JPH11167295A - Wet electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently heat and melt toner transferred to an intermediate transfer body without giving a thermal influence on a photoreceptor in the case of using the intermediate transfer body and using non-volatile, high-viscosity and high concentration liquid toner. SOLUTION: In this device, the surface of the intermediate transfer body 18 is partially heated by an intermediate transfer body heating device 18 before the transfer body 15 comes into contact with a pressure roller 19. The intermediate transfer body 15 is constituted of a metallic drum, a conductive, heat- resistant elastic layer formed on the surface of the metallic drum, and a conductive, heat-resistant, releasable and silicone oil resistant surface layer. Besides, a heating belt driven by at least one heating roller is brought into contact with the intermediate transfer body at the same speed, and also, an inner heat source is installed on the rear side of the inside part of the belt so as to replenish heat energies to the heating belt whose temperature drops in accordance with the heat transfer in contact with the toner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet type electrophotographic apparatus using a non-volatile, high-viscosity, high-concentration liquid toner, and more particularly, to a method using an intermediate transfer member. The present invention relates to a wet electrophotographic apparatus capable of efficiently heating and melting toner transferred to an intermediate transfer member without affecting the toner.

[0002]

2. Description of the Related Art An electrostatic latent image is generated on a photoconductor (drum),
2. Description of the Related Art In an electrophotographic apparatus in which toner is adhered thereto and transferred to paper or the like for fixing, a dry type using powder toner is widely used.

However, the powder toner has a problem that the toner is scattered, and the toner particles have a particle size of 7 to 10 μm.
There is a problem that the resolution is poor due to the large value of m.
Therefore, when high resolution is required, a wet type using a liquid toner is used. This is because the liquid toner has toner particles as small as about 1 μm and the charge amount is large, so that disturbance of the toner image hardly occurs and high resolution can be realized.

In a conventional wet-type electrophotographic apparatus, a low-viscosity liquid toner in which a toner is mixed with an organic solvent at a ratio of 1 to 2% is used as a developing solution. However, such a developer uses an organic solvent that is harmful to the human body and uses a large amount of the organic solvent because of its low toner concentration, which has a serious problem of causing environmental problems.

[0005] Against this background, a wet type using a high-viscosity, high-concentration developer constituted by dispersing a high-concentration toner in silicone oil or the like is described in International Publication No. WO95 / 08792. An invention of an electrophotographic apparatus has been disclosed.

The use of this liquid toner has the advantages that the problem of harm to the human body does not occur, and the high toner concentration eliminates the need to use a large amount of developer.

On the other hand, as a method for fixing the toner adhered to the electrostatic latent image on the photoreceptor to a print medium, the toner adhered to the photoreceptor is transferred to an intermediate transfer member, and the intermediate transfer member is heated. A method in which the toner is melted, adhesively transferred to a print medium, and fixed, and a method in which toner attached to a photoreceptor is transferred to a print medium using an electric field without using an intermediate transfer body. There is a method in which the toner is melted and fixed by heating the print medium.

The former fixing method has an advantage that the printing medium only needs to be passed once through the intermediate transfer member, and is widely used when handling color images. On the other hand, the latter fixing method has an advantage in that heat is not transmitted to the photosensitive member because no intermediate transfer member is used, and is widely used when handling monochrome images.

Even when a high-viscosity, high-concentration liquid toner exhibiting non-volatility as described above is used, conventionally, the toner is printed according to the former fixing method in accordance with the same configuration as that used in the prior art. A method of fixing to a medium or fixing toner to a print medium according to the latter fixing method is adopted.

[0010] For example, “International Publication Number WO95 / 087
92 ", according to the latter fixing method, the toner attached to the photoreceptor is transferred to a print medium using the force of an electric field, and the toner is melted and fixed by heating the print medium. The method has been adopted.

[0011]

When a color image is handled, toner applied to a photoreceptor is transferred to a print medium by utilizing the force of an electric field, and the toner is melted by heating the print medium. If the printing method is adopted, the print medium must pass through the position of the photoreceptor at least three times (four times when black is realized by one toner), which poses a practical problem.

