JP2007183348A - Developer container and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developer container which facilitates the stabilization of toner concentration of a developer replenished in an image forming apparatus in which a developer obtained by mixing a toner with a carrier is replenished to a developing unit. <P>SOLUTION: When a premix toner is packed in an easily deformable developer cartridge, the volume ratio of a space above the upper surface of the toner in the developer cartridge to the whole volume is set to ≥12% so that the toner can stably be discharged from the developer cartridge until the toner disappears. The developer cartridge is made of a material having a particularly small moisture vapor permeability. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic apparatus using a two-component developer in an electrophotographic apparatus such as a copy, FAX, or printer, and a developer storage container filled with a developer in which a carrier is mixed with toner, and the developer as a developer. The present invention relates to a technology for supplying a developing device from a storage container.

The developer filled in the two-component developing device gradually wears the carrier surface coating layer as the image is output, or conversely, the toner resin and additives adhere to the coating layer and charge the toner gradually. In order to cause background stains and toner scattering when the level drops below a certain level, service personnel have regularly visited and exchanged users. For this reason, maintenance costs have been incurred and the copy unit price has become high. In order to solve this problem, a developing method has been proposed in which a carrier is automatically and periodically replenished separately from the replenishing toner (see, for example, Patent Document 1). However, this method requires a space for storing new developer and a means for supplying the developer separately from the toner cartridge and the replenishing means, leading to an increase in the size and cost of the apparatus.
Therefore, in order to solve this problem, in the developer supply container having an opening for discharging the stored developer, the developer supply container is provided so as to protrude at least from the inner wall of the container and spirally toward the opening. The developer replenished to the developer receiving device from the opening as the developer replenishing container rotates, and the developer replenishes the carrier and toner. There has been proposed a developer replenishing system containing 1 to 30 parts of toner in a weight ratio of 1 to 30 parts of toner and having a true specific gravity of 2.5 to 4.5 (see, for example, Patent Documents). 2). As a result, even in long-term use, there is no toner scattering, the toner charge amount in the developing device is stable, excellent image uniformity and gradation, and a replenishment capable of obtaining a high-quality image without fogging. Development unit can be provided.

  A developer replenishment kit detachably attached to the image forming apparatus, the container containing the developer, a discharge port provided in the container for discharging the developer, and rubbing the inner surface of the container And a flexible member that stirs the developer and conveys the developer to the discharge port. The developer is composed of a mixture of toner and substantially spherical spacer particles, and the average particle diameter (D50) of the spacer particles is determined. A developer replenishment kit characterized by being larger than the weight average particle diameter (D4) of the toner is disclosed (for example, see Patent Document 3). This reduces the remaining amount of developer remaining in the developer replenishment kit and prevents toner coarsening that causes image defects when the developer in the developer replenishment kit is stirred and transported. Can do.

Patent Documents 2 and 3 propose a method in which a developer (carrier) is placed in a replenishment toner of a bottle cartridge that rotates and supplies toner.
However, in a replenishment method that employs a bottle container that is expected to be composed of a rigid material such as a resin, the toner and the carrier are separated, and only the carrier is supplied concentrated first or later. The amount of toner in the developer is not stable, the toner density control in the developing device becomes unstable, and an abnormal image is generated. In addition, toner agglomerates were produced in the bottle as the bottle rotated, and abnormal images such as white spots were generated.

Japanese Patent Publication No. 60-018065 JP 2004-29306 A JP 2004-333514 A

  The present invention provides a developer storage container and an image forming apparatus for promoting stabilization of the toner concentration in the replenished developer in an image forming apparatus that replenishes the developing device with a developer in which a carrier is mixed with toner. That is.

According to the first aspect of the present invention, in the developer storage container for storing the developer containing the toner and the carrier, the developer is connected to the suction type powder pump, and the developer is carried out by suction of the powder pump. Features.
In a second aspect of the present invention, in the developer storage container for storing the developer containing toner and carrier, the developer is connected to a suction type powder pump, and the developer is carried out by suction of the powder pump. Features.
According to a third aspect of the present invention, in the developer storage container according to the first or second aspect, the developer is measured after standing after standing for 24 hours or more after being filled with the developer. The porosity in the storage container is 12% or more.
According to a fourth aspect of the present invention, in the developer container according to any one of the first to third aspects, a weight ratio of the carrier to the developer is 3 wt% to 20 wt%. .

