Developing device and image forming apparatus

Abstract

Provided are a developing device and an image forming apparatus. The developing device has a first conveying member and a second conveying member configured in a first conveying path and a second conveying path formed one above the other in a gravitational direction to convey developer in a manner that the developer circulates between the first conveying path and the second conveying path, a developing member configured opposite the first conveying path to be supplied with the developer from the first conveying path, and a third conveying member provided in a third conveying path that conveys developer that is not used in the developing member back to the second conveying path, an axis of the second conveying member being configured at a position higher than an axis of the third conveying member in the gravitational direction.

Description

Technical Field

[0001] This invention relates to developing apparatus and image forming apparatus. Background Technology

[0002] Japanese Patent Application Publication No. 2009-175768 discloses a developing apparatus comprising a developing container, a first stirring member, a second stirring member, and a connecting passage. The developing container includes: a developing roller that delivers toner to a developing area where an electrostatic latent image is developed into a toner image; a developing roller housing that houses the developing roller; a first stirring chamber disposed obliquely below the developing roller housing; and a second stirring chamber adjacent to the developing roller housing and disposed above the first stirring chamber. The first stirring member is housed in the first stirring chamber and stirs the toner within the first stirring chamber while conveying it in a predetermined first conveying direction. The second stirring member... The toner, housed in the second stirring chamber, is stirred while being conveyed in a second conveying direction opposite to the first conveying direction. A connecting path is provided to convey the toner from the downstream end of the first stirring chamber in the first conveying direction to the upstream end of the second stirring chamber in the second conveying direction, connecting the downstream end of the first stirring chamber in the first conveying direction to the upstream end of the second stirring chamber in the second conveying direction. The portion of the connecting path closest to the developing roller on the side of the connecting path relative to the rotation axis of the first stirring member away from the developing roller, and on the surface of the connecting path facing the second stirring chamber, is formed vertically below the axis of the developing roller. The developing apparatus also includes a residual developer conveying component for stirring and conveying the developer retained between the developing roller and the first stirring member. Summary of the Invention

[0003] The object of the present invention is to provide a developing apparatus and an image forming apparatus, wherein, in a developing apparatus having a first transport path and a second transport path arranged vertically adjacent to each other in the gravity direction, and a third transport path for recycling developer not used in the developing unit to the second transport path, the size in the gravity direction can be reduced compared to a structure in which the third transport path is arranged above the second transport path in the gravity direction.

[0004] According to a first aspect of the present invention, a developing apparatus is provided, comprising: a first conveying member and a second conveying member disposed on a first conveying path and a second conveying path formed vertically along the direction of gravity, wherein developer is conveyed in such a manner that developer circulates between the first conveying path and the second conveying path; a developing member disposed opposite to the first conveying path, wherein developer is supplied from the first conveying path; and a third conveying member disposed on a third conveying path, the third conveying path being used to recover and convey developer not used in the developing member to the second conveying path, wherein the axis of the second conveying member is disposed above the axis of the third conveying member in the direction of gravity.

[0005] According to a second aspect of the invention, a separator of a predetermined height is formed between the second conveying path and the third conveying path.

[0006] According to a third aspect of the invention, the upper end of the separating member is located above the direction of gravity of an imaginary straight line connecting the axis of the second conveying member and the axis of the third conveying member.

[0007] According to a fourth aspect of the invention, a return prevention component is formed between the second transport path and the third transport path, which prevents developer transported from the third transport path to the second transport path from returning to the third transport path.

[0008] According to a fifth aspect of the present invention, the return prevention component is configured to allow developer to move from the third transport path to the second transport path, while preventing developer from moving from the second transport path to the third transport path.

[0009] According to a sixth aspect of the present invention, an image forming apparatus is provided, which has the developing apparatus and a latent image holder disposed opposite to the developing apparatus.

[0010] (Effect)

[0011] According to the first scheme, in a developing apparatus having a first conveying path and a second conveying path arranged vertically adjacent to each other in the gravity direction, and a third conveying path for recycling developer that is not used in the developing unit to the second conveying path, the size in the gravity direction can be reduced compared to a structure in which the third conveying path is arranged above the second conveying path in the gravity direction.

[0012] According to the second scheme, it is possible to prevent the developer recovered to the second transport path from returning to the third transport path.

