Image forming apparatus including air flow passage to cleaner of photoreceptor unit

Abstract

SOLUTION: An image forming apparatus of an aspect comprises: a developing unit 20 that has a storage area 20A for storing developer and a conveyance area 20B for supplying developer to the storage area; a photoreceptor unit 40 that has a photoreceptor 41 forming a toner image with toner in the developer, and a cleaner 45 removing excess toner remaining on a surface of the photoreceptor; a first air flow passage 71 that connects the storage area and the cleaner with each other; and a second air flow passage 72 that connects the cleaner and the conveyance area with each other.EFFECT: Since air is supplied to a cleaner 45 from a storage area 20A of a developing unit 20 through a first air flow passage 71, toner can be efficiently conveyed inside the cleaner 45, and attachment of toner to an inner face of a toner conveyance path can be prevented.SELECTED DRAWING: Figure 2

Description

[Background technology]

[0001] The image forming apparatus includes a developing unit that stirs developer, and a photoconductor unit having a photoconductor that forms a toner image from the toner in the developer. The developing unit has a developing roller that holds the stirred developer. The photoconductor unit has a cleaner that removes excess toner remaining on the surface of the photoconductor. [Brief description of the drawings]

[0002] [Figure 1] FIG. 1 is a schematic diagram of an imaging device that can be used to implement various examples disclosed herein. [Diagram 2] FIG. 2 is a schematic cross-sectional view of an exemplary developer unit and photoreceptor unit. [Diagram 3] FIG. 3 is a perspective view of an exemplary developer unit and photoreceptor unit. [Figure 4] FIG. 4 is a perspective view showing the developing unit and the photosensitive unit as viewed from the opposite side to that in FIG. [Diagram 5] FIG. 5 is a schematic diagram showing a toner transport path, transport members, and blades of the cleaner of the photosensitive unit. [Figure 6] FIG. 6 is a graph showing experimental results of toner transport performance in an image forming apparatus according to an embodiment having a first air flow path and a second air flow path, and an image forming apparatus according to a comparative example not having the first air flow path and the second air flow path. [Figure 7] FIG. 7 is a graph showing the internal pressure of an image forming apparatus according to an embodiment having a first air flow path and a second air flow path, and the internal pressure of an image forming apparatus according to a comparative example not having the first air flow path and the second air flow path. [Figure 8] FIG. 8 is a graph showing an example of the relationship between the internal pressure of an image forming apparatus and the excessive discharge ratio of developer. [Figure 9] FIG. 9 is a schematic cross-sectional view of a development unit and a photoconductor unit according to a modified example. [Figure 10]FIG. 10 is a diagram showing a conveying member according to a modified example. [Figure 11] FIG. 11 is a diagram illustrating an example of a first air flow path connected to the toner transport path in FIG. [Figure 12] FIG. 12 is a perspective view showing a developing unit and a photoconductor unit according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0003] Various examples of image forming apparatuses according to the present disclosure will be described below with reference to the drawings. In the description of the drawings, the same or corresponding elements are designated by the same reference numerals, and duplicated descriptions are omitted as appropriate. In addition, the drawings may be partially simplified or exaggerated for ease of understanding, and the dimensional ratios and angles are not limited to those shown in the drawings.

[0004] The image forming apparatus according to the present disclosure includes a first air flow path connecting a storage area of ​​the developing unit and a cleaner of the photoconductor unit, and a second air flow path connecting the cleaner and a transport area of ​​the developing unit. The developing unit has a developing roller that holds developer in the storage area, and the internal pressure of the storage area becomes higher than the internal pressure of the cleaner as the developing roller holds the developer while rotating. In the exemplary image forming apparatus, air is supplied from the storage area to the cleaner via the first air flow path using the pressure difference between the internal pressure of the storage area and the internal pressure of the cleaner. A specific example of this image forming apparatus will be described below.

