Developing apparatus and image forming apparatus

Abstract

To provide a developing device that can prevent toner from accumulating below a supply roller and a toner scraping body in a housing, and provide an image forming apparatus.SOLUTION: A developing device 3 comprises: a developing roller 31; a supply roller 32; a housing 40 that has a toner storage chamber 41 and a developing chamber 43; a toner scraping body 33 that is arranged in the developing chamber 43 and in contact with the supply roller 32 to scrape off a toner T1 attached to a surface of the supply roller 32; and an agitator 35 that rotates in the toner storage chamber 41 to agitate the toner T1. The toner storage chamber 41 and the developing chamber 43 are arranged side by side in a fore-and-aft direction. The housing 40 has a rib 50 that is arranged between the toner storage chamber 41 and the toner scraping body 33 in the fore-and-aft direction and can be in contact with a leading end part 35A of the agitator 35, the rib 50 provided above a lower end 33D of the toner scraping body 33 to be separated from the leading end part 35A of the rotating agitator 35.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a developing device and an image forming apparatus.

Background Art

[0002] An example of a conventional developing device is disclosed in FIG. 3 of Patent Document 1. This developing device is provided in an electrophotographic printer, which is an example of an image forming apparatus, together with a photosensitive drum.

[0003] This developing device includes a toner carrier as a developing roller, a sponge roller as a supply roller, a toner cartridge as a housing, and a toner stirring shaft as an agitator.

[0004] The sponge roller supplies toner to the toner carrier. The toner cartridge has a toner storage chamber for storing toner and a developing chamber in which the toner carrier and the sponge roller are disposed. The toner stirring shaft rotates in the toner storage chamber to stir the toner.

[0005] As shown in FIG. 1 of Patent Document 1, the developing device further includes an auxiliary roller as a toner scraping body. The auxiliary roller abuts on the sponge roller and scrapes off the toner adhering to the surface of the sponge roller.

[0006] With such a configuration, the developing device supplies toner to the photosensitive drum. At this time, the developing device stabilizes the amount of toner supplied by the sponge roller to the toner carrier by scraping off excess toner from the sponge roller by the auxiliary roller.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] By the way, in the conventional developing apparatus described above, the toner scraped off the sponge roller by the auxiliary roller flows towards the toner storage chamber due to the inertial force of the sponge roller's rotation and tries to return to the toner storage chamber.

[0009] However, the toner flow attempting to return to the toner storage chamber is likely to collide with the toner flow that is agitated by the toner agitation shaft and moving from the toner storage chamber towards the developing chamber, thus easily hindering its return to the toner storage chamber. As a result, this developing device may have difficulty preventing toner from accumulating below the sponge roller and auxiliary roller within the toner cartridge.

[0010] The present invention has been made in view of the above-mentioned conventional circumstances, and aims to provide a developing apparatus and an image forming apparatus that can suppress the accumulation of toner below the supply roller and toner scraping body inside the housing. [Means for solving the problem]

[0011] The developing apparatus of the present invention comprises a developing roller and A supply roller that supplies toner to the developing roller, A housing having a toner storage chamber for storing toner, and a developing chamber in which the developing roller and the supply roller are arranged, A toner scraping body is placed in the developing chamber and contacts the supply roller to scrape off toner adhering to the surface of the supply roller, The toner storage chamber includes an agitator that rotates within the toner storage chamber to agitate the toner, The toner storage chamber and the developing chamber are arranged in the front-to-back direction. The housing is characterized by having a rib positioned between the toner storage chamber and the toner scraping body in the front-rear direction, which is capable of contacting the tip of the agitator, and which is positioned so as to be separated from the tip of the rotating agitator at a point above the lower end of the toner scraping body.

[0012] In the developing apparatus of the present invention, the toner scraped off by the toner scraping body flows toward the toner storage chamber due to the inertial force of the rotation of the supply roller and attempts to return to the toner storage chamber.

[0013] In this process, the tip of the rotating agitator moves while being constrained by the rib it is in contact with, and is no longer constrained by the rib when the rib separates from the tip above the lower end of the toner scraping body.

[0014] As a result, the toner flow from the toner storage chamber towards the developing chamber, agitated by the agitator, is more likely to occur above the upper end of the rib. In other words, the tip of the agitator is less likely to obstruct the toner flow returning to the toner storage chamber, at least below the lower end of the toner scraping body.

