JP2001356602A - Developing device and image forming device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device by which the occurrence of lumped toner due to the stagnation of an air flow at the inside of a developing unit is prevented. SOLUTION: The developing device 1 is driven until the fixing device of an image forming device is started at the time of turning on a power source or after the completion of image-forming, and also developer is made to overflow from a developer guide 77 by closing an aperture part 78 at the last end of the developer guide 77 by a shutter 22, so that stuck and heaped toner at the end surface of the developer guide 77 is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used in an image forming apparatus such as a copying machine, a facsimile, a printer, etc., and more particularly, to a developing device using a two-component developer composed of a toner and a carrier.

[0002]

2. Description of the Related Art Conventionally, for example, toner supplied from a toner replenishing section is mixed with an existing developer by a developer mixing member (for example, an elliptical plate), and the developer is mixed with a developer stirring and conveying member (for example, a stirring paddle). ), A developer carrier (eg, a developing sleeve) provided to face the latent image carrier
The developer is conveyed to the peripheral surface and carried on the peripheral surface, and the excess developer among the peripheral surface is scraped by a developer blade as a developer regulating member disposed with a predetermined gap with respect to the developing sleeve. A developing device is known in which a developer is supplied to a latent image carrier to develop a latent image after regulating the thickness of the developer on the developing sleeve to a predetermined thickness. Further, in this type of developing device, in order to circulate the developer inside the developing device, the developer regulated by the doctor blade is used as a developer movement regulating member configured to return to the stirring paddle and the elliptical plate. For example, those provided with a separator are known.

As such a separator, for example,
A horizontal portion for receiving the developer regulated by the doctor blade, and a downwardly inclined portion; a plurality of fins as a developer deflecting guide member on the downwardly inclined portion; A gutter-shaped developer guide that takes in the developer and transports the taken-in developer in a direction opposite to the fins;
An opening provided at the end of the gutter-shaped developer guide for dropping the conveyed developer is known.

In such a separator, the developer regulated by the doctor blade is received by the horizontal portion, and flows down on the down-slope portion while being deflected and guided in the depth direction by the developer deflecting guide member to the stirring paddle. Is returned. On the other hand, at the rear end of the downflow slope, a part of the developer is taken in, and the taken-out developer is guided to a transport screw that transports the developer in a direction opposite to the deflection guide member (front side), and is transported by the transport screw. The structure is such that the developer is dropped onto an elliptical plate from an opening provided at the end. That is, this is a so-called cross-mixing method in which developers are transported in opposite directions.

In the conventional developing device as described above, the internal pressure of the developing device rises due to the pumping action of the developer on the developing sleeve, and toner scatters from an opening formed opposite the latent image carrier. As a result, in-machine contamination of the image forming apparatus occurs, and a background stain of an image due to the contamination occurs.

Therefore, in a conventional developing device, for example, a pressure release hole with a filter is provided in at least one portion of a developing device casing to prevent the internal pressure of the developing device from becoming excessively high. Some measures have been taken to prevent toner scattering.

[0007]

However, the present inventor has found that even if a pressure release hole with a filter is provided in consideration of the scattering of toner due to an increase in the internal pressure of the developing device, an image stain like a dropping image will occur. confirmed. Examination of the cause revealed the following. That is, even if the toner is prevented from being scattered outside the developing device due to an increase in the developing device internal pressure, in the conventional developing device, the rotation of the elliptical plate, the stirring paddle, the developing sleeve, and the like, and the developing device internal pressure and the developing device external pressure The air flow is generated in a predetermined direction due to the difference between the air flow and the air flow, and the air flow may contain floating toner that does not mix with the developer with sufficient charge. Then, depending on the shape of various members such as a separator provided in the developing device, stagnation occurs in the above-described air flow, and the stagnation of the air flow causes the floating toner to stay in a certain place and to be formed on the members such as the separator. The toner adheres and accumulates to form a lump, and the lump of the toner falls into the developer and is used for development, thereby causing image stains such as a drop-off state.

