JP2007133057A - Premixed toner supply device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a premixed toner supply device and an image forming apparatus simplifying maintenance while avoiding an increase in its scale and complication. <P>SOLUTION: Provided are the premixed toner supply device 101 which supplies premixed toner 8 obtained by dispersing toner and carrier at fixed density, has a container which is filled with the premixed toner 8 and whose shape is easily deformed, and a suction pump 4, and is used for a two-component electrophotographic system, and where the premixed toner 8 is sucked by the suction pump 4 and supplied to a developing device, and the image forming apparatus 100 having the premixed toner supply device 101. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner concentration control device for an electrophotographic apparatus using a two-component developer in an electrophotographic apparatus such as a copying machine, a fax machine, a printer, etc. It is related to the technology to supply to.

The developer filled in the two-component developer has the ability to charge the toner by the wear of the coat layer of the carrier surface layer as the image is output, or conversely, the toner resin or additive adheres to the coat layer. In the past, service personnel have regularly visited and exchanged users in order to gradually decrease and cause contamination of the background and toner scattering when the level falls below a certain level. For this reason, there is a problem in that maintenance cost is increased and the copy unit price becomes high.
In order to solve this problem, as disclosed in Patent Document 1, a trickle developing method has been proposed in which a carrier is automatically and periodically replenished separately from the replenishing toner. However, this method requires a space for storing a 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 Patent Document 2, a developer supply container having an opening for discharging the stored developer is provided so as to protrude at least from the inner wall of the container, and has a spiral shape toward the opening. A developer having a ridge and replenishing the developer conveyed by the ridge with the rotation of the developer supply container to the developer receiving device from the opening. A developer replenishing container containing 1 to 30 parts of toner with respect to 1 part of carrier and having a true specific gravity of 2.5 to 4.5 is disclosed. As a result, even when used for a long period of time, there is no toner scattering, the toner charge amount in the developing device is stable, the image enhancement uniformity and gradation are excellent, and a high-quality image without fogging can be obtained. A replenishment development unit is provided.

Patent Document 3 discloses a developer replenishment kit that is detachably attached to the image forming apparatus, a container that stores the developer, a discharge port that is provided in the container and discharges the developer, and the container. A flexible member that stirs the developer while rubbing the inner surface and conveys the developer to the discharge port, and the developer is composed of a mixture of toner and substantially spherical spacer particles, and the average of the spacer particles A developer replenishment kit is disclosed in which the particle size (D ₅₀ ) is larger than the weight average particle size (D ₄ ) of the toner. 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 added to the replenishment toner of a bottle cartridge that rotates and supplies toner (see FIG. 1).
However, in this system, the toner and the carrier are separated, and only the carrier is concentrated before or after the supply, so that 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. In any of the inventions, since the toner and the carrier are limited, the cost is increased. Furthermore, since the carrier filling amount is large, the cost of consumables (toner carrier) increases. In addition, the environment was deteriorated in order to destroy many carriers.

  On the other hand, a volume-reducing toner replenishing system (see FIG. 2) in which a container such as vinyl is easily deformed (hereinafter referred to as STC) is filled with toner, and the toner is sucked with a Mono pump or the like to replenish the toner to the developing device. ) Has a problem that the toner cannot be replenished stably unless the gap in the STC is sufficient (see FIG. 3). In addition, when the gap is increased, the amount of toner is reduced or the container is increased, resulting in an increase in the size of the apparatus.

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

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and its object is to provide a premix toner supply device and an image forming apparatus that avoid the increase in size and complexity of the apparatus and simplify the maintenance of the apparatus. It is to be.

The features of the present invention, which is a means for solving the above problems, are listed below.
The present invention provides a premix toner supply device that supplies a premix toner in which a toner and a carrier are dispersed at a constant concentration, and includes a container that is filled with the premix toner and is easily deformed, and a suction pump. The premix toner supply device is a premix toner supply device which is used in a two-component electrophotographic system and sucks the premix toner with the suction pump and supplies it to a developing device. As a result, there is no toner stirring operation in the toner cartridge, and there is no stirring operation, and the toner is always replenished in a constant state.

