JP2001083806A - Wet system electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wet system electrophotographic device provided with excellent transfer characteristic, being free from irregularities in an image. SOLUTION: As for the wet system electrophotographic device applying press transfer system, the device makes irregularities in an image at the time of drying in the post processing stage prevented, by means of setting toner particles in the visual image formed by a developing device 4-1 by setting toner particles by a set charger 10 and at the same time, by making the liquid developer surface forming the visual image disturbed by air evolved from a blowing nozzle 14, the device makes evaporation of carriers liquid in the liquid developer accelerated, and the transfer property improved by surely letting the visual image to be further dried.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a wet electrophotographic apparatus.

[0002]

2. Description of the Related Art A wet electrophotographic apparatus using liquid development is
It has advantages that cannot be realized with a dry electrophotographic device,
In recent years, its value is being reviewed. The use of extremely fine sub-micron toner enables high image quality to be achieved, and a sufficient amount of image density can be obtained with a small amount of toner, resulting in the economical realization of texture equivalent to offset printing. This is an advantage of a wet type electrophotographic apparatus using the same.

On the other hand, wet electrophotography using liquid toner has several problems.

As one of these problems, there is a problem relating to a transfer technique.

In the method of transferring a visible image developed from an electrostatic latent image, a visible image formed of a carrier liquid in a liquid developer and toner particles for forming a visible image is transferred to a transfer medium by electrophoresis. And a method in which a visible image composed of toner particles from which a carrier liquid has been removed is brought into contact with a transfer medium and pressure-transferred to the transfer medium using the adhesive force of the toner particles.

[0006] The transfer method for performing electrophoresis has a problem that an image is disturbed during electrophoresis.

On the other hand, in the pressure transfer system, if the carrier liquid is not sufficiently removed, the transfer efficiency of the toner particles for forming an image to the intermediate transfer member cannot be improved. In other words, if the carrier liquid remains in the image area, the portion where the carrier liquid remains remains on the latent image holding member, and a transfer loss occurs in the image on the intermediate transfer member. For this reason, it is desired to remove as much as possible the carrier liquid contained in the liquid developer for forming an image before performing the transfer step.

On the other hand, according to “Basics and Application of Electrophotographic Technology (Corona Publishing Company: First Edition in 1998)”, air is blown almost perpendicularly to a latent image holding member by restricting excess carrier liquid. A method of limiting the thickness of the excess carrier liquid is disclosed.

However, in this method, the carrier liquid has not yet been sufficiently removed, resulting in poor transfer.

Further, the developed toner particles receive a large electrostatic force in the developing area and adhere to the surface of the electrostatic latent image holding member. There is a problem that it becomes difficult to give an adhesive force, and an image is disturbed by the influence of air.

[0011]

As described above, the conventional wet electrophotographic apparatus employing the pressure transfer method has a problem in transfer characteristics because the carrier liquid is not sufficiently removed. When air is blown on the latent image holding member, there is a problem that an image is disturbed when the carrier liquid is removed.

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and promotes the evaporation of a carrier liquid to more surely remove the carrier liquid, and does not cause an image disturbance when the carrier liquid is removed. An object is to provide a wet electrophotographic apparatus.

[0013]

SUMMARY OF THE INVENTION The present invention provides a latent image carrier, a latent image forming means for forming an electrostatic latent image on the surface of the latent image carrier, and a carrier liquid and a carrier liquid on the surface of the latent image carrier. Developing means for supplying a liquid developer composed of toner particles and visualizing the electrostatic latent image, and directing toner particles in the liquid developer forming the visible image toward the latent image holding member; Setting means for forming a predetermined electric field to be moved on the surface of the latent image holding member; and liquid developing for forming the visible image so as to disturb the liquid surface of the liquid developer after applying the predetermined electric field. A wet electrophotographic apparatus comprising: a blower for supplying a gas to a liquid surface of an agent; and a transfer unit for pressure-transferring the visible image to a transfer medium after supplying the gas.

