JPH11237789A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device which prevents air from leaking out of a gap between the stator and rotor of a screw pump, and forms a high quality image without degradation in toner transfer capability. SOLUTION: The image forming device has an air pump 4 for circulating and supplying gas used for the flowing of toner which the screw pump 3 transfers to replenish a developing means 2 which forms a toner image by developing an electrostatic latent image formed on an image carrier 1. The device also has a gas-mixture carrying means 5 which carries the mixture of toner and gas by being connected to the suction port 4a and discharge port 4b of the air pump 4 for the passage of the mixture of toner and gas, and which allows the communication of the developing means 2, screw pump 3, air pump 4, and developing means 2 so that the gas circulates through the developing means 2, screw pump 3, air pump 4, and developing means 2 in that order.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to an electrostatic latent image formed on an image carrier in an electrophotographic system, in which toner transferred by a screw pump is mixed with gas to form 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 that supplies an image from a position distant from the printer.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus such as a printer, a facsimile apparatus, a copying machine, or a multifunction machine using a dry one-component or two-component dry toner,
Once the toner that has not been transferred onto the transfer body while being transferred onto the photoreceptor is collected by the cleaning unit,
Image formation is performed by recycling development that is returned to the developing device and reused. It is known that toner of a developer is circulated and supplied to a developing section by using a pump in a flow of gas (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 cross-sectional view showing a configuration around a screw pump. In the same 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. If you do
The collected toner discharged from the discharge pipe 107b of the cleaning unit 107 is dropped into the horizontal transport screw case 108a via the connection means 108, and the drive motor 10
9 is transmitted to the horizontal transport screw 108b in the horizontal transport screw case 108a via the pulley and the belt of the rotary drive power transmitting means 109a, and the stator 103 held by the holder 103c of the screw pump 103 is transmitted.
The collected toner is fed into the stator 103a by rotating integrally with the rotor 103b in the stator 103a. Rotor 103b in stator 103a constituting screw pump 103
The toner from the stator 103a to the outlet 1
The air is fed into the air-fuel mixture conveying means 105 connected to the outlet 103d so as to be extruded through the outlet 103d, and the air to be collected and circulated from the developing device 102 and used by the air pump 104 through the air transfer pipe 104a into the screw pump 103. The air pump 104 sucks the air sucked by the air pump 104 from the hopper 102a of the developing device 102 by feeding the air to the hopper 102a of the developing device 102 as a mixture with the air. Preventing toner scattering due to depressurization of the hopper 102a of the developing device 102, forming a circulation path with almost no air loss by using the screw pump 103, and transferring the toner to the developing device 102 from a position away from the developing position Is the image forming apparatus that supplies and forms an image an inventor of the same applicant? It has been proposed. However, in the conventional image forming apparatus, the air for fluidizing the toner is supplied to the developing unit 102 by the air-fuel mixture conveying means 105, the hopper 102a, the air pump 104, and the like.
Since the screw pump 103 and the hopper 102a for supplying toner to the developing unit 102 circulate in this order, a contact between the stator 103a made of rubber material of the screw pump 103 and the rotor 103b is made. Due to the abrasion over time, a gap is easily formed between the stator 103a and the rotor 103b, and air gradually leaks and flows out from the outside air, and the screw pump 10
3, the toner transfer ability from the outlet 103d is reduced,
There has been a problem that the toner is not supplied to the hopper 102a and the image quality is deteriorated (see FIG. 5).

