JPH0429271A - Developer feeding discharging mechanism - Google Patents

Abstract

PURPOSE:To shorten the handling time of a developer exchanging work and to simultaneously obtain stable printing quality without being affected by the life of a developer by discharging the developer of a prescribed quantity set in advance and supplying the fresh developer of the almost same quantity as a discharging quantity, when the used quantity of the developer inside a developing machine reaches a value set in advance. CONSTITUTION:The developer discharging part of the developing machine 1 is communicated with a developer container by a discharging pipe 8 via a discharging valve 7. When the used quantity of the developer 2 reaches the value set in advance, a part of the developer 2 finished to be used is exhausted by the prescribed quantity set in advance, the fresh developer 4 of almost the same quantity as the discharging quantity is fed to the developing machine 1 from a housing tank 3. In other words, the developer 2 is automatically and continuously discharged little by little and the fresh developer 4 of the same quantity is fed little by little, before the developer 2 inside the developing machine 1 is degraded in its quality reacher its service life. Thus, a period for carrying out the exchanging work of the developer 2 is prolonged, and simultaneously, the printing quality can be always stabilized.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a developer supply and discharge mechanism for supplying and discharging the developer in a developing machine of an electrophotographic printing machine using a dry two-component developer. Regarding.

[Conventional technology]

In a developing machine of an electrophotographic printing machine using a dry two-component developer, maintenance personnel or operators have conventionally performed the work of discharging the developer that has reached the end of its life and supplying new developer.

The contents of this work are usually to collect the expired developer into the empty container that contained the developer, and then to supply new developer from the input port of the developing machine.

Incidentally, the amount of developer filled in the developer container is usually the same amount as the amount of developer in the developing machine.

Therefore, the developer in the developing machine must be replaced every time the developer reaches the end of its service life.

[Problem to be solved by the invention]

However, in the above-mentioned conventional technology, when a printer that prints a large amount is used as a printer, there is a drawback that the developer replacement cycle becomes short.

Further, as printers become smaller and lighter, developing machines themselves are required to be smaller, and as a result, the developer capacity within the developing machine is also reduced to a walking capacity, which has the disadvantage of further shortening the developer replacement cycle.

In addition to this, as the developer gradually approaches the end of its life due to long-term use, the print quality also deteriorates.

Therefore, printing quality can be restored again by replacing the developer that has reached the end of its service life, but there is a large difference in print quality between the developer that has reached the end of its life and the new developer, and as a result, the print quality is lower than that of the developer. This had the disadvantage that it changed significantly over the life cycle.

It is an object of the present invention to provide a developer supply and discharge system that eliminates the drawbacks of the prior art described above, reduces the effort that maintenance personnel or operators spend on developer replacement work, and provides stable printing quality that is not affected by the lifespan of the developer. The goal is to provide a mechanism.

[Means to solve the problem]

The purpose is to remove all of the used developer in the developing machine when the amount of developer used in the developing machine reaches a preset value in the developing column of an electrophotographic printing machine that uses a dry two-component developer. This is achieved by providing a means for discharging a predetermined amount of developer, and a means for supplying a new developer to the developing machine in an amount substantially equal to the discharged amount.

[Effect]

That is, the present invention automatically and continuously discharges a small amount of the developer in the developing machine and supplies the same amount of new developer in small amounts before the developer in the developing machine becomes fatigued as printing is performed and reaches the end of its service life. [Example] The present invention will be explained below based on the drawings. 1 is an explanatory diagram of the overall configuration of an embodiment of a developer feeding mechanism according to the invention; FIG.

In FIG. 1, numeral 1 indicates a developing machine, and the developing machine 1 contains a developer 2 involved in printing. A new, unused developer 4 is stored in the storage tank 3. The storage tank 3 is arranged at a higher position than the developing machine 1. The internal capacity of the storage tank 3 is larger than the internal capacity of the developing machine 1, and the developing machine 1 and the storage tank 3 are connected by a supply vibro via a supply valve 5 that controls opening and opening of the supply of new developer 4. . A developer discharge portion of the developing machine 1 is provided with a discharge valve 7,
A developer container 9 is connected by a discharge pipe 8. The developer container 9 is arranged at a lower position than the developer ll11, and can store the same amount of developer as the storage tank 3. A level sensor 10 for detecting the amount of developer 2 is provided inside the developing machine 1 .

The lifespan of the developer 2 is limited by the fact that the toner adheres to the carrier made of magnetic powder such as iron powder or ferrite and covers the surface, resulting in an increase in electrical resistance, or a decrease in the amount of charge due to frictional charging. The spent amount, which is the ratio of the weight of toner attached to the carrier to the weight of the carrier, is used as a measure of this lifespan.

FIG. 2 is a characteristic diagram showing the relationship between the number of printed pages and the spent amount, which is a measure of developer life.

A curve 11 shown by a one-dot chain line in FIG. 2 shows an increase in the amount of spent developer in a conventional developing machine, and the developer is replaced every time the number of pages printed is increased.

