JPH07239615A - Liquid electrostatic latent image developing method and liquid developing apparatus - Google Patents

Abstract

(57) [Summary] [Object] To provide a liquid developing method and a liquid developing apparatus for an electrostatic latent image, which can prevent toner from adhering to a non-image portion on an image support and disturbing the image. A liquid developing method of an electrostatic latent image, which develops an electrostatic latent image formed on a photoconductor 10 with toner, comprising: a pre-wetting step of applying a prewetting liquid on the photoconductor 10; A thin layer of a high-viscosity liquid developer in which toner is dispersed at a high concentration in an insulating liquid is formed on the developing roller 506, and the liquid developer layer on the developing roller 506 and the photosensitive layer are exposed while rotating the developing roller 506. And a developing step of supplying a liquid developer to the latent image surface on the photoconductor 10 by bringing it into contact with the pre-wet liquid layer on the body 10.

Description

Detailed Description of the Invention

[0001]

The present invention relates to electrophotography, electrostatic recording,
The present invention relates to a liquid developing method and a liquid developing apparatus for an electrostatic latent image, which visualizes an electrostatic latent image formed by a method such as ionography using a liquid developer.

[0002]

2. Description of the Related Art Conventionally, in an electrostatic latent image liquid developing apparatus for developing an electrostatic latent image formed on an image support with toner, which is a charged image-forming particle, a latent image surface of the image support is used. As a method of supplying the liquid developer to the surface of the developing roller, which is a developer support, the surface of the developing roller is provided with unevenness, and the liquid developer is held in the recess and supplied to the image support. By using this sponge roller against the image support, the liquid developer absorbed by the sponge roller is supplied to the image support, or the image support is placed in a developer tank in which the liquid developer is stored. A method is used in which the liquid developer is directly supplied to the image support by dipping without using the developer support.

[0003]

By the way, in a conventional electrostatic recording apparatus or the like, a low-viscosity toner obtained by mixing a toner with IsoparG (registered trademark: manufactured by Exxon) at a ratio of about 1 to 2% is generally used. Liquid developer is used. However, in order to suppress the vapor generation of the solvent and realize a safer and more compact liquid developing device, it is preferable to use a liquid developer having a higher concentration than the liquid developer used in the conventional device. No such device has hitherto been found. Therefore, a high-concentration and high-viscosity liquid developer (a high-viscosity liquid developer of 100 to 10000 mPa · s in which toner is dispersed in an insulating liquid at a high concentration) in which adhesion to the image support is increased.
In the case of using, it is not clear what method is suitable as a method for supplying the liquid developer to the latent image surface of the image support.

[0004]

The present invention has been made in view of the above circumstances, and uses a high-concentration high-viscosity liquid developer capable of preventing toner from adhering to a non-image portion on an image support and disturbing an image. Another object of the present invention is to provide a liquid developing method and a liquid developing apparatus for an electrostatic latent image.

[0005]

In order to achieve the above-mentioned object, a liquid developing method for an electrostatic latent image according to the present invention is a method for developing an electrostatic latent image formed on an image support with charged developing particles. A liquid developing method for an electrostatic latent image, which is developed with a certain toner,
A thin layer of highly viscous liquid developer in which toner is dispersed in insulating liquid at a high concentration is formed on a cylindrical developer support having elasticity, and this developer support is driven by the image support. And a developing step of supplying the liquid developer to the latent image surface of the image support by bringing the liquid developer layer on the developer support into contact with the image support while rotating in a rotating direction. It is a thing. The viscosity of the liquid developer is 100-
It is desirable that the liquid developer layer on the developer support has a layer thickness of 5 to 40 μm. The hardness of the developer support is preferably 5 to 60 degrees JIS-A.

A roller having an outer diameter slightly smaller than the outer diameter of the developer support is provided on both sides of the developer support, and the roller is brought into contact with the image support to press the developer support against the image support. It is desirable to adjust the force.

Further, it is desirable that at least the surface of the developer support is formed of a conductive member that does not absorb the liquid developer.

Further, the developer support may have a foam inside.

Further, in the liquid developing method for an electrostatic latent image of the present invention, prior to the developing step, a pre-wetting liquid, which is a dielectric liquid having releasability and chemically inert, is formed on the image support. It is desirable to have a pre-wetting step of applying.

[0010]

According to the liquid latent electrostatic image developing method of the present invention, an elastic cylindrical developer support is rotated in the direction in which the image support is driven, and an image is formed on the liquid developer layer on the developer support. By bringing the developer support into contact with the support, the developer support is elastically deformed in the developing region. Therefore, it is possible to disperse the contact pressure when the liquid developer layer on the developer support and the image support are brought into contact with each other. it can. For this reason, it is possible to prevent the liquid developer layer on the developer support from being excessively crushed in the developing area, thereby preventing the toner from adhering to the non-image portion on the image support and disturbing the image. Further, by developing the liquid developer in which the toner is dispersed at a high concentration in a thin layer and developing the liquid developer, the liquid amount can be made much smaller than that of the conventional low concentration liquid developer. The liquid developer has a viscosity of 1
When it is 0000 mPa · s or more, it becomes difficult to stir the insulating liquid and the toner, and there is a problem in how to make the liquid developer. Therefore, 10,000 mPa · s
The liquid developer described above becomes unrealistic in terms of cost and becomes unrealistic. On the other hand, when it is 100 mPa · s or less, the toner concentration becomes low and the dispersibility of the toner becomes poor, so that it becomes impossible to develop the developer in a thin layer.
The layer thickness of the liquid developer is thin when the toner concentration is high,
It needs to be thick when it is low. In addition, the higher the viscosity, the thinner it needs to be. However, when the layer thickness is thicker than 40 μm, excessive adhesion of toner occurs and image noise occurs. On the other hand, when the layer thickness is thinner than 5 μm, unevenness occurs when the image of the solid portion is output. If the hardness of the developer support is 5 degrees JIS-A or less, it is too soft and it becomes difficult to maintain a constant shape. On the other hand, when the hardness is 60 degrees JIS-A or more, it is too hard, so that the liquid developer layer on the developer support can be brought into contact with the image support without excessively crushing the liquid developer layer. The developer support must be installed so as to form a minute gap or gap between the developer support and the image support. Therefore, it is difficult to install the developer support.

A roller having an outer diameter slightly smaller than the outer diameter of the developer support is provided on both sides of the developer support, and the rollers are brought into contact with the image support so that the developer support is pressed against the image support. When the force is adjusted, the contact pressure when the liquid developer layer on the developer support and the image support are brought into contact with each other can be easily adjusted.

When at least the surface of the developer support is formed of a conductive member that does not absorb the liquid developer,
When the liquid developer layer on the developer support and the image support are in contact with each other and the developer support is elastically deformed, the developer support absorbs or releases the liquid developer to form a liquid. It is possible to prevent the developer layer from being disturbed.

Further, when a developer support having a foam inside is used, a developer support having a desired hardness can be obtained relatively easily.

If a pre-wetting step of applying a pre-wetting liquid, which is a dielectric liquid having releasability and chemically inert, is provided prior to the developing step, the present invention supports the developer. Since the elastic body is used, the liquid developer layer on the developer support and the pre-wet liquid layer on the image support can be brought into contact with each other in the developing area while maintaining the two-layer state. Therefore, since the liquid developer layer contacts the surface of the image support through the pre-wet liquid layer,
It is possible to more effectively prevent the image from being disturbed by the toner adhering to the non-image portion on the image support.

The viscosity of the pre-wet liquid is 0.5 to 5 m.
Pa · s, electric resistance of 10 ¹² Ωcm or more, boiling point of 100
When the surface tension is ˜250 ° C. and the surface tension is 21 dyn / cm or less, a pre-wetting liquid having releasability and good insulation can be obtained. The pre-wetting liquid is absorbed by paper or the like at the time of transfer, and thus needs to be evaporated at the time of fixing. Therefore, the viscosity is 0.5 in order to easily evaporate.
~ 5 mPa · s is desirable. If the viscosity is 5 mPa · s or more, it becomes difficult to evaporate, and if the viscosity is 0.5 mPa · s or less, the volatility becomes high, and therefore it is regarded as a hazardous material and is not suitable.
If the boiling point is 100 ° C. or lower, the amount of evaporation increases, which causes a problem in the method of storing the pre-wet liquid, the entire device must be hermetically sealed, and it is difficult to improve the working environment. On the other hand, when the boiling point is 250 ° C. or higher, the paper is curled at the time of fixing and cannot be used, and high energy for heating is required, resulting in high cost.
When the electric resistance is 10 ¹² Ωcm or less, the insulating property is deteriorated and the prewetting liquid cannot be used. Therefore, it is desirable that the electric resistance value is as high as possible. When the surface tension is 21 dyn / cm or more, the wettability becomes poor and the compatibility with the liquid developer becomes poor. Therefore, it is desirable that the surface tension be as low as possible.