According to a fifth aspect of the present invention, in the developer storage container according to any one of the first to fourth aspects, the toner charge amount of the developer stored in the developer storage container is adjusted within a certain range. It is characterized by being.
According to a sixth aspect of the present invention, in the developer storage container of the fifth aspect, the adjustment is performed by adjusting the toner charge amount of the encapsulated developer in which the developing device encloses the toner charge amount of the stored developer. It is characterized by the above.
According to a seventh aspect of the present invention, in the developer storage container according to the sixth aspect, the adjustment is a step in which the developer is stored in the storage portion by all or part of the toner charge amount in the developer. It is performed by being imparted by a triboelectric charging action that occurs in the inside.
According to an eighth aspect of the present invention, in the developer container according to any one of the first to seventh aspects, the toner includes a lubricant having a weight ratio of 0.3 to 3.0 wt% with respect to the toner. It is characterized by including.
According to a ninth aspect of the invention, in the developer container according to the seventh or eighth aspect, the developer has an accelerated aggregation degree of 10% or less.

According to a tenth aspect of the present invention, in the developer storage container according to any one of the first to ninth aspects, the water vapor transmission rate per 24 hours of the material is 1.0 g / m ² or less. Features.
According to an eleventh aspect of the present invention, the developer container according to any one of the first to tenth aspects, the powder pump, and the developer container are in communication with each other, and the powder pump is connected to a part of the path. The developer is replenished from the developer storage container via the developer transport path provided to the developer and the developer transport path, and a part of the included developer contained in response to the replenishment is discharged out of the apparatus. An image forming apparatus having at least a developing device of the type.
According to a twelfth aspect of the present invention, in the image forming apparatus according to the eleventh aspect, the developer transport path is configured by using a tubular member made of a deformable flexible material. .
According to a thirteenth aspect of the present invention, in the image forming apparatus according to the eleventh or twelfth aspect, a hopper for storing the developer is provided between the powder pump and the developing device. .

  According to the present invention, there is provided a developer storage container and an image forming apparatus that can be carried out of the developer storage container without significantly changing the dispersion state of the carrier in the developer. be able to.

The best mode for carrying out the present invention will be described below with reference to the drawings. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims.
FIG. 1 is a diagram for explaining a volume-reduction toner replenishing method.
In the figure, reference numeral 1 is a pump clutch, 2 is a hopper for storing developer, 3 is a hopper clutch, 4 is a suction type powder pump, 5 is a toner end detector (TE sensor), and 6 is deformable. A tubular member made of a flexible material, 7 is a developer cartridge that is a developer container, 8 is a developer, 9 is a nozzle, and 10 is a developing device.
FIG. 2 is a view showing an example of the developer cartridge.
In the figure, reference numeral 70 is a developer cartridge, 71 is a bag-like member, 72 is a base part for receiving the nozzle on the main body side, 73 is in contact with the nozzle by insertion of the nozzle, and is pushed out by the nozzle to be inside the bag-like member 71 And a piston 74 for communicating the toner passage of the nozzle and a reinforcing plate for facilitating the folding action at a broken line f, which will be described later, during the suction action from the nozzle, and 74 for the toner discharge port, f Indicates a fold line that has been creased in advance when the bag-shaped member is manufactured.
The present invention is applied to the volume-reduction toner replenishing system shown in FIG.

The configuration of the above embodiment will be described in detail. The developer 8 is a developer that is replenished to the developing device. In this case, the mixing ratio of the toner and the carrier is set to be much larger for the toner than for the carrier. Specifically, the weight ratio of the carrier to the total amount of developer is set within a range of 3 wt% to 20 wt%. By setting the mixing ratio in such a range, when the developer 8 is supplied to the encapsulated developer contained in the developing device, the mixing ratio becomes a favorable ratio and is necessary for subsequent image formation. The toner density can be maintained. The developer cartridge 7 of the present invention employs a container made of a material that is flexible and deformable in a bag-like portion that is a storage part, and can be folded automatically by suction or manually after use. In FIG. 2, the reinforcing plate 74 attached to the front face makes it difficult for the front face to be deformed and bends from the side surface with the fold line f so that the storage portion is brought into a predetermined folded state when the volume is reduced by suction. There is an effect of inducing to occur. Returning to FIG. 1, the developer cartridge 7 is filled with the developer 8. The developer cartridge 7 is provided with a developer discharge port connected to the nozzle 9 at the bottom, and the developer 8 filled in the developer cartridge 7 falls by its own weight and collects at the developer discharge port. Come.
Note that the bag-like member 71 that is the developer storage portion does not necessarily have to be a flexible member, and only the side surface and the upper surface including the broken line f in the drawing that is the folding portion are made of a flexible material. The front surface and the back surface facing it may be made of a rigid material such as a resin or a metal thin plate.

