JP2013257513A - Developing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase an effective area of a pressure relief filter with a simple configuration to extend the life of the pressure relief filter, and improve a maintenance management property of the pressure relief filter.SOLUTION: A developing device 20 stirs a developer stored in a developer tank to cause frictional charge on the developer, and supplies the charged developer to an electrostatic latent image on a latent image carrier. An opening of the developer tank provided to a body part 21 of the developing device 20 communicates with a pressure relief filter unit 23 provided separately from the body part 21 through a ventilation path 22; and the pressure relief filter unit 23 is provided with a pressure relief filter 24 that suppresses pressure rise in the developer tank.

Description

The present invention relates to a developing device and an image forming apparatus. More specifically, the present invention relates to a developing device mounted on an electrophotographic image forming apparatus such as a copying machine, a facsimile, or a printer.
About.

  Conventionally, various image forming apparatuses using an electrophotographic system have been devised as image forming apparatuses such as copying machines, facsimiles, and printers, and are well known in the art. In the image forming process, an electrostatic latent image is formed on the surface of a photosensitive drum as a latent image carrier, and the electrostatic latent image on the photosensitive drum is developed with toner as a developer supplied from a developing device. The visualized and developed image is transferred onto a recording paper (also referred to as paper, recording medium, or recording material) by a transfer device to carry the image, and a toner image on the recording paper is transferred by a fixing device using pressure, heat, or the like. It is established by the process of establishment.

  As a developer used in a developing device provided in an electrophotographic image forming apparatus, a two-component developer in which a toner and a carrier are mixed, or a one-component developer not containing a carrier is widely used.

  In any developer, the toner needs to be charged. Therefore, in the case of a two-component developer, a process in which the toner and the carrier are stirred and mixed to frictionally charge the toner is used. In the case of a one-component developer, a doctor blade that regulates the layer thickness is used. A triboelectric charging process when passing is used.

  Further, the developing device has a developing tank that is substantially sealed except for a portion facing the latent image carrier. Inside the developing tank, for example, a developing roller that supplies toner to the photosensitive member, a developing roller, A rotating member such as a developer agitation paddle for agitating the toner supplied to the roller is provided, and the developer is agitated and mixed in the developing tank.

  When the rotating member inside the developing tank rotates, the air pressure inside the developing tank rises, and the toner blows out from the gap between the latent image carrier and the developing tank part facing the latent image carrier, and the toner is developed into the developing tank. It becomes easy to scatter outside.

  In order to prevent the toner scattering due to the pressure increase in the developing tank, an exhaust port (opening) for discharging the air current in the developing tank caused by the rotation of the developing roller or the like is provided in the upper part of the developing tank. In addition, a pressure relief filter (toner outflow prevention filter) is installed to prevent the air from being discharged from the exhaust port to increase the air pressure in the developing tank and to prevent the toner from scattering from the exhaust port. Are known.

  However, in the developing device having such a configuration, the pressure releasing filter becomes clogged with toner while the developing device is operated, and when the clogged state becomes severe, the pressure releasing effect in the developing tank is sufficiently exhibited. And the toner is scattered.

  Here, if the toner scattering cannot be sufficiently prevented, the inside of the image forming apparatus is contaminated with the developer, which may cause the backside of the recording paper passed by the toner adhering to the contaminated image forming apparatus. Problems arise. Further, if the blown-out toner adheres to an uncharged area of the latent image carrier, it may cause a dirty image to be formed.

  In order to prevent these problems, it is necessary to periodically replace the pressure relief filter.

  In this regard, for example, Patent Document 1 provides a masking member that can move along the surface of the depressurization filter, and restricts the effective area (effective area) of the depressurization filter so that it can be used in a divided manner. A developing device that realizes a long service life by extending the clogging time is disclosed.

  FIG. 7 shows an external configuration diagram of the developing device described in Patent Document 1 (FIG. 3 of Patent Document 1). In the developing device 90 shown in FIG. 7, a part of the pressure release filter 91 is covered with a masking member 92, and only part of the pressure release filter 91 is used at the start of use, and the pressure release filter 91 is clogged. At the previous timing, the masking member 92 is slid to expose the unused surface of the pressure release filter 91, thereby maintaining the pressure release function.