In the liquid developing method for electrostatic latent images of the present invention, the insulating liquid has a viscosity of 0.5 to 1000 mPa · s, an electric resistance of 10 ¹² Ωcm or more, a surface tension of 21 dyn / cm or less, and a boiling point of 100 ° C. When the liquid developer described above is used, a high-viscosity liquid developer can be obtained. Since the liquid developer layer formed on the developer support is formed in a thin layer, the insulating liquid contained in the liquid developer layer is extremely small, so that it is supplied to the latent image surface of the image support. The insulating liquid contained in the liquid developer is extremely small. Therefore, the amount of insulating liquid absorbed by paper or the like during transfer is extremely small, and the viscosity is 1000 mPa · s.
If the following is satisfied, the problem of the insulating liquid adhering to paper or the like does not occur. However, if the viscosity is 0.5 mPa · s or less, the volatility becomes high and it is not suitable as a hazardous material.
When the boiling point of the insulating liquid is 100 ° C. or less, the amount of evaporation is large, so that there is a problem in the method of storing the developer, the entire device must have a closed structure, and it is difficult to improve the working environment. . When the electric resistance is 10 ¹² Ωcm or less, the insulating property is deteriorated, and the toner has a problem of conductivity and cannot be used as a developer. Therefore, it is desirable that the electric resistance be as high as possible. Surface tension is 21 dyn
If it is above / cm, the wettability will be poor and the compatibility with the pre-wetting liquid will be poor. Therefore, it is desirable that the surface tension be as low as possible.

When the liquid developer contains a toner having an average particle diameter of 0.1 to 5 μm in a concentration of 5 to 40%, a liquid developer in which the toner is dispersed in an insulating liquid at a high concentration is obtained. You can In addition, the resolution is improved in almost inverse proportion to the particle size of the toner. Usually, the toner becomes a mass of about 5 to 10 on the printed paper,
Since they exist, the resolution becomes poor when the average particle diameter of the toner is 5 μm or more. On the other hand, when the average particle diameter of the toner is 0.1 μm or less, the physical adhesive strength increases, and it becomes difficult to remove the toner during transfer.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. 1 is a schematic configuration diagram of an electrostatic latent image liquid developing device according to a first embodiment of the present invention, and FIG. 2 is a schematic perspective view of a pre-wetting device used in the electrostatic latent image liquid developing device shown in FIG. 3, FIG. 3 is a diagram for explaining the operation of the electrostatic latent image liquid developing device shown in FIG. 1, FIG. 4 is a diagram for explaining the operation of the pre-wetting device shown in FIG. 2, and FIG. 5 is a pre-wetting liquid. FIG. 15 is a diagram showing the flow of the pre-wet liquid when the supply member is brought into contact with the photoconductor, FIG. 15 is a schematic diagram of the developing device used in the liquid developing device for the electrostatic latent image shown in FIG. 1, and FIG. FIG. 17 is a schematic view of a developing roller used in the developing device shown in FIG. 17, and FIG. 17 is a diagram for explaining a contact method between the photoconductor and the developing roller.

As shown in FIG. 1, the electrostatic latent image liquid developing apparatus according to the first embodiment of the present invention applies a photoreceptor 10 as an image support and a pre-wet liquid onto the photoreceptor 10. A pre-wetting device 20, a charging device 30 that charges the photoconductor 10, an exposure device 40 that exposes an image on the photoconductor 10,
A developing device 50 that visualizes the electrostatic latent image by supplying toner to the portion of the photoconductor 10 on which the electrostatic latent image is formed;
Transfer device 6 for transferring toner on photoconductor 10 to a predetermined paper
0 and a cleaning device 70 that removes the toner adhering to the photoconductor 10.

Charging device 30, exposure device 40, transfer device 6
For the cleaning device 70, the conventional technique used in the conventional electrophotographic printer can be used in most cases. Therefore, in this embodiment, the description of each of the above-described devices will be omitted, and the pre-wetting device 20 and the developing device 50, which are the main parts of the present invention, will be described.

The pre-wetting device 20 of this embodiment is shown in FIG.
As shown in, a plate-shaped pre-wet liquid supply body 202 having a length substantially the same as the image width drawn on the photoconductor 10, a case 204 for housing the pre-wet liquid supply body 202,
A tank 206 for storing the pre-wet liquid 220, a pump 208 for pumping the pre-wet liquid 220 stored in the tank 206, tubes 210a and 210b, and a displacement device 212 are provided.

As the pre-wet liquid supply body 202, a continuous porous body having a three-dimensional network structure in which pores are continuous, for example, Belleater (registered trademark: Kanebo Co., Ltd.) is used.
The bell eater is pre-wet liquid 220 for the volume of the pores.
When the pre-wet liquid 220 exceeding the pore volume is supplied, the pre-wet liquid 220 can be uniformly discharged in the direction perpendicular to the flow direction of the pre-wet liquid 220. Case 20
As shown in FIG. 4, on the surface of No. 4 facing the photoconductor 10,
An opening 204a is provided so that the bottom surface of the pre-wet liquid supply body 202 can be brought into contact with the photoconductor 10. The tube 210 a uses the pre-wet liquid 220 pumped by the pump 208 to supply the pre-wet liquid supply body 2
02 to the supply side 202a. A space portion 204b is formed between the supply side 202a of the pre-wet liquid supply body 202 and the case 204.
20 is stored in this space portion 204b, and then the supply side 20
It is supplied from 2a. The tube 210b conveys the pre-wet liquid 220 discharged from the discharge side 202b of the pre-wet liquid supply body 202 to the tank 206. When a signal is not input from the outside, the displacement device 212 holds the pre-wet liquid supply body 202 at a position apart from the photoconductor 10 as shown in FIG. 4A, and the signal is input from the outside. In the meantime, as shown in FIG. 4B, the pre-wet liquid supply body 202 is brought into contact with the photoconductor 10.

As shown in FIG. 15, the developing device 50 of this embodiment stores a bellows pump 502 for storing and discharging a high-concentration and high-viscosity liquid developer 508, which will be described later, and a liquid developing device discharged by the bellows pump 502. A liquid reservoir 504 that stores the agent 508, a developing roller 506 that is a developer support provided so that the lower portion is immersed in the liquid developer 508 stored in the liquid reservoir 504, and the layer thickness of the liquid developer 508 is adjusted. Regulating roller 510 formed of elastic member
And a scraping blade 512 for scraping off the liquid developer 508 attached to the developing roller 506.

The developing roller 506 has a length substantially the same as the width of the image drawn on the photosensitive member 10, and as shown in FIG. 16, a cored bar 50 formed of a rigid body such as stainless steel.
6a, a cylindrical body 506b having elasticity formed around the core metal 506a, and a surface layer 506c formed on the surface of the cylindrical body 506b. As the elastic member forming the columnar body 506b, there is a foamed material such as polystyrene, polyethylene, polyurethane, polyvinyl chloride, NBR (nitrile butylene rubber), or a low hardness rubber member such as silicon rubber or urethane rubber. . However, in general, when a rubber member is used for many years in a state of being elastically deformed, it may be permanently deformed and may not return to its original shape, that is, a cylindrical shape. Therefore, it is preferable to use a foamed material for the elastic member forming the columnar body 506b if possible. The surface layer 506c is formed of a conductive member that does not swell in silicon oil that is a carrier liquid of the liquid developer 508 described later. The electric resistance value of the conductive member is preferably about 10 ³ Ωcm so that an electric developing bias can be applied to the developing roller 506. As a method of forming the surface layer 506c on the surface of the columnar body 506b, for example, a method of coating the surface of the columnar body 506b with a synthetic rubber-based binder in which conductive particles such as carbon black are dispersed, or the columnar body 506b is made conductive. There is a method of covering with a heat-shrinkable tube having properties and applying heat to this to shrink the heat. Alternatively, the columnar body 506b may be formed inside the surface layer 506c by injecting an elastic material into the tube having conductivity or foaming the injected elastic material. As the tube having conductivity, a resin tube made of polyimide, polycarbonate, nylon or the like or a metal tube made of nickel or the like is used. Further, as the heat-shrinkable tube having conductivity, P
A resin tube such as FA or PTFE is used. These tubes are preferably so-called endless tubes without joints. When the columnar body 506b is formed of an elastic member that does not swell in silicon oil such as urethane rubber, the surface layer 506c is formed on the surface of the columnar body 506b.
Need not be formed. However, in order to apply an electric developing bias to the developing roller 506, the surface of the cylindrical body 506b is subjected to conductive processing, or conductive fine particles are added to an elastic member forming the cylindrical body 506b.
It is necessary to set the electric resistance value to a desired value, that is, about 10 ³ Ωcm.