  When it is determined from the output of a toner concentration sensor (not shown) installed in the developing device 10 that the toner concentration in the developing device 10 is low, the suction type powder pump (hereinafter simply referred to as a pump) 4 is driven ( In the example of the figure, the pump clutch 1 is connected and the pump 4 rotates). By driving the pump 4, the developer 8 is sucked into the pump 4 through a tubular member (hereinafter referred to as a flexible tube) 6 made of a deformable flexible material that connects the nozzle 9 and the pump 4. In FIG. 1, a hopper unit 2 for storing the developer is installed, and at the same time, the conveying screw of the hopper unit 2 is driven to supply toner from the hopper unit 2 to the developing device 10. However, by controlling the driving of the pump 4, it is possible to control the replenishment amount of the developer 8 according to the amount required by the developing device 10. Alternatively, a configuration in which toner is directly supplied to the developing device 10 may be employed. Specifically, the relationship between the predetermined driving time of the pump and the replenishment amount is grasped in advance, and the pump replenishes it in a fixed amount. The toner density sensor determines whether or not the toner density is sufficient at regular intervals, and when it is judged that the toner density is sufficient, the driving of the pump 4 is stopped (the pump clutch 1 is disengaged in this example) Supply stops.

Among the developer replenishment methods, there is a method in which a replenishment target is not a conventional toner but a developer including toner and a carrier in advance, and the developer is replenished. For convenience, this method will be referred to as a trickle supply method. In detail, in this method, the developer included in the developing device by the replenishment of the developer exceeds the predetermined amount, but the excess developer is configured to be discarded. Thus, the developer amount is maintained at a predetermined amount, and the carrier deteriorated by the image formation is discharged out of the apparatus. Thus, in the trickle replenishment system, the carrier can be automatically replaced with the old and new at the same time as the toner replenishment. The invention of Patent Document 1 is the same as the means for discarding excess developer, but differs from the trickle replenishment method described above in that it employs a method in which the carrier and toner are separately replenished and mixed in the developing device. . In the method of the invention of Patent Document 1, the storage container and the replenishment mechanism must be provided for both the toner and the carrier, and there is a problem of increasing the size of the apparatus.
One of the embodiments of the developer storage container in the present invention is to be mounted on a developing device adopting the above-mentioned trickle replenishment method. Hereinafter, the developing device 10 will be described as a trickle replenishing type developing device having a mechanism for discarding the above-described excess developer. The weight ratio of the carrier C in the internal developer contained in the developing device 10 is preferably about 87 to 97 wt%, and preferably about 90 to 95 wt% in terms of maintaining image density and suppressing background contamination. .

In the conventional replenishment method, in the replenishment of toner and carrier mixed toner from a rotating bottle whose spiral groove is cut in the bottle, the toner is transported to the bottle outlet while being stirred inside the bottle. As it is repeated, a carrier with a large specific gravity sinks to the inner wall surface on the lower side of the bottle. Since this carrier is in contact with or in the vicinity of the inner wall surface, the driving of the bottle is more easily transmitted than the toner at the center of the bottle, and as a result, the carrier is preferentially conveyed to the outlet along the spiral groove. Therefore, the carrier is selectively replenished first, the toner density control in the developing device becomes unstable, and an abnormal image is generated.
In the present invention, the developer 8 is scheduled to be transported out of the developer cartridge 7 by the suction action of the pump 4, and the spiral groove, which is an essential component of the rotating bottle, is adopted in the storage portion for storing the developer. There is no need. Therefore, the problem of selective sinking of the carrier into the spiral groove cannot occur. In addition, in a system in which a developer is simply put in a rigid container made of resin and the developer is carried out by free fall, it is necessary to reduce the developer discharge port from the viewpoint of discharging an appropriate amount without discharging too much at once. However, in that case, when the developer is likely to be clogged at the discharge port, it is expected that the discharge becomes insufficient because there is no correction action other than gravity. In the present invention, the suction force of the powder pump can ensure the correction action.
The above-described effects can be obtained regardless of whether the developer accommodating portion is a rigid body or a flexible one. However, the developer cartridge 7 of the present embodiment is additionally configured to constitute the developer accommodating portion. A material having flexibility that can be deformed is used for a part or all of the container. As a result, the volume of the storage portion is gradually reduced by the suction action of the pump 4, so that almost no stirring action occurs, and as a result The developer 8 mixed in a dispersed state before filling the agent cartridge 7 is carried out of the cartridge while maintaining a state relatively close to the dispersed state.