[0003]

In the above-mentioned conventional image forming apparatus, air for fluidizing toner is circulated by a mixture-feeding means. At this time, an air pump is supplied from a hopper for supplying toner to a developing device. Supplies the sucked air to the screw pump to form a mixture with the toner, and forms a circulation path for circulating the mixture in the order of the hopper. Since the hopper, the air pump, the screw pump, and the hopper for supplying the toner to the developing device are communicated as described above, a gap between the stator and the rotor is easily generated due to the wear 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 decreases, 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 that constitute 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]

According to a first aspect of the present invention, there is provided an electrophotographic system in which toner transferred by a screw pump is transferred to an electrostatic latent image formed on an image carrier in an electrophotographic system. An image forming apparatus that forms an image by supplying an air-fuel mixture from a position distant from the developing position and an image carrier that carries the formed image, and an electrostatic latent image formed on the image carrier is visualized. Developing means for forming a toner image by forming a toner image, a screw pump for transferring toner to be supplied to the developing means, an air pump for circulating and supplying gas for fluidizing the toner transferred by the screw pump, and The air pump is connected to a suction port and a discharge port through which the mixture of the toner and the gas passes, and conveys the mixture of the toner and the gas. An image forming apparatus having the developing unit, the screw pump, the air pump, and a mixture transporting unit communicating with the developing unit so as to form a circulation path for circulating the air pump and the developing unit in this order. 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 unit is an image forming apparatus having a hopper for replenishing toner transported by a screw pump by separating the toner from gas. I do. A third aspect of the present invention is the image forming apparatus according to the first or second aspect, characterized in 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 transporting 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 of 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]

According to the first aspect of the present invention, there is provided an image forming apparatus comprising: a developing unit configured to visualize an electrostatic latent image formed on an image carrier in an electrophotographic system to form a toner image; An air / fuel mixture which is coupled to an inlet and an outlet of an air pump for transporting an air / gas mixture for fluidizing the toner transported by the screw pump and transports the air / gas mixture to the developing means. Means for developing,
A screw pump, an air pump, and a developing unit so as to form a circulation path for circulating gas in the order of the developing unit, the screw pump, the air pump, and the developing unit are communicated with each other, between the stator and the rotor of the screw pump. A gap between the stator and the rotor due to abrasion with time is less likely to occur, or even if a gap is formed, air leakage to the outside air is prevented, and the transfer capability of the toner from the outlet of the screw pump is reduced without a decrease. An image forming apparatus capable of forming a high quality image can be provided. The developing means according to claim 2, further comprising a hopper for supplying toner separated by gas from a screw pump which is transferred 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 form a gap or even if a gap occurs, 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 in which high quality image formation is performed while preventing toner scattering or the like. 4. A developing device according to claim 3, further comprising a hopper for separating the toner transported from the gas by a screw pump for replenishing the toner transported 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. A mixture transporting means, a hopper of a developing means, a screw pump,
The hopper of the developing means, the screw pump, the air pump, and the hopper of the developing means are communicated with each other so as to form a circulation path for circulating the gas in the order of the air pump and the hopper of the developing means. To prevent the toner from flowing backward, so that a gap between the stator and the rotor due to abrasion with time between the stator and the rotor of the screw pump hardly occurs, or even if a gap is formed, air leakage to the outside air is prevented. To provide an image forming apparatus in which the operation of the air pump is more reliably performed without reducing the transfer capability of the toner from the outlet of the screw pump, and a high-quality image is formed. I do. 5. A developing device according to claim 4, further comprising: a hopper that separates a toner transported from a 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 replenishes 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 air-fuel mixture conveying means, the hopper of the developing means, a screw pump, an air pump, the hopper of the developing means, a screw pump, so as to form a circulation path for circulating gas in the order of the hopper of the developing means,
The air pump and the hopper of the developing means are communicated with each other, and the back flow preventing means in which the back flow preventing member is provided in the air-fuel mixture conveying means coupled to the discharge port side of the air pump is provided. A gap between the stator and the rotor due to wear over time between the rotor and the rotor is less likely to occur, or even if a gap is created, prevents air leakage to the outside air and transfers toner from the outlet of the screw pump. 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 and the high-quality image formation is performed without reduction. 6. A developing means having a hopper for separating a toner transported from a gas by a screw pump for replenishing toner transported 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 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. Hopper of the developing means,
The screw pump, the air pump, and the hopper of the developing unit are connected to the hopper of the developing unit, the screw pump, the air pump, and the hopper of the developing unit so as to form a circulation path for circulating the gas in order, and the air pump is developed. By providing a backflow prevention means arranged vertically above the hopper of the means, 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 a gap is formed. Even if it occurs, air leakage to the outside air is prevented, the operation of the air pump is reliably performed without reducing the ability to transfer toner from the outlet of the screw pump, and without adding any new parts. An image forming apparatus capable of forming a high quality image can be provided.