From now on, when handling a color image, there is a method in which the toner adhered to the photoreceptor is transferred to an intermediate transfer member, and the intermediate transfer member is heated to melt the toner and fix it on a print medium. Will be taken. When adopting a configuration in which toner is fixed on a print medium according to this method, as shown in the conventional configuration of FIG. 14, an intermediate transfer roller composed of a hollow metal drum is prepared as an intermediate transfer member, and the hollow portion is provided in the hollow portion. A configuration in which a halogen heater is disposed to heat the entire intermediate transfer body has been adopted.

However, according to this configuration, there is a problem in that the heat of the intermediate transfer body, whose surface temperature is always high, is transferred to the photoconductor, which adversely affects the photoconductor. However, when using a high-viscosity, high-concentration developer composed by dispersing a high-concentration toner in silicone oil or the like, the heat capacity of the toner decreases due to the small toner particles. Different methods of heating the intermediate transfer member are feasible, which may be able to prevent the photoconductor from being affected by heat.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is directed to a configuration using a non-volatile, high-viscosity, high-concentration liquid toner. It is an object of the present invention to provide a new wet type electrophotographic apparatus capable of efficiently heating and melting the toner transferred to the intermediate transfer member without affecting the toner.

[0015]

The image support of the present invention, that is, the photoreceptor 10 is charged by a charging device 11 and then exposed by an exposure device 12 to form an electrostatic latent image. The pre-wet device 13 applies a silicone oil having a viscosity of about 2.5 cSt to the surface of the photoconductor 10 in a thickness of 4 to 5 μm.

The developing device 14 is provided in association with yellow / magenta / cyan / black, and is biased with respect to the photosensitive member so that the toner viscosity is 400 to 4000 mPa.
In S, a non-volatile, high-viscosity, high-concentration liquid toner having a carrier viscosity of 20 cSt is used as the liquid developer. The supply of the developer is carried out by using an applicator roller and transporting the developer while thinly extending it from the toner pool. Next, the positively charged toner is supplied to the photoconductor 10 according to the electric field between the photoconductor 10 and the toner particles adhere to the exposed portion of the charged photoconductor 10.

The intermediate transfer member 15 is biased and transfers the toner adhered to the photosensitive member 10 in the order of yellow, magenta, cyan, and black in accordance with an electric field between the intermediate transfer member 15 and the photosensitive member 10. The pressure roller 19 fixes the toner of the intermediate transfer body 15 melted by the heating device 18 on the print medium. The intermediate transfer member 15 includes a metal drum, a conductive and heat-resistant elastic layer on the surface of the metal drum, and a surface having conductivity, heat resistance, peelability, and preferably silicone oil resistance. It is composed of layers.

The heating device 18 partially heats the surface of the intermediate transfer member 15 at a position before contacting the pressure roller 19. As the heating device 18, a heat belt driven by at least one heat roller is brought into contact with the intermediate transfer member at the same speed, and an internal heat source is further provided on the back side of the abdomen of the belt. It replenishes heat energy to the heat belt where the temperature drops. This heating means is configured to be heated in advance, and to be brought into contact with the intermediate transfer body 15 only when melt-transferring to a print medium.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail according to embodiments. In the present invention, a non-volatile, high-viscosity, high-concentration liquid toner is used as a liquid developer. The liquid toner is obtained by dispersing toner particles such as a pigment in a liquid carrier (oil). It is.

FIG. 1 shows the overall configuration of a wet electrophotographic apparatus provided with the present invention. As shown in FIG. 1, a wet electrophotographic apparatus according to the present invention includes a photosensitive member 10 and a charging device 11.
, An exposure device 12, a pre-wet device 13, a developing device 14, an intermediate transfer member 15, a blade 16, a charge removing device 17, a heating device 18, and a pressure roller 19.

The charging device 11 applies a voltage of about 700 V
To be charged. The exposure device 12 forms an electrostatic latent image on the photoconductor 10 by exposing the photoconductor 10 using a laser beam having a wavelength of 780 nm so that the potential of the exposed portion becomes about 100 V.

The pre-wetting device 13 applies a silicone oil having a viscosity of about 2.5 cSt to the surface of the photoreceptor 10 in a thickness of 4 to 5 μm. Here, the pre-wet apparatus 13 may execute the pre-wet processing before the exposure processing performed by the exposure apparatus 12, or may execute the pre-wet processing after the exposure processing.