[0015] Therefore, the developing apparatus of the present invention can suppress the accumulation of toner below the supply roller and toner scraping body within the housing. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic cross-sectional view of an image forming apparatus equipped with the developing device of the embodiment. [Figure 2] This is a schematic cross-sectional view of the developing apparatus of the embodiment. [Figure 3] This is a partial top view showing multiple ribs and other features as seen from the Z direction indicated by the arrow in Figure 2. [Figure 4] This is a schematic cross-sectional view of a developing apparatus according to an embodiment, showing the state in which the tip of a rotating agitator moves while being constrained by a rib it is in contact with. [Figure 5] This is a partially schematic cross-sectional view similar to Figure 4, showing the behavior of the tip when the rib separates from the tip of the agitator. [Modes for carrying out the invention]

[0017] The following describes embodiments of the present invention with reference to the drawings.

[0018] (Example) As shown in FIG. 1, the developing device 3 of the example is an example of a specific aspect of the developing device of the present invention. The developing device 3 is provided in the image forming apparatus 1. The image forming apparatus 1 is a monochrome laser printer that forms an image on a sheet SH by an electrophotographic method.

[0019] The image forming apparatus 1 includes an apparatus main body 9, a sheet feeding unit 20, a developing device 3, a photoreceptor 5, a scanner unit 8, a fixing unit 7, and a discharging unit 29.

[0020] The apparatus main body 9 is a substantially box-shaped body and has a plurality of frame members (not shown) inside. A sheet cassette 9C is detachably provided at the lower part inside the apparatus main body 9. Inside the sheet cassette 9C, sheets SH on which images are to be formed are stored in a stacked state. The sheet SH is paper, an OHP sheet, or the like.

[0021] A discharge tray 9D is provided on the upper surface of the apparatus main body 9. Sheets SH on which image formation has been completed are discharged onto the discharge tray 9D. A sheet feeding unit 20 is provided at the front part of the apparatus main body 9. The sheet feeding unit 20 conveys the sheet SH accommodated in the discharge tray 9D to the developing device 3. A fixing unit 7 is provided at the rear part of the apparatus main body 9. The fixing unit 7 heats and presses the sheet SH that has passed through the developing device 3. [[ID=??]]

[0022] [[ID=??]]<00→ A conveyance path P1 is provided inside the apparatus main body 9. The conveyance path P1 is a path that makes a U-turn upward from the front end part of the sheet cassette 9C, passes through the sheet feeding unit 20 while making a U-turn, then advances substantially horizontally backward, passes through the developing device 3 and the fixing unit 7, and further makes a U-turn upward, passes through the discharging unit 29, and reaches the discharge tray 9D.

[0023] It seems there are some incorrect or incomplete tags in the original text (the "??" marked lines), but I've translated it as accurately as possible based on the provided rules.The sheet supply unit 20 feeds the sheets SH contained in the sheet cassette 9C one by one to the transport path P1 using the feed roller 21, the separation roller 22, and the separation pad 22A. The sheet supply unit 20 then transports the sheets SH toward the developing device 3 using the transport roller 23A and pinch roller 23P, and the register roller 24A and pinch roller 24P, which are arranged along the transport path P1.

[0024] The photoreceptor 5 and the developing device 3 that supplies toner T1 to the photoreceptor 5 constitute a so-called developing cartridge, and are detachably mounted on the main body 9 of the device.

[0025] As shown in Figure 2, the developing apparatus 3 has a housing 40. The housing 40 is made up of multiple resin molded parts combined to partition the internal space.

[0026] The housing 40 has a toner storage chamber 41 and a developing chamber 43 inside. The toner storage chamber 41 and the developing chamber 43 are arranged in the front-to-back direction. In this embodiment, the toner storage chamber 41 is located in front of the developing chamber 43.

[0027] The photoreceptor 5 is supported in the housing 40 so as to be rotatable around the photoreceptor axis X5 at a position located rearward from the developing chamber 43 in the housing 40. The photoreceptor axis X5 extends parallel to the width direction, which is perpendicular to the front-to-back and up-and-down directions.

[0028] The photoreceptor 5 is a cylindrical rotating body centered on the photoreceptor axis X5. A positively charged photosensitive layer is formed on the surface of the photoreceptor 5, corresponding to the positively charged toner T1. In some cases, a negatively charged photosensitive layer may be formed on the surface of the photoreceptor 5; in this case, a negatively charged toner would be used. The photoreceptor 5 rotates in the clockwise direction of Figure 2 by a driving force transmitted from a drive source (not shown).