That is, by blowing air to the latent image holding member so as to disturb the liquid developer liquid surface on the surface of the latent image holding member on which the visible image is formed, the evaporation of the carrier liquid is promoted, and the setting means is used. By fixing toner particles that form a visible image to the surface of the latent image holding member, disturbance of the visible image composed of the toner particles when the liquid surface of the liquid developer is disturbed is prevented.

Further, according to the present invention, a set roller to which a predetermined voltage is applied and which is arranged in close proximity to the latent image holding member is used as the setting means, and turbulence is generated as the blowing means. The apparatus further includes a wet electrophotographic apparatus which is arranged so as to supply a gas toward the opposed portion of the set roller and the latent image holding member, and which disturbs the liquid surface by the turbulence.

As described above, by using the set roller disposed in close proximity to the latent image holding member as the setting means, and causing turbulence using this set roller, a mechanism for separately generating turbulence in the blowing means is provided. It is not necessary, and the liquid level of the liquid developer can be easily disturbed.

Further, the set roller includes a wet electrophotographic apparatus having a heating means made of an elastic material and evaporating a carrier liquid adhered to the set roller.

With this configuration, the carrier liquid on the surface of the latent image holding member on which the visible image is formed can be more reliably removed.

Further, according to the present invention, as the blowing means, a blowing port for blowing air toward the latent image holding member;
And a gap forming member which forms a gap between the latent image holding member and the latent image holding member by gas blown out from the blowing port.

That is, by supplying air to the gap between the gap forming member such as an elastic thin plate and the latent image holding member, the liquid developer liquid surface of the latent image holding member can be disturbed.

The present invention also includes a wet electrophotographic apparatus having a blowing means having a plurality of divided air outlets.

By providing a plurality of air outlets of the blowing means, a pressure distribution is generated in the air supplied to the liquid developer surface on the latent image holding member, and the developer surface can be disturbed.

Further, it is preferable that the blowing means supplies a gas having a temperature lower than the glass transition point of the toner particles. By setting the temperature of the air to be equal to or lower than the glass transition point, the toner particles can be prevented from becoming rubbery, and transferability can be improved.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic view showing a first embodiment of a wet electrophotographic apparatus according to the present invention.

The latent image carrier 1 is a photosensitive drum in which an organic or amorphous silicon photosensitive layer is provided on a conductive substrate. This latent image holding member 1 is uniformly charged by a charger 2-1 such as a well-known corona charger or scorotron charger, and then receives an exposure 3-1 by an image-modulated laser beam to form an electrostatic latent on the surface. An image is formed. Thereafter, the electrostatic latent image is visualized by the developing device 4-1 containing the liquid developer including the carrier liquid and the toner particles. Thereafter, the excess liquid developer is removed by the squeeze device 5-1.

The visible image composed of the toner particles adhered to the surface of the latent image carrier 1 according to the electrostatic latent image is fixed to the latent image carrier 1 by the setting means as it is.

The setting means forms an electric field for causing the toner particles in the liquid developer to electrophores toward the latent image holding member 1, and is provided with a set charger 1 such as an ion generator.
A set roller 13 having an electrode to which 0 or a predetermined voltage is applied may be disposed close to the electrostatic latent image. By setting the toner particles in this manner, that is, by sufficiently pressing and fixing the toner particles to the latent image holding member 1, the visible image is disturbed by disturbance generated on the liquid developer liquid surface described later. Disappears.

The visible image set by the setting means is
The carrier liquid is almost completely removed by the drying means.

The drying means according to the present invention has an air blowing means such as a blowing nozzle 14, and the air (air) generated from the air blowing means becomes turbulent and becomes a liquid developer liquid on the latent image holding member. Served on the surface. In the wet electrophotographic apparatus shown in FIG. 1, a blowing unit is provided at a position where air is blown from the downstream side in the rotation direction of the latent image holding member toward the facing portion between the set roller 13 and the latent image holding member 1. The blown blast is
The turbulent flow hits the set roller 13 and the latent image holding member 1, and the turbulent flow disturbs the liquid developer liquid level on the surface of the latent image holding member 1. By disturbing the liquid developer liquid surface in this manner, it is possible to promote the evaporation of the carrier liquid in the liquid developer on the surface of the latent image holding member 1 and, consequently, to form the liquid developer formed on the latent image holding member surface. It is possible to dry the visual image more reliably.