According to the present invention, in the premix toner supply device described above, the premix toner supply device has a porosity of 12% or more in a state where the premix toner is left standing for 24 hours. The premix toner supply device. Thus, since the toner is not packed like a vacuum pack, the toner can be discharged from the STC stably at a constant amount with a uniform density.
The present invention is the premix toner supply apparatus described above, wherein the premix toner supply apparatus has a carrier to toner weight ratio of 3 wt% to 20 wt%. As a result, the specific gravity of the toner increases and the carrier also acts as a lubricant, so that the rushed toner flows smoothly, so that a constant amount of toner can be stably supplied at a uniform concentration.

The present invention is the premix toner supply device described above, wherein the premix toner supply device has a lubricant addition amount of 0.3 to 3.0 wt% to the premix toner used in the premix toner supply device. The premix toner supply device according to claim 1. Thereby, since fluidity | liquidity can be maintained, a predetermined amount can be stably supplied with a uniform amount and a premix toner can be supplied.
The present invention is the premix toner supply device described above, wherein the premix toner supply device uses a premix toner having an accelerated aggregation degree of 10% or less of the premix toner used in the premix toner supply device. The premix toner supply device. As a result, it is possible to stably supply a premixed toner in a constant amount with a uniform concentration regardless of the additive formulation, toner material, and charging characteristics.

The present invention is an image forming apparatus using the premix toner supply device described above. Thereby, since a constant amount of premix toner having a constant density is always supplied, the occurrence of abnormal images can be suppressed.

According to the present invention, it is possible to provide a premix toner supply device and an image forming apparatus which can avoid the increase in size and complexity of the apparatus and simplify the maintenance of the apparatus by means for solving the above problems.

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. 2 is a view showing an outline of a premix toner supply device of a volume reduction type toner replenishment method. A premixed toner 8 mixed with a carrier is filled in a toner cartridge (hereinafter referred to as STC) having a shape in which the material is soft and the shape is folded to reduce the volume. The STC is provided with a toner discharge port connected to the lowermost portion by the nozzle 9, and the premixed toner filled in the STC is dropped by its own weight and collected at the discharge port. When it is determined from the output of a toner density sensor installed in a developing device (not shown) that the toner density in the developing device is low, the suction type powder pump 4 is driven (in the embodiment, the clutch is connected and the pump rotates). To do). By driving the pump, the premix toner is sucked into the powder pump through the tube 6 connecting the nozzle and the pump. In the illustration, the sub hopper 2 is installed, and at the same time, the conveying screw of the sub hopper 2 is driven to supply toner from the sub hopper 2 to the developing device. However, in the present invention, the sub hopper 2 may be omitted and the toner may be supplied directly from the pump to the developing device. When the required amount of premix toner is supplied to the developing device, the driving of the powder pump is stopped (in the embodiment, the clutch is disengaged), and the toner supply is stopped.

In the conventional replenishment method, the toner is transported to the bottle outlet while being stirred inside the bottle by replenishing the toner and carrier mixed toner from the bottle with a spiral groove cut in the bottle. The carrier sinks to the bottom and is preferentially transported along the groove to the outlet. Therefore, the carrier is selectively replenished first, the toner density control in the developing unit becomes unstable, and an abnormal image is generated. In the present invention, since it is a volume-reduced STC toner cartridge, there is no toner stirring operation in the toner cartridge. For this reason, the premix toner once uniformly mixed before filling does not separate while the toner and the carrier are uniformly dispersed.
FIG. 4 shows the carrier distribution measurement results in the STC when left in a stationary state. FIG. 5 shows the change in carrier wt% in the replenishing toner. In the case of STC, since the container itself is deformed and squeezed when the toner is discharged, there is no agitation operation in the STC, and the toner is replenished while the wt% of the carrier is always constant as shown in FIG. .

In the volume reduction type toner replenishment method, the toner is discharged while gradually discharging the air in the gap in the STC upper layer. In the case of the volume reduction type STC, when the void ratio is 0%, the toner is packed like a vacuum pack, and the toner does not move at all in the STC. When the porosity is 12% or more, the toner can be stably discharged from the STC until the toner runs out.
Further, when the carrier weight ratio is 3 wt% or more, the specific gravity of the toner increases, and the toner easily rushes near the outlet inside the STC. Furthermore, since the added carrier also acts as a lubricant, the rushed toner flows smoothly, so that the toner can be supplied with a smaller amount of voids. Therefore, the toner can be stably replenished with the STC volume reduced. On the other hand, if the carrier specific gravity is 30% or more, the fluidity is lowered, and the toner cannot be supplied stably.