[0005] FIG. 1 is a diagram that shows an example of an image forming apparatus. The image forming apparatus 1 shown in FIG. 1 is an apparatus that forms a color image using each of the colors cyan, magenta, yellow, and black. The image forming apparatus 1 includes a conveying device 10 that conveys a paper 5 that is a print medium, developing units 20C, 20M, 20Y, and 20K that develop electrostatic latent images (hereinafter, when there is no need to distinguish between the individual components, they will be referred to as "developing units 20"), and a transfer device 30 that transfers toner images of each color onto the paper 5. Furthermore, the image forming apparatus 1 includes photoconductor units 40C, 40M, 40Y, and 40K (hereinafter, when there is no need to distinguish between the individual components, they will be referred to as "photoconductor 41" and "photoconductor unit 40") having photoconductors 41C, 41M, 41Y, and 41K that are examples of image carriers, a fixing device 50 that fixes the laminated toner image onto the paper 5, and a discharge device 60 that discharges the paper 5.

[0006] The conveying device 10 conveys paper 5, which is a print medium on which an image is formed, on a conveying path 12. The paper 5 is stored in a stack in a cassette 7, and is picked up and conveyed by a paper feed roller 11. The conveying device 10 causes the paper 5 to reach the transfer area 13 via the conveying path 12 at the timing when the toner image to be transferred to the paper 5 reaches the transfer area 13.

[0007] Developing units 20C, 20M, 20Y, and 20K are provided for each color. Each developing unit 20 includes a developing roller 21 that develops toner onto a photoconductor 41. In the developing unit 20, a two-component developer containing toner and carrier is used as the developer. In the developing unit 20, the toner and carrier are adjusted to a desired mixing ratio. When the toner and carrier are mixed and stirred, the toner is uniformly dispersed, and a developer with an optimal charge is prepared.

[0008] In the developing unit 20 using a two-component developer, for example, a trickle discharge method is adopted to extend the life of the developer. The trickle discharge method is a method in which new carrier is replenished to the developing unit 20 when toner is replenished, and old developer is discharged from the developing unit 20 to the outside. The trickle discharge method is also called a trickle development method or ADR (Auto Developer Refill). In this disclosure, "developer" refers to a developer containing both toner and carrier.

[0009] In the developing unit 20, the developing roller 21 carries the developer. Then, when the developer is transported to a developing area facing the photoconductor 41 by the rotation of the developing roller 21, the toner contained in the developer carried by the developing roller 21 moves to the electrostatic latent image formed on the surface of the photoconductor 41, and the electrostatic latent image is developed.

[0010] The transfer device 30 transports the toner image formed by the developing unit 20 to a transfer area 13 where the toner image is secondarily transferred onto the paper 5. The transfer device 30 includes a transfer belt 31, which is an endless belt onto which a toner image is primarily transferred from a rotating photoconductor 41, a suspension roller 34 that stretches the transfer belt 31, idler rollers 35 and 36, a drive roller 37 that drives the transfer belt 31, primary transfer rollers 32C, 32M, 32Y, and 32K that hold the transfer belt 31 together with the photoconductors 41C, 41M, 41Y, and 41K, and a secondary transfer roller 33 that holds the transfer belt 31 together with the drive roller 37.

[0011] The photoconductors 41C, 41M, 41Y, and 41K rotate. The photoconductor 41 is called an electrostatic latent image carrier or a photoconductor drum. The photoconductors 41C, 41M, 41Y, and 41K are provided for each color. The photoconductors 41 are lined up along the moving direction of the transfer belt 31. The photoconductor unit 40 includes, for example, a photoconductor 41, a charging device 42, and a cleaner 45. The developing unit 20, the charging device 42, the exposure unit 43, and the cleaner 45 are provided at positions facing the surface of the photoconductor 41.

[0012] The charging device 42 is, for example, a charging roller that contacts the photoreceptor 41. The charging device 42 uniformly charges the surface of the photoreceptor 41 to a predetermined potential. The exposure unit 43 exposes the surface of the photoreceptor 41 charged by the charging device 42 according to an image to be formed on the paper 5. As a result, the potential of the portion of the surface of the photoreceptor 41 exposed by the exposure unit 43 changes, and an electrostatic latent image is formed on the surface of the photoreceptor 41.

