JPH09244416A - Wet developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain specified image density in a short time by providing an electric field forming means forming electric field by which toner particles in developer are moved in a direction where they go away from a developing roller on an area (pre-area) carrying the developer from a developer reservoir part to the surface of a latent image carrier. SOLUTION: This device is provided with the electric field forming means 8 forming the electric, field by which toner particles in the developer are moved in the direction where they go away from the developing roller 3 on a pre- developing area 6. After the developer drawn up from the developer reservoir part 5 by the roller 3 is carried to the area 6, it reaches a developing gap area 7, where development is performed to an electrostatic latent image. In the case the toner particles have negative electrostatic charge, the means 8 forms the electric field in a direction shown by an arrow for the area 6. Since the toner particles are moved in the direction where they go away from the roller 3 by the action of the electric field, density distribution where the toner particles are attracted to the level of the developer is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet image forming apparatus such as a copying machine, a facsimile or a printer, which forms an image by a wet electrophotographic method, and more specifically, toner particles of a developer existing on the surface of a developing roller. The present invention relates to a wet-type developing device capable of efficiently performing development by concentrating the components on the developer surface side.

[0002]

2. Description of the Related Art Conventionally, a latent image formed on a latent image carrier is developed by using a developing solution in which toner is dispersed in a liquid carrier to form a toner image on the latent image carrier. Then, a wet developing device is known which transfers the toner image to a transfer material to form an image. In this device, in order to attach toner to the surface of the latent image carrier at the time of development or to move the toner from the surface of the latent image carrier to the transfer material at the time of transfer, electrostatic charge of toner particles charged by the liquid carrier is used. It utilizes the phenomenon of migration.

As a method for supplying a developing solution to the surface of a latent image carrier, a developing roller method is currently popular. In this system, the developer is pumped up by the rotation of the developing roller, so that the developer is always supplied to the surface of the latent image carrier sufficiently, and the developing roller itself also functions as a counter electrode. Therefore, it is suitable for high-speed development of an electrostatic latent image. In order to achieve higher speed development by using such a developing roller system, the toner concentration in the developing solution is increased or the rotation speed of the developing roller is increased so that a predetermined image density can be obtained in a short time. Increase the supply of developer,
It is conceivable to increase the latent image potential of the latent image carrier. However, increasing the toner concentration in the developer causes a non-negligible problem such as toner agglomeration and sticking. Further, if the rotation speed of the developing roller is increased, the developed image on the latent image is disturbed by that momentum, which adversely affects the image quality. Will be given. Further, even if an attempt is made to increase the latent image potential, the capacity of the latent image carrier is limited. Therefore, it has been proposed to use a plurality of developing rollers to achieve high-speed development.

[0004]

However, in order to obtain a high-quality image in a wet process, various devices other than the developing roller are arranged around the latent image carrier. It was difficult to obtain the space to arrange multiple lines. In this way, the toner density is such that aggregation or sticking of toner does not become a problem, the developing roller rotation speed is such that the image is not disturbed, and the latent image potential is such that the latent image carrier is not adversely affected. Further, in a situation where a space for arranging a plurality of developing rollers cannot be provided, it is difficult to attach toner particles sufficient to obtain a predetermined image density to the electrostatic latent image portion on the latent image carrier by wet high speed development. Met.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a wet developing apparatus capable of obtaining a predetermined image density in a short time in wet high speed development. is there.

[0006]

In order to achieve the above object, the invention of claim 1 forms an electrostatic latent image on the surface of a latent image carrier, and a developing solution is developed by a developing roller from a developing solution reservoir. In a wet developing device that develops the electrostatic latent image by transporting it to the surface of the latent image carrier, a region in which the developer is transported from the developer reservoir to the surface of the latent image carrier (hereinafter referred to as a pre-developing region). ), An electric field forming means for forming an electric field for moving the toner particles in the developing solution in a direction away from the developing roller.

According to a second aspect of the present invention, in the first aspect of the present invention, a fixed electrode facing the developing roller is used as the electric field forming means, and toner particles in a developing solution are applied to the fixed electrode on the fixed electrode side. The feature is that a voltage necessary for attracting is applied.

A third aspect of the present invention is characterized in that, in the second aspect of the invention, the fixed electrode is arranged in a state of not contacting the developing solution.

According to a fourth aspect of the invention, in the third aspect of the invention, the surface of the developing solution on the developing roller is smoothed before the developing solution passes through the region sandwiched between the developing roller and the fixed electrode. The liquid level smoothing means is provided.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the liquid level smoothing means is a liquid level smoothing roller arranged adjacent to the developing roller, or is arranged adjacent to the developing roller. It is characterized by using a blade.

According to a sixth aspect of the invention, in the fifth aspect of the invention, a cleaning blade is provided in contact with the liquid surface smoothing roller.

According to a seventh aspect of the present invention, in the first aspect of the present invention, a roller electrode disposed opposite to the developing roller is used as the electric field forming means, and toner particles in a developing solution are applied to the roller electrode. It is characterized in that a voltage necessary for attracting to the side is applied.

The invention of claim 8 is characterized in that, in the invention of claim 7, a cleaning blade is provided in contact with the roller electrode.

According to a ninth aspect of the invention, in the first aspect of the invention, the electric field forming means has a structure in which a plurality of conductor regions are divided and each conductor region is electrically insulated by an insulating layer. It is characterized in that a divided developing roller is used and voltages of different values are applied to the respective conductor regions of the divided developing roller.

According to a tenth aspect of the invention, in the ninth aspect of the invention, the divided developing roller has a conductor region in a radial pattern from the rotation center axis of the roller in a cross section in a direction orthogonal to the rotation axis of the division development roller. It is characterized in that it is divided and each conductor region is electrically insulated by an insulating layer.

The invention of claim 11 is characterized in that, in the invention of claim 9, liquid level smoothing means for smoothing the level of the developer on the split developing roller is provided.