As shown in FIG. 15, the developing roller 506 is arranged so as to contact the photoconductor 10,
In the direction opposite to the rotation direction of the photoconductor 10, that is, the photoconductor 1
Rotate in the direction of 0. As a result, the liquid reservoir 50
4, the liquid developer 508 stored in
0 surface. As shown in FIG. 15, the developing roller 506 has a nip width t formed in the developing area by elastic deformation caused by the pressing force of the developing roller 506 against the photoconductor 10. The hardness of the developing roller 506 is preferably 5 to 60 degrees JIS-A. When the hardness is 5 degrees JIS-A or less, it is difficult to maintain a constant shape because it is too soft. On the other hand, the hardness is 60 degrees JI
If it is S-A or higher, the developing roller 506 is too hard.
To bring the upper liquid developer layer and the pre-wet liquid layer on the photoreceptor 10 into contact with each other while maintaining the two-layer state, the developing roller 5
It is necessary to install the developing roller 506 so as to form a minute gap, that is, a gap between the photosensitive drum 10 and the photoconductor 10. Therefore, it is difficult to install the developing roller 506. The nip width t generated by the elastic deformation of the developing roller 506 is set in relation to the developing time constant defined by the electric circuit including the capacity and resistance component formed by the developing roller, the developer layer and the photoconductor. .
The adjustment of the pressing force of the developing roller 506 against the photoconductor 10 is performed by the developing roller 5 as shown in FIGS. 17 (A) and 17 (B).
Contact rollers 507 that contact the photoconductor 10 on both sides of 06
Was arranged, and the abutting roller 507 was replaced with one having a different outer diameter.

The regulating roller 510 is arranged so as to contact the developing roller 506, and rotates in the direction opposite to the rotating direction of the developing roller 506. As a result, the layer thickness of the liquid developer 508 on the developing roller 506 is regulated to form a thin liquid developer layer on the developing roller 506. In an experiment conducted by the present inventors, the peripheral speed of the regulation roller 510 is set to the developing roller 5.
Good results were obtained at speeds approximately twice the peripheral speed of 06.

Next, the image forming material used in this embodiment will be described. Liquid developer 508 used in this embodiment
Is composed of a resin that serves as a binder such as epoxy, a charge control agent that imparts a predetermined charge to the toner, a color pigment, a toner that includes a dispersant that uniformly disperses the toner, and a carrier liquid. The toner composition is basically similar to that used in conventional liquid developers, but their formulation has been modified to be compatible with silicone oils for adjusting charging characteristics and dispersibility. The smaller the average particle size of the toner is, the better the resolution is. However, the smaller the particle size is, the larger the physical adhesive force is, and the more difficult it is to remove when transferring. Therefore, in this embodiment, the average particle diameter of the toner is adjusted so that the center is around 2 to 4 μm for the purpose of improving transferability.

The viscosity of the liquid developer depends on the carrier liquid used,
It depends on the resin, color pigment, charge control agent, etc. and their concentrations. In this example, the viscosity is 50 to 6000 m.
An experiment was conducted by changing the Pa · s and the toner concentration within the range of 5 to 40%.

The carrier liquid used is one having a low viscosity such as dimethylpolysiloxane oil or cyclic polydimethylsiloxane oil exhibiting a high electric resistance. Since the liquid developer layer formed on the developer support is formed in a thin layer, the carrier liquid contained in the liquid developer layer is extremely small, so that it is supplied to the latent image surface of the image support. The amount of carrier liquid contained in the liquid developer is extremely small. Therefore, the carrier liquid absorbed by the paper or the like during transfer is extremely small, and if the viscosity is 1000 mPa · s or less, almost no carrier liquid remains on the paper or the like after fixing. According to experiments conducted by the present inventors, the carrier liquid has a viscosity of 2.5 mPa · s, DC3 manufactured by Dow Corning Co., USA.
44 and a viscosity of 6.5 mPa · s, when the image output experiment was conducted using DC345 of Dow Corning Co., USA,
In each case, no carrier liquid remained on the paper after fixing. However, since the volatility is high, it is necessary to make the developing device have a closed structure. In addition, the carrier liquid has a viscosity of 20.
When the image output experiment was carried out using KF-96-20 manufactured by Shin-Etsu Silicon Co., Ltd., which has mPa · s, no carrier liquid remained on the paper after fixing was observed. Further, since the volatility is not so high, it is not necessary to make the developing device have a closed structure. DC344, DC345 and KF-96-2
0 is generally used for cosmetics and has high safety such as toxicity. For carrier liquid, see Shin-Etsu Silicon K
There are many other types such as F9937, and any one may be selected as long as electrical resistance, evaporation characteristics, surface tension, safety and the like are satisfied.

Further, according to experiments by the inventors, when the surface tension is large, fog or toner lumps may adhere. Experimentally, when the surface tension is 21 dyn / cm or more, there is a problem in image quality. I found it to happen easily.

The electric resistance value is preferably 10 ¹⁴ Ωcm or more because of the problem of toner charging stability. At least 1
0 ¹² Ωcm or more is necessary. In the description of the present embodiment, in view of these experimental results, the DC3 is low in price and easily available.
An example using 45 is shown.

The pre-wetting liquid easily evaporates during fixing without disturbing the electrostatic latent image formed on the image support,
It is required that fogging and lumps of toner do not adhere. For example, DC344, Dow Corning Corp.
DC200-0.65, -1.0, -2.0, KF96L-1, KF9937 manufactured by Shin-Etsu Silicon Co., and the like. Generally, it is preferable to select a highly evaporative silicone oil.

In an experiment conducted by the inventors, the liquid viscosity was 0.
The liquid was dried by development, transfer, and fixing without problems in the range of 5 to 3 mPa · s, but from 5 mPa · s to 6 mPa · s
-At about s, there was a tendency that time and temperature were required for drying the liquid at the time of fixing. If it is 10 mPa · s, the energy required for drying becomes too large, which is not general. Also,
If it is 0.5 mPa · s or less, the volatility increases, so
It is not appropriate because it is subject to legal regulations as dangerous goods. In addition, the boiling point is preferably 250 ° C. or lower because of the influence of heating the paper.

The surface tension is preferably as low as possible in order to eliminate the adhesive force between the developer and the image support, improve the releasability, prevent the image from becoming dirty, and improve the resolution of the image quality. According to experiments by the present inventors, 20 to 21 dyn / c
It is preferable to select one having a limit of about m and lower than this.

When the electric resistance is low, the latent image charge leaks and the image is blurred. Therefore, it is necessary to use the one having the highest electric resistance. Experimentally 10 ¹⁴
Ωcm or more is desirable. A minimum of 10 ¹² Ωcm is required.

Next, the operation of the electrostatic latent image liquid developing apparatus of this embodiment will be described. First, as shown in FIG. 3A, the pre-wetting liquid 220 is applied onto the photoconductor 10 by the pre-wetting device 20. The pre-wetting device 20 brings the pre-wetting liquid supply body 202 into contact with the photoconductor 10 when a control signal is input from the outside. The pre-wet liquid 220 is constantly circulated by the pump 208 inside the pre-wet liquid supply body 202, and the pre-wet liquid 220 that exceeds the pore volume of the bell eater, which is the pre-wet liquid supply body 202, is shown in FIG. Thus, it is released from the release side 202b of the pre-wet liquid supply body 202 and is released from the bottom surface of the pre-wet liquid supply body 202,
The photoconductor 10 is evenly applied on the photoconductor 10 without being scratched.

