JP2007256657A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus having a developing unit cooling mechanism capable of cooling a developing sleeve 11 and a bearing part constituting a developing unit 1 in the image forming apparatus without disturbing or scattering a toner layer carried on the developing sleeve 11, thereby preventing the deformation of a resin member caused by heat or the occurrence of failure that the characteristic of toner is changed to form a black dot in advance. <P>SOLUTION: The image forming apparatus includes: the developing unit 1 having the developing sleeve 11 and a layer thickness regulating blade 12 regulating toner layer thickness on the developing sleeve 11; and a drum shutter with which the exposed surface of a photoreceptor drum 2 is covered when the developing unit 1 is not attached and which makes the exposed surface thereof open when the developing unit 1 is attached. By extending the layer thickness regulating blade 12 along the outer wall of the housing 10 of the developing unit 1, a duct 13 for cooling the developing unit 1 by introducing in-machine cooling air is formed by an extension part 121 and the drum shutter 23 when the developing unit 1 is attached to the image forming apparatus. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine using an electrophotographic system, and more particularly, a developing sleeve (developing roller) installed facing a photoreceptor and a bearing thereof. The present invention relates to an image forming apparatus capable of preventing overheating.

  In image forming apparatuses such as copiers, printers, facsimiles, and composite machines using electrophotography, there are many heat generation points such as a fixing device, a developing sleeve (developing roller), and a bearing portion thereof. However, the resin member is deformed by heat, or a change in properties of the toner occurs, causing various problems.

  In particular, in the developing sleeve installed facing the photoconductor (image carrier), the toner staying on the developing roller is compressed by the layer thickness regulating blade that regulates the toner layer thickness, and the developing sleeve rotates. Heat generation due to friction changes the properties of the toner and causes black spots to occur due to sticking. Also, since the bearing portion of the developing sleeve becomes hot as it rotates, it is one of the most desired locations for cooling.

  For such heat generation, a cooling fan that discharges the heat generated in the machine to the outside of the machine is provided to release the heat generated in the heat generating part to the outside. Since the toner is carried, if the wind is sent as it is, the carried toner is disturbed or scattered, and the formed image is affected.

  This also applies to an image carrier that carries a toner image formed by an electrophotographic method. For this reason, for example, in Patent Document 1, the image carrier 1 is configured as one unit together with its peripheral components, and is In an image forming apparatus that is detachably mounted, a duct that guides air to a heat radiating means in order to minimize the influence of heat on the unit without enlarging the unit comprising the image carrier and its peripheral components An exhaust flow path is formed by a shutter and a duct that covers and protects the image carrier when the unit is removed, and the air flows toward the image carrier by regulating the flow of air toward the duct. An image forming apparatus that can cool the unit while preventing this is shown.

  Japanese Patent Application Laid-Open No. 2004-26883 discloses an image carrier when a detachable process unit is removed from the main body in order to satisfactorily exhaust high-temperature air from the image forming apparatus and prevent a temperature rise in the image forming apparatus. When the shutter is rotated to the open position when the process unit is mounted, a ventilation duct is formed between the shutter and the outer peripheral surface of the case of the process unit, and a high temperature at a position away from the fan is provided. An image forming apparatus is shown in which air can be exhausted out of the image forming apparatus through the ventilation duct.

  Further, in Patent Document 3, in order to efficiently cool the inside of the cartridge by utilizing the airflow that flows around the cartridge of the LBP main body, the rectification that protrudes to the outside of the cartridge in conjunction with the opening / closing of the shutter for protecting the photosensitive drum is provided on the top of the cartridge. There is shown an image forming apparatus in which a plate is provided and air flow is taken into a cartridge by restricting air flow from a fan installed in the LBP main body.