In particular, in a developing device provided with a toner replenishing unit near the separator, the floating toner immediately after replenishment tends to adhere to and accumulate on the outer surface of the screw guide for conveying the separator. If the toner falls into the developer, there is a possibility that an image stain like a drop-off may occur. In addition, the lower surface of the separator is a hollow portion, and air stagnation tends to occur in this hollow portion. Therefore, an air vent hole communicating from the lower part to the upper part of the separator falling slope is provided to prevent stagnation of air, but it has not yet been possible to completely prevent toner from adhering.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a developing device capable of preventing generation of a mass of toner due to stagnation of air flow in a developing device.

[0010]

According to a first aspect of the present invention, there is provided a developing device for supplying a developer to a latent image carrier having a latent image formed on a surface thereof in order to achieve the above object. A developer carrying member, a developer stirring / conveying member for carrying the developer in the direction of the developer carrying member, and scraping excess developer on the developer carrying member to remove the developer on the developer carrying member. A developer regulating member that regulates the developer to a predetermined thickness, and a developer that is scraped by the developer regulating member, is received by a receiving portion, and the developer received by the receiving portion is dropped to the developer stirring and conveying member. A downwardly inclined portion, a plurality of inclined fins as a developer deflecting guide member provided on the downwardly inclined portion, and a part of the downwardly inclined portion and a part of the developer taken in, and the developer taken in Gutter guide for transporting the gutter in the opposite direction to the fins, and a gutter-shaped guide terminal In a developing device comprising: a developer guide member provided with an opening for dropping the conveyed developer; and a conveyance screw for conveying the developer in the gutter-shaped guide, an end of the gutter-shaped guide is provided. An opening and closing means for opening and closing the opening is provided. That is, the opening and closing of the gutter-shaped guide terminal opening can be freely opened and closed, the developer conveyed by the conveyance screw is closed by closing the opening, and the developer overflows from the gutter-shaped guide to both sides. Due to the overflow of the agent, the toner mass attached and accumulated on the outside of the guide is washed away by cleaning.
Prevents generation of toner lumps.

According to a second aspect of the present invention, there is provided a developing device for supplying a developer to a latent image carrier having a latent image formed on a surface thereof. A developer agitating / conveying member for conveying the developer in the direction of the developer carrier, and a developer on the developer carrier being scraped by scraping off excess developer on the developer carrier to a predetermined thickness; A developer regulating member, a falling slope for receiving the developer scraped by the developer regulating member at a receiving portion, and dropping the developer received at the receiving portion to the developer stirring and conveying member,
A plurality of inclined fins as a developer deflecting guide member provided on the downflow inclined portion; and a part of the downflow inclined portion, in which a part of the developer is taken in, and the taken-in developer is moved in a direction opposite to the fin. A developer guide member having a gutter-shaped guide for transporting the developer, an opening provided at the end of the gutter-shaped guide for dropping the transported developer, and transporting the developer in the gutter-shaped guide. And a driving device for driving only the developer stirring / conveying member. That is, in this developing device, the developing sleeve and the like are stopped and the stirring paddle is rotated without pumping the developer, whereby the developer hits the bottom surface of the separator by centrifugal force, whereby the toner adhered and deposited on the bottom surface. The cleaning is performed by scraping the lumps to prevent the generation of toner lumps.

According to a third aspect of the present invention, there is provided a developing device for supplying a developer to a latent image carrier having a latent image formed on a surface thereof. A developer agitating / conveying member for conveying the developer in the direction of the developer carrier, and a developer on the developer carrier being scraped by scraping off excess developer on the developer carrier to a predetermined thickness; A developer regulating member, a falling slope for receiving the developer scraped by the developer regulating member at a receiving portion, and dropping the developer received at the receiving portion to the developer stirring and conveying member,
A plurality of inclined fins as a developer deflecting guide member provided on the downflow inclined portion; and a part of the downflow inclined portion, in which a part of the developer is taken in, and the taken-in developer is moved in a direction opposite to the fin. A developer guide member having a gutter-shaped guide for transporting the developer, an opening provided at the end of the gutter-shaped guide for dropping the transported developer, and transporting the developer in the gutter-shaped guide. In a developing device provided with a conveying screw, an opening / closing means for opening / closing a terminal opening of the gutter-shaped guide and a driving means for driving only the developer stirring / conveying member are provided.