The developing device 14 is provided in association with yellow / magenta / cyan / black, and is biased to about 400 V, as shown in FIG.
A toner layer having a thickness of 2 to 3 μm is formed on the developing roller 141 by transporting a liquid toner having a carrier viscosity of 20 cSt at ４4000 mPa · S while thinly extending it from the toner pool using the applicator roller 140. I do. The developing roller 141 supplies the toner, which is positively charged, to the photoconductor 10 according to the electric field between the photoconductor 10 and the developing roller 141 so that an exposed portion or an unexposed portion of the photoconductor 10 charged to about 100 V is applied. Apply toner. At this time, according to the pre-wet layer applied by the pre-wet device 13, it is possible to prevent the toner from adhering to the non-exposed portion of the photoconductor 10 as shown in FIG.

The intermediate transfer member 15 is biased to about -800 V, and the photosensitive member 1 is moved in accordance with an electric field between the intermediate transfer member 15 and the photosensitive member 10.
The toner attached to 0 is transferred. This intermediate transfer member 15
First, yellow toner adhered to the photoconductor 10 is transferred, then magenta toner adhered to the photoconductor 10 is transferred, and then cyan toner adhered to the photoconductor 10 is transferred. Then, the black toner attached to the photoconductor 10 is transferred.

The blade 16 removes toner and pre-wet liquid remaining on the photoreceptor 10. The neutralization device 17 neutralizes the photoconductor 10. The heating device 18 is used for the intermediate transfer member 15.
By heating the surface, the toner attached to the intermediate transfer member 15 is melted. The pressure roller 19 fixes the toner of the intermediate transfer body 15 melted by the heating device 18 on the print medium. Thus, the heating device 18 and the pressure roller 19
Without directly heating the print medium,
Since a configuration is adopted in which the toner attached to the sheet is melted and fixed on the print medium, print media other than paper can be handled.

FIGS. 4 and 5 are views for explaining the heating structure of the intermediate transfer member. After each of the four color toners has been transferred from the photoreceptor to the intermediate transfer member a total of four times, the toner transferred to the intermediate transfer member is heated, and then melted once on a print medium such as paper. Transcribed. When heating the intermediate roller, it is necessary to heat only the surface of the intermediate transfer body and the toner transferred thereon.

This intermediate transfer process can be subdivided into the following processes. The first process is a primary transfer process in which electrostatic transfer is performed for each color from a photoconductor to an intermediate transfer body. In this process, it is necessary to transfer 100% or almost 100% of the image on the photoconductor without destroying the image. Further, the image once transferred onto the intermediate transfer member must be prevented from returning to the photosensitive member.
When transferring the first color toner on the photoreceptor or transferring another color toner on the previously transferred toner, the transfer must be performed with the same transfer efficiency and image quality. .

The second process is a heating and melting process for heating and melting the toner. It is necessary to volatilize the volatile components and bring them into a molten state sufficient for transfer to a medium. Also,
When a contact means such as a heat roller or a heat belt is used, it is necessary that the toner does not transfer to the contact means and that the image quality does not deteriorate.

The third process is a secondary transfer process for performing a melt transfer to a medium. This must be able to transfer 100% of the molten toner to the medium.

In addition, there is a process for cooling and cleaning the intermediate transfer member after the melt transfer to the medium. In FIG. 4, as an external heat source of the intermediate transfer roller exemplified as the intermediate transfer member, a heat roller having a heat source therein is provided outside the intermediate transfer roller so as to be driven and rotated by the intermediate transfer roller. Due to the contact heat transfer between the heat roller and the intermediate transfer roller, the surface of the intermediate transfer roller and the toner transferred thereon are heated. A toner release coat layer such as a fluorine coating can be formed so that the toner does not adhere to the surface of the heat roller. Also, the surface layer of the heat roller and the intermediate transfer roller,
A metal material such as aluminum or copper having good thermal conductivity can be used. Thereby, the contact heat transfer from the heat roller to the intermediate transfer roller can be made better, and the surface temperature of the intermediate transfer roller can be made sufficiently high.