Next, as shown in FIG. 3B, the photoreceptor 10 coated with the pre-wetting liquid 220 is applied to the corona discharger 302.
Charged by. The charges carried by the ions pass through the pre-wet liquid layer and reach the surface of the photoconductor 10. Next, the image is exposed on the charged photoreceptor 10. For example, the image is exposed by a laser scanner to form an electrostatic latent image on the surface of the photoconductor 10. As shown in FIG. 3C, the portion of the laser scanner exposed to the light becomes conductive, and the charge disappears, and the portion not exposed to the light remains as an electrostatic latent image which is an image of the charge.

Then, the developing device 50 visualizes the electrostatic latent image. Liquid reservoir 5 discharged by bellows pump 502
The liquid developer 508 stored in 04 is the developing roller 50.
After being pumped up by 6, the layer thickness is adjusted by the regulating roller 510 to form a thin layer on the developing roller 506. The liquid developer layer thus formed on the developing roller 506 is brought close to the electrostatic latent image formed on the surface of the photoconductor 10 as shown in FIG. The charged toner is moved onto the photoconductor 10. The liquid developer 508 stored in the liquid reservoir 504 is agitated by the rotation of the developing roller 506.

Next, as shown in FIG. 3E, the transfer device 6
The toner image on the photoconductor 10 is transferred to a predetermined paper 604 by the electrostatic force generated by the voltage applied to the transfer roller 602 of 0.
Transfer to. Although not shown in FIG. 1, FIG.
As shown in (F), the fixing heater 704 provided in the fixing roller 702 of the fixing device thermally fuses the toner transferred to the paper 604 to fix the toner on the paper. On the other hand, the liquid developer 508 remaining on the photoconductor 10 is removed by the cleaning device 70. It should be noted that the photoconductor 10 is repeatedly used in the cycle from the pre-wet to the neutralization, after being neutralized by a neutralization device (not shown).

6 to 10 are diagrams for explaining the developing process of this embodiment in detail, FIG. 6 is a diagram for explaining the entire developing process, and FIG. 7 is a diagram showing a state of the approaching process. FIG. 8 is a diagram showing a state of toner movement process, FIG. 9 is a diagram showing a separation process of a non-image portion, and FIG. 10 is a diagram showing a separation process of an image portion. Unlike the conventional developing process, in the developing process of this embodiment, as shown in FIG. 6, a developing roller approaches a photoconductor and a liquid developer approaches a photoconductor surface, and a liquid developer layer is formed. A toner movement process in which the pre-wet liquid layer is in soft contact with the toner to move the toner, and a separation process in which the developing roller is separated from the photoconductor and is separated into toner adhering to the developing roller and toner adhering to the photoconductor. It is thought to consist of three processes.

In the approaching process, as shown in FIG. 7, since the developing roller 506 having elasticity is used, the liquid developer layer on the developing roller 506 and the pre-wet liquid layer on the photoconductor 10 come into contact with each other. The contact pressure at the time of dispersion is dispersed, and the high-viscosity liquid developer including the carrier liquid and the toner is softly contacted with the pre-wet liquid. At this time, the developing roller 50 is interposed via the liquid developer layer and the pre-wet liquid layer.
It is as if a minute gap, that is, a space d, is formed between 6 and the photoconductor 10. In addition, the pre-wet liquid having a low viscosity is slightly extruded back and forth to cause a pool of the pre-wet liquid.

In the process of moving the toner, as shown in FIG. 8, in the image portion, the toner forms a pre-wet liquid layer mainly by the Coulomb force due to the electric field formed between the charge on the photoconductor 10 and the developing roller 506. It passes and moves to the latent image surface. On the other hand, the toner in the non-image area is basically the photosensitive member 10.
Since the surface of the liquid developer and the liquid developer layer are separated by the pre-wet liquid layer, unnecessary toner does not adhere to the surface of the photoconductor 10.

In the separation process, in the non-image part, as shown in FIG.
Basically, the liquid developer remains on the developing roller 506 as shown in FIG. At the interface between the pre-wet liquid layer and the liquid developer layer, when the two layers are separated, a part of the pre-wet liquid layer having a low viscosity is transferred to the liquid developer layer and separated. Therefore, the separation point of the two layers is considered to be inside the pre-wet liquid layer. On the other hand, in the image area, as shown in FIG. 10, the toner that has moved to the surface of the photoconductor 10 displaces the pre-wet liquid layer, so that the pre-wet liquid layer is located on the toner layer and is separated in that layer. On the developing roller 506, a part of the carrier liquid and a part of the pre-wet liquid which remain after the toner moves form a layer. The pre-wetting liquid remaining on the photoconductor 10 facilitates the movement of the toner due to the electrostatic force in the subsequent transfer process.

FIG. 11 is a diagram for explaining the significance of thinning the liquid developer. If the liquid developer layer applied on the developing roller 506 is too thick, the liquid developer 508
Since the viscosity of the toner is high, a group of toners that try to move from the developing roller 506 to the surface of the photoconductor 10 by electrostatic force forms a cluster without cutting the viscosity of the toner around it, and the photoconductor 10 Since it moves to the surface of the toner, excessive adhesion of toner occurs and image noise occurs. In order to suppress the generation of these clusters, it is necessary to control the thickness of the liquid developer layer to a minimum value at which development can be sufficiently performed.

FIG. 12 is a view showing how the developer support and the photoconductor are brought into hard contact, and FIG. 13 is a view for explaining the soft contact of this embodiment.
As described above, the function of the pre-wet liquid layer for image formation is important in the developing process of this embodiment. Therefore, an important requirement in the developing process is to maintain the two-layer state of the pre-wet liquid layer and the liquid developer layer. As shown in FIG. 12, when the developer support and the photoconductor are in hard contact, the two-layer state cannot be maintained.
In this embodiment, as shown in FIG. 13, since the developing roller 506 having elasticity is used as the developer support,
When the pressing force of the developing roller 506 to the photoconductor 10 is adjusted to disperse the contact pressure when the liquid developer layer on the developing roller 506 and the pre-wet liquid layer on the photoconductor 10 are dispersed, the liquid developer is It is as if a minute gap, that is, a space d is formed between the photoconductor 10 and the developing roller 506 through the layer and the pre-wet liquid layer. Therefore, in the developing area, the liquid developer layer and the pre-wet liquid layer can be brought into contact while maintaining a two-layer state in which the layers can be distinguished from each other.

Next, optimization of the layer thickness of the liquid developer layer, the layer thickness of the pre-wet liquid layer and the development gap, that is, the gap will be described. The layer thickness of the liquid developer layer is particularly 5 when the viscosity of the liquid developer is 50 to 100 mPa · s or more.
For those of 00 mPa · s or more, it is necessary to reduce the thickness. Ideally, it should be slightly thicker than the layer thickness that satisfies the toner development amount (that is, the concentration when a large area is painted black) required at the time of development. This is because when a high-viscosity liquid developer is used, electrostatically selected toner moves onto the photoconductor along with the excess toner due to the viscosity of the liquid during development, causing abnormal toner adhesion. This is because the image is smeared and the image is stained. According to the experiments conducted by the inventors, a developer having a high toner concentration is 5 μm.
Therefore, for the toner having a low toner concentration, a good image was obtained with a layer thickness of about 40 μm. Further, when a developer having a toner concentration of 20 to 30% was used, good image quality was obtained with a toner layer thickness of about 8 to 20 μm.

The layer thickness of the pre-wet liquid layer has an optimum value depending on the viscosity and surface tension of the selected pre-wet liquid. If it is too thin, the high-viscosity liquid developer irregularly adheres to the photoconductor to cause image contamination. As the amount of pre-wetting liquid is increased, image stains are improved,
The optimum value is confirmed. When the amount is further increased, the charge of the latent image flows, the sharpness and the resolution are deteriorated, and the toner flows during development, which also tends to blur the image. D
In experiments using C344, 30 μm or less, especially 20 μm
Good results were obtained with a thickness of m or less. For those having a lower viscosity than this, good results can be obtained with a thinner thickness or a thicker thickness. However, for high viscosity ones, the optimum value tends to have a narrow range.