According to a fourth aspect of the present invention, there is provided an image forming apparatus including the developing device according to the first aspect, wherein the opening / closing means of the terminal opening of the gutter-shaped guide is fixed when power is turned on. It is characterized in that it is driven when the device is started up. That is, by controlling the opening / closing means for the opening at the end of the gutter-shaped guide at the time until the fixing device rises when the power is turned on, a part of the developer becomes floating toner,
Even if the floating toner adheres to and accumulates on the separator, the toner can be always cleaned to prevent the generation of a toner mass. In addition, by performing cleaning during the time until the fixing device starts up when the power is turned on, time is not wasted.

According to a fifth aspect of the image forming apparatus of the present invention, in the image forming apparatus having the developing device of the second aspect, a driving unit for driving only the developer stirring and conveying member is provided. It is characterized by being driven later. That is, even if a part of the developer becomes floating toner and the floating toner adheres and accumulates on the separator, it can be always cleaned to prevent the generation of the toner mass.

According to a sixth aspect of the present invention, there is provided an image forming apparatus comprising the developing device according to the third aspect, wherein the opening / closing means for the end opening of the gutter-like guide and the developer stirring and conveying are provided. A driving unit for driving only the members is driven when the fixing device starts up when the power is turned on and after the image formation is completed. That is, each time the image formation of one job is completed, the opening / closing means of the gutter-shaped guide terminal opening and the driving means for driving only the developer stirring / conveying member are controlled, so that the power of the facsimile or the printer is always turned on.
Even in the state, even if a part of the developer becomes floating toner and adheres to and accumulates on the separator, the developer is always cleaned to prevent generation of a toner mass.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. Hereinafter, an example in which the present invention is applied to a two-component developing device of an electrophotographic copying machine (hereinafter, referred to as a copying machine) which is an image forming apparatus will be described. FIG. 1 is a front view showing a schematic configuration of an embodiment of the developing device according to the present invention. The developing device 1 includes a developing device having an upper developing sleeve 2 and a lower developing sleeve 3 as a developer carrier provided so as to be partially exposed from an opening toward the photoconductor 100 as a latent image carrier. And a toner supply device 4. In the developing device of the developing device 1, in addition to the upper developing sleeve 2 and the lower developing sleeve 3, the developer contained in the developing device is stirred and supplied to the upper developing sleeve 2 and the lower developing sleeve 3. Stirring paddle 5 and doctor blade 6 for regulating the amount of developer on upper developing sleeve 2
The toner supplied from the toner replenishing device 4 and the separator 7 serving as a developer movement restricting member or a developer guide member for causing the developer regulated by the doctor blade 6 to flow down while being agitated side by side with the developer in the developing device. A plurality of elliptical plates 8 for mixing and stirring are provided.

The toner replenishing device 4 includes an agitator 9 for stirring and transporting the stored toner and a replenishing roller 10 which is rotated based on the result of detecting the toner concentration of the developer in the developing device and replenishes the toner in the developing device. It is provided. A seal holder 11 is provided on the downstream side of the doctor blade 6 in the rotation direction of the upper developing sleeve 2, and an inlet seal 12 is attached to the seal holder 11 so that the front end edge is lightly pressed against the surface of the photoconductor 100. The seal holder 11 and the inlet seal 12 constitute the upper part of the opening of the developing device. The inlet seal 12 has a thickness of, for example, 0.2 mm to 0.1 mm.
It is formed of an elastic plate made of 3 mm polyurethane rubber. The seal holder 11 is hung on an upper casing 13 which is a component of the developing device, and a lower edge of the lower casing 14 constitutes a lower portion of the opening of the developing device.

Further, in the developing device 1, the internal pressure of the developing device 1 is increased by the pumping action of the developer on the upper developing sleeve 2 and the lower developing sleeve 3 which are the developer carrying members, and the photosensitive member which is the latent image carrying member For example, in order to prevent a problem that toner scatters from an opening formed to face the image forming apparatus 100 and contaminates the inside of the apparatus or causes a stain on the background of an image, for example, at least one of the developing device casings may be used.
A pressure relief hole with a filter is provided at three places to prevent the internal pressure of the developing device from becoming excessively high. Specifically, a pressure release filter 15 that prevents toner from passing through is provided above the developing device 1 to prevent an excessive increase in pressure inside the developing device 1. As a result, it is possible to prevent the toner from scattering outside the developing device and the background contamination.