JP 11-249368 A Japanese Unexamined Patent Publication No. 2000-1332060 JP 2004-101672 A

  However, the image forming apparatuses disclosed in Patent Documents 1 to 3 are intended to discharge heat generated mainly from the fixing device to the outside of the apparatus or to send air into the process cartridge. In the developing sleeve on which toner is carried, when the wind hits the carried toner, the carried toner is disturbed or scattered to affect an image formed, but cooling of such a portion is not considered.

  Therefore, in the present invention, the developing sleeve and the bearing portion can be cooled without disturbing or scattering the toner layer carried on the developing sleeve, the resin member is deformed by heat, An object of the present invention is to provide an image forming apparatus including a developing unit cooling mechanism that can prevent problems such as black spots due to changes in properties.

In order to solve the above problems, an image forming apparatus according to the present invention provides:
A developing unit that includes a developing sleeve and a layer thickness regulating blade that regulates the toner layer thickness on the developing sleeve, and that is mounted / removed on the image forming apparatus main body, and that is photosensitive in conjunction with the mounting / removing operation of the developing unit. In an image forming apparatus including a drum shutter that closes and opens an exposed surface of a body drum,
The extension portion of the layer thickness regulating blade that extends in a direction away from the developing sleeve along the outer wall of the housing of the developing unit, and the drum shutter at a position where the exposed surface of the photosensitive drum is opened. A duct extending in the axial direction of the developing sleeve is formed, and an in-machine cooling air is introduced into the duct to cool the developing unit.

  As described above, the image forming apparatus configured so that the developing unit can be attached to and detached from the main body is provided with a drum shutter that closes the exposed surface of the photosensitive drum when the developing unit is not installed, and a layer thickness regulating blade, and is cooled. By forming a duct that introduces air, the toner stays on the layer thickness regulating blade without adding new parts and without disturbing or scattering the toner layer carried on the developing sleeve. It is possible to cool the heat generated by the friction between the developing sleeve and the bearing portion thereof. In addition, since the cooling is performed using a layer thickness regulating blade that is closest to the developing sleeve that needs the most cooling, the above cooling can be performed efficiently, and the resin member is deformed by heat or the properties of the toner are changed. It is possible to provide an image forming apparatus having a developing unit cooling mechanism that can prevent problems such as black spots due to fixation and prevent formation of a good image over a long period of time.

  The developing sleeve and its bearing portion can be reliably cooled by introducing cooling air into the duct by an outside air suction fan or an in-machine air exhaust fan provided at a position facing the extending direction of the duct. .

  In addition, a buffer member is disposed on the drum shutter side or the layer thickness regulating blade side in the duct space portion, and the gap between the contact portion of the drum shutter and the layer thickness regulating blade can be closed by the buffer member. As a result, it is possible to provide an image forming apparatus having a cooling mechanism that can cool the developing sleeve and its bearing portion reliably without cooling air leaking out of the duct.

  Furthermore, the drum shutter is provided in a photosensitive drum side unit or a process unit having a photosensitive drum and a member for forming a latent image on the photosensitive drum, and from the start timing of loading / unloading operation of the developing unit. A mechanism for delaying and rotating between the closed position and the open position of the exposed surface of the photosensitive drum is provided between the developing unit and the photosensitive drum side unit, or the process unit. Even when the loading / unloading operation is performed, it is possible to reliably close the exposed surface of the photosensitive drum and form the duct without causing the drum shutter and the developing unit to collide with each other.

  According to the present invention, it is possible to actively cool a developing sleeve, a bearing portion, and the like that have been difficult to cool in the related art. It is possible to prevent various adverse effects such as black spots and problems. Moreover, since it can be carried out using a conventionally provided drum shutter, an image forming apparatus that is advantageous in terms of cost can be obtained.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  FIG. 1 is a schematic cross-sectional view of a cooling mechanism section of a developing unit 1 in an image forming apparatus according to the present invention. The developing unit 1 is mounted on an image forming apparatus main body, and a layer thickness regulating blade extension 121 and a drum shutter 23 FIG. 2 is a sectional view showing a state in which the duct 13 is formed. FIG. 2 is a sectional view showing a state in which the developing unit 1 starts to be removed from the main body of the image forming apparatus. The drum shutter 23 still opens the exposed surface of the photosensitive drum 2. FIG. 3 is a sectional view showing a state in which the developing unit 1 is removed from the image forming apparatus main body and the drum shutter 23 is located at a position where the exposed surface of the photosensitive drum 2 is opened. FIG. 3 is a perspective view of a state in which the developing unit 1 is mounted on the main body of the image forming apparatus, and a layer thickness regulating blade extension 121 and a drum shutter 23 form a duct 13.