According to a twelfth aspect of the present invention, in the eleventh aspect of the present invention, the liquid level smoothing means is a liquid level smoothing roller disposed adjacent to the split developing roller, or is disposed adjacent to the split developing roller. It is characterized by using a blade that has been cut.

According to a thirteenth aspect of the invention, in the twelfth aspect of the invention, a cleaning blade is provided in contact with the liquid surface smoothing roller.

According to a fourteenth aspect of the present invention, in the ninth aspect of the present invention, a counter electrode is provided so as to face the split developing roller.

According to a fifteenth aspect of the invention, in the ninth aspect of the invention, a voltage is applied to the conductor area existing in the pre-developing area so that the toner particles in the developer are separated from the split developing roller. A normal developing bias voltage is applied to the other conductor regions.

According to a sixteenth aspect of the present invention, in the invention of the ninth aspect, a normal developing bias voltage is applied to the conductor region existing in the region sandwiched by the divided developing roller and the latent image carrier.
A voltage that acts in the direction in which the toner particles in the developing solution are attracted to the split developing roller side is applied to the conductor area existing in the developer pool, and the toner in the developer is applied to the conductor area existing in the pre-developing area. It is characterized in that a voltage is applied to each of the particles in a direction of separating the particles from the split developing roller.

In the wet developing apparatus according to any one of claims 1 to 16, the toner particles in the developer passing through the pre-developing area are:
Since it moves in the direction away from the developing roller due to the action of the electric field by the electric field forming means, the density of toner particles in the vicinity of the surface of the latent image carrier of the developing solution entering the developing gap region sandwiched between the developing roller and the latent image carrier is The density of the toner particles in other parts is increased.

Particularly, in the wet developing apparatus of the second aspect, when a potential difference is applied between the fixed electrode arranged in the pre-developing area and the developing roller, the developing gap area sandwiched between the developing roller and the latent image carrier is formed. The density of toner particles in the vicinity of the surface of the latent image bearing member of the developing solution entering the toner is increased as compared with the density of toner particles in other portions.

In particular, in the wet type developing device of the third aspect, since the fixed electrode is arranged in a state where it does not come into contact with the developing solution, toner adhesion to the fixed electrode is avoided.

Particularly, in the wet type developing device of the fourth aspect, the surface of the developing solution on the developing roller is smoothed by the solution leveling means.

Particularly, in the wet type developing device of the fifth aspect, the smoothness of the developing liquid surface on the developing roller is increased by the liquid surface smoothing roller or blade arranged adjacent to the developing roller. When the rotation speed of the liquid surface smoothing roller or the amount of protrusion of the blade is changed, the amount of developer on the developing roller also changes.

Particularly, in the wet type developing device of the sixth aspect, the developing solution or the toner particles attached to the liquid level smoothing roller are removed by the cleaning blade provided in contact with the liquid level smoothing roller.

Further, particularly in the wet type developing apparatus of claim 7, when a potential difference is applied between the roller electrode provided in the pre-developing area and the developing roller, the developing gap area sandwiched between the developing roller and the latent image carrier is formed. The density of toner particles in the vicinity of the surface of the latent image bearing member of the developing solution entering the inside is increased more than the density of toner particles in other portions. Further, since the roller electrode has a rotating roller structure, the surface of the developing solution on the developing roller can be made smooth at the same time as the electric field is formed.

Particularly, in the wet developing apparatus according to the eighth aspect, the developing solution or toner particles attached to the roller electrode can be removed by the cleaning blade provided in contact with the roller electrode.

Further, particularly in the wet type developing device of the ninth aspect, when a potential difference is applied between the plurality of divided conductor regions, the development is carried out into the developing gap region sandwiched between the developing roller and the latent image carrier. The density of toner particles in the vicinity of the surface of the latent image bearing member of the liquid is higher than the density of toner particles in other portions. Further, different toner particle densities can be formed in the respective areas by applying appropriate voltages having different values to the respective areas.

In particular, in the wet developing device of the tenth aspect, when a plurality of conductor regions are selected and a voltage is applied, an electric field having a strength corresponding to the selected regions is formed on the surface of the split developing roller.

Further, particularly in the wet type developing apparatus of claim 11, the liquid level smoothing means provided on the split developing roller smoothes the developer level on the split developing roller.

In particular, in the wet developing apparatus according to the twelfth aspect, the smoothness of the developing solution surface on the split developing roller is increased by the liquid level smoothing roller or the blade arranged adjacent to the split developing roller. When the rotation speed of the liquid surface smoothing roller or the amount of protrusion of the blade is changed, the amount of developer on the developing roller also changes.

Particularly, in the wet developing apparatus of the thirteenth aspect, the developing solution or the toner particles attached to the liquid surface smoothing roller are removed by the cleaning blade provided in contact with the liquid surface smoothing roller.

In particular, in the wet developing apparatus of the fourteenth aspect, the electric field strength formed by the split developing roller can be increased by the counter electrode provided so as to face the split developing roller.

Further, in the wet developing device of the fifteenth aspect, a voltage acting in the direction of separating the toner particles from the developing roller is applied to the conductor region existing in the pre-development region, and the other conductor regions are usually subjected to the voltage. When the developing bias voltage of 1 is applied, it is possible to form an electric field that acts on the toner particles in different directions on each conductor region of the split developing roller.

In particular, in the wet type developing apparatus of claim 16, in addition to the effect of claim 15, an electric field that acts on the conductive material region existing in the developer pool to attract the toner particles to the developing roller. Can be formed.

[0038]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments 1 to 16 when the present invention is applied to an electrophotographic copying machine (hereinafter referred to as a copying machine) which is an image forming apparatus will be described below. [First Embodiment] FIG. 1 is a schematic configuration diagram of a copying machine according to the first embodiment. In FIG. 1, a photosensitive drum 1 as a latent image carrier is rotationally driven in a direction of an arrow at a constant speed during copying by a driving unit such as a motor (not shown).
Then, after being charged in the dark by a charging charger (not shown), a light image of the original is irradiated and imaged by an exposing device (not shown), and an electrostatic latent image is carried on the outer peripheral surface of the photosensitive drum 1. Then, the electrostatic latent image is transferred to the wet developing device 2
While being passed through the portion, the developing roller 3 develops the toner image. After that, the toner image is transferred by a transfer charger (not shown) onto a transfer sheet fed from a sheet feeding device (not shown). That is, the toner image is electrophoresed in the liquid carrier between the photosensitive drum 1 and the transfer paper,
The photosensitive drum 1 moves to the transfer paper.