As the upper developing sleeve 2 and the lower developing sleeve 3, a known developing sleeve for transporting the developer in the form of a magnetic brush by magnetic force and rotation, for example, a rotating sleeve containing a plurality of fixed magnets is used. It is a developing sleeve.

The separator 7 includes a horizontal portion 71 for receiving the developer regulated by the doctor blade 6, and a falling slope 72 extending from the right edge of the horizontal portion 71 to the elliptical plate 8 and the stirring paddle 5. The horizontal portion 71 and the downward inclined portion 72 form a guide surface for guiding the movement of the developer.

FIG. 2A is a plan view of the separator 7, and FIG. 2B is a side view of the separator 7. As shown in FIG. 2, a plurality of fins 74 as a developer deflecting guide member and a plurality of cylindrical air vent holes 75 communicating from the lower part to the upper part of the falling inclined part 72 are formed in the falling inclined part 72 of the separator 7. It is provided. Furthermore, the inner part of the downflow slope 72 is
A take-out port 76 for taking out a part of the developer received by the horizontal portion 71 is provided. The take-out port 76 has a gutter-shaped developer guide 77 internally provided with a conveying screw 16 that conveys to the front side of the apparatus by rotating in a predetermined direction.
Connected to An opening 78 for dropping the developer is formed at the end of the developer guide 77 on the front side of the apparatus. The separator 7 is an integrally formed product made of, for example, a resin (ABS or the like), and has both ends at the front and rear side plates 20, 2.
1 is fixed to the developing device by screwing.

In the separator 7, the developer regulated by the doctor blade 6 is received by the horizontal portion 71, and a part of the developer passes through the intake 76 at the end of the falling slope 72 at the back side of the device, and the developer guide 77. It is led to. And
The developer is transported to the front side of the apparatus by the transport screw 16 in the developer guide 77, and falls from the opening 78 to the vicinity of the elliptical plate 8. On the other hand, the developer not taken in through the inlet 76 flows down while being deflected and guided in the predetermined direction by the fins 74 on the flow-down inclined portion 72 on the front side of the device with respect to the inlet 76, and the vicinity of the elliptical plate 8. And is returned into the developing device 1.

In the developing device 1, the rotation of the elliptical plate 8, the stirring paddle 5, the developing sleeves 2, 3 and the like,
The flow of air is generated in a predetermined direction due to the difference between the internal pressure of the developing device and the external pressure of the developing device, and floating toner which is not mixed with a sufficiently charged developer may be mixed in the air flow. Various members such as a separator 7 are provided in the developing device. Depending on the shape of these members, stagnation occurs in the flow of air. As described above, the toner adheres to and accumulates on members such as 7 to form a lump, and the lump of the toner falls into the developer and is used for development, thereby causing image drop-like image stains. It is. In particular, the floating toner immediately after replenishment easily adheres and accumulates on the separator and the outer surface of the guide of the conveying screw 16. According to the confirmation by the inventor of the present application, since the flow of the elliptic plate 8 due to the airflow is present in the portion of the developer guide 77, there is no occurrence of the toner adhesion in a lump. In addition, the lower surface of the separator 7 (the bottom-dot chain line portion) is a hollow portion, and air stagnation tends to occur in this hollow portion. Therefore, an air vent hole 75 communicating from the lower part to the upper part of the separator falling slope is provided to prevent air stagnation, but this does not completely prevent the toner from adhering.

Therefore, in the present embodiment, the following configuration is added. That is, the shutter 22 for opening and closing the opening 78 is provided near the lower surface of the opening 78. A compression spring 24 is provided on the end of the shutter 22 and the front side plate 21, and an eccentric cam 23 contacts the opposite surface to form an opening / closing mechanism, whereby the shutter 22 slides in the direction of the arrow. ing. When the eccentric cam 23 is rotated by 180 ° by the stepping motor 25,
The shutter 22 is opened and closed. The stepping motor 25 is locked to the front side plate 20 with screws.