On the other hand, according to the present invention, as shown by the curve 12 shown by the solid line in FIG. 2, in the case of completely new developer, the number of printed pages T
Until then, the spent amount increases as printing progresses and reaches A, as in the conventional case, but after that, the discharge valve 7 is opened and the amount of developer 2 in the developing machine 1 is monitored with a level sensor. Discharge approximately 20 to 30% of the developer into the developer container 9, close the discharge valve 7, then open the supply valve 5, check the amount of developer 2 with the level sensor 10, and replenish the developer 4 by putting a predetermined amount into the developing machine 1. However, by closing the supply valve 5, the spent amount decreases to B by about 20 to 30%. Note that there is a correlation between the amount spent and the number of printed pages, and when the number of printed pages reaches P, the amount spent again reaches A, so here, the developer 2 in the developing machine 1 is Similarly, approximately 20 to 30% of the developer is discharged into the developer container 9, and the same amount of the new developer 4 in the storage tank 3 is refilled into the developing machine 1. By performing this series of operations for each number of printed pages P, the spent amount of the 1 gA developer 2 can always be maintained between B and A. Note that the series of operations of discharging the developer 2 and supplying the new developer 4 are performed when the predetermined number of printed pages T or P is reached.
Alternatively, if P has been reached, it is sufficient to discharge the developer 2 and supply new developer 4 when printing stops or when the printer is powered on and warmed up, and the storage tank 4 is When the storage tank 4 is empty, a maintenance person or an operator can put new developer into the storage tank 4 and replace the empty container with the developer container 9.

Note that the storage tank 3 for the developer 4 in the above embodiment is as follows:
The deviation may be 5N when forming part of the printer body or forming part of the developer container 9.

Furthermore, in the above embodiment, the usage amount of the developer 2 is counted by the number of printed pages and considered as the developer supply/discharge timing. Even when counting , the same effect as in the above embodiment can be obtained.

Further, in the above embodiment, the case where the amount of developer discharged and supplied is about 20 to 30% has been exemplified. Furthermore, if the amount is reduced to a level that does not adversely affect the charging state, a series of discharge and supply operations can be performed even during printing operations.

〔Effect of the invention〕

The present invention is as described above, and as is clear from the description of the illustrated embodiment, according to the present invention, maintenance personnel or operators can perform developer replacement work even in small-sized developing machines and printers that print a large amount. This can lengthen the cycle and reduce machine downtime. In addition, the developer supply/discharge mechanism reduces the number of times developer is handled, which can easily stain clothes or hands, and stabilizes developer fatigue (spent amount), ensuring stable print quality at all times. can be obtained.

In addition, as shown in the above embodiment, the volume of the tank 3 storing the new developer 4 with respect to the developer storage volume of the developing machine 1,
Furthermore, the volume of the container 9 that stores approximately the same amount of used developer 2 as the new developer 4 supplied from the storage tank 3 to the developing machine 1 is determined as the capacity of the container 9 for storing the developer of the developing machine 1. If it is made larger than the volume, the replacement cycle of the new developer 4 and the used developer 2 can be further extended.

[Brief explanation of the drawing]

Fig. 1 is an explanatory view of the overall configuration of an embodiment of the developer supply/discharge mechanism according to the present invention, and Fig. 2 is a characteristic diagram showing the relationship between the number of printed pages and the amount spent, which is a guideline for the life of the current fjNPJ. be. 1 is a developing machine, 2 is a developer, 3 is a storage tank, 4 is a new developer, 5 is a supply valve, 6 is a supply pipe 7 is a discharge valve, 8 is a discharge pipe, 9 is a developer container, 10 is a level sensor .

Claims (1)

[Claims] 1. In a developing machine of an electrophotographic printing machine that uses a dry two-component developer, when the amount of developer used in the developing machine reaches a preset value, the used developer in the developing machine is A developer supply/discharge mechanism comprising means for discharging a predetermined amount of a portion of the developer, and means for supplying a new developer in an amount substantially equal to the discharged amount to a developing machine. 2. The amount of developer used in the developing machine is counted by the number of printed sheets, and when the number of printed sheets reaches a preset number, a part of the used developer in the developing machine is 2. A developer supply/discharge mechanism according to claim 1, comprising means for discharging a predetermined amount of developer, and means for supplying a developing machine with approximately the same amount of new developer as the discharged amount. 3. Count the amount of developer used in the developing machine based on the operating time of the developing machine, and when that time reaches a preset time, remove some of the used developer in the developing machine in advance. 2. A developer supply/discharge mechanism according to claim 1, comprising means for discharging a predetermined amount of developer, and means for supplying a new developer to a developing machine in an amount substantially equal to the discharged amount. 4. The capacity of the tank for storing new developer relative to the developer storage capacity of the developer rail, and the amount of used developer that is approximately the same as the new developer supplied from the storage tank to the developing machine. Claims 1 to 3 are characterized in that the volume of the container for discharging and accommodating is larger than the developer storage capacity of the developing machine.
The developer supply/discharge mechanism according to any one of Item 3. 5. The developer supply/discharge mechanism according to any one of claims 1 to 4, wherein the container for collecting the used developer in the developing machine is an empty container that used to contain new developer. .