[0006]

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, a drum-shaped photosensitive member image carrier 1 is shown.
Is rotatably supported by a side plate (not shown), and is driven to rotate clockwise in the direction of arrow A shown in the figure by driving means (not shown). The image bearing member 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 an analog optical copying machine or a laser scanning optical system having a laser light source and a deflector to light the image carrier 1 on 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 installed, the configuration becomes a digital copying machine or a facsimile machine. The developing unit 2 includes a developing roller 2 that supplies a toner (T) to the electrostatic latent image formed and carried on the image carrier 1.
b, paddles 2c and 2d for stirring and transporting the toner (T), and a blade 2 for regulating the height of the toner (T) layer
e, and a container 2f for accommodating and holding them, and the screw pump 3 and the air pump 4 convey the gas through the elastic pipe of the air-fuel mixture conveying means 5 so as to be recycled in the container 2f. Alternatively, new toner (T) is supplied. Therefore, 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.

The electrostatic latent image formed and carried on the image carrier 1 is developed by a magnetic brush developing method using a dry one-component or dry two-component developing system using the toner (T) supplied from the developing means 2. The image is visualized by the method. The toner (T) in the container 2f of the developing means 2 is
c, the toner (T) and the carrier are rubbed while being stirred by the paddle 2d, and 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 feed unit 12 is provided with a plurality of paper feed cassettes containing transfer papers (P) of various sizes. When the image forming operation is started, the image carrier 1 is moved to the charger 10.
, And the document image from the exposure means 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. Transfer paper (P) is fed from the paper feed 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) on 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 transferred. Is discharged via a discharge roller 16 and stored in a discharge tray or the like.

On the other hand, the image carrier 1 after transfer of the toner image
The residual toner adhering to the top or the toner (T) adhering to the transfer belt 14a is removed by the cleaning blade 7a of the cleaning unit 7 or the transfer cleaning blade 14b.
And is 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 connection means 8 and mixed with air supplied from the air pump 4 to the screw pump 3 to form an air-fuel mixture. The toner is conveyed in the toner conveying direction indicated by arrow B in FIG.
It is designed to be replenished within f. The screw pump 3 is provided with a new toner (T) that is appropriately supplied to a toner storage unit (not shown) provided separately from the developing unit 2.
n) Alternatively, the collected toner (T) supplied by the discharge pipe 7b or the like is fed to the horizontal conveying screw case 8a via the motor of the driving source 9 and the pulley and belt of the rotational driving force transmitting means 9a. A rotor 3b that rotates via a transport screw 8b and moves in the axial direction, and a stator 3a having a passage arranged so as to surround the rotor 3b.
A holder 3c for holding and fixing the stator 3a in contact with the rotor 3b on the inner wall of the passage.

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 a suction port 4a, and a discharge valve 4d is opposed to a discharge port 4b.
Is held so as to be swingable in the direction of arrow D shown in FIG.
The diaphragm 4f moves in the illustrated arrow E direction or the opposite direction of the illustrated arrow E direction by rotation of the eccentric cam 4e supported therein. When the mixture of the toner (T) and the gaseous air is to be sucked, the suction valve 4c opens the suction port 4a and the discharge valve 4d opens the discharge port 4b by, for example, operating the diaphragm 4f in the E direction. Close. Conversely, when discharging a mixture of toner (T) and 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. Note that the air pump 4 shown in FIG. 1 and the air pump 4 shown in FIG. 2 have different connection directions of the air-fuel mixture transporting means 5, but any connection method is within the scope of the present invention. Included.

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 supplied to the mixture transfer means. 5 is conveyed in the toner conveying direction indicated by arrow B in FIG.
Is transported to a hopper 2a that supplies toner to the container 2f. 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 therein 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 coupled 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. so,
Toner (T) flowing backward when the air pump 4 stops
Is prevented 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 communicated with the mixture transport means 5. Have been reused.