[0029] The lower part of the photoreceptor 5 protrudes below the housing 40 and can contact the sheet SH being transported towards the developing device 3 by the sheet supply unit 20 from above.

[0030] The inner wall surface 44 of the housing 40 has a curved inner wall surface 46 and a lower inner wall surface 45.

[0031] The curved inner wall surface 46 is located in the front part of the housing 40 and partitions the toner storage chamber 41 from below. The curved inner wall surface 46 is the same curved surface as a part of the cylindrical surface centered on the rotation axis X35 parallel to the width direction, or a curved surface that extends along a part of that cylindrical surface.

[0032] The rear end of the curved inner wall surface 46 is located behind and above the lowest part of the curved inner wall surface 46. The rotation axis X35 is located approximately in the center of the toner storage chamber 41 when viewed along the width direction.

[0033] The lower inner wall surface 45 is located in the middle of the housing 40 in the front-to-back direction and partitions the developing chamber 43 from below. The front end of the lower inner wall surface 45 is connected to the rear end of the curved inner wall surface 46. The lower inner wall surface 45 is an inclined surface that slopes downward toward the rear from its front end. The rear end of the lower inner wall surface 45 is located slightly forward from the lower part of the photoreceptor 5.

[0034] The toner storage chamber 41 and the developing chamber 43 are in communication above the ridge line 47 where the front end of the lower inner wall surface 45 and the rear end of the curved inner wall surface 46 connect.

[0035] As shown in Figure 1, the toner storage chamber 41 stores the toner T1. The toner T1 is transferred from the toner storage chamber 41 to the developing chamber 43. In Figures 2 and onward, the toner T1 is only shown in the areas necessary to explain the flow of toner T1 returning to the toner storage chamber 41.

[0036] As shown in Figure 2, the developing apparatus 3 includes a charger 37 and an agitator 35. The charger 37 is located at the rear end of the housing 40 and faces the photoreceptor 5 from the rear. The charger 37 is a well-known scorotron charger. The agitator 35 is located in the toner storage chamber 41 and has an agitator body 35B and a flexible plate 35F.

[0037] The agitator body 35B is supported by the housing 40 so as to be rotatable around the rotation axis X35. The agitator body 35B is a rigid body that extends in the width direction with a length close to the inner width of the toner storage chamber 41. In this embodiment, the agitator body 35B is made of a highly rigid resin material.

[0038] The agitator body 35B rotates in the clockwise direction of Figure 2 due to the transmission of driving force from a drive source (not shown).

[0039] The flexible plate 35F is made of a material with lower rigidity than the agitator body 35B, and is a flat plate member that easily flexes when subjected to force and easily returns to its initial shape when that force is removed.

[0040] In this embodiment, the flexible plate 35F is made of a flexible film material such as polyethylene terephthalate (PET). It is also possible to make the flexible plate 35F from rubber material, soft resin material, etc.

[0041] One end of the flexible plate 35F is attached to the agitator body 35B. The flexible plate 35F protrudes radially outward. Like the agitator body 35B, the flexible plate 35F also extends in the width direction with a length close to the inner width of the toner storage chamber 41. The flexible plate 35F rotates together with the agitator body 35B in the clockwise direction of Figure 2.

[0042] The agitator 35 shown by the solid line in Figure 2 represents a state in which the tip portion 35A of the flexible plate 35F, which rotates integrally with the agitator body 35B, is not constrained, and the flexible plate 35F is in its initial shape.

[0043] On the other hand, the agitator 35 shown by the dashed line in Figure 2 is in a state where the tip 35A of the flexible plate 35F, which rotates integrally with the agitator body 35B, is in contact with the curved inner wall surface 46 and moves while being constrained by the curved inner wall surface 46, and the flexible plate 35F is bent in the opposite direction to the rotation direction of the agitator body 35B.

[0044] The agitator 35 stirs the toner T1 contained in the toner storage chamber 41 by rotating the agitator body 35B and the flexible plate 35F together within the toner storage chamber 41. The flexible plate 35F then returns from a bent state, as shown by the dashed line in Figure 2, to its initial shape, as shown by the solid line in Figure 2, thereby transferring the toner T1 from the toner storage chamber 41 to the developing chamber 43.

