JP2817866B2 - Excess developer removal device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for removing excess developer in a wet electrophotographic apparatus.

[0002]

2. Description of the Related Art In a wet electrophotographic apparatus in which an electrostatic latent image is formed on a photosensitive material and the latent image is developed into a visible image by developing the latent image with a wet developing apparatus, an image after passing through the developing apparatus is developed. It is inevitable that the developer remains on the surface of the carrier,
If this residual developer is left unattended, there is an inconvenience that the quality of the completed image deteriorates. For this reason, conventionally, after a toner image is formed on the surface of an image carrier by a developing device, excess developer remaining on the surface of the image carrier is removed by a surplus developer removing device such as a so-called blade device, corona squeezing device, or air knife device. I am trying to do it. Among these excess developer removing devices, the removing device using an air knife device has an advantage that the toner image on the surface of the image carrier is less disturbed and the configuration is relatively simple. Widely used.

[0003]

However, the conventional developing apparatus using an air knife apparatus has a serious disadvantage in that the efficiency of removing the developing solution is low and the developing solution cannot be sufficiently removed. there were. Also, if the amount of air supplied to the air knife device is increased to increase the removal efficiency and the jet air pressure is set too high, the toner image on the surface of the image carrier is disturbed, or the developer is bubbled or scattered. And the amount of evaporation of the developer increases.

[0004]

SUMMARY OF THE INVENTION The inventors of the present invention have developed a configuration of a developing electrode for supplying a developing solution to the surface of an image carrier, in order to realize a sufficient surplus developing solution removing action by an air knife device. As a result of intensive studies on the position of the electrode with respect to the rotating drum, and further on the positional relationship between the developing electrode 3 and the nozzle of the air knife, the inventors have invented a surplus developer removing apparatus which can solve the above-mentioned problems by the following means. is there.

That is, the invention according to claim 1 is an apparatus for removing a surplus developer used in a wet electrophotographic apparatus for supplying a developer to a photosensitive material on which a latent image is formed and developing it into a visible image. A rotating drum that carries the photosensitive material and is driven to rotate about a substantially horizontal axis; and all or all of a surface facing the rotating drum upstream of a rotating direction of the rotating drum immediately below the rotating drum. A developing electrode, which is mostly disposed, and a nozzle that blows out the air supplied from the air supply device is provided near the downstream side of the developing electrode, and the downstream side surface of the developing electrode is the downstream side. A surplus developer removing device characterized by forming an obtuse angle with a tangent plane on the outer peripheral surface of the rotary drum immediately above the side surface. "

According to a second aspect of the present invention, there is provided an air distribution device for diverting air generated by the air supply device and supplying the divided air to a heat fixing device provided downstream of the nozzle and the nozzle. 2. The apparatus for removing surplus developer according to claim 1, wherein:

[0007]

[0008]

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing a schematic configuration around a surplus developer removing device according to one embodiment of the present invention. Reference numeral 1 denotes a rotary drum, which carries a photosensitive paper 9 on its outer peripheral surface and is driven to rotate in the direction of arrow A. Reference numeral 2 denotes a developing device.
A developing electrode 3 extending in a direction slightly perpendicular to the plane of the drawing and slightly shorter than the generatrix of the rotary drum 1, and a developing solution collecting drain 4 for collecting developing solution overflowing from the developing electrode 3. I have.

The developing device 2 is configured to be able to move up and down between at least two positions between a developing position (the state shown in FIG. 1) and a retracted position lowered in the direction of arrow B by an elevating device (not shown). In the state of the developing position, a predetermined gap (hereinafter, referred to as “gap”) is formed between the opposing surface 3 e of the developing electrode 3 and the outer peripheral surface of the rotary drum 1, and the opposing surface 3 e of the developing electrode 3 is formed. The whole or most of the surface is located at the lowest position of the rotary drum 1 (hereinafter referred to as “drum lowest point 1a”).
That. ) Is configured to be located on the upstream side. Further, when the developing device 2 is in the developing position, the angle formed between the tangent plane at the drum lowermost point 1a of the rotating drum 1 and the downstream side surface 3d of the developing electrode 3 is obtuse. As described later, the nozzle 5a
It is configured such that the flow of air blown out from along the side surface 3d.