[0013] According to the third scheme, it is possible to allow the developer to be recovered from the third transport path to the second transport path, and it is possible to prevent the developer from returning from the third transport path to the second transport path.

[0014] According to the fourth scheme, the developer can always be transported unidirectionally from the third transport path to the second transport path.

[0015] According to the fifth scheme, it is possible to prevent developer from remaining between the third transport path and the second transport path.

[0016] According to the sixth embodiment, an image forming apparatus can be provided that, in a developing apparatus having a first transport path and a second transport path arranged vertically adjacent to each other in the gravity direction, and a third transport path for recycling developer not used in the developing unit to the second transport path, can reduce the size in the gravity direction compared to a structure in which the third transport path is arranged at a position above the second transport path in the gravity direction. Attached Figure Description

[0017] Figure 1 This is a side view showing the structure of the image forming apparatus according to an embodiment of the present invention.

[0018] Figure 2 This is a cross-sectional view of the developing apparatus according to an embodiment of the present invention, viewed from the direction extending from the developing apparatus.

[0019] Figure 3 This is a cross-sectional view of the developing apparatus according to an embodiment of the present invention, viewed from the front side. Detailed Implementation

[0020] Next, embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 An image forming apparatus 10 according to an embodiment of the present invention is shown. The image forming apparatus 10 has an image forming apparatus body 12, and an image forming unit 14, a transfer device 16, a fixing device 18, and a paper feeding device 20 are disposed within the image forming apparatus body 12. In addition, a recording medium transport path 22 for transporting a recording medium such as paper is formed within the image forming apparatus body 12.

[0021] The image forming unit 14 forms an image on a recording medium using an electrophotographic method. The image forming unit 14 has multiple (e.g., four) image forming units 24. The four image forming units 24 form toner images of different colors, such as yellow, magenta, cyan, and black.

[0022] Each image forming unit 24 has a photosensitive drum 26. The photosensitive drum 26 is an example of an image holder, in which a toner image to be transferred to a recording medium is held on its outer peripheral surface and rotated. In addition, the image forming unit 24 is provided with a charging device 28 for charging the photosensitive drum 26, a developing device 30 for developing the latent image obtained by charging with a developing agent, and a cleaning device 32 for cleaning the transferred photosensitive drum 26. A light writing device 48 for forming a latent image on the charged photosensitive drum 26 is also provided.

[0023] The transfer apparatus 16 has an intermediate transfer belt 34. The toner image is transferred from the photosensitive drum 26 to the intermediate transfer belt 34 in one step by the primary transfer unit 36, and the primary transfer unit 38 transfers the toner image to the recording medium in a second step.

[0024] The intermediate transfer belt 34 is supported by multiple support members 40 so that it can rotate. In addition, a support member 42 is provided opposite to the secondary transfer member 38.

[0025] The fixing device 18 uses, for example, heat and pressure to fix the toner image transferred onto the recording medium onto the recording medium.

[0026] The paper feeding device 20 includes: a storage section 44 for storing recording media in a stacked state; and a delivery member 46 for delivering the recording media stored in the storage section 44 toward the recording media transport path 22.

[0027] The recording medium transport path 22 transports the recording medium from the paper feeding device 20 to the secondary transfer unit 38 and the support unit 42, then to the fixing unit 18, and then to the image forming device body 12.

[0028] In the image forming apparatus 10 configured as described above, toner images formed on the outer peripheral surface of the photosensitive drum 26 are transferred once to the intermediate transfer belt 34, the toner images transferred once to the intermediate transfer belt 34 are transferred a second time to the recording medium, and the toner images transferred a second time to the recording medium are fixed to the recording medium by the fixing device 18.

[0029] Next, refer to Figure 2The developing apparatus 30 of this embodiment will be described. This developing apparatus 30 is a two-component developing apparatus in which a developer composed of a carrier and a toner is stirred, causing the toner to become charged, and thus developing the product. In the following description, "upward" in the direction of gravity is referred to as "up," and "downward" in the direction of gravity is referred to as "down." When no distinction is made between up and down, it is referred to as "upward and downward" in the direction of gravity, or simply "upward and downward direction." Furthermore, the direction in which the developing roller 52, the first conveying member 82, the second conveying member 84, etc., which are perpendicular to the direction of gravity, extend, as described later, is referred to as the axial direction. And, for convenience, the side of the first conveying path 62 where the developer supply port 70 is formed, i.e., [the side described later], is referred to as [the side where the first conveying path 62 is formed]. Figure 3 The left side of the paper in the diagram is called the supply end side, and the side of the second conveying path 64 described later, where the lower discharge outlet 80 is formed, i.e., the right side of the paper, is called the discharge end side.

