JP2002108108A - Wet developing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the aggregation of toner particles of a wet developing apparatus. SOLUTION: The wet developing apparatus has a supply roller 2 which is disposed at a prescribed interval relative to a developing roll 1, dipped into liquid toner 52 in a liquid toner storage member 53, and rotates in the same direction as the developing roll 1 to supply the liquid toner 52 to the developing roll 1, a cylindrical member 3 disposed above the developing roll 1 at a prescribed interval relative to the developing roll 1, a first electrically conductive member 4A which is disposed between the cylindrical member 3 and the developing roll 1, and comes in contact with the liquid toner 52 going towards the cylindrical member 3 from the supply roller 2 on the developing roll 1, and a second electrically conductive member 4B which is disposed oppositely to the first electrically conductive member 4A between the cylindrical member 3 and the developing roll 1, and comes in contact with the liquid toner 52 going towards an image carrier 51 from the cylindrical member 3 on the developing roll 1. The distance of the ends at the side of the developing roller 1 formed by the first conductive member 4A and the second conductive member 4B is set wider than the distance of the ends at the side of the cylindrical member 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet developing device for developing an electrostatic latent image with liquid toner.

[0002]

2. Description of the Related Art Developing apparatuses employed in image forming apparatuses are roughly classified into dry developing apparatuses and wet developing apparatuses. The wet developing device using the liquid toner has an advantage that a high resolution can be obtained because the toner particles are finer than the dry developing device using the powder toner.

A liquid toner used in a wet developing device is a toner in which charged granular toner is dispersed in a carrier liquid. When such a liquid toner is supplied to the surface of an image carrier, the toner is electrophoresed. This is attached to the electrostatic latent image to be visualized. More specifically, for example, Isopar_L (registered trademark: Ex)
A liquid toner in which a toner composed of carbon black or the like coated with a resin is dispersed in a carrier liquid made of an aliphatic hydrocarbon such as xon Corporation) is used as the surface of an image carrier on which an electrostatic latent image is formed and the surface of the image carrier. To supply the liquid toner to the surface of the image carrier, and develop the electrostatic latent image using the electrophoresis phenomenon of the charged toner in the carrier liquid. Is what you do.

Here, a conventional wet developing device will be described.

FIG. 2 is an explanatory view showing a conventional wet developing apparatus.

In FIG. 2, an image carrier 51 on which an electrostatic latent image is formed is rotatably supported by an image forming apparatus body using a conventional wet developing device. A cleaning roller and a cleaning blade (not shown) for removing the liquid toner 52 remaining on the outer peripheral surface of the image carrier 51 are provided on an outer periphery of the image carrier 51, and an electrostatic latent image charge remaining on the image carrier 51 is provided. Remover (not shown), image carrier 5
Charging device (not shown) for uniformly charging 1, image carrier 5
An exposure optical system (not shown) for forming an electrostatic latent image on the image forming apparatus 1 and a wet developing device 100 for developing the electrostatic latent image into a visible image are sequentially arranged along the rotation direction of the image carrier 51. I have.

[0007] The liquid toner 5 is provided inside the developing device 100.
2, a developing roller 101 that supplies the liquid toner 52 to the outer peripheral surface of the image carrier 51 to make the electrostatic latent image visible as a toner image, and a liquid toner storage member 53 Of the liquid toner 52 of the developing roller 10
1 and a liquid film forming unit 103 composed of a roller group provided with a predetermined distance from the developing roller 101. A liquid film forming unit 103 is provided between the supply roller 102 and the image carrier 51 in accordance with the rotation direction of the developing roller 101. Are located.

Next, the developing device 10 constructed as described above
The operation of 0 will be described below.

When image formation is started, the surface of the image carrier 51 is uniformly charged, and an electrostatic latent image is formed on the image carrier 51 by an exposure optical system.

When the supply roller 102 partially immersed in the liquid toner 52 rotates, the liquid toner 52 is supplied to the surface of the developing roller 101. The liquid toner 52 supplied to the developing roller 101 is adjusted by the liquid film forming means 103 to such an amount that an image can be formed satisfactorily, and approaches the surface of the image carrier 51 by the rotation of the developing roller 101.

When the image carrier 51 and the developing roller 101 are near the closest point, the liquid toner 52 moves from the developing roller 101 to the image carrier 51 by the electric field force of the toner moving means.