A developing solution supplied from a developing solution storage tank (not shown) is supplied to a developing solution supply port 3a of the developing electrode 3, and a developing solution outlet connected to a gap via a developing solution supply passage 3b in the developing electrode 3. 3c, the gap is filled with the developing solution, and the developing solution overflowing from the gap is mostly discharged from the side surface 3 on the downstream side of the developing electrode 3.
d and flows down to the developer recovery drain 4. In this manner, the developer recovery drain 4
The collected developer is recovered by the hose (not shown) or the like again to the developer storage tank and circulated. Reference numeral 5 denotes a device for removing excess developer, which is a blower 5c for accelerating and sending out air, and two nozzles 5a extending over a range slightly shorter than the generatrix of the rotary drum 1 in the direction perpendicular to the plane of FIG. , 5b.

The photosensitive paper 9 carried on the outer peripheral surface of the rotary drum 1 is uniformly charged by a well-known charger (not shown) as the rotary drum 1 rotates in the direction of arrow A, and then is not shown. Scanning is performed by a known optical device, an electrostatic latent image is formed, and the electrostatic latent image is moved to the developing device 2. Developing electrode 3
As described above, the gap formed by the opposing surface 3e of the rotating drum 1 and the outer peripheral surface of the rotating drum 1 is filled with the developer successively. Developed into a visible image. In this manner, the photosensitive paper 9 in the portion where the electrostatic latent image is developed is separated from the opposing surface 3 e of the developing electrode 3 by the rotation of the rotating drum 1 and passes through the downstream side surface 3 d of the developing electrode 3. The developer adhering and remaining on the surface of the developing solution removing device 5 is pushed back toward the side surface 3d of the developing electrode 3 by the air flow blown from the nozzle 5a, and flows down together with the air flow descending along the side surface 3d. The developer is collected by the developer collecting drain 4.

The photosensitive paper 9 from which the excess developer has been removed
Is further conveyed to the downstream side by the rotation of the rotary drum 1, is heated by the heat fixing device 6, and is divided by the air flow generated by the blower 5 c and supplied from the nozzle 5 b to be dried and fixed. As described above, in the fixing process of the present apparatus, since the air flow is supplied simultaneously with the heat from the thermal fixing device 6, the fixing process can be performed quickly and reliably. Is obtained by diverting the air flow generated by the blower 5c of the excess developing solution removing device, so that there is no need to provide a separate blowing device, which contributes to downsizing of the device.

Next, the positional relationship between the developing electrode 3 and the nozzle 5a and the shape of the developing electrode 3, which are essential parts of the present invention, will be described with reference to FIGS. FIG. 2A is a partially enlarged view showing the positional relationship between the developing electrode 3 of the present invention and the nozzle 5 a, and the nozzle 5 a is provided near the downstream side of the developing electrode 3. In this case, the side surface 3d of the developing electrode 3 and the nozzle 5
The maximum value G1 is determined by the maximum allowable value depending on the characteristics of the photosensitive paper, the characteristics of the developing solution, the rotation speed of the rotary drum, and the like.
What is necessary is just to set it to a range in which a liquid pool of the developing solution does not occur between the developing electrode 3 and the nozzle 5a and the developing solution is not transmitted to the nozzle. According to experiments by the present inventors, when this interval G1 is set to an appropriate value equal to or less than the maximum value, a liquid pool 7a (see FIG. 3A) is provided between the developing electrode 3 and the nozzle 5a. ) Was not observed, and it was confirmed that almost all of the excess developer flowed down along the downstream side surface 3d of the developing electrode.

On the other hand, when the interval G2 is set to be equal to or more than the maximum value as shown in FIG. 3A, the liquid pool 7a is located between the downstream side surface 3d of the developing electrode 3 and the nozzle 5a.
Was found to occur. In the case of FIG. 3A, since the distance G2 between the developing electrode 3 and the nozzle 5a is relatively large, the developing solution 7 receives a force to push it back to the developing electrode 3 by the airflow blown out from the nozzle 5a, but at the same time, the rotating drum Since the force in the same direction as the rotation direction of the rotary drum 1 acts on the developer 7 by the rotation in the direction of the arrow A of 1, the developer 7 pushed back by the nozzle 5a becomes a droplet,
It is considered that a liquid pool 7a is generated between the developing electrode 3 and the nozzle 5a. In addition, in the case of FIG. 3, when all of the opposing surfaces 3e of the developing electrode 3 are located upstream of the lowermost point 1a of the drum, gravity also acts on the developing solution 7 so that the rotating drum 1 This is considered to be a force that pulls the developer 7 in the direction of the arrow A that is the rotation direction.