In FIG. 5, the surface of the intermediate transfer roller is
It is heated by a non-contact heating source by radiant heat transfer, for example, a halogen lamp. Further, a reflector (reflecting plate) for reflecting radiant heat from the halogen lamp toward the intermediate transfer roller is provided. With such a radiation heat transfer source, not only the surface of the intermediate transfer roller but also the toner is directly heated. At this time, a radiation heat transfer source that does not make a difference between the four colors of the toner is selected. It is desirable to do. As such a radiation heat transfer source, a far-infrared halogen heater can be used.

FIG. 6 shows an example of the structure of the intermediate transfer member heated by the above-mentioned external heat source. Here, the intermediate transfer roller exemplified as a roller configuration is provided with a rigid drum made of metal such as aluminum at the center. This drum has conductivity so that a voltage can be applied from a shaft or the like in order to transfer a toner image of a photoreceptor onto an intermediate transfer member by electrostatic force.
It has a hardness for applying a pressure necessary to melt-transfer the transferred toner onto a medium such as paper. On this drum, a conductive and heat-resistant elastic layer and a surface layer having conductivity, heat resistance, peelability and preferably silicone oil resistance are provided. The surface roughness of the surface layer is desirably about the average particle diameter of the toner (1 μm) or less.

When heating the toner on the intermediate transfer member,
As a result, the intermediate transfer body itself is heated. Further, the heated toner needs to be kept in a molten state from the time the toner is separated from the heat belt to the time the paper contacts the printing medium under pressure. By forming the intermediate transfer member into a layer structure, the heat retention can be improved. For this reason, when the intermediate transfer member is composed of at least two layers of the elastic layer and the surface layer, the heat transfer properties of the intermediate transfer member and the surface heat retention characteristics can be improved.

As the elastic layer, a low-elastic solid (non-porous) rubber, for example, a conductive silicone rubber having an Asker C hardness of about 60 degrees can be used. Alternatively, as the elastic layer, a conductive porous body, for example, Asuka C hardness 3
A conductive foamed silicone rubber of about 0 degrees can be used. It is desirable that the foaming be separated into independent foams to form independent foams.

A thin surface layer that receives heat is provided on the elastic layer. The amount of toner on the intermediate transfer member varies depending on a place or a printed image, particularly during full-color printing.
The heat capacity of the surface layer of the intermediate transfer member is made sufficiently larger than that of the toner layer so that the change in toner layer thickness does not affect the toner heating temperature. This can be achieved, for example, by selecting the thickness of the surface layer of the intermediate transfer member for a toner layer of 5 to 6 μm in total for four colors. As this surface layer, a conductive fluorine-based resin, for example, conductive PFA or PTFE (surface resistance of 10 ⁴ Ωcm, 30 μm) having conductivity, heat resistance, peeling property, and silicone oil resistance.
m) can be used. Further, as the surface layer, a fluorosilicone rubber, for example, conductive (10 ¹¹ Ωcm),
Shin-Etsu Chemical FE61 having heat resistance, peelability and silicone oil resistance can be used.

In particular, when the above-mentioned solid rubber is used as the elastic layer, the fluororesin or fluorosilicone rubber of the surface layer is sprayed directly onto the drum on which the elastic layer is formed by spraying the liquefied fluororesin directly on the elastic layer. Can be coated on top. This facilitates manufacturing.

When the above-mentioned porous body is used as the elastic layer, it is difficult to spray the surface layer directly because the surface is porous.
It can be wound on a porous elastic layer as a film having a thickness of about 0 to 50 μm.

With such a configuration, the heat capacity can be reduced as a whole and the amount of heat supplied can be reduced, while the surface temperature can be easily increased. In addition, since the heat capacity is small, the cooling performance after transferring the molten toner to a medium such as paper is good, and unnecessary heating of the photoconductor is eliminated. The thickness of the surface layer is as thin as the strength permits, and preferably 30 to 100 μm, whereby the instantaneous heating property and power saving are further improved.

