JPH07122768B2 - Developing device for wet electrophotographic copying machine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a developing device for a wet electrophotographic copying machine.

(Prior Art) As is well known, in a developing device for a wet electrophotographic copying machine, a liquid developer is constituted by toner particles and a toner-carrying liquid in which the toner particles are dispersed, and the liquid developer is applied to a photoreceptor. The toner particles are electrostatically attached to the electrostatic latent image on the photoconductor to perform visible image processing.

An example of the developing device described above will now be described with reference to FIG.

That is, around the photosensitive drum 1 rotating in the direction of the arrow in FIG. 2, a charger 2 for applying a predetermined polarity, an exposure device 3, an eraser 4, a developing device 5, and a transfer device 6 are provided.
And a cleaning device 7 are arranged respectively.

The developing device 5 is provided in the vicinity of the photoconductor drum 1, and is provided with a developing container 5A in which a supply nozzle 5a for supplying the liquid developer is formed in the upper part and a recovery port 5b for the liquid developer is formed in the lower part. .

Then, inside the developing container 5A, a plurality of first and second developing rollers 5B and 5C are arranged along the peripheral surface of the photosensitive drum 1.
Equipped with squeeze roller 5D.

The first and second developing rollers 5B and 5C are arranged close to the peripheral surface of the photosensitive drum 1 with a gap of about 1 m / m, and rotate in the direction of the arrow shown in the drawing, that is, in the direction in which the photosensitive drum 1 moves around. It is possible. The squeeze roller 5D is located below the developing rollers 5B and 5C, comes into contact with the photosensitive drum 1, and rotates in the opposite direction to the developing rollers 5B and 5C.

In addition, the developing rollers 5B and 5C and the squeeze roller 5 described above
The scraper 5E is in contact with the peripheral surface of D.

In the vicinity of the developing container 5A, a developer containing a liquid developer composed of a resin, toner particles containing a pigment as a main component, and a toner carrying liquid containing an aliphatic hydrocarbon as a main component in which the toner particles are dispersed is stored. The agent tank 5F is arranged.

In the developer tank 5F, a pumping pump 5G for pumping the liquid developer toward the developing container 5A is arranged, and the tip of the rotary shaft of the pumping pump 5G penetrates into the liquid developer. And has a rotary vane 5G for pumping.

The pump 5G and the supply nozzle 5a of the developing container 5A are pipes.
The other end of the pipe 5J, which is connected by 5H and whose one end is connected to the recovery port 5b of the developing container 5A, penetrates into the liquid developer in the developer tank 5F.

A concentration sensor 5K that detects the concentration of the developer in the developer tank 5F is connected to the pumping pump 5G through a pipe 5L, and the pumping pump 5G is agitated by the pumping pump 5G. A pipe 5M for returning the liquid developer into the developer tank 5F is connected.

In such a developing device, the liquid developer drawn from the developer tank 5F by the drawing pump 5G is supplied to the supply nozzle.
It is supplied to the first developing roller 5B via 5a. The liquid developer supplied to the first developing roller 5B is the same as the scraper 5E and the first developer.
It collects between the developing roller 5B and the first developing roller 5B and is supplied onto the photosensitive drum 1 by the rotation of the first developing roller 5B, and the scrap remaining on the peripheral surface of the first developing roller 5B is scraped off by the scraper 5E and It accumulates between the developing roller 5C and the scraper 5E, and is supplied onto the photosensitive drum 1 by the rotation of the second developing roller 5C, like the first developing roller 5B. And the second
The developer remaining on the peripheral surface of the developing roller 5C is scraped off by the scraper 5E and flows down to the lower part of the developing container 5A. At the same time, the excess developer remaining on the photoconductor drum 1 is removed from the photoconductor drum 1 by the squeeze roller 5D, and the developer that flows down to the lower part of the developing container 5A is collected. Developer tank via mouth 5b and pipe 5J
Return to 5F.

By the way, the supply nozzle of developer container 5A from developer tank 5F
The toner particles in the liquid developer supplied onto the photoconductor drum 1 via 5a are electrostatically attached to the electrostatic latent image on the photoconductor drum 1 and consumed, whereby the developer tank
The content in 5F will decrease. For this reason, the developer tank
For 5F, new toner particles are replenished.

In replenishing such toner particles, for example, an ink type replenishment toner having a mixing ratio of the toner particles and the toner carrying liquid of 11:89 is used, and the toner particles in the replenishment toner are contained in the liquid developer. By being mixed, the concentration as a liquid developer is stabilized.

