Developing device and image forming apparatus

Abstract

The present application provides a developing device and an image forming apparatus. The developing device includes: a developing roller that holds toner on an outer periphery and rotates to develop a latent image on an image holding body; a regulating portion that regulates a thickness of the toner held by the developing roller; a first flow path forming portion that forms a first flow path that introduces external air between the regulating portion; a second flow path forming portion that forms a second flow path that connects with the first flow path in the vicinity of the regulating portion between the first flow path forming portion; and a suction unit that suctions air from the second flow path in a manner that causes the external air to flow from the first flow path toward the second flow path.

Description

TECHNICAL FIELD

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

[0002] A developing device is disclosed in Japanese Patent Application Publication No. 2008-39965, which forms a cover covering the upper side of a developer bearing body so that the front end thereof is positioned upstream of the developer conveying direction of a conveying pole that conveys the developer, forms a gap of uniform width between the developer bearing body and the cover, and forms an air flow in one direction in the gap. SUMMARY

[0003] A structure is considered as a developing device, which includes a restriction portion that restricts the thickness of toner held by a developing roller, and a flow path forming portion that forms a flow path that introduces outside air between the restriction portion and the flow path forming portion, and causes the outside air to flow through only the flow path, thereby attracting toner scattered from the developing roller. In this structure, sometimes the flow rate of the outside air flowing through the flow path becomes fast, and when the flow rate becomes fast, the toner easily adheres to the restriction portion by colliding with the restriction portion.

[0004] An object of the present disclosure is to suppress the adhesion of toner to the restriction portion, as compared with a structure that causes the outside air to flow through only the flow path that is formed between the restriction portion and the flow path forming portion and that introduces the outside air.

[0005] According to a first aspect of the present disclosure, there is provided a developing device including: a developing roller that holds toner on an outer periphery and rotates to develop a latent image on an image holding body; a restriction portion that restricts the thickness of toner held by the developing roller; a first flow path forming portion that forms a first flow path that introduces outside air between the restriction portion and the first flow path forming portion; a second flow path forming portion that forms a second flow path that connects with the first flow path in the vicinity of the restriction portion; and a suction unit that suctions air from the second flow path in a manner that causes the outside air to flow from the first flow path toward the second flow path.

[0006] According to a second aspect of the present disclosure, the first flow path causes the outside air to flow in a direction close to the developing roller, and the second flow path causes the outside air to flow in a direction away from the developing roller.

[0007] According to a third aspect of the present disclosure, the second flow path connects with the first flow path in a manner that turns back in the vicinity of the restriction portion with respect to the first flow path.

[0008] According to a fourth aspect of the present disclosure, a hole that introduces outside air is provided in a portion of the second flow path forming portion.

[0009] According to a fifth aspect of the present disclosure, the hole is provided in a portion of the second flow path forming portion in a manner elongated in an axial direction of the developing roller.

[0010] According to a sixth aspect of the present disclosure, an opening of the second flow path at a connection position of the first flow path and the second flow path is larger in size than an opening of the first flow path.

[0011] According to a seventh aspect of the present disclosure, the second flow path has a region in which a flow path width gradually narrows from the connection position.

[0012] According to an eighth aspect of the present disclosure, there is provided an image forming apparatus including: a developing roller that holds toner on an outer periphery and develops a latent image on an image holding body by rotation; a restricting portion that restricts a thickness of the toner held by the developing roller; a first flow path forming portion that forms a first flow path that introduces external air between the restricting portion; a second flow path forming portion that forms a second flow path that connects with the first flow path in the vicinity of the restricting portion between the first flow path forming portion; and a suction unit that suctions air from the second flow path in a manner that the external air flows from the first flow path toward the second flow path.

[0013] (EFFECTS)

[0014] According to the first aspect, compared with a structure in which only the first flow path is used to circulate the external air, it is possible to suppress the toner from adhering to the restricting portion.

[0015] According to the second aspect, compared with a structure in which the first flow path causes the external air to flow in a direction away from the developing roller and the second flow path causes the external air to flow in a direction approaching the developing roller, it is possible to suppress the toner from adhering to the restricting portion.

[0016] According to the third aspect, compared with a structure in which the circulation direction of the first flow path has an angle of, for example, about 90 degrees with respect to the circulation direction of the second flow path, it is possible to save space to form the first flow path and the second flow path.

[0017] According to the fourth aspect, compared with a structure in which the second flow path forming portion does not have a hole, it is possible to suppress the toner from adhering to the second flow path forming portion.

[0018] According to the fifth aspect, compared with a structure in which the hole is short in the axial direction of the developing roller, it is possible to suppress the toner from adhering to the second flow path forming portion from one end side to the other end side in the axial direction.

[0019] According to the sixth aspect, compared with a structure in which the size of the opening of the second flow path at the connection position with the first flow path is smaller than the size of the opening of the first flow path, it is possible to suppress the adhesion of toner to the first flow path forming portion and the second flow path forming portion in the vicinity of the opening of the second flow path.