As in the conventional developing method, the narrower the gap between the photosensitive member and the developing roller, that is, the interval, the better the resolution and the uniformity of the density of the solid portion in the image quality. In the highly viscous liquid developer used in this example, the cohesive force between the toners is strong, and like the powder developer, the toner released from the developer support or carrier particles by mechanical impact or electrostatic force is used for the development. The phenomenon that is used does not occur. That is, development is not performed with an air layer interposed between the liquid developer layer and the photoconductor. Therefore, it is essential that the developing roller is in contact with the liquid developer layer, the liquid developer layer is in contact with the pre-wet liquid layer, and the pre-wet liquid layer is in contact with the photoconductor. Therefore, the development gap or distance d
Must have a size that is equal to or less than the thickness of the liquid developer layer and the pre-wet liquid layer and does not disturb the respective layers. In this embodiment, when the pre-wet liquid layer on the photoconductor 10 and the liquid developer layer on the developing roller 506 are brought into contact with each other depending on the hardness of the developing roller 506, the viscosity of the developer, and the difference in toner concentration, The pressing force of the developing roller 506 against the photoconductor 10 was set so that the distance d was between 8 μm and 50 μm.

Table 1 shows the results of the image forming experiment under the above-mentioned conditions. From these results, the optimum range of the developer and the viscosity of the pre-wet liquid for the developing method of this embodiment is 100 mPa · s to 6000 mPa · s for the developer.
s, pre-wetting liquid is 0.5 mPa · s to 5 mPa · s
It was found to be between s. Regarding image quality,
Although it varies depending on the thickness of the liquid developer layer on the developing roller, the thickness of the pre-wet liquid layer, the developing gap, etc., even if the developing conditions are optimized, there is a general tendency as shown in Table 1. It was confirmed that the optimum area of the liquid developer falls within the range shown in Table 1. The silicone oil of the pre-wet liquid is DC200 series manufactured by Dow Corning, and the carrier liquid of the developing liquid is DC345 of the same company.
Was used.

[0050]

[Table 1]

According to the first embodiment of the present invention, the liquid developer layer on the developing roller 506 and the pre-wet liquid on the photoreceptor 10 are rotated while the developing roller 506 having elasticity is rotated in the direction in which the photoreceptor 10 is driven. By contacting the layers,
Since the developing roller 506 elastically deforms in the developing area, the liquid developer layer on the developing roller 506 and the photosensitive member 10 are not affected.
The contact pressure at the time of contact with the upper pre-wet liquid layer can be dispersed. Therefore, in the developing area, the liquid developer layer and the pre-wet liquid layer can be brought into contact with each other while maintaining the two-layer state. Therefore, the liquid developer layer is excessively crushed and the non-image on the photoconductor 10 is crushed. It is possible to prevent the toner from adhering to the part and disturbing the image.

Further, according to the first embodiment of the present invention, the surface of the developing roller 506 is provided with the surface layer 506c formed of a conductive member which does not swell in the silicone oil which is the carrier liquid of the liquid developer 508. As a result, when the developing roller 506 elastically deforms in the developing area, the liquid developer 50
It is possible to prevent the pre-wet liquid layer on the photoconductor 10 from being disturbed by absorbing or releasing 8 and thereby,
It is possible to prevent the toner image formed on the photoconductor 10 from being disturbed.

Further, according to the first embodiment of the present invention, the contact rollers 507 for contacting the photoconductor 10 are provided on both sides of the developing roller 506, and the outer diameter of the contact roller 507 is changed to change the outer diameter of the developing roller 506. Since the pressing force to the photoconductor 10 is adjusted, the contact pressure when the liquid developer layer formed on the developing roller 506 and the pre-wet liquid layer formed on the photoconductor 10 are easily dispersed. be able to.

Further, according to the first embodiment of the present invention, the use of silicone oil as the carrier liquid of the liquid developer has the following advantages over the conventional ones.

The conventional liquid developer generally uses IsoparG (registered trademark: manufactured by Exxon) as a carrier liquid.
Since this Isopar has a resistance value not as high as that of silicone oil, when the toner concentration is increased, that is, when the distance between particles is reduced, the chargeability of the toner is deteriorated. Therefore, Isop
In the case of ar, the toner density is limited. On the contrary,
Since the silicone oil used in this embodiment has a sufficiently large resistance value, the toner concentration can be increased. Also,
Generally, in the case of Isopar, the toner is well dispersed, and therefore even if the toner concentration is 1 to 2%, the toners repel each other, so that the toner is uniformly dispersed. On the other hand, silicone oil has a toner concentration of 1 to 2%,
The dispersibility is not good and it will precipitate soon. However, when the toner concentration is set to 5 to 40%, the toner is densely packed and stably dispersed. Therefore, in this embodiment, a high-viscosity liquid developer in which toner is dispersed at high density is used. As a result, the amount of the developer can be significantly reduced as compared with the conventional low-concentration liquid developer, and the device can be downsized. Furthermore, since the liquid developer of this embodiment is a high-viscosity liquid, it is easier to store and handle than the conventional low-viscosity liquid developer or powder developer.

Isopar used in the conventional liquid developer is
As mentioned above, it is highly volatile and emits a foul odor,
There is a problem that it not only deteriorates the work environment but also causes pollution. On the other hand, the silicone oil used in this example is a safe liquid and is odorless, as is clear from the fact that it is used for cosmetics. The environment can be improved and pollution problems do not occur.

In the first embodiment, the developing roller 5
Although the one using the bellows pump 502 as a means for supplying the liquid developer 508 to 06 has been described, the present invention is not limited to this. For example, like the developing device 52 shown in FIG. 18, the double gear pump 52 in which the liquid developer 508 stored in the tank 522 is immersed in the liquid developer 508 stored in the tank 522 and arranged.
4 may be used to supply the toner to the developing roller 506 by pumping.

In the first embodiment described above, the regulation roller 510 is used to adjust the layer thickness of the liquid developer 508 applied on the developing roller 506 to form a thin layer. The present invention is not limited to this. For example, like the developing device 54 shown in FIG. 19, a regulation blade 542 formed of rubber or a rigid body is used to adjust the layer thickness of the liquid developer 508 applied on the developing roller 506 to form a thin layer. You may In the experiments conducted by the present inventors, the regulation blade 542 and the developing roller 50
6, the contact is made in the trail direction, and the tip of the regulation blade 542 is connected to the regulation blade 542 and the developing roller 506.
By designing to be longer than the contact position with
It was possible to form a stable developer thin layer.

Further, in the above-mentioned first embodiment, the pre-wetting liquid 22 is applied onto the photoconductor 10 by the pre-wetting device 20.
Although the case where the photoreceptor 10 is charged by the charging device 30 after applying 0 is described, the present invention is not limited to this. The application of the pre-wet liquid 220 may be performed before the developing process.

Next, a second embodiment of the present invention will be described with reference to FIG. 20 is a schematic configuration diagram of a liquid developing device for an electrostatic latent image which is a second embodiment of the present invention. Here, the reference numerals in the drawings are the same as those having the same functions as those in the first embodiment.

As shown in FIG. 20, the electrostatic latent image liquid developing apparatus according to the second embodiment of the present invention coats the photoconductor 10 as the image support and the prewetting liquid on the photoconductor 10. A pre-wetting device 20, a charging device 30 that charges the photoconductor 10, and an exposure device 40 that exposes an image on the photoconductor 10.
And a developing device 55 that visualizes the electrostatic latent image by supplying toner to the portion of the photoconductor 10 where the electrostatic latent image is formed.
Then, a transfer device 65 that transfers and fixes the toner on the photoconductor 10 to a predetermined paper, a paper feeding device 610 that conveys the predetermined paper to the transfer device 65, and removes the toner remaining on the photoconductor 10. The cleaning device 70 and the static eliminator 80 that neutralizes the charged photoconductor 10 are provided.

The electrostatic latent image liquid developing device of the second embodiment differs from the liquid developing device of the first embodiment in a developing device 55 and a transfer device 65. Other parts are the same as those of the first embodiment, or the conventional technology used in the conventional electrophotographic printer can be applied in most cases. Therefore, in this embodiment, the developing device 55 and the transfer device 65 will be described in detail, and the description of other parts will be omitted.

The developing device 55 of the second embodiment comprises a developing roller 556 which is a developer support, a supplying device 56 which applies the liquid developer 508 to the developing roller 556, and a liquid which adheres to the developing roller 556 after development. A scraping blade 557 for removing the developer 508 is provided.