However, when the image on the photosensitive drum 1 is, for example, a black solid image having a large area ratio with respect to the original image, the amount of toner particles consumed is increased, so that the concentration of the liquid developer is stabilized. For this purpose, it is necessary to replenish the replenishment toner to make up for the shortage of toner particles. in this case,
As described above, since the content of the toner-carrying liquid is larger than the content of the toner particles in the replenishing toner, when the replenishing toner is supplied into the liquid developer, the toner-carrying liquid of the toner carrying liquid is The total body volume will inevitably increase. Therefore, in the developer tank 5F, there is a possibility that the toner carrying liquid may overflow from the developer tank 5F due to the replenishment of new toner carrying liquid in addition to the remaining toner carrying liquid.

Therefore, conventionally, the developer tank 5F is provided with a sensor 5N (see FIG. 2) for detecting the liquid level, and
The amount of developer contained in the 5th floor was regulated. However,
In such a structure, for example, if a small developer tank is used, the capacity of the tank is small. Therefore, in the case of image processing with a lot of black solid portions, the toner carrying is accompanied by the replenishment of toner particles. Since the replenishment of the liquid also increases, the stop of the replenishing device by the sensor 5N is accelerated, and it is difficult to secure the developer having the desired mixing ratio in the developer tank.

(Object) The object of the present invention is to solve the problems in the conventional developing device.
The concentration of the liquid developer can be stabilized by reducing the replenishment amount of the replenishment toner during image processing with many solid black portions, and the toner carrying liquid overflows when the replenishment toner is supplied for the purpose of stabilizing the concentration. Of the liquid developer by improving the mixing property between the replenishment toner and the toner-carrying liquid and replenishing the toner with a high solid content to prevent the replenishment toner from being biased. It is an object of the present invention to provide a developing device for a wet electrophotographic copying machine capable of stabilizing the temperature.

(Structure) In order to achieve this object, the present invention is to disperse a toner-supporting liquid containing an aliphatic hydrocarbon as a main component and a toner particle containing a resin or a pigment as a main component in the toner-supporting liquid. A developing device for a wet electrophotographic copying machine using the configured liquid developer, the developing device being equipped in the developing device, having a stirring means for supplying the liquid developer therein, and a developing tank in the developing tank. It has an introducing means communicating with the agitating and supplying means, and has 1000 parts by weight of the toner-carrying liquid inside.
The replenishment tank containing the replenishment toner composed of high solid content in which the toner particles are dispersed with the content of 200 to 1000 parts by weight, and the agitation supply means in the introduction means are arranged in the communicating portion. It is characterized by having a mesh.

In the present invention, by using the replenishment toner having a high solid content, it is possible to generate the developer having a predetermined concentration without increasing the amount of the toner-carrying liquid, and the replenishment toner is
Since the fine particles are formed by the mesh, the diffusibility in the toner carrying liquid is improved, and the mixing property in the toner carrying liquid is improved.

Hereinafter, the details of the embodiment of the present invention will be described with reference to FIG.

FIG. 1 shows a part of the developer tank 5F in FIG.

The feature of the embodiment shown in the figure is that the replenishment tank containing the replenishment toner in the case of using the replenishment toner having a high solid content and the pump for pumping and supplying the replenishment toner by the introduction means. This is because a pipe is directly connected, and a mesh for atomizing the replenishment toner into fine particles is provided in the communication part corresponding to the direct connection part of the pumping pump in the introducing means.

That is, in FIG. 1, the rotary vanes 5G of the pumping pump 5G
_{In the} pump chamber 5G ₂ capable of supplying the replenishment toner introduced therein with stirring, an introduction port 5G ₃ is formed in the center of the bottom wall thereof, and the introduction port 5G ₃ is provided in this introduction port 5G ₃ . A mesh 10 is attached to the outside of the bottom wall so as to cover it, which is a means for introducing replenishment toner, and one end of an introduction pipe 11 is connected to the outside of the bottom wall.

The other end of this introduction pipe 11 is connected to a supply pump 12, and this supply pump 12 is connected on the introduction side to an opening 13a of a replenishment tank 13 located downward.

The replenishment tank 13 is held and opened by a funnel-shaped receiving member 14.
13a is set to face downward, and a replenishment toner in which toner particles are dispersed at a content ratio of 200 to 1000 parts by weight with respect to 1000 parts by weight of a toner carrying liquid is stored inside.

On the other hand, an end of a pipe 5H connected to a supply nozzle 5a of a developing container 5A (see FIG. 2) is connected to the upper wall of the pump chamber 5G ₂ and liquid developer is stored in the developer tank 5F. The end of the pipe 5M for reflux is connected.