Accordingly, 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. Therefore, the stator 3a of the screw pump 3 and the rotor 3
b, the gap between the stator 3a and the rotor 3b is hardly generated or even if the gap is formed, air leakage to the outside air is prevented, and the toner (T) from the outlet 3d of the screw pump 3 is prevented. 2), it is possible to provide an image forming apparatus in which the toner (T) is reliably conveyed to the hopper 2a of the developing unit 2 to form a high-quality image without reducing the transfer capability of the developing unit 2. Became. 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 arranged in the air-fuel mixture transport means located on the discharge side (downstream side) of the screw pump, and transports the toner in the air-fuel mixture transport 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.

FIG. 3 is a schematic diagram illustrating the structure 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 to the hopper 2 a of the developing means 2. Are also arranged vertically upward, so that 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 can be configured such that the air pump 4 is arranged at a position higher than the hopper 2a by devising a piping method without adding extra parts, thereby conveying when the operation of the air pump is stopped. It is possible to prevent the toner remaining in the means 5 from flowing back into the air pump, thereby preventing problems such as blocking a passage. Therefore, the backflow of the toner (T) to the air pump 4 side is more reliably prevented without adding new parts and devices, and the air pump 4 functions normally to provide high quality images. An image forming apparatus in which formation is performed can be provided.

[0013]

According to the present invention, the electrostatic latent image formed on the image carrier in the electrophotographic system is visualized to form a toner. The developing means for forming an image is coupled to an inlet and an outlet of an air pump for transferring a mixture with a gas for fluidizing toner transferred by a screw pump,
A developing means, a screw pump, an air pump, and a gas mixture transporting means for transporting an air-fuel mixture of the toner and the gas to the developing means so as to form a circulation path for circulating the gas in order of the developing means, the screw pump, the air pump, and the developing means. pump,
Since the developing means is communicated with the developing means, 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. Thus, it is possible to provide an image forming apparatus capable of forming a high-quality image without reducing the ability to transfer the toner from the outlet of the screw pump. That is, 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 the transfer capability due to air leakage. In other words, the air pump does not 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. With this configuration, even if the transport force of the screw pump itself slightly decreases due to wear and tear, the decrease in the transport force can be compensated for by assisting the air pressure from the air pump.

According to the second aspect of the present invention, the toner transferred by the screw pump which forms the toner image by visualizing the electrostatic latent image formed on the image carrier in the electrophotographic system is separated from the gas and supplied. Developing means having a hopper
Mixing that is connected to the inlet and outlet of an air pump that transports a mixture of gas and a gas for fluidizing toner transported by a screw pump, and that transports the mixture of toner and gas to the hopper of the developing means. The air conveying means, a hopper of the developing means, a screw pump, an air pump, a hopper of the developing means, a screw pump, an air pump, and a 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. Since the communication is performed, 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. The toner and gas are separated by a simpler structure without reducing the transfer capacity of the toner from the outlet of the screw pump. Prevention to the high-quality image forming generation etc. has become possible to provide an image forming apparatus to be performed. 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 forms a toner image by visualizing an electrostatic latent image formed on an image carrier in an electrophotographic system. The developing means has a suction port and an exhaust port of an air pump for transferring a mixture of the toner and the gas for fluidizing the toner transferred by the screw pump. The air-fuel mixture conveying means for conveying to the hopper, the hopper of the developing means, a screw pump, an air pump, the hopper of the developing means so as to form a circulation path for circulating the gas in 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. Even if a gap is less likely to occur or gap between the stator and the rotor over time wear between the stator and the rotor of the clew pump,
Provided is an image forming apparatus in which air leakage to outside air is prevented, the operation of the air pump is performed more reliably without reducing the transfer capability of toner from the outlet of the screw pump, and high-quality image formation is performed. I can do it.

