JP2002284345A - Screw pump and developer transfer device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance stability of a transfer amount and to improve durability by setting biting amount of a powder pump, in other words, a biting amount of a rotor into a stator, so that a suction pressure rises to 10 kPa or more and thereby improving conveyance force in a screw pump equipped with a female screw stator having a double-pitch spiral groove inside thereof and a male screw rotor rotatably inserted into the stator. SOLUTION: Assuming a cross sectional diameter of the rotor 3 as RA, an outside diameter thereof as RB, a minimum inside diameter of the stator 2 as Smin, and a maximum inside diameter thereof as Smax, a sectional area biting amount RA/Smin by a ratio of the cross sectional diameter RA of the rotor and the minimum inside diameter Smin of the stator is set RA/Smin>=1.07, and an outside diameter biting amount RB/(Smin+Smax) by a ratio of the outside diameter RB of the rotor and the inside diameter Smax of the stator is set RB/(Smin+Smax)>=1.06.

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 transfer device for transferring collected toner after transfer and transfer to a developing device or a waste toner container, and an improvement of a screw pump used for the transfer 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 source 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. Therefore, there has been a problem that the suction pressure (discharge pressure) is reduced due to wear of the rubber of the stator due to use over time, and the discharge of the toner (developer) is eventually stopped. Particularly, in a suction-type powder pump used for suction transfer of toner, there is a problem that the operating life is short because a suction pressure is not generated and a conveying force cannot be obtained unless the rotor and the stator have high sealing properties. Was.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and maintains powder and toner durability even when a powder pump is operated for a long period of time. Provide a body pump.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a first aspect of the present invention is a female screw type stator having a double pitch spiral groove therein, and a male screw rotatably fitted in the stator. A rotor having a cross-sectional diameter of RA and an outer diameter of R
B, when the minimum inner diameter of the stator is Smin and the maximum inner diameter is Smax, the cross-sectional penetration amount RA / Smin based on the ratio between the cross-sectional diameter RA of the rotor and the minimum inner diameter Smin of the stator.
Is set to RA / Smin ≧ 1.07, and the outer diameter bite amount RB is determined by the ratio of the outer diameter RB of the rotor to the inner diameter Smax of the stator.
/ (Smin + Smax), RB / (Smin + Smax) ≧ 1.
06 is set. A second aspect of the present invention is a screw pump having a female screw type stator having a double pitch spiral groove therein and a male screw type rotor rotatably inserted in the stator. Is RA, its outer diameter is RB, the minimum inner diameter of the stator is Smin, and its maximum inner diameter is Smax,
The outer diameter biting amount RB / (Smin + Smax) based on the ratio of the outer diameter RB of the rotor to the minimum inner diameter Smax of the stator is represented by RB /
(Smin + Smax) ≧ 1.05, and the difference between the cross-section penetration amount and the outer diameter penetration amount is −0.005 ≦ RA / Smin−
RB / (Smin + Smax) ≦ 0.045. A third aspect of the present invention is a screw pump having a female screw type stator provided with a double pitch spiral groove therein and a male screw type rotor rotatably fitted in the stator. Is RA, the outer diameter is RB, the minimum inner diameter of the stator is Smin, and the maximum inner diameter is Smax. The outer diameter biting amount RB / is defined by the ratio of the outer diameter RB of the rotor to the minimum inner diameter Smax of the stator.
(Smin + Smax) is calculated as RB / (Smin + Smax) ≧ 1.0
6, and -0.002≤RA / Smin-RB / (Smin +
Smax) ≦ 0.04. Claim 4
The present invention is characterized by comprising a screw pump according to any one of claims 1, 2 and 3, and an air pump for supplying air to a discharge port of the screw pump. According to a fifth aspect of the present invention, the developer transfer device is a suction-type developer transfer device that sucks and transfers the two-component developing powder toner by the screw pump.