[0013] The developing units 20C, 20M, 20Y, and 20K are opposed to the toner tanks 18C, 18M, 18Y, and 18K, respectively. The toner tanks 18C, 18M, 18Y, and 18K (hereinafter, referred to as "toner tanks 18" when there is no need to distinguish between individual components) contain cyan, magenta, yellow, and black toners, respectively. Toner is supplied from the toner tanks 18 to the developing unit 20. The developing unit 20 develops the electrostatic latent image formed on the photoconductor 41 with the toner supplied from the toner tanks 18 to generate a toner image. The cleaner 45 collects toner remaining on the photoconductor 41. The configuration of the cleaner 45 will be described in detail later.

[0014] The fixing device 50 fixes the toner image, which has been secondarily transferred from the transfer belt 31 to the paper 5, onto the paper 5 by passing the paper 5 through a fixing nip area where heat and pressure are applied. The fixing device 50 includes a heating roller 52 that heats the paper 5, and a pressure roller 54 that presses and rotates the heating roller 52. The fixing nip area is provided between the heating roller 52 and the pressure roller 54. The discharge device 60 includes discharge rollers 62, 64 that discharge the paper 5, on which the toner image has been fixed by the fixing device 50, to the outside of the image forming apparatus 1.

[0015] Next, a printing process by the image forming apparatus 1 will be described. When an image signal of an image to be recorded is input to the image forming apparatus 1, the control unit of the image forming apparatus 1 rotates the paper feed roller 11 to pick up and transport the paper 5 stacked in the cassette 7. Then, the charging device 42 uniformly charges the surface of the photoconductor 41 to a predetermined potential (charging process). After that, based on the input image signal, the exposure unit 43 irradiates the surface of the photoconductor 41 with laser light to form an electrostatic latent image (exposure process).

[0016] The developing unit 20 develops the electrostatic latent image formed on the surface of the photoreceptor 41 to form a toner image on the surface of the photoreceptor 41 (developing process). The toner image is primarily transferred from the photoreceptor 41 to the transfer belt 31 in a region where the photoreceptor 41 and the transfer belt 31 face each other (transfer process). The toner images formed on the photoreceptor 41 are sequentially stacked on the transfer belt 31 to form one stacked toner image. The stacked toner image is secondarily transferred to the paper 5 transported from the transport device 10 in a transfer region 13 where the drive roller 37 and the secondary transfer roller 33 face each other.

[0017] The paper 5 onto which the laminated toner image has been transferred is transported to the fixing device 50. The fixing device 50 applies heat and pressure to the paper 5 in the fixing nip area between the heating roller 52 and the pressure roller 54 as the paper 5 passes through the fixing nip area. The fixing device 50 fixes the laminated toner image to the paper 5 by this heating and pressure (fixing process). The paper 5 is then discharged to the outside of the image forming apparatus 1 by discharge rollers 62, 64.

[0018] FIG. 2 is a diagram showing the developing unit 20 and the photoconductor unit 40. As shown in FIG. 2, the developing unit 20 has a storage area 20A that stores a developer and a transport area 20B that transports the developer to the storage area 20A. The storage area 20A is provided above the transport area 20B. In addition to the developing roller 21 described above, the developing unit 20 includes a supply auger 22 that supplies developer to the developing roller 21, and an admix auger 23 that extends parallel to the supply auger 22 and is disposed below the supply auger 22. The supply auger 22 and the admix auger 23 correspond to stirring and transporting members that stir and transport the developer.

[0019] The developing roller 21 and the supply auger 22 are housed in a storage area 20A of the developing unit 20. The admix auger 23 is housed in a transport area 20B of the developing unit 20. The developing unit 20 has a wall 24 that separates the storage area 20A and the transport area 20B, and an opening located at the end of the wall 24 in the axial direction of the supply auger 22 (the direction perpendicular to the paper surface of FIG. 2), and the developer in the transport area 20B moves to the storage area 20A through this opening.