Alternatively, as shown in FIG. 7, a heat-resistant and conductive film having a thickness of about 10 to 50 μm, a conductive polyimide (for example, DuPont conductive Kapton,
40 μm) to a fluorosilicone rubber (for example, Shin-Etsu Chemical F
E61, 30 μm). By making the elastic layer a conductive silicone sponge (10 ^3-4 Ωcm) of about 1.5 mm and the surface layer of about 70 μm, the intermediate transfer member can be brought into contact with the photosensitive member in the primary transfer. The amount becomes about 0.1 mm,
It functions as an elastic body due to the elasticity of the sponge and the elasticity of the fluorosilicone rubber. On the other hand, in contact with the heat belt or the backup roller, the sponge portion is sufficiently crushed and the rigidity of the aluminum roller appears, so that sufficient pressure is applied. Moreover, the expansion and contraction of the surface layer is relatively small due to the polyimide layer, so that the expansion and contraction of the image is reduced and the deterioration of the image quality is reduced.

In order to stably and reduce the pressure applied to the photoreceptor, it is desirable to increase the radius of curvature of the photoreceptor and the intermediate transfer member to increase the contact area between them, that is, the nip width. In addition, as shown in FIG. 8, contact flanges are provided coaxially on both sides of the intermediate transfer member, so that the amount of displacement of the intermediate transfer member can be regulated to a constant value. The contact flange is provided to maintain a constant distance between the intermediate transfer member and the photosensitive member, and must be basically insulative. This can be made of, for example, an insulating resin, or can be made by providing an insulating resin layer on a metal surface to improve accuracy. Thus, the intermediate transfer member can be brought into contact with the photoreceptor, and the nip pressure between the two can be maintained optimally.

FIGS. 9 and 10 are views for explaining a heating method in which a heat roller is brought into contact with an intermediate transfer belt and heated only during fusion transfer. FIG. 9 shows when the heat belt is retracted, and FIG. 10 shows when the heat belt is in contact.

After the toner of the photoreceptor has been transferred to the intermediate transfer belt in four colors, it must be melt-transferred to a print medium such as paper at one time. This can be achieved by bringing the belt driven by the heat roller into contact with the intermediate transfer roller only at the time of melt transfer by the contact / retreat mechanism.

The heater provided inside the heat roller, such as a halogen lamp, is turned on in advance so that the heat roller reaches an appropriate temperature during the fusion transfer, and is heated. The contact / retreat mechanism heats the contact only when necessary, so that unnecessary heat is not applied to the photoreceptor, and the toner is not melted before the fusion transfer.
Further, a stable temperature can be obtained from the leading end of the medium without worrying about the rise time of the temperature rise of the belt. At this time, the toner temperature is set to the set temperature (100
２００200 ° C.), the heat capacity of the heat belt is made larger than the heat capacity of the surface resin layer of the intermediate transfer member.

FIGS. 11 to 13 are diagrams illustrating an intermediate transfer member heating method according to the present invention. In these examples,
The heat belt is driven between two rollers,
At least one of the rollers is constituted by a heat roller using a halogen lamp or the like as a heat source. Preferably, both rollers are configured as a heat roller, and the contact time between the belt and the heat roller is increased in order to recover the temperature of the heat belt that drops during heating of the toner and the intermediate transfer body,
It is advantageous to encourage belt temperature recovery. Since the heating is performed by the belt having a constant length, the contact can be soft and the heating can be performed for a long time. In this way,
The toner image to be heated is heated and melted by contact heat transfer from the surface.

Since the heat belt is heated while being in contact with the toner on the intermediate transfer member, the heat belt must be releasable so that the molten toner does not adhere to the heat belt. In other words, the wettability to the molten toner requires that the surface of the intermediate transfer member be larger than the surface of the heat belt, and that the surface of the print medium be larger than that. As a result, all the toner heated by the heat belt does not adhere to the heat belt, but remains on the intermediate transfer member, and then is entirely melt-transferred onto the print medium.

In order to better heat and melt the toner image on the intermediate transfer member, it is necessary to increase the heat energy transferred from the heat belt to the toner image and the surface portion of the intermediate transfer member. However, the heat capacity (thickness) of the heat belt that stores heat energy has an upper limit due to the repetitive compression / tensile stress fatigue limit generated in the belt by the roller winding drive. For this reason, it is desirable that the heat belt be made of a metal having good thermal conductivity as a whole or the base material, thereby promptly supplying heat from the heat belt to the intermediate transfer member and recovering the temperature of the heat belt. For example, a nickel belt of several tens μm level can be practically used.