According to a sixth aspect of the present invention, the rotor is mainly made of polycarbonate. According to the seventh aspect of the invention, the cross-section bite amount RA / Smin and the outer diameter bite amount RB /
(Smin + Smax) and a difference RA / Smin-RB / (Smin + Smax) between the cross-section bite amount and the outer diameter bite amount are set, respectively. The invention according to claim 8 is characterized in that ethylene propylene rubber or chloroprene rubber is used as a main material of the stator. According to the ninth aspect of the invention, the cross-section bite amount RA / Smin and the outer diameter bite amount RB / (Sm
in + Smax) and the difference RA / Smin-RB / (Smin + Smax) between the cross-section bite amount and the outer diameter bite amount are respectively set. The invention according to claim 10 is characterized in that a stator mainly composed of rubber having a JIS A hardness of 50 or less is used as the stator. Claim 11
According to the invention, according to the difference in rubber hardness of the stator,
The cross-section bite amount RA / Smin, outer diameter bite amount RB
/ (Smin + Smax) and the difference RA / Smin-RB / (Smin + Smax) between the cross-section bite amount and the outer diameter bite amount are respectively set. In the invention of claim 12,
The rotation speed of the rotor is from 100 rpm to 400 rpm.
It is characterized in that it is used within the range. According to the thirteenth aspect of the present invention, the cross-section bite amount RA / Smin, the outer diameter bite amount RB / (Smin + Smax), and the difference RA between the cross-section bite amount and the outer diameter bite amount according to the difference in the pitch number between the rotor and the stator. / Smin-RB / (Smin + Smax). According to the fourteenth aspect of the present invention, the cross-section bite amount RA / Smin and the outer diameter bite amount RB /
(Smin + Smax) and the difference RA / Smin-RB / (Smin + Smax) between the cross-section bite amount and the outer diameter bite amount are set, respectively. In the invention according to claim 15, the cross-section bite amount RA depends on the type of the developer to be transferred.
/ Smin, outer diameter bite amount RB / (Smin + Smax), and difference RA / Smin- between cross-section bite amount and outer diameter bite amount
RB / (Smin + Smax) is set respectively. According to the sixteenth aspect of the present invention, the cross-section bite amount RA / Smin, the outer diameter bite amount RB / (Smin + Smax), and the difference RA / Smin between the cross-section bite amount and the outer bite amount according to the difference in the developer transfer distance. −RB / (Smin + Sma
x) is set respectively. According to the seventeenth aspect of the invention, the cross-section bite amount RA / Smin and the outer diameter bite amount RB / (Smin
+ Smax) and the difference RA / Smin-RB / (Smin + Smax) between the cross-section bite amount and the outer diameter bite amount.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. FIGS. 1A and 1B are cross-sectional views each showing an example of a powder pump (screw pump) constituting a transfer device according to an embodiment of the present invention, and FIGS.
FIG. 3 is a cross-sectional view of a screw pump, FIG. 3 is a diagram showing a relationship between a cross-section bite amount, an outer diameter bite amount, and a suction pressure of a powder pump, and FIG. FIG. 5 is a cross-sectional view, FIG. 5 is a diagram showing the relationship between the suction pressure and the toner supply amount for each type of toner, FIGS. 6 (a) to 6 (d) are diagrams showing Tables 1 to 4, FIGS. FIG. 8B is an overall view and a main part explanatory view showing a configuration example of a developer transfer device for collecting and recycling transfer residual toner, and FIGS. 8A and 8B show image formation using the developer transfer device of the present invention. FIG. 4 is an explanatory diagram of the apparatus and a toner storage tank.

FIG. 1A is an exploded sectional view showing the structure of a discharge type developer transfer device. The developer refers to a carrier or a toner, or a mixture of a carrier and a toner. Reference numeral 1a 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 an externally threaded rotor 3 rotatably fitted into the stator 2 and made of metal, resin, or the like. The rotor 3 is connected to the shaft 11 of the transfer screw 10 on the upstream side by a spring pin 12 or the like, and is driven to rotate by rotating the transfer screw 10.
By rotating the rotor, a discharge pressure is generated at the discharge port 6a. A tube (not shown) is connected to the discharge port 6a, and is transferred to a destination such as a developing device in a state where air is mixed. The periphery of the stator 2 is covered by a holder 4 fixed to a side plate (not shown), and a gap 5 is provided between the inner peripheral surface of the holder 4 and the outer peripheral surface of the stator 2. The gap 5 is communicated with a developer discharge port 6 a on the downstream side of the rotor 3. And holder 4
Is provided with an air supply port 7 communicating with the gap 5, and an air supply tube 16 from an air pump 15 is fitted into the air supply port 7. The air from the air pump 15 passes from the air supply port 7 through the gap 5 to the developer discharge port 6.
a, and fluidizes the developer, and smoothly and reliably discharges the developer in the direction of the arrow by the discharge pressure of the powder pump.

FIG. 1B is an exploded perspective sectional view showing a suction type developer transfer device 1b. Except that the shaft 11 is not provided with a transfer screw and that the holder 4 has no air supply port, it is the same as the discharge type developer transfer device 1a of FIG. By rotating the shaft 11 in the opposite direction to the discharge type powder pump 1a (or by using a rotor and a stator which are reversely wound to the discharge type),
A suction pressure is generated in the developer suction port 6b, and the sucked developer is discharged from the suction port 6b toward the suction shaft 11. In the above-described uniaxial eccentric screw pump, the stator 2 is made of a rubber material, and the rotor 3 made of metal or resin rotates inside the stator 2 while sliding, so that the inner diameter of the stator 2 is worn with time. , The discharge pressure or the suction pressure decreases.

FIG. 2 is a sectional view showing a state where the rotor 3 is inserted into the stator 2. There are three types of bites between the rotor 3 and the stator 2, D 1, D 2, and D 3. The bite amount D1 is a bite amount between the cross section of the rotor 3 and the minimum inner diameter of the stator 2. The bite amount D3 is a bite amount between the cross section of the rotor 3 and the end R of the stator 2. The bite amount D2 is a bite amount between the outer diameter of the spiral of the rotor 3 and the inner diameter of the stator 2. From the experimental results by the present inventor, it was found that D1 and D2 are important for the discharge pressure and the suction pressure of the powder pump among the three bite amounts. The present invention has been made based on such findings. Hereinafter, D1 is referred to as a cross-section bite amount, and D2 is referred to as an outer diameter bite amount for convenience.

