JP2002287497A - Developer transporting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an abnormal image from being formed due to that aggregated toner caused by passing through a powder pump is transferred to paper by removing the aggregated toner caused by passing through the powder pump. SOLUTION: This developer transporting device for transporting developer to a developing device 200 by the powder pump 1 having a female screw type stator 2 provided with a double-pitch spiral groove inside and a male screw type rotor 3 rotatably inserted and fit in the stator is provided with a mesh member 30 for regulating the particle size of toner to be supplied to the developing device in the middle of a transport path from the powder pump to the developer replenishing port of the developing device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a developer transfer device used in an image forming apparatus such as an electrophotographic printer, a facsimile or a copying machine using a two-component developer or a one-component developer. New developer (toner)
The present invention relates to a developer transfer device that transports collected toner after transfer and transfer to a developing device or a waste toner container, and to an improvement in a screw pump used for the device.

[0002]

2. Description of the Related Art In an image forming section of an electrophotographic image forming apparatus, an electrostatic latent image formed on a photoreceptor is developed with a toner supplied from a developing device to form a toner image. Is transferred onto a transfer paper and fixed to form an image. When the amount of toner in the developing device decreases, the toner is supplied into the developing device by the toner replenishing means. As the toner replenishing means, a relatively small-capacity toner cartridge directly connected to the developing device is used, and a relatively large-capacity toner bottle is
It is often located at a position distant from the developing device from the layout of the device, particularly at a position lower than the developing device. In addition, a type is known in which a large amount of copy processing can be continuously performed by using a toner bank as a large-capacity toner storage means regardless of inside or outside the apparatus main body. Further, a charging device, a developing device, a transfer device, a cleaning device, and the like are sequentially arranged around the photosensitive drum along the rotation direction thereof. The cleaning device is a unit that removes toner remaining on the photoconductor after the toner image on the photoconductor drum is transferred onto the transfer paper by the transfer device, but recently, based on a request for toner recycling,
Various toner recycling systems have been proposed and implemented in which toner removed and collected by a cleaning device is resupplied to a developing device for reuse without being discarded.
In any of the above cases, since the developing device and the toner sending source are separated from each other, it is necessary to connect the feeding device and the developing device with a pipe or the like to transfer the toner.

[0003] As a conventional main method for transferring a developer and a toner, the following examples can be given. (1) A method in which a source and a destination are connected by a pipe, and developer and toner are transferred by a coil screw provided inside the pipe. This method is suitable for a linear conveyance path due to the nature of the coil screw, but has a drawback that it cannot be applied to a curved or bent path. (2) A method in which a sending source and a sending destination are arranged close to each other in a vertical position, and are dropped and transferred mainly by gravity. In this method, since the positional relationship between the sending source and the sending destination is limited to a specific range, there is a drawback that the degree of freedom of layout is low and the utility is poor. (3) A method in which a powder pump (uniaxial eccentric screw pump, commonly known as a Mohno pump) is used to transfer from a source arranged in a free positional relationship to a destination. This method is used as a means for replenishing new toner and developer, a means for recycling collected toner, and the like, and a flexible transfer tube can be used.
This has the advantage that the transfer route can be selected irrespective of obstacles in the transfer route. The powder pump enables the developer and toner to be transferred by a suction or discharge pressure generated by the rotation of the male screw rotor in the fixed rubber material female screw stator, but the rotor and the stator slide. For this reason, depending on certain conditions, the toner that has passed through the powder pump is rubbed and rarely aggregated, and when the toner aggregate is directly transferred to an image, there is a problem that an abnormal image is generated. . In particular, in a suction-type powder pump used for suction transfer of toner, a suction force is not generated and a conveying force cannot be obtained unless the rotor and the stator have high sealing properties, so that the amount of biting between the rotor and the stator is large. In many cases, the setting is made, so that the toner is more likely to aggregate. Further, when the use environment is high temperature and high humidity, or when the original fluidity of the toner to be used is poor, the toner is more likely to aggregate due to the transfer by the powder pump, and the above problem is likely to occur.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is intended for transferring a developer or a toner even when a powder pump is operated for a long time or when environmental conditions such as temperature and humidity are deteriorated. Provided is a developer transfer device capable of reliably preventing toner aggregates generated at the time from being transferred onto an image.