[0020] According to the seventh aspect, compared with a structure in which the second flow path has a region in which the flow path width gradually widens from the connection position, it is possible to suppress the adhesion of toner to the first flow path forming portion and the second flow path forming portion in the vicinity of the opening of the second flow path.

[0021] According to the eighth aspect, compared with a structure in which only the first flow path is used to circulate external air, it is possible to suppress the adhesion of toner to the restriction portion. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a schematic view showing the structure of the image forming apparatus of the present embodiment.

[0023] Figure 2 is a side sectional view showing the structure of the developing apparatus of the present embodiment.

[0024] Figure 3 is a side sectional view showing a part of the developing apparatus of the present embodiment in an enlarged manner.

[0025] Figure 4 is a schematic view showing the introduction hole formed in the second flow path forming portion of the present embodiment.

[0026] Figure 5 is a side sectional view showing the flow rate in the second flow path in the structure shown in Figure 3

[0027] Figure 6 is a side sectional view showing the first flow path forming portion formed in a tapered shape in the modified example.

[0028] Figure 7 is a side sectional view showing the second flow path forming portion not having the introduction hole in the modified example. DETAILED DESCRIPTION

[0029] Hereinafter, an example of an embodiment of the present disclosure will be described with reference to the drawings.

[0030] (Image forming apparatus 10)

[0031] The structure of the image forming apparatus 10 of the present embodiment will be described. Figure 1 is a schematic view showing the structure of the image forming apparatus 10 of the present embodiment.

[0032] Figure 1 ​The illustrated image forming apparatus 10 is an example of an image forming apparatus that forms an image on a recording medium. Specifically, the image forming apparatus 10 is an electrophotographic image forming apparatus that forms a toner image (an example of an image) on a recording medium P. More specifically, the image forming apparatus 10 includes an image forming section 14 and a fixing apparatus 16. Hereinafter, each section (the image forming section 14 and the fixing apparatus 16) of the image forming apparatus 10 will be described.

[0033] (Image forming section 14)

[0034] The image forming section 14 has a function of forming a toner image on the recording medium P. Specifically, the image forming section 14 has a toner image forming section 22 and a transfer apparatus 17.

[0035] (Toner image forming section 22)

[0036] Figure 1 The illustrated toner image forming section 22 is provided in plurality so as to form a toner image in accordance with each color. In the present embodiment, the toner image forming section 22 is provided in a total of four colors of yellow (Y), magenta (M), cyan (C), and black (K). Figure 1 The (Y), (M), (C), and (K) illustrated indicate constituent parts corresponding to each of the above colors.

[0037] In addition, the toner image forming section 22 of each color is configured to be the same except for the toner used, and thus the toner image forming section 22 of each color will be described below with the toner image forming section 22 (K) of black color as a representative. Figure 1 In the following description, the same reference numerals are used for the same parts of the toner image forming section 22 (K) of black color.

[0038] Specifically, the toner image forming section 22 of each color has a photosensitive drum 32 (a photoreceptor) that rotates in one direction (for example, the counterclockwise direction in the drawing). Figure 1 In addition, the toner image forming section 22 of each color has a charger 23, an exposure apparatus 36, and a developing apparatus 38.

[0039] In the toner image forming section 22 of each color, the charger 23 charges the photosensitive drum 32. Also, the exposure apparatus 36 exposes the photosensitive drum 32 charged by the charger 23 to form an electrostatic latent image on the photosensitive drum 32. In addition, the developing apparatus 38 develops the electrostatic latent image formed on the photosensitive drum 32 by the exposure apparatus 36 to form a toner image.

[0040] The photosensitive drum 32 rotates while holding the electrostatic latent image formed as described above on the outer periphery thereof, and the electrostatic latent image is transferred to the developing apparatus 38. The photosensitive drum 32 is an example of an image holding body. The electrostatic latent image is an example of a latent image. In addition, the specific structure of the developing apparatus 38 will be described later.

[0041] (transfer device 17)

[0042] Figure 1 The transfer device 17 shown is a device that transfers the toner image formed by the toner image forming section 22 to the recording medium P. Specifically, the transfer device 17 superimposes the toner images of the respective color photosensitive drums 32 and transfers the superimposed toner image to the recording medium P once. Specifically, as shown in Figure 1 The transfer device 17 shown includes the transfer belt 24, a primary transfer roller 26, and a secondary transfer roller 28.

[0043] The primary transfer roller 26 is a roller that transfers the toner image on the photosensitive drum 32 of each color to the transfer belt 24 at a primary transfer position T1 between the photosensitive drum 32 and the primary transfer roller 26. In the present embodiment, the toner image formed on the photosensitive drum 32 is transferred to the transfer belt 24 at the primary transfer position T1 by applying a primary transfer electric field between the primary transfer roller 26 and the photosensitive drum 32.

[0044] The transfer belt 24 transfers the toner image from the photosensitive drum 32 of each color to the outer circumferential surface. Specifically, the transfer belt 24 is configured as follows. As shown in Figure 1 The transfer belt 24 is annular and assumes a posture by being wound around a plurality of rollers 42.