[0045] The developing apparatus 3 includes a developing roller 31, a layer thickness regulating blade 38, a supply roller 32, and a toner scraping body 33, all located in the developing chamber 43.

[0046] The developing roller 31 is supported by the housing 40 so as to be rotatable around the rotation axis X31. The rotation axis X31 is located forward of the photoreceptor axis X5 and slightly above the photoreceptor axis X5, and extends parallel to the width direction.

[0047] The developing roller 31 has a smaller diameter than the photoreceptor 5 and contacts the photoreceptor 5 from the front. The developing roller 31 rotates in the counterclockwise direction shown in Figure 2 by a driving force transmitted from a drive source (not shown).

[0048] The layer thickness regulating blade 38 is cantilevered and supported on the upper wall of the housing 40 in a portion located above the developing roller 31. The layer thickness regulating blade 38 extends inclined downward and forward. The tip of the layer thickness regulating blade 38 contacts the portion of the developing roller 31 located above and in front of it.

[0049] The supply roller 32 is supported by the housing 40 so as to be rotatable around the rotation axis X32. The rotation axis X32 is located forward of the rotation axis X31 of the developing roller 31, and slightly below the rotation axis X31, and extends parallel to the width direction.

[0050] The supply roller 32 has a smaller diameter than the developing roller 31 and contacts the developing roller 31 from the front. The supply roller 32 is located above the midpoint in the front-rear direction of the lower inner wall surface 45.

[0051] The gap between the lower end of the supply roller 32 and the lower inner wall surface 45 is narrowed. The supply roller 32 rotates counterclockwise in the plane of Figure 2 due to a driving force transmitted from a drive source (not shown).

[0052] The toner scraping body 33 is a roller supported by the housing 40 so as to be rotatable around a rotation axis X33. The rotation axis X33 is located forward from the rotation axis X32 of the supply roller 32, and slightly above the rotation axis X32, and extends parallel to the width direction.

[0053] The toner scraping body 33 has a smaller diameter than the supply roller 32 and contacts the supply roller 32 from the front. In this embodiment, the diameter of the toner scraping body 33 is less than half the diameter of the supply roller 32.

[0054] The toner scraping body 33 is located above the lower inner wall surface 45. The gap between the lower end 33D of the toner scraping body 33 and the lower inner wall surface 45 is somewhat larger than the gap between the lower end of the supply roller 32 and the lower inner wall surface 45.

[0055] The upper end 33U of the toner scraping body 33 is located below the upper end 32U of the supply roller 32. The toner scraping body 33 rotates in the clockwise direction of Figure 2 by being driven by the supply roller 32.

[0056] As shown in Figures 2 and 3, the housing 40 has a plurality of ribs 50. As shown in Figure 3, each rib 50 is arranged so as to be spaced apart from each other in the width direction.

[0057] In Figure 3, CL1 is defined as the center line that passes through the center of the toner storage chamber 41 in the width direction and extends in the front-to-back direction. In Figure 3, to simplify the drawing, the inner width of the toner storage chamber 41 is shown as smaller than it actually is, and the number of ribs 50 is also shown as fewer than it actually is.

[0058] As shown in Figure 2, each rib 50 is positioned between the toner storage chamber 41 and the toner scraping body 33 in the front-rear direction. More specifically, the front end of each rib 50 is in contact with the ridge 47 where the front end of the lower inner wall surface 45 and the rear end of the curved inner wall surface 46 connect. The rear end of each rib 50 is located at a position forward of the toner scraping body 33.

[0059] Each rib 50 protrudes upward from the lower inner wall surface 45. Each rib 50 has a roughly triangular shape when viewed along the width direction, with its upper end 50U as the apex. Each rib 50 has a contact surface 50A. The contact surface 50A is an inclined surface that slopes upward from the front end of each rib 50 toward the toner scraping body 33 in the front-rear direction, reaching the upper end 50U.

[0060] In Figure 2, let K1 be a virtual line extending horizontally in the front-to-back direction, passing through the lower end 33D of the toner scraping body 33. Let K2 be a virtual line extending horizontally in the front-to-back direction, passing through the upper end 32U of the toner scraping body 33.

[0061] Let K3 be a virtual line extending horizontally in the front-rear direction, passing through the rotation axis X35 of the agitator 35. Let K4 be a virtual line extending horizontally in the front-rear direction, passing through the upper end 32U of the supply roller 32.