In the wet developing device 2, the developing roller 3 is disposed so as to closely face the photosensitive drum 1.
The developing roller 3 is driven by a driving means such as a motor (not shown).
The photoconductor drum 1 is rotationally driven in the direction of the arrow that is the reverse rotation direction. The developing roller 3 is provided with a scraper 4 for scraping off the excess developer on the developing roller,
A region 5 surrounded by the developing roller 3 and the scraper 4 is supplied with a developing solution by a developing solution supplying means (not shown) to form a developing solution reservoir 5. The area where the developer is conveyed from the developer pool 5 to the surface of the photosensitive drum 1 is the pre-development area 6. The pre-development area 6 is provided with an electric field forming means 8 for forming an electric field in which toner particles in the developing solution move in a direction away from the developing roller 3. The developer drawn up from the developer pool 5 by the developing roller 3 is transferred to the pre-developing area 6 by the developing roller 3.
After being conveyed, the toner reaches the developing gap area 7 sandwiched between the developing roller 3 and the photoconductor drum 1, where the electrostatic latent image is developed.

When the toner particles have a negative electrostatic charge, the electric field forming means 8 forms an electric field in the arrow direction with respect to the pre-developing area 6. Then, the toner particles of the developer passing through the pre-development area 6 move in the direction away from the developing roller 3 due to the action of the electric field in the arrow direction.
It is possible to obtain a concentration distribution in which the toner particles are attracted to the developer surface (front surface side). That is, in the developer existing in the pre-development area 6, the toner concentration of the toner particles present in the area close to the developer surface is apparently higher than the toner concentration in the developing pool portion 5. The developer that has passed through the pre-developing area 6 enters the developing gap area 7 while having such a toner concentration distribution, so that the toner particles are used for development in a state of being concentrated near the surface of the photosensitive drum 1. (Hereinafter, margin)

During high-speed development, not only the linear velocity of the photosensitive drum 1 but also the linear velocity of the developing roller 3 is higher, so that the behavior of the toner particles in the developing gap area 7 is electrostatic. A direction that is dragged by the developing roller 3 rather than a speed that moves by electrophoresis in the direction of advancing to the latent image (a direction perpendicular to the surface of the photosensitive drum 1) (a direction that is approximately orthogonal to the direction that moves by lightning migration). It is known that the moving speed as a fluid to the is considerably higher. That is, most of the toner particles that can reach the electrostatic latent image in the developing gap area 7 are present near the surface of the photosensitive drum 1, so that if the toner particle density is concentrated in this area. Development can be performed efficiently.

According to the copying machine configured as described above,
At the time of development, an effect equivalent to that obtained by developing with an apparently high-concentration developing solution can be obtained, so that a predetermined image density can be obtained in a short time. Moreover, since it is not necessary to unnecessarily increase the toner concentration of the developer, it is possible to minimize the amount of toner particles aggregated or fixed in the developer reservoir 5.

[Second Embodiment] FIG. 2 is a schematic configuration diagram of a copying machine according to the second embodiment, in which the same parts as those in FIG. In the pre-development area 6 of the second embodiment,
As the electric field forming means 8 in FIG. 1, a metal fixed electrode 9 is arranged so as to face the developing roller 3. A power supply 10 is connected to the fixed electrode 9 and the developing roller 3, and a voltage required to attract the toner particles in the developing solution to the fixed electrode 9 side is applied to the fixed electrode 9. When the toner particles in the developer have a negative electrostatic charge, the voltage is applied so that the fixed electrode 9 has a higher potential than the developing roller 3. As the potential difference between the fixed electrode 9 and the developing roller 3, several hundred volts or more is applied. The fixed electrode 9 may have a flat plate shape, but a larger effect can be obtained if the fixed electrode 9 has a shape that matches the curvature of the developer surface adhering to the developing roller 3 as shown in the figure.

According to the copying machine configured as described above,
When a voltage required to attract the toner particles in the developing solution from the power source 10 to the fixed electrode 9 is applied to the fixed electrode 9, the pre-development area is generated by the action of the electric field generated between the fixed electrode 9 and the developing roller 3. The toner particles of the developer passing through 6 move in the direction away from the developing roller 3, so that the toner particles have a concentration distribution attracted to the developer surface (front surface side). Therefore, at the time of development, it is possible to obtain the same effect as that obtained by developing with a developer having an apparently high concentration, and a predetermined image density can be obtained in a short time. Further, since the fixed electrode 9 has a simple structure, it can be easily attached, and the cost and space can be saved.

[Third Embodiment] FIG. 3 is a schematic configuration diagram of a copying machine according to the third embodiment, and the same parts as those in FIG. 2 are denoted by the same reference numerals. In the pre-development area 6 of the third embodiment,
The fixed electrode 9 that is the same as that in FIG. 2 is attached without contacting the developer. Other configurations are the same as those in FIG.

According to the copying machine configured as described above,
Since the developing solution and the fixed electrode 9 are not in direct contact with each other, there is no fear that the toner of the developing solution passing through the pre-development area 6 adheres to the fixed electrode 9. Therefore, the gap between the developing roller 3 and the fixed electrode 9 is not closed by the toner adhesion, and stable electric field formation can be always performed.

