Developing device and image forming apparatus

Abstract

To provide a developing apparatus and an image forming apparatus capable of preventing a developer from being transported to a support part that supports a second transportation member in the developing apparatus that has a first transportation member and the second transportation member arranged on a first transportation path and a second transportation path formed vertically in the gravity direction and discharge mechanism for discharging an excess developer in the first transportation path provided above in the gravity direction.SOLUTION: A developing apparatus 30 comprises: a first transportation member 58a and a second transportation member 58b arranged on a first transportation path 54a and a second transportation path 54b formed vertically in a gravity direction; discharge mechanism 72 that is provided on the first transportation path 58a provided above in the gravity direction and discharges an excessive developer; and a reverse direction wound part 80b that is wound in a direction opposite to a main wound part 76b formed to circulate a developer and is provided before a support part 74b for supporting the second transportation member 58b provided below in the gravity direction, the reverse direction wound part 80b transporting the developer to the discharge mechanism 72.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] Patent Document 1 discloses a developing container having a developing roll that transports toner to a developing area where an electrostatic latent image is developed into a toner image, a developing roll housing section that houses the developing roll, a first stirring chamber arranged diagonally below the developing roll housing section, and a second stirring chamber adjacent to the developing roll housing section and arranged above the first stirring chamber, a first stirring member that is housed in the first stirring chamber and transports the toner in the first stirring chamber while stirring it in a predetermined first transport direction, and a second stirring member that is housed in the second stirring chamber and transports the toner in the second stirring chamber in a second transport direction opposite to the first transport direction. and a communication passage that connects the downstream end of the first stirring chamber in the first transport direction to the upstream end of the second stirring chamber in the second transport direction in order to transport toner from the downstream end of the first stirring chamber in the first transport direction to the upstream end of the second stirring chamber in the second transport direction, the communication passage being on the side farthest from the developing roll with respect to the rotation axis of the first stirring member, and the portion of the communication passage that contacts the second stirring chamber and is located closest to the developing roll is formed vertically below the axis of the developing roll. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-175768 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention aims to provide a developing device and an image forming apparatus that can prevent developer from being transported to a support section that supports the second transport member in a developing device that has a first transport member and a second transport member arranged in a first transport path and a second transport path formed above and below in the direction of gravity, and that transports developer so as to circulate the developer between the first transport path and the second transport path, and has a discharge mechanism that discharges excess developer to the first transport path arranged above in the direction of gravity. [Means for solving the problem]

[0005] A developing device according to a first aspect of the present invention includes a first transport member and a second transport member that are disposed in a first transport path and a second transport path formed above and below in the direction of gravity, and that transport developer so as to circulate the developer between the first transport path and the second transport path; a discharge mechanism that is provided in the first transport path disposed above in the direction of gravity and that discharges excess developer; and a reverse winding portion that is wound in the opposite direction to a main winding portion formed to circulate developer, in front of a support portion that supports a second transport member disposed below in the direction of gravity, and the developer is transported to the discharge mechanism by the reverse winding portion.

[0006] In a developing device according to a second aspect of the present invention, a pressure applying portion that applies pressure to the developer transported in the reverse direction by the reverse winding portion is provided above the reverse winding portion in the gravitational direction.

[0007] In a third aspect of the developing device of the present invention, the reverse winding portion has a smaller diameter than the main winding portion.

[0008] In a developing device according to a fourth aspect of the present invention, an auxiliary winding portion wound in the same winding direction as the reverse-winding portion is provided between the support portion and the reverse-winding portion.

[0009] In a developing device according to a fifth aspect of the present invention, the auxiliary winding portion has a smaller diameter than the main winding portion.

[0010] In a sixth aspect of the present invention, in the developing device, the connecting portion is provided with a restricting portion that restricts movement of the opening / closing member in the opening direction.

[0011] In a seventh aspect of the present invention, a developing device has a lower surface above the auxiliary winding portion in the direction of gravity that is lower than the transport blocking portion in the direction of gravity, and an extended roof portion is formed extending from the transport blocking portion.