According to the fourth aspect of the present invention, the toner is transferred by a screw pump which forms a toner image by visualizing an electrostatic latent image formed on an image carrier in an electrophotographic system, and supplies the toner separated from gas. Developing means having a hopper
Mixing that is connected to the inlet and outlet of an air pump that transports a mixture of gas and a gas for fluidizing toner transported by a screw pump, and that transports the mixture of toner and gas to the hopper of the developing means. The air conveying means, a hopper of the developing means, a screw pump, an air pump, a hopper of the developing means, a screw pump, an air pump, and a 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. A backflow prevention means having a backflow prevention member disposed in the air-fuel mixture conveying means coupled to the discharge port side of the air pump is provided, so that the time between the stator and the rotor of the screw pump can be reduced. The gap between the stator and the rotor due to wear 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 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 a high-quality image is formed. Was. According to the fifth aspect of the present invention, there is provided a hopper for separating a toner transported from a 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 replenishing the toner. The developing means has a suction port and an exhaust port of an air pump for transferring a mixture of the toner and the gas for fluidizing the toner transferred by the screw pump. The air-fuel mixture conveying means for conveying to the hopper, the hopper of the developing means, a screw pump, an air pump, the hopper of the developing means so as to form a circulation path for circulating the gas in order of the hopper of the developing means, the developing means. Backflow prevention means which communicates with the hopper of the means and has an air pump disposed vertically above the hopper of the developing means Since it is provided, it is difficult to produce a gap between the stator and the rotor due to the wear over time between the stator and the rotor of the screw pump, or even if a gap is produced, preventing air leakage to the outside air, Provided is an image forming apparatus in which the operation of the air pump is performed reliably and high-quality image formation is performed without reducing the ability to transfer 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]

DESCRIPTION OF SYMBOLS 1 Image carrier 2 Developing means, 2a hopper, 2b developing roller, 2
c paddler, 2d paddler, 2e blade, 2f container 3 screw pump, 3a stator, 3b rotor, 3c holder, 3d outlet 4 air pump, 4a suction port, 4b discharge port, 4
c suction valve, 4d discharge valve, 4e braided cam, 4f diaphragm 5 air-fuel mixture conveying means, 6 backflow prevention means, 6a backflow prevention member 7 cleaning unit, 7a cleaning blade, 7b discharge pipe 8 connection means, 8a horizontal conveyance screw case , 8b
Horizontal conveyance screw 9 Drive 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 Discharge Roller 101 Image carrier 102 Developing device, 102a Hopper 103 Screw pump, 103a Stator, 10
3b rotor, 103c holder, 103d outlet 104 air pump 105 air-fuel mixture transport means 107 cleaning unit, 107a cleaning blade, 107b discharge pipe 108 connecting means, 108a horizontal transport screw case, 108b horizontal transport screw 109 drive motor, 109a rotational driving force transmission means

Claims (5)

[Claims] 1. An image forming an image by supplying 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 away from a developing position. In the forming apparatus, an image carrier for carrying a formed image, developing means for visualizing an electrostatic latent image formed on the image carrier to form a toner image, and toner to be supplied to the developing means are transferred. Screw pump, an air pump that circulates and supplies gas for fluidizing the toner transferred by the screw pump, and is connected to an inlet and an outlet of the air pump through which a mixture of toner and gas passes. Forming a circulation path for conveying the mixture of the toner and the gas and circulating the gas in the order of the developing unit, the screw pump, the air pump, and the developing unit. An image forming apparatus, comprising: the developing unit, the screw pump, the air pump, and a mixed-air conveying unit that communicates with the developing unit. 2. The image forming apparatus according to claim 1, wherein
An image forming apparatus, wherein the developing means includes 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 image forming apparatus according to claim 1, wherein the backflow prevention unit has a configuration in which a backflow prevention member is provided in a gas-mixture conveying unit coupled to a discharge port side of the air pump. 5. The image forming apparatus according to claim 3, wherein
The image forming apparatus is characterized in that the backflow prevention means has a configuration in which an air pump is disposed vertically above the hopper of the developing means.