses the two-component developer 9 to develop the electrostatic latent image on the photoreceptor 41 as an image of the toner 9a. The toner replenishing unit 400 is provided for each color of the toner 9a, and replenishes the toner 9a to each developing device 43.

  The primary transfer device 44 transfers the image of the toner 9 a on the surface of the photoreceptor 41 to the intermediate transfer belt 47. The primary cleaning device 45 removes the toner 9 a remaining on the surface of the photoreceptor 41.

  The secondary transfer device 48 transfers the toner image formed on the intermediate transfer belt 47 to the sheet in the conveyance path 30. The secondary cleaning device 470 removes the toner 9a remaining on the intermediate transfer belt 47.

  The primary transfer device 44, the intermediate transfer belt 47, and the secondary transfer device 48 constitute a transfer device that transfers the toner image on the photoreceptor 41 to the sheet.

  The fixing device 49 heats the toner image transferred to the sheet and fixes the toner image on the sheet. The fixing device 49 includes a fixing roller that rotates in contact with the toner image formed on the sheet, and a heater that heats the fixing roller.

  It is conceivable that a low melting point type toner having a melting point of less than 150 ° C. is adopted as the toner 9 a of the developer 9. In this case, it is conceivable that the set temperature of the fixing roller heating control by the heater in the fixing device 49 is 150 ° C. or less. Thereby, the power consumption of the fixing device 49 can be suppressed.

[Configuration of Developing Device 43]
The developing device 43 shown in FIG. 2 is a so-called interactive touch-down developing device. The developing device 43 includes a storage unit 4300, a developing roller 430, a magnetic roller 431, a magnet 432, a first stirring screw 433, a second stirring screw 434, a blade 435, a guide unit 436, and the like. The magnet 432 is provided in the hollow part of the cylindrical magnetic roller 431.

  The developing roller 430, the magnetic roller 431, the first stirring screw 433, and the second stirring screw 434 rotate in the storage unit 4300 that stores the developer 9. The first stirring screw 433 and the second stirring screw 434 circulate and convey the developer 9 in the storage unit 4300 while stirring. The toner 9a is charged by being stirred.

  As shown in FIG. 3, the second stirring screw 434 is a screw feeder type stirring unit having a shaft part 434 a and a spiral blade part 434 b. The second stirring screw 434 rotates around the shaft portion 434a. The blade portion 434b is formed to project outward from the shaft portion 434a in a spiral shape. The first stirring screw 433 also has the same structure as the second stirring screw 434.

  The second stirring screw 434 rotates at a position facing the magnetic roller 431 across the first gap G1. The second agitation screw 434 is an example of an agitation unit that agitates the developer 9 by rotating in the accommodation unit 4300.

  The second stirring screw 434 conveys the developer 9 to the first gap G1 while stirring. As a result, the developer 9 is supplied to the magnetic roller 431.

  The magnetic roller 431 enclosing the magnet 432 is opposed to the second stirring screw 434 with a first gap G1 above the second stirring screw 434 in the housing portion 4300.

  The magnetic roller 431 is a cylindrical member that rotates in a predetermined positive rotation direction R0 and carries the two-component developer 9 on its outer peripheral surface and rotates. The magnetic roller 431 supplies the toner 9 a of the carried developer 9 to the developing roller 430. The magnetic roller 431 is an example of a developer carrier.

  The blade 435 is opposed to the magnetic roller 431 with a second gap G2 at a position downstream of the second stirring screw 434 in the forward rotation direction R0 of the magnetic roller 431. The blade 435 is provided at a position between the developing roller 430 and the second stirring screw 434 around the magnetic roller 431.

  The blade 435 limits the layer thickness of the developer 9 carried by the magnetic roller 431. The layer of the developer 9 on the outer peripheral surface of the magnetic roller 431 has a thickness substantially corresponding to the height of the second gap G2 by passing through the second gap G2. The blade 435 is an example of a layer thickness limiting portion.

  The magnet 432 includes a first magnetic pole part 432a, a second magnetic pole part 432b adjacent to the first magnetic pole part 432a on the downstream side in the positive rotation direction R0, and a downstream side of the second magnetic pole part 432b in the positive rotation direction R0. It includes an adjacent third magnetic pole portion 432c and an adjacent fourth magnetic pole portion 432d downstream of the third magnetic pole portion 432c in the forward rotation direction R0.