The supply device 56 is provided with four developing cartridges 56a, 56b, 56c, 56d (hereinafter, also simply referred to as developing cartridges) provided on a rotary shaft 559. Each developing cartridge includes a tank 552 for storing the liquid developer 508, a supply roller 552a provided at an outlet of the tank 552, a conveyance roller 554 provided so as to abut the supply roller 552a, and a conveyance roller 5
54 and a coating roller 555 provided so as to abut. The liquid developer 508a containing yellow toner is stored in the tank 552 of the developing cartridge 56a, and the liquid developer 508b containing magenta toner is stored in the tank 552 of the developing cartridge 56b.
The liquid developer 508c containing cyan toner is stored in the tank 552 of c, and the liquid developer 508d containing black toner is stored in the tank 552 of the developing cartridge 56d.
Are stored respectively (hereinafter, simply liquid developer 59
8a to 508d are also referred to as liquid developers 508). The supply device 56 rotates the rotary shaft 559 to rotationally move the developing cartridge, so that the coating roller 555 of one of the developing cartridges is brought into contact with the developing roller 556.
As a result, the liquid developer 508 containing the toner of the desired color is applied to the developing roller 556.

The supply roller 552a is a conveyance roller 554.
The liquid developer 508 is supplied to the transport roller 554 by rotating in the direction opposite to the rotation direction of the. Conveyor roller 5
By rotating the coating roller 555 in a direction opposite to the rotation direction of the coating roller 555, the coating roller 555 is supplied to the coating roller 552.
The liquid developer 508 supplied by a is conveyed. The application roller 555 rotates in a direction opposite to the rotation direction of the developing roller 556 to apply the liquid developer 508 carried by the carrying roller 554 to the surface of the developing roller 556. The feed roller 554 and the coating roller 555 were used to supply the liquid developer 508 to the developing roller 556 because the liquid developer 508 is a toner in which the toner is dispersed in a high concentration, and therefore a large amount of developer is required. This is because it is necessary to apply a small amount of liquid developer to the surface of the developing roller 556 thinly and evenly. The transport roller 55
One or a plurality of transport rollers for transporting the liquid developer 508 may be provided between the coating roller 4 and the coating roller 555.

The developing roller 556 supplies the liquid developer 508 to the latent image surface of the photoconductor 10 by rotating in the direction opposite to the rotation direction of the photoconductor 10. The developing roller 55
Similar to the developing roller 506 of the first embodiment, 6 is required to have elasticity and conductivity. Therefore, the developing roller 5
Detailed description of 56 is omitted.

The transfer device 66 of the second embodiment comprises an intermediate transfer belt 652 which is an intermediate transfer member, and an intermediate transfer belt 652.
Rollers 654a, 654b, 654 for rotating and driving
c and holding rollers 655a and 655b for holding a part of the intermediate transfer belt 652 so as to abut on the photoconductor 10.
And a corona discharger 656 for charging the intermediate transfer belt 652 with a charge having a polarity opposite to that of the toner, and a secondary transfer roller 653 which is a secondary transfer member provided so as to be separable from and in contact with the intermediate transfer belt 652. ing.

The intermediate transfer belt 652 is driven by the drive roller 65.
4a, 654b, 654c rotate in the direction opposite to the rotation direction of the photoconductor 10. The intermediate transfer belt 652 has
A flexible belt member such as a metal belt such as a seamless nickel belt, a polyimide film belt, a resin belt such as a PET film belt, or a rubber belt is used. Thereby, the contact pressure when the toner image formed on the photoconductor 10 and the intermediate transfer belt 652 contact each other can be dispersed. When a resin belt or a rubber belt is used, it is necessary to make the surface of the belt conductive or add conductive fine particles to the material of the belt to obtain a desired electric resistance value.

On the intermediate transfer belt 652, a surface layer having a good releasing property such as Teflon or silicon is formed. This is to weaken the physical adhesion of the toner to the intermediate transfer belt 652 and facilitate the movement of the toner to the paper.

The secondary transfer roller 653 rotates in a direction opposite to the rotation direction of the intermediate transfer belt 652, so that the paper conveyed by the paper feeding device 610 is transferred.
It is fed between 52 and the secondary transfer roller 653. At this time, the secondary transfer roller 653 is pressed against the intermediate transfer belt 652 via the paper. A secondary transfer bias is applied to the secondary transfer roller 653 to transfer the toner image formed on the intermediate transfer belt 652 to the paper. Then, the toner image is fixed on the paper by a fixing device (not shown). A fixing heater may be provided inside the driving roller 654a to heat the toner on the intermediate transfer belt 652 so that the toner image formed on the intermediate transfer belt 652 is transferred onto the paper and fixed at the same time. . The fixing heater may be provided in both the driving roller 654a and the secondary transfer roller 653.

Next, the operation of the liquid developing apparatus for electrostatic latent images according to the second embodiment of the present invention will be described. In the electrostatic latent image liquid developing device of this embodiment, first, the photoconductor 10 is charged by the charging device 30, the image is exposed on the photoconductor 10 by the exposure device 40, and then the photoconductor 1 is made by the pre-wetting device 20.
The pre-wet liquid 220 is applied to the surface of No. 0. Next, the electrostatic latent image formed on the photoconductor 10 is visualized by the developing device 55. Liquid developer 5 stored in tank 552
08 is a conveyance roller 554 by the supply roller 552a.
Is supplied to the coating roller 55 by the transport roller 554.
After being conveyed to No. 5, the developing roller 556 is coated by the coating roller 555. The liquid developer 508 thus conveyed to the developing roller 556 via the roller is thinly and evenly applied to the developing roller 556 to form a thin layer on the developing roller 556. The supply device 56 rotates the rotary shaft 559 to rotationally move the developing cartridge,
The coating roller 555 of any of the developing cartridges 56a to 56d is brought into contact with the developing roller 556. This allows
A liquid developer 508 containing any one of yellow, magenta, cyan, and black toners is thinly and evenly applied to the developing roller 556.

Next, the liquid developer layer formed on the developing roller 556 is brought close to the electrostatic latent image formed on the surface of the photoconductor 10, and the electrostatically applied force causes the charged toner on the photoconductor 10. It is moved to form a toner image.

Next, the toner image formed on the photoconductor 10 by the transfer device 65 is primarily transferred onto the intermediate transfer belt 652 which is an intermediate transfer member. The toner image formed on the photoconductor 10 is an electrostatic force generated between the toner image formed on the photoconductor 10 and the intermediate transfer belt 652 charged by the corona discharger 656 with a charge having a polarity opposite to that of the toner. As a result, it moves onto the intermediate transfer belt 652 and is primarily transferred. On the other hand, in the photoconductor 10, the liquid developer 508 remaining on the photoconductor 10 is removed by the cleaning device 70,
After that, the charge is removed by the charge removing device 80. Then, after rotating the developing cartridge to switch the developing cartridge abutting on the developing roller 556, the above cycle from the charging to the discharging is repeated again, whereby yellow, magenta, cyan and black are transferred onto the intermediate transfer belt 652. Toner images are transferred one after another. This allows
A toner image corresponding to colorization is formed on the intermediate transfer belt 652.

Next, the transfer device 65 secondarily transfers the toner image formed on the intermediate transfer belt 652, which corresponds to colorization, onto a paper as a recording medium. Intermediate transfer belt 652
The color-formed toner image formed above has a surface layer with good releasability due to the pressing force of the secondary transfer roller 653 on the intermediate transfer belt 652 and the bias voltage applied to the secondary transfer roller 653. Intermediate transfer belt 652 having
Away from the intermediate transfer belt 652 and the secondary transfer roller 6
The sheet 53 is moved by a sheet feeding device 610 between the sheet 53 and the sheet 53 and is secondarily transferred. After that, a fixing device (not shown) thermally fuses and fixes the color-transferred toner image secondarily transferred onto the paper. Thereby, a color image can be formed on the paper. When a fixing heater is provided inside the drive roller 654a and / or the secondary transfer roller 653 to heat the toner on the intermediate transfer belt 652, the toner image formed on the intermediate transfer belt 652 is transferred onto paper at the same time. Can be established.

According to the second embodiment of the present invention, a plurality of developing cartridges 56a to 56d for supplying the color liquid developers 508a to 508d to the developing roller 556 are rotationally moved and switched to sequentially develop one developing cartridge. By contacting the roller 556 and developing, only one developer support is required, and therefore the liquid developing device for electrostatic latent images corresponding to color can be downsized.

