JP3568383B2 - Image forming device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus, and in particular, supplies toner transferred by a screw pump to an electrostatic latent image formed on an image carrier in an electrophotographic system as a mixture with a gas from a position distant from a developing position. The present invention relates to an image forming apparatus such as a printer, a facsimile machine, a copying machine, or a multifunction machine for forming an image by using the image forming apparatus.
[0002]
[Prior art]
In an electrophotographic image forming apparatus such as a printer, a facsimile machine, a copying machine, or a multifunction machine using a dry one-component or two-component dry toner, the image is transferred onto a transfer body once while being transferred onto a photoreceptor. After the unremoved toner is collected by the cleaning unit, the image is formed by recycling development in which the toner is returned to the developing device and reused.
It is known that a toner of a developer is circulated and supplied to a developing section by a pump using a gas flow (see Japanese Patent Publication No. 63-3308).
FIG. 4 is an exploded perspective view showing a conventional configuration of the toner recycling mechanism, and FIG. 5 is a sectional view showing a configuration around a screw pump. In the figure, toner remaining on the image carrier 101, which is a drum-shaped photosensitive member, or on a belt-shaped transfer member (not shown) is collected and reused by the cleaning blade 107a of the cleaning unit 107. In this case, the collected toner discharged from the discharge pipe 107b of the cleaning unit 107 is dropped into the horizontal conveying screw case 108a via the connecting means 108, and the rotational driving force of the driving motor 109 is transmitted to the pulley of the rotational driving force transmitting means 109a. To the horizontal transport screw 108b in the horizontal transport screw case 108a via the belt, and rotate integrally with the rotor 103b in the stator 103a held by the holder 103c of the screw pump 103, so that the collected toner enters the stator 103a. And send.
The rotation of the rotor 103b in the stator 103a constituting the screw pump 103 causes the toner to be pushed out of the stator 103a through the outlet 103d and into the air-fuel mixture transporting means 105 connected to the outlet 103d. Air to be collected and circulated from the developing device 102 is put into the screw pump 103 through the air transfer pipe 104a, is sent to the air-fuel mixture conveying means 105 as an air-fuel mixture, and is conveyed to the hopper 102a of the developing device 102. Then, the air sucked by the air pump 104 is sucked from the hopper 102a of the developing device 102 to prevent the toner from being scattered due to pressure release of the hopper 102a of the developing device 102. Almost no circulation path Forming, an image forming apparatus for forming an image have been proposed from the same applicant of the inventor and supplied from a position away toner from the developing position to the developing device 102.
However, in the conventional image forming apparatus, the air for fluidizing the toner is supplied to the hopper 102a, the air pump 104, the screw pump 103, and the developing device 102 for supplying the toner to the developing device 102 by the air-fuel mixture conveying means 105. Since a circulation path for circulating toner in the order of the hopper 102a for replenishing toner is formed, the stator 103a made of rubber material of the screw pump 103 and the rotor 103b are brought into contact with each other due to abrasion with time. A gap is likely to be formed between the rotor 103a and the rotor 103b, air gradually leaks and flows out from the outside air, the ability to transfer toner from the outlet 103d of the screw pump 103 is reduced, and toner is supplied to the hopper 102a. Has been performed and the image quality has deteriorated (see FIG. 5).
[0003]
[Problems to be solved by the invention]
In the conventional image forming apparatus described above, air for fluidizing the toner is circulated by the air-fuel mixture conveying means. At this time, the air sucked by the air pump from the hopper for supplying the toner to the developing device is supplied to the screw pump. As a result, an air-fuel mixture with the toner is formed, and a circulation path for circulating the air-fuel mixture in the order of the hopper is formed. Since the hopper, the air pump, the screw pump, and the hopper for supplying the toner to the developing device are communicated in this manner, a gap between the stator and the rotor is likely to be generated due to abrasion of the stator and the rotor constituting the screw pump with time. When the air gradually leaks and flows out from the outside air and the ability to transfer toner from the outlet of the screw pump is reduced, toner supply to the hopper that supplies toner to the developing unit is not performed, and image quality is reduced. There was a problem of dropping.