[0012] In an eighth aspect of the present invention, in the developing device, the discharge mechanism has a discharge passage through which excess developer is discharged via the second transport path.

[0013] In a ninth aspect of the present invention, in the developing device, the discharge passage is formed in front of the support portion.

[0014] An image forming apparatus of a tenth aspect of the present invention has a developing device and a developer holding member that holds developer developed by the developing device, and the developing device is arranged in a first transport path and a second transport path formed above and below in the direction of gravity, and has a first transport member and a second transport member that transport the developer so as to circulate the developer between the first transport path and the second transport path, a discharge mechanism provided in the first transport path arranged above in the direction of gravity and discharges excess developer, and a reverse winding portion wound in the opposite direction to a main winding portion formed to circulate the developer, in front of a support portion that supports a second transport member arranged below in the direction of gravity, and the developer is transported to the discharge mechanism by the reverse winding portion. Effect of the Invention

[0015] According to the developing device of the first aspect or the image forming apparatus of the tenth aspect of the present invention, in a developing device which is arranged in a first transport path and a second transport path formed above and below in the direction of gravity, and which has a first transport member and a second transport member which transport developer so as to circulate the developer between the first transport path and the second transport path, and which has a discharge mechanism which discharges excess developer to the first transport path arranged above in the direction of gravity, it is possible to prevent developer from being transported to a support portion which supports the second transport member.

[0016] According to the developing device of the second aspect, in addition to the effect of the first aspect, it is possible to apply a force for pushing up the developer into the first transport path.

[0017] According to the developing device of the third aspect, in addition to the effect of the first aspect, it is possible to prevent the developer from being returned to the main winding portion side in the second transport path.

[0018] According to the developing device of the fourth aspect, in addition to the effect of any one of the first to third aspects, the auxiliary winding portion can further prevent the developer from being transported to the support portion.

[0019] According to the developing device of the fifth aspect, in addition to the effect of the fourth aspect, the diameter of the transport path in the auxiliary winding portion can be made smaller than the diameter of the transport path in the main winding portion.

[0020] According to the developing device of the sixth aspect, in addition to the effect of the fourth aspect, the diameter of the transport path of the auxiliary winding part can be made smaller than the diameter of the transport path of the reverse-winding part.

[0021] According to the developing device of the seventh aspect, in addition to the effect of the fourth aspect, the force pushing up the developer by the extended roof portion is increased. According to the developing device of the eighth aspect, in addition to the effect of any one of the first to seventh aspects, the second transport path can be effectively used to discharge excess developer.

[0022] According to the developing device of the ninth aspect, in addition to the effect of the eighth aspect, it is possible to prevent excess developer from being transported to the supporting portion. [Brief description of the drawings]

[0023] [Figure 1] 1 is a side view illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view showing a developing device according to an embodiment of the present invention. [Diagram 3] 3 is a schematic cross-sectional view showing a flow of developer in a developing device according to an embodiment of the present invention. [Figure 4] 2 is a schematic diagram showing the vicinity of a discharge mechanism that discharges excess developer in a developing device according to an embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Next, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 shows an image forming apparatus 10 used in the embodiment of the present invention. The image forming apparatus 10 has an image forming apparatus main body 12 in which an image forming section 14, a transfer device 16, a fixing device 18, and a paper feed device 20 are arranged. In addition, a transport path 22 for transporting a recording medium such as paper is formed in the image forming apparatus main body 12.

[0025] The image forming section 14 employs an electrophotographic method and forms an image on a recording medium. The image forming section 14 has, for example, a plurality of, for example, four, image forming units 24. The four image forming units 24 form toner images of different colors, for example, yellow, magenta, cyan, and black.

[0026] The image forming unit 24 has a photoconductor drum 26. The photoconductor drum 26 is an example of an image carrier, and rotates while carrying a toner image to be transferred to a recording medium on its outer circumferential surface. The image forming unit 24 is also provided with a charging device 28 that charges the photoconductor drum 26, a developing device 30 that develops the charged latent image with toner, and a cleaning device 32 that cleans the photoconductor drum 26 after transfer. An optical writing device 48 that forms a latent image on the charged photoconductor drum 26 is also provided.