[0020] However, since the developer transported by the admix auger 23 often accumulates below the opening, high airtightness is ensured between the storage area 20A and the transport area 20B. The developer stirred by the supply auger 22 in the storage area 20A is held by the developing roller 21. The developing roller 21 faces the photoconductor 41 of the photoconductor unit 40, and the developer held by the developing roller 21 moves to the surface of the photoconductor 41.

[0021] 3 is a perspective view of the developing unit 20 and the photoconductor unit 40 as viewed from the developing unit 20 side. As shown in FIG. 2 and FIG. 3, the supply auger 22 and the admix auger 23 extend along the longitudinal direction D1 of the developing unit 20 (in FIG. 2, a direction perpendicular to the paper surface of FIG. 2).

[0022] The image forming apparatus 1 has a first air flow path 71 extending from the storage area 20A of the developing unit 20 to the cleaner 45. The first air flow path 71 connects the storage area 20A and the cleaner 45. The first air flow path 71 supplies air from the storage area 20A to the cleaner 45 by a pressure difference between the storage area 20A and the cleaner 45. The first air flow path 71 has an inlet 71b above the developing roller 21. The inlet 71b is located at an end 25 of the developing unit 20 on the opposite side to the photoconductor unit 40 as seen from the developing roller 21. The pressure difference between the storage area 20A and the cleaner 45 is generated by the developing roller 21 holding the developer while rotating.

[0023] When the developing roller 21 rotates, air is drawn into the storage area 20A by the developer carried on the surface of the developing roller 21, and the air pressure in the storage area 20A increases. More specifically, the air is drawn into the storage area 20A by the standing developer brushes carried on the surface of the developing roller 21, and the air pressure in the storage area 20A increases. As the air pressure in the storage area 20A increases, the air in the storage area 20A is supplied to the cleaner 45 via the first air flow path 71.

[0024] 4 is a perspective view of the developing unit 20 and the photosensitive unit 40 as viewed from the photosensitive unit 40 side. As shown in Fig. 3 and Fig. 4, the photosensitive unit 40 extends along the longitudinal direction D1 of the developing unit 20. A first air flow path 71 extending from the accommodation area 20A of the developing unit 20 extends, for example, to the cleaner 45, bypassing above the photosensitive unit 40.

[0025] As an example, the first air flow path 71 is configured by a tube. However, the first air flow path 71 may be something other than a tube, and the shape and material of the first air flow path 71 are not particularly limited. In addition, the first air flow path 71 does not have to detour above the photoconductor unit 40, and may, for example, detour around the end 40b in the longitudinal direction D1 of the photoconductor unit 40 and extend to the cleaner 45. In this way, the position of the first air flow path 71 is also not particularly limited.

[0026] 5 is a diagram showing a schematic diagram of the cleaner 45. As shown in Fig. 4 and Fig. 5, the cleaner 45 has a cylindrical toner transport path 46, a transport member 47 that transports the toner inside the toner transport path 46, and a blade 48 that is located above the toner transport path 46 and scrapes off the toner from the surface of the photoconductor 41. For example, the toner scraped off from the surface of the photoconductor 41 by the blade 48 falls into the toner transport path 46. The toner transport path 46, the transport member 47, and the blade 48 extend along the longitudinal direction D1.

[0027] The transport member 47 is, for example, an auger having a rod-shaped shaft portion and a blade portion formed in a spiral shape on the shaft portion. The cleaner 45 further has a drive member 49 that rotates the transport member 47. The drive member 49 includes, for example, a motor and a gear that rotate the transport member 47. The transport member 47 is rotated by the drive member 49, and transports the toner inside the toner transport path 46 along a transport direction D2 by the rotation. The transport direction D2 is, for example, a direction extending along the longitudinal direction D1 of the developing unit 20.