[Fourth Embodiment] FIG. 4 is a schematic configuration diagram of a copying machine according to the fourth embodiment, and the same parts as those in FIG. 2 are denoted by the same reference numerals. In the pre-development area 6 of this Embodiment 4,
Instead of the fixed electrode 9 shown in FIG. 3, a slightly smaller fixed electrode 11 is attached to the side closer to the photosensitive drum 1. Further, in a part of the pre-development area 6 on the developer pool 5 side, a developer surface smoothing means 12 for smoothing the surface of the developer carried to the fixed electrode 11 is arranged in contact with or not in contact with the developer. It is set up. In FIG. 4, when the developing roller 3 rotates, the toner particles and the carrier liquid in the developing solution accumulated in the developing solution pool 5 are agitated, so that the surface of the developing solution drawn up by the developing roller 3 from the developing solution pool section 5. Unevenness is more likely to occur. If the surface of the developing solution has irregularities, the electric field formed by the fixed electrode 11 may become non-uniform. However, by providing the developing solution surface smoothing means 12 in the pre-development area 6, the developing solution surface passing between the fixed electrode 11 and the developing roller 3 can be smoothed. As the developing solution surface smoothing means 12 in contact with the developing solution,
For example, there is one that uses a rotating roller, and as the developing solution surface smoothing means 12 that is not in contact with the developing solution, there is a compressed air ejecting device that ejects compressed air from a slit and controls the thickness of the developing solution surface by the wind pressure. is there.

According to the copying machine configured as described above,
The developer level smoothing means 12 smoothes the level of the developer entering between the fixed electrode 11 and the developing roller 3, so that the concentration distribution of the toner particles attracted to the developer level can be made uniform. it can.

[Fifth Embodiment] FIG. 5 is a schematic configuration diagram of a copying machine according to the fifth embodiment, and the same parts as those in FIG. 4 are denoted by the same reference numerals. In the fifth embodiment, as the developing solution surface smoothing means 12 of FIG. 4, a developing solution surface smoothing roller 13 formed in a roller shape is provided. The developing solution surface smoothing roller 13 may be rotated in either direction, and by rotating it in one direction, the developing solution surface passing between the fixed electrode 11 and the developing roller 3 can be smoothed. Other configurations are the same as those in FIG.

According to the copying machine configured as described above,
Not only the same effect as in the fourth embodiment can be obtained, but since the developing solution surface smoothing means 12 has a roller structure, the developing solution can be attached to the developing solution without changing the rotation speed of the developing roller 3 by changing the rotation speed thereof. The amount of the developing solution used can be finely adjusted.

[Sixth Embodiment] FIG. 6 is a schematic configuration diagram of a copying machine according to the sixth embodiment, and the same parts as those in FIG. 5 are denoted by the same reference numerals. In the sixth embodiment, the cleaning blade 14 is disposed in contact with the developing solution surface smoothing roller 13 shown in FIG. This cleaning blade 14
Is provided when the developer surface smoothing roller 13 is rotating in the same direction as the developing roller 3. Other configurations are the same as those in FIG.

According to the copying machine configured as described above,
The cleaning blade 14 can prevent the developing solution that has circulated around the developing solution surface smoothing roller 13 from coming into contact with the developing solution surface again, so that the smoothness of the developing solution surface can be increased and the developing solution that has adhered to the developing solution surface smoothing roller 13 can be further improved. Alternatively, since toner stains can be removed, the effect of the developer surface smoothing roller 13 can be stabilized.

[Seventh Embodiment] FIG. 7 is a schematic configuration diagram of a copying machine according to the seventh embodiment, and the same parts as those in FIG. 5 are denoted by the same reference numerals. In the seventh embodiment, as the developer surface smoothing means 12 in FIG. 4, a blade-shaped developer surface smoothing blade 15 is provided. The developer surface smoothing blade 15 can smooth the surface of the developer passing between the fixed electrode 11 and the developing roller 3. Other configurations are the same as those in FIG.

According to the copying machine configured as described above,
Not only the same effect as in Embodiment 4 can be obtained, but since the developer surface smoothing means 12 has a blade structure, the amount of protrusion to the developing roller 3 can be adjusted to adjust the amount of protrusion to the developing roller 3.
The amount of developer can be finely adjusted without changing the number of revolutions. Further, the structure can be simplified as compared with a case where the developing solution surface smoothing means 12 has a roller structure.

[Embodiment 8] FIG. 8 is a schematic configuration diagram of a copying machine according to Embodiment 8, and the same parts as those in FIG. 2 are denoted by the same reference numerals. In the eighth embodiment, a roller electrode 16 having a roller structure is provided as the electric field forming means 8 shown in FIG. The roller electrode 16 is attached to the pre-developing area 6 at a position as close to the photosensitive drum 1 as possible, and is preferably placed in contact with the developing solution. The direction of rotation of the developer surface smoothing roller 13 may be either direction. Also,
A power supply 10 is connected to the roller electrode 16 and the developing roller 3, and a voltage necessary to attract the toner particles in the developing solution to the roller electrode 16 side is applied to the roller electrode 16.

According to the copying machine configured as described above,
When the voltage required to attract the toner particles in the developing solution from the power source 10 to the roller electrode 16 side is applied to the roller electrode 16, the pre-developing area is generated by the action of the electric field generated between the roller electrode 16 and the developing roller 3. Since the toner particles of the developer passing through 6 move away from the developing roller 3, the toner particle density on the developer surface side becomes high. Therefore, at the time of development, it is possible to obtain the same effect as that obtained by developing with a high-concentration developing solution, and it is possible to obtain a predetermined image density in a short time. Further, since the roller electrode 16 has a roller structure, the smoothness of the developing solution surface can be enhanced at the same time as the effect of attracting the toner particles to the developing solution surface side. Due to these two effects, the effect of attracting the toner particles can be stabilized. Further, by changing the number of rotations of the roller electrode 16, the developing roller 3
The amount of the developing solution attached to the developing solution can be finely adjusted without changing the number of rotations.