  FIG. 1 is a schematic cross-sectional view of an image forming apparatus according to the present invention. The image forming apparatus according to the present invention develops a latent image formed on a photosensitive drum 2 and a developing sleeve 11 on the developing sleeve 11. The developing unit 1 having a layer thickness regulating blade 12 that regulates the toner layer thickness is configured so as to be attached to and detached from the image forming apparatus main body. Then, when the developing unit 1 is removed in order to take out the paper remaining inside due to a paper jam or the like, the exposed surface of the photosensitive drum 1 is closed so as not to be damaged by touching the photosensitive drum 1 by mistake. A drum shutter 23 is provided. When the developing unit 1 is mounted on the main body of the image forming apparatus, the drum shutter 23 is positioned at a position where the exposed surface of the photosensitive drum 1 is opened, and is extended away from the developing sleeve 11 of the layer thickness regulating blade 12. The extended portion 121 and the drum shutter 23 constitute a duct 13, and an in-machine cooling air is introduced into the duct 13 so that the developing sleeve 11 and its bearing of the developing unit 1 can be cooled. It is.

  That is, the image forming apparatus forms a toner image by developing the latent image and the photosensitive drum 2 that forms a latent image by exposure to light uniformly charged by the charging device 21 and modulated by image data. Therefore, a developing sleeve 11 that carries a toner thin layer and faces the photosensitive drum 2, a cleaning device 22 that cleans residual toner on the photosensitive drum 2, and the like are provided. Therefore, in the image forming apparatus of the present invention, the developing sleeve 11 and the layer thickness regulating blade 12 for regulating the layer thickness of the toner carried by the developing sleeve 11 to be a thin layer are accommodated in the developing unit 1. The image forming apparatus main body is configured to be attachable / detachable, and the layer thickness regulating blade 12 is extended along the outer wall of the developing unit housing 10 so as to be separated from the developing sleeve 11, and the extending part 121 and the photoconductor. The duct 13 is constituted by the drum shutter 23 rotated to a position where the exposed surface of the drum 2 is opened.

  By providing the duct 13 for cooling the developing sleeve 11 in the developing unit 1 in this way, the toner layer carried on the developing sleeve 11 is further disturbed or scattered without adding new parts. Accordingly, the heat generated by the friction with the toner staying on the layer thickness regulating blade 12 and transmitted to the developing sleeve 11 and its bearing can be indirectly cooled. In addition, since the cooling is performed using the layer thickness regulating blade 12 that is closest to the developing sleeve 11 that needs the most cooling, the cooling can be performed efficiently, and the resin member is deformed by heat and the properties of the toner are changed. Thus, it is possible to provide an image forming apparatus having a developing unit cooling mechanism that can prevent the occurrence of problems such as black spots due to fixation, and can form a good image over a long period of time.

  The above is the outline of the present invention. The present invention will be described in more detail. First, when the developing unit 1 is mounted on the image forming apparatus main body, the developing sleeve 11 faces the photosensitive drum 2 as described above. A layer thickness regulating blade 12 that is provided and regulates the toner layer thickness on the developing sleeve 11 is disposed. The layer thickness regulating blade 12 is provided with an extending portion 121 that extends along the outer wall of the housing 10 of the developing unit 1 in a direction away from the developing sleeve 11.