FIG. 3 is a diagram showing a result of measuring the carrier distribution in the developer cartridge when left in a stationary state.
In the figure, U represents the weight ratio of the carrier near the top, M the vicinity of the center, and B the bottom.
The weight ratio of the carrier C in the developing device 10 of the present embodiment is approximately 90 to 95 wt%. However, it is assumed that the carrier C filled in the developer cartridge 7 is replenished while sequentially replacing the deteriorated carrier. However, if the carrier abundance ratio is high, the rate at which new carriers are discarded increases, which is uneconomical. For example, a relatively small rate such as 5 to 10 wt% is preferable.
In the figure, after the developer cartridge 7 filled so that the carrier weight ratio of the developer 8 is 10 wt% and the developer cartridge 7 filled so as to be 30 wt% are left for two days, FIG. 6 is a diagram showing the distribution state of the carrier C in the developer cartridge 7. The developer cartridge 7 was roughly divided into the vicinity of the upper part (U), the vicinity of the center part (M), and the vicinity of the lower part (B), and the respective samples were taken out, and the local carrier weight ratio was measured.
According to the figure, although there is a slight difference in weight ratio (wt%) depending on the vertical position of the developer cartridge 7, the carrier weight ratio is substantially the same, and the carrier dispersion state is the toner. It can be seen that the sinking phenomenon of the carrier C that causes a non-uniform state that causes a defect such as a density defect does not occur.

An outline of a method for obtaining the weight ratio of the carrier C, or conversely, the weight ratio of the toner (toner concentration) will be described.
In the present embodiment, a blow-off measuring device (MODEL 210HS-2A) manufactured by TREK was used. With this apparatus, the average charge amount of the toner can be measured simultaneously with the toner concentration.
A sample developer is put in a case in which the carrier C is captured and the opening is covered with a mesh that allows only the toner T to pass through, and the weight of the developer is measured in advance with an electronic balance or the like.
The toner T and the carrier C are separated by suction by a suction pump, and the charge amount q of the toner captured by the Faraday gauge through the mesh is measured and calculated.
The increased weight of the Faraday gauge is measured to calculate the captured toner weight, and the toner concentration Tc is calculated from the percentage with respect to the developer weight before the start of measurement. The average charge amount q / m is calculated from the ratio of the toner charge amount q to the toner weight m.

FIG. 4 is a diagram illustrating a change in the weight ratio of the carrier as the number of toner replenishments increases.
This figure shows the change in the carrier weight ratio due to the difference in the number of replenishments by changing the carrier weight ratio into four types of 0, 10, 20, and 30 wt%. If the toner T is excessively discharged, the weight ratio of the carrier C is increased, and if the carrier C is excessively discharged, the weight ratio of the carrier C is decreased. Overall, it can be seen that the carrier weight ratio has hardly changed.
In the case of the developer cartridge 7 adopting a flexible material that can be deformed on part or all of the surface constituting the developer accommodating portion, the accommodating portion itself is caused by a suction action for discharging the accommodated developer. Since the volume of the container is deformed and deflated, there is almost no agitation operation in the container, and the weight ratio wt% of the carrier does not change much from the initially filled state as shown in FIG. Is replenished.

FIG. 5 is a diagram for explaining a problem due to a difference in porosity.
In the figure, G0 is a curve showing the fluctuation of the replenishment toner when the void ratio is 0%, and G1 is a fluctuation when the void ratio is sufficient.
In the volume-reduction type developer replenishment method, the developer 8 is discharged while the air in the gap in the upper layer portion of the storage portion is gradually discharged. In the case of the volume-reducing developer cartridge, it has been found at the time of the examination of the present invention that when the porosity is 0%, a packing phenomenon in which the developer is not discharged by the external air pressure occurs like a vacuum pack. Due to such a packing phenomenon, the developer does not move at all in the storage portion. Here, the volume ratio of the space above the upper surface of the developer with respect to the entire volume of the developer cartridge is referred to as the porosity. If there is a porosity of 12% or more, it can be discharged stably until the developer runs out.
Further, by setting the carrier weight ratio to 3 wt% or more, a carrier having a higher fluidity than the toner is mixed in a certain amount or more in the developer. As a result, the carrier and the surrounding toner are easily transported to the vicinity of the outlet inside the developer cartridge 7. Further, since the carrier in the developer also acts as a lubricant, the adhesion between the toners is lost, the toner moves smoothly, and the toner can be moved even with a smaller gap amount. Therefore, the developer 8 can be stably carried out even when the volume of the storage portion is reduced. On the other hand, if the carrier weight ratio is 30% or more, the developer is agglomerated in the vicinity of the developer discharge port and the fluidity is reduced, and the developer cannot be supplied stably.

  The above-described effects in carrying out the developer employing the carrier weight ratio can be achieved regardless of the presence or absence of additives in the toner. However, in order to further improve the fluidity, it is preferable to previously knead a lubricant having a ratio of the addition amount to the toner weight of 0.3 to 3.0 wt% in the toner. As the lubricant, for example, particles containing silica or titanium can be employed. These serve as spacers for the aggregation of the toners, and as a result, the fluidity can be improved.