[0005]

In order to achieve the above-mentioned object, a first aspect of the present invention is to provide a female screw type stator having a double pitch spiral groove therein, and a male screw rotatably fitted in the stator. And a developer pump for transferring the developer to the developing device by a powder pump having a shape rotor. The developer is supplied to the developing device in a transfer path from the powder pump to the developer supply port of the developing device. A mesh member for regulating the particle size of the toner to be formed. According to a second aspect of the present invention, the powder pump is a suction screw pump provided near a developer supply port of the developing device, and the mesh member is provided near a discharge port of the suction screw pump. It is characterized by the following. According to a third aspect of the present invention, a cleaning member is attached to the drive shaft drive shaft for driving the suction type screw pump to rotate and to remove the developer abutting on and adhering to the mesh member when the drive shaft is driven to rotate. It is characterized. The invention according to claim 4, wherein the cleaning member is a thin plate member or an elastic member attached to a drive shaft of a suction screw pump,
Alternatively, it is a brush. The invention according to claim 5 is characterized in that the discharge case provided with the developer supply port is provided with a discharge port and a storage case for discharging and storing the residue remaining on the mesh member. The invention according to claim 6 is that the powder pump is a discharge screw pump provided at a position distant from the developing device, and the mesh member is provided near a discharge port of the discharge screw pump. It is characterized by. According to a seventh aspect of the present invention, there is provided an air supply means for blowing air to the mesh member to remove foreign matter remaining on the mesh member. The invention according to claim 8 is characterized in that a means for controlling the operation of the air supply means and a means for controlling the drive of the powder pump are separately provided, and the air supply means is operated when the powder pump is stopped. I do. According to a ninth aspect of the present invention, the air supply unit is separately provided with a unit for controlling the operation of the air supply unit and a unit for controlling the drive of the powder pump, and the air supply unit is operated immediately after stopping the operation of the powder pump. Features. The invention according to claim 10 is characterized in that the mesh member is provided in a plurality of stages.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the accompanying drawings. First, FIG. 1 is an exploded sectional view showing a configuration of a discharge type developer transfer device.
Note that the developer refers to a carrier or a toner, or a mixture of a carrier and a toner. Reference numeral 1 denotes a screw pump type powder pump, which is a female screw type stator 2 having a double-pitch spiral groove made of an elastic member such as rubber formed on an inner peripheral surface thereof, and rotatably fitted into the stator 2. And a male screw type rotor 3 made of metal, resin, or the like. This rotor 3 has a transfer screw 3 on the upstream side.
The shaft 10 is connected to the shaft 10 by a spring pin 12 or the like, and is driven to rotate by rotating the transfer screw 310. By rotating the rotor, a discharge pressure is generated at the discharge port 6. The periphery of the stator 2 is covered with a holder 4 fixed to a side plate, and a gap 5 is provided between an inner peripheral surface of the holder 4 and an outer peripheral surface of the stator 2. The gap 5 is communicated with a developer discharge port 6 on the downstream side of the rotor 3. The holder 4 is provided with an air supply port 7 communicating with the gap 5.
The air supply port 7 is fitted with an air supply tube 622 from the air pump 600 in FIG. Air pump 60
The air from 0 is supplied from the air supply port 7 to the discharge port 6 through the gap 5 to fluidize the developer, and smoothly and reliably discharge the developer in the direction of the arrow by the discharge pressure of the powder pump. 2 and 3 are views of a suction type toner supply device. Except that the transfer screw is not provided on the shaft 11 and that the holder 4 has no air supply port, it is the same as the discharge type of FIG. 1 and that the rotor 3 and the stator 2 are the same as the discharge type powder pump 1.
By rotating the shaft 11 in the opposite direction to that of the discharge type (or by using a rotor and a stator wound in reverse to the discharge type), a suction pressure is generated at the suction port 6, and the toner sucked from the suction port 6 is sucked. Spit in 11 directions. There is an idea that the suction pressure can be secured by increasing the amount of bite between the stator 2 and the rotor 3, but if the amount of bite is increased in a dark cloud, the torque increases, the temperature rises, and the powder passes through the powder pump. The toner is likely to aggregate. On the other hand, if the bite amount is reduced, the suction / conveyance force is reduced, but it tends to be better in terms of torque, temperature rise, and toner cohesion degree. By setting the bite amount in an appropriate range, the maximum suction pressure can be efficiently secured. Further, it is desirable to appropriately select the range of the bite amount in consideration of the toner to be used, the lift, the transfer distance, the required operation time, the use environment, and other conditions.