  In Patent Document 2, air containing toner in the developing device is introduced into a pump through an intake tube using a pump, and is connected to an exhaust means for discharging the air in the pump through an exhaust tube via the exhaust tube. An image forming apparatus including a tank and a filter-like toner collecting unit that collects toner by escaping air from air that is attached so as to close the opening of the tank and is discharged by an exhaust unit is disclosed.

  In the invention of Patent Document 1, the effective area of the depressurization filter is limited while moving the masking member, that is, the area of the depressurization filter that is limited in advance is further limited. .

  However, the air flow concentrates on the depressurization filter of the limited area, so the toner clogging of the depressurization filter occurs earlier, and the effective part of the filter is switched one by one. It has been difficult to extend the life of the entire filter.

  Here, in order to improve the depressurization performance of the depressurization filter, as a matter of course, means for devising the material of the filter is effective, but as the simplest method, it is conceivable to increase the effective area. However, as shown in FIG. 7, in the invention of Patent Document 1, it is difficult to set the effective area of the pressure relief filter beyond the size of the developing device itself, and the effective area that can be set by the size of the developing device main body. Will be limited.

  Also, after the effective part of the depressurization filter has been used up, replacement work of the depressurization filter occurs, but since the developing device and the depressurization filter are integrated, the developing device must be replaced when replacing the depressurization filter. It was necessary to remove the image forming apparatus once and replace it later.

  Moreover, in patent document 1, since a masking member hold | maintains a pressure release filter, it is necessary to remove a masking member once for attachment / detachment replacement | exchange of a pressure release filter, and the replacement | exchange operation | work of a pressure release filter is difficult.

  Japanese Patent Application Laid-Open No. 2004-228561 uses a pump to positively suck out excess toner and perform pressure release and toner collection. However, it is necessary to provide a pump mechanism in the developing device, and the structure is complicated. At the same time, there was a problem of high costs.

  Therefore, the present invention enables the effective area of the pressure release filter to be increased with a simple configuration, achieves a longer life of the pressure release filter, and improves the maintainability of the pressure release filter. It is an object of the present invention to provide an image forming apparatus including the apparatus and the developing device.

  In order to achieve such an object, a developing device according to the present invention is a developing device that stirs a developer contained in a developing tank to frictionally charge the developer and supplies the electrostatic latent image on a latent image carrier. And the pressure relief filter unit provided separately from the opening of the developing tank provided in the main body of the developing device communicates with the pressure relief filter unit through a ventilation path. The unit is provided with a pressure relief filter that suppresses the pressure rise in the developing tank.

  According to the present invention, it is possible to increase the effective area of the pressure relief filter with a simple configuration, to realize a longer life of the pressure relief filter and to improve the maintainability of the pressure relief filter. .

1 is an external configuration diagram showing an embodiment of a developing device according to the present invention (first embodiment). It is sectional drawing of a developing device and a photoreceptor. It is an external appearance block diagram which shows other embodiment of a developing device (2nd embodiment). It is an external appearance block diagram which shows other embodiment of a developing device (3rd embodiment). 1 is a schematic configuration diagram illustrating a basic configuration of an image forming apparatus. 1 is an external configuration diagram showing an embodiment of an image forming apparatus according to the present invention. It is an external appearance block diagram of the conventional image development apparatus.

  Hereinafter, a configuration according to the present invention will be described in detail based on the embodiment shown in FIGS.

(First embodiment)
The developing device according to the present embodiment is a developing device (development) in which a developer contained in a developing tank (developing casing 30) is frictionally charged by stirring and supplied to an electrostatic latent image on a latent image carrier. A pressure relief filter unit (pressure relief) provided separately from the main body from an opening (opening 25) of a developing tank provided in the main body (main body 21) of the developing device. The filter unit 23) communicates with the air passage (air passage 22), and the pressure relief filter unit is provided with a pressure relief filter (pressure relief filter 24) that suppresses the pressure increase in the developing tank. .