[0027] The transfer device 16 has an intermediate transfer belt 34. The toner images are primarily transferred from the photoconductor drums 26 onto the intermediate transfer belt 34 by a primary transfer member 36, and the primarily transferred toner images are secondarily transferred onto a recording medium by a secondary transfer member 38.

[0028] The intermediate transfer belt 34 is supported so as to be rotatable by a plurality of support members 40. In addition, a backup member 42 is provided opposite the secondary transfer member 38.

[0029] The fixing device 18 fixes the toner image transferred onto the recording medium onto the recording medium using, for example, heat and pressure.

[0030] The paper feeder 20 has a storage section 44 that stores recording media in a stacked state, and a delivery member 46 that delivers the recording media stored in the storage section 44 toward the transport path 22 .

[0031] The transport path 22 transports the recording medium from the paper feed device 20 to between the secondary transfer member 38 and the backup member 42, then transports the recording medium to the fixing device 18, and further transports the recording medium so that it is discharged outside the image forming device main body 12.

[0032] In the image forming apparatus 10 configured as described above, the toner images formed on the outer peripheral surfaces of the photosensitive drums 26 are primarily transferred to the intermediate transfer belt 34, the toner images primarily transferred to the intermediate transfer belt 34 are secondarily transferred to a recording medium, and the toner images secondarily transferred to the recording medium are fixed to the recording medium by the fixing device 18.

[0033] 2-4, development apparatus 30 is shown.

[0034] The developing device 30 is a two-component developing device that develops by stirring a developer made of a carrier and a toner and charging the toner.

[0035] The developing device 30 has a developing device main body 50, and a developer transport section 52 is provided in the developing device main body 50. In the developer transport section 52, for example, two transport paths 54a and 54b are formed so as to extend in the longitudinal direction of the developing device main body 50 and to overlap vertically in the direction of gravity. Here, the upper transport path 54a is the first transport path, and the lower transport path 54b is the second transport path. The transport paths 54a and 54b are partitioned in the vertical direction by a partition wall 56. The upper surface of the partition wall 56, which has an arc-shaped cross section, constitutes the lower surface of the first transport path 54a. The lower surface of the partition wall 56, which has an arc-shaped cross section, constitutes the upper surface of the second transport path 54b.

[0036] A first conveying member 58a is disposed on the first conveying path 54a, and a second conveying member 58b is disposed on the second conveying path 54b. The conveying members 58a, 58b are each composed of a rotating shaft 60a, 60b and a conveying portion 62a, 62b formed in a spiral shape around the rotating shaft 60a, 60b.

[0037] In addition, inside the developing device main body 50, a developing roll 64 is provided on the side of the first transport path 54a. This developing roll 64 faces the above-mentioned photosensitive drum 26, and moves the toner attached to the magnetic brush formed around the developing roll 64 to the latent image formed on the photosensitive drum 26. In addition, below the developing roll 64 of the developing device main body 50, a third transport path 66 is formed, and a third transport member 68 is provided in this third transport path 66. In addition, above the developing roll 64, a layer thickness regulating member 70 is provided to regulate the layer thickness of the developer.

[0038] In the above configuration, as shown in FIG. 3, the developer is first supplied to one end of the second transport path 54b, and is supplied to the first transport path 54a by the second transport member 58a near the other end of the second transport path 54b, and is transported to the vicinity of one end of the first transport path 54a by the first transport member 58a, and circulates between the first transport path 54a and the second transport path 54b. The first transport member 58a rotates clockwise in FIG. 2, transporting the developer from the first transport path 54a to the developing roll 64, and moves the toner attached to the magnetic brush formed around the developing roll 64 rotating counterclockwise to the latent image formed on the photosensitive drum 26. The developer not used for development by the developing roll 64 moves to the third transport path 66 and is returned to the second transport path 54b by the third transport member 68 rotating clockwise. The developer returned to the second transport path 54b is transported to the first transport path 54a by the second transport member 58a rotating in the clockwise direction.