The suction type powder pump 1 shown in FIGS. 2 and 3
In the transfer device provided with
The nozzle 510 and the transfer tube 301, which are toner passages connecting the toner to the powder pump 1, and the transfer tube 301 are hermetically sealed.
1. The toner is transmitted to the toner 450 in the toner cartridge 400 via the nozzle 510, and the toner can be transferred. At this time, air is supplied to the toner in the toner cartridge 400 through the nozzle 510 by the air pump (air supply means) 600. After suctioning the toner 450 near the nozzle 510 by the powder pump 1, a bridging phenomenon (a cavity is formed in a portion of the lost toner) occurs in the cartridge, and the toner supply amount becomes unstable, However, by supplying air to the inside of the toner cartridge, the toner can be stirred and fluidized, and the above-described cross-linking phenomenon of the toner can be prevented. Alternatively, since the crosslinked toner can be broken by the supplied air, the toner supply amount can be stabilized and the remaining amount of toner in the container can be reduced. At this time, as shown in FIG. 3, the air permeable filter 4
It is also possible to provide 40, which serves to depressurize the inside of the cartridge from rising to a positive pressure due to the air supplied from the air pump 600 described above.

The sucked toner falls into a developing device through a toner introduction hole (developer supply port) 23 provided in a part of the developing container 200, and is supplied when a two-component developing system is used. The collected toner (aspirated toner) is stirred and mixed with the developer in the developing device 200 to have a uniform concentration of the agent and an appropriate charge amount. The transfer member 310 has a tube shape with an inner diameter of about 4 to 7 and is a flexible and highly toner-resistant rubber material (ex. Polyurethane, nitrile, EPDM,
It is very effective to use a silicon material or the like or a plastic material (polyethylene, nylon or the like). The container holder 500 holds the protective case 40 of the toner cartridge 400.
Hold 1 The protective case 401 is made of a rigid material such as paper, cardboard, or plastic, and has a structure in which the protective case 401 wraps around the bag-shaped toner storage member 410 and partially engages with the base member 420. The bag-shaped toner storage member 410 is
A flexible sheet made of resin or paper (thickness of about 80 to 200 μm) made of resin such as polyethylene or nylon is made into a single-layer or multi-layer structure, and is made like origami production. It is made in the shape of a bag. The base member 420 is made of a case 42 made of resin, paper, or the like.
1 and a seal 422 such as a sponge.
No. 0 has a toner discharge hole 512 at the tip and a toner discharge path 513 at the shaft core. When the toner cartridge 400 is set in the container holder, the nozzle 510 is inserted into the seal 422 of the base member, and the seal 422 is in close contact with the nozzle 510 to prevent toner leakage from the toner cartridge to the outside of the apparatus. The difference between the constitutions of the powder pumps of FIGS. 2 and 3 is that the air is not injected into the toner cartridge 400 by the air pump 600 (FIG. 2) or the air is injected (FIG. 3). FIG. 2 shows a toner replenishing device in which the volume of the cartridge is reduced as it is discharged from the toner cartridge 400, and the cartridge can be taken out in a completely crushed state after use.

Next, FIG. 4 shows an embodiment of an apparatus for conveying toner only by air. The same parts as those in the above embodiment are denoted by the same reference numerals and described. By supplying air from the air pump 600 to the cartridge 400 via the nozzle 510, the toner 450 in the cartridge is agitated, and at the same time, a force to discharge air and toner out of the cartridge due to a rise in pressure in the cartridge acts. .
This becomes the toner conveying force of the present apparatus, and the toner is conveyed to the inside of the developing device 200 via the joint 270 through the conveying tube 301 connected to the nozzle. At this time, if the transfer route and the developing device 200 that is the transfer destination are sealed or have low air permeability, the pressure inside the developing device 200 is increased by air supplied simultaneously with the toner, and the air is eventually supplied to the cartridge. Also, no toner is conveyed. For this purpose, the developing device 200 is provided with an air vent filter 251 to prevent the above-mentioned problem. FIG. 5 is an embodiment of the present invention corresponding to the view of the powder pump unit of the developer transfer device of FIG. 2 or FIG. FIG. 6 is a perspective sectional view of FIG. As shown in the drawing, a mesh member 30 is attached to a portion (developer supply port) 23 of the powder pump unit until toner discharged from the powder pump 1 is supplied into the developing device 200, and Of the toner discharged from the pump 1, only the aggregated toner can be removed. Generally, since the particle size of the toner is about 5 to 20 μm,
It is desirable to use a mesh member having a coarseness of about m. As described above, the mesh member 30 is attached to the inside of the developer supply port 23 inside the discharge case 20 so that all the toners are sorted by the mesh member 30, so that the aggregated toner and other foreign substances are removed from the developing device. It can be prevented from entering the side.