[0062] As is clear from comparing the vertical relationship with the virtual line K1, the upper end 50U of each rib 50 is located above the lower end 33D of the toner scraping body 33. More specifically, as is clear from comparing the vertical relationship with the virtual line K2, the upper end 50U of each rib 50 is located above the upper end 33U of the toner scraping body 33.

[0063] As is evident from the comparison of the vertical relationship with the virtual line K3, the upper end 50U of each rib 50 is located below the rotational axis X35 of the agitator 35. As is evident from the comparison of the vertical relationship with the virtual line K4, the upper end 50U of each rib 50 is located below the upper end 32U of the supply roller 32.

[0064] As shown in Figure 3, each rib 50 extends along the front-rear direction. More specifically, each rib 50 extends backward from its front end, which is in contact with the ridge line 47, toward the toner scraping body 33.

[0065] Each rib 50 includes multiple inclined ribs 52A-52F, 53A-53F and one central rib 51.

[0066] Each inclined rib 52A to 52F located on one side in the width direction relative to the center line CL1, and each inclined rib 53A to 53F located on the other side in the width direction relative to the center line CL1, are symmetrical with respect to the center line CL1 as the axis of symmetry. For this reason, the specific configuration of each inclined rib 52A to 52F will be described, while the specific configuration of each inclined rib 53A to 53F will be omitted as appropriate.

[0067] Each inclined rib 52A-52F, 53A-53F is inclined to approach the center in the width direction (center line CL1) as it moves from the developing chamber 43 towards the toner storage chamber 41 in the front-rear direction, that is, as it moves forward from the toner scraping body 33 towards the toner storage chamber 41.

[0068] One central rib 51 is located more centrally in the width direction than each of the inclined ribs 52A-52F and 53A-53F, and extends parallel to the longitudinal direction so as to coincide with the center line CL1.

[0069] The spacing W6 between two adjacent first ribs (inclined ribs 52F, 52E) located on the outer side in the width direction is greater than the spacing W5 between two adjacent second ribs (inclined ribs 52E, 52D) located in the center of the width direction.

[0070] The spacing W5 between two adjacent first ribs (inclined ribs 52E, 52D) located on the outer side in the width direction is greater than the spacing W4 between two adjacent second ribs (inclined ribs 52D, 52C) located in the center of the width direction.

[0071] The spacing W4 between two adjacent first ribs (inclined ribs 52D, 52C) located on the outer side in the width direction is greater than the spacing W3 between two adjacent second ribs (inclined ribs 52C, 52B) located in the center of the width direction.

[0072] The distance W3 between two adjacent first ribs (inclined ribs 52C, 52B) located on the outer side in the width direction is greater than the distance W2 between two adjacent second ribs (inclined ribs 52B, 52A) located in the center of the width direction.

[0073] The distance W2 between two adjacent first ribs (inclined ribs 52B, 52A) located on the outer side in the width direction is greater than the distance W1 between two adjacent second ribs (inclined rib 52A, central rib 51) located in the center of the width direction.

[0074] The same relative sizes apply to each of the inclined ribs 53A to 53F and the central rib 51.

[0075] As shown in Figures 4 and 5, the contact surface 50A and upper end 50U of each rib 50 can come into contact with the tip portion 35A of the flexible plate 35F of the agitator 35.

[0076] The flexible plate 35F shown by the solid line in Figure 5 represents the state just before the tip portion 35A separates from the contact surface 50A and upper end 50U of each rib 50.

[0077] On the other hand, the flexible plate 35F shown by the dashed line in Figure 5 shows the state in which the tip portion 35A immediately returns to its initial shape after separating from the upper end 50U of each rib 50.

[0078] Each rib 50 is positioned so as to be separated from the tip 35A of the flexible plate 35F of the rotating agitator 35 above the lower end 33D of the toner scraping body 33. More specifically, each rib 50 is positioned so as to be separated from the tip 35A of the flexible plate 35F of the rotating agitator 35 above the upper end 33U of the toner scraping body 33 and below the upper end 32U of the supply roller 32.

[0079] The scanner unit 8 is located above the developing device 3. The scanner unit 8 has a well-known configuration including a laser light source, a polygon mirror, an fθ lens, and a reflector. The scanner unit 8 irradiates the surface of the photoreceptor 5 with a laser beam from above.