  The magnetic roller 431 carries the developer 9 by the magnetic force of the magnet 432 included therein. That is, the first magnetic pole portion 432a magnetically attracts the developer 9, and the developer 9 is pumped from the periphery of the second stirring screw 434 onto the outer peripheral surface of the magnetic roller 431 by the magnetic force of the first magnetic pole portion 432a.

  The first magnetic pole portion 432a is located in a range upstream of the blade 435 in the forward rotation direction R0 of the magnetic roller 431. A part of the first magnetic pole part 432a faces the second stirring screw 434 via the first gap G1.

  The second magnetic pole portion 432b is provided in a range upstream of the portion of the magnetic roller 431 that faces the developing roller 430 in the forward rotation direction R0 of the magnetic roller 431. A part of the second magnetic pole part 432b faces the blade 435 through the magnetic roller 431. The magnetic pole of the second magnetic pole part 432b is different from the magnetic pole of the first magnetic pole part 432a.

  The developing roller 430 rotates while carrying the toner 9a supplied from the magnetic roller 431 on the outer peripheral surface. Further, the developing roller 430 supplies the toner 9 a to the portion of the electrostatic latent image on the surface of the photoreceptor 41. As a result, the developing roller 430 develops the electrostatic latent image on the surface of the photoreceptor 41 into the toner image.

  The third magnetic pole portion 432 c faces the developing roller 430 with the magnetic roller 431 interposed therebetween. The magnetic pole of the third magnetic pole part 432c is the same as the magnetic pole of the first magnetic pole part 432a. In addition, the magnetic pole of the third magnetic pole portion 432c is different from the magnetic pole of the first magnetic pole portion 432a.

  The plurality of carriers 9 b on the magnetic roller 431 form a magnetic brush by the magnetic field of the magnet 432. The magnetic brush contacts the outer peripheral surface of the developing roller 430. At that time, the toner 9 a adhering to the carrier 9 b moves from the magnetic roller 431 to the developing roller 430.

  The toner 9 a moves from the developing roller 430 to the photosensitive member 41 in a portion of the layer of the toner 9 a carried on the developing roller 430 that faces the electrostatic latent image of the photosensitive member 41. The toner 9a remaining on the developing roller 430 without moving to the photoreceptor 41 is collected in the storage unit 4300.

  By the way, it is known that the density unevenness of the developer 9 may be formed in a streak shape along the blade portion 434b of the second stirring screw 434 on the outer peripheral surface of the magnetic roller 431. The blade portion 434 b of the second stirring screw 434 causes the distribution of the layer thickness of the developer 9 in the axial direction of the magnetic roller 431, thereby causing uneven density of the developer 9.

  Further, in the conventional apparatus, it is known that a restriction plate facing the outer peripheral surface of the magnetic roller 431 is provided upstream of the blade 435 in the normal rotation direction R0 of the magnetic roller 431.

  The restriction plate compresses the developer 9 carried on the magnetic roller 431. Thereby, the density unevenness of the developer 9 on the outer peripheral surface of the magnetic roller 431 is alleviated or eliminated.

  The type of toner 9a having a low melting point is easily deteriorated by being compressed. Therefore, it is desirable that the uneven density of the developer 9 on the outer peripheral surface of the magnetic roller 431 can be reduced or eliminated without applying excessive pressure to the developer 9.

  The developing device 43 has a structure that can reduce or eliminate the uneven density of the developer 9 due to the second stirring screw 434 on the outer peripheral surface of the magnetic roller 431 without applying excessive pressure to the developer 9. Prepare. The structure will be described below.

[Guide 436]
The guide portion 436 is a member disposed between the second stirring screw 434 and the blade 435. In the example shown in FIG. 2, the guide portion 436 is attached to the surface of the blade 435 on the second stirring screw 434 side.

  The guide unit 436 includes a first guide surface 436 a that faces the magnetic roller 431 and a second guide surface 436 b that faces the second stirring screw 434. Further, the guide part 436 has a drop passage part 436c. A flexible member 437 is attached to the guide portion 436.