  On the other hand, the drum shutter 23 provided on the process unit 20 side including at least a member for forming a latent image on the photosensitive drum 2 such as the main body of the image forming apparatus or the photosensitive drum 2 or the charging device has this layer. When the duct 13 is configured in cooperation with the extending portion 121 of the thickness regulating blade 12, the gap formed between the drum shutter 23 and the layer thickness regulating blade extending portion 121 side is closed. The configured gap filling members 231 and 232 are provided. Of course, the gap filling members 231 and 232 may be provided not on the drum shutter 23 side but on the layer thickness regulating blade extending portion 121 side.

  As shown in FIG. 1, when the developing unit 1 is inserted into the main body of the image forming apparatus, the drum shutter 23 rotates from the closed position of the open surface of the photosensitive drum 2 and is positioned at the open position shown in FIG. 1 is completely attached to the main body of the image forming apparatus, the layer thickness regulating blade extending portion 121 comes into contact with the gap filling members 231 and 232 provided in the layer thickness regulating blade extending portion 121, and the duct 13 is formed. That is why.

  Then, the rotation of the drum shutter 23 from the closed position of the open surface of the photosensitive drum 2 to the open position shown in the drawing is performed when the shutter arm 24 provided on the image forming apparatus main body side is attached and detached with the developing unit 1. This is transmitted to the gear 27 to which the drum shutter 23 is attached via the gears 25 and 26.

  FIG. 2 is a cross-sectional view showing a state immediately before the drum shutter 23 is rotated from the open position to the closed position of the exposed surface of the photosensitive drum 2 in an attempt to take out the developing unit 1 from the main body of the image forming apparatus. FIG. 3 is a cross-sectional view showing a state where the developing unit 1 is completely removed from the image forming apparatus main body and the drum shutter 23 is rotated to the closed position of the exposed surface of the photosensitive drum 2.

  First, in FIG. 2, for example, in order to take out the paper remaining in the image forming apparatus main body due to paper jam, the developing unit 1 is going to be taken out and is moved rightward in the drawing. In this state, the layer thickness regulating blade extension 121 of the developing unit 1 is separated from the drum shutter 23, but has not reached the position where the developing unit 1 rotates the shutter arm 24. It is located at the same position as FIG.

  When the developing unit 1 is further pulled out, an end portion of the developing unit 1 (not shown) comes into contact with the shutter arm 24 and is rotated counterclockwise in the drawing as the developing unit 1 is pulled out. Therefore, the gear provided on the shutter arm 24 rotates the gear 25, and further rotates the gear 26 to rotate the gear 27 to which the drum shutter 23 is attached. Therefore, the drum shutter 23 starts to rotate in the closed position direction of the exposed surface of the photosensitive drum 2.

  When the developing unit 1 is further pulled out, the drum shutter 23 reaches the closed position of the exposed surface of the photosensitive drum 2 as shown in FIG. 3, and the user takes out the paper remaining in the apparatus by jam or the like. Even if it is put in the machine, it cannot be touched on the photosensitive drum 2.

  In this way, the drum shutter 23 rotates between the closed position and the open position of the exposed surface of the photosensitive drum 2, and the drum shutter 23 is exposed to the exposed surface of the photosensitive drum 2 as shown in FIG. FIG. 4 is a partial perspective view of the duct 13 in a state where the duct 13 is configured in cooperation with the layer thickness regulating blade extension 121.

  In FIG. 4, reference numeral 30 denotes a frame of the image forming apparatus. The frame 30 is provided with a fan 31 for blowing outside air into the image forming apparatus main body, and the outside air is indicated by arrows 32 and 33. It flows through the air passage formed at the location. Reference numeral 1 denotes a developing unit as described above, and a layer thickness regulating blade extending portion 121 is provided on the photosensitive drum unit 20 side, and a duct 13 is constituted by the drum shutter 23 in contact with the photosensitive drum unit 20 side. Yes. Then, the outside air introduced by the fan 31 flows through the duct 13 as indicated by an arrow 33, and the layer thickness regulating blade 12, the indirect but developing sleeve 11, and the developing sleeve bearings are conventionally developed. The portion that could not be cooled because the toner layer carried on the sleeve 11 is disturbed or scattered is cooled.