[0080] The surface of the photoreceptor 5 is uniformly positively charged by the charger 37 as it rotates, and then exposed by high-speed scanning of a laser beam irradiated from the scanner unit 8. As a result, an electrostatic latent image corresponding to the image to be formed on the sheet SH is formed on the surface of the photoreceptor 5.

[0081] The supply roller 32 supplies the toner T1, which has been transferred from the toner storage chamber 41 to the developing chamber 43 by the agitator 35, to the developing roller 31.

[0082] In this process, the toner scraping body 33 scrapes off the toner T1 adhering to the surface of the supply roller 32, thereby reliably stabilizing the amount of toner T1 supplied by the supply roller 32 to the developing roller 31.

[0083] The layer thickness regulating blade 38 scrapes off excess toner T1 so that the toner T1 adhering to the surface of the developing roller 31 has a predetermined layer thickness.

[0084] The developing roller 31 then supplies toner T1 to the photoreceptor 5 in response to the electrostatic latent image formed on the surface of the photoreceptor 5. As a result, a toner image is placed on the surface of the photoreceptor 5. This toner image is then transferred to a sheet SH that passes below the developing device 3.

[0085] The fixing unit 7 is located behind the developing device 3. The fixing unit 7 includes a heating roller 7A located above the transport path P1, and a pressure roller 7B facing the heating roller 7A from below, with the transport path P1 in between.

[0086] The fixing unit 7 heats and pressurizes the sheet SH with the heating roller 7A and the pressure roller 7B while transporting it toward the discharge unit 29, thereby heat-fixing the toner image onto the sheet SH.

[0087] The discharge unit 29 uses the discharge roller 29A and the discharge pinch roller 29P to discharge the sheet SH on which the toner image has been fixed into the discharge tray 9D.

[0088] <Effects and Effects> In the developing apparatus 3 of the embodiment, as shown in Figure 4, the toner T1 scraped off by the toner scraping body 33 from the supply roller 32 falls toward the lower inner wall surface 45, and further flows forward toward the toner storage chamber 41 due to the inertial force of the rotation of the supply roller 32, attempting to return to the toner storage chamber 41.

[0089] In this process, the tip 35A of the flexible plate 35F of the rotating agitator 35 moves while being constrained by the contact surfaces 50A of the ribs 50 that it comes into contact with.

[0090] Then, as shown in Figure 5, when the upper end 50U of each rib 50 is relatively separated from the tip 35A of the flexible plate 35F above the lower end 33D of the toner scraping body 33, the tip 35A of the flexible plate 35F is no longer constrained by each rib 50 and immediately returns to the initial shape shown by the dashed line in Figure 5.

[0091] As a result, the flow of toner T1, which is agitated by the agitator 35 and moves from the toner storage chamber 41 towards the developing chamber 43, is more likely to occur above the upper end 50U of each rib 50. In other words, the tip 35A of the flexible plate 35F of the agitator 35 is less likely to obstruct the flow of toner T1 returning to the toner storage chamber 41, at least below the lower end 33D of the toner scraping body 33, and more specifically, at least below the upper end 33U of the toner scraping body 33.

[0092] Therefore, the developing apparatus 3 of the embodiment can suppress the accumulation of toner T1 below the supply roller 32 and toner scraping body 33 within the housing 40. The same applies to the image forming apparatus 1 of the embodiment that includes the developing apparatus 3.

[0093] Furthermore, in this developing apparatus 3, each rib 50 protrudes upward from the lower inner wall surface 45 of the housing 40 and extends along the front-rear direction toward the toner scraping body 33, making it difficult to obstruct the flow of toner T1 that is trying to return to the toner storage chamber 41 on the lower inner wall surface 45.

[0094] Furthermore, in this developing apparatus 3, the upper end 50U of each rib 50 is located above the lower end 33D of the toner scraping body 33. This configuration allows each rib 50 to reliably separate from the tip 35A of the flexible plate 35F of the rotating agitator 35 above the lower end 33D of the toner scraping body 33.

[0095] Furthermore, in this developing device 3, the upper end 50U of each rib 50 is located above the upper end 33U of the toner scraping body 33. With this configuration, the tip 35A of the flexible plate 35F of the agitator 35 is less likely to obstruct the flow of toner T1 returning to the toner storage chamber 41, at least below the upper end 33U of the toner scraping body 33. As a result, this developing device 3 can further suppress the accumulation of toner T1 below the supply roller 32 and the toner scraping body 33 within the housing 40.