Therefore, an object of the present invention is to solve such a problem. That is, due to the wear over time between the stator and the rotor constituting the screw pump, it is difficult to form a gap between the two, or even if a gap is formed, air leakage to the outside is prevented, and from the outlet of the screw pump, It is an object of the present invention to provide an image forming apparatus capable of forming a high-quality image without reducing the toner transfer ability.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, the present invention of claim 1 provides: Picture An image carrier; Picture The electrostatic latent image formed on the image carrier is Visualize with toner Developing means; A transfer unit for transferring a visible image on the image carrier onto transfer paper, and discharging toner collected from at least one of the image carrier and the transfer unit toward the developing unit Screw pump and the above screw pump The toner discharged from the outlet is sucked, the gas is supplied to the toner, and the toner is fluidized and then discharged, so that the toner is transported to the developing unit by the transporting force of the gas. An air pump, The screw pump, the air pump, the developing means, and the screw pump are communicated in this order to form a circulation path for a mixture of toner and gas. Mixture transport Route And The air pump is disposed in the middle of a mixed gas transport path communicating between the outlet of the screw pump and the developing means, so that the toner discharged from the screw pump is sucked and is directed in one direction toward the developing means. Image forming device that transports only Is the most important feature.
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the developing means is an image forming apparatus having a hopper for replenishing toner transported by a screw pump separately from gas. I do.
According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, it is a main feature that the image forming apparatus has a backflow prevention unit for preventing a backflow of the toner to the air pump.
According to a fourth aspect of the present invention, there is provided the image forming apparatus according to the third aspect, wherein the backflow prevention unit is provided with a backflow prevention member in an air-fuel mixture conveying unit coupled to a discharge port side of the air pump. It is the main feature.
According to a fifth aspect of the present invention, in the image forming apparatus according to the third aspect, the backflow prevention means is an image forming apparatus in which an air pump is disposed vertically above the hopper of the developing means. .
[0005]
[Action]
In the image forming apparatus configured as described above, Picture An image carrier; Picture The electrostatic latent image formed on the image carrier is Visualize with toner Developing means; A transfer unit for transferring a visible image on the image carrier onto transfer paper, and discharging toner collected from at least one of the image carrier and the transfer unit toward the developing unit Screw pump and the above screw pump The toner discharged from the outlet is sucked, the gas is supplied to the toner, and the toner is fluidized and then discharged, so that the toner is transported to the developing unit by the transporting force of the gas. An air pump, The screw pump, the air pump, the developing means, and the screw pump are communicated in this order to form a circulation path for a mixture of toner and gas. Mixture transport Route And The air pump is disposed in the middle of a mixed gas transport path communicating between the outlet of the screw pump and the developing means, so that the toner discharged from the screw pump is sucked and is directed in one direction toward the developing means. Only transported, A gap between the stator and the rotor due to abrasion with time between the stator and the rotor of the screw pump is less likely to occur or even if a gap is created, preventing air leakage to the outside air and preventing the air from leaking from the outlet of the screw pump. It is possible to provide an image forming apparatus capable of forming a high-quality image without reducing the toner transfer ability.
The developing means according to claim 2, further comprising: a hopper for supplying toner separated by gas from a screw pump to be supplied by a screw pump for visualizing an electrostatic latent image formed on an image carrier in an electrophotographic system to form a toner image. Is connected to an inlet and an outlet of an air pump for transferring a mixture of a toner and a gas for fluidizing the toner transferred by a screw pump, and conveys the mixture of the toner and the gas to a hopper of a developing unit. The hopper of the developing means, the screw pump, the air pump, and the hopper of the developing means so as to form a circulation path for circulating the gas in the order of the hopper of the developing means, the screw pump, the air pump, and the hopper of the developing means. Between the stator and the rotor due to wear over time between the stator and the rotor of the screw pump. It is difficult to create a gap or even if a gap is created, preventing air leakage to the outside air, separating toner and gas with a simpler structure without reducing the ability to transfer toner from the outlet of the screw pump It is possible to provide an image forming apparatus that performs high-quality image formation while preventing toner scattering or the like.
4. A developing means according to claim 3, further comprising: a hopper for separating the toner transported from the gas by a screw pump for visualizing an electrostatic latent image formed on an image carrier in an electrophotographic system to form a toner image and for supplying the toner. Is connected to an inlet and an outlet of an air pump for transferring a mixture of a toner and a gas for fluidizing the toner transferred by a screw pump, and conveys the mixture of the toner and the gas to a hopper of a developing unit. The hopper of the developing means, the screw pump, the air pump, and the hopper of the developing means so as to form a circulation path for circulating the gas in the order of the hopper of the developing means, the screw pump, the air pump, and the hopper of the developing means. And the backflow prevention means to prevent the backflow of toner to the air pump. A gap between the stator and the rotor due to abrasion with time between the stator and the rotor of the pump is less likely to occur, or even if a gap is formed, air leakage to outside air is prevented, and toner from the outlet of the screw pump is prevented. It is possible to provide an image forming apparatus in which the operation of the air pump is performed more reliably without lowering the transfer capacity of the image forming apparatus and a high quality image is formed.