FIG. 7 shows a cleaning member 3 for preventing clogging of the mesh member 30 in the toner supply device of FIG.
2 is an embodiment in which the drive shaft 2 is attached to a drive shaft 11 of a rotor.
The cleaning member 32 having one end fixed to the drive shaft 11 is in sliding contact with the mesh member 30 when the drive shaft 11 rotates,
The material and dimensions are set so that the toner aggregate remaining on the mesh member 30 can be scraped off. Cleaning member 3
An excellent cleaning effect can be obtained at low cost by using a resin mylar such as polyethylene or polyurethane, or a sheet-like material made of an elastic member such as polyurethane rubber or chloroprene rubber. According to this embodiment, since the aggregated toner and the like accumulated on the mesh member 30 are removed by the cleaning member 32, when the aggregated toner and the like are captured by the filter function of the mesh member 30, the aggregated toner and the like are formed on the upper surface of the mesh member 30. Can be effectively prevented from accumulating and causing clogging. FIG.
7 is a modification of the embodiment of FIG. 5 similarly to FIG. 7, but is characterized in that the cleaning member 32 is a brush. In other words, the manufacturing member 32 made of a brush is implanted on the outer periphery of the drive shaft 11 so that the tip of the manufacturing member 32 can slide on the mesh member 30. 7, the bristle of the brush enters the mesh of the mesh member 30, and the aggregates clogged by the mesh member can be removed more effectively than the sheet-like elastic member of FIG.

FIGS. 9 (a), 9 (b) and 9 (c) are cross-sectional views of the discharge case 20 of the powder pump unit of FIG. An agglomerate storage case 35 is communicated with a side of the discharge case 20. When the cleaning member 32 is rotationally driven by the rotation of the drive shaft 11, the toner aggregates on the mesh member 30 are scraped off and stored in a newly provided aggregate storage case 35, as indicated by arrows. When the drive shaft 11 is rotated in the direction shown in FIG.
(A), (b) and (c), the toner aggregates TG are scraped off by the cleaning member 32 and eventually the cleaning member 3
2 passes through the outlet 34 and is discharged from the outlet 34 into the storage case 35. Therefore, the mesh member 30
It is possible to prevent foreign matters such as aggregated toner removed from above from remaining in the discharge case 20 and causing clogging. Figure 1
Reference numeral 0 denotes an embodiment in which a toner aggregate removing means is provided in a powder pump unit of a developer transfer device using the same discharge type powder pump as that shown in FIG. By attaching the mesh member 30 to the vicinity of the discharge outlet of the powder pump (downstream side) as shown in the holder 4 of the stator 2 of the powder pump 1, it is possible to remove the aggregated toner after passing through the powder pump. In the case of this embodiment, since the mesh member 30 is attached near the discharge port 6, clogging of the mesh member 30 is less likely to occur due to the vigorously discharged toner by the discharge pressure of the powder pump 1.
Further, the air pump 600 is connected to the air supply port 7, and the air supplied from the air pump 600 is blown into the case from the air supply port 7 to blow off the toner and aggregates attached to the mesh member 30. Can be.