[0028] The toner transport path 46 has a first end 46b including one end in the transport direction D2 and a second end 46c including the other end in the transport direction D2, and the transport member 47 transports the toner from the first end 46b toward the second end 46c. The first end 46b is located outside the transport direction D2 of an end 48b of the blade 48 in the transport direction D2. An outlet 71c of the first air flow path 71 is located outside the end 48b of the blade 48 in the transport direction D2 of the toner transport path 46.

[0029] The image forming apparatus 1 has a second air flow passage 72 that connects the cleaner 45 and the transport region 20B of the developing unit 20. For example, the second air flow passage 72 extends from the toner transport path 46 of the cleaner 45 to the outside of the cleaner 45. The second air flow passage 72 has an inlet 72b at the second end 46c of the toner transport path 46. For example, the inlet 72b is located at an upper part of the toner transport path 46. Toner enters the inlet 72b of the second air flow passage 72 together with air.

[0030] For example, the developing unit 20 has a toner supply port 26 that supplies toner to the transport area 20B. The toner supply port 26 is connected to the transport area 20B. The second air flow path 72 has, for example, an outlet 72c at the toner supply port 26. The second air flow path 72 supplies toner from the toner supply port 26 to the transport area 20B together with air supplied from the storage area 20A of the developing unit 20, which is at high pressure, to the cleaner 45 via the first air flow path 71. As an example, the internal pressure of the storage area 20A of the developing unit 20 is 20.3 Pa, while the internal pressure of the second air flow path 72 is 14.3 Pa. Due to this pressure difference, air and toner are supplied from the cleaner 45 to the transport area 20B via the second air flow path 72.

[0031] For example, the second air flow path 72 extending from the toner transport path 46 has an outlet 72c in the transport area 20B of the developing unit 20 located diagonally below the toner transport path 46. As an example, the second air flow path 72 is configured by a tube. However, the second air flow path 72 may be something other than a tube, and the shape, material, and position of the second air flow path 72 are not particularly limited.

[0032] Next, a description will be given of the effects and advantages obtained from the image forming apparatus 1. As described above, in the image forming apparatus 1, the developing unit 20 has a storage area 20A that stores the developer, and a transport area 20B that supplies the developer to the storage area 20A. The photoconductor unit 40 includes a photoconductor 41 that forms a toner image from the toner in the developer, and a cleaner 45 that removes excess toner remaining on the surface of the photoconductor 41.

[0033] Furthermore, the image forming apparatus 1 includes a first air flow path 71 connecting the storage area 20A and the cleaner 45, and a second air flow path 72 connecting the cleaner 45 and the transport area 20B. Since air is supplied from the storage area 20A of the developing unit 20 to the cleaner 45 via the first air flow path 71, the toner can be efficiently transported inside the cleaner 45, and adhesion of the toner to the inner surface of the toner transport path 46, etc. can be suppressed.

[0034] Since the toner is transported in a dispersed form in the cleaner 45 by the air from the first air flow path 71, the generation of toner agglomerates inside the cleaner 45 can be suppressed. Therefore, the occurrence of poor image quality on the paper 5 caused by toner agglomerates can be reduced. Furthermore, in the image forming apparatus 1, the pressure difference between the storage area 20A and the cleaner 45 is used to supply air from the storage area 20A to the cleaner 45, making it possible to eliminate the need for an air transport device such as a pump. Therefore, the size of the image forming apparatus 1 can be suppressed.

[0035] The pressure difference is generated by the developer held by the developing roller 21 while the developing roller 21 rotates. Therefore, the pressure increase in the storage area 20A of the developing unit 20 caused by the rotation of the developing roller 21 can be utilized for transporting the toner in the cleaner 45. The transport of the toner collected in the cleaner 45 can be assisted by the air from the first air flow path 71, so that the toner can be transported stably in the cleaner 45.