5. A developing device according to claim 4, further comprising a hopper for supplying a toner separated from gas by a screw pump, which is supplied by a screw pump for visualizing an electrostatic latent image formed on an image carrier in an electrophotographic system to form a toner image. Is connected to an inlet and an outlet of an air pump for transferring a mixture of a toner and a gas for fluidizing the toner transferred by a screw pump, and conveys the mixture of the toner and the gas to a hopper of a developing unit. The hopper of the developing means, the screw pump, the air pump, and the hopper of the developing means so as to form a circulation path for circulating the gas in the order of the hopper of the developing means, the screw pump, the air pump, and the hopper of the developing means. And a backflow prevention member is disposed in the air-fuel mixture conveying means coupled to the discharge port side of the air pump. By providing a preventive means, it is difficult to form a gap between the stator and the rotor due to abrasion with time between the stator and the rotor of the screw pump, or even if a gap is formed, air leakage to the outside air is prevented. Therefore, it is possible to provide an image forming apparatus in which the operation of the air pump is reliably performed with a simpler structure without lowering the transfer capability of the toner from the outlet of the screw pump, and a high-quality image is formed. To
6. A developing device according to claim 5, further comprising a hopper for supplying toner separated from gas by a screw pump which is formed by a screw pump for visualizing an electrostatic latent image formed on an image carrier in an electrophotographic system to form a toner image. Is connected to an inlet and an outlet of an air pump for transferring a mixture of a toner and a gas for fluidizing the toner transferred by a screw pump, and conveys the mixture of the toner and the gas to a hopper of a developing unit. The hopper of the developing means, the screw pump, the air pump, and the hopper of the developing means so as to form a circulation path for circulating the gas in the order of the hopper of the developing means, the screw pump, the air pump, and the hopper of the developing means. And a backflow prevention means in which an air pump is arranged vertically above the hopper of the developing means. In this way, the gap between the stator and the rotor due to wear over time between the stator and the rotor of the screw pump is less likely to occur or even if a gap occurs, preventing air leakage to the outside air, It is possible to provide an image forming apparatus in which the operation of an air pump is reliably performed and a high-quality image is formed without reducing the ability to transfer toner from an outlet of a pump and without adding new components. Make it possible.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram mainly showing an image forming section and a toner recycling mechanism of the image forming apparatus of the present invention, and FIG. 2 is a cross-sectional view of an example of an air pump. In FIG. 1, an image carrier 1 of a drum-shaped photoreceptor is rotatably supported by a side plate (not shown), and is driven to rotate clockwise in a direction indicated by an arrow A by a driving means (not shown). The image carrier 1 is uniformly charged by a charger 10 by an image forming process in an electrophotographic system, and is then exposed according to a light image emitted from an exposure unit 11 to form an electrostatic latent image. It is formed. This latent image is developed by the developing means 2 to become a toner image, and the image carrier 1 carries the toner image.
The drum-shaped photoconductor of the image carrier 1 may be an endless belt-shaped photoconductor.
Further, although not shown, the exposing means 11 uses a copier of an analog optical system or a laser scanning optical system having a laser light source and a deflector to emit light onto the image carrier 1 in accordance with an image signal. If the writing method is adopted, the configuration becomes a laser printer, and if a document reading device is further provided, the configuration becomes a digital copying machine or a facsimile device. The developing unit 2 includes a developing roller 2b that supplies toner (T) to the electrostatic latent image formed and carried on the image carrier 1, a paddle 2c that agitates and transports the toner (T), and a paddle 2d. , A blade 2 e for regulating the height of the toner (T) layer, and a container 2 f for accommodating and holding the same, and a screw-fuel pump 3 and an air pump 4 for air-fuel mixture conveying means. (Air-fuel mixture transport route) By being conveyed in the elastic tube of No. 5, recycled or new toner (T) to be reused in the container 2f is supplied. Accordingly, new toner (Tn) provided separately from the developing means 2 and appropriately replenished to a developer storing means (not shown) is also stored in the container 2f by the screw pump 3 (not shown) and the air pump 4 (not shown). Will be replenished.