The fluidity can be expressed as an accelerated aggregation degree. Then, the measuring method of the acceleration aggregation degree in embodiment of this invention is demonstrated. As a configuration of the measuring instrument,
(1) Powder tester (manufactured by Hosokawa Micron)
(Parts) Sieve presser, Space ring, Fixed chute, Vibro chute, Presser bar (2) Sieve (3 types) (Condition 1)
(3) It is a digital precision pan balance.

  Next, the measurement procedure is shown in Table 1. Measure according to the procedure from section No. 1 to 7 in Table 1.

In the calculation of the accelerated aggregation degree in the present invention, the aggregation degree can be obtained by the following calculation formulas (a) to (c).
(A) ((powder weight remaining on upper sieve) / (sampled amount)) × 100
(B) ((powder weight remaining on middle screen) / (sampled amount)) × 100 × 3/5
(C) ((powder weight remaining on the lower sieve) / (sample amount)) × 100 × 1/5
The total of the above three calculated values is defined as the degree of aggregation (%).

  Table 2 shows a list of measurement conditions in the present invention.

  If the measurement result is 10% or less, stable replenishability can be maintained regardless of the additive formulation, toner material and charging characteristics.

FIG. 6 is a view showing an image forming apparatus of the present invention.
In the figure, reference numeral 11 is a photosensitive member 12 is a charging charger, 13 is a writing unit, 14 is a developing unit, 15 is a primary transfer roller, 16 is a photosensitive member cleaning unit, 17 is a static elimination lamp (QL), 18 is an intermediate transfer belt, 20 is an intermediate transfer belt cleaning unit, 21 is a secondary transfer roller, 22 is a fixing unit, 23 is a paper discharge tray, 24 is a registration roller, 25 is a switchback roller, 26 and 27 are paper feed rollers, and 28 is a pickup roller. , 29 are paper feed trays, and L is writing light.
The development system adopts a dry two-component development system, and the system is a full color machine of a quadruple tandem type intermediate transfer system. However, this is given as a representative example of an image forming apparatus, and any other configuration or method is not limited as long as it is a dry two-component development method.
First, an image forming operation will be described. When a print start command is input, the rollers around the photosensitive member 11 as the latent image carrier, around the intermediate transfer belt 18 and the paper feeding / conveying path start to rotate and from the lower paper feeding tray 29 to the recording paper Sheet feeding starts. The surface of each photoconductor 11 is charged to a uniform potential by a charging charger 12 as a charging unit, and the surface is exposed according to image data by writing light L emitted from a writing unit 13 as an exposure unit. .

The potential pattern after the exposure is called an electrostatic latent image. The photosensitive member 11 carrying the electrostatic latent image on the surface thereof is supported by supplying toner in a dry two-component developing unit 14. The electrostatic latent image is developed to a specific color. In the figure, since there are four photosensitive members 11, toner images of yellow, magenta, cyan, and black (color order varies depending on the system) are developed on each photosensitive member 11. The toner image developed on the photoconductor 11 is transferred to a primary transfer roller 15 as a transfer unit disposed opposite to the photoconductor 11 at a contact point with the intermediate transfer belt 18 by a transfer bias and a pressing force. The image is transferred onto the intermediate transfer belt 18. By repeating this for the four colors while matching the timing, a full-color toner image is formed on the intermediate transfer belt 18 as an image carrier.
The full-color toner image formed on the intermediate transfer belt 18 is transferred to the recording paper conveyed by the registration roller 24 in time. At this time, transfer is performed by a secondary transfer bias applied by the secondary transfer roller 21 and a pressing force. The recording paper to which the full color toner image has been transferred passes through the fixing unit 22, whereby the toner image carried on the surface is heated and fixed.

  If it is single-sided printing, it is conveyed straight as it is to the paper discharge tray 23, and if it is double-sided printing, the conveyance direction is changed downward and conveyed to the paper reversing unit. The recording paper that has reached the paper reversing section is reversed in the transport direction by the switchback roller 25 and exits the paper reversing section from the rear end of the paper. By this operation, the front and back of the recording paper can be reversed. The recording paper that is turned upside down does not return to the fixing unit 22 but passes through the refeeding path and joins the original feeding path. Thereafter, the toner image is transferred in the same manner as the front surface printing, and is discharged through the fixing unit 22. This is a double-sided printing operation. The operation of each part will be described to the last. The photoreceptor 11 that has passed through the primary transfer part carries the primary transfer residual toner on the surface thereof, and this is removed by the photoreceptor cleaning unit 16. Thereafter, the surface is uniformly discharged by a QL (quenching lamp) 17 to prepare for charging for the next image. Further, the intermediate transfer belt 18 that has passed through the secondary transfer portion also carries secondary transfer residual toner on the surface thereof, but this is also removed by the intermediate transfer belt cleaning unit 20 so that the next toner image Prepare for transcription. By repeating such an operation, single-sided printing or double-sided printing is performed.