[0039] Further, a discharge mechanism 72 is provided on the other end side of the first transport path 54a. The discharge mechanism 72 discharges excess developer from the other end of the first transport path 54a to the outside of the developing device 30, out of the developer circulating between the first transport path 54a and the second transport path 54b.

[0040] FIG. 4 shows the configuration of the discharge mechanism 72 and its surroundings.

[0041] The above-mentioned rotating shafts 60a, 60b are rotatably supported by supporting portions 74a, 74b formed at the ends of the developing device main body 50.

[0042] The first conveying section 62a has a first main winding section 76a, and the second conveying section 62b has a second main winding section 76b. At the end between the first main winding section 76a and the second main winding section 76b, a circulation port 78 is formed in the partition wall 56, and the wire is conveyed from the second conveying path 54b to the first conveying path 54a through the circulation port 78.

[0043] A first reverse winding portion 80a is formed on the rotating shaft 60a facing the end of the first main winding portion 76a. This first reverse winding portion 80a is wound, for example, once in the opposite direction to the first main winding portion 76a. A part of the developer circulated by this first reverse winding portion 80a is transported to the discharge mechanism 72 side. In addition, a return winding portion 82 is formed on the side opposite to the main winding portion of the first reverse winding portion 80a. This return winding portion 82 returns a part of the developer transported from the first reverse winding portion 80a to the first main winding portion 76a side.

[0044] The discharge mechanism 72 discharges excess developer that has climbed over a step 84 provided in the partition wall 56. A discharge winding portion 86 wound in the same direction as the first reverse-direction winding portion 80a is formed on the rotating shaft 60a above the step 84, and transports the developer that has climbed over the step 84 to a first discharge port 88a. The first discharge port 88a is formed in the partition wall 56, and excess developer is dropped through this first discharge port 88a to the second transport path 54b side.

[0045] A second reverse winding portion 80b is formed on the rotating shaft 60b so as to face the end of the second main winding portion 76b. The second reverse winding portion 80b is wound, for example, multiple times in the opposite direction to the second main winding portion 76b. The diameter of the second reverse winding portion 80b is smaller than the diameter of the second main winding portion 76b. A pressure applying portion 90 is formed so as to include the second reverse winding portion 80b from one end to the other end. The pressure applying portion 90 applies pressure to the developer returned by the second reverse winding portion 80b toward the second main winding portion 76b. As a result, the developer transported by the second main winding portion 76b and the developer returned by the second reverse winding portion 80b collide with each other at the bottom of the circulation port 78 of the second transport path 54b, and the developer is pushed up to the first transport path 54a through the circulation port 78. Further, the upper surface of the pressure applying portion 90 holds the developer that remains on the upper portion of the pressure applying portion 90 .

[0046] In addition, an auxiliary winding portion 92 is formed following the second main winding portion 76b. The winding direction of this auxiliary winding portion 92 is the same as that of the second reverse winding portion 80b, and is opposite to that of the second main winding portion 76b. In addition, the diameter of this auxiliary winding portion 92 is smaller than that of the second main winding portion 76b and the second reverse winding portion 80b. An extended roof portion 94 is formed around this second main winding portion 76b. The cross-sectional area of ​​this extended roof portion 94 is smaller than that of the second transport path 54b. Therefore, the amount of developer that enters around the auxiliary winding portion 92 is reduced, and even if the developer enters this portion, the rotation of the auxiliary winding portion 92 pushes the developer that has entered back to the second reverse winding portion 80b side, preventing the developer from reaching the support portion 74b.

[0047] A second discharge port 88b is formed in the lower part of the developing device main body 50 corresponding to the above-mentioned first discharge port 88. Excess developer is discharged to the outside of the developing device through this second discharge port 88b.