[0007]
The electrostatic latent image formed and carried on the image carrier 1 can be developed by a dry one-component or dry two-component development method using a magnetic brush development method with the toner (T) supplied from the developing means 2. It is visualized. The toner (T) in the container 2f of the developing means 2 is transported while being stirred by the paddles 2c and 2d, and the toner (T) and the carrier rub against each other, so that the toner adheres to the carrier. Then, the toner (T) forms a magnetic brush on the developing roller 2 b containing a magnet (not shown) and is developed with the toner (T) conveyed onto the image carrier 1.
The paper supply section 12 is provided with a plurality of paper supply cassettes containing transfer papers (P) of various sizes.
When the image forming operation is started, the image carrier 1 is charged by the charger 10, and the original image from the exposure unit 11 is exposed to form an electrostatic latent image. This electrostatic latent image is developed by a dry one-component developer of the developing means 2 or a dry two-component toner (T), and a toner image is formed on the image carrier 1. The transfer paper (P) is fed from the paper supply unit 12 to the toner image on the image carrier 1, and is supplied to a transfer position of a nip portion between the image carrier 1 and the transfer unit 14 via a registration roller 13. The image is transferred to the transfer paper (P). The transfer paper (P) onto which the toner image has been transferred is conveyed from the transfer means 14 to the fixing unit 15, where the toner image is fixed on the transfer paper (P) by the fixing unit 15, and the transfer paper (P) after fixing is fixed. Is discharged through a discharge roller 16 and stored in a discharge tray or the like.
[0008]
On the other hand, the residual toner adhered to the image carrier 1 or the toner (T) adhered to the transfer belt 14a after the transfer of the toner image is scraped off by the cleaning blade 7a of the cleaning unit 7 or the transfer cleaning blade 14b. Are discharged from the discharge pipe 7b or the discharge pipe 14c. The discharged collected toner (T) is conveyed to the screw pump 3 via the connecting means 8 and mixed with air supplied to the screw pump 3 by the air pump 4 to form an air-fuel mixture. The toner is conveyed in the toner conveying direction in the direction indicated by arrow B in the elastic tube of the air-fuel mixture conveying means 5, and is supplied to the container 2f of the developing means 2. The screw pump 3 is provided with a new toner (Tn) appropriately supplied to a toner storage unit (not shown) provided separately from the developing unit 2 or a collected toner (Tn) supplied through the discharge pipe 7b or the like. ) Is rotated by a motor of a drive source 9 and a pulley and a belt of a rotational driving force transmitting means 9a via a horizontal transport screw 8b in a horizontal transport screw case 8a to move the rotor 3b in the axial direction; A stator 3a having a passage arranged so as to enclose the stator 3b, and a holder 3c for holding and fixing the stator 3a in contact with the rotor 3b on the inner wall of the passage.
[0009]
In the air pump 4, as shown in FIG. 2, a suction valve 4c is held so as to be swingable in the direction of arrow C shown in FIG. 2 while facing the suction port 4a, and a discharge valve 4d is shown in FIG. The diaphragm 4f is moved in the direction indicated by the arrow E or in the direction opposite to the direction indicated by the arrow E by rotation of the eccentric cam 4e which is held swingably in the direction D and supported in the hole 4e '. When inhaling a mixture of the toner (T) and gaseous air, for example, when the diaphragm 4f is operated in the E direction, the suction valve 4c opens the suction port 4a and the discharge valve 4d switches the discharge port 4b. Close. Conversely, when discharging the mixture of the toner (T) and the gaseous air, the diaphragm 4f deforms and moves in the opposite direction to E, so that the suction valve 4c closes the suction port 4a and the discharge valve 4d opens the outlet 4b. For this reason, the mixture of the toner (T) and the gas air for fluidizing the toner (T) is transferred, and the gas air for fluidizing the toner (T) is circulated for reuse. (See FIG. 2).
In addition, what was illustrated as a mechanism for deforming the diaphragm 4f is merely an example, and is not limited to this.
The air pump 4 shown in FIG. 1 and the air pump 4 shown in FIG. 2 are different in the connection direction of the air-fuel mixture transport means 5, but any connection method is within the scope of the present invention. Included.