[0030] The developing apparatus 30 is disposed opposite to the photosensitive drum 26, which serves as an image holder. The developing apparatus 30 has a developing apparatus body 50 in the shape of a developing apparatus housing. In the developing apparatus body 50, a developing roller 52, which serves as a developing component, is disposed opposite to the photosensitive drum 26. The developing roller 52 includes a magnetic roller 54 for forming a uniform magnetic field in the axial direction and a developing sleeve 56 rotatably mounted on the outer periphery of the magnetic roller 54. The magnetic roller 54 is fixed to the developing apparatus body 50 within the developing sleeve 56. The developing sleeve 56 is a cylindrical component made of a non-magnetic material and is supported to be rotatable relative to the developing apparatus body 50. In the developing apparatus body 50, a layer thickness limiting member 58 is fixed above the developing roller 52, opposite to the developing sleeve 56, and limits the layer thickness of the developer. The layer thickness limiting member 58 is formed of a metal plate. The toner adhering to the periphery of the developing sleeve 56 moves toward the latent image formed on the photosensitive drum 26 after its layer thickness is limited by the layer thickness limiting member 58.

[0031] The interior of the developing apparatus body 50 is separated by a partition wall 60 that divides the space vertically in the direction of gravity. The developing apparatus body 50 is provided with a first transport path 62 and a second transport path 64 formed vertically in the direction of gravity, respectively. The upper surface of the partition wall 60, which has an arc-shaped cross-section, constitutes the lower surface of the first transport path 62. Furthermore, the lower surface of the partition wall 60, which has an arc-shaped cross-section, constitutes the upper surface of the second transport path 64. The first transport path 62 and the second transport path 64 have the same axial length and extend axially. The developing roller 52 is configured to face the developer supply port 66 formed axially in the first transport path 62, and is supplied with developer from the first transport path 62.

[0032] like Figure 3As shown, the upper surface 68 of the developing apparatus body 50 is also the upper surface of the first transport path 62, but a developer supply port 70 is provided on the supply end side at a location corresponding to the upper part of the first transport path 62. A first connecting port 72 is formed on the partition wall 60 at a position below the developer supply port 70 in the direction of gravity. A second connecting port 74 is also provided on the partition wall 60 at a position closer to the discharge end than the first connecting port 72. In addition, an upper discharge port 76 is provided on the partition wall 60 near the discharge end side. The bottom surface 78 of the developing apparatus body 50 is also the bottom surface of the second transport path 64, and a lower discharge port 80 is formed on the bottom surface 78 at a position closest to the discharge end side.

[0033] A first conveying component 82 and a second conveying component 84 are respectively disposed in the first conveying path 62 and the second conveying path 64. The first conveying component 82 and the second conveying component 84 are rotatably arranged for stirring the developer between the first conveying path 62 and the second conveying path 64 and circulating the developer.

[0034] like Figure 2 As shown, a third transport path 86 is provided obliquely below the direction of gravity of the developing roller 52. This third transport path 86 is used to recover and transport unused developer in the developing roller 52 back to the second transport path 64. A third transport member 88 is rotatably arranged on this third transport path 86.

[0035] like Figure 3 As shown, the first conveying component 82, the second conveying component 84, and the third conveying component 88 each have shafts 90, 92, and 94, respectively. The feed end of the shaft 90 of the first conveying component 82 is supported on the upper part of the feed end of the developing apparatus body 50 by a first upper bearing B1, and the discharge end is supported on the upper part of the discharge end of the developing apparatus body 50 by a second upper bearing B2. Similarly, the feed end of the shaft 92 of the second conveying component 84 is supported on the lower part of the feed end of the developing apparatus body 50 by a first lower bearing B3, and the discharge end is supported on the lower part of the discharge end of the developing apparatus body 50 by a second lower bearing B4. Here, the second upper bearing B2 supporting the discharge end of the shaft 90 of the first conveying component 82 and the second lower bearing B4 supporting the discharge end of the shaft 92 of the second conveying component 84 are axially aligned.