[Ninth Embodiment] FIG. 9 is a schematic configuration diagram of a copying machine according to the ninth embodiment, and the same portions as those in FIG. 8 are denoted by the same reference numerals. In the ninth embodiment, the cleaning blade 17 is arranged in contact with the roller electrode 16 shown in FIG. The cleaning blade 17 is provided when the roller electrode 16 is rotating in the same direction as the developing roller 3. Other configurations are the same as those in FIG.

According to the copying machine configured as described above,
The cleaning blade 17 can prevent the developer that has circulated around the roller electrode 16 from coming into contact with the surface of the developer again, so that the smoothness of the surface of the developer is increased, and further, the roller electrode 16
Since the developer, toner stains, and the like attached to the roller electrode 16 can be removed, the effect of the roller electrode 16 can be stabilized.

[Embodiment 10] FIG. 10 shows Embodiment 10.
FIG. 2 is a schematic configuration diagram of the copying machine according to the first embodiment, and as the electric field forming means 8 shown in FIG.
Are arranged. In the divided developing roller 18, when the side surface (or cross section) of the roller is viewed in the longitudinal direction as shown in the figure, the conductor regions forming the roller are divided into a plurality of regions, and each conductor region is electrically insulated by an insulator. The structure is electrically isolated. Therefore, the split developing roller 18
The conductor regions can be divided into several groups by externally supplying a voltage to the predetermined conductor regions.
A region 19 in FIG. 10 is a set of conductor regions located in the pre-development region 6, and a region 20 is a set of conductor regions located in the development gap region 7. The number of divisions of the conductor region is preferably as large as possible so that regions having the same potential can be selected finely. On the other hand, when the split developing roller 18 is viewed from the direction orthogonal to the rotation axis,
The side surface of the conductor region is finely divided into a plurality of parts (not shown). The division shape may be, for example, a grid shape or a honeycomb shape. Further, a voltage is supplied to each of the divided conductor regions from a portion other than the portion where the divided developing roller 18 contacts the developing solution. A commutator, for example, can be used to supply a voltage to each conductor region.

When the toner particles have a negative electrostatic charge, as shown in FIG. 10, among the plurality of conductor regions of the developing roller 18, the conductive body region in contact with the pre-developing region 6 is formed. 19 is supplied with a negative voltage by the power source 10a, and the conductor region 20 in contact with the developing gap region 7 is supplied with the power source 10a.
A positive voltage as a normal developing bias is applied by b. When the toner particles have a positive electrostatic charge, a positive voltage is applied to the conductive body region 19 of the plurality of conductive regions of the developing roller 18 which is in contact with the pre-developing region 6. Further, a negative voltage as a normal developing bias is applied to the conductor region 20 in contact with the developing gap region 7.

According to the copying machine configured as described above,
When different voltages are applied to the areas 19 and 20 of the divisional developing roller 18, the toner particles of the developer passing through the pre-development area 6 are separated from the divisional developing roller 18 by the action of the electric field generated between the areas 19 and 20. Since the toner particles move in the direction away from each other, the toner particles have a density distribution that is attracted to the surface of the developer. That is, with respect to the developer intervening in the developing gap area 7, the toner particle density in the vicinity of the surface of the photosensitive drum can be made higher than the toner particle densities in other parts, so that the developer is apparently developed with a high concentration developer. The same effect as that obtained can be obtained, and a predetermined image density can be obtained in a short time. Further, since voltages having different values can be applied to the respective conductor areas of the divisional developing roller 18, the density distribution of the toner particles can be finely controlled by appropriately selecting the area to which the voltage is applied as necessary. You can Further, since no extra space is required for installing the electric field forming means, it is possible to save space.

[Embodiment 11] FIG. 11 shows an eleventh embodiment.
3 is a conceptual perspective view of the split developing roller in FIG. In the eleventh embodiment, as the split developing roller 18 shown in FIG. 10, a split developing roller 21 which is electrically insulated and split radially from the center of the rotating shaft is used as shown in the figure. Each of the divided conductor regions 23 is formed in a strip shape as shown in one of the representative examples. In FIG. 11, the tip of the conductor region 23 reaches the center of the rotation axis of the split developing roller 21, but the split region does not necessarily have to reach the center of the rotation axis, for example, only near the surface of the split developing roller 21. Good. Further, for example, a ring-shaped electrode 22 can be used to supply a voltage to each conductor region of the split developing roller 21. The ring-shaped electrode 22 contacts one end of the rotating split developing roller 21 and is supported so as not to rotate together with the split developing roller 21. Further, the ring-shaped electrode 22 is divided into a plurality of pieces in an electrically insulated state, and when different voltages are applied to the respective electrodes, the ring-shaped electrodes which are in contact with the respective conductor regions of the rotating split developing roller 21 at that time. A voltage corresponding to the potential of 22 is applied. By changing the division range of the ring-shaped electrode 22,
The range of the electric field acting on the split developing roller 21 can be changed.

According to the copying machine configured as described above,
Since the split developing roller 18 is radially split from the center of the rotation axis, it is possible to selectively apply a voltage to a predetermined conductor region by using the split ring-shaped electrode 22 and the like. Therefore, the electric field region for attracting the toner particles to the developer surface side can be easily set.

[Embodiment 12] FIG.
It is a schematic block diagram of the copying machine which concerns on this, and shows the same part as FIG. 10 by the same code | symbol. In the pre-development area 6 shown in FIG.
A developer surface smoothing means 24 for smoothing the surface of the developer is provided in contact with or not in contact with the developer. As the developing solution surface smoothing means 24 in contact with the developing solution, there is, for example, one using a rotating roller, and as the developing solution surface smoothing means 12 not in contact with the developing solution, compressed air is jetted from a slit,
There is a compressed air jetting device or the like that controls the thickness of the surface of the developer by the wind pressure. The surface of the developer drawn up from the developer pool 5 by the split developing roller 18 is likely to have irregularities, and the electric field formed by the split developing roller 18 may become nonuniform. However, by providing the developing solution surface smoothing means 24 in the pre-developing area 6, the developing solution surface passing over the pre-developing area 6 of the split developing roller 3 can be smoothed.

