JP3292266B2 - Liquid developing device for electrostatic latent images - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to electrophotography, electrostatic recording,
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid developing method and a liquid developing apparatus for an electrostatic latent image formed by visualizing 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 developing apparatus for developing an electrostatic latent image formed on an image support with toner, which is charged visualized particles, a non-image forming apparatus on the image support is used. There is known a means for applying a pre-wet liquid, which is a dispersion medium of a liquid developer, to an image support prior to a developing step in order to prevent toner from adhering to a portion and disturbing an image. Further, a means for supplying a liquid developer to the latent image surface of the image support using a sponge roller for the developer support has been considered.

[0003]

By the way, in a conventional large-sized electrostatic recording apparatus or the like, generally, an organic solvent such