  The first guide surface 436a faces the magnetic roller 431 from below obliquely across the third gap G3. The third gap G3 forms a passage of the developer 9 from the first gap G1 to the second gap G2. The first guide surface 436a guides the developer 9 that has moved from the periphery of the second stirring screw 434 to the outer peripheral surface of the magnetic roller 431 in the first gap G1 toward the second gap G2.

  The third gap G3 is gradually narrowed from the second stirring screw 434 side toward the second gap G2 side.

  The second guide surface 436b faces the second stirring screw 434 with a fourth gap G4 therebetween. The fourth gap G4 forms a passage for the developer 9 toward the first gap G1. The third gap G3 is gradually narrowed from the first gap G1 side toward the second gap G2 side. That is, the first guide surface 436a gradually narrows the path of the developer 9 that is carried by the magnetic roller 431 and travels toward the second gap G2, and guides the developer 9 to the first gap G1.

  The developer transport direction D1 shown in FIGS. 4 and 5 is a direction perpendicular to the longitudinal direction of the rotation axis of the magnetic roller 431 and viewed toward the blade 435 when viewed from the front of the first guide surface 436a. A portion of the outer peripheral surface of the magnetic roller 431 that rotates in the normal rotation direction R0 that faces the first guide surface 436a moves in the developer transport direction D1.

  The drop passage portion 436c is a hollow portion that forms a passage of the developer 9 that falls from the third gap G3. The drop passage portion 436c communicates with a first opening 436d formed in the first guide surface 436a and a second opening 436e provided below the first opening 436d. The second opening 436e is formed in the second guide surface 436b.

  As shown in FIG. 5, the first guide surface 436 a and the first opening 436 d are formed in a range from a position near one end in the rotation axis direction to a position near the other end of the magnetic roller 431. Yes. In FIG. 5, the magnetic roller 431 existing in front of the first guide surface 436a is indicated by an imaginary line.

  Similarly, the second guide surface 436b and the second opening 436e are also formed in a range from a position near one end in the rotation axis direction to a position near the other end of the magnetic roller 431. Accordingly, the drop passage portion 436c is also formed in a range from a position near one end in the rotation axis direction of the magnetic roller 431 to a position near the other end.

  The flexible member 437 is a film-like member. For example, the flexible member 437 may be a synthetic resin film member mainly composed of PET (polyethylene terephthalate).

  As shown in FIGS. 4 and 5, the flexible member 437 is attached to the edge portion of the first opening 436 d in the guide portion 436 in a cantilever state. A portion of the flexible member 437 closer to the tip than the portion fixed to the guide portion 436 is formed to project to the first opening 436d. The flexible member 437 closes the first opening 436d in a natural state.

  In the example shown in FIGS. 2 and 3, the flexible member 437 is attached in a cantilevered manner to a portion of the edge of the first opening 436 d of the guide portion 436 on the upstream side in the normal rotation direction R 0 of the magnetic roller 431. ing. That is, the portion of the guide portion 436 where a part of the flexible member 437 is fixed is a portion on the upstream side in the developer transport direction D1 with respect to the first opening 436d. In this case, the tip of the flexible member 437 can be prevented from turning up toward the third gap G3 due to the pressure of the developer 9 moving through the third gap G3.

  When the developer 9 passes through the third gap G3 in a moderately compressed state, the flexible member 437 maintains a shape that closes the first opening 436d. In this case, the developer 9 moving through the third gap G3 hardly enters the fall passage portion 436c.

  On the other hand, when the developer 9 passing through the third gap G3 is compressed more than necessary, a large pressure is applied from the developer 9 to the flexible member 437.

  The flexible member 437 is bent by receiving an external force of a certain level or more from the third gap G3 side, and the portion protruding to the first opening 436d is displaced into the drop passage portion 436c. The external force from the third gap G3 side is a force received from the developer 9 filled in the third gap G3.

  That is, the flexible member 437 receives the pressure of a certain level or more from the developer 9 passing through the third gap G3 and bends, thereby closing the first opening 436d as shown in FIG. It deform | transforms into the shape which approached in the fall channel | path part 436c as shown by these.