[0036] 6 is a graph showing the results of measuring the toner transportability of the image forming apparatus 1 of the embodiment having the first air flow path 71 and the second air flow path 72, and the toner transportability of the image forming apparatus of the comparative example not having the first air flow path 71 and the second air flow path 72. The vertical axis of the graph in FIG. 6 indicates the amount of toner discharged from the cleaner 45 in 5 minutes. As shown in FIG. 6, the amount of toner discharged in 5 minutes in the image forming apparatus of the comparative example was 1.09 g, whereas the amount of toner discharged in 5 minutes in the image forming apparatus 1 of the embodiment was 1.75 g. Thus, it was found that the image forming apparatus 1 of the embodiment can transport and discharge about 60% more toner than the image forming apparatus of the comparative example.

[0037] Fig. 7 is a graph showing the results of measuring the internal pressure of the developing unit 20 in the image forming apparatus 1 of the embodiment and the internal pressure of the developing unit in the image forming apparatus of the comparative example. As shown in Fig. 7, the internal pressure of the developing unit in the image forming apparatus of the comparative example was about 30 Pa, whereas the internal pressure of the developing unit 20 in the image forming apparatus 1 of the embodiment was about 21 Pa. Thus, it was found that the image forming apparatus 1 can suppress the pressure rise inside the developing unit 20 by about 30%.

[0038] FIG. 8 is a graph showing the relationship between the internal pressure of the developing unit 20 employing ADR (trickle discharge method) and the excess discharge ratio of developer from the developing unit 20. The horizontal axis of the graph in FIG. 8 indicates the internal pressure of the developing unit 20, and the vertical axis of the graph in FIG. 8 indicates the excess discharge ratio. The unit of the excess discharge ratio is g / kPV, and indicates the amount of developer excessively discharged from the developing unit when 1000 sheets of paper are printed. As shown in FIG. 7 and FIG. 8, in the image forming apparatus 1 of the embodiment, the internal pressure of the developing unit can be reduced by about 30% compared to the image forming apparatus of the comparative example, so that the excess discharge of developer in ADR can be suppressed.

[0039] As described above, the developing unit 20 has the developing roller 21 that is located in the storage area 20A and transports the developer, and the first air flow path 71 may have the inlet 71b above the developing roller 21. In this case, the distance from the inlet 71b to the cleaner 45 can be shortened, so that air in the storage area 20A can be efficiently supplied to the cleaner 45. The inlet 71b of the first air flow path 71 may be located at the end 25 of the developing unit 20 on the opposite side to the photoconductor unit 40 as viewed from the developing roller 21. In this case, the empty space inside the developing unit 20 can be effectively used as the inlet 71b to the first air flow path 71.

[0040] As described above, the cleaner 45 may have the toner transport path 46 having a cylindrical shape and the transport member 47 that transports the toner inside the toner transport path 46. The transport member 47 may transport the toner from the first end 46b to the second end 46c of the toner transport path 46 along the transport direction D2 extending along the axis of the toner transport path 46. The first air flow path 71 may have an outlet 71c at the first end 46b of the toner transport path 46. In this case, since the outlet 71c is provided at the upstream end of the toner transport path 46, air from the first air flow path 71 can be supplied to the entire toner transport path 46 from the first end 46b to the second end 46c. Therefore, the transportability of the toner inside the toner transport path 46 can be further improved.

[0041] The cleaner 45 has a blade 48 that scrapes off toner from the surface of the photoreceptor 41 above the toner transport path 46, and the blade 48 may extend along the transport direction D2. The outlet 71c of the first air flow path 71 may be located outside the end 48b of the blade 48 in the transport direction D2 of the toner transport path 46. In this case, air can be sent from the outlet 71c of the first air flow path 71 to the entire area where the toner enters the toner transport path 46 from the blade 48. This can further improve the toner transportability in the cleaner 45.

[0042] The second air flow passage 72 may have an inlet 72b at the second end 46c of the toner transport path 46, and the second air flow passage 72 supplies the toner transported in the toner transport path 46 together with air to the transport region 20B of the developing unit 20. In this case, the toner transported in the toner transport path 46 is returned to the developing unit 20, so that the toner can be effectively utilized.