Since the heat belt and the toner image on the intermediate transfer member are in contact with each other, the state of mutual contact affects the image quality. Therefore, when the heat belt is desirably brought into contact, the heat belt is softly contacted only at the so-called antinode portion located between the rollers, excluding the roller contact portion. Such a configuration can be achieved by increasing the distance between the rollers. Further, in order to supply thermal energy to the toner on the intermediate transfer member, it is desirable that the heat belt and the intermediate transfer member are brought into contact at the same speed.

In the examples shown in FIGS. 11 to 13, an internal heat source is provided on the back side of the abdomen of the belt in order to replenish heat energy to the heat belt whose temperature drops due to heat transfer by contact with the toner.

As shown in FIG. 12, in order to increase and stabilize the reheating efficiency of the heat belt whose temperature has dropped,
The internal heat source can be a fixed heater block having a sufficient heat capacity with respect to the heat belt, and can be brought into sliding contact with the back side of the heat belt abdomen. In this case, the material of the heater block is desirably a metal having a high thermal conductivity such as copper or aluminum. For example, the heater block may be formed by embedding a sheathed heater in an aluminum block. In addition, it is necessary to secure a contact width with the back side of the heat belt abdomen. Therefore, the portion of the fixed heater block that contacts the heat belt is formed into a concave curved surface having an intermediate transfer roller diameter or a slightly larger curvature. It is desirable.

In the heat transfer of the internal heater to the back side of the heat belt, the sliding contact heating by the fixed heater block has a simple structure, but the chattering vibration (stick slip) due to dynamic friction and the stability and life of the mechanism due to sliding wear. Has difficulties. For this reason, FIG. 11 shows an example in which the internal heat source is a heat roller that rotates in contact with and rotates behind the belt.

As shown in FIG. 13, a radiant heat source such as a halogen lamp is provided as an internal heat source, and heat energy can be supplied to the heat belt in a non-contact manner. At this time, it is desirable to install a reflector around the halogen lamp to concentrate infrared rays on the back side of the abdomen of the belt in contact with the intermediate transfer member. If the back side of the heat belt is made of a metallic glossy surface such as Ni and has the property of easily reflecting infrared rays, the absorption of infrared energy into the belt can be enhanced by blackening the back side of the belt with heat-resistant paint or the like. it can.

At the end of heating the heat belt, the toner particles melt to achieve 100% fusion transfer efficiency.
The laminated toner images need to be integrated. In particular, in the case of a liquid developing system using a non-volatile carrier oil, it is effective to apply pressure to the aggregation and coalescence of the molten toner particles. This integration of the toner image is effective for the releasability from the heat belt (without offset).
It is valid.

In order to promote the fusion and integration of the toner on the intermediate transfer member during the contact with the heat belt, it is necessary to positively apply a belt tension roller to the intermediate transfer member. The pressing force does not hinder the input of the toner layer to the contact portion between the heat belt and the intermediate transfer body, and the belt tension roller on the primary transfer side does not crush the image in order to prevent the crushing of the fused toner image. Can be soft or non-contact. Further, it is desirable to increase the tension roller on the fusion transfer side at the final portion of the heat belt contact where the toner on the intermediate transfer member is sufficiently heated.
In this case, the tension roller integrates the toner image sufficiently heated and melted at the belt contact portion with a pressure that does not crush the toner image, and forms a fused toner layer without offset on the belt surface. Further, it is desirable that the internal heat roller is also positively pressed toward the intermediate transfer member.

As described above, the belt contact / retreat mechanism drives the respective rollers, belts, etc. as a whole with respect to the intermediate transfer member, so that the belt contacts / retracts.
Retraction is performed, but in addition, each tension roller can be individually pressed by an independent pressing structure. The heat roller as the internal heat source and the fixed heater block can also be independently pressed. Further, it is desirable that the belt surface on the side in contact with the intermediate transfer member be a tension side, and this can be achieved by driving the belt from a belt tension roller on the fusion transfer side. As a result, the contact of the belt at the time of contact with the intermediate transfer member can be made sufficient, and the contact thermal resistance can be reduced.