FIG. 3 shows the relationship between the cross-section bite amount, the outer diameter bite amount, and the suction pressure of the powder pump. Also in Japanese Patent Application Laid-Open No. 11-84873 (Ricoh Co., Ltd.), in the toner transfer discharge type powder pump, the cross-section bite amount is determined by the toner cohesion degree after passing the powder pump, and the outer diameter bite amount is determined by whether the toner can be transported. However, in the present invention, in order to further improve the transfer performance of the powder pump, the suction pressure is focused on, and the bite is performed based on data based on a test result. Optimized amount. Here, focusing on the suction pressure instead of the discharge pressure, and using the suction pressure as an index for improving the transport performance, the suction pressure is higher than the discharge pressure by an upper limit (101 kP).
This is because there is a) and the value range is small and measurement is easy. Conversely, if the discharge pressure is excellent, the initial pressure will be infinite with a good pump, and it will be difficult to perform appropriate measurement. A ratio RA / Smin between the rotor cross-sectional diameter RA and the minimum inner diameter Smin of the stator is used as the cross-section penetration amount D1, and a ratio between the rotor outer diameter RB and the minimum stator inner diameter Smin and the maximum inner diameter Smax is used as the outer diameter penetration amount D2. RB / (Smin +
Smax). Here, as the bite amount, not the value of the difference between the dimensions of the rotor and the dimensions of the stator, but the ratio is used when the dimensions of the rotor and the stator change,
That is, it is for obtaining the appropriate range of the biting amount regardless of the size of the powder pump. The inventor measured the suction pressure while variously changing the cross-section bite amount D1 and the outer diameter bite amount D2, and obtained the result as shown in FIG. Note that P in the figure is the maximum suction pressure of the powder pump (suction pressure at maximum load), D
a is the cross-section penetration amount, Db is the outer diameter penetration amount, ○ in the graph is suction pressure of 30 kPa or more, and ▲ is 20 to 30 k
Pa and △ indicate 10 to 20 kPa, and X indicates less than 10 kPa.

FIG. 5 is a table showing the relationship between the suction pressure and the toner supply amount when suction transfer is actually performed by the apparatus shown in FIG. A, B, and C are the results when the type of the toner in the cartridge and the condition of the lift (the distance lifted in the vertical direction) of the transfer member 20 are different. The fluidity of the toner varies depending on the amount of an external additive such as silica gel or titanium, the type of the resin of the toner, and the like, and also varies depending on the ambient temperature and humidity. In FIG. 5, the toner replenishment amount decreases when the suction pressure is low. The reason is that the toner is transferred or not, and the dispersion is large and unstable due to insufficient suction force. Means that the supply amount is decreasing. A is a toner Ta having relatively good fluidity when the toner is used for electrophotography, and has a condition that the agglomeration degree is about 5 to 20% and the height of the transfer member is 200 mm. Here, the cohesion degree is 150 μm, 75
The toner is passed through a sieve of μm and 45 μm while applying vibration for 20 seconds, and the weight of the toner remaining on each sieve is defined as x, y, and z, respectively, and the degree of aggregation (%) = (5x + 3y + z)
It is a value obtained by × 10. The condition A can be said to be a relatively easy condition in that the toner is sucked and discharged from the cartridge and the toner is transferred by the transfer member. The result is that toner transfer is possible for the first time at -3 kPa in order to transfer, but is within a range where the replenishment amount is stable at P ≦ -4 kPa or more.

B is a condition that the toner is the same kind of toner Ta as A, and that the head of the transfer member is 500 mm.
This is because the load at the time of transporting the toner is increased by an amount larger than A, and the pressure loss until the suction pressure of the powder pump is transmitted to the toner in the cartridge is large.
At Pa <P ≦ −4 kPa, suction is possible, but the variation in the replenishment amount is large, indicating that the replenishment amount is stable at P ≦ −10 kPa. In many cases, the cartridge of the image forming apparatus is placed at the bottom of the apparatus main body in order to improve the operability, and in most cases, the head of 500 mm, which is the condition of B, is sufficient. In that sense, even when the cartridges are freely laid out in the image forming apparatus, a sufficient toner replenishing function can be obtained by using a pump having a suction pressure condition corresponding to this. In other words, in the case of this toner, a stable toner supply amount can be obtained if the suction pressure is 10 kPa or more. Therefore, a region surrounded by a two-dot chain line in FIG. 3A, that is, RA / Smin ≧ 1.07 and RB / ( Smin + Sma
x) The rotor dimensions and the stator dimensions may be set such that ≧ 1.06.