  Therefore, as described above, it is possible to reduce the adverse effect on the image due to the heat generated inside the machine, and this cooling is performed by the drum shutter 23 and the layer thickness regulating blade conventionally provided in the image forming apparatus main body. 12 or the like is used, so that an image forming apparatus having a developing unit cooling mechanism which is advantageous in terms of cost can be obtained.

  Although the fan 31 has been described as introducing outside air into the image forming apparatus main body, it is obvious that the fan 31 may discharge warmed air inside the image forming apparatus main body to the outside.

  According to the present invention, the developing sleeve 11, and further the bearing of the developing sleeve, etc., which could not be cooled because the toner layer carried on the developing sleeve 11 was disturbed or scattered by a very simple configuration. It is possible to provide an image forming apparatus having a developing unit cooling mechanism that can be cooled indirectly but can form a good image over a long period of time.

FIG. 2 is a schematic cross-sectional view of a cooling mechanism portion of the developing unit 1 in the image forming apparatus according to the present invention. Shows the state. FIG. 6 is a cross-sectional view showing a state in which the developing unit 1 has started to be removed from the image forming apparatus main body, and shows a state where the drum shutter 23 is still in a position where the exposed surface of the photosensitive drum 2 is opened. FIG. 3 is a cross-sectional view showing a state where the developing unit 1 is removed from the image forming apparatus main body and the drum shutter 23 is located at a position where the exposed surface of the photosensitive drum 2 is opened. FIG. 3 is a perspective view of a state in which the developing unit 1 is mounted on the main body of the image forming apparatus, and a layer thickness regulating blade extension 121 and a drum shutter 23 form a duct 13.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing unit 10 Developing unit housing 11 Developing sleeve 12 Layer thickness regulating blade 121 Layer thickness regulating blade extension 13 Duct 2 Photosensitive drum 20 Photosensitive drum unit 21 Charging device 22 Cleaning device 23 Drum shutter 231, 232 Gap filling member 24 Shutter Arm 25, 26, 27 Gear

Claims (4)

A developing unit that includes a developing sleeve and a layer thickness regulating blade that regulates the toner layer thickness on the developing sleeve, and that is mounted / removed on the image forming apparatus main body, and that is photosensitive in conjunction with the mounting / removing operation of the developing unit. In an image forming apparatus including a drum shutter that closes and opens an exposed surface of a body drum,
The extension portion of the layer thickness regulating blade that extends in a direction away from the developing sleeve along the outer wall of the housing of the developing unit, and the drum shutter at a position where the exposed surface of the photosensitive drum is opened. An image forming apparatus comprising: a duct extending in an axial direction of a developing sleeve; and cooling the developing unit by introducing an in-machine cooling air into the duct.   2. The image forming apparatus according to claim 1, wherein cooling air is introduced into the duct by an outside air suction fan or an in-machine air exhaust fan provided at a position facing the extending direction of the duct.   A buffer member is disposed on the drum shutter side or the layer thickness regulating blade side in the duct space, and the gap between the contact portion of the drum shutter and the layer thickness regulating blade can be closed by the buffer member. The image forming apparatus described in 1 or 2.   The drum shutter is provided in a photosensitive drum side unit or a process unit having a photosensitive drum and a member for forming a latent image on the photosensitive drum, and is delayed from the loading / demounting operation start timing of the developing unit. 2. A mechanism for rotating between the closed position and the open position of the exposed surface of the photosensitive drum is provided between the developing unit and the photosensitive drum side unit or the process unit. 4. The image forming apparatus according to any one of items 1 to 3.

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