FIG. 7 is a schematic diagram for explaining changes due to vibration of the developer 8 accommodated in the developer cartridge. FIG. 5A shows a state in which the initial carriers are dispersed, and FIG. 6B shows a state in which repeated vibrations are received.
FIG. 8 is a schematic diagram showing a developer 8 accommodated in a developer cartridge according to another embodiment of the present invention.
In both figures, symbol C indicates a carrier, and T indicates a toner.
Even if the developer cartridge 8 is simply filled in the developer cartridge, as described above, in the configuration of the present invention, there is almost no stirring operation during actual use. Therefore, as shown in FIG. Although there is relatively no possibility of sinking, there is a possibility that the developer cartridge is repeatedly vibrated with movement such as transportation after being filled with the developer 8 and before being used by the user. In such a case, there is still a possibility that the carrier C sinks toward the bottom due to the difference in specific gravity, as shown in FIG.
Therefore, in another embodiment of the present invention, the developer 8 composed of the toner T and the carrier C is sufficiently charged before filling, and then mixed so that the carrier C is dispersed. In this state, as shown in FIG. 8, the carrier is positively charged and the toner is negatively charged and attracts each other by Coulomb force, so that the sinking action of the carrier can be suppressed.
However, if the developer 8 that has been charged is left to stand for a long period of time, the charge of the toner and carrier gradually disappears due to the charge neutralization that occurs naturally, and can approach a non-charged state. There is sex. This tendency is particularly remarkable when the developer 8 is not sufficiently dried. Therefore, in the embodiment of the present invention, when the developer cartridge 7 is filled with the developer 8, consideration is given in particular to avoid mixing water into the developer 8. Further, in order to prevent the humidity of the developer 8 from increasing in the storage state, a material having a particularly low water vapor transmission rate is used for the configuration of the developer cartridge (details will be described later).

The charge amount of the toner in the developer 8 is approximately equal to the charge amount when the carrier C is supplied to the developing device 10 and mixed with the developer contained therein, and then charged by stirring with an internal screw or the like. The charging action is exerted on the developer 8 so as to be more than that. The details of the same amount of charge will be described. The developer 8 and the encapsulated developer cannot be simply compared because their carrier weight ratios are greatly different. Therefore, the same amount of charge means the average charge amount of the encapsulated developer when the developer 8 maintains the average charge amount and the weight ratio of the carrier is increased to about the encapsulated developer. It means to be about -30 μC / g.
After stirring and charging as described above, the developer cartridge 7 is filled with the developer 8 so that the carrier C and the toner T around the carrier C attract each other, so that the carrier in the developer cartridge is attracted to each other. Sinking can be suppressed, and when the developer 8 is supplied to the developing device 10, at least the toner has already been charged to the same level as or higher than the amount of charge to be stirred and charged in the developing device. Ground contamination and toner scattering due to insufficient charging of toner can be suppressed.
Further, even if the toner is sufficiently charged before filling, there is a possibility that the carrier and the toner are neutralized by the filling action, and as a result, the carrier sinks in the developer cartridge. Therefore, by setting the filling process so that the developer 8 is charged while being frictionally charged, the sinking of the carrier can be suppressed and the ground due to insufficient charging of the toner when the carrier is supplied to the developing device 10. Dirt and toner scattering can be suppressed.

Generally, the charge amount by frictional charging due to contact between the toner and the carrier by stirring and conveying in the developing device is up to the maximum chargeable amount in the developer 8 including the toner and the carrier (this is referred to as a saturation charge amount for convenience). It has not reached. In many cases, the charge amount during normal use is about 50 to 80% of the saturation charge amount. For example, when the saturation charge amount is −40 μC / g, the average charge amount of the toner is about −20 to −30 μC / g in the actual use state (charging in the developing device).
The charge amount of the toner in the developer cartridge of the present invention is to be as close to the saturated charge amount as possible. It is preferable to charge about 50% or more of the saturation charge amount, more preferably about 80% or more. In the above example, the average charge amount of the toner in the developer stored in the developer cartridge is at least −20 μC / g, preferably −30 μC / g.