[0043] Next, an image forming apparatus according to a modified example will be described. Fig. 9 is a schematic cross-sectional view of a developing unit 20D and a photoconductor unit 40 of an image forming apparatus according to a modified example. A part of the configuration of the image forming apparatus according to the modified example overlaps with a part of the configuration of the image forming apparatus 1 described above, and therefore the overlapping description will be omitted as appropriate.

[0044] The developing unit 20D includes a filter 27 that discharges air in the transport area 20B to the outside of the developing unit 20D. The filter 27 is disposed at a position facing the admix auger 23. The air in the transport area 20B is discharged to the outside of the developing unit 20D via the filter 27. The filter 27 is disposed, for example, on the opposite side of the admix auger 23 from the outlet 72c of the second air flow path 72. As described above, in the developing unit 20D including the filter 27, air can be discharged from the filter 27 to the outside of the developing unit 20D, and the pressure in the transport area 20B can be made closer to atmospheric pressure, so that the efficiency of air transport in the first air flow path 71 and the second air flow path 72 can be improved.

[0045] As described above, the cleaner 45 of the image forming apparatus 1 includes the conveying member 47 which is an auger. However, as shown in FIG. 10, the cleaner 45 according to a modified example may include the conveying member 47A which is a coil spring. For example, the conveying member 47A is formed by spirally winding a square piece of material having a rectangular cross section. The inside of the conveying member 47A which is a coil spring serves as a passage for air. Therefore, when the conveying member 47A which is a coil spring is provided, the conveying performance of the air and toner in the cleaner 45 can be further improved.

[0046] Fig. 11 is a cross-sectional view showing a toner transport path 46A and a first air flow path 71A according to a modified example. As shown in Fig. 11, the first air flow path 71A has a bent portion 73. For example, the first air flow path 71A is bent at the bent portion 73 from the width direction D3 of the toner transport path 46A to the transport direction D2.

[0047] For example, the first air flow path 71A has a straightening member 74 disposed at the bent portion 73. The straightening member 74 is disposed, for example, on the inner wall surface of the bent portion 73 in the first air flow path 71A. By providing the straightening member 74 in the first air flow path 71A, even when the first air flow path 71A has the bent portion 73, air can flow smoothly in the first air flow path 71A.

[0048] An outlet 71d of the first air flow path 71A communicates with the internal space of the toner transport path 46A. At the outlet 71d, air A flows along an inclined direction D4 inclined with respect to the transport direction D2. An angle θ of the inclined direction D4 with respect to the transport direction D2 is greater than 0° and less than 90°. The angle θ may be 10° or more and 80° or less, or may be 20° or more and 60° or less, and may be changed as appropriate.

[0049] In this case, for example, the outlet 71d is formed between a first wall portion 46f of the toner transport path 46A extending along the transport direction D2 and a second wall portion 71f extending along the inclined direction D4. In this way, when the air A flows along the inclined direction D4 at the outlet 71d, the air A can be more smoothly introduced into the toner transport path 46A, so that the toner transportability in the cleaner 45 can be further improved.

[0050] Fig. 12 is a perspective view showing a photoconductor unit 40 according to a modified example. As shown in Fig. 12, in the photoconductor unit 40 according to the modified example, the toner transport path 46 has an outlet 46d at a second end 46c for discharging the toner transported by the transport member 47. The cleaner 45 has a waste toner collection container 45b for collecting the toner discharged from the outlet 46d. The outlet 46d is located at the bottom of the toner transport path 46. The waste toner collection container 45b is disposed below the outlet 46d and collects the toner discharged from the outlet 46d.

[0051] Light toner with a low specific gravity enters the inlet 72b of the second air flow path 72 together with air. Toner that does not flow into the inlet 72b is transported to the outlet 46d and discharged from the outlet 46d to the waste toner collection container 45b. The outlet 46d and the waste toner collection container 45b are located outside the inlet 72b of the second air flow path 72 in the transport direction D2 of the toner transport path 46. Therefore, it is possible to allow only light toner with a low specific gravity to flow into the second air flow path 72 from the inlet 72b.