C is Tb in which the toner has poor fluidity, and has a degree of aggregation of about 20 to 60%. 500 m lift
Under the condition of m, this is the worst condition for a toner supply device in an image forming apparatus. Therefore, the pressure loss was the largest, and suction was possible at −20 kPa <P ≦ −10 kPa, but it was an unstable region, and the supply amount varied widely. As described above, the replenishment amount converges to the maximum value at P ≦ −20 kPa. Therefore, by using a pump satisfying this condition, toner replenishment performance that can withstand use under the worst conditions can be obtained. In the case of C, RB / (Smin + Sma) surrounded by a two-dot chain line and a solid line and a broken line in FIG.
x) ≧ 1.05 and −0.05 ≦ RA / Smin-RB /
The dimensions of the rotor and the dimensions of the stator may be set so that (Smin + Smax) ≦ 0.045. Further, when considering that the suction pressure is reduced with the lapse of time as described above, it is known that when an operation time of about 50 hr or more is required, it is desirable that there be a suction pressure of 30 kPa or more initially. RB / (Smin + Smax) ≧ 1.06 surrounded by a two-dot chain line and a solid line and a broken line in FIG.
And 0 ≦ RA / Smin−RB / (Smin + Smax) ≦ 0.
The size of the rotor and the size of the stator may be set so as to be 035.

Here, in order to increase the suction pressure, it is necessary to increase the bite amount, and as a result, the torque increases,
The temperature rise also increases, and the toner that has passed through the powder pump tends 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. Therefore, it is desirable to appropriately select the range of the biting amount in consideration of the conditions such as the toner used, the lift, the transfer distance, and the required operating time. In accordance with the type and property of the developer to be transferred in this way, the cross-section bite amount, the outer diameter bite amount, and the difference between the cross-section bite amount and the outer bite amount are set, respectively. That is, the amount of bite of the powder pump is set in accordance with the fluidity and the cohesive change of the developer used, and the necessary suction pressure (discharge pressure) and the cohesive change can be prevented. As a result, it is possible to improve the stability and durability of the transfer amount of the powder pump. Further, the cross-section bite amount, the outer diameter bite amount, and the difference between the cross-section bite amount and the outer bite amount may be set according to the difference in the developer transfer distance. That is, by appropriately setting the bite amount of the powder pump according to the transfer distance of the developer, even if the transfer distance is long, a stable transfer amount is obtained,
Durability can be ensured. Further, the cross-section bite amount, the outer diameter bite amount, and the difference between the cross-section bite amount and the outer diameter bite amount may be set according to the difference in the height of the developer transfer path. That is, by setting the bite amount of the powder pump by the lift of the path for transferring the developer, a stable transfer amount can be obtained even when the lift is large.

Next, Table 1 shown in FIGS.
4 to 4 are the actual suction pressure (at maximum load) of the powder pump at the initial stage and the passage of time when the rotor material, the stator material, the stator rubber hardness, the rotor pitch (stator pitch), and the rotor speed are changed. It is a measurement result.
The unit of the numerical value of the suction pressure is kPa. Since the suction pressure of the powder pump varies depending on these conditions,
It is desirable to appropriately select the range of the digging amount depending on the difference between these conditions. The common test conditions in Tables 1 to 4 are: cross-section bite amount RA / Smin = 1.09, outer diameter bite amount RB / (Smin + Smax) = 1.07, rotor speed 200 rpm (Tables 1 to 3), rotor pitch number 4
(Tables 1, 2, and 4), rotor cross-section diameter 7, rotor material polycarbonate (Tables 2 to 4), and a stator using EPDM (ethylene propylene rubber, Tables 1, 3, and 4). The symbol of judgment is that the maximum suction pressure of the powder pump is 10 kPa
As described above, ○ at 4 to 10 kPa and × at less than 4 kPa. The determination criteria of 4 kPa and 10 kPa are the lower limit of the suction pressure at which the toner can be sucked, as described in FIG. Since the suction pressure (discharge pressure) during use of the powder pump over time varies depending on the material of the rotor, by setting a suitable bite amount, a stable transfer amount over time can be obtained even when the rotor material is changed. Thus, the durability can be improved. For example, when a rotor made of polycarbonate is used as the main material for the rotor 3, by setting the amount of bite of the powder pump so as to increase the suction pressure (discharge pressure), the resin rotor which has conventionally had a problem in durability is used. As a result, the toner can be reliably suctioned and transferred over time, and the cost of the powder pump can be reduced.