[0010]
The mixture of the toner (T) transferred by the screw pump 3 and the gas air circulated and supplied by the air pump 4 for fluidizing the toner (T) is elastically mixed with the mixture transfer means 5. The toner is conveyed through the tube in the toner conveying direction indicated by the arrow B, and is conveyed to a hopper 2a that supplies toner to the container 2f of the developing unit 2.
The hopper 2a drops the toner (T) of the air-fuel mixture that has been conveyed through the elastic pipe of the air-fuel mixture conveying means 5 and discharged inside by gravity, is separated from gaseous air, and is supplied to the container 2f as appropriate. .
The backflow prevention means 6 simply provides a valve 6b as a backflow prevention member 6a in the elastic pipe of the air-fuel mixture conveying means 5 connected to the discharge port 4b side of the air pump 4 so as to be openable and closable in the direction of arrow F shown in the figure. Thus, the toner (T) flowing backward when the air pump 4 is stopped or the like is blocked by the valve 6b of the backflow prevention member 6a.
The gaseous air separated from the toner (T) in the hopper 2a is supplied to the screw pump 3 through a circulation path that forms a circulation path by the air pump 4 that is connected to the air-fuel mixture conveying means 5. Have been reused.
[0011]
Therefore, the gas air reused by the screw pump 3 is circulated and supplied in the order of the air pump 4, the hopper 2a of the developing means 2, the screw pump 3, and the air pump 4. A gap between the stator 3a and the rotor 3b of the screw pump 3 due to abrasion with time of the stator 3a and the rotor 3b hardly occurs, or even if a gap occurs, air leakage to outside air is prevented, and the screw 3 The toner (T) is reliably transported to the hopper 2a of the developing means 2 without reducing the ability to transport the toner (T) from the outlet 3d of the pump 3, and high quality image formation is performed. Image forming apparatus can be provided.
That is, conventionally, the air for fluidizing the toner is transported in the order of the hopper of the developing unit, the air pump, the screw pump, and the hopper of the developing unit. However, in the present invention, the hopper of the developing unit, the screw pump, and the air pump are used. → Since the developer is circulated and transported in the order of the hopper, even if an extra gap is formed between the stator and the rotor due to abrasion, it is possible to prevent a decrease in the transfer capacity due to air leakage. In other words, the air pump does not directly supply air to the screw pump, but is disposed in the air-fuel mixture conveying means located on the discharge side (downstream side) of the screw pump, and conveys the toner in the air-fuel mixture conveying means in a diffusion state. Therefore, even if the conveying force of the screw pump itself is slightly reduced due to wear and tear, the decrease in the conveying force can be compensated for by assisting the air pressure from the air pump located on the downstream side.
[0012]
FIG. 3 is a schematic structural explanatory view of a toner recycling mechanism according to another embodiment of the present invention. In FIG. 3, the backflow prevention means 6 connects the air pump 4 in a direction more vertical than the hopper 2 a of the developing means 2. Since it is arranged above, even when the operation of the air pump 4 is stopped or the like, the backflow of the toner (T) to the air pump 4 is prevented. In other words, the backflow prevention means 6 of this embodiment is capable of transporting the air pump 4 when the operation of the air pump is stopped by devising a piping method and arranging the air pump 4 at a position higher than the hopper 2a without adding extra parts. By preventing the toner staying in the means 5 from flowing back into the air pump, it is possible to prevent a problem such as blocking a passage.
Therefore, the backflow of the toner (T) to the air pump 4 side is more reliably prevented without adding any new parts or devices, and the air pump 4 functions normally to provide high quality images. It has become possible to provide an image forming apparatus in which formation is performed.