[0045] For example, the transfer belt 24 is rotationally driven in the direction of the arrow A by a driving roller 42D among the plurality of rollers 42 being rotationally driven by a driving section (omitted from the drawing). In addition, the transfer belt 24 is rotationally driven in the direction of the arrow B by a driven roller 42D among the plurality of rollers 42 being rotationally driven by a driven section (omitted from the drawing). Figure 1 The roller 42B shown is an opposing roller 42B that opposes the secondary transfer roller 28.

[0046] The secondary transfer roller 28 transfers the toner image transferred to the transfer belt 24 to the recording medium P at a secondary transfer position T2 between the opposing roller 42B and the secondary transfer roller 28. In the present embodiment, the toner image transferred to the transfer belt 24 is transferred to the recording medium P at the secondary transfer position T2 by applying a secondary transfer electric field between the opposing roller 42B and the secondary transfer roller 28.

[0047] (fixing device 16)

[0048] Figure 1 The fixing device 16 shown fixes the toner image transferred to the recording medium P by the secondary transfer roller 28 to the recording medium P. Specifically, as shown in Figure 1As shown, the fixing device 16 includes a heating roller 16A as a heating member and a pressure roller 16B as a pressure member. In the fixing device 16, the heating roller 16A and the pressure roller 16B heat and pressurize the recording medium P, thereby fixing the toner image formed on the recording medium P to the recording medium P.

[0049] (Developing device 38)

[0050] Next, the structure of the developing device 38 will be described. Figure 2 It is a side sectional view showing the structure of the developing device 38 . Figure 3 This is an enlarged side cross-sectional view of a portion of the developing device 38. In the following description, the direction indicated by arrow LH in the figure refers to the left of the developing device 38, and the direction indicated by arrow RH refers to the right of the developing device 38. The left and right directions are defined for ease of explanation, and the structure of the developing device 38 is not limited to these directions. In this embodiment, the side on which the photosensitive drum 32 is disposed relative to the developing roller 64 (described later) is the right side, and the side opposite to the side on which the photosensitive drum 32 is disposed is the left side.

[0051] like Figure 2 As shown, the developing device 38 includes a developing device main body 60 , a flow path forming frame 70 as an example of a flow path forming member that forms a flow path, and a suction device 59 as an example of a suction unit.

[0052] (Developing Device Main Body 60)

[0053] like Figure 2 As shown, the developing device main body 60 includes a frame 62 , a developing roller 64 , a regulator 66 as an example of a regulating portion, and a pair of conveying members 67 and 68 .

[0054] The frame 62 functions as a container for developer G containing toner and magnetic carrier. The frame 62 has an opening 69 that opens toward the photosensitive drum 32. Furthermore, the frame 62 includes at least a side wall 62A (first wall), an upper wall 62B (second wall), and an inclined wall 62C (third wall). The side wall 62A extends vertically in a side sectional view. In the side sectional view, the upper wall 62B extends rightward from the upper end of the side wall 62A. In the side sectional view, the inclined wall 62C extends diagonally downward to the right from the right end of the upper wall 62B.

[0055] The frame 62 has a width greater than that of the developing roller 64 in the axial direction of the developing roller 64. Therefore, both ends of the frame 62 in the width direction extend outward in the axial direction relative to both ends of the developing roller 64.

[0056] The developing roller 64 is a roller that holds a developer G containing toner on its outer periphery and develops the electrostatic latent image on the photosensitive drum 32 by rotating. In other words, the developing roller 64 transports the developer G to the photosensitive drum 32 and supplies the developer G to the photosensitive drum 32 by rotating while holding the developer G on its outer periphery.

[0057] Specifically, the developing roller 64 uses magnetic force to hold the magnetic carrier contained in the developer G accommodated in the frame 62, forms a magnetic brush of the developer G on the outer peripheral surface, and transports the developer G to a position opposing the photosensitive drum 32. The toner of the developer G transported to the opposing position by the developing roller 64 is supplied to the electrostatic latent image formed on the photosensitive drum 32, and the electrostatic latent image is visualized as a toner image.

[0058] The developing roller 64 is provided in the frame 62 so as to partially be exposed from the opening 69 of the frame 62. The developing roller 64 is disposed so as to face the photosensitive drum 32.

[0059] The trimmer 66 functions as a limiting unit for controlling the thickness of the toner held by the developing roller 64. Specifically, the trimmer 66 contacts the developer G transported by the developing roller 64 toward a position opposite the photosensitive drum 32, thereby limiting the thickness of the developer G layer (i.e., the amount of developer). The trimmer 66 is constructed from a non-magnetic metal plate such as stainless steel. In a side cross-sectional view, the trimmer 66 is attached to the inclined wall 62C of the frame 62, extending obliquely downward and to the right from the inclined wall 62C toward the developing roller 64. Specifically, the trimmer 66 is secured to the inclined wall 62C, for example, by screws.

[0060] like Figure 2 As shown, the transport members 67 and 68 are arranged on the lower side relative to the developing roller 64 in the interior of the frame 62 and on the opposite side (left side) of the developing roller 64 from the photosensitive drum 32 .

[0061] The conveying member 67 is provided on one side of the axial direction of the developing roller 64 (for example, from Figure 2 The developer G is transported in a direction from the front side of the paper to the rear side. The transport member 68 is arranged along the other side of the axial direction of the developing roller 64 (for example, from the front side to the rear side). Figure 2 The developer G is transported from the rear side of the paper surface to the front side. As a result, the developer G inside the frame 62 is stirred and circulated therein. The developer G transported by the transport member 68 is held on the outer periphery of the developing roller 64.

[0062] (Flow Path Forming Frame 70)

[0063] Figure 3The flow path forming frame 70 shown is a frame that forms a flow path for recovering toner scattered from the developing roller 64. Specifically, as shown Figure 3 The flow path forming frame 70 shown forms the first flow path 51 and the second flow path 52 as the flow path.

[0064] The first flow path 51 is a flow path that introduces outside air. Specifically, the first flow path 51 causes outside air to flow in a direction toward the developing roller 64. In other words, the first flow path 51 causes outside air to pass in a direction toward the adjuster 66. More specifically, the first flow path 51 has an introduction port 51E, an upstream portion 51A, a middle upstream portion 51B, a middle downstream portion 51C, and a downstream portion 51D.

[0065] The introduction port 51E is an introduction port that introduces outside air, which is open on the left side. In addition, the outside air is air introduced from the outside of the flow path forming frame 70. Specifically, the outside air is air introduced from the outside of the developing device 38.

[0066] In the side cross-sectional view, the upstream portion 51A extends to the right side from the introduction port 51E. In the side cross-sectional view, the middle upstream portion 51B extends upward from the downstream end (i.e., the right end) of the upstream portion 51A. In the side cross-sectional view, the middle downstream portion 51C extends to the right side from the downstream end (i.e., the upper end) of the middle upstream portion 51B. In the side cross-sectional view, the downstream portion 51D extends to the right obliquely downward side from the downstream end (i.e., the right end) of the middle downstream portion 51C. The downstream portion 51D causes outside air to flow in a direction toward the developing roller 64.

[0067] The second flow path 52 is a flow path that connects with the first flow path 51 in the vicinity of the adjuster 66. Specifically, the second flow path 52 connects with the first flow path 51 in such a manner as to turn back in the vicinity of the adjuster 66 with respect to the first flow path 51. In other words, the second flow path 52 causes outside air to pass in a direction opposite to the passing direction of the first flow path 51. That is, the passing direction of the first flow path 51 and the passing direction of the second flow path 52 change by 180 degrees. Further, the second flow path 52 is arranged on the upper side of the first flow path 51 in overlapping relation with the first flow path 51 via the first flow path forming portion 71.

[0068] In addition, the second flow path 52 causes outside air to flow in a direction away from the developing roller 64. Also, the second flow path 52 has an upstream portion 52A, a middle upstream portion 52B, a downstream portion 52C, and a discharge port 52E.

[0069] Here, the connection structure in which the first flow path 51 and the second flow path 52 connect in the vicinity of the adjuster 66 refers to a structure that connects at a position opposite the adjuster 66 in the present embodiment. More specifically, the connection structure refers to a structure that connects within the range of imaginary lines 66A, 66B that extend vertically from one end and the other end of the plate-shaped adjuster 66 in the side cross-sectional view.

[0070] The upstream end of the upstream portion 52A is connected to the downstream end of the first flow path 51 (i.e., the downstream end of the downstream portion 51D). The upstream portion 52A extends obliquely upward to the left in the side cross-sectional view. In other words, the upstream portion 52A causes the outside air to flow in a direction away from the developing roller 64. Furthermore, the upstream portion 52A flows in a direction opposite to the downstream portion 51D.

[0071] In the side cross-sectional view, the midstream portion 52B extends to the left from the downstream end (i.e., the upper end) of the upstream portion 52A. In the side cross-sectional view, the downstream portion 52C extends downward from the downstream end (i.e., the left end) of the midstream portion 52B. The discharge port 52E is a port that discharges the outside air, and opens toward the rear side of the paper face (one side in the axial direction of the developing roller 64) of the downstream end portion of the downstream portion 52C. Figure 3

[0072] Specifically, the flow path forming frame 70 has a first flow path forming portion 71, a second flow path forming portion 72, and a third flow path forming portion 73. This flow path forming frame 70 is formed separately from the frame body 62. Furthermore, the flow path forming frame 70 has a width longer than the developing roller 64 along the axial direction of the developing roller 64. Also, both ends of the flow path forming frame 70 in the width direction protrude further outward than both ends of the developing roller 64 in the axial direction. In other words, the flow path forming frame 70 has a width equivalent to that of the frame body 62.

[0073] In addition, the first flow path forming portion 71, the second flow path forming portion 72, and the third flow path forming portion 73 are integrally formed in a plate shape. In the side cross-sectional view, the third flow path forming portion 73 extends to the left side from the middle portion in the vertical direction of the side wall 62A of the frame body 62.

[0074] The first flow path forming portion 71 is a portion that forms the first flow path 51 between the adjusting member 66. Specifically, the first flow path forming portion 71 forms the first flow path 51 between the third flow path forming portion 73, a portion of the frame body 62 (specifically, the side wall 62A, the upper wall 62B, and the inclined wall 62C), and the adjusting member 66.

[0075] More specifically, the first flow path forming portion 71 has a first portion 71A, a second portion 71B, a third portion 71C, and a fourth portion 71D.

[0076] In the side cross-sectional view, the first portion 71A extends in the left-right direction opposite the third flow path forming portion 73. The first portion 71A forms the upstream portion 51A of the first flow path 51 between the third flow path forming portion 73. Furthermore, the first portion 71A forms the guide inlet 51E of the first flow path 51 between the left end thereof and the left end of the third flow path forming portion 73.

[0077] ​The second portion 71B opposes the side wall 62A of the frame 62 in the side cross-sectional view and extends upward from the right end of the first portion 71A. The second portion 71B forms the middle-stream portion 51B of the first flow path 51 together with the side wall 62A of the frame 62.

[0078] The third portion 71C opposes the upper wall 62B of the frame 62 in the side cross-sectional view and extends to the right side from the upper end of the second portion 71B. The third portion 71C forms the stream portion 51C between the third portion 71C and the upper wall 62B of the frame 62.

[0079] The fourth portion 71D opposes the inclined wall 62C of the frame 62 and the adjuster 66 in the side cross-sectional view and extends to the right obliquely downward side from the right end of the third portion 71C. The fourth portion 71D forms the downstream portion 51D of the first flow path 51 between the inclined wall 62C of the frame 62 and the adjuster 66. As described above, the first flow path 51 is formed by the first flow path forming portion 71, the third flow path forming portion 73, a portion of the frame 62 (specifically, the side wall 62A, the upper wall 62B, and the inclined wall 62C), and the adjuster 66.

[0080] The second flow path forming portion 72 is a portion that forms the second flow path 52 between the first flow path forming portion 71. Specifically, the second flow path forming portion 72 has a first portion 72A, a second portion 72B, and a third portion 72C.

[0081] The first portion 72A opposes the fourth portion 71D of the first flow path forming portion 71 in the side cross-sectional view and extends to the left obliquely upward side from the outer peripheral side of the photosensitive drum 32. The first portion 72A forms the upstream portion 52A of the second flow path 52 between the fourth portion 71D of the first flow path forming portion 71. Further, a gap 72G is provided between the first portion 72A and the photosensitive drum 32.

[0082] The second portion 72B opposes the third portion 71C of the first flow path forming portion 71 in the side cross-sectional view and extends to the left side from the left end of the first portion 72A. The second portion 72B forms the middle-stream portion 52B of the second flow path 52 between the third portion 71C of the first flow path forming portion 71.

[0083] The third portion 72C opposes the second portion 71B of the first flow path forming portion 71 in the side cross-sectional view and extends to the downward side from the left end of the second portion 72B. The third portion 72C forms the downstream portion 52C of the second flow path 52 between the second portion 71B of the first flow path forming portion 71. As described above, the second flow path 52 is formed by the first flow path forming portion 71 and the second flow path forming portion 72. Therefore, in the present embodiment, the forming portion of the first flow path 51 and the forming portion of the second flow path 52 are common in one portion (the first flow path forming portion 71) and different in other portions.

[0084] The size of the opening 52G of the first flow path 51 at the connection point between the first flow path 51 and the second flow path 52 is larger than the size of the opening 51G of the second flow path 52. That is, at the connection point between the first flow path 51 and the second flow path 52, the size of the opening 52G between the first flow path forming portion 71 and the second flow path forming portion 72 is larger than the size of the opening 51G between the first flow path forming portion 71 and the regulator 66.

[0085] In the side cross-sectional view, the opening 51G is an opening at the shortest distance (see the two-dot chain line) from the lower end of the first flow path forming portion 71 to the regulator 66. In the side cross-sectional view, the opening 52G is an opening at the shortest distance (see the two-dot chain line) from the lower end of the first flow path forming portion 71 to the second flow path forming portion 72.

[0086] Furthermore, in a side cross-sectional view, the second flow path 52 has a region where the flow path width gradually narrows from the connection position. Specifically, the flow path width of the upstream portion 52A of the second flow path 52 gradually narrows toward the downstream side (ie, the upper side).

[0087] Furthermore, a portion of the second flow path forming portion 72 is provided with an inlet hole 74 (an example of a hole) for introducing outside air. Specifically, the inlet hole 74 is formed above the lower end of the first portion 72A of the second flow path forming portion 72. Therefore, the inlet hole 74 can be said to be an inlet for outside air, provided separately from the gap 72G.

[0088] like Figure 4 As shown, the inlet hole 74 is provided in the first portion 72A of the second flow path forming portion 72, extending in the axial direction of the developing roller 64. Specifically, the inlet hole 74 is longer in the axial direction than in the direction along the surface of the second flow path forming portion 72 intersecting the axial direction of the developing roller 64 (specifically, perpendicular to the axial direction). More specifically, the inlet hole 74 is formed into a rectangular shape with a longer axial length. In this embodiment, a plurality of inlet holes 74 (specifically, three, for example) are provided in the axial direction of the developing roller 64 relative to the first portion 72A of the second flow path forming portion 72.

[0089] Furthermore, side walls 79 are provided at both ends in the width direction of the first flow path forming portion 71 and the second flow path forming portion 72. Thus, both ends in the width direction of the first flow path 51 and the second flow path 52 are closed except for the discharge port 52E.

[0090] (Suction device 59)

[0091] The suction device 59 is a device that suctions air from the second flow path 52 in a manner such that external air is drawn from the first flow path 51 toward the second flow path 52. The suction device 59 is disposed at the downstream end of the second flow path 52 (specifically, the discharge port 52E). In the suction device 59, air suctioned from the second flow path 52 is discharged to the outside of the flow path forming frame 70 through the discharge port 52E.

[0092] As the suction device 59, for example, a suction device using a radial fan that blows air in a radial direction, a centrifugal fan that blows air in a centrifugal direction, or the like can be applied.

[0093] (Action of the Present Embodiment)

[0094] Next, the action of the present embodiment will be described.

[0095] According to the developing device 38 of the present embodiment, as shown in Figure 2 the developing roller 64 holds the developer G accommodated in the frame 62 at the outer periphery thereof and rotates to convey the developer G to the photosensitive drum 32, thereby developing an electrostatic latent image on the photosensitive drum 32.

[0096] During the developing of the electrostatic latent image on the photosensitive drum 32 by the developing roller 64, scattering of toner (so-called toner cloud) can occur. For example, toner scatters from the portion Al between the developing roller 64 and the regulator 66, the portion Bl between the developing roller 64 and the photosensitive drum 32, and the portions Al to Bl on the outer periphery of the developing roller 64.

[0097] Also, in the present embodiment, the suction device 59 suctions air from the second flow path 52 in a manner such that external air is drawn from the first flow path 51 toward the second flow path 52. Thereby, external air is introduced from the introduction port 51E, and the external air passes through the upstream portion 51A, the middle upstream portion 51B, the middle downstream portion 51C, and the downstream portion 51D of the first flow path 51 in this order.

[0098] Further, by the suction of the suction device 59, external air is introduced from the introduction hole 74 and the gap 72G. This external air merges with the external air that has passed through the first flow path 51, passes through the second flow path 52 in the order of the upstream portion 52A, the middle upstream portion 52B, and the downstream portion 52C, and is discharged from the discharge port 52E. Thereby, the scattered toner (hereinafter referred to as scattered toner) is recovered (i.e., discharged).

[0099] Here, in the present embodiment, the first flow path 51 formed between the first flow path forming portion 71 and the regulator 66 and the second flow path 52 formed between the first flow path forming portion 71 and the second flow path forming portion 72 are connected near the regulator 66.

[0100] Thus, by connecting the first flow path 51 and the second flow path 52 as different flow paths in the vicinity of the adjuster 66, the flow rate of the outside air in the vicinity of the adjuster 66 can be reduced compared to a structure in which only the first flow path 51 is used to circulate the outside air (hereinafter referred to as a first structure). As a result, the collision energy of the toner colliding with the adjuster 66 is reduced compared to the first structure, and the toner is suppressed from adhering to the adjuster 66. Thus, the toner adhering to the adjuster 66 can be suppressed from accumulating and falling onto the photosensitive drum 32.

[0101] Further, in the present embodiment, the first flow path 51 causes the outside air to flow in a direction approaching the developing roller 64. Thus, the outside air flows from the adjuster 66 side to the developing roller 64 side, thereby suppressing the flying toner generated on the developing roller 64 side from heading toward the adjuster 66. Also, the second flow path 52 allows the outside air to flow in a direction away from the developing roller 64. Thus, the flying toner generated on the developing roller 64 side is likely to head toward the second flow path 52 rather than the first flow path 51. Thereby, compared to a structure in which the first flow path 51 causes the outside air to flow in a direction away from the developing roller 64 and the second flow path 52 causes the outside air to flow in a direction approaching the developing roller 64, the toner is suppressed from adhering to the adjuster 66.

[0102] Further, in the present embodiment, the second flow path 52 is connected to the first flow path 51 in a manner of being folded back in the vicinity of the adjuster 66. Thus, compared to a structure in which the flow direction of the first flow path 51 has an angle of, for example, 90 degrees or so with respect to the flow direction of the second flow path 52, the first flow path 51 and the second flow path 52 can be formed in a space-saving manner.

[0103] Further, in the present embodiment, the second flow path 52 is connected to the first flow path 51 in a manner of being folded back in the vicinity of the adjuster 66. Thus, compared to a structure in which the flow direction of the first flow path 51 has an angle of, for example, 90 degrees or so with respect to the flow direction of the second flow path 52, the first flow path 51 and the second flow path 52 can be formed in a space-saving manner.

[0104] Further, by providing the introduction hole 74 in the second flow path formation portion 72, the flow rate of the outside air introduced from the gap 72G between the lower end of the second flow path formation portion 72 and the photosensitive drum 32 is also reduced. As a result, compared to the second structure, the collision energy of the toner colliding with the second flow path formation portion 72 is reduced, and the toner is suppressed from adhering to the second flow path formation portion 72. Further, the second structure can also be said to be a structure in which the outside air is introduced only from the gap 72G between the lower end of the second flow path formation portion 72 and the photosensitive drum 32.

[0105] In addition, in this embodiment, the outside air from the second flow path forming portion 72 side introduced from the introduction hole 74 and the outside air from the first flow path forming portion 71 side that has passed through the first flow path 51 merge and flow into the second flow path 52. Figure 5 As shown, in the second flow path 52, the flow velocity (see arrow X2) at a position close to the first and second flow path forming sections 71 and 72 is slower than the flow velocity (see arrow X1) at a position farther from the center of the first and second flow path forming sections 71 and 72. Therefore, the collision energy of toner colliding with the first and second flow path forming sections 71 and 72 in the second flow path 52 is reduced, thereby suppressing toner adhesion to the first and second flow path forming sections 71 and 72 in the second flow path 52.

[0106] Furthermore, in the embodiment, Figure 4 As shown, the introduction hole 74 is provided in the first portion 72A of the second flow path forming portion 72 so as to extend in the axial direction of the developing roller 64 .

[0107] Therefore, compared with a structure in which the introduction hole 74 is short in the axial direction of the developing roller 64 , adhesion of toner to the second flow path forming portion 72 is suppressed from one end side to the other end side in the axial direction.

[0108] In addition, in this embodiment, Figure 3 As shown, the size of the opening 52G of the first flow path 51 at the connection position between the first flow path 51 and the second flow path 52 is larger than the size of the opening 51G of the second flow path 52 .

[0109] Therefore, compared to a configuration in which the size of opening 52G is smaller than that of opening 51G (hereinafter referred to as a third configuration), the flow rate of the external air near opening 52G can be reduced. As a result, compared to the third configuration, the collision energy of the toner colliding with the first and second flow path forming portions 71 and 72 near opening 52G is reduced, and toner adhesion to the first and second flow path forming portions 71 and 72 near opening 52G is suppressed.

[0110] Furthermore, the second flow path 52 includes a region where the flow path width gradually narrows from the connection point between the first flow path 51 and the second flow path 52. Therefore, compared to a configuration in which the second flow path 52 includes a region where the flow path width gradually widens from the connection point (hereinafter referred to as the fourth configuration), the flow velocity of the external air near the opening 52G can be reduced. As a result, compared to the fourth configuration, the collision energy of toner colliding with the first and second flow path-forming portions 71 and 72 near the opening 52G is reduced, and toner adhesion to the first and second flow path-forming portions 71 and 72 near the opening 52G is suppressed.

[0111] As described above, in the present embodiment, for example, the flow rate of the external air on the surface of the adjuster 66, the surface of the first portion 72A of the second flow path forming portion 72 in the second flow path 52, and the surface of the fourth portion 71D of the first flow path forming portion 71 is in a range of 3 m / s or more and 1 m / s or less. Here, if the flow rate of the external air is less than 0.3 m / s, the deposition of toner is likely to occur; if the flow rate of the external air exceeds 1 m / s, the adhesion of toner is likely to occur. In the present embodiment, the flow rate of the external air on the surface of the adjuster 66, the surface of the first portion 72A of the second flow path forming portion 72 in the second flow path 52, and the surface of the fourth portion 71D of the first flow path forming portion 71 is in a range of 0.3 m / s or more and 1 m / s or less, and the adhesion of toner to each portion is suppressed.

[0112] (Variants)

[0113] In addition, in the present embodiment, the second flow path 52 is connected to the first flow path 51 in a manner of being bent around the adjuster 66, but is not limited thereto. The angle of the flow-through direction of the first flow path 51 with respect to the flow-through direction of the second flow path 52 may, for example, be an angle in a range of 90 degrees or more and less than 180 degrees. In this case, for example, as shown in FIG. 17, a structure in which the fourth portion 71D of the first flow path forming portion 71 is formed in a tapered shape in a manner of being thickened on the upper side in a side cross-sectional view can be cited. Figure 6

[0114] In addition, in the above-described embodiment, the introduction hole 74 (an example of a hole) is provided at a portion of the second flow path forming portion 72, but is not limited thereto. For example, as shown in FIG. 18, a structure in which the introduction hole 74 is not provided at the second flow path forming portion 72 can also be adopted. Figure 7

[0115] Further, in the present embodiment, the introduction hole 74 is provided at the first portion 72A of the second flow path forming portion 72 in a manner of being elongated along the axial direction of the developing roller 64, but is not limited thereto. For example, the introduction hole 74 can be a structure that is shorter in the axial direction of the developing roller 64.

[0116] In addition, in the present embodiment, the size of the opening 52G of the first flow path 51 at the connection position of the first flow path 51 and the second flow path 52 is larger than the size of the opening 51G of the second flow path 52, but is not limited thereto. For example, the size of the opening 52G can be smaller than the size of the opening 51G.

[0117] In addition, in the present embodiment, the second flow path 52 has a region in which the flow path width gradually narrows from the connection position of the first flow path 51 and the second flow path 52, but is not limited thereto. For example, the second flow path 52 can have a region in which the flow path width gradually widens from the connection position.

[0118] ​​Also in the present embodiment, the flow path forming frame 70 and the frame body 62 are formed separately, but are not limited thereto. For example, the flow path forming frame 70 and the frame body 62 can also be formed integrally.

[0119] Also, the first flow path forming portion 71, the second flow path forming portion 72, and the third flow path forming portion 73 are formed in a plate shape, but are not limited thereto. For example, the first flow path forming portion 71, the second flow path forming portion 72, and the third flow path forming portion 73 can have different thicknesses in part.

[0120] Also, in the present embodiment, the first flow path forming portion 71, the second flow path forming portion 72, and the third flow path forming portion 73 are formed integrally, but are not limited thereto. The first flow path forming portion 71, the second flow path forming portion 72, and the third flow path forming portion 73 can also be formed separately. Also, each of the first flow path forming portion 71, the second flow path forming portion 72, and the third flow path forming portion 73 can be formed separately.

[0121] In the present embodiment, a plurality of (specifically, for example, three) introduction holes 74 are provided along the axial direction of the developing roller 64 with respect to the first portion 72A of the second flow path forming portion 72, but are not limited thereto. For example, the introduction holes 74 can also be constituted by a single hole.

[0122] The present disclosure is not limited to the above-described embodiments, and various modifications, changes, and improvements can be made within the scope of the gist thereof. For example, the above-described modification examples can also be appropriately combined in multiple to constitute.

Claims

1. A developing device comprising a developing device body, a flow path forming member for forming a flow path, and a suction unit, The developing device main body comprises: frame; a developing roller that holds toner on its periphery and develops the latent image on the image holding member by rotating; a restriction portion that restricts the thickness of the toner held by the developing roller, The flow path forming member comprises: a first flow path forming portion forming a first flow path for introducing external air between the first flow path forming portion and the restriction portion; a second flow path forming portion that forms a second flow path with the first flow path forming portion, the second flow path being connected to the first flow path near the restriction portion; and a third flow path forming portion extending leftward from a vertically intermediate portion of a side wall of the frame of the developing device main body; The first flow path forming portion forms the first flow path between the first flow path forming portion, the third flow path forming portion, a portion of the frame, and the restricting portion. The suction unit sucks air from the second flow path so that the external air flows from the first flow path toward the second flow path. A hole for introducing external air is provided in a portion of the second flow path forming portion that is above the lower end of the first portion. The first portion of the second flow path forming portion extends from the outer peripheral side of the photosensitive drum to the upper left side with a gap between the first portion and the photosensitive drum. The second flow path has a region where the flow path width gradually narrows from a connection position between the first flow path and the second flow path.

2. The developing device according to claim 1, wherein The first flow path allows the external air to flow toward the developing roller. The second flow path allows the external air to flow in a direction away from the developing roller.

3. The developing device according to claim 2, wherein: The second flow path is connected to the first flow path so as to bend back relative to the first flow path near the restriction portion.

4. The developing device according to claim 1, wherein The hole is provided in a portion of the second flow path forming portion so as to extend in the axial direction of the developing roller.

5. The developing device according to any one of claims 1 to 4, wherein: The size of the opening of the second flow path at a connection position between the first flow path and the second flow path is larger than the size of the opening of the first flow path.

6. An image forming apparatus comprising a developing device body, a flow path forming member forming a flow path, and a suction unit, The developing device main body comprises: frame; a developing roller that holds toner on its periphery and develops the latent image on the image holding member by rotating; a restriction portion that restricts the thickness of the toner held by the developing roller, The flow path forming member comprises: a first flow path forming portion forming a first flow path for introducing external air between the first flow path forming portion and the restriction portion; a second flow path forming portion that forms a second flow path with the first flow path forming portion, the second flow path being connected to the first flow path near the restriction portion; and a third flow path forming portion extending leftward from a vertically intermediate portion of a side wall of the frame of the developing device main body; The first flow path forming portion forms the first flow path between the first flow path forming portion, the third flow path forming portion, a portion of the frame, and the restricting portion. The suction unit sucks air from the second flow path so that the external air flows from the first flow path toward the second flow path. A hole for introducing external air is provided in a portion of the second flow path forming portion that is above the lower end of the first portion. The first portion of the second flow path forming portion extends from the outer peripheral side of the photosensitive drum to the upper left side with a gap between the first portion and the photosensitive drum. The second flow path has a region where the flow path width gradually narrows from a connection position between the first flow path and the second flow path.

Images