FIGS. 11 (a), 11 (b) and 11 (c) show the discharge case 20 of the powder pump unit similarly to the examples of FIGS.
FIG. 2 is a cross-sectional view of a portion orthogonal to a drive shaft 11. FIG.
5A and 5B, the air supply port 24 is provided in the upper part of the discharge case 20 of the powder pump unit according to the embodiment of FIG. 5, and the air tube 624 is supplied from an air pump (air supply means) 600 (not shown). Air through the air supply port 24
To prevent the toner and aggregates remaining on the mesh member 30 from blowing off, thereby preventing clogging of the mesh member. FIG. 11C shows a configuration in which the air supply port 24 is provided at the lower part of the side surface of the discharge case 20.
(A) Unlike (b), since the air supply port 24 is closer to the mesh member 30 and supplies air from the lateral direction, the toner and aggregates on the mesh member 30 can be more effectively removed. Can be. FIGS. 11A and 11B
In the embodiment of (c), the air pump and the air supply port 24 are provided.
These constitute the cleaning means. The air pump 60
0 and a means for controlling the operation of the powder pump 1 are separately provided, and the air pump is operated when the screw pump is stopped (when suction force is not generated). Clogging of the mesh member 30 can be reliably prevented. That is, clogging of the mesh member due to removal of the aggregated toner for a long time can be prevented at any time, and the performance of the developer transfer device can be maintained for a longer time. In addition, when the means for controlling the operation of the air pump 600 and the means for controlling the drive of the powder pump are separately provided, if the air pump is operated immediately after the drive of the powder pump is stopped, the powder Foreign matter remaining on the mesh member after the body pump is stopped can be removed, thereby reliably preventing clogging of the mesh member. Accordingly, clogging of the mesh member due to the long-term operation of removing the aggregated toner is prevented at any time, and the performance of the developer transfer device can be maintained for a longer time. In each of the above embodiments, a configuration may be adopted in which a plurality of mesh members are provided. With this configuration, clogging of the mesh member due to the long-term removal of the aggregated toner is prevented, and the performance of the developer transfer device can be maintained for a long time.

[0013]

As described above, according to the first aspect of the present invention,
A mesh member that regulates the particle size of the toner supplied to the developing device is provided in the middle of the transfer path from the powder pump to the developer supply port of the developing device. In addition, it is possible to prevent an abnormal image due to the transfer of the aggregated toner generated by passing through the powder pump to the paper. According to the second aspect of the present invention, since the mesh member is provided near the discharge port of the suction type screw pump, it is possible to efficiently remove the aggregated toner generated by passing through the suction type powder pump. It is possible to prevent an abnormal image due to the transfer of the aggregated toner generated by the passage onto the paper. According to the third aspect of the present invention, a cleaning member is attached to the drive shaft drive shaft for driving the suction type screw pump to rotate and drive the drive shaft to rotate to drive and remove the developer abutting on and adhering to the mesh member. Therefore, foreign matter on the mesh member can be removed and clogging can be prevented. For this reason, clogging of the mesh member due to the long-term operation of removing the aggregated toner is prevented at any time, and the performance of the developer transfer device can be maintained for a long time. Claim 4
According to the invention, since the cleaning member is a thin plate member, an elastic member, or a brush attached to the drive shaft of the suction screw pump, clogging of the mesh member can be reliably prevented. For this reason, clogging of the mesh member due to the long-term operation of removing the aggregated toner is prevented at any time, and the performance of the developer transfer device can be maintained for a long time. According to the fifth aspect of the invention, the discharge case provided with the developer supply port is provided with the discharge port and the storage case for discharging and storing the residue remaining on the mesh member. The residue is removed, the discharge path is prevented from being blocked by foreign matter remaining on the mesh member due to long-time use, and the performance of the developer transfer device can be maintained for a longer time.

According to the invention of claim 6, the powder pump comprises:
The discharge type screw pump is provided at a position distant from the developing device, and the mesh member is provided in the vicinity of the discharge port of the discharge type screw pump. Can be removed. Therefore, it is possible to prevent an abnormal image due to the transfer of the aggregated toner generated by passing through the discharge type powder pump to the paper. According to the seventh aspect of the present invention, since the air supply means for blowing air to the mesh member to remove foreign matter remaining on the mesh member is provided, it is possible to reliably prevent the mesh member from being clogged. Accordingly, clogging of the mesh member due to removal of the aggregated toner for a long time can be prevented at any time, and the performance of the replenishing device can be maintained for a long time. According to the invention of claim 8, means for controlling the operation of the air supply means and means for controlling the drive of the powder pump are separately provided, and the air supply means is operated when the powder pump is stopped. Accordingly, clogging of the mesh member can be reliably prevented. Accordingly, clogging of the mesh member due to the long-term operation of removing the aggregated toner is prevented at any time, and the performance of the present developer transfer device can be maintained for a longer time. According to the invention of claim 9, a means for controlling the operation of the air supply means and a means for controlling the drive of the powder pump are separately provided, and the air supply means is operated immediately after the driving of the powder pump is stopped. Thus, it is possible to reliably prevent the mesh member from being clogged. Further, clogging of the mesh member due to removal of the aggregated toner for a long time is prevented as needed, and the performance of the apparatus can be maintained for a longer time. According to the tenth aspect of the present invention, since the mesh member is provided in a plurality of stages, clogging of the mesh member can be more effectively prevented. Therefore, clogging of the mesh member due to removal of the aggregated toner for a long time is prevented, and the performance of the present apparatus can be maintained for a long time.