Here, it is preferable that the temperature of the air sent from the blowing nozzle 14 is lower than the glass transition point of the toner particles. When the toner particles are heated to a temperature higher than the glass transition point, the toner particles are transformed into a rubbery state, and there is a possibility that the transfer efficiency from the intermediate transfer medium 7 to the recording paper 9 in the transfer device 6 described below may be reduced. In consideration of the normal glass transition point of the toner particles, it is preferable to adjust the temperature of the air so that the temperature is about 5 ° C. to 30 ° C. and send the air.

The dried visible image on the surface of the latent image carrier 1 is
Thereafter, the image may be transferred to a recording medium such as a sheet 9 by the transfer unit 6, but here, the second charger 2-2 continues.
And a second laser exposure 3-2 to form a second electrostatic latent image, and to store a second developer of a color different from the liquid developer stored in the first developing device 4-1. This is developed by the second developing device 4-2, and excess developer is removed by the second squeezing device 5-2. Therefore, after the second development, a visible image of two colors is formed on the latent image holding member 1. Similarly, third and fourth developments are performed, and a full-color visible image is formed on the latent image holding member 1, and then transferred to the sheet 9 by the transfer unit 6.

The transfer means 6 comprises an intermediate transfer roller 7 arranged in pressure contact with the latent image holding member 1 and a pressure roller arranged in pressure contact with the intermediate transfer roller 7. In the primary transfer from the body 1 to the intermediate transfer medium 7 and in the secondary transfer from the intermediate transfer medium 7 to the paper 9, the transfer is performed by pressure (pressure and heat as necessary). In particular, in the stage of performing the primary transfer, the transfer efficiency to the intermediate transfer medium 7 is reduced unless the carrier liquid in the visible image is sufficiently removed. Therefore, it is important that the visible image is sufficiently dried by the drying means.

Further, in order to fix the visible image on the sheet 9, heat fixing can be performed by heating the pressure roller 8 and the like.

FIG. 2 is a partially enlarged view of the wet electrophotographic apparatus shown in FIG.

The set roller 12 has a surface made of an elastic conductive material, and a predetermined voltage as described above is applied to this surface via a contact 15. Further, the set roller 12 is disposed in contact with the latent image holding member 1 and is rotatably disposed at the same speed as the latent image holding member.

After passing through the set roller 12, the carrier liquid in the liquid developer for forming a visible image is evaporated and removed by the drying means. It is possible to remove the carrier liquid in advance and reduce the amount of the carrier liquid to be removed by the drying means.

For example, by using a silicon-based material having a high water-absorbing property for the carrier liquid as the surface material of the set roller 12, it becomes possible to absorb the carrier component from the liquid developer on the surface of the latent image holding member 1. On the other hand, a similar effect can be obtained by forming a roller with a material having a low water absorption for a carrier liquid such as urethane rubber or fluorine rubber and removing the carrier liquid attached to the roller with a blade (not shown). it can. Since the predetermined voltage is applied to the set roller, the toner particles in the liquid developer do not adhere to the set roller.

Further, by disposing a heater 13 for heating the set roller having absorbed the carrier liquid, the carrier liquid absorbed by the set roller 12 can be removed by evaporation. At this time, it is desirable to adjust the heater so that the temperature of the heated set roller 12 becomes lower than the glass transition point of the toner particles. If the surface temperature of the set roller is too high, the toner particles adhering to the surface of the latent image holding member may be rubberized. When the toner particles are rubberized, there is a possibility that the transfer from the intermediate transfer medium to the recording paper cannot be performed.

In the first embodiment, the visible image is more reliably set by providing the set charger 10 in addition to the set roller 12. However, a set charger is not always necessary.

FIGS. 3 and 4 show a modification of the first embodiment.

As shown in FIG. 3, by providing an enclosing portion 18 for the set roller 12 so as not to block the air 17 blown from the blowing nozzle 14, the carrier liquid vapor and the carrier liquid can be prevented from being scattered. Enclosure 1
8 is provided with a structure 19 for collecting the carrier liquid vapor, and by doing so, unnecessary diffusion of the carrier liquid vapor and the carrier liquid can be prevented.