[0036] In addition, the first conveying member 82, the second conveying member 84, and the third conveying member 88 are respectively provided with conveying blades 96, 98, and 100 that are spirally arranged around the shafts 90, 92, and 94 and inclined in the same direction.

[0037] The conveying blades 96 of the first conveying component 82 are formed around the axis 90 between the first connecting port 72 and the second connecting port 74. The conveying blades 98 of the second conveying component 84 are formed around the axis 92 between the first connecting port 72 and the second connecting port 74.

[0038] Furthermore, on the first conveying member 82, in the portion located between the second connecting port 74 and the upper discharge port 76, there are discharge conveying blades 102 whose blade inclination direction is opposite to that of the conveying blades 96, adjusting blades 104 whose inclination direction is the same as that of the conveying blades 96, and upper discharge blades 106 whose blade inclination direction is the same as that of the discharge conveying blades 102 and whose radial length is shorter. The discharge conveying blades 102 are formed as a part of the blades reaching the second connecting port 74. The upper discharge blades 106 are disposed in an upper discharge space 108 whose dimensions in the vertical and width directions are smaller than those of the first conveying path 62. The upper discharge space 108 is formed between the upwardly protruding portion of the partition wall 60 and the downwardly protruding portion formed by the upper surface of the first conveying path 62.

[0039] Additionally, on the second transport member 84, in the portion between the second communication port 74 and the lower discharge port 80, there is a developer return blade 110 with a blade incline opposite to that of the transport blade 98, and a lower discharge blade 112 with a blade incline in the same direction as the transport blade 98. The lower discharge blade 112 is disposed within a lower discharge space 114, which is smaller than the second transport path 64 in both the vertical and width directions. This lower discharge space 114 is formed between a downwardly protruding portion of the partition wall 60 and a protruding portion formed by the bottom surface of the second transport path 64 protruding upwards.

[0040] According to the above structure, the developer supplied from the developer supply port 70 falls downward in the direction of gravity in the first transport path 62 and is supplied to the second transport path 64 through the first connecting port 72. It is then transported in the second transport path 64 towards the discharge end via the second transport member 84 to a point near the area below the second connecting port 74. The transport of the developer near the area below the second connecting port 74 towards the discharge end is blocked by the developer return blade 110, causing it to collide with the developer further transported from the supply end side within the second transport path 64. As a result, the developer near the area below the second connecting port 74 is pushed upward in the direction of gravity and fed into the first transport path 62 through the second connecting port 74.

[0041] The developer supplied to the first transport path 62 is simultaneously transported by the transport blades 96 of the first transport member 82 toward the first connecting port 72 (i.e., the supply end direction) and supplied from the developer supply port 66 to the developing roller 52. The developer that is not supplied to the developing roller 52 and remains in the first transport path 62 is transported by the first transport member 82 in the replenishment end direction to the first connecting port 72, and then falls downward in the first connecting port 72 in the direction of gravity, and is supplied again to the second transport path 64, and the above cycle is repeated.

[0042] Additionally, a portion of the developer fed into the first transport path 62 from the second transport path 64 through the second connecting port 74 is conveyed towards the discharge end by the discharge transport blade 102, and then pushed back towards the replenishment end by the adjusting blade 104 to prevent the discharge of more than a predetermined amount of developer. Excess developer that does not return towards the replenishment end by the adjusting blade 104 is conveyed towards the discharge end in the upper discharge space 108 by the upper discharge blade 106, falls downwards in the direction of gravity at the upper discharge port 76, and is discharged into the lower discharge space 114 of the second transport path 64. Excess developer discharged into the lower discharge space 114 is further conveyed towards the discharge end by the lower discharge blade 112, and finally discharged from the lower discharge port 80 to the outside of the developing apparatus body 50.

[0043] Thus, the upper discharge port 76, the lower discharge port 80, the discharge conveying blade 102, the adjusting blade 104, the upper discharge blade 106, the upper discharge space 108, and the lower discharge blade 112 constitute a developer discharge structure that discharges excess developer discharged from the first conveying path 62 to the outside through the second conveying path 64.