As shown in Table 2, the suction pressure (discharge pressure) of the powder pump over time varies depending on the material of the stator, but the material of the stator is changed by setting an appropriate bite amount. In this case, a stable transfer amount can be obtained over time, and excellent durability can be ensured. For example, by setting the amount of bite into the powder pump so that the suction pressure (discharge pressure) is high, and using ethylene propylene rubber or chloroprene rubber excellent in toner resistance and wear resistance as the material of the stator, The durability of the powder pump can be improved. Also, by setting the amount of biting of the powder pump so as to increase the suction pressure (discharge pressure) and reducing the rubber hardness of the stator, the stress during operation can be reduced, and the amount of wear can be reduced. In addition, the durability of the powder pump can be improved. In addition, the suction pressure (discharge pressure) during use of the powder pump over time fluctuates according to the rubber hardness of the stator, but by setting an appropriate bite amount, even when the rubber hardness of the stator is changed, A stable transfer amount can be obtained and durability can be obtained. Next, as can be seen from Table 4, the rotation speed of the rotor was set to 10
Used in the range of 0 rpm to 400 rpm. Therefore, a high suction pressure can be stably obtained over time by using the rotor rotation speed in the above range and setting the bite amount. Next, as shown in Table 3, the suction pressure (discharge pressure) of the powder pump fluctuates according to the pitch number of the rotor and the stator, but the bite amount is set by setting the bite amount according to the pitch number. Even if it is desired to reduce the size and reduce the size, or if the number of pitches is increased in order to improve the durability, a stable conveyance force can be obtained.
Further, by setting the bite amount according to the usage time of the powder pump, the durability performance thereof can be adjusted.

FIG. 4 is a cross-sectional view of an example in which the toner supply device (developer transfer device) according to one embodiment of the present invention is applied to a new toner supply device. The powder pump (screw pump) 1 is of a suction type, and is the same as that of FIG. Since the nozzle 510 and the transfer tube 20 forming the toner path connecting the toner cartridge 400 to the powder pump 1 are hermetically sealed, the suction force generated by the operation of the powder pump 1 is transmitted through the transfer tube 20 and the nozzle 510. The toner is transferred to the toner 450 in the toner cartridge 400 and the toner can be transferred. At this time, air is supplied to the toner in the cartridge 400 through the nozzle 510 by the air pump 600. Powder pump 1
After the toner in the vicinity of the nozzle is sucked, a bridging phenomenon (a cavity is formed in the portion of the lost toner) occurs in the cartridge, and the toner supply amount becomes unstable, or the toner remaining amount in the cartridge becomes extremely large. But sometimes
By supplying air to the inside of the cartridge, the toner is stirred and fluidized, and the above-described cross-linking phenomenon of the toner is 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 cartridge can be reduced. At this time, the cartridge 400 can be provided with a gas permeable filter 440 above the toner storage member 410, whereby the air supplied from the air pump 600 (air supply means) reverses the inside of the cartridge. It serves to reduce the rise to positive pressure.

The toner sucked by the powder pump 1 is
Toner introduction hole 201 provided in a part of developing device 200
It falls further into the developing device. In the case of the developing device using the two-component developing method, the replenished toner (aspirated toner) is stirred and mixed with the developer in the developing device to have a uniform developer concentration and an appropriate charge amount. The transfer member 20 is, for example, a tube having an inner diameter of about 4 to 7 mm and made of a rubber material (ex. Polyurethane, nitrile, EPDM, silicon, etc.) or a plastic material (polyethylene, nylon, etc.) which is flexible and has excellent toner resistance. It is very effective to use. Reference numeral 500 denotes a container holder (cartridge holder), which holds the protective case 401 of the cartridge (toner container) 400. 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 formed as a single-layer or multi-layer sheet-like flexible sheet made of resin such as polyethylene or nylon or paper (having a thickness of about 80 to 200 μm), as in the case of origami manufacturing. It is made in the shape of a closed bag-shaped container without air inflow and outflow. The base member 420 is made of resin,
The nozzle 510 includes a case 421 such as paper and a seal 422 such as a sponge. The nozzle 510 has a toner discharge hole 512 at the tip and a toner discharge path 513 at the shaft core. Cartridge 40
0 is set in the container holder, the nozzle 510
Is inserted into the seal 422 of the base member, and the seal 4
The nozzle 22 is in close contact with the nozzle 510 to prevent toner leakage from the cartridge to the outside of the apparatus.

FIGS. 7A and 7B are an overall view and a main part explanatory view showing an example of the construction of a developer transfer device for collecting and recycling transfer residual toner. In the case of the photosensitive drum 701, the developing device 702, the transfer device 705, and the cleaning device 711, which are conventionally known electrophotographic image forming processes, the developing device 702 supplies an electrostatic latent image formed on the photosensitive drum 701. And transfer the toner image to the transfer paper 710 fed by the paper feeding means,
The untransferred toner remaining on the top is removed and collected by the cleaning device 711. The toner collected by the cleaning device 711 is collected by the coil screw 713 to the collected developer transfer device 720. Further, the transfer device 7
Residual toner adhering to the transfer member 05 is also collected from the cleaning means in the transfer device and the coil screw 714 to the collection developer transfer device 720. The collected toner is transferred to the developing device 702 via the transfer tube 735 by the collected developer transfer device 720, and the collected toner is recycled. The recovered developer transfer device 720 is provided with the powder pump 1, and supplies air near the powder pump outlet via an air tube 16 by an air pump 15. This is an example using the discharge type powder pump of FIG. Transfer residual recovery toner generally has a very poor fluidity compared to new toner, so high powder pumping performance is required.Therefore, as described above, set the bite-in amount in the appropriate range and increase the high discharge pressure. It is effective to use a powder pump that has it.