In the second embodiment described above, as the developing device, the developing cartridge 56a fixed to the rotary shaft 559 is used.
It has been described that the coating roller 555 of one developing cartridge is brought into contact with the developing roller 556 sequentially by rotationally moving and switching between ~ 56d to 56d, but the present invention is not limited to this. The developing device may be any device that can selectively abut the developing cartridges 56a to 56d on the developing roller 556. For example, the developing cartridges 56a to 56d are moved in parallel and switched, and the application roller 555 of one developing cartridge is sequentially changed to the developing roller 556.
May be in contact with.

Further, in the second embodiment, as the developing device, the developing cartridge 56a for supplying the liquid developer 508a containing the yellow toner to the developing roller 556,
The developing cartridge 56b for supplying the liquid developer 508b containing magenta toner to the developing roller 556, and the liquid developer 508c containing cyan toner for the developing roller 556.
However, the present invention is not limited to this, although the developing cartridge 56c for supplying the toner to the developing roller 56 and the developing cartridge 56d for supplying the liquid developer 508d containing the black toner to the developing roller 556 have been described. The developing device may be provided with two or three developing cartridges for supplying a liquid developer containing a toner of a desired color to the developing roller, if necessary.

Further, in the second embodiment, as the developing cartridge of the developing device, the liquid developer 508 supplied to the conveying roller 554 by the supplying roller 552a is conveyed to the applying roller 555 and then applied to the developing roller 556. However, the present invention is not limited to this. The developing cartridge may be one that supplies the liquid developer 508 to the developing roller using a roller. Further, the means for supplying the liquid developer 508 to the transport roller 554 is not limited to the supply roller 552a, and for example, the transport roller 5 may be a bellows pump.
It may be supplied to 54.

Further, in the second embodiment, the liquid developer 508 attached to the developing roller 556 is used as the developing device.
Although the scraping blade 557 is used to remove the scraping blade, the present invention is not limited to this.
The developing device may be one in which the liquid developer 508 attached to the developing roller is removed by a scraping roller provided in contact with the developing roller.

In the second embodiment described above, the exposure device 4
Although the pre-wetting device 20 applies the pre-wetting liquid 220 onto the photoreceptor 10 after the image is exposed by 0, the present invention is not limited to this. The application of the pre-wet liquid 220 may be performed before the developing process.

In the second embodiment, as a transfer device, the toner image formed on the photoconductor 10 is primarily transferred to the intermediate transfer body, and then the toner image primarily transferred to the intermediate transfer body is used as a recording medium. I explained about the second transfer to
The present invention is not limited to this, as long as the toner image formed on the photoconductor 10 can be transferred to a recording medium. In addition, although the electrostatic transfer was explained as the primary transfer onto the intermediate transfer member, it may be adhesive transfer using an adhesive.

The present invention is not limited to the above embodiments, but various modifications can be made within the scope of the gist thereof. For example, in each of the above-described embodiments, the pre-wet liquid 220 is the pre-wet liquid supply body 2 as the pre-wet device.
However, the present invention is not limited to this, and the pre-wetting device supplies the pre-wetting liquid to the pre-wetting liquid supply body only during pre-wetting. Good.

FIG. 14 is a diagram showing a modification of the pre-wetting device used in the liquid electrostatic latent image developing device in each of the above-described embodiments. Prewetting device 20 shown in FIG.
a is a case 8 that houses a plate-shaped pre-wet liquid supply body 802 having a length substantially the same as the image width drawn on the photoconductor 10 and a supply side 802 a of the pre-wet liquid supply body 802.
04 and a tank 806 for storing the pre-wet liquid 220
A pump 808 for pumping the pre-wet liquid 220 stored in the tank 806 based on a signal from the outside, a tube 810, and a displacement device (not shown).
The tube 810 conveys the pre-wet liquid 220 pumped up by the pump 808 to the supply side 802 a of the pre-wet liquid supply body 802. A space is formed between the supply side 802a of the pre-wet liquid supply body 802 and the case 804, and the pre-wet liquid 220 is stored in this space and then supplied from the supply side 802a. When a signal is not input from the outside, the displacement device, as shown in FIG.
Is held at a position away from the photoconductor 10, and when a signal is input from the outside, the pre-wet liquid supply body 802 is brought into contact with the photoconductor 10 as shown in FIG. When a signal is input from the outside, the pre-wet device 20a supplies the pre-wet liquid 220 to the pre-wet liquid supply body 802 by the pump 208, and the discharge side 802b of the pre-wet liquid supply body 802 by the displacement device. Abut. The pre-wet liquid supply body 802 is a pre-wet liquid supply body 802 that exceeds the pore volume of BELLITA (registered trademark: Kanebo Corporation).
Is discharged from the discharge side 802b and is applied onto the photoconductor 10. This makes it possible to apply the pre-wetting liquid with a uniform thickness without damaging the surface of the photoconductor.

If the pore volume of the bell eater used for the pre-wet liquid supply body is large, the amount of the pre-wet liquid held by the pre-wet liquid supply body increases, so that the pre-wet liquid supplied to the pre-wet liquid supply body is increased. There is a time lag between the start of the supply and the start of the application of the pre-wet liquid to the surface of the photoconductor. Therefore, it is desirable that the length of the pre-wet liquid supply body 802 is as short as possible in the flow direction of the pre-wet liquid 220.

In each of the above-described embodiments, the pre-wetting device has been described in which the pre-wetting liquid is applied to the surface of the photosensitive member by the pre-wetting liquid supply body formed of the continuous porous body. Is not limited to this. The pre-wetting device may be one that can apply a constant amount of the pre-wetting liquid to the surface of the photoconductor uniformly. For example, it may be applied by discharging the pre-wet liquid from a plurality of nozzles arranged in the axial direction, applied by a sponge roller, or applied by a rubber roller. Good.

Furthermore, in each of the above embodiments, the pre-wetting liquid containing silicon as a main component has been described, but the present invention is not limited to this, and the viscosity of the pre-wetting liquid is 0.5 to 5. Silicon may not be the main component as long as it has an electric resistance of 10 ¹² Ωcm or more, a boiling point of 100 to 250 ° C., and a surface tension of 21 dyn / cm or less. Furthermore, when the surface of the image support is coated with a material having releasability, a pre-wetting device is not particularly required.

Furthermore, in each of the above-mentioned embodiments, the case where the organic photoreceptor is used as the image support has been described, but the present invention is not limited to this, and the image support is
It may be an electrostatic recording paper such as an electrostatic plotter, or an electrophotographic recording medium in which an insulating layer is formed on a conductor that directly forms an electrostatic latent image such as various photoconductors used in the Carlson method or ionography.

The present invention is not limited to the above embodiments, and the viscosity of the highly viscous developer may be 10,000 mPa · s as long as the layer thickness of the developer is 5 to 40 μm. At present, a developer with a high viscosity of 6000 mPa · s or more is difficult to agitate between the carrier liquid and the toner, so it is thought to be costly. However, if it becomes available at a low cost, it will be even at 6000 mPa · s or more. Good. If the viscosity exceeds 10,000 mPa · s, it becomes unrealistic. The carrier liquid of the liquid developer is not limited to silicone oil.

[0089]

As described above, according to the liquid latent electrostatic image developing method of the present invention, the developer support is supported while rotating the elastic cylindrical developer support in the direction of following the image support. By bringing the liquid developer layer on the body into contact with the image support, the contact pressure when the liquid developer layer on the developer support comes into contact with the image support can be dispersed. In the above, it is possible to prevent the liquid developer layer on the developer support from being excessively crushed and the toner from adhering to the non-image portion on the image support to disturb the image, and also to disperse the toner in a high concentration. It is possible to provide a liquid developing method for an electrostatic latent image, which has a high resolution, can be easily downsized, and can be reduced in pollution by developing a thin layer of the liquid developer.

A roller having an outer diameter slightly smaller than the outer diameter of the developer support is provided on both sides of the developer support, and the roller is brought into contact with the image support to bring the developer support into pressure contact with the image support. To provide a liquid developing method for an electrostatic latent image, which can easily adjust the contact pressure when the liquid developer layer on the developer support and the image support are brought into contact with each other when adjusting the force. You can

When at least the surface of the developer support is formed of a conductive member that does not absorb the liquid developer,
When the liquid developer layer on the developer support and the image support are in contact with each other and the developer support is elastically deformed, the developer support absorbs or releases the liquid developer to form a liquid. It is possible to provide a liquid developing method for an electrostatic latent image, which can prevent the developer layer from being disturbed, and thereby can effectively prevent the image from being disturbed.