  When the flexible member 437 is deformed into a shape that has entered the drop passage portion 436c, a gap that communicates from the third gap G3 into the drop passage portion 436c is formed in the portion of the first opening 436d. Thereby, a part of the developer 9 that passes through the third gap G3 falls from the first opening 436d through the drop passage portion 436c. As a result, the pressure applied to the developer 9 passing through the third gap G3 is relieved.

  For example, it is conceivable that the width of the first opening 436d in the developer transport direction D1 is about 1 millimeter to 2 millimeters. In this case, it is conceivable that the thickness of the synthetic resin flexible member 437 mainly composed of PET is about 0.05 to 0.10 mm. Thereby, the pressure of the developer 9 passing through the third gap G3 is maintained moderately.

  The developer 9 that has dropped through the drop passage portion 436c is collected in a region near the bottom of the storage portion 4300 around the second stirring screw 434.

  In the developing device 43, the pressure applied to the developer 9 passing through the third gap G3 is appropriately maintained. Thereby, the density unevenness of the developer 9 due to the second stirring screw 434 on the outer peripheral surface of the magnetic roller 431 is eliminated or at least alleviated without applying excessive pressure to the developer 9.

[Second Embodiment]
Next, a developing device 43A according to a second embodiment applicable to the image forming apparatus 10 will be described with reference to FIG. 7, the same components as those shown in FIGS. 1 to 5 are given the same reference numerals.

  The developing device 43A differs from the developing device 43 in that it includes two flexible members 437a and 437b.

  The first flexible member 437a, which is one of the two flexible members 437a and 437b, is located at the upstream portion of the edge of the first opening 436d of the guide portion 436 in the forward rotation direction R0 of the magnetic roller 431. It is attached in a cantilevered state. This is the same as the flexible member 437 of the developing device 43.

  The second flexible member 437b, which is the other of the two flexible members 437a and 437b, is located on the downstream side of the magnetic roller 431 in the forward rotation direction R0 at the edge of the first opening 436d of the guide portion 436. It is attached in a cantilevered state.

  And the 1st flexible member 437a and the 2nd flexible member 437b are attached to the guide part 436 in the state which the part which protruded to the 1st opening 436d mutually overlaps.

  In the example shown in FIG. 7, the tip of the first flexible member 437a overlaps the third gap G3 side of the second flexible member 437b. Accordingly, the distal end portion of the second flexible member 437b overlaps the drop passage portion 436c side of the first flexible member 437a.

  The two flexible members 437a and 437b are bent by receiving a pressure equal to or higher than a certain level from the developer 9 passing through the third gap G3, so that each of the flexible members 437a and 437b closes the first opening 436d into the fall passage portion 436c. Deform to the shape that entered.

  When the two flexible members 437a and 437b are deformed, a gap is formed between the two flexible members 437a and 437b. Thereby, a part of the developer 9 that passes through the third gap G3 falls from the first opening 436d through the drop passage portion 436c. As a result, the pressure applied to the developer 9 passing through the third gap G3 is relieved.

  When the developing device 43A is employed, the same effect as that obtained when the developing device 43 is employed can be obtained. Further, in the developing device 43A, in addition to the material and thickness of the two flexible members 437a and 437b, the overlapping width of the two flexible members 437a and 437b is also equal to the two flexible members 437a and 437b. This is a parameter for adjusting the pressure when a gap is formed between the two.

  Therefore, when the developing device 43A is employed, the degree of freedom in designing the adjustment parameter for maintaining the pressure of the developer 9 passing through the third gap G3 is increased, and the adjustment is facilitated.

[Third Embodiment]
Next, a developing device 43B according to a third embodiment applicable to the image forming apparatus 10 will be described with reference to FIG. In FIG. 8, the same components as those shown in FIGS. 1 to 5 are given the same reference numerals.

  The developing device 43B is different from the developing device 43 in that a flexible member 437x having a slit 437c formed in part is employed instead of the flexible member 437.

  The slit 437c is formed in a portion near the both ends in the rotation axis direction of the magnetic roller 431 in a portion protruding to the first opening 436d of the flexible member 437x. In the example of FIG. 8, the plurality of slits 437 c are formed at intervals in the rotation axis direction of the magnetic roller 431. The slit 437c is not formed in the central portion of the flexible member 437x in the rotation axis direction of the magnetic roller 431.

  The portion near the both ends of the flexible member 437x is more flexible than the central portion because the slit 437c is formed.