Next, FIG. 8A is an image forming apparatus having a large-capacity toner replenishing device, and FIG. 8B is a structural example of a large-capacity toner replenishing device. Reference numeral 910 denotes an image forming apparatus (copier,
Printer 800 is an external large-capacity toner supply device. Agitator 831 for stirring toner 890 in toner storage tank 825, powder pump 810 (corresponding to powder pump 1 in FIG. 1A) provided at the lowermost end of the tank, and moving the toner in the tank. The toner in the tank is discharged with less residual toner by the transport screw 830. Further, when the toner in the tank runs out, the toner can be replenished from the replenishing port 833. At this time, an air vent filter 832 for discharging air inside is provided. Reference numeral 840 denotes a collection cartridge, which is used as a collection container after the toner container for replenishing toner in the above-described tank is used. Although not shown, the image forming apparatus 910 is provided with the above-described developer transfer device for recovering the transfer residual toner,
The collected toner sent by the collected developer transfer device is collected by the collection cartridge 840 through the transfer tube via the collection port 841 from the arrow F in FIG. The powder pump 810 is the discharge pump shown in FIG.
The air supplied from around the outlet of the powder pump mixes with the toner discharged from the powder pump, thereby enabling smooth toner transfer. This developer transfer device is an optional device of the image forming device, and is set to be worn by frequently used users.
Of course, it is needless to say that this apparatus can be built into the image forming apparatus and provided as standard equipment. Since the replenishment toner has different fluidity depending on its type, it is desirable to appropriately set the bite amount of the powder pump according to the type of toner as described above.

[0022]

As described above, according to the first aspect of the present invention, there is provided a female screw type stator having a double pitch spiral groove therein,
In a screw pump having a male screw rotor rotatably inserted into the stator, the amount of bite of the powder pump (the amount of bite between the rotor and the stator) is set so as to increase the suction pressure (10 kPa or more). Therefore, by obtaining a high conveyance force, the stability of the transfer amount can be increased, and the durability can be improved. According to a second aspect of the present invention, the powder pump biting amount is set so as to further increase the suction pressure (20 kPa or more), and a high transfer force is obtained, thereby improving the stability of the transfer amount even when used over time. Can be. That is, it is possible to further improve the stability of the transfer amount and the durability of the powder pump. According to the third aspect of the present invention, the amount of biting into the powder pump is set so as to further increase the suction pressure (30 kPa or more). Thus, a powder pump having the highest durability can be obtained. According to the fourth aspect of the present invention, the powder pump bite amount is set so as to increase the suction pressure (discharge pressure), so that the developer is reliably transferred and the stability of the replenishment amount is maintained even over time. Made it possible. That is, the stability and durability of the transfer amount of the developer discharge type transfer powder pump can be improved. Claim 5
According to the invention, the developer transfer device is a suction type developer transfer device that suctions and transfers the two-component developing powder toner by a screw pump. Therefore, by setting the powder pump bite amount so as to increase the suction pressure, the toner can be reliably suctioned and transferred even when used over time, and the transfer amount can be stabilized.
The durability can be improved. The invention according to claim 6 uses a rotor mainly made of polycarbonate as the rotor. Accordingly, by setting the powder pump biting amount so as to increase the suction pressure (discharge pressure), it is possible to reliably transfer the toner over time of the resin rotor, which has conventionally had a problem in durability, The cost of the pump can be reduced. According to the invention of claim 7, the cross-section bite amount, the outer diameter bite amount, and the difference between the cross-section bite amount and the outer diameter bite amount are set according to the difference in the material of the rotor.
In other words, the suction pressure (discharge pressure) during use of the powder pump over time fluctuates according to the rotor material. By setting an appropriate bite amount, the transfer amount can be stable over time even when the rotor material is changed. Can be obtained.

According to the invention of claim 8, ethylene propylene rubber or chloroprene rubber is used as a main material of the stator. That is, by setting the amount of bite into the powder pump so as to increase the suction pressure (discharge pressure) and using ethylene propylene rubber or chloroprene rubber excellent in toner resistance and abrasion resistance, the durability of the powder pump is improved. Performance can be improved. According to the ninth aspect of the invention, the cross-section bite amount, the outer diameter bite amount, and the difference between the cross-section bite amount and the outer bite amount are set according to the difference in the material of the stator. In other words, the suction pressure (discharge pressure) during use of the powder pump over time fluctuates depending on the material of the stator, but by setting an appropriate bite amount, the transfer amount can be stable over time even when the material of the stator is changed. , And excellent durability can be secured. Claim 10
In the invention, the stator is JIS A hardness 50
The following rubber-based stator was used. That is, the amount of biting into the powder pump is set so as to increase the suction pressure (discharge pressure) and the rubber hardness of the stator is reduced, so that the stress during operation can be reduced, and the amount of wear can be reduced. In addition, the durability of the powder pump can be improved. According to the eleventh aspect of the present invention, the cross-section bite amount, the outer diameter bite amount, and the difference between the cross-section bite amount and the outer diameter bite amount are set according to the difference in the rubber hardness of the stator. In other words, the suction pressure (discharge pressure) during use of the powder pump over time fluctuates according to the rubber hardness of the stator. However, by setting an appropriate bite amount, even when the rubber hardness of the stator is changed, A stable transfer amount can be obtained and durability can be obtained. Claim 12
According to the invention, the rotation speed of the rotor is increased from 100 rpm to 40 rpm.
Used in the range of 0 rpm. Therefore, a high suction pressure can be stably obtained over time by using the rotor rotation speed in the above range and setting the bite amount.