  FIG. 1 is an external configuration diagram of a developing device according to the present embodiment, and FIG. 2 is a cross-sectional view showing the developing device together with a photoreceptor.

  As shown in FIG. 1, the developing device 20 has a main body 21 having a developing tank or the like communicated with a pressure relief filter unit 23 which is a separate part through a ventilation path 22 for exhausting air in the developing tank. A pressure release filter 24 is installed in the release filter unit 23.

  A depressurizing filter 24 provided on the constituent surface of the depressurizing filter unit 23 filters and attaches fine floating matters such as toner and dust in the developing tank of the developing device 20, and develops the atmospheric pressure by internal stirring. The air inside is discharged to reduce the pressure in the developing tank.

  Since the pressure relief filter unit 23 is not a main body 21 of the developing device 20 but a separate structure, the effective area is uniquely designed without being influenced by the size of the main body 21 of the developing device 20. Is possible.

  Since the depressurizing filter unit 23 can be provided with a depressurizing filter 24 having a large effective area, when compared with a smaller depressurizing filter, the time to reach the clogged state becomes longer and the filter replacement is accordingly performed. The number of times can be reduced.

  A configuration example of the main body 21 of the developing device 20 will be described with reference to FIG. As shown in FIG. 2, a developing device 20 is opposed to the photosensitive drum 11 that is a latent image carrier. The developing device 20 includes a developing casing (developing tank) 30 that contains a carrier and toner, and the carrier (not shown) and the toner (not shown) in the developing casing 30 are agitated by a paddle wheel 31 and the periphery of the developing sleeve 32. Supplied to the surface.

  The carrier and toner supplied to the peripheral surface of the developing sleeve 32 are transported while being carried on the outer peripheral surface, and in the course of this transporting, excess is scraped off by the doctor blade 33 and thinned so as to be suitable for development. The

  The carrier and toner on the developing sleeve 32 are used to visualize the electrostatic latent image formed on the photosensitive drum 11 in the developing region 34.

  On the other hand, the carrier and toner scraped off by the doctor blade 33 are guided toward the separator 35, and are dropped toward the paddle wheel 31 while being conveyed in the axial direction of the developing sleeve 32 by the fins 36 of the separator. .

  Further, a part of the carrier and the toner is guided toward the conveying screw 37 and is dropped toward the paddle wheel 31 while being conveyed in the direction opposite to the conveying direction of the fins 36.

  Further, the toner is supplied into the developing casing 30 by a toner supply unit 38 attached to the developing casing 30.

  The toner is conveyed to the supply roller 40 by the agitator 39 inside the toner supply unit 38 and is supplied into the developing casing 30 by the rotation of the supply roller 40.

  An opening 25 is formed in the upper wall of the developing casing 30, and the opening 25 is connected to a separate pressure relief filter unit 23 through the ventilation path 22. Note that the configuration of the main body 21 of the developing device 20 shown in FIG. 2 is an example, and is not limited thereto. Further, the developing device is not limited to the two-component developing type, and may be a one-component developing type developing device.

  The developing device 20 according to the present embodiment includes a pressure relief filter unit 23 that is connected to the main body portion 21 (development tank) through the ventilation path 22 and is provided as a separate part. Since the size (effective area) can be set with a certain degree of freedom without being influenced by the size of the main body 21 of the developing device 20, a filter having a larger pressure (effective area) and high depressurization effect should be set. Will be able to. Thus, by enlarging the effective area of the depressurizing filter 24, it is possible to extend the filter life by delaying the progress of the filter clogging.

  Further, the vent passage 22 is communicated with a pressure relief filter unit 23 provided as a separate body (in other words, the location of the pressure relief filter 24 is changed through the vent passage 22). A mechanism is unnecessary, and the configuration of the developing device 20 is not complicated, and can be easily realized at low cost.

  In addition, in the configuration in which the main body of the developing device and the pressure release filter are integrally disposed, when replacing the pressure release filter, it is necessary to remove the development device from the image forming apparatus and then perform the replacement work. However, in the developing device 20 according to the present embodiment, since the main body 21 and the pressure release filter 24 are separate, the pressure release filter 24 can be easily replaced without directly handling the development device 20. Therefore, the maintainability of the pressure relief filter 24 can be improved.