[0052] As described above, the cleaner 45 may include a waste toner collecting container 45b for collecting toner that did not flow into the inlet 72b of the second air flow path 72, and the inlet 72b of the second air flow path 72 may be located at the upper part of the toner transport path 46. The developing unit 20 may have a toner supply port 26 for supplying toner to the transport region 20B, and the second air flow path 72 may have an outlet 72c at the toner supply port 26. In this case, only toner with a low specific gravity is allowed to flow into the second air flow path 72, while carriers with a high specific gravity and the like can be discharged from the toner transport path 46 to the waste toner collecting container 45b. Then, the toner with a low specific gravity can be supplied to the transport region 20B via the second air flow path 72 and the toner supply port 26. Therefore, the toner with a low specific gravity can be effectively used.

[0053] It should be understood that not all aspects, advantages, and features described herein are necessarily achieved or included in any one particular example and embodiment. Indeed, while various examples have been described and illustrated herein, it should be apparent that other examples can be modified in arrangement and detail. For example, the image forming apparatus may be one in which a single component developer is used, or one which forms black and white images. Accordingly, we claim all modifications and variations that fall within the spirit and scope of the subject matter claimed herein.

Claims

1. a developing unit having a developer storage area and a transport area that supplies the developer to the developer storage area; a photoconductor unit including a photoconductor for forming a toner image from the toner in the developer and a cleaner for removing excess toner remaining on the surface of the photoconductor; a first air flow passage connecting the storage area and the cleaner; a second air flow path connecting the cleaner and the transfer area; Equipped with Image forming device.

2. the developing unit includes a developing roller that is located in the storage area and transports the developer; the first air flow passage has an inlet above the developer roller; The image forming apparatus according to claim 1 .

3. In the first air flow path, air is supplied from the storage area to the cleaner due to a pressure difference between the storage area and the cleaner. The image forming apparatus according to claim 2 .

4. the inlet of the first air flow passage is located at an end of the developing unit on an opposite side to the photoconductor unit from the developing roller; The image forming apparatus according to claim 2 .

5. the cleaner has a cylindrical toner transport path and a transport member that transports toner inside the toner transport path, the transport member transports the toner from a first end to a second end of the toner transport path along a transport direction extending along an axis of the toner transport path, the first air flow passage has an outlet at the first end of the toner transport path; The image forming apparatus according to claim 1 .

6. the conveying member being a coil spring; The image forming apparatus according to claim 5 .

7. the cleaner has a blade disposed above the toner transport path for scraping off the toner from the surface of the photoconductor; The blade extends along the conveying direction, the outlet of the first air flow path is located outside the end of the blade in the transport direction of the toner transport path; The image forming apparatus according to claim 5 .

8. At the outlet of the first air flow path, air flows along an inclined direction inclined with respect to the transport direction, the angle of the inclination direction with respect to the conveying direction is greater than 0° and less than 90°; The image forming apparatus according to claim 5 .

9. The first air flow path has a bent portion and a straightening member disposed at the bent portion. The image forming apparatus according to claim 1 .

10. the second air flow passage has an inlet at the second end of the toner transport path; The image forming apparatus according to claim 5 .

11. the second air flow passage supplies the toner transported in the toner transport path together with air to the transport area of ​​the developing unit; The image forming apparatus according to claim 5 .

12. the cleaner includes a waste toner collection container that collects toner that has not flowed into the inlet of the second air flow path; The image forming apparatus according to claim 1 .

13. an inlet of the second air flow path is located above the toner transport path; The image forming apparatus according to claim 5 .

14. the developing unit has a toner supply port for supplying toner to the transport area, the second air flow passage has an outlet at the toner supply port; The image forming apparatus according to claim 1 .

15. the developing unit includes a filter that exhausts air from the transport region to the outside of the developing unit; The image forming apparatus according to claim 1 .

Images