As a material for the developer cartridge, a material having a water vapor transmission rate per 24 hours of 1.0 g / m ² or less is preferably used. All of the water vapor transmission rates in this example are planned to be measured by the JIS K 7126 A method (differential pressure method) including those described below. With such a material, it is possible to suppress the non-charging effect of the developer due to moisture absorption during transportation and storage after the developer cartridge 8 is filled in the developer cartridge. Therefore, since the state in which the carrier C and the toner T are sufficiently charged at the time of filling is maintained, the sinking of the carrier C in the developer cartridge can be suppressed, and the developer 8 is supplied to the developing device. Occasionally, the dirt and toner scattering due to insufficient charging of the toner T can be suppressed. In the embodiment, a developer cartridge 7 is used in which a material composed of a film having a three-layer structure of polyethylene, nylon, and PET is used for the entire storage portion.

Since there is a similar problem (moisture absorption) in the developer conveyance path, it is necessary to use a material having a low water vapor transmission rate as the material of the flexible tube 6. Otherwise, in the actual use state, the toner T absorbs moisture before reaching the developing device 10 and the charge is escaped, so that the carrier C is affected by gravity and may sink in the tube. .
Therefore, by using a material having a water vapor transmission rate of 1.0 g / m ² or less per 24 hours for the developer conveying path, when the developer 8 is supplied from the developer cartridge to the developing device, the developer 8 absorbs moisture. Can be suppressed.
Therefore, since the state in which the carrier C and the toner T are sufficiently charged at the time of filling is maintained, the sinking of the carrier in the developer 8 conveyance path can be suppressed, and the carrier C is supplied to the developing device 9. In this case, it is possible to suppress background contamination and toner scattering due to insufficient charging of the toner T. In the embodiment, a silicon rubber tube is used. In addition, fluorine rubber, EPDM, polyurethane rubber, or the like can be used.

FIG. 9 is a diagram for explaining a process of filling the developer cartridge with the developer 8.
In the figure, reference numeral 200 is a filling device, 102 is a gas-powder separation sieve comprising a breathable porous plate, 103 is an air header, 107 is an air compression pipe, 110 is a stirring vessel, 111 is a powder inlet, and 112 is a flow Powder transport pipe, 113 is a pressure release valve, 114 is a pressure gauge, 115 is a powder flow rate adjusting valve, 116 is a gas-powder separation sieve, 117 is a filling nozzle, 118 is a powder container, 119 is a soft packing, Reference numeral 120 denotes an introduction gas control valve, 124 denotes a powder outlet pipe, 125 denotes a first pressure reducing valve, 126 denotes a second pressure reducing valve, 127 denotes an air flow meter, and P1 to P3 denote first to third pressure gauges, respectively.
Here, a charging method before replenishing the developer 8 to the developer cartridge 7 which is a main part of the embodiment of the present invention will be described.
For charging, a device called Turbula Shaker Mixer manufactured by Shinmaru Enterprises was used.
First, a target amount of toner, for example, 500 g is weighed out and put into the stirring container 110 from the powder inlet 11. Next, a desired amount of the carrier amounts 16 g to 125 g at which the weight ratio corresponding to the total amount including the toner amount is 3 to 20 wt% is measured, and the mixture is similarly added to the toner.
When the above mixture is mixed for 60 seconds with strong stirring by a turbula mixer, a charging action substantially corresponding to the charge amount of the toner described above can be produced. This is designated as Developer 8. Thereafter, the developer cartridge is filled using an air flow.

  High-pressure air is sent into the air header 103 through the first pressure reducing valve 125, the second pressure valve 126, and the like connected to a compressed air source (not shown). The high-pressure air blows the developer in the stirring vessel 110 toward the 110a through the gas-powder separation sieve. By this pressure, the developer reaches the filling nozzle 117 through the powder outlet tube 124 and the fluidized powder transport tube 112. When the developer fed by the high-pressure air enters the powder container 118, only the high-pressure air goes out of the powder container 118 through the gas-powder separation sieve 116. In this way, the developer 8 is left and accumulated in the powder container 118. When the powder container 118 is the developer cartridge 7, only the filling nozzle 117 is inserted in a state where it is almost folded before filling is started. The air inserted along with the filling of the developer 8 escapes from the container through the gas-powder separation sieve 116 and gradually expands the developer cartridge 7. When the maximum volume is reached, the filling is temporarily stopped, air is released to reach a predetermined gap amount, or a small amount of additional filling is performed to adjust the gap amount, and then the necessary sealing work is performed and the process is terminated. In addition to the gas-powder separation sieve 116, a straw-shaped exhaust pipe capable of positively releasing air is attached to the developer cartridge 7 so that more air can be discharged and filled to facilitate adjustment. You can also If the operation is stable, it is possible to efficiently fill a predetermined gap amount without exhausting after the filling is stopped or filling again.