On the other hand, in the case of FIG. 2A, since the distance G1 between the developing electrode 3 and the nozzle 5a is relatively small, the pressure of the airflow blown out from the nozzle 5a is lower than that of the facing surface 3e of the developing electrode 3. Since the developer 7 acts directly on the rear end (the end on the most downstream side), the developer 7 is immediately separated from the photosensitive paper 9 without being transported in the direction of the nozzle 5 a while adhering to the photosensitive paper 9, and It is thought that it flows down the side surface 3d.
Further, at this time, as described above, since the angle formed between the tangent plane at the drum lowermost point 1a of the rotating drum 1 and the side surface 3d on the downstream side of the developing electrode 3 is an obtuse angle, the nozzle The flow of the air blown out from 5a flows down along the side surface 3d together with the developing solution 7 as shown by an arrow 8 without generating a large turbulence.

Next, when the nozzles 5a are arranged at intervals G1 as shown in FIG. 2A, and when the nozzles 5a are arranged at intervals G2 as shown in FIG.
In the case where the nozzle 5a is disposed in the above, four line segments 10a to 10d parallel to the rotation direction (the direction of arrow A) of the rotary drum 1 as shown in FIG. A case will be described in which a pattern composed of two line segments 11a and 11b in the directions is to be developed. FIG. 2 (B)
Is the distance G1 between the developing electrode 3 and the nozzle 5a in FIG.
Of the photosensitive paper 9 when cut in the axial direction of the rotary drum 1 at a substantially intermediate point of the toner particles 7 used for development.
FIG. 3B is a diagram schematically showing the state of FIG. 3C, and FIG. 3B is a view of the rotary drum 1 cut in the axial direction at a substantially middle point of the interval G2 between the developing electrode 3 and the nozzle 5a in FIG. FIG. 4 is a diagram schematically showing a state of toner particles 7c used for development on a cross section of the photosensitive paper 9 and surplus toner particles 7d in the case of the above.

Since the bias voltage applied to the developing electrode 3 does not act on the portion of the liquid reservoir 7a generated in the case of FIG. 3A, the excess toner particles 7d in the liquid reservoir 7a Are gathered by electrophoresis on the line segments 10a to 10d, which are contour portions. The surplus toner particles 7d flow in the direction opposite to the rotation direction of the rotary drum 1 (the direction of arrow A), and so-called streaks (right portions of the line segment 11b in FIG. 3C). Tailing) 12a to 12d
Will occur. On the other hand, at the interval G1, the nozzle 5a
In the case of FIG. 2 (A) in which is disposed, all the excess toner flows down along the side surface 3d of the developing electrode 3 without causing the liquid pool as described above, so that as shown in FIG. Only the toner particles 7c which should be subjected to the development are adhered to the photosensitive paper 9 and remain, and so-called streaks (tails) in the non-image portion (the right portion of the line segment 11b in FIG. 2C). Problem is solved.

[0019]

As described above, according to the surplus developer removing apparatus of the present invention, a sufficient efficiency of removing the surplus developer can be obtained without disturbing the toner image. The problem is solved and a high-quality image can be obtained. Further, bubbling, scattering, evaporation and the like of the developer can be extremely reduced. Furthermore, since the air is divided and supplied to the fixing device, the function of the fixing device can be improved, and at this time, there is no need to separately provide an air supply device for the fixing device, which contributes to downsizing of the device. Things.

[Brief description of the drawings]

FIG. 1 is a side view showing a schematic configuration around an excess developer removing device according to an embodiment of the present invention.

FIG. 2 is a view for explaining the principle of an excess developer removing device according to one embodiment of the present invention.

FIG. 3 is a diagram for explaining the principle of an excess developer removing device according to one embodiment of the present invention.

[Description of Signs] 1 Rotary drum 2 Developing device 3 Developing electrode 4 Developing solution collecting drain 5 Excess developing solution removing device 6 Thermal fixing device 7 Developing solution 9 Photosensitive paper

Claims (2)

(57) [Claims] An apparatus for removing surplus developer used in a wet electrophotographic apparatus for supplying a developer to a photosensitive material on which a latent image is formed and developing the visible image by developing a visible image. A rotary drum that is driven to rotate about a substantially horizontal axis; and a developing electrode having a whole or most of a surface facing the rotary drum disposed immediately below the rotary drum and upstream in a rotation direction of the rotary drum. A nozzle that blows out the air supplied from the air supply device is provided near the downstream side of the developing electrode, and a downstream side surface of the developing electrode has an outer periphery of the rotary drum immediately above the downstream side surface. An apparatus for removing surplus developer, wherein an obtuse angle is formed with respect to a tangent plane of the surface. 2. An air diverting means for diverting air generated by the air supply device and supplying the diverted air to a thermal fixing device provided downstream of the nozzle and the nozzle, respectively. Item 6. An excess developer removing device according to Item 1.