(Second embodiment)
Next, another embodiment of the image forming apparatus according to the present invention will be described. In addition, the description about the same point as the said embodiment is abbreviate | omitted.

  FIG. 3 shows an external configuration diagram of the developing device 20 of the second embodiment. As shown in FIG. 3, along with the pressure release filter (also referred to as the first pressure release filter) 24 of the pressure release filter unit 23, the pressure release filter (also referred to as the second pressure release filter) is also provided on the main body 21 side of the developing device 20. It is preferable to provide. The depressurizing filter 26 may be of the same configuration as the conventional one, and an exhaust port (opening) is provided at the illustrated position of the developing tank of the main body 21, and the depressurizing filter 26 is provided at the exhaust port. It only needs to be installed.

  In this way, by providing the conventional pressure release filter 26 provided integrally with the main body 21 of the developing device 20 and having a plurality of pressure release filters 24, 26, a higher pressure release effect is achieved. Can be obtained.

(Third embodiment)
FIG. 4 is an external configuration diagram of the developing device 20 according to the third embodiment. As shown in FIG. 4, the pressure release filter 24 of the pressure release filter unit 23 is preferably provided in the pressure release filter unit 23 so as to be detachable.

  As described above, the pressure relief filter unit 23 configured separately from the main body 21 of the developing device 20 can increase the effective area so that the life of the pressure relief filter 24 can be extended. If it is not exchanged, it does not guarantee a permanent pressure relief effect. Therefore, by making the pressure relief filter 24 provided in the pressure relief filter unit 23 attachable / detachable and replaceable, it is possible to improve the convenience of maintenance and enable permanent use.

(Image forming device)
By using the image forming apparatus 1 including the developing device 20 according to the embodiment described above, an image forming apparatus including the developing device having the above-described effects can be provided.

  FIG. 5 is a schematic configuration diagram illustrating the overall configuration of a tandem type color copier that is an embodiment of the image forming apparatus. The basic configuration and operation of the image forming apparatus will be described with reference to FIG.

  In FIG. 5, 1 is an image forming apparatus main body, 2 is a writing unit that emits laser light based on input image information, 3 is a document conveying unit that conveys a document D to a document reading unit 4, and 4 is image information of the document D. A document reading unit to be read, 7 is a paper feed unit that accommodates a recording material P such as transfer paper, 9 is a registration roller that adjusts the conveyance timing of the recording material P, and 11Y, 11M, 11C, and 11BK are each color (yellow, magenta, Cyan and black) are formed on the photosensitive drums, 12 is a charging unit for charging the photosensitive drums 11Y, 11M, 11C, and 11BK, and 20 is the photosensitive drums 11Y, 11M, 11C, and 11BK. A developing unit (developing device) 14 for developing the formed electrostatic latent image is a transfer unit that transfers the toner images formed on the photosensitive drums 11Y, 11M, 11C, and 11BK on the recording material P in an overlapping manner. Bias roller (primary transfer bias roller), 15 denotes the photosensitive drums 11Y, 11M, 11C, a cleaning unit for collecting the untransferred toner on 11BK.

  Also, 16 is an intermediate transfer belt cleaning unit for cleaning the intermediate transfer belt 17, 17 is an intermediate transfer belt on which toner images of a plurality of colors are transferred, and 18 is a color toner image on the intermediate transfer belt 17 on the recording material P. A secondary transfer bias roller 13 for transferring the toner image onto the recording material P indicates a fixing device for fixing the toner image on the recording material P.

  Hereinafter, an operation during normal color image formation in the image forming apparatus 1 will be described. First, the document D is transported from the document table in the direction of the arrow in the drawing by the transport rollers of the document transport unit 3 and placed on the contact glass 5 of the document reading unit 4. Then, the document reading unit 4 optically reads the image information of the document D placed on the contact glass 5. Specifically, the document reading unit 4 scans the image of the document D on the contact glass 5 while irradiating light emitted from an illumination lamp. Then, the light reflected by the document D is imaged on the color sensor via the mirror group and the lens. The color image information of the document D is read for each RGB (red, green, blue) color separation light by the color sensor, and then converted into an electrical image signal. Further, color conversion processing, color correction processing, spatial frequency correction processing, and the like are performed by the image processing unit based on the RGB color separation image signals to obtain yellow, magenta, cyan, and black color image information.