The carrier liquid that could not be removed by the final squeeze roller (not shown)
2 There is a possibility of accumulation on the upstream side. Therefore, in FIG. 4, the carrier liquid removing blade 20 and the excess carrier liquid container 21 are arranged on the upstream side of the set roller 12 in a non-contact state with the latent image holding member 1 in order to collect the excess carrier liquid. With this configuration, the surplus carrier liquid does not always contact the elastic roller 12 on the latent image holding member surface 1, and the carrier liquid can be removed from the developed image on the downstream side of the elastic roller 12. it can.

FIG. 5 is a view showing a second embodiment of the wet electrophotographic apparatus of the present invention.

The process up to the setting means is as follows.
This is performed in the same manner as in the embodiment. First, a liquid developed image is formed on the latent image holder 1, and a set charger 10 for setting the developed image on the latent image holder 1 is disposed downstream of the squeeze roller means.

After toner particles for forming a visible image on the latent image holding member 1 are fixed, air is blown to the latent image holding member 1 downstream of the set charger 10 by a blowing means such as an air blowing nozzle 14. At this time, the latent image holding member 1 is provided upstream or downstream of the blowing nozzle 14 using the air force of the blowing air.
The elastic thin plates 31A (upstream side) and 31B (downstream side) capable of forming a slight gap are arranged. These elastic thin plates have the effect of forming a slight gap with the latent image holding member 1 by air force floating and disturbing the surface of the carrier liquid remaining on the latent image holding member 1. Thereby, the liquid level of the liquid developer on the surface of the latent image holding member is disturbed, and the evaporation of the carrier liquid in the developed image can be promoted.

At this time, as described above, it is also important that the discharge temperature on the latent image holding member 1 be lower than the glass transition point.

FIG. 6 shows a modification of the second embodiment. As described above, in order to obtain the effect of promoting the evaporation of the carrier liquid,
An elastic thin plate 31A that can form a slight gap with the latent image holding member 1 by using the air force of the blown air on the upstream or downstream side of the blowout nozzle portion 14 and the air blowout port 14.
(Upstream gap forming section) and 31B (downstream gap forming section). Further, in order to prevent the carrier liquid and the carrier liquid vapor from being scattered by the blown air 17, an enclosure 32 is provided. By adopting such a configuration, the diffusion of the surplus carrier liquid vapor or the like can be prevented.

FIG. 7 shows a modification of the second embodiment of the present invention. As described above, in order to obtain the effect of accelerating the evaporation of the carrier liquid, a slight gap with the latent image holding member 1 can be formed on the upstream or downstream side of the blowing nozzle portion 14 and the air blowing nozzle 14 by using the pressure of the blowing air. Elastic thin plates 31A (upstream side) and 31B (downstream side) are provided.
Excess carrier liquid in the developed image is blocked by the blown air 17, and a backflow phenomenon may occur on the set charger 10 side, which is upstream of the latent image holding member 1. At the same time that the backflow occurs, the excess carrier liquid always remains in the place where it is blocked, and the effect of removing the carrier liquid by the blowing air 17 is reduced. In order to remove the blocked excess carrier liquid, in FIG. 7, the excess carrier liquid removal blade 33 disposed with a small gap from the latent image holding member 1 and the excess carrier liquid blade 33 collects the excess carrier liquid. Carrier liquid collecting container 34 for storing the used carrier liquid
And are arranged.

Next, a third embodiment of the present invention will be described with reference to FIG.

FIG. 8 is a cross-sectional view when the wet electrophotographic apparatus shown in FIG. 6 is provided with a carrier liquid suction means and cut along AA '.

The blowing nozzle 14 serving as a blowing means is divided into a plurality of blowing ports by a partition plate 41 which is arranged to be inclined from the center of the latent image holding member toward the end.

As described above, by providing the blowing means having the divided outlets, a pressure distribution is generated by the blowing in the liquid developer on the surface of the latent image holding member, and the liquid surface of the liquid developer is disturbed. be able to.