According to the copying machine configured as described above,
Since the liquid level of the developer on the pre-developing area 6 is smoothed by the developer level smoothing means 24, the concentration distribution of the toner particles attracted to the developer level side can be made uniform in the split developing roller 18. .

[Thirteenth Embodiment] FIG. 13 shows a thirteenth embodiment.
FIG. 13 is a schematic configuration diagram of the copying machine according to FIG. In this embodiment 13, FIG.
As the developing solution surface smoothing means 24, a developing solution surface smoothing roller 25 formed in a roller shape is provided. The developing solution surface smoothing roller 25 may be rotated in either direction, and by rotating it in one direction, the developing solution surface passing over the pre-developing area 6 of the split developing roller 18 can be smoothed. Other configurations are the same as those in FIG.

According to the copying machine configured as described above,
Since the developing solution surface smoothing roller 25 has a roller structure, the smoothness of the developing solution surface can be increased. Further, by changing the rotation speed, it is possible to finely adjust the amount of the developing solution on the developing roller without changing the rotation speed of the split developing roller 18.

[Fourteenth Embodiment] FIG.
FIG. 14 is a schematic configuration diagram of the copying machine according to FIG. In the fourteenth embodiment, FIG.
A cleaning blade 26 is disposed in contact with the developer surface smoothing roller 25 shown in FIG. The cleaning blade 26 is provided when the developer surface smoothing roller 25 is rotating in the same direction as the developing roller 3. Other configurations are the same as those in FIG.

According to the copying machine configured as described above,
The cleaning blade 26 can prevent the developing solution that has circulated around the developing solution surface smoothing roller 25 from coming into contact with the developing solution surface again, so that the smoothness of the developing solution surface is increased and the developing solution that has adhered to the developing solution surface smoothing roller 25 is further improved. Alternatively, since toner stains and the like can be removed, the effect of the developer surface smoothing roller 25 can be stabilized.

[Fifteenth Embodiment] FIG. 15 shows a fifteenth embodiment.
It is a schematic block diagram of the copying machine which concerns on this, and shows the same part as FIG. 10 by the same code | symbol. In this Embodiment 15, FIG.
As the developer surface smoothing means 24, a blade-shaped developer surface smoothing blade 27 is provided. The developer surface smoothing blade 27 can smooth the surface of the developer passing over the pre-development area 6. Other configurations are the same as those in FIG.

According to the copying machine configured as described above,
Since the developer surface smoothing means 24 has a blade structure, the smoothness of the developer surface can be increased. Further, the structure is simpler than that of the roller structure shown in FIG. Furthermore, by adjusting the amount of protrusion to the split developing roller 18, the amount of developer can be finely adjusted without changing the rotation speed of the split developing roller 18.

[Sixteenth Embodiment] FIG. 16 shows a sixteenth embodiment.
It is a schematic block diagram of the copying machine which concerns on this, and shows the same part as FIG. 10 by the same code | symbol. In the sixteenth embodiment, the counter electrode 28 made of metal is provided in the pre-development area 6.
The counter electrode 28 is disposed so as to face the split developing roller 18, is connected to the ground, and is disposed in contact or non-contact with the developing solution (non-contact in FIG. 16). The counter electrode 28 is for increasing the strength of the electric field formed by the split developing roller 18, and the strength of the electric field increases as the grounded counter electrode 28 is brought closer to the conductor region of the split developing roller 18. . The counter electrode 28 may have a flat plate shape, but a larger effect can be obtained if the counter electrode 28 has a shape that matches the curvature of the developer surface adhering to the split developing roller 18, as shown in the figure. (Hereinafter, margin)

According to the copying machine configured as described above,
Since the opposing electrode 28 increases the strength of the electric field formed in the pre-developing region 6 by the split developing roller 18, the effect of attracting the toner particles to the developer surface can be further enhanced. Therefore, the electrostatic latent image can be developed more efficiently.

[Seventeenth Embodiment] FIG. 17 shows a seventeenth embodiment.
It is a schematic block diagram of the copying machine which concerns on this, and shows the same part as FIG. 10 by the same code | symbol. In this Embodiment 17, FIG.
The divided developing roller 21 shown in FIG.
A ring-shaped electrode 22 for supplying a voltage to one predetermined conductor region from the outside is used. The ring-shaped electrode 22 is supported so as to contact one end of the rotating split developing roller 21 and not rotate together with the split developing roller 21. The ring-shaped electrode 22 is divided into an electrically insulated electrode portion 29a and an electrode portion 30b as shown in the figure. A voltage that acts in a direction of separating the toner particles in the developing solution from the split developing roller 21 is applied to the electrode portion 29a from the power source 10a, and a normal developing bias voltage is applied to the electrode portion 30a from the power source 10b. When a predetermined voltage is applied to each electrode, the ring-shaped electrode 2 that is in contact with each conductor region of the rotating split developing roller 21 at that time is applied.
A voltage corresponding to the potential of 2 is applied. In FIG. 17, a region 29 indicates a set of conductor regions in contact with the electrode part 29a, and a region 30 indicates a set of conductor regions in contact with the electrode part 30a.

According to the copying machine configured as described above,
In the area 29 existing in the pre-development area 6, a voltage acting in the direction of separating the toner particles from the split developing roller 21
By applying a normal developing bias voltage to the other regions 30, the toner particles of the developer passing through the pre-developing region 6 are separated by the action of the electric field generated between the regions 29 and 30. Since the toner particles can be moved in a direction away from 21, it is possible to obtain a concentration distribution in which the toner particles are attracted to the developer surface. Therefore, the electrostatic latent image can be efficiently developed.