[0044] On the other hand, the unused developer supplied from the first transport path 62 to the developing roller 52 after development is completed is stripped from the developing roller 52 to the third transport path 86, and further recovered from the third transport path 86 and transported to the second transport path 64, where it is mixed and stirred together with new developer supplied by a developer replenishment device (not shown) through the second transport member 84. Figure 3 As indicated by the arrow, the developing device body 50 is pushed up from the second connection port 74 to the first transport path 62 at the discharge end, and then supplied to the developing roller 52 again through the first transport component 82.

[0045] Here, the positional relationship between the developing roller 52, the second conveying member 84, and the third conveying member 88 is explained. For example... Figure 2As shown, the axis 92 of the second conveying member 84 is positioned above the axis 94 of the third conveying member 88 in the direction of gravity. Both the axis 92 of the second conveying member 84 and the axis 94 of the third conveying member 88 are positioned below the axis of the developing roller 52 in the direction of gravity. The axis 90 of the first conveying member 82 is positioned above the axis of the developing roller 52 in the direction of gravity.

[0046] Therefore, since the diameter of the third conveying member 88 is smaller than the diameter of the second conveying member 84, the positional relationship between the bottom surface 78 of the second conveying path 64 and the bottom surface of the third conveying path 86 can be either the same height in the direction of gravity, or the bottom surface of the second conveying path 64 is slightly higher or slightly lower than the bottom surface of the third conveying path 86. Furthermore, in this embodiment, an example has been described where the axis 92 of the second conveying member 84 is positioned above the axis 94 of the third conveying member 88 in the direction of gravity. However, as long as the diameters of the second and third conveying members 84 are appropriately selected to make the bottom surfaces of the second and third conveying paths 64 and 86 have the same vertical relationship, the axis 92 of the second conveying member 84 can also be at the same height as the axis 94 of the third conveying member 88, or slightly lower in the direction of gravity.

[0047] Furthermore, a partition member 116 of a predetermined height is formed between the second transport path 64 and the third transport path 86. This partition member 116 is a plate-like wall protruding axially from near the bottom surface of the second transport path 64 and the bottom surface of the third transport path 86 in the direction of gravity. The upper end 118 of the partition member 116 is located above, in the direction of gravity, an imaginary straight line connecting the axis 92 of the second transport path 84 and the axis 94 of the third transport path 88. The height of the partition member 116 in the direction of gravity can be any height, as long as the developer can be transported from the third transport path 86 to the second transport path 64 by the third transport path 88 and the developer transported from the third transport path 86 to the second transport path 64 can be prevented from returning to the third transport path 86.

[0048] Furthermore, the partition 116 between the second transport path 64 and the third transport path 86 can be any component that has the function of preventing the developer transported from the third transport path 86 to the second transport path 64 from returning to the third transport path, while allowing the developer to be transported from the third transport path 86 to the second transport path 64 through the third transport component 88. It can be any component that allows the developer to flow in one direction, such as a plate with a free end in the direction of gravity or an opening formed in the partition 116.

Claims

1. A developing apparatus comprising: A first conveying member and a second conveying member are configured in a first conveying path and a second conveying path that are partially overlapped vertically along the direction of gravity, so that the developer is conveyed in a manner that the developer is circulated between the first conveying path and the second conveying path via a first connecting port and a second connecting port. A developing unit, which is disposed opposite to the first transport path, is supplied with developer from the first transport path; as well as A third conveying component is disposed in a third conveying path, which recovers and conveys the developer remaining in the developing component back to the second conveying path. The axis of the second conveying component is positioned above the axis of the third conveying component in the direction of gravity.

2. The developing apparatus according to claim 1, wherein, A pre-defined partition is formed between the second conveyor path and the third conveyor path.

3. The developing apparatus according to claim 2, wherein, The upper end of the separating component is located above the imaginary straight line connecting the axis of the second conveying component and the axis of the third conveying component, in the direction of gravity.

4. The developing apparatus according to claim 1, wherein, A return prevention component is formed between the second transport path and the third transport path to prevent developer transported from the third transport path to the second transport path from returning to the third transport path.

5. The developing apparatus according to claim 4, wherein, The return prevention component is configured to allow developer to move from the third transport path to the second transport path, but prevent developer from moving from the second transport path to the third transport path.

6. An image forming apparatus comprising: The developing apparatus according to any one of claims 1 to 5; and A latent image holder positioned opposite the developing apparatus.

Images