  Then, the image information of each color of yellow, magenta, cyan, and black is transmitted to the writing unit 2. The writing unit 2 emits laser light (exposure light) based on the image information of each color toward the corresponding photosensitive drums 11Y, 11M, 11C, and 11BK.

  On the other hand, the four photosensitive drums 11Y, 11M, 11C, and 11BK are rotated clockwise in FIG. First, the surfaces of the photosensitive drums 11Y, 11M, 11C, and 11BK are uniformly charged at a portion facing the charging unit 12 (charging process). Thus, a charged potential is formed on the photosensitive drums 11Y, 11M, 11C, and 11BK. Thereafter, the charged surfaces of the photosensitive drums 11Y, 11M, 11C, and 11BK reach the irradiation positions of the respective laser beams.

  In the writing unit 2, laser light corresponding to the image signal is emitted from the four light sources corresponding to each color. Each laser beam passes through a different optical path for each color component of yellow, magenta, cyan, and black (exposure process).

  Laser light corresponding to the yellow component is irradiated on the surface of the first photosensitive drum 11Y from the left side of the drawing. At this time, the yellow component laser light is scanned in the rotation axis direction (main scanning direction) of the photosensitive drum 11Y by a polygon mirror that rotates at high speed. Thus, an electrostatic latent image corresponding to the yellow component is formed on the photosensitive drum 11Y charged by the charging unit 12.

  Similarly, the laser beam corresponding to the magenta component is irradiated onto the surface of the second photosensitive drum 11M from the left side of the paper, and an electrostatic latent image corresponding to the magenta component is formed. The cyan component laser light is applied to the surface of the third photosensitive drum 11C from the left side of the paper, and an electrostatic latent image of the cyan component is formed. The black component laser beam is applied to the surface of the fourth photosensitive drum 11BK from the left side of the paper, and an electrostatic latent image of the black component is formed.

  Thereafter, the surfaces of the photosensitive drums 11Y, 11M, 11C, and 11BK on which the electrostatic latent images of the respective colors are formed reach the positions facing the developing unit 20, respectively. Then, the respective color toners are supplied from the developing units 20 onto the photosensitive drums 11Y, 11M, 11C, and 11BK, and the latent images on the photosensitive drums 11Y, 11M, 11C, and 11BK are developed (developing step).

  Thereafter, the surfaces of the photoconductive drums 11Y, 11M, 11C, and 11BK after the development process reach the opposed portions to the intermediate transfer belt 17, respectively. Here, a transfer bias roller 14 is installed at each facing portion so as to contact the inner peripheral surface of the intermediate transfer belt 17. Then, the toner images of the respective colors formed on the photosensitive drums 11Y, 11M, 11C, and 11BK are sequentially superimposed and transferred onto the intermediate transfer belt 17 at the position of the transfer bias roller 14 (primary transfer process). .

  Then, the surfaces of the photosensitive drums 11Y, 11M, 11C, and 11BK after the transfer process reach positions facing the cleaning unit 15, respectively. Then, the untransferred toner remaining on the photosensitive drums 11Y, 11M, 11C, and 11BK is collected by the cleaning unit 15 (cleaning process).

  Thereafter, the surfaces of the photoconductive drums 11Y, 11M, 11C, and 11BK pass through a static elimination unit (not shown), and a series of image forming processes on the photoconductive drums 11Y, 11M, 11C, and 11BK is completed.

  On the other hand, the intermediate transfer belt 17 on which the toners of the respective colors on the photoconductive drums 11Y, 11M, 11C, and 11BK are transferred (carried) are run in the clockwise direction in the drawing and are connected to the secondary transfer bias roller 18. Reach the opposite position. Then, a color toner image carried on the intermediate transfer belt 17 is transferred onto the recording material P at a position facing the secondary transfer bias roller 18 (secondary transfer step).