When the premix toner of the present invention is used, fluidity can be maintained even if the addition amount is small. However, in order to further maintain fluidity, it is preferable to add a lubricant to the premix toner having an addition amount of 0.3 to 3.0 wt%. As a lubricant to be added to the premix toner, for example, Si or Ti is added in order to give the toner fluidity.

The fluidity can be expressed as an accelerated aggregation degree. Then, the measuring method of the acceleration aggregation degree in 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 it is 10% or less as a result of measurement by the above measurement method, stable replenishability can be maintained regardless of the additive formulation, toner material and charging characteristics.

FIG. 6 is a diagram showing an image forming apparatus of the present invention. 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 means, and the surface is exposed according to image data by writing light emitted from a writing unit 13 as an exposure means. .

The potential pattern after exposure is called an electrostatic latent image. The photosensitive member 11 carrying the electrostatic latent image on the surface thereof is carried by supplying toner in a dry two-component developing unit. The electrostatic latent image is developed to a specific color. In FIG. 6, 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 photoreceptor 11 is intermediated by a transfer bias and a pressing force applied to a primary transfer roller 15 serving as a transfer unit disposed opposite to the photoreceptor 11 at a contact point with the intermediate transfer belt 20. The image is transferred onto the transfer belt 20. By repeating this for the four colors while matching the timing, a full-color toner image is formed on the intermediate transfer belt 20 as an image carrier.
The full-color toner image formed on the intermediate transfer belt 20 is transferred onto the recording paper conveyed by the registration roller 24 in time. At this time, transfer is performed by the secondary transfer bias applied by the secondary transfer roller 21 and the 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. The intermediate transfer belt 18 that has passed through the secondary transfer portion also carries secondary transfer residual toner on its surface, which is also removed by the intermediate transfer belt cleaning unit to transfer the next toner image. Prepare for. By repeating such an operation, single-sided printing or double-sided printing is performed.

FIG. 5 is a diagram illustrating a method in which a developer is added to replenishment toner of a bottle cartridge that rotates and supplies toner. FIG. 3 is a diagram illustrating an outline of a premix toner supply device of a volume reduction type toner replenishment method. It is a figure which shows the change of the replenishment toner mass by the difference in STC space | gap capacity | capacitance. It is a figure which shows the carrier distribution measurement result in STC at the time of leaving still in a stationary state. It is a figure which shows the carrier wt% change in replenishment toner. 1 is a diagram showing an image forming apparatus of the present invention.

Explanation of symbols

1 MONO clutch 2 Sub hopper 3 Sub hopper crunch 4 Suction type powder pump 5 TE sensor (toner remaining amount detection sensor)
6 Flexible tube 7 Toner container 8 Premix toner 9 Nozzle 10 Developing unit 11 Photoconductor 12 Charging charger 13 Writing unit 15 Primary transfer roller 16 Photoconductor cleaning unit 17 QL (quenching lamp)
18 Intermediate transfer belt 20 Intermediate transfer belt 21 Secondary transfer roller 22 Fixing unit 23 Paper discharge tray 24 Registration roller 25 Switchback roller 29 Paper feed tray 35 Chuck 36 Gap 37 Set lever 38 Bottle drive motor 39 PCU
40 PCU protrusion 41 Shutter 42 Toner bottle 100 Image forming apparatus 101 Premix toner supply device

Claims (6)

Supply premix toner in which toner and carrier are dispersed at a constant concentration,
A container filled with the premixed toner and having a shape easily deformed;
A suction pump;
In a premix toner supply device having
The premix toner supply device is used for a two-component electrophotographic system,
The premix toner supply device, wherein the premix toner is sucked by the suction pump and supplied to the developing device. The premix toner supply device according to claim 1,
The premix toner supply device, wherein the premix toner supply device has a porosity of 12% or more in a state where the premix toner is left standing for 24 hours. The premix toner supply device according to claim 2,
The premix toner supply device, wherein the weight ratio of the carrier to the toner is 3 wt% to 20 wt%. The premix toner supply device according to claim 3.
In the premix toner supply device, the amount of lubricant added to the premix toner used in the premix toner supply device is 0.3 to 3.0 wt%. The premix toner supply device according to claim 3.
The premix toner supply apparatus, wherein the premix toner supply apparatus uses a premix toner having an accelerated aggregation degree of 10% or less of the premix toner used in the premix toner supply apparatus. An image forming apparatus using the premix toner supply device according to any one of claims 1 to 5.

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