[Brief description of the drawings]

FIG. 1 is an exploded cross-sectional view illustrating a configuration of a discharge type developer transfer device.

FIG. 2 is an explanatory diagram of a suction type toner supply device.

FIG. 3 is an explanatory diagram of a suction type toner supply device.

FIG. 4 is a diagram showing an example of an embodiment of an apparatus that conveys toner only with air.

FIG. 5 is an explanatory diagram of a powder pump unit of the developer transfer device of FIG. 2 or FIG. 3;

FIG. 6 is a perspective view of FIG. 5;

FIG. 7 is a main part configuration diagram of a developer transfer device according to another embodiment of the present invention.

FIG. 8 is a main part configuration diagram of a developer transfer device according to another embodiment of the present invention.

FIG. 9 is a cross-sectional view showing the configuration and operation of a developer transfer device according to another embodiment of the present invention.

FIG. 10 is a diagram illustrating the configuration and operation of a developer transfer device according to another embodiment of the present invention.

FIG. 11 is an explanatory diagram of a configuration and operation of a developer transfer device according to another embodiment of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 powder pump, 2 female screw stator, 3 male screw rotor, 4 holder, 5 gaps, 6 outlet, 7 air supply port, 11 shaft, 20 discharge case, 30 mesh member, 32 cleaning member, 32 cleaning member, 34 Outlet, 600 air pump.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Junichi Matsumoto 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (Reference) 2H077 AA01 AA11 AA37 AC02 AC11 AC16 DA24 DA76 DB25 FA21 2H134 GA01 GB02 JA02 JA03 JA12 JA14 KA20 KB05 KB11 KH17

Claims (10)

[Claims] 1. A developer is transferred to a developing device by a powder pump having a female screw type stator having a double pitch spiral groove therein and a male screw type rotor rotatably fitted in the stator. In the developer transfer device, a mesh member that regulates the particle size of the toner supplied to the developing device is provided in the middle of the transfer path from the powder pump to the developer supply port of the developing device. Developer transfer device. 2. The method according to claim 1, wherein the powder pump is a suction screw pump provided near a developer supply port of the developing device, and the mesh member is provided near a discharge port of the suction screw pump. The developer transfer device according to claim 1, wherein: 3. A drive shaft for driving the suction type screw pump to rotate is provided with a cleaning member for cleaning the developer adhered to the mesh member by rotating the drive shaft. 3. The developer transfer device according to claim 2, wherein: 4. The cleaning member is a thin plate member or an elastic member attached to a drive shaft of a suction screw pump,
4. The developer transfer device according to claim 3, wherein the transfer device is a brush. 5. The discharge case provided with the developer supply port is provided with a discharge port and a storage case for discharging and storing a residue remaining on the mesh member. The developer transfer device according to any one of claims 2, 3, and 4. 6. The powder pump is a discharge screw pump provided at a position distant from the developing device,
2. The developer transfer device according to claim 1, wherein the mesh member is provided near a discharge port of the discharge screw pump. 7. The developer transfer device according to claim 1, further comprising an air supply unit that blows air onto the mesh member to remove foreign matter remaining on the mesh member. 8. A device for independently controlling the operation of the air supply unit and the unit for controlling the driving of the powder pump,
2. The developer transfer device according to claim 1, wherein said air supply means is operated when said powder pump is stopped. 9. A device for independently controlling the operation of the air supply unit and the unit for controlling the drive of the powder pump,
2. The developer transfer device according to claim 1, wherein the air supply unit is operated immediately after the driving of the powder pump is stopped. 10. The developer transfer device according to claim 1, wherein a plurality of mesh members are provided.