[0013]
【The invention's effect】
Since the present invention is configured as described above, according to the invention of claim 1, Picture An image carrier; Picture The electrostatic latent image formed on the image carrier is Visualize with toner Developing means; A transfer unit for transferring a visible image on the image carrier onto transfer paper, and discharging toner collected from at least one of the image carrier and the transfer unit toward the developing unit Screw pump and the above screw pump The toner discharged from the outlet is sucked, the gas is supplied to the toner, and the toner is fluidized and then discharged, so that the toner is transported to the developing unit by the transporting force of the gas. An air pump, The screw pump, the air pump, the developing means, and the screw pump are communicated in this order to form a circulation path for a mixture of toner and gas. Mixture transport Route And The air pump is disposed in the middle of a mixed gas transport path communicating between the outlet of the screw pump and the developing means, so that the toner discharged from the screw pump is sucked and is directed in one direction toward the developing means. Only transported, A gap between the stator and the rotor due to abrasion with time between the stator and the rotor of the screw pump is less likely to occur or even if a gap is created, preventing air leakage to the outside air and preventing the air from leaking from the outlet of the screw pump. An image forming apparatus capable of forming a high-quality image without reducing the toner transfer ability can be provided. In other words, the air for fluidizing the toner is conventionally transferred in the order of the hopper of the developing unit, the air pump, the screw pump, and the hopper of the developing unit. However, in the present invention, the hopper of the developing unit, the screw pump, the air pump, and the like. Since the developer is circulated and transported in the order of the hoppers, even if a gap is formed between the stator and the rotor, it is possible to prevent a decrease in transfer capability due to air leakage. In other words, the air pump does not supply air to the screw pump, but is arranged in the air-fuel mixture conveying means located on the discharge side (downstream side) of the screw pump, and conveys the toner in the air-fuel mixture conveying means in a diffusion state. With this configuration, even if the conveying force of the screw pump itself slightly decreases due to wear and tear, the decrease in the conveying force can be compensated for by assisting the air pressure from the air pump.
[0014]
According to the second aspect of the present invention, there is provided a hopper for separating a toner transported from a gas by a screw pump for forming a toner image by visualizing an electrostatic latent image formed on an image carrier in an electrophotographic system and supplying the toner. The developing means has a suction port and an outlet port of an air pump for transferring a mixture of the toner and the gas for fluidizing the toner transferred by the screw pump, and the mixture of the toner and the gas is supplied to the developing means. The air-fuel mixture conveying means to be conveyed to the hopper, the hopper of the developing means, the screw pump, the air pump, the hopper of the developing means so as to form a circulation path for circulating gas in the order of the hopper of the developing means, the developing means The hopper of the means is connected to the stator and the rotor due to wear over time between the stator and the rotor of the screw pump. It is difficult to create a gap between the toner and the gas, and even if a gap is created, air leakage to the outside air is prevented, and the toner and the gas have a simpler structure without reducing the ability to transfer the toner from the outlet of the screw pump. And an image forming apparatus capable of preventing toner scattering or the like and forming a high quality image can be provided.
According to the third aspect of the present invention, there is provided a hopper which separates and supplies toner transferred by a screw pump which visualizes an electrostatic latent image formed on an image carrier in an electrophotographic system to form a toner image. The developing means has a suction port and an outlet port of an air pump for transferring a mixture of the toner and the gas for fluidizing the toner transferred by the screw pump, and the mixture of the toner and the gas is supplied to the developing means. The air-fuel mixture conveying means to be conveyed to the hopper, the hopper of the developing means, the screw pump, the air pump, the hopper of the developing means so as to form a circulation path for circulating gas in the order of the hopper of the developing means, the developing means The hopper is connected to the hopper and the backflow prevention means prevents the toner from flowing back to the air pump. A gap between the stator and the rotor due to abrasion with time between the stator and the rotor of the screw pump is less likely to occur, or even if a gap is formed, air leakage to the outside air is prevented, and the screw from the outlet of the screw pump is prevented. It is possible to provide an image forming apparatus in which the operation of the air pump is performed more reliably without reducing the toner transfer capability, and a high-quality image is formed.
[0015]
According to the fourth aspect of the present invention, there is provided a hopper that separates and supplies toner transported by a screw pump that visualizes an electrostatic latent image formed on an image carrier in an electrophotographic system and forms a toner image by supplying the toner with a gas. The developing means has a suction port and an outlet port of an air pump for transferring a mixture of the toner and the gas for fluidizing the toner transferred by the screw pump, and the mixture of the toner and the gas is supplied to the developing means. The air-fuel mixture conveying means to be conveyed to the hopper, the hopper of the developing means, the screw pump, the air pump, the hopper of the developing means so as to form a circulation path for circulating gas in the order of the hopper of the developing means, the developing means Means for communicating with the hopper of the means, and a backflow prevention member is arranged in the air-fuel mixture conveying means coupled to the discharge port side of the air pump. Since the backflow prevention means is provided, a gap between the stator and the rotor due to abrasion with time between the stator and the rotor of the screw pump is less likely to be generated or even if a gap is generated, air leakage to the outside air is prevented. Accordingly, it is possible to provide an image forming apparatus in which the operation of the air pump is reliably performed with a simpler structure without lowering the ability to transfer the toner from the outlet of the screw pump and high quality image formation is performed. I can do it.