FIG. 3 is a perspective view showing a structure for independently driving the stirring paddle 5, and a motor 26 is directly connected to the shaft end of the stirring paddle 5 individually. According to this configuration, it is possible to clean the adhesion of the toner generated in the space where the stagnation of the air flow occurs.

That is, in the apparatus of the present embodiment, the developing device 1 is driven until the fixing device of the image forming apparatus starts up when the power is turned on or after the image formation is completed, and the opening portion 78 at the end of the developer guide 77 is closed by the shutter 22. As a result, the developer overflows from the developer guide 77, and the toner adhered and accumulated on the side surface of the developer guide 77 is cleaned. Further, by stopping the developing device 1 and driving only the stirring paddle 5 by the motor 26, the developer can be hit against the bottom surface of the separator by centrifugal force.
The toner mass adhering and accumulating on the bottom surface is scraped and cleaned.

[0027]

As described above, the developing device according to the first aspect of the present invention is capable of freely opening and closing the gutter-shaped guide terminal opening which is a part of the separator, and closing the opening. Block the developer conveyed by the conveying screw, and overflow the developer from the gutter-shaped guide to both sides, so that the toner mass attached and accumulated on the outside of the guide is washed away by cleaning, and the generation of the mass of the developer is reduced. Thus, there is an effect that it is possible to prevent the occurrence of local image fouling-like image stains caused by using a massive developer for development.

As described above, the developing device according to the second aspect of the present invention stops the developing sleeve and the like and rotates only the stirring paddle without pumping up the developer. Is pressed against the separator bottom surface by centrifugal force, and the toner mass adhered to and accumulated on the bottom surface can be scraped off and cleaned.As a result, the generation of a mass of the developer can be prevented, so that the mass of the developer is used for development. This has the effect of preventing the occurrence of local dirt-like image stains.

As described above, the developing device according to the third aspect of the present invention enables the opening and closing of the gutter-shaped guide terminal opening which is a part of the separator, and conveys the container by closing the opening. By blocking the developer conveyed by the screw and overflowing the developer from both sides of the gutter-shaped guide, the toner mass attached and deposited on the outside of the guide is washed away by cleaning, and the developing sleeve and the like are stopped. By rotating only the stirring paddle without pumping up the developer, the developer can be hit against the bottom of the separator by centrifugal force, and the toner lump adhering to the bottom and accumulated can be scraped and cleaned. Cleaning can be performed before stagnation of the air flow occurs in the developing unit and toner clumps are generated. There is an effect that can provide.

According to a fourth aspect of the present invention, there is provided an image forming apparatus comprising:
As described above, by driving the opening / closing means of the terminal opening of the gutter-shaped guide at the time of startup of the fixing device at the time of turning on the power, the opening of the terminal of the gutter-shaped guide at the time until startup of the fixing device at the time of turning on the power. By controlling the opening / closing means, a part of the developer becomes floating toner, and even if the floating toner adheres and accumulates on the separator, it can be always cleaned to prevent the generation of toner clumps, By performing cleaning during the time until the fixing device starts up when the power is turned on, there is an effect that time is not wasted.

According to a fifth aspect of the present invention, there is provided an image forming apparatus comprising:
As described above, by driving the driving unit that drives only the developer stirring and conveying member after the end of image formation,
Even if a part of the developer becomes floating toner, even if the floating toner adheres and accumulates on the separator, there is an effect that the toner can be always cleaned and the generation of the toner mass can be prevented.

An image forming apparatus according to a sixth aspect of the present invention comprises:
As described above, the driving means for driving only the opening / closing means of the terminal opening of the gutter-shaped guide and the developer stirring / conveying member is driven when the fixing device starts up when the power is turned on and after image formation is completed. Each time the image formation is completed, the opening / closing means of the gutter-shaped guide terminal opening and the driving means for driving only the developer stirring / conveying member are controlled, respectively, so that even when the power of the facsimile or the printer is always on, a part of the developer is Even if the toner adheres and accumulates on the separator as floating toner, there is an effect that the toner is always cleaned to prevent the generation of a toner mass.

[Brief description of the drawings]

FIG. 1 is a front view illustrating a schematic configuration of an embodiment of a developing device according to the present invention.

FIG. 2 is a plan view (A) and a side view (B) of a separator of the apparatus of FIG.