[Embodiment 18] FIG.
It is a schematic block diagram of the copying machine which concerns on this, and shows the same part as FIG. 17 with the same code | symbol. In the eighteenth embodiment, the ring-shaped electrode 34 includes the electrode portion 31a, the electrode portion 32a, and the electrode portion 33.
It is divided into a and is configured so that different voltages are applied to each. Other configurations are the same as those in FIG. A voltage that acts in the direction of separating the toner particles in the developing solution from the split developing roller 21 is applied to the electrode portion 31a from the power source 10a, and a normal developing bias voltage is applied to the electrode portion 32a from the power source 10b. Also, the electrode part 3
A voltage that acts in the direction of attracting the toner particles in the developing solution to the split developing roller side is applied to 3a from the power supply 10c. When the toner particles have a negative charge, a positive voltage is applied to the electrode portion 33a as shown in the figure, but a ground connection may be used. When a predetermined voltage is applied to each electrode, the ring-shaped electrode 3 that is in contact with each conductor region of the rotating split developing roller 21 at that time is applied.
A voltage corresponding to the potential of 4 is applied. In FIG. 18, a region 31 is a set of conductor regions in contact with the electrode part 31a, a region 32 is a set of conductor regions in contact with the electrode part 32a, and a region 33 is a set of conductor regions in contact with the electrode part 33a. Shows.

According to the copying machine configured as described above,
In addition to the effect of the seventeenth embodiment, since an electric field that acts in the direction of attracting the toner particles to the developing roller can be formed on the conductor region 33 existing in the developer pool 5, more toner particles can be formed. Can be efficiently conveyed to the development gap region 7.

According to the wet type developing device of the present invention, the toner particles in the developer passing through the pre-developing region move in the direction away from the developing roller by the action of the electric field by the electric field forming means. The density of toner particles in the vicinity of the surface of the latent image carrier of the developing solution entering the developing gap area sandwiched between the developing roller and the latent image carrier is higher than the density of toner particles in other parts. Therefore, at the time of development, it is possible to obtain the same effect as that obtained by developing with a high-concentration developing solution, and it is possible to obtain a predetermined image density in a short time. In this case, since it is not necessary to unnecessarily increase the toner concentration of the developing solution, it is possible to minimize the amount of toner particles that aggregate or adhere in the developing solution reservoir.

In particular, according to the wet developing device of the second aspect, the toner particles are moved in the direction away from the developing roller by the action of the electric field generated between the fixed electrode and the developing roller, though the structure is simple. As a result, the toner particle density of the developer near the surface of the latent image carrier can be increased, so that a predetermined image density can be obtained in a short time.

In particular, according to the wet developing device of the third aspect, the toner is prevented from adhering to the fixed electrode. Therefore, the gap between the developing roller and the fixed electrode is not blocked by the toner adhering, and the toner is always stable. Electric field formation can be performed.

Further, according to the wet type developing device of the fourth aspect, since the developing solution surface on the developing roller is smoothed by the solution leveling means, the concentration distribution of the toner particles attracted to the developing solution surface side is uniform. Can be

Particularly, according to the wet type developing device of the fifth aspect, since the liquid level smoothing roller or the blade is used as the liquid level smoothing means, the rotation speed of the liquid level smoothing roller or the protruding amount of the blade is changed. The amount of developer on the developing roller can be finely adjusted.

Particularly, according to the wet type developing device of the sixth aspect, the developer or toner particles attached to the liquid surface smoothing roller are removed by the cleaning blade provided in contact with the liquid surface smoothing roller. The effect of the liquid surface smoothing roller can be stabilized.

Further, according to the wet developing apparatus of the seventh aspect, in particular, the roller electrodes provided in the pre-developing area can make the toner particles have a concentration distribution attracted to the surface of the developing solution. Moreover, since the roller electrode has a roller structure,
Since the smoothness of the developer surface can be increased at the same time as the effect of attracting the toner particles to the developer surface side, the concentration distribution of the toner particles attracted to the developer surface side can be made uniform.

Particularly, according to the wet type developing apparatus of claim 8,
A cleaning blade provided in contact with the roller electrode can remove the developer or toner particles attached to the roller electrode.

Further, according to the wet developing apparatus of the ninth aspect, when a voltage is applied to a predetermined conductor area of the division developing roller, the toner particles are divided by the action of the electric field generated between the conductor areas. Since the density of toner particles in the vicinity of the surface of the latent image carrier of the developer can be increased by moving the developer away from the toner image, a predetermined image density can be obtained in a short time. Further, since each conductor area of the split developing roller is electrically insulated by the insulating layer, by applying an appropriate voltage having a different value to each area,
Different areas of toner particle density can be formed. Therefore, fine control of the toner particles can be performed by appropriately selecting the region to which the voltage is applied as necessary.

In particular, according to the wet developing device of the tenth aspect, since the split developing roller is radially split from the center of the rotating shaft, the voltage is selectively applied to a predetermined conductor region of the split developing roller. This makes it possible to easily set the electric field region for attracting the toner particles to the developer surface side. Further, since no extra space is required for installing the electric field forming means, it is possible to save space.

Further, according to the wet developing apparatus of the eleventh aspect, the smoothness of the developing solution surface on the dividing developing roller can be increased by the liquid level smoothing means provided on the dividing developing roller. It is possible to make the concentration distribution of the toner particles attracted to the surface side uniform.

In particular, according to the wet developing device of the twelfth aspect, the smoothness of the developer surface on the split developing roller can be increased by the liquid level smoothing roller or the blade arranged adjacent to the split developing roller. Further, the amount of the developing solution on the developing roller can be finely adjusted by changing the rotation speed of the liquid level smoothing roller or the protruding amount of the blade.

Particularly, according to the wet developing device of the thirteenth aspect, the developing solution or toner particles attached to the liquid surface smoothing roller are removed by the cleaning blade provided in contact with the liquid surface smoothing roller. The effect of the liquid surface smoothing roller can be stabilized.

In particular, according to the wet developing device of the fourteenth aspect, the electric field strength formed by the split developing roller can be increased by the counter electrode provided so as to face the split developing roller. Can be developed more efficiently.

Further, according to the wet developing apparatus of the fifteenth aspect, a voltage acting in a direction of separating the toner particles from the developing roller is applied to the conductor area existing in the pre-developing area.
When a normal developing bias voltage is applied to the other conductor areas, the toner particles can be attracted to the developer surface side by the action of the electric field generated between these areas.
The electrostatic latent image can be efficiently developed.