[0055]

According to the present invention, when a high-viscosity, high-concentration developer composed by dispersing a high-concentration toner in silicone oil or the like is used, the heat capacity of the toner is small due to the small toner particles. Utilizing certain characteristics, at a position before contacting the pressure roller, the surface of the intermediate transfer body is configured to be partially heated, and the intermediate transfer body is made of a metal drum,
By forming a conductive and heat-resistant elastic layer on the surface of the metal drum and a surface layer having conductivity, heat resistance, peelability and silicone oil resistance, the photoconductor is not affected by heat. In addition, the toner transferred to the intermediate transfer member can be efficiently heated and melted. Furthermore, as the heating means, the heat belt is brought into contact with the intermediate transfer body at the same speed, and an internal heat source is provided on the back side of the abdomen of the belt, so that the optimal heat energy is applied to the heat belt, which lowers its temperature due to heat transfer by contact with toner. Can be replenished stably.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a wet electrophotographic apparatus according to the present invention.

FIG. 2 is an explanatory diagram of functions of an applicator roller and a developing roller.

FIG. 3 is an explanatory diagram of a function of a pre-wet layer applied by a pre-wet process.

FIG. 4 illustrates an example of heating of the intermediate transfer member using a heat roller.

FIG. 5 illustrates an example of heating of the intermediate transfer member using a halogen heater.

FIG. 6 shows an example of the configuration of an intermediate transfer member according to the present invention.

FIG. 7 shows another example of the structure of the intermediate transfer member according to the present invention.

FIG. 8 is a diagram exemplifying a means for regulating a displacement amount of an intermediate transfer member with respect to a photoconductor at a constant value.

FIG. 9 is a view for explaining a configuration in which the heat belt is brought into contact with the intermediate transfer roller only at the time of fusion transfer, and shows a state where the heat belt is retracted.

FIG. 10 is a view for explaining a configuration in which the heat belt is brought into contact with the intermediate transfer roller only at the time of melt transfer, and shows a state at the time of heat belt contact.

FIG. 11 shows a heating method using a heat belt according to the present invention, and shows an example in which a heat roller is provided therein.

FIG. 12 shows a heating method using a heat belt according to the present invention, and shows an example in which a fixed heater block is provided therein.

FIG. 13 shows a heating method using a heat belt according to the present invention, and shows an example in which a halogen lamp and a reflector are provided therein.

FIG. 14 shows a conventional intermediate transfer body in which a halogen heater is disposed in a hollow portion of a hollow metal drum to heat the entire intermediate transfer body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Photoconductor (drum) 11 Charging device 12 Exposure device 13 Prewet device 14 Developing device 15 Intermediate transfer member (roller) 16 Blade 17 Static elimination device 18 Heating device 19 Pressure roller

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Satoru Honoka 98 Uno-nu, Unoki-cho, Hebei-gun, Ishikawa Prefecture 2 Within PFU Inc. (72) Inventor Motoharu Ichida Unoki-nu, Unoki-cho, Kawakita-gun, Ishikawa 98-2 Inside PFU Co., Ltd. (72) Inventor Masahisa Takahata Unoki-cho, Unoki-cho, Kawakita-gun, Ishikawa Prefecture 98-2 Inside PFU Co., Ltd. (72) Inventor Shigeharu Okano, Unoki-nu, Unoki-cho, Kawakita-gun, Ishikawa 98-2 Inside PFU Co., Ltd. (72) Inventor Yasukazu Takeda 98-2 Unoki Nu, Unoki-cho, Kawakita-gun, Ishikawa Prefecture

Claims (18)