Further, since the partition plate 41 is provided so as to be inclined from the central portion of the latent image holding member toward the end portion, a part of the carrier liquid can be sent to the end portion of the latent image holding member to be removed.
The removed carrier liquid and carrier liquid vapor are sucked by suction nozzles 43 arranged on both side surfaces (width direction). After the suction, the carrier liquid vapor is converted into the carrier liquid by the carrier liquid vapor liquefying means 44 using a condensation phenomenon in which a fine mesh structure and a cold air pipe are prepared, and stored in the solvent recovery unit 46. Here, the blower 45 is also used for air discharge and suction, but the discharge side and the suction side may be individually arranged.

[0055]

As described above, according to the present invention,
The carrier liquid contained in the developed image can be completely removed from the latent image holding member without disturbing the image, and only the toner image can be fixed on the latent image holding member. Further, by disturbing the surface of the liquid developer on the latent image holding member, evaporation of the carrier liquid is promoted, and the transfer characteristics of the visible image can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a first embodiment of a wet electrophotographic apparatus according to the present invention.

FIG. 2 is a partially enlarged view of the wet electrophotographic apparatus shown in FIG.

FIG. 3 is a view showing a modification of the wet electrophotographic apparatus shown in the first embodiment.

FIG. 4 is a view showing another modification of the wet electrophotographic apparatus shown in the first embodiment.

FIG. 5 is a schematic view showing a second embodiment of the wet electrophotographic apparatus of the present invention.

FIG. 6 is a view showing a modification of the wet electrophotographic apparatus shown in the second embodiment.

FIG. 7 is a view showing another modification of the wet electrophotographic apparatus shown in the second embodiment.

FIG. 8 is a schematic view showing a third embodiment of the wet electrophotographic apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Latent image holding body 2 ... Charger 3 ... Laser exposure 4 ... Developing device 5 ... Squeezing means 6 ... Transfer device 7 ... Intermediate transfer medium 8 ... Addition Pressure roller 9 ... Paper 10 ... Set charger 12 ... Set roller 13 ... Heater 14,41 ... Blow-out nozzle 15 ... Contact brush 17,42 ... Blow-out air 32 ... Enclosure 19: Carrier liquid vapor recovery device 20, 33 ... Excess solvent removal blade 21, 34, 46 ... Excess solvent recovery container 31 ... Thin elastic plate 43 ... Suction nozzle 44 ..Liquefaction means

Claims (6)

[Claims] 1. A latent image carrier, a latent image forming means for forming an electrostatic latent image on the surface of the latent image carrier, and a liquid developer comprising a carrier liquid and toner particles on the surface of the latent image carrier. Developing means for visualizing the electrostatic latent image, and a predetermined electric field for moving toner particles in a liquid developer forming the visible image toward the latent image holding member, Setting means for forming on the surface of the latent image holding member; supplying the gas to the liquid surface of the liquid developer for forming the visible image so as to disturb the liquid surface of the liquid developer after applying the predetermined electric field; A wet electrophotographic apparatus, comprising: a blowing means for supplying a gas; and a transfer means for performing pressure transfer to a transfer medium after supplying gas. 2. The image forming apparatus according to claim 1, wherein the setting unit is a set roller disposed in close proximity to the latent image holding member, and the blowing unit is configured to generate a turbulent flow of the set roller and the latent image holding member. The wet electrophotographic apparatus according to claim 1, wherein the liquid surface is arranged so as to supply gas toward the facing portion, and the turbulent flow disturbs the liquid surface. 3. A wet electrophotographic apparatus according to claim 2, wherein said set roller is made of an elastic material, and has heating means for evaporating a carrier liquid attached to said set roller. 4. A gap forming member for forming a gap between a blowing port for supplying gas toward the latent image holding member and a gas blown from the blowing port. 2. The wet electrophotographic apparatus according to claim 1, comprising: 5. The wet electrophotographic apparatus according to claim 1, wherein said blowing means has a plurality of divided outlets. 6. The wet electrophotographic apparatus according to claim 1, wherein said blowing means supplies gas having a temperature lower than the glass transition point of the toner particles.