According to the thirteenth aspect of the present invention, the cross-section bite amount, the outer diameter bite amount, and the difference between the cross-section bite amount and the outer diameter bite amount are set according to the difference in the pitch number between the rotor and the stator. That is, the suction pressure (discharge pressure) of the powder pump varies according to the pitch number of the rotor and the stator,
By setting the bite amount according to the number of pitches, a stable conveyance force can be obtained even when the number of pitches is to be reduced to reduce the number of pitches or when the number of pitches is increased to improve durability. According to the invention of claim 14, the cross-section bite amount according to the operating time of use of the screw pump,
The outer diameter penetration amount and the difference between the cross-section penetration amount and the outer diameter penetration amount were set respectively. That is, the durability can be adjusted by setting the bite amount according to the usage time of the powder pump. In the invention according to claim 15, the cross-section bite amount, the outer diameter bite amount, and the difference between the cross-section bite amount and the outer diameter bite amount are set according to the type of the developer to be transferred. That is, the amount of bite of the powder pump is set in accordance with the fluidity and the cohesive change of the developer used, and the necessary suction pressure (discharge pressure) and the cohesive change can be prevented. As a result, it is possible to improve the stability and durability of the transfer amount of the powder pump. According to the sixteenth aspect of the invention, the cross-section bite amount, the outer diameter bite amount, and the difference between the cross-section bite amount and the outer diameter bite amount are set in accordance with the difference in the developer transfer distance. That is, by appropriately setting the bite amount of the powder pump according to the transfer distance of the developer, a stable transfer amount can be obtained even when the transfer distance is long, and durability can be secured. According to the seventeenth aspect of the present invention, the cross-section bite amount, the outer diameter bite amount,
And the difference between the cross-section penetration amount and the outer diameter penetration amount is set respectively. That is, by setting the bite amount of the powder pump by the lift of the path for transferring the developer, a stable transfer amount can be obtained even when the lift is large.

[Brief description of the drawings]

FIGS. 1A and 1B are cross-sectional views each showing an example of a screw pump constituting a transfer device according to an embodiment of the present invention.

FIG. 2 is a sectional view of a screw pump.

FIGS. 3 (a), (b) and (c) show the relationship between the cross-section bite amount and the outer diameter bite amount, and the suction pressure of the powder pump at that time.

FIG. 4 is a sectional view showing an application example of the developer transfer device and the screw pump of the present invention.

FIG. 5 is a diagram illustrating a relationship between a suction pressure and a toner supply amount for each type of toner.

FIGS. 6A to 6D show Tables 1 to 4. FIGS.

FIGS. 7A and 7B are an overall view and a main part explanatory view showing a configuration example of a developer transfer device for collecting and recycling transfer residual toner.

FIGS. 8A and 8B are explanatory views of an image forming apparatus and a toner storage tank to which the developer transfer device of the present invention is applied.

[Explanation of symbols]

1a, 1b powder pump (screw pump), 2 stators, 3 rotors, 4 holders, 5 gaps, 10 transfer screws, 11 shafts, 12 spring pins, 6a discharge port, 6b developer suction port, 7 air supply port, 15
Air pump, 16 air supply tube.

Continued on the front page (72) Inventor Nobuo Kasahara 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Nobuo Iwata 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. F term (reference) 2H077 AA01 AA11 AA37 AC02 AC11 AC16 2H134 GA01 GB02 JA02 JA03 JA11 3F047 AA04 AA11 CA02 DA00 DA05

Claims (17)