According to the fifth aspect of the present invention, a screw hopper that visualizes an electrostatic latent image formed on an image carrier in an electrophotographic system to form a toner image separates and supplies toner transferred by a screw pump with a gas. The developing means has a suction port and an outlet port of an air pump for transferring a mixture of the toner and the gas for fluidizing the toner transferred by the screw pump, and the mixture of the toner and the gas is supplied to the developing means. The air-fuel mixture conveying means to be conveyed to the hopper, the hopper of the developing means, the screw pump, the air pump, the hopper of the developing means so as to form a circulation path for circulating gas in the order of the hopper of the developing means, the developing means Backflow preventing means which communicates with the hopper of the means and has an air pump disposed vertically above the hopper of the developing means Because it was provided, it is difficult to produce a gap between the stator and the rotor due to wear over time between the stator and the rotor of the screw pump, or even if a gap occurs, preventing air leakage to the outside air, Provided is an image forming apparatus in which the operation of the air pump is reliably performed and a high quality image is formed without reducing the transfer ability of the toner from the outlet of the screw pump and without adding new parts and devices. Now you can do it.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram illustrating an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is an enlarged explanatory diagram illustrating a main part of the image forming apparatus according to the exemplary embodiment of the present invention.
FIG. 3 is an explanatory diagram illustrating an image forming apparatus according to another embodiment of the present invention.
FIG. 4 is a development explanatory view for explaining a main part of a conventional image forming apparatus.
FIG. 5 is a cross-sectional view illustrating another main part of a conventional image forming apparatus.
[Explanation of symbols]
1 Image carrier
2 developing means, 2a hopper, 2b developing roller, 2c paddle,
2d padola, 2e blade, 2f container
3 screw pump, 3a stator, 3b rotor,
3c holder, 3d exit
4 air pump, 4a suction port, 4b discharge port, 4c suction valve,
4d discharge valve, 4e braided core cam, 4f diaphragm
5 mixture transport means,
6 Backflow prevention means, 6a Backflow prevention member
7 cleaning unit, 7a cleaning blade, 7b discharge pipe
8 connection means, 8a horizontal transport screw case, 8b horizontal transport screw
9 Driving source, 9a Rotary driving force transmission means
10 Charger
11 Exposure means
12 Paper feed unit
13 Registration roller
14 transfer means, 14a transfer belt, 14b transfer cleaning blade,
14c discharge pipe
15 Fixing unit
16 Paper ejection roller
101 Image carrier
102 developing unit, 102a hopper
103 screw pump, 103a stator, 103b rotor,
103c holder, 103d exit
104 air pump
105 Air-fuel mixture transport means
107 cleaning unit, 107a cleaning blade,
107b discharge pipe
108 connection means, 108a horizontal transport screw case,
108b Horizontal transport screw
109 drive motor, 109a rotational drive force transmission means

Claims (5)

And images bearing member, a developing means for visualizing with a toner an electrostatic latent image formed on images bearing member, a transfer unit that transfers the visible image on the image bearing member onto the transfer paper, at least the image bearing A screw pump that discharges the toner collected from either the body or the transfer means toward the developing means, and sucks the toner discharged from the outlet of the screw pump and supplies gas to the toner to fluidize the toner. An air pump that transports the toner to the developing means by the transport force of the gas by discharging the gas, and a circulation of an air-fuel mixture composed of the toner and the gas by communicating with the screw pump, the air pump, the developing means, and the screw pump in this order. And a mixture transport path forming a path ,
The air pump is disposed in the middle of a mixed gas transport path communicating between the outlet of the screw pump and the developing means, so that the toner discharged from the screw pump is sucked and is directed in one direction toward the developing means. An image forming apparatus characterized in that only an image is conveyed. 2. An image forming apparatus according to claim 1, wherein said developing means has a hopper for replenishing toner transported by a screw pump separately from gas. 3. The image forming apparatus according to claim 1, further comprising a backflow preventing unit configured to prevent a backflow of the toner to the air pump. 4. The image forming apparatus according to claim 3, wherein the backflow prevention unit has a structure in which a backflow prevention member is provided in a mixture transport path connected to a discharge port side of the air pump. 4. The image forming apparatus according to claim 3, wherein the backflow prevention unit has a configuration in which an air pump is disposed vertically above the hopper of the developing unit.

Images