FIG. 3 is a perspective view showing a configuration for independently driving a stirring paddle of the apparatus of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Developing device 2 Upper developing sleeve 3 Lower developing sleeve 4 Toner supply device 5 Stirring paddle 6 Doctor blade 7 Separator 8 Oval plate 9 Agitator 10 Supply roller 11 Seal holder 12 Inlet seal 13 Upper casing 14 Lower casing 15 Depressurizing filter 16 Conveying screw 20, 21 Front / rear side plate 22 Shutter 23 Eccentric cam 24 Compression spring 25 Stepping motor 26 Motor 71 Horizontal portion 72 Downflow inclined portion 74 Fin 75 Air vent hole 76 Extraction port 77 Developer guide 78 Opening 100 Photoconductor

Claims (6)

[Claims] 1. A developer carrier for supplying a developer to a latent image carrier having a latent image formed on a surface thereof, a developer stirring / transporting member for transporting the developer toward the developer carrier, and A developer regulating member for scraping off excess developer on the developer carrier and regulating the developer on the developer carrier to a predetermined thickness; and receiving a developer scraped by the developer regulating member. Receiving portion, a falling inclined portion for dropping the developer received by the receiving portion to the developer stirring and conveying member, and a plurality of inclined fins as a developer deflecting guide member provided on the flowing inclined portion. A gutter-shaped guide which is a part of the falling slope and takes in a part of the developer, and conveys the taken-in developer in a direction opposite to the fins; A developer guide member having an opening for dropping the developer; What is claimed is: 1. A developing device comprising: a conveying screw for conveying a developer in a gutter-shaped guide; and an opening / closing means for opening and closing a terminal opening of the gutter-shaped guide. 2. A developer carrier for supplying a developer to a latent image carrier having a latent image formed on a surface thereof, a developer stirring and conveying member for conveying the developer toward the developer carrier, A developer regulating member for scraping off excess developer on the developer carrier and regulating the developer on the developer carrier to a predetermined thickness; and receiving a developer scraped by the developer regulating member. Received by the department,
A falling slope for dropping the developer received by the receiving portion to the developer stirring and conveying member; a plurality of slant fins provided on the falling slope as a developer deflecting guide member; A gutter-shaped guide which is a part of the part and takes in a part of the developer, and conveys the taken-in developer in a direction opposite to the fins; and a developer provided at the end of the gutter-shaped guide drops the conveyed developer. In a developing device including a developer guide member having an opening for causing the developer to flow and a transport screw for transporting the developer in the gutter-like guide, a driving unit that drives only the developer stirring transport member is provided. A developing device. 3. A developer carrier for supplying a developer to a latent image carrier having a latent image formed on a surface thereof, a developer stirring / conveying member for transporting the developer toward the developer carrier, and A developer regulating member for scraping off excess developer on the developer carrier and regulating the developer on the developer carrier to a predetermined thickness; and receiving a developer scraped by the developer regulating member. Receiving portion, a falling inclined portion for dropping the developer received by the receiving portion to the developer stirring and conveying member, and a plurality of inclined fins as a developer deflecting guide member provided on the flowing inclined portion. A gutter-shaped guide which is a part of the falling slope and takes in a part of the developer, and conveys the taken-in developer in a direction opposite to the fins; A developer guide member having an opening for dropping the developer; In a developing device having a transport screw for transporting the developer in the gutter-shaped guide, an opening / closing means for opening and closing the terminal opening of the gutter-shaped guide and a driving means for driving only the developer stirring / conveying member are provided. A developing device, characterized in that: 4. An image forming apparatus comprising the developing device according to claim 1, wherein an opening / closing means for an end opening of the gutter-shaped guide is driven when the fixing device starts up when power is turned on. 5. An image forming apparatus comprising the developing device according to claim 2, wherein a driving unit for driving only the developer stirring and conveying member is driven after completion of image formation. 6. An image forming apparatus provided with a developing device according to claim 3, wherein the opening / closing means for opening the terminal opening of the gutter-shaped guide and the driving means for driving only the developer stirring / conveying member are provided in the fixing device when the power is turned on. An image forming apparatus which is driven at the time of startup and after completion of image formation.