[0096] Furthermore, in this developing apparatus 3, the upper end 50U of each rib 50 is located below the rotation axis X35 of the agitator 35. This configuration ensures that the flexible plate 35F of the agitator 35 has the ability to transfer toner T1 from the toner storage chamber 41 to the developing chamber 43, while also making it less likely for the tip 35A of the flexible plate 35F of the agitator 35 to obstruct the flow of toner T1 returning to the toner storage chamber 41.

[0097] Furthermore, in this developing apparatus 3, the upper end 50U of each rib 50 is located below the upper end 32U of the supply roller 32. This configuration ensures that the flexible plate 35F of the agitator 35 has sufficient capacity to transfer toner T1 from the toner storage chamber 41 to the developing chamber 43, while also making it less likely for the tip 35A of the flexible plate 35F of the agitator 35 to obstruct the flow of toner T1 returning to the toner storage chamber 41.

[0098] Furthermore, in this developing apparatus 3, as shown in Figure 3, each rib 50 is arranged so as to be spaced apart from each other in the width direction. This configuration makes it possible to suppress width-direction variations in the behavior of the tip 35A of the flexible plate 35F of the agitator 35 when it moves while being constrained by the contact surfaces 50A of each rib 50, as shown in Figure 4, and in the behavior of the tip 35A of the flexible plate 35F when the upper end 50U of each rib 50 is relatively far away from the tip 35A of the flexible plate 35F of the agitator 35, as shown in Figure 5.

[0099] Furthermore, in this developing apparatus 3, as shown in Figure 3, each rib 50 includes a plurality of inclined ribs 52A-52F, 53A-53F that incline towards the center in the width direction (center line CL1) as it moves from the developing chamber 43 towards the toner storage chamber 41 in the front-rear direction, that is, as it moves forward from the toner scraping body 33 towards the toner storage chamber 41. With this configuration, each inclined rib 52A-52F, 53A-53F can direct the flow of toner T1 that is trying to return to the toner storage chamber 41 towards the center in the width direction.

[0100] Furthermore, in this developing apparatus 3, each rib 50 is located more centrally in the width direction than each inclined rib 52A-52F, 53A-53F and includes a central rib 51 that extends parallel to the front-to-back direction. With this configuration, the central rib 51 does not obstruct the flow of toner T1 returning to the toner storage chamber 41 from being directed towards the center in the width direction, and the effects of each rib 50 described above can be exerted.

[0101] Furthermore, in this developing apparatus 3, as shown in Figure 3 with intervals W1 to W6, the spacing between two adjacent first ribs located on the outer side in the width direction is greater than the spacing between two adjacent second ribs located in the center in the width direction. With this configuration, the closer each rib 50 is to the center in the width direction, the more reliably it can exert the effects described above.

[0102] Furthermore, in this developing apparatus 3, as shown in Figure 4, the toner scraping body 33 is a roller rotatably supported by the housing 40. With this configuration, the rotating toner scraping body 33 effectively scrapes off excess toner T1 from the supply roller 32, thereby ensuring a stable and reliable amount of toner T1 supplied by the supply roller 32 to the developing roller 31.

[0103] Furthermore, in this developing apparatus 3, the contact surface 50A that abuts the tip 35A of the flexible plate 35F of the agitator 35 on each rib 50 inclins upward toward the toner scraping body 33 in the front-rear direction and reaches the upper end 50U of each rib 50. With this configuration, the tip 35A of the flexible plate 35F of the agitator 35 can move smoothly toward the upper end 50U of each rib 50 while abutting the contact surface 50A of each rib 50.

[0104] Although the present invention has been described above with reference to examples, it goes without saying that the present invention is not limited to the above examples and can be applied with appropriate modifications without departing from its spirit.

[0105] In the embodiment, the toner scraping body 33 is a roller that rotates in accordance with the supply roller 32, but the present invention is not limited to this configuration. For example, the toner scraping body may be a drive roller that rotates in the same direction as or opposite to the supply roller by a driving force transmitted from a drive source (not shown). Alternatively, the toner scraping body may be a non-rotatable scraping blade or shaft, etc.

[0106] In the embodiment, the agitator 35 has a flexible plate 35F, but the present invention is not limited to this configuration. For example, the present invention also includes a configuration in which the agitator does not have a flexible plate, and the ribs are capable of contacting the tip of the agitator, and are positioned above the lower end of the toner scraping body from the tip of the rotating agitator.