When the developer supply system is configured to supply the developer 8 to the developing device through the flexible tube 6, the developer 8 is sucked from the developer cartridge 7 using the powder pump 4. It has been found that when the developer cartridge 7 is 100% filled with the developer 8, as described above, the packing phenomenon occurs and the supply cannot be performed well. Therefore, it is preferable to reduce the filling amount of the developer 8 and fill the air by the vacant amount.
After the developer 8 is filled, the space above the developer 8 is filled with gas so that the developer cartridge has a maximum volume (a volume when water is filled). The porosity can be calculated as (maximum volume−developer volume) / maximum volume × 100 (%).
After the filling, when the developer is left for at least 10 minutes, the developer fumes are generally settled, and the volume of the developer in the developer cartridge (the bottom area inside the storage container × the measured height) can be accurately measured.
Strictly speaking, the developer 8 has a gas (air) in a minute space between the toners, and a slight change occurs in the minute space due to the influence of gravity or the like for a while immediately after filling. Therefore, the volume of the developer 8 as a whole may slightly decrease. In the above, the reason for leaving after standing for 24 hours or more is to exclude such a volume change from the height measurement value for calculating the porosity. Ascertain the correlation between an arbitrary standing for 10 minutes or more and a standing for 24 hours or more in advance as a plurality of data, and as a guideline for mass production of a large amount of developer cartridge, it is calculated with 10 minutes or an arbitrary height It is better to substitute the values that have been set.

It is a figure for demonstrating a volume-reduction type toner replenishment system. FIG. 3 is a diagram illustrating a developer cartridge that is an embodiment of the present invention. It is a figure which shows the carrier distribution measurement result in STC at the time of leaving still in a stationary state. FIG. 6 is a diagram illustrating a change in the weight ratio of a carrier with an increase in the number of toner replenishments. It is a figure for demonstrating the problem by the difference in the porosity. 1 is a diagram showing an image forming apparatus of the present invention. FIG. 6 is a schematic diagram for explaining a change caused by vibration of the developer 8 accommodated in the developer cartridge. Schematic showing a developer 8 according to another embodiment of the present invention housed in a developer cartridge. FIG. 6 is a diagram for explaining a process of filling a developer cartridge with a developer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developer cartridge 2 Nozzle 3 Flexible tube 4 Powder pump 6 Sub hopper 9 Developing device C Carrier T Toner

Claims (13)

  A developer storage container for storing a developer containing toner and a carrier, wherein the developer storage container is connected to a suction type powder pump, and the developer is carried out by suction of the powder pump.   2. The developer storage container according to claim 1, wherein a part or all of a surface constituting the storage portion for storing the developer is made of a material having deformable flexibility. Agent storage container.   The developer storage container according to claim 1 or 2, wherein the developer is filled in the developer and allowed to stand for 24 hours or more in a stationary state, and the porosity in the developer container measured after the standing is 12%. A developer container characterized by the above.   4. The developer storage container according to claim 1, wherein a weight ratio of the carrier to the developer is 3 wt% to 20 wt%. 5.   5. The developer storage container according to claim 1, wherein a toner charge amount of the developer stored in the developer storage container is adjusted to be within a certain range. Storage container.   6. The developer storage container according to claim 5, wherein the adjustment is such that the toner charge amount of the developer stored therein is set to be equal to or greater than the toner charge amount of the internal developer contained in the developing device. A developer storage container.   7. The developer storage container according to claim 6, wherein the adjustment is applied by a frictional charging effect that occurs during a step of storing the developer in the storage portion in which all or a part of the toner charge amount in the developer is stored in the storage portion. A developer storage container.   8. The developer storage container according to claim 1, wherein the toner includes a lubricant having a weight ratio of 0.3 to 3.0 wt% with respect to the toner. container.   9. The developer storage container according to claim 7, wherein the developer has an accelerated aggregation degree of 10% or less. The developer storage container according to any one of claims 1 to 9, wherein the material has a water vapor transmission rate per 24 hours of 1.0 g / m ² or less.   The developer storage container according to any one of claims 1 to 10, the powder pump, and a developer transport path that communicates with the developer storage container and includes the powder pump as a part of the path. At least a developing device that replenishes the developer from the developer container through the developer transport path and discharges a part of the encapsulated developer contained in response to the replenishment to the outside of the apparatus. An image forming apparatus.   12. The image forming apparatus according to claim 11, wherein the developer transport path is configured using a tubular member made of a deformable flexible material.   13. The image forming apparatus according to claim 11, further comprising a hopper for storing the developer between the powder pump and the developing device.

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