[Claims] 1. A screw 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, wherein the rotor has a cross-sectional diameter of RA, Assuming that the outer diameter is RB, the minimum inner diameter of the stator is Smin, and the maximum inner diameter is Smax, the cross-sectional penetration amount RA / Smin based on the ratio of the rotor cross-sectional diameter RA to the stator minimum inner diameter Smin is RA / Smin. ≧
1.07, and the outer diameter biting amount RB / (Smin + Smax) based on the ratio of the outer diameter RB of the rotor to the inner diameter Smax of the stator is calculated as RB / (S
(min + Smax) ≧ 1.06. 2. A screw pump having a female screw type stator having a double pitch spiral groove therein and a male screw type rotor rotatably inserted in the stator, wherein a cross-sectional diameter of the rotor is RA. When the outer diameter is RB, the minimum inner diameter of the stator is Smin, and the maximum inner diameter is Smax, the outer diameter biting amount RB / (Smin + Smax) based on the ratio of the outer diameter RB of the rotor to the minimum inner diameter Smax of the stator is obtained. , RB /
(Smin + Smax) ≧ 1.05, and the difference between the cross-section penetration amount and the outer diameter penetration amount is −0.00
5 ≦ RA / Smin−RB / (Smin + Smax) ≦ 0.04
5. A screw pump according to 5, wherein 3. A screw pump having a female screw type stator having a double pitch spiral groove therein and a male screw type rotor rotatably inserted in the stator, wherein the rotor has a cross-sectional diameter of RA. When the outer diameter is RB, the minimum inner diameter of the stator is Smin, and the maximum inner diameter is Smax, the outer diameter biting amount RB / (Smin + Smax) based on the ratio of the outer diameter RB of the rotor to the minimum inner diameter Smax of the stator is obtained. RB / (Smin + Smax) ≧ 1.06, and −0.002 ≦ RA / Smin−RB / (Smin + Smax)
≦ 0.04. Screw pump. 4. A developer transfer comprising the screw pump according to claim 1, and an air pump for supplying air to a discharge port of the screw pump. apparatus. 5. The developer transfer device according to claim 4, wherein the developer transfer device is a suction type developer transfer device that sucks and transfers the two-component developing powder toner by the screw pump.
3. The developer transfer device according to claim 1. 6. The rotor according to claim 1, wherein the rotor is mainly made of polycarbonate.
The screw pump or the developer transfer device according to any one of claims 1 to 6. 7. The cross-section bite amount RA / Smin, the outer diameter bite amount RB /, depending on the material of the rotor.
(Smin + Smax) and a difference RA / Smin-RB / (Smin + Smax) between the cross-section bite amount and the outer diameter bite amount are set respectively.
Or the screw pump or the developer transfer device according to any one of the above items 6. 8. The screw according to claim 1, wherein ethylene propylene rubber or chloroprene rubber is used as a main material of the stator. Pump or developer transfer device. 9. A cross-section bite amount RA / Smin and an outer diameter bite amount RB / (Sm) according to a difference in the material of the stator.
wherein the difference RA / Smin-RB / (Smin + Smax) between the cross-section bite amount and the outer diameter bite amount is set, respectively.
The screw pump or the developer transfer device according to any one of claims 7 and 8. 10. The stator according to claim 1, wherein said stator is a stator mainly composed of rubber having a JIS A hardness of 50 or less. The screw pump or the developer transfer device according to claim 1. 11. The cross-section bite amount RA / Smin, the outer diameter bite amount RB / (Smin + Smax), and the difference RA / Smin-RB between the cross-section bite amount and the outer bite amount according to the difference in rubber hardness of the stator. / (Smin + Smax)
Is set, respectively.
The screw pump or the developer transfer device according to any one of 4, 5, 6, 7, 8, 9, and 10. 12. The rotation speed of the rotor is set at 100 rpm.
2. The method according to claim 1, wherein the light is used in a range of from 1 to 400 rpm.
The screw pump or the developer transfer device according to claim 1. 13. The cross-section digging amount RA / Smin, the outer-diameter digging amount RB / (Smin + Smax), and the difference RA / Smin between the cross-section digging amount and the outer-diameter digging amount according to the difference between the pitch numbers of the rotor and the stator. −RB / (Smin + S
max) is set respectively.
The screw pump or the developer transfer device according to any one of 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12. 14. The cross-section bite amount RA / Smin, the outer diameter bite amount RB / (Smin + Smax), and the difference RA / Smin-RB between the cross-section bite amount and the outer bite amount according to the operating time of use of the screw pump. / (Smin + Sma
x) is set, respectively.
3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 1
4. The screw pump or the developer transfer device according to claim 3. 15. The cross-section bite amount RA / Smin, the outer diameter bite amount RB /, depending on the type of developer to be transferred.
(Smin + Smax) and a difference RA / Smin-RB / (Smin + Smax) between the cross-section bite amount and the outer diameter bite amount are set respectively.
The screw pump or the developer transfer device according to any one of 6, 7, 8, 9, 10, 11, 12, 13, and 14. 16. The cross-section bite amount RA / Smin and the outer diameter bite amount RB / are determined in accordance with the difference in the developer transfer distance.
(Smin + Smax) and a difference RA / Smin-RB / (Smin + Smax) between the cross-section bite amount and the outer diameter bite amount are set respectively.
The screw pump or the developer transfer device according to any one of 6, 7, 8, 9, 10, 11, 12, 13, and 14. 17. A cross-section bite amount RA / Smin and an outer diameter bite amount RB according to a difference in a height of a developer transfer path.
/ (Smin + Smax), and the difference RA / Smin-RB / (Smin + Smax) between the cross-section bite amount and the outer diameter bite amount, respectively, are set.
6, 7, 8, 9, 10, 11, 12, 13, 14 or 1
6. The screw pump or the developer transfer device according to any one of 5.