In particular, according to the wet type developing apparatus of the sixteenth aspect, an electric field acting in the direction of attracting the toner particles to the developing roller can be formed on the conductive material region existing in the developing solution reservoir portion. It becomes possible to efficiently convey many toner particles to the development gap region.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a copying machine according to a first embodiment.

FIG. 2 is a schematic configuration diagram of a copying machine according to a second embodiment.

FIG. 3 is a schematic configuration diagram of a copying machine according to a third embodiment.

FIG. 4 is a schematic configuration diagram of a copying machine according to a fourth embodiment.

FIG. 5 is a schematic configuration diagram of a copying machine according to a fifth embodiment.

FIG. 6 is a schematic configuration diagram of a copying machine according to a sixth embodiment.

FIG. 7 is a schematic configuration diagram of a copying machine according to a seventh embodiment.

FIG. 8 is a schematic configuration diagram of a copying machine according to an eighth embodiment.

FIG. 9 is a schematic configuration diagram of a copying machine according to a ninth embodiment.

FIG. 10 is a schematic configuration diagram of a copying machine according to a tenth embodiment.

FIG. 11 is a conceptual perspective view of a split developing roller according to an eleventh embodiment.

FIG. 12 is a schematic configuration diagram of a copying machine according to a twelfth embodiment.

FIG. 13 is a schematic configuration diagram of a copying machine according to a thirteenth embodiment.

FIG. 14 is a schematic configuration diagram of a copying machine according to a fourteenth embodiment.

FIG. 15 is a schematic configuration diagram of a copying machine according to a fifteenth embodiment.

FIG. 16 is a schematic configuration diagram of a copying machine according to a sixteenth embodiment.

FIG. 17 is a schematic configuration diagram of a copying machine according to a seventeenth embodiment.

FIG. 18 is a schematic configuration diagram of a copying machine according to an eighteenth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor drum 2 Wet developing device 3 Developing roller 4 Scraper 5 Developer pool 6 Pre-developing area 7 Developing gap area 8 Electric field forming means 9 Fixed electrode 12, 24 Developer level smoothing means 13, 25 Developer level smoothing roller 14 , 26 cleaning blades 15, 27 developing liquid surface smoothing blades 16 roller electrodes 18, 21 split developing rollers 28 counter electrodes

Claims (16)

[Claims] 1. The electrostatic latent image is developed by forming an electrostatic latent image on the surface of a latent image bearing member and transporting a developing solution from a developer pool to a surface of the latent image bearing member by a developing roller. In the wet type developing device, an electric field is formed so that the toner particles in the developer move in the direction away from the developing roller on the area where the developer is transported from the developer pool to the surface of the latent image carrier. A wet developing device comprising means. 2. The invention according to claim 1, wherein a fixed electrode facing the developing roller is used as the electric field forming means, and the fixed electrode is required to attract the toner particles in the developing solution to the fixed electrode side. A wet developing device characterized by applying a voltage. 3. The wet developing apparatus according to claim 2, wherein the fixed electrode is arranged so as not to contact a developing solution. 4. The liquid level smoothing means for smoothing the surface of the developing solution on the developing roller before the developing solution passes through a region sandwiched between the developing roller and the fixed electrode. A wet developing device characterized by being provided. 5. The liquid level smoothing means according to claim 4, wherein a liquid level smoothing roller arranged adjacent to the developing roller or a blade arranged adjacent to the developing roller is used as the liquid level smoothing means. Wet developing device. 6. A wet developing apparatus according to claim 5, further comprising a cleaning blade provided in contact with the liquid surface smoothing roller. 7. The invention according to claim 1, wherein a roller electrode arranged opposite to the developing roller is used as the electric field forming means, and the toner particles in the developing solution are attracted to the roller electrode toward the roller electrode. A wet developing device characterized by applying a required voltage. 8. The wet developing device according to claim 7, further comprising a cleaning blade provided in contact with the roller electrode. 9. The split developing roller according to claim 1, wherein said electric field forming means has a structure in which a conductor region is divided into a plurality of portions, and each conductor region is electrically insulated by an insulating layer. A wet developing device characterized in that a voltage having a different value is applied to each conductor region of the divided developing roller. 10. The split developing roller according to claim 9, wherein the conductor region is radially divided from the rotation center axis of the roller in a cross section in a direction orthogonal to the rotation axis of the split development roller, and The wet developing device is characterized in that the conductor region of is electrically insulated by an insulating layer. 11. The wet developing device according to claim 9, further comprising a liquid level smoothing unit for smoothing the surface of the developer on the split developing roller. 12. The liquid level smoothing means according to claim 11, wherein a liquid level smoothing roller disposed adjacent to the split developing roller or a blade disposed adjacent to the split developing roller is used. A wet developing device characterized in that 13. The wet developing device according to claim 12, further comprising a cleaning blade provided in contact with the liquid surface smoothing roller. 14. A wet developing apparatus according to claim 9, further comprising a counter electrode arranged to face the split developing roller. 15. The invention according to claim 9, wherein toner particles in the developing solution are transferred from the split developing roller to a conductor region existing in a region where the developing solution is conveyed from the developer pool to the surface of the latent image carrier. A wet developing device characterized in that a voltage acting in a direction of separating is applied and a normal developing bias voltage is applied to the other conductor regions. 16. The conductor according to claim 9, wherein a normal developing bias voltage is applied to a conductor region existing in a region sandwiched between the divided developing roller and the latent image carrier, and a conductor existing in a developer pool. In the area, a voltage that acts in the direction of attracting the toner particles in the developer toward the split developing roller is developed, and in the conductor area existing in the area that conveys the developer from the developer reservoir to the surface of the latent image carrier, the development is performed. A wet developing device characterized in that a voltage is applied to each of the toner particles in the liquid so as to separate the toner particles from the developing roller.