[0048] Incidentally, the excess developer passes through the second transport path 54b around the rotating shaft 62b near the support portion 74b, but no pressure acts on the excess developer passing through the second transport path 54b toward the support portion 74b, and so the excess developer is prevented from entering the support portion 74b. [Explanation of symbols]

[0049] 10 Image forming device 12 Image forming device main body 14 Image forming section 16 Transcription device 18 Fixing device 20 Paper feeder 22 Transport Path 24 Image forming unit 26 Photoconductor drum 28 Charging device 30 Developing device 32 Cleaning equipment 34 Intermediate transfer belt 36 Primary transfer member 38 Secondary transfer member 40 Support member 42 Backup parts 44 Storage area 46 Delivery member 48 Optical writing device 50 Developing device body 52 Developer transport section 54a First conveying path 54b Second conveying path 56 Partition Wall 58a First conveying member 58b second conveying member 60a, 60b Rotation shaft 62a, 62b Conveyor section 64 Developing Roll 66 Third Transport Path 68 Third conveying member 70 Layer thickness control member 72 Ejection mechanism 74a,74b Support part 76a First main coil 76b Second main coil 78 Circulation port 80a First reverse winding 80b Second reverse winding 82 Rewinding section 84 Step section 88a First outlet 88b Second outlet 90 Pressure applying section 92 Auxiliary winding section 94 Extended roof section

Claims

1. a first transport member and a second transport member that are disposed in a first transport path and a second transport path that are formed vertically in a gravity direction, and that transport the developer so as to circulate the developer between the first transport path and the second transport path; a discharge mechanism provided in the first transport path disposed above in the direction of gravity, for discharging excess developer; a reverse winding portion wound in a direction opposite to that of a main winding portion formed for circulating the developer, the reverse winding portion being wound in a direction opposite to that of a main winding portion formed in front of a support portion for supporting a second transport member disposed below in the direction of gravity; The developer is transported to the discharge mechanism by the reverse winding portion; Between the support portion and the reverse winding portion, an auxiliary winding portion is provided which is wound in the same winding direction as the reverse winding portion. A step is formed between the transport path around the auxiliary winding part and the second transport path so that the inner diameter of the transport path around the auxiliary winding part is smaller than the inner diameter of the second transport path, and an extension roof part extending from the step is formed above the auxiliary winding part in the gravity direction. Developing device.

2. 2. The developing device according to claim 1, further comprising a pressure applying portion disposed above said reverse winding portion in the direction of gravity, said pressure applying portion applying pressure to the developer transported in the reverse direction by said reverse winding portion.

3. 3. The developing device according to claim 1, wherein the reverse winding portion has a smaller diameter than the main winding portion.

4. 4. The developing device according to claim 1, wherein the auxiliary winding portion has a smaller diameter than the main winding portion.

5. 4. The developing device according to claim 1, wherein the auxiliary wound portion has a smaller diameter than the reverse wound portion.

6. 6. The developing device according to claim 1, wherein the discharge mechanism has a discharge passage through which excess developer is discharged via the second transport path.

7. 7. The developing device according to claim 6, wherein the discharge passage is formed in front of the support portion.

8. A developing device; a developer holding member that holds the developer developed by the developing device, The developing device is a first transport member and a second transport member that are disposed in a first transport path and a second transport path that are formed vertically in a gravity direction, and that transport the developer so as to circulate the developer between the first transport path and the second transport path; a discharge mechanism provided in the first transport path disposed above in the direction of gravity, for discharging excess developer; a reverse winding portion wound in a direction opposite to that of a main winding portion formed for circulating the developer, the reverse winding portion being wound in a direction opposite to that of a main winding portion formed in front of a support portion for supporting a second transport member disposed below in the direction of gravity; The developer is transported to the discharge mechanism by the reverse winding portion; Between the support portion and the reverse winding portion, an auxiliary winding portion is provided which is wound in the same winding direction as the reverse winding portion. A step is formed between the transport path around the auxiliary winding part and the second transport path so that the inner diameter of the transport path around the auxiliary winding part is smaller than the inner diameter of the second transport path, and an extension roof part extending from the step is formed above the auxiliary winding part in the gravity direction. Image forming device.

Images