[0107] The developing apparatus 3 of the embodiment is a so-called horizontal developing apparatus, in which the toner storage chamber 41 and the developing chamber 43 are arranged in the front-to-back direction, and the toner stored in the toner storage chamber 41 is supplied to the developing chamber 43 along the front-to-back direction. However, the present invention is not limited to this configuration. For example, the developing apparatus of the present invention may be a so-called vertical developing apparatus, in which the toner storage chamber 41 is located above the developing chamber 43 and toner is supplied downward from the toner storage chamber 41 to the developing chamber 43, or in which the toner storage chamber 41 is located below the developing chamber 43 and toner is supplied upward from the toner storage chamber 41 to the developing chamber 43.

[0108] The image forming apparatus 1 in the embodiment is a monochrome laser printer equipped with one developing apparatus 3, but the present invention is not limited to this configuration. For example, the image forming apparatus of the present invention may be a color printer equipped with multiple developing apparatuses that support multiple colors. [Industrial applicability]

[0109] The present invention can be used, for example, in an image forming apparatus, or a multifunction device equipped with both an image forming function and an image reading function. [Explanation of Symbols]

[0110] 1…Image forming apparatus, 3…Developing apparatus, 31…Developing roller, T1…Toner 32... Supply roller, 41... Toner storage room, 43... Developing room 40...Housing, 33...Toner scraping unit, 35...Agitator 35A...Agitator tip, 50...Rib 33D...Lower end of toner scraping body, 44...Inner wall surface of the housing 45...Lower inner wall surface, 50U...Upper end of rib, 33U...Upper end of toner scraping body X35...Axis of rotation of the agitator, 32U...Upper end of the supply roller 52A-52F, 53A-53F...inclined ribs, 51...central rib 50A... Contact surface of the rib, 5... Photoreceptor

Claims

1. Developing roller and A supply roller that supplies toner to the developing roller, A housing having a toner storage chamber for storing toner, and a developing chamber in which the developing roller and the supply roller are arranged, A toner scraping body is placed in the developing chamber and contacts the supply roller to scrape off toner adhering to the surface of the supply roller, The toner storage chamber includes an agitator that rotates within the toner storage chamber to agitate the toner, The toner storage chamber and the developing chamber are arranged in the front-to-back direction. The housing is positioned between the toner storage chamber and the toner scraping body in the front-rear direction and has a rib that can contact the tip of the agitator, and the rib is provided so as to be separated from the tip of the rotating agitator at a point above the lower end of the toner scraping body. The inner wall surface of the housing has a lower inner wall surface located below the supply roller and the toner scraping body. The ribs protrude upward from the lower inner wall surface and extend along the front-rear direction toward the toner scraping body. A developing apparatus characterized in that a plurality of the ribs are arranged at intervals from one another in the width direction parallel to the rotation axis of the agitator.

2. The developing apparatus according to claim 1, wherein the upper end of each rib is located above the lower end of the toner scraping body.

3. The developing apparatus according to claim 2, wherein the upper end of each rib is located above the upper end of the toner scraping body.

4. The developing apparatus according to claim 2 or 3, wherein the upper end of each rib is located below the rotation axis of the agitator.

5. The developing apparatus according to claim 4, wherein the upper end of each rib is located below the upper end of the supply roller.

6. The developing apparatus according to any one of claims 1 to 5, wherein each of the ribs includes a plurality of inclined ribs that are inclined to approach the center in the width direction as they move from the developing chamber toward the toner storage chamber in the front-rear direction.

7. The developing apparatus according to claim 6, wherein each of the ribs is located more centrally in the width direction than each of the inclined ribs and includes a central rib that extends parallel to the front-rear direction.

8. The developing apparatus according to any one of claims 1 to 7, wherein the distance between two adjacent first ribs located on the outer side in the width direction is greater than the distance between two adjacent second ribs located in the center in the width direction than the distance between the first ribs.

9. The developing apparatus according to any one of claims 1 to 8, wherein the toner scraping body is a roller rotatably supported in the housing.

10. The developing apparatus according to any one of claims 1 to 9, wherein the contact surface of each rib that contacts the tip of the agitator in the front-rear direction slopes upward toward the toner scraping body in the front-rear direction and reaches the upper end of each rib.

11. Photoreceptor and A developing apparatus according to any one of claims 1 to 10, which supplies toner to the photoreceptor, An image forming apparatus characterized by comprising:

Images