JP5482403B2 - Developing device and image forming apparatus - Google Patents

Description

  The present invention relates to a developing device and an image forming apparatus, and more particularly to a developing device and an image forming apparatus that develop a toner image on a photoreceptor.

  As a conventional developing device, for example, a developing device described in Patent Document 1 is known. FIG. 7 is a configuration diagram of the developing device 500 described in Patent Document 1.

  As shown in FIG. 7, the developing device 500 includes a developing roller 502, a scattered toner prevention plate 504, and a toner suction duct 506. The developing roller 502 develops a toner image on a photoconductor (not shown). The scattered toner prevention plate 504 is a member provided so as to face the photoreceptor in order to prevent toner from scattering from the developing roller 502. The toner suction duct 506 sucks the scattered toner through the suction hole 508. According to the developing device 500 as described above, toner scattering can be suppressed, and deterioration of image quality can be prevented.

  However, as described below, the developing device 500 cannot sufficiently suppress toner scattering. More specifically, the developing roller 502 has a carrying area that carries toner and a non-carrying area that does not carry toner. When the developing device 500 is driven, toner scattering is likely to occur in the non-carrying region. Therefore, as shown in FIG. 7, the suction hole 508 is provided in the vicinity of the end of the developing roller 502 provided with the non-carrying region.

  However, a part of the toner scattered in the non-carrying region is deposited on the scattered toner prevention plate 504 without being sucked by the toner suction duct 506 through the suction hole 508. If the amount of toner accumulated on the scattering toner prevention plate 504 increases, the toner may fall on the photosensitive drum or the developing roller 502. As a result, in the image forming apparatus to which the developing device 500 is applied, the image quality is degraded.

JP 2009-115990 A

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a developing device and an image forming apparatus that can suppress a decrease in image quality.

A developing device according to a first aspect of the present invention is a developing device that is used in an image forming apparatus and develops a toner image on a photoconductor, and includes a toner carrier that faces the photoconductor, and the toner carrier. A scattering toner preventing member facing the photosensitive member via a predetermined gap on the downstream side of the photosensitive member in the moving direction of the photosensitive member, and the image forming apparatus includes the scattering toner. A suction hole that is located downstream of the prevention member in the moving direction and is provided with a suction hole for sucking toner, and the scattering toner prevention member faces the photoconductor. The opposite surface is provided with a recess that serves as a flow path for guiding the toner to the suction hole, and the toner carrier has a cylindrical shape extending in a predetermined direction. More than the toner bearing than the suction hole. It is provided at a position spaced from said predetermined direction of the end portion of the body, characterized by.
A developing device according to a second aspect of the present invention is a developing device that is used in an image forming apparatus and develops a toner image on a photoconductor, and includes a toner carrier facing the photoconductor, and the toner carrier A scattering toner preventing member facing the photosensitive member via a predetermined gap on the downstream side of the photosensitive member in the moving direction of the photosensitive member, and the image forming apparatus includes the scattering toner. A suction hole that is located downstream of the prevention member in the moving direction and is provided with a suction hole for sucking toner, and the scattering toner prevention member faces the photoconductor. The opposed surface is provided with a recess serving as a flow path for guiding the toner to the suction hole, and the scattered toner preventing member is a main surface that constitutes a part of the opposed surface and has a notch. Has a main surface provided And body, includes a cover member covering the cut-out from the back side of the main surface, the recess, that is formed by said cover member and said body, characterized by.

  The present invention is also directed to an image forming apparatus including the developing device.

  According to the present invention, it is possible to suppress a decrease in image quality.

1 is a diagram illustrating an overall configuration of an image forming apparatus. It is an external perspective view of an image forming unit having a developing device. 3A is an external perspective view of the developing device, and FIGS. 3B and 3C are enlarged views of the developing device. It is the figure which planarly viewed the developing device from the upper side of the perpendicular direction. FIG. 5A is a cross-sectional structural view taken along line AA of the developing device, FIG. 5B is a cross-sectional structural view taken along line BB of the developing device, and FIG. It is a sectional structure figure in CC. It is an enlarged view of a main body and a cover member. 2 is a configuration diagram of a developing device described in Patent Document 1. FIG.