[Claims] 1. A wet electrophotographic apparatus using a non-volatile, high-viscosity, high-concentration liquid toner as a liquid developer, comprising: an image support on which an electrostatic latent image is formed; and a surface of the image support. A pre-wet liquid applying means for applying a film of a pre-wet liquid, and a liquid toner as a liquid developer is supplied to the image support in contact with the image support, and between the image support and Developing means for adhering toner particles to exposed or unexposed parts of the image support in accordance with the generated electric field; a metal drum; a conductive and heat-resistant elastic layer on the surface of the metal drum; An intermediate transfer member comprising a surface layer having heat resistance, heat resistance, and releasability, and transferring toner particles adhering to the image support in accordance with an electric field generated between the image support and the image transfer member; Abuts on the intermediate transfer member A pressure roller that rotates and conveys a print medium while pressing the intermediate transfer member, and a heating unit that partially heats the surface of the intermediate transfer member at a position before contacting the pressure roller. A wet electrophotographic apparatus, comprising: 2. The wet electrophotographic apparatus according to claim 1, wherein said elastic layer is made of low elastic solid rubber. 3. The wet electrophotographic apparatus according to claim 1, wherein said elastic layer is made of a conductive porous body. 4. The wet electrophotographic apparatus according to claim 1, wherein the surface layer is made of a conductive fluorine-based resin or fluorosilicone rubber. . 5. The wet electrophotographic apparatus according to claim 4, wherein the conductive fluorine-based resin or fluorosilicone rubber is liquefied and coated on the elastic layer by spraying. A wet electrophotographic apparatus. 6. The wet electrophotographic apparatus according to claim 4, wherein the conductive fluorine-based resin or fluorosilicone rubber is formed into a film and wound on an elastic layer. Wet electrophotographic equipment. 7. The wet electrophotographic apparatus according to claim 1, wherein the elastic layer is made of a conductive silicone sponge, and the surface layer is made of a conductive polyimide film coated with a fluorosilicone rubber. A wet electrophotographic apparatus. 8. The wet electrophotographic apparatus according to claim 1, wherein attached flanges for regulating an amount of displacement of the intermediate transfer member with respect to the photosensitive member are provided on both sides of the intermediate transfer member. A wet electrophotographic apparatus. 9. The wet electrophotographic apparatus according to claim 1, wherein at least one heating means for heating the surface of the intermediate transfer member is a heat belt driven by a plurality of heat rollers using a halogen lamp as a heat source. A wet electrophotographic apparatus characterized by heating by contact with the abdomen. 10. The wet electrophotographic apparatus according to claim 9, wherein said heating means contacts the heat belt with the intermediate transfer body at the same speed, and further comprises an internal heat source on the back side of the abdomen of the belt. A wet electrophotographic apparatus characterized in that heat energy is supplied to a heat belt whose temperature drops due to contact heat transfer to a heat belt. 11. The wet electrophotographic apparatus according to claim 10, wherein said internal heat source comprises a fixed heater block which is in sliding contact with the back side of the heat belt abdomen. 12. The wet electrophotographic apparatus according to claim 11, wherein the fixed heater block has a concave curved surface shape in which a portion in contact with a heat belt has a curvature equal to or slightly larger than the diameter of the intermediate transfer member. A wet electrophotographic apparatus, characterized in that: 13. The wet electrophotographic apparatus according to claim 10, wherein said internal heat source is constituted by a heat roller which rotates in contact with and rotates behind a heat belt abdomen. 14. The wet electrophotographic apparatus according to claim 10, wherein the internal heat source comprises a radiant heat source such as a halogen lamp for supplying heat energy to the heat belt in a non-contact manner. . 15. The wet electrophotographic apparatus according to claim 14, wherein the radiant heat source is provided with a reflector for concentrating radiant heat, and blackens the back surface of the heat belt with a heat-resistant paint to absorb energy. A wet electrophotographic apparatus characterized by enhancing. 16. The wet electrophotographic apparatus according to claim 9, wherein said belt tension roller is pressed against an intermediate transfer member, and said pressure is applied to a belt tension roller on a primary transfer side. A wet electrophotographic apparatus, characterized in that the pressure is soft enough not to crush the image, and that the tension roller on the melt transfer side at the last part of the heat belt contact is pressed higher. 17. The wet electrophotographic apparatus according to claim 16, wherein the belt contact / retreat mechanism is configured such that each tension roller is independently pressed against the intermediate transfer body by an independent pressing structure. Characteristic wet electrophotographic apparatus. 18. The wet electrophotographic apparatus according to claim 9, wherein the heat belt is driven by a belt tension roller on a fusion transfer side to contact the intermediate transfer body. A wet electrophotographic apparatus characterized in that the surface is a tight side.