  In general, in the third gap G3, the pressure applied to the developer 9 passing through a region near both ends of the magnetic roller 431 in the rotation axis direction is smaller than the pressure applied to the developer 9 passing through other regions.

  If the developing device 43B is employed, the pressure of the developer 9 that passes through the third gap G3 is made uniform in the direction of the rotation axis of the magnetic roller 431 and is appropriately maintained.

[Fourth Embodiment]
Next, a developing device 43C according to a fourth embodiment applicable to the image forming apparatus 10 will be described with reference to FIG. 9, the same components as those shown in FIGS. 1 to 5 are given the same reference numerals.

  The developing device 43C is different from the developing device 43 in that a plurality of convex portions 438 are formed on the first guide surface 436a.

  The plurality of convex portions 438 are formed in a region on the first guide surface 436a extending from a position near one end in the longitudinal direction of the rotation axis of the magnetic roller 431 to a position near the other end.

  In the example shown in FIG. 9, a plurality of convex portions 438 arranged in a staggered manner are formed on the first guide surface 436 a of the guide portion 436. For example, it is conceivable that the heights of the tops of the plurality of convex portions 438 are the same.

  In the example shown in FIG. 9, each of the convex portions 438 is cylindrical. It is also conceivable that each of the convex portions 438 has a polygonal cross-sectional shape.

  Each of the plurality of convex portions 438 forms a step along a direction intersecting the developer transport direction D1 in most of the outer periphery. Therefore, when the developer 9 moves through the third gap G3, the density distribution of the developer 9 is made uniform in the direction in which the plurality of convex portions 438 make it uniform. Thereby, the density unevenness of the developer 9 is further alleviated.

[Application example]
In the developing device 43A, the overlapping width of the portion of the two flexible members 437a and 437b that protrudes to the first opening 436d near the both ends in the rotation axis direction of the magnetic roller 431 is larger than the overlapping width of the central portion. It can be considered small. Also in this case, the portions near the both ends of the two flexible members 437a and 437b are more flexible than the central portion.

  It is also conceivable that the flexible member 437x in which the slit 437c is formed is applied to the developing devices 43A and 43C.

  In addition, a plurality of convex portions 438 in the developing device 43C may be applied to the developing device 43A.

  In the developing device 43C, the plurality of convex portions 438 form irregularities on the first guide surface 436a. On the other hand, a plurality of recesses having the same contour shape as the plurality of projections 438 when viewed from the front of the first guide surface 436a are formed on the first guide surface 436a instead of the plurality of projections 438. Conceivable.

  Furthermore, in the developing devices 43, 43A, 43B, and 43C, it is conceivable that the plurality of convex portions 438 or the plurality of concave portions are formed on both the first guide surface 436a and the second guide surface 436b.

  The developing device and the image forming apparatus according to the present invention can be freely combined within the scope of the invention described in each claim, or can be appropriately combined with the above-described embodiments and application examples. It is also possible to configure by deforming or omitting a part.

2: Sheet feeding unit 3: Sheet conveying unit 4: Image forming unit 9: Developer 9a: Toner 9b: Carrier 10: Image forming apparatus 21: Sheet cassette 22: Sheet feeding unit 30: Conveying path 40: Image forming unit 41: Photoconductor 42: Charging device 43, 43A to 43C: Developing device 44: Primary transfer device 45: Primary cleaning device 46: Optical scanning unit 47: Intermediate transfer belt 48: Secondary transfer device 49: Fixing device 101: Discharge tray 400: Toner replenishing section 430: developing roller 431: magnetic roller (developer carrier)
432: Magnet 432a: First magnetic pole portion 432b: Second magnetic pole portion 432c: Third magnetic pole portion 432d: Fourth magnetic pole portion 433: First stirring screw 434: Second stirring screw (stirring portion)
434a: shaft portion 434b: blade portion 435: blade (layer thickness limiting portion)
436: Guide portion 436a: First guide surface (guide surface)
436b: second guide surface 436c: drop passage portion 436d: first opening 436e: second openings 437, 437x: flexible member 437a: first flexible member 437b: second flexible member 437c: slit 438: Convex part 470: secondary cleaning device 4300: storage part D1: developer transport direction G1: first gap G2: second gap G3: third gap G4: fourth gap R0: forward rotation direction