At this time, the developing roller 101 and the image carrier 5
1, the liquid toner 52 flies and moves to the image carrier 51, and a meniscus in which the developing roller 101 and the image carrier 51 are connected by the liquid toner 52 is formed. In some cases, the toner 52 moves from the developing roller 101 to the image carrier 51 by electrophoresis.

[0013]

In such a conventional wet developing apparatus, the liquid pool formed between the roller of the liquid film forming means and the developing roller is surrounded by these rollers and air. Will be. Therefore, even if a high voltage is applied to the roller, the boundary surface of the liquid toner that comes into contact with air is in a ground state. Therefore, the liquid toner having the potential moves from the roller to the boundary surface in contact with air, particularly when the two rollers have the same polarity.

When such a state is repeated, the toner particles collect on the boundary surface between the liquid pool and the air, so that a portion where the toner density is high and a portion where the toner density is low are generated in the liquid pool. When the energization is completed, the potential in the liquid pool becomes the same potential, so that the agglomerated portion of the toner particles floats in the liquid pool, and when the energization is started again, the amount of potential is increased by the aggregation, so that the toner particles are drawn toward the developing roller. As a result, density unevenness occurs.

In order to solve such a problem, it is necessary to reduce the influence of liquid toner having a low pigment concentration or residual potential.
The use of a liquid toner having a low potential is conceivable, but this is not an effective means because the print quality is degraded.

Accordingly, it is an object of the present invention to provide a wet developing device capable of preventing aggregation of toner particles.

[0017]

In order to solve this problem, a wet developing apparatus according to the present invention comprises an image carrier on which an electrostatic latent image is formed and a liquid toner comprising a toner and a carrier liquid. A developing roller for supplying a toner image thereon to form a toner image by visualizing the electrostatic latent image; a liquid toner storage member storing the liquid toner; and a liquid toner disposed at a predetermined distance from the developing roller. A supply roller immersed in the liquid toner stored in the storage member and rotating in the same direction as the developing roller to supply the liquid toner in the liquid toner storage member to the surface of the developing roller; and a developing roller above the developing roller. A cylindrical member disposed at a predetermined interval; a first conductive member disposed between the cylindrical member and the developing roller and in contact with liquid toner on the developing roller from the supply roller toward the cylindrical member; A second conductive member disposed between the cylindrical member and the developing roller so as to face the first conductive member and in contact with the liquid toner on the developing roller from the cylindrical member to the image carrier; The distance between the developing roller side end formed by the conductive member and the second conductive member is set wider than the distance between the cylindrical member side end.

Thus, when the liquid film is formed on the developing roller, the direction of the electric field is regulated without the liquid toner coming into contact with air, so that aggregation of toner particles can be prevented.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, an image bearing member on which an electrostatic latent image is formed, and a liquid toner comprising a toner and a carrier liquid are supplied onto the image bearing member to form a static image. A developing roller that visualizes the latent image to form a toner image;
The liquid toner storage member storing the liquid toner and the developing roller are disposed at a predetermined distance from the developing roller and immersed in the liquid toner stored in the liquid toner storing member, and rotate in the same direction as the developing roller to rotate the liquid. A supply roller for supplying the liquid toner in the toner storage member to the surface of the developing roller; a cylindrical member disposed above the developing roller at a predetermined distance from the developing roller; and a cylindrical member disposed between the cylindrical member and the developing roller. A first conductive member in contact with the liquid toner on the developing roller from the supply roller to the cylindrical member; and a first conductive member similarly arranged between the cylindrical member and the developing roller to face the first conductive member. A second conductive member in contact with the liquid toner on the developing roller toward the carrier; and a developing roller formed by the first conductive member and the second conductive member. A wet development apparatus towards the distance of the end portions is set wider than the distance of the cylindrical member side end portion,
When the liquid film is formed on the developing roller, the direction of the electric field is regulated without the liquid toner coming into contact with air, so that it has the effect of preventing aggregation of toner particles.

According to a second aspect of the present invention, in the first aspect, a voltage having the same potential as the cylindrical member and a different potential from the developing roller is applied to the first and second conductive members. Since the toner particles in the liquid toner supplied from the supply roller are guided to the surface of the development roller, it has an effect of improving the print density.

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

FIG. 1 is an explanatory view showing a wet developing apparatus according to an embodiment of the present invention.

In FIG. 1, an image carrier 51 on which an electrostatic latent image is formed is rotatably supported by the image forming apparatus main body. An organic photoconductor (OPC) is provided on the surface of the image carrier 51,
An amorphous silicon (a-Si) or selenium (Se) photosensitive receiving layer is applied. In the present embodiment, the image carrier 51 has a drum shape, but may have a belt shape.