  Thereafter, the surface of the intermediate transfer belt 17 reaches the position of the intermediate transfer belt cleaning unit 16. Then, the untransferred toner adhered on the intermediate transfer belt 17 is collected by the intermediate transfer belt cleaning unit 16, and a series of transfer processes in the intermediate transfer belt 17 is completed.

  Here, the recording material P conveyed between the intermediate transfer belt 17 and the secondary transfer bias roller 18 (secondary transfer nip) is conveyed from the paper supply unit 7 via the registration roller 9 and the like. is there.

  Specifically, the recording material P fed by the paper feeding roller 8 from the paper feeding unit 7 that stores the recording material P is guided to the registration roller 9 after passing through the conveyance guide. The recording material P that has reached the registration roller 9 is conveyed toward the secondary transfer nip at the same timing.

  Then, the recording material P to which the full color image has been transferred is guided to the fixing device 13 by the conveyance belt. In the fixing device 13, the color image (toner) is fixed on the recording material P at the nip between the fixing belt and the pressure roller.

  The recording material P after the fixing process is discharged as an output image to the outside of the apparatus main body 1 by a paper discharge roller, and a series of image forming processes is completed.

  Here, as shown in FIG. 6, the pressure release filter 24 of the pressure release filter unit 23 of the developing device 20 according to the above embodiment is provided so as to be formed on the same surface as the exterior plate surface 19 of the image forming apparatus 1. It is preferable. In addition, the position of the pressure release filter unit 23 can be set to a desired position by changing the shape of the ventilation path 22 and turning it around.

  In this way, by installing the pressure release filter unit 23 in accordance with the exterior plate surface 19 of the image forming apparatus 1, conventionally, when the pressure release filter 24 is maintained and operated, the protective door of the image forming apparatus 1 is opened and the developing device is opened. It is possible to easily clean the depressurizing filter 24 and the like, which could not be performed unless the 20 is taken out, from the side of the exterior plate surface 19, thereby improving the maintainability. In addition, as shown in the third embodiment, when the pressure release filter 24 is configured to be detachable, the replacement work can be easily performed.

  The above-described embodiment is a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Writing part 3 Original conveyance part 4 Original reading part 5 Contact glass 7 Paper feed part 8 Paper feed roller 9 Registration roller 11Y, 11M, 11C, 11BK Photosensitive drum 12 Charging part 13 Fixing apparatus 14 Transfer bias roller ( Primary transfer bias roller)
DESCRIPTION OF SYMBOLS 15 Cleaning part 16 Intermediate transfer belt cleaning part 17 Intermediate transfer belt 18 Secondary transfer bias roller 19 Outer plate surface 20 Developing device 21 Main body part 22 Air passage 23 Pressure release filter unit 24 Pressure release filter (first pressure release filter)
25 Opening 26 Pressure Release Filter (Second Pressure Release Filter)
30 Developing casing 31 Paddle wheel 32 Developing sleeve 33 Doctor blade 34 Developing area 35 Separator 36 Fin 37 Conveying screw 38 Toner supply unit 39 Agitator 40 Supply roller D Document P Recording material

Japanese Patent Laid-Open No. 9-236980 Japanese Patent No. 4137166

Claims (4)

A developing device that stirs a developer contained in a developing tank and frictionally charges the developer to supply the electrostatic latent image on the latent image carrier,
From the opening of the developing tank provided in the main body of the developing device to the pressure relief filter unit provided as a separate body from the main body through the ventilation path,
A developing device, wherein the pressure relief filter unit is provided with a pressure relief filter that suppresses an increase in pressure in the developing tank. The pressure release filter of the pressure release filter unit as a first pressure release filter,
The developing device according to claim 1, wherein a second pressure releasing filter is provided in the main body.   The developing device according to claim 1, wherein the pressure release filter of the pressure release filter unit is detachably provided in the pressure release filter unit. An image forming apparatus comprising the developing device according to claim 1,
The image forming apparatus, wherein the pressure releasing filter of the pressure releasing filter unit is provided on the same surface as an exterior plate surface of the image forming apparatus.

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