Furthermore, when a developer support having a foam inside is used as the developer support, a liquid having an electrostatic latent image can relatively easily obtain a developer support having a desired hardness. A developing method can be provided.

Further, when a pre-wet process for applying a pre-wet liquid which is a dielectric liquid having releasability and which is chemically inactive is provided prior to the developing process, in the present invention, the developer support is carried out. Since the body having elasticity is used, the liquid developer layer on the developer support and the pre-wet liquid layer on the image support can be brought into contact with each other while maintaining a two-layer state in the developing region. Therefore, since the liquid developer layer contacts the surface of the image support through the pre-wet liquid layer, it is possible to more effectively prevent the toner from adhering to the non-image portion on the image support and disturbing the image. It is possible to provide a liquid developing method for electrostatic latent image.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a liquid developing device for an electrostatic latent image that is a first embodiment of the present invention.

FIG. 2 is a schematic perspective view of a pre-wetting device used in the electrostatic latent image liquid developing device shown in FIG.

FIG. 3 is a diagram for explaining the operation of the liquid latent image developing device shown in FIG.

FIG. 4 is a diagram for explaining the operation of the pre-wetting device shown in FIG.

FIG. 5 is a diagram for explaining the flow of the pre-wet liquid when the pre-wet liquid supply body is in contact with the photoconductor.

FIG. 6 is a diagram for explaining the entire developing process.

FIG. 7 is a diagram showing a state of an approaching process.

FIG. 8 is a diagram showing a state of a toner movement process.

FIG. 9 is a diagram showing a separation process of a non-image portion.

FIG. 10 is a diagram showing a process of separating an image portion.

FIG. 11 is a diagram for explaining the significance of thinning the liquid developer.

FIG. 12 is a diagram showing how the developing roller and the photoconductor are brought into hard contact with each other.

FIG. 13 is a diagram for explaining a soft contact used in the method of the present invention.

FIG. 14 is a diagram showing a modification of the pre-wetting device shown in FIG.

15 is a schematic diagram of a developing device used in the liquid developing device for the electrostatic latent image shown in FIG.

16 is a schematic view of a developing roller used in the developing device shown in FIG.

FIG. 17 is a diagram for explaining a method of bringing the photoconductor and the developing roller into contact with each other.

FIG. 18 is a diagram showing a modification of the developing device shown in FIG.

FIG. 19 is a diagram showing a modification of the developing device shown in FIG.

FIG. 20 is a schematic configuration diagram of an electrostatic latent image liquid developing device that is a second embodiment of the present invention.

[Explanation of symbols]

10 Photoconductor 20, 20a Pre-wet device 30 Charging device 40 Exposure device 50, 52, 54, 55 Developing device 56 Supplying device 56a, 56b, 56c, 56d Developing cartridge 60, 65 Transfer device 70 Cleaning device 80 Eliminating device 202, 802 Pre-wet liquid supply body 204,804 Case 206,522,552,806 Tank 208,808 Pump 210a, 210b, 810 Tube 212 Displacement device 220 Pre-wet liquid 302,656 Corona discharger 502 Bellows pump 504 Liquid reservoir 506,556 Development Roller 506a Core metal 506b Cylindrical body 506c Surface layer 507 with a roller 508, 508a, 508b, 508c, 508d
Liquid developer 510 Control roller 512, 557 Scraping blade 524 Double gear pump 542 Control blade 552a Supply roller 554 Conveying roller 555 Application roller 559 Rotating shaft 602 Transfer roller 604 Paper 610 Paper feeding device 652 Intermediate transfer belt 653 Secondary transfer roller 654a, 654b, 654c Drive roller 655a, 655b Holding roller 702 Fixing roller 704 Fixing heater

Claims (18)

[Claims] 1. A liquid developing method for an electrostatic latent image, which comprises developing an electrostatic latent image formed on an image support with toner, which is a charged image-forming particle, wherein the developer is a columnar developer having elasticity. A thin layer of a high-viscosity liquid developer in which toner is dispersed in an insulating liquid at a high concentration is formed on a support, and the developer support is rotated while being driven in a direction following the image support. An electrostatic latent image forming step, comprising a step of supplying the liquid developer to the latent image surface of the image support by bringing the liquid developer layer on the developer support into contact with the image support. Image liquid development method. 2. A roller having an outer diameter slightly smaller than an outer diameter of the developer support is provided on both sides of the developer support, and the roller of the developer support is abutted on the image support. The liquid developing method for an electrostatic latent image according to claim 1, wherein the pressure contact force to the image support is adjusted. 3. The liquid developing method for an electrostatic latent image according to claim 1, wherein the developer support has a hardness of 5 to 60 degrees JIS-A. 4. The electrostatic latent image liquid according to claim 1, wherein at least the surface of the developer support is formed of a conductive member that does not absorb the liquid developer. Development method. 5. The liquid developing method for an electrostatic latent image according to claim 1, wherein the developer support has a foam inside thereof. 6. A pre-wetting step of applying a pre-wetting liquid, which is a dielectric liquid having releasability and chemically inert, onto the image support prior to the developing process. 6. The liquid developing method for an electrostatic latent image according to claim 1, 2, 3, 4 or 5. 7. The pre-wetting liquid has a viscosity of 0.5 to
5 mPa · s, electric resistance 10 ¹² Ωcm or more, boiling point 1
The liquid developing method for an electrostatic latent image according to claim 6, wherein the surface tension is from 00 to 250 ° C and 21 dyn / cm or less. 8. The liquid developing method for an electrostatic latent image according to claim 7, wherein the pre-wetting liquid contains silicon oil as a main component. 9. The high-viscosity liquid developer having a viscosity of 100 to 10,000 mPa · s is used, and the high-viscosity liquid developer on the developer support has a thickness of 5 to 40.
It is regulated to μm, Claims 1, 2,
3. A liquid developing method for an electrostatic latent image according to 3, 4, 5, 6, 7 or 8. 10. The liquid developer has an insulating liquid viscosity of 0.5 to 1000 mPa · s and an electric resistance of 10 ¹² Ωc.
m or more, surface tension 21 dyn / cm or less, boiling point 10
10. The liquid developing method for an electrostatic latent image according to claim 9, wherein the temperature is 0 ° C. or higher. 11. The liquid developing method for an electrostatic latent image according to claim 10, wherein the liquid developer uses silicon oil as an insulating liquid. 12. The liquid developer has an average particle size of 0.1 to 0.1.
The liquid developing method for an electrostatic latent image according to claim 9, 10 or 11, wherein the toner contains 5 µm of toner at a concentration of 5 to 40%. 13. A liquid developing device for an electrostatic latent image, which develops an electrostatic latent image formed on an image support with toner, which is a charged image-forming particle, and is a cylindrical developer having elasticity. A thin layer of a high-viscosity liquid developer in which toner is dispersed in an insulating liquid at a high concentration is formed on a support, and the developer support is rotated while being driven in a direction following the image support. An electrostatic latent device comprising a developing means for supplying the liquid developer to the latent image surface of the image support by bringing the liquid developer layer on the developer support into contact with the image support. Image liquid developing device. 14. A roller having an outer diameter slightly smaller than an outer diameter of the developer support is provided on both sides of the developer support, and the roller of the developer support is contacted by contacting the roller with the image support. 14. The liquid developing device for an electrostatic latent image according to claim 13, further comprising an adjusting mechanism for adjusting a pressure contact force to the image support. 15. The developer support has a hardness of 5 to 60.
15. The method according to claim 13 or 1, wherein the degree is JIS-A.
4. The electrostatic latent image liquid developing device described in 4. 16. The electrostatic latent image liquid according to claim 13, wherein at least the surface of the developer support is formed of a conductive member that does not absorb the liquid developer. Development device. 17. The developer support according to claim 13, wherein the developer support has a foam inside.
15. The electrostatic latent image liquid developing device described in 15 or 16. 18. A pre-wetting means for applying a pre-wetting liquid, which is a dielectric liquid having releasability and chemically inert, onto the image support.
3, 14, 15, 16 or 17, the electrostatic latent image liquid developing device.