A cleaning unit (not shown) provided with a cleaning roller and a cleaning blade for removing the liquid toner 52 remaining on the outer peripheral surface of the image carrier 51, a light emitting diode and the like are provided on the outer periphery of the image carrier 51. A static eliminator 55 for removing the electrostatic latent image charge remaining on the image carrier 51 after removing the residual toner by light irradiation, a charger 56 for uniformly charging the image carrier 51 using corona discharge, and a host computer. The exposure optical system 5 for turning on / off the laser based on the information of the laser beam and forming an electrostatic latent image on the image carrier 51
7. A wet developing device 100 for transferring the liquid toner 52 contributing to development to a portion of the electrostatic latent image to develop the electrostatic latent image into a visible image is sequentially arranged along the rotation direction of the image carrier 51. ing.

A liquid toner 52 is provided inside the developing device 100.
Is stored.

Further, the developing roller 1 for supplying the liquid toner 52 to the outer peripheral surface of the image carrier 51 and causing the electrostatic latent image formed on the image carrier 51 to appear as a toner image protrudes from the wet developing device. Is provided.

Further, a supply roller 2 which is partially immersed in the liquid toner 52 in the liquid toner storage member 53 and supplies the liquid toner 52 to the developing roller 1 is provided at a predetermined distance from the developing roller 1. ing. The developing roller 1 and the supply roller 2 rotate in the same direction.

A liquid film forming means 34 for adjusting the liquid toner 52 supplied from the supply roller 2 to the developing roller 1 to a predetermined film thickness to form a liquid film is provided.

The liquid film forming means 34 is disposed above the developing roller 1 at a predetermined distance from the developing roller 1, and is disposed between the cylindrical member 3 and the developing roller 1. A first conductive member 4A in contact with the liquid surface of the liquid toner 52 on the developing roller 1 from the roller 2 toward the cylindrical member 3, and also disposed between the cylindrical member 3 and the developing roller 1; And a second conductive member 4B in contact with the liquid surface of the liquid toner 52 on the developing roller 1 toward the carrier 51.

The cylindrical member 3 is set in the same direction as the rotation direction of the developing roller 1 so as to move in a relative direction in the vicinity thereof, thereby improving the efficiency of thinning. Further, the first conductive member 4A and the second conductive member 4B are disposed so as to face each other, and the distance a of the end of the developing roller 1 formed by the two members is the distance of the end of the cylindrical member 3 side. It is wider than a.

The developing roller 1 is formed of a conductive material. The developing roller 1 is connected to a power supply for applying a voltage at a level between the charging potential of the image carrier 51 and the charge extinction potential. Further, the image carrier 51 is set to the ground potential,
Therefore, when a voltage is applied to the developing roller 1 by the power supply, an electric field is formed between the developing roller 1 and the image carrier 51.

Further, the cleaning roller of the cleaning unit is formed of a sponge-like member which is in pressure contact with the image carrier 51, and the cleaning blade is also the same as the image carrier 51.
It is made of an elastic body such as rubber which is pressed against the elastic member.

The operation of the thus-configured wet developing apparatus according to the present embodiment will be described below.

When image formation is started, first, as a charging step, a corona discharge is performed by a charger 56 connected to a high-voltage power supply, so that the surface of the image carrier 51 is uniformly charged.

Next, in the exposure step, the laser of the exposure optical system 57 is turned on / off by information sent from the host computer, and the charge on the surface of the image carrier 51 rotated in the circumferential direction is partially eliminated. As a result, an electrostatic latent image is formed.
At the same time, the developing roller 1, the supply roller 2, the cylindrical member 3, the liquid toner storage member 53, and the conductive members 4A, 4B
Is applied with a voltage.

At this time, at least the cylindrical member 3 and the conductive members 4A and 4B are supplied with the same potential as each other and a voltage different from that of the developing roller 1. For example, when the charge polarity of the liquid toner 52 is positive, the cylindrical member 3 and the conductive members 4A and 4B have a higher voltage value than the developing roller 1.

The liquid toner 52 supplied to the surface of the developing roller 1 by the supply roller 2 is thinned by the cylindrical member 3 of the liquid film forming means 34. At the same time, the pigment component in the liquid pool formed between the developing roller 1 and the cylindrical member 3 is guided to the surface of the developing roller 1 by the electric force of the conductive members 4A and 4B and the cylindrical member 3 and the developing roller 1. You. Therefore, the thin film of the liquid toner 52 formed by the liquid film forming unit 34 is conveyed to the image carrier 51 as a concentrated high-concentration toner.