Claims (9)

An accommodating portion for accommodating a developer containing toner;
A stirring portion that has a blade portion that protrudes outward in a spiral shape and stirs the developer by rotating in the housing portion;
A cylindrical developer carrying member that includes a magnet, opposes the stirring unit above the stirring unit in the housing unit with a first gap therebetween, and rotates while supporting the developer on an outer peripheral surface. When,
The developer carrier is opposed to the developer carrier with a second gap at a position on the downstream side in the rotation direction of the developer carrier with respect to the stirring unit, and the developer carrier is carried on the developer carrier. A layer thickness limiting portion for limiting the layer thickness of the developer;
A guide section provided between the stirring section and the layer thickness limiting section;
A film-like flexible member attached to the guide part,
The guide part is
A guide surface facing the developer carrying member obliquely from below with a third gap forming a path of the developer toward the second gap;
A drop passage portion that communicates with a first opening formed in the guide surface and a second opening provided below the first opening, and forms a passage of the developer falling from the third gap; Have
The developer is attached to an edge portion of the first opening in the guide portion in a cantilever state, and is formed to protrude to the first opening and passes through the third gap. Deformed from a shape that closes the first opening by bending under pressure from the shape that has entered the fall passage portion ,
At the edge portion of the first opening of the guide portion, the developer carrier is attached to the upstream portion and the downstream portion in the rotation direction in a cantilever state, and the portions protruding to the first opening are mutually connected. A developing device comprising two flexible members overlapping each other . An accommodating portion for accommodating a developer containing toner;
A stirring portion that has a blade portion that protrudes outward in a spiral shape and stirs the developer by rotating in the housing portion;
A cylindrical developer carrying member that includes a magnet, opposes the stirring unit above the stirring unit in the housing unit with a first gap therebetween, and rotates while supporting the developer on an outer peripheral surface. When,
The developer carrier is opposed to the developer carrier with a second gap at a position on the downstream side in the rotation direction of the developer carrier with respect to the stirring unit, and the developer carrier is carried on the developer carrier. A layer thickness limiting portion for limiting the layer thickness of the developer;
A guide section provided between the stirring section and the layer thickness limiting section;
A film-like flexible member attached to the guide part,
The guide part is
A guide surface facing the developer carrying member obliquely from below with a third gap forming a path of the developer toward the second gap;
A drop passage portion that communicates with a first opening formed in the guide surface and a second opening provided below the first opening, and forms a passage of the developer falling from the third gap; Have
The developer is attached to an edge portion of the first opening in the guide portion in a cantilever state, and is formed to protrude to the first opening and passes through the third gap. Deformed from a shape that closes the first opening by bending under pressure from the shape that has entered the fall passage portion,
Wherein in said projecting portion to the first opening of the flexible member, near both ends of the portion in the rotation axis direction of the developer carrying member has a high flexibility than the central portion, the current image device. The developing device according to claim 2 , wherein a slit is formed in a portion of the flexible member that protrudes to the first opening and near the both ends, and no slit is formed in the central portion. 4. The flexible member is attached in a cantilevered manner to a portion of the edge of the first opening of the guide portion on the upstream side in the rotation direction of the developer carrier. 5. The developing device according to 1. At the edge portion of the first opening of the guide portion, the developer carrier is attached to the upstream portion and the downstream portion in the rotation direction in a cantilever state, and the portions protruding to the first opening are mutually connected. The developing device according to claim 2 , comprising two flexible members overlapping each other.   The developing device according to claim 1, wherein a plurality of convex portions or a plurality of concave portions are formed on the guide surface.   The developing device according to claim 1, wherein the flexible member is a synthetic resin member containing polyethylene terephthalate as a main component. An image carrier on which an electrostatic latent image is formed on the surface;
The developing device according to any one of claims 1 to 7, wherein the electrostatic latent image on the surface of the image carrier is developed into a toner image.
A transfer device for transferring the toner image to a sheet;
An image forming apparatus comprising: a fixing device that heats the toner image transferred to the sheet.   The image forming apparatus according to claim 8, wherein a set temperature of heating control in the fixing device is 150 ° C. or less.

Images