In the vicinity of the inlet 5G _{3 on} the bottom wall of the pump chamber 5G _2, a plurality of inlets 5G ₄ for taking the developer in the developer tank 5F into the pump chamber are opened.

Since the present embodiment is configured as described above, the supply pump 12 is operated during the replenishment of toner particles, and the replenishment toner in the replenishment tank 13 is pressure-fed toward the pump chamber 5G ₂ .

At this time, since the rotary blade 5G _{1 of the} pumping pump 5G is also rotating, the replenishment toner is sucked into the pump chamber 5G ₂ .
The particles are filtered by the mesh 10 of the inlet 5G ₃ , the size of the particles is reduced and sucked, and the particles are stirred by the rotary blade 5G ₁ to be further miniaturized to improve the mixing property in the toner-carrying liquid.

On the other hand, as the rotary blade 5G ₁ rotates, the developer in the developer tank 5F is also sucked into the pump chamber 5G ₂ via the intake port 5G ₄ , so that the above-mentioned replenishment toner is diffused into the developer.

In this way, the liquid developer in a state where the replenishment toner is diffused in the developer is pressure-fed to the developing container 5 through the pipe 5H and is also recirculated into the developer tank 5F through the pipe 5M.

In the present embodiment, the developer sent to the developing container 5 by positioning the mesh 15 having a passage area smaller than that of the mesh 10 provided in the inlet 5G ₃ in the opening to which the pipe 5H is connected. The particle diameter of the toner inside is made fine.

In this embodiment, since the mesh and the rotary blades of the pumping pump are used to make the toner particles having high solidity fine, it is not necessary to use a special means for making the particles fine.

In this embodiment, the replenishment toner can be easily diffused well by a simple structure in which the replenishment toner replenishment path is directly connected to the liquid developer pumping pump and the pump chamber.

(Effect) As is apparent from the above description, according to the present invention, the concentration of the liquid developer can be reduced even if the amount of the replenishment toner is reduced by using the replenishment toner having the high solid content by increasing the content of the toner particles. Since it is possible to stabilize the liquid developer, it is possible to suppress an increase in the toner carrying liquid generated at the time of replenishment of the replenishment toner, and as a result, the amount of the toner carrying liquid newly added to the liquid developer is reduced to reduce the liquid developer. It is possible to prevent the situation in which the toner-carrying liquid overflows because the degree of increase in the liquid level is low. Moreover, since deterioration of the diffusivity of the replenishment toner into the toner-carrying liquid, which occurs when the high solid content replenishment toner is replenished, can be prevented by making fine particles by using the mesh and the stirring blade. It becomes possible to prevent the concentration from becoming unstable due to the uneven distribution of the toner in the developing solution because the miscibility with the supporting solution is improved.

Therefore, in such a state, an additional effect that the interval until the supply stop due to the liquid level detection can be lengthened can be obtained.

In addition, the liquid failure that occurs in the conventional replenishment toner can be prevented by the high solid content replenishment toner,
As a result, it is possible to prevent the worker's hands and the surroundings of the replenishment unit from being damaged by the replenishment toner.

[Brief description of drawings]

FIG. 1 is a liquid surface view of essential parts of a developing device using an embodiment of the present invention, and FIG. 2 is a sectional view showing an example of a wet electrophotographic copying machine using the embodiment of the present invention. 1 ... Photosensitive drum, 5 ... Developer tank, 5A ... Developing container, 5a ... Supply nozzle, 5F ... Developing tank, 5G ... Pumping pump, 5G ... Inlet port, 11 ... Introducing pipe ,13……
Supply tank.

Front page continuation (72) Yoshio Sato Inventor Yoshio Sato 1-3, Shinmeidou, Nakameisei, Shibata-cho, Shibata-gun, Miyagi Tohoku Ricoh Co., Ltd. (56) Reference JP-A-61-14666 (JP, A)

Claims (1)

[Claims] 1. Wet electrophotography using a liquid developer constituted by dispersing a toner-supporting liquid containing an aliphatic hydrocarbon as a main component and toner particles containing a resin or a pigment as a main component in the toner-supporting liquid. A developing device for a copying machine, which is provided in the developing device, has a developing tank having a stirring and supplying means for the liquid developer therein, and an introducing means communicating with the stirring and supplying means in the developing tank. Then, the inside of the toner carrying liquid is 200 parts with respect to 1000 parts by weight.
To a mesh arranged in a communication portion between a replenishment tank containing a replenishment toner having a high solid content in which toner particles are dispersed with a content rate of 1000 parts by weight and the stirring and feeding means in the introducing means. And a developing device for a wet-type electronic ejector.