When a voltage is applied to the developing roller 1, an electric field is formed between the developing roller 1 and the image carrier 51. Then, as the positive charges charged on the surface of the image carrier 51 approach, the liquid toner 52 on the surface of the developing roller 1 becomes negatively charged by electrostatic induction and is attracted to the image carrier 51. In this state, when the gap between the developing roller 1 and the image carrier 51 further narrows, the surface of the liquid toner 52 rises, and the tip of the projection adheres to the image carrier 51.

Here, the voltage to the developing roller 1 is, for example, 5
If the voltage is set to about 00 V, an electric field from the developing roller 1 to the image carrier 51 is formed between the developing roller 1 and the low potential (about 100 V) image forming portion of the image carrier 51 where the charge has disappeared. Therefore, in the case of the liquid toner 52 having a positive charging polarity, the pigment component migrates and is supplied to the image forming portion of the image carrier 51 by the action of such an electric field. Further, an electric field from the image carrier 51 toward the developing roller 1 is formed between the developing roller 1 and a high-potential (about 700 V) non-image forming portion of the image carrier 51 where the charge has not disappeared. In the case of the liquid toner 52 having a positive charging polarity, the toner migrates in a direction away from the image non-forming portion of the image carrier 51 by the action of such an electric field, and is not supplied to the image non-forming portion.

Thus, the liquid toner 52 supplied to the developing roller 1 is supplied to a portion of the image carrier 51 where the electrostatic latent image is formed. Then, the electrostatic latent image formed on the image carrier 51 is exposed as a toner image.

At approximately the same time as the transfer material is conveyed to a transfer roller (not shown), the transfer roller comes into contact with the image carrier 51. Then, by applying a predetermined level of transfer bias, the toner image on the image carrier 51 is transferred to a transfer material.

On the other hand, the liquid toner 52 remaining on the image carrier 51 without being transferred to the transfer material is removed by the cleaning unit. Further, the residual electrostatic image on the image carrier 51 is neutralized by the neutralizer 55. As a result, the image carrier 51 enters a standby state for new image formation.

As described above, according to the present embodiment, when the liquid film is formed on the developing roller 1, the liquid toner 5
Since the direction of the electric field is regulated without contacting 2 with air,
Aggregation of toner particles can be prevented. As a result, the liquid toner 52 having no density unevenness can be supplied to the image carrier, and an image with good print quality can be obtained.

[0044]

As described above, according to the present invention, when the liquid film is formed on the developing roller, the direction of the electric field is regulated without the liquid toner coming into contact with air, so that the aggregation of toner particles can be prevented. An effective effect is obtained that is possible.

As a result, it is possible to supply a liquid toner having no density unevenness to the image carrier, and it is possible to obtain an effective effect that an image of good print quality can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a wet developing device according to an embodiment of the present invention;

FIG. 2 is an explanatory view showing a conventional wet developing device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 developing roller 2 supply roller 3 cylindrical member 4A first conductive member 4B second conductive member 51 image carrier 52 liquid toner 53 liquid toner storage member

Claims (2)

[Claims] An image carrier on which an electrostatic latent image is formed; and a liquid toner comprising a toner and a carrier liquid supplied onto the image carrier to visualize the electrostatic latent image to form a toner image. A developing roller, a liquid toner storage member in which the liquid toner is stored, and a liquid toner storage member disposed at a predetermined distance from the developing roller and immersed in the liquid toner stored in the liquid toner storage member, and developed. A supply roller that rotates in the same direction as a roller and supplies the liquid toner in the liquid toner storage member to the surface of the developing roller; and a predetermined distance from the developing roller above the developing roller. A first conductive member disposed between the cylindrical member and the developing roller and in contact with the liquid toner on the developing roller toward the cylindrical member from the supply roller; A second conductive member disposed between the cylindrical member and the developing roller so as to face the first conductive member and in contact with the liquid toner on the developing roller from the cylindrical member toward the image carrier; A distance between the developing roller side end formed by the first conductive member and the second conductive member is set wider than a distance between the cylindrical member side end. A wet developing device. 2. A wet developing apparatus according to claim 1, wherein a voltage having the same potential as that of said cylindrical member and a potential different from that of said developing roller is applied to said first and second conductive members. .