  A developing device and an image forming apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

(Configuration of image forming apparatus)
Hereinafter, an image forming apparatus including a developing device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating an overall configuration of the image forming apparatus 1.

  The image forming apparatus 1 is an electrophotographic color printer and is configured to synthesize images of four colors (Y: yellow, M: magenta, C: cyan, K: black) in a so-called tandem system. is there. The image forming apparatus 1 has a function of forming an image on a sheet based on image data read by a scanner. As shown in FIG. 1, the image forming apparatus 1 has a printing unit 2, a sheet feeding unit 15, a timing roller pair 19, a fixing unit. A device 20 and a paper discharge tray 21 are provided.

  The paper supply unit 15 serves to supply paper one by one and includes a paper tray 16 and a paper supply roller 17. A plurality of sheets in a state before printing are stacked on the sheet tray 16. The paper feed roller 17 takes out the paper placed on the paper tray 16 one by one. The timing roller pair 19 conveys the paper while adjusting the timing so that the toner image is secondarily transferred to the paper in the printing unit 2.

  The printing unit 2 forms a toner image on the paper supplied from the paper supply unit 15, forms an image forming unit (22Y, 22M, 22C, 22K), an optical scanning device 6 (6Y, 6M, 6C, 6K), and a transfer. A portion 8 (8Y, 8M, 8C, 8K), an intermediate transfer belt 11, a driving roller 12, a driven roller 13, a secondary transfer roller 14, and a cleaning device 18 are included. The image forming units (22Y, 22M, 22C, 22K) include a photosensitive drum 4 (4Y, 4M, 4C, 4K), a charger 5 (5Y, 5M, 5C, 5K), and a developing device 7 (7Y, 7M). , 7C, 7K) and cleaner 9 (9Y, 9M, 9C, 9K).

  The photosensitive drum 4 (4Y, 4M, 4C, 4K) has a cylindrical shape, and is rotated clockwise in FIG. The charger 5 (5Y, 5M, 5C, 5K) charges the peripheral surface of the photosensitive drum 4 (4Y, 4M, 4C, 4K). The optical scanning device 6 (6Y, 6M, 6C, 6K) is controlled by a control unit (not shown) so that the beam B (BY, BY) is applied to the peripheral surface of the photosensitive drum 4 (4Y, 4M, 4C, 4K). BM, BC, BK) are scanned. Thereby, an electrostatic latent image is formed on the peripheral surface of the photosensitive drum 4 (4Y, 4M, 4C, 4K).

  The developing device 7 (7Y, 7M, 7C, 7K) develops a toner image based on the electrostatic latent image on the photosensitive drum 4 (4Y, 4M, 4C, 4K). Details of the developing device 7 will be described later.

  The intermediate transfer belt 11 is stretched between the driving roller 12 and the driven roller 13. The toner image developed on the photosensitive drum 4 is primarily transferred to the intermediate transfer belt 11. The transfer unit 8 is disposed so as to face the inner peripheral surface of the intermediate transfer belt 11 and plays a role of primary transfer of the toner image formed on the photosensitive drum 4 to the intermediate transfer belt 11. The cleaner 9 collects the toner remaining on the peripheral surface of the photosensitive drum 4 after the primary transfer. The driving roller 12 is rotated by an intermediate transfer belt driving unit (not shown in FIG. 1), thereby driving the intermediate transfer belt 11 in the direction of arrow α. As a result, the intermediate transfer belt 11 conveys the toner image to the secondary transfer roller 14.

  The secondary transfer roller 14 faces the intermediate transfer belt 11 and has a drum shape. The secondary transfer roller 14 secondarily transfers the toner image carried by the intermediate transfer belt 11 to a sheet passing between the secondary transfer roller 14 and the intermediate transfer belt 11 by applying a transfer voltage. The cleaning device 18 removes the toner remaining on the intermediate transfer belt 11 after the secondary transfer of the toner image onto the paper.

  The sheet on which the toner image is secondarily transferred is conveyed to the fixing device 20. The fixing device 20 fixes the toner image on the paper by performing heat treatment and pressure treatment on the paper. Printed paper is placed on the paper discharge tray 21.

(Configuration of developing device)
Next, details of the configuration of the developing device 7 will be described with reference to the drawings. Hereinafter, the developing device 7K will be described as an example. FIG. 2 is an external perspective view of the image forming unit 22K having the developing device 7K. FIG. 3A is an external perspective view of the developing device 7K, and FIGS. 3B and 3C are enlarged views of the developing device 7K. FIG. 4 is a plan view of the developing device 7K as viewed from above in the vertical direction. FIG. 5A is a cross-sectional structural view taken along line AA of the developing device 7K, FIG. 5B is a cross-sectional structural view taken along line BB of the developing device 7K, and FIG. FIG. 7 is a cross-sectional structure view taken along the line CC of the device 7K. Hereinafter, the longitudinal direction of the developing device 7K is defined as the x-axis direction. Further, the vertical direction in the developing device 7K is defined as the z-axis direction, and the direction orthogonal to the x-axis direction and the z-axis direction is defined as the y-axis direction.

  As shown in FIG. 2, the developing device 7K constitutes a part of the image forming unit 22K. 3 to 5, the developing device 7K includes a developing roller (toner carrier) 72K, a supply roller 74K, a stirring roller 76K, a housing portion 78K, a scattering toner preventing member 80K, a suction duct 82K, and a seal member. 90-1K and 90-2K.

  The accommodating portion 78K constitutes the main body of the developing device 7K, accommodates toner, and stores the developing roller 72K, the supply roller 74K, and the stirring roller 76K. The agitation roller 76K agitates the toner in the storage portion 78K and negatively charges it. The supply roller 74K supplies negatively charged toner to the developing roller 72K.

  As shown in FIGS. 1 and 5, the developing roller 72K faces the photosensitive drum 4K with a predetermined gap, and extends in the x-axis direction as shown in FIGS. It has a cylindrical shape. The developing roller 72K is rotated about the axis Ax shown in FIGS. 3 and 4 in the same direction as the photosensitive drum 4K (that is, clockwise in FIG. 1). The developing roller 72K having the above-described configuration carries toner on its peripheral surface, and is exposed in a rectangular shape from the storage portion 78K as shown in FIGS. The developing roller 72K faces the photosensitive drum 4K at a portion exposed from the housing portion 78K, and applies toner to the photosensitive drum 4K.

  Here, as shown in FIG. 3, the developing roller 72K has a carrying area A1 and non-carrying areas A2 and A3. The non-carrying regions A2 and A3 are provided at the end portions on the negative side and the positive side in the x-axis direction of the developing roller 72, and are regions that do not carry toner. The non-carrying regions A2 and A3 are configured by attaching metal covers to both ends of the developing roller 72K. The carrying area A1 is provided between the non-carrying areas A2 and A3 and carries toner.

  The scattered toner preventing member 80K is a member for preventing the toner from scattering from the gap between the photosensitive drum 4K and the developing roller 72K. Therefore, as shown in FIG. 5, the scattering toner preventing member 80K is downstream in the moving direction of the peripheral surface of the photosensitive drum 4K from the developing roller 72K (that is, upstream in the moving direction of the peripheral surface of the developing roller 72K). 2 has a facing surface S1 that faces the photosensitive drum 4K with a predetermined gap. As shown in FIGS. 3 and 5, the scattering toner preventing member 80K includes a main body 84K and cover members 86-1K and 86-2K.

  As shown in FIG. 3, the main body 84K is a plate-like member having substantially the same length as the developing roller 72K in the x-axis direction, and is a main surface S2 that constitutes a part of the opposing surface S1, and is a photoreceptor. The main surface S2 is opposed to the drum 4K. As shown in FIG. 5, the main surface S2 covers the gap between the photosensitive drum 4K and the developing roller 72K. Thus, the toner is prevented from scattering out of the developing device 7K due to the airflow generated by the rotation of the photosensitive drum 4K. Further, as shown in FIG. 3, rectangular cutouts c1 and c2 are provided on the main surface S2. The notches c1 and c2 are formed by cutting a part of the long side on the positive direction side in the z-axis direction in the vicinity of both ends in the x-axis direction of the main body 84K.

  As shown in FIG. 3, the cover members 86-1K and 86-2K are plate-like members that cover the notches c1 and c2 from the back surface side of the main surface S2 of the main body 84K. The main surface S3 of the cover members 86-1K and 86-2K faces the photosensitive drum 4K as shown in FIG. Therefore, the opposing surface S1 is composed of main surfaces S2 and S3. The cover members 86-1K and 86-2K are detachably attached to the main body 84K with a double-sided tape or an adhesive.

  Here, as described above, the cover members 86-1 </ b> K and 86-2 </ b> K are plate-like members attached to the back surface side of the main body 84 </ b> K. Therefore, there is a step between the main surface S2 of the main body 84K and the main surface S2 of the cover members 86-1K and 86-2K, as shown in FIG. Thus, the opposing surface S1 of the scattering toner preventing member 80K is provided with recesses g1 and g2 constituted by the main body 84K and the cover members 86-1K and 86-2K. The recesses g1 and g2 are recessed in a direction away from the photosensitive drum 4K. That is, the size of the gap between the photosensitive drum 4K and the scattered toner preventing member 80K in the recesses g1 and g2 is such that the gap between the photosensitive drum 4K and the scattered toner preventing member 80K in the portion other than the recessed portions g1 and g2 of the facing surface S1. It is larger than the size of.

  A gap is provided between the main body 84K and the cover members 86-1K and 86-2K. FIG. 6 is an enlarged view of the main body 84K and the cover members 86-1K and 86-2K.

  The cover members 86-1K and 86-2K are plate-like members attached to the back surface of the facing surface S1 of the main body 84K. At this time, the cover members 86-1K and 86-2K are affixed to the main body 84K so that gaps g10 and g11 are formed between the main body 84K and the cover members 86-1K and 86K-2. In FIG. 6, gaps g10 and g11 are formed between the negative ends of the cover members 86-1K and 86-2K in the z-axis direction and the main body 84K. The widths of the gaps g10 and g11 are, for example, 0.2 mm to 0.5 mm.

  As shown in FIGS. 3 and 5, the suction duct 82 </ b> K is provided on the positive side in the z-axis direction of the housing portion 78 </ b> K, and the inside is made negative by the negative pressure generation source provided in the image forming apparatus 1. It is a box-shaped member that is kept. Suction holes h1 and h2 are provided in the suction duct 82K. The suction holes h1 and h2 are located downstream of the scattered toner preventing member 80K in the moving direction of the peripheral surface of the photosensitive drum 4K, and leaked from the gap between the photosensitive drum 4K and the scattered toner preventing member 80K. It is provided to suck toner.

  Here, as shown in FIG. 3, the suction holes h1 and h2 are provided in the vicinity of both ends in the x-axis direction of the developing roller 72K. More specifically, the suction holes h1 and h2 are provided so as to overlap the non-carrying regions A2 and A3, respectively, when viewed in plan from the y-axis direction. The suction hole h1 is provided on the negative side in the x-axis direction with respect to the recess g1, and the suction hole h2 is provided on the positive direction side in the x-axis direction with respect to the recess g2. Accordingly, as shown in FIG. 3, the recesses g1 and g2 are provided at positions farther from both ends in the x-axis direction of the developing roller 72K than the suction holes h1 and h2, respectively.

  As shown in FIG. 3, the seal member 90-1K is in contact with the negative end of the developing roller 72K in the x-axis direction and covers a part of the scattering toner preventing member 80K. Further, as shown in FIG. 3, the seal member 90-2K is in contact with the positive end of the developing roller 72K in the x-axis direction and covers a part of the scattering toner preventing member 80K. Accordingly, the seal members 90-1K and 90-2K prevent a gap from being generated between the developing roller 72K and the scattered toner preventing member 80.

(effect)
According to the developing device 7K configured as described above, it is possible to suppress a decrease in image quality. More specifically, the scattering toner preventing member 80K is provided with recesses g1 and g2 as shown in FIG. The recesses g1 and g2 are located upstream of the suction holes h1 and h2 in the moving direction of the peripheral surface of the photosensitive drum 4K. Therefore, the air flow generated by the rotation of the photosensitive drum 4K passes through the main body 84K of the scattering toner preventing member 80K as shown by the arrows in FIG. 3 than the portions other than the recesses g1 and g2 of the main surface S1. The recesses g1 and g2 are preferentially passed. The airflow passes through the recesses g1 and g2 and then flows into the suction holes h1 and h2. That is, the recesses g1 and g2 function as flow paths for guiding the toner to the suction holes h1 and h2. As a result, the toner is suppressed from being deposited on the scattering toner preventing member 80K, and the image quality is prevented from being deteriorated in the developing device 7.

  Furthermore, according to the developing device 7K, it is possible to suppress a decrease in image quality for the following reason. More specifically, since toner is not carried in the non-carrying areas A2 and A3, the toner is more likely to be scattered in the non-carrying areas A2 and A3 than in the carrying area A1. Therefore, the developing device 7 is provided so that the suction holes h1 and h2 and the non-carrying regions A2 and A3 are overlapped when viewed in plan from the y-axis direction. Thereby, the toner scattered in the non-carrying regions A2 and A3 is easily sucked through the suction holes h1 and h2. As a result, the toner is suppressed from being deposited on the scattering toner preventing member 80K, and the image quality is prevented from being deteriorated in the developing device 7.

  Furthermore, according to the developing device 7K, it is possible to suppress a decrease in image quality for the following reason. More specifically, since toner is not carried in the non-carrying areas A2 and A3, more toner is scattered in the non-carrying areas A2 and A3 than in the carrying area A1. Part of the scattered toner is not sucked by the suction holes h1 and h2, but spreads over the entire facing surface S1 of the scattering toner preventing member 80K, and the toner accumulates on the entire facing surface S1 of the scattering toner preventing member 80K. There is a fear. Therefore, in the developing device 7K, the recesses g1 and g2 are provided at positions farther from the end in the x-axis direction of the developing roller 72K than the suction holes h1 and h2. Accordingly, the flow path for guiding the toner to the suction holes h1 and h2 is formed closer to the center in the x-axis direction on the facing surface S1 of the scattering toner preventing member 80K than the suction holes h1 and h2. As a result, the toner scattered in the non-carrying regions A2 and A3 is guided to the suction holes h1 and h2 by the recesses g1 and g2 before passing through the suction holes h1 and h2 and spreading over the entire facing surface S1. That is, the scattered toner does not easily reach the vicinity of the center in the x-axis direction on the facing surface S1 of the scattered toner preventing member 80K. As a result, the toner is suppressed from being deposited on the scattering toner preventing member 80K, and the image quality is prevented from being deteriorated in the developing device 7.

  Further, according to the developing device 7K, it is possible to suppress a decrease in image quality for the following reason. More specifically, as shown in FIG. 6, gaps g10 and g11 are provided between the cover members 86-1K and 86-2K and the main body 84K. Therefore, as shown in FIG. 6, from the surface of the cover members 86-1K and 86-2K not facing the photoconductor drum 4K (the back surface of the main surface S3) to the main surface S3 facing the photoconductor drum 4K. An air flow is generated toward it. As a result, the recesses g1 and g2 function more effectively as flow paths that guide the scattered toner to the suction holes h1 and h2. As a result, the toner is suppressed from being deposited on the scattering toner preventing member 80K, and the image quality is prevented from being deteriorated in the developing device 7.

  The developing device 7K is provided with a suction duct 82K. However, the developing device 7K need not include the suction duct 82K. In this case, the image forming apparatus 1 only needs to have the suction duct 82K.

  Further, in the developing device 7K, the recesses g1 and g2 are constituted by a main body 84K and cover members 86-1K and 86-2K. However, the configuration of the recesses g1 and g2 is not limited to this. The recesses g1 and g2 may be configured by processing so that the main surface S2 of the main body 84K is recessed without using the cover members 86-1K and 86-2K.

  In the above description, the developing device 7K has been described as an example. However, the developing devices 7Y, 7M, and 7C can be said to be the same as the developing device 7K.

  The present invention is useful for a developing device and an image forming apparatus, and is particularly excellent in that deterioration in image quality can be suppressed.

A1 carrying area A2, A3 non-carrying area S1 facing surface c1, c2 notch g1, g2 recess g10, g11 gap h1, h2 suction holes 4Y, 4M, 4C, 4K photosensitive drum 7Y, 7M, 7C, 7K developing device 72K Developing roller 74K Supply roller 76K Stirring roller 78K Housing portion 80K Scatter toner prevention member 82K Suction duct 84K Main body 86K-1, 86-2K Cover member

Claims (6)

A developing device used in an image forming apparatus for developing a toner image on a photoreceptor,
A toner carrier facing the photoconductor;
A scattering toner preventing member facing the photoconductor through a predetermined gap on the downstream side in the moving direction of the photoconductor from the toner carrier;
With
The image forming apparatus includes a suction duct which is a suction hole located on the downstream side in the moving direction with respect to the scattering toner prevention member and is provided with a suction hole for sucking toner;
The scattered on the facing surfaces of the toner preventing member is opposed to the photosensitive member, a concave portion serving as a flow path for guiding toner to the suction hole is provided,
The toner carrier has a cylindrical shape extending in a predetermined direction,
The concave portion is provided at a position farther from the end in the predetermined direction of the toner carrier than the suction hole;
A developing device. A developing device used in an image forming apparatus for developing a toner image on a photoreceptor,
A toner carrier facing the photoconductor;
A scattering toner preventing member facing the photoconductor through a predetermined gap on the downstream side in the moving direction of the photoconductor from the toner carrier;
With
The image forming apparatus includes a suction duct which is a suction hole located on the downstream side in the moving direction with respect to the scattering toner prevention member and is provided with a suction hole for sucking toner;
The scattered on the facing surfaces of the toner preventing member is opposed to the photosensitive member, a concave portion serving as a flow path for guiding toner to the suction hole is provided,
The scattering toner preventing member is
A main surface constituting a part of the facing surface, a main body having a main surface provided with a notch;
A cover member covering the notch from the back side of the main surface;
Contains
The recess is constituted by the main body and the cover member;
A developing device. The developing device includes:
The suction duct,
More
An apparatus according to claim 1 or claim 2, characterized in. The toner carrier has non-carrying regions that do not carry toner at both ends in the predetermined direction,
The suction hole is provided so as to overlap each of the non-carrying regions when seen in a plan view from a direction orthogonal to the predetermined direction;
The developing device according to claim 1 . A gap is provided between the cover member and the main body,
The developing device according to claim 2 . A developing device according to any one of claims 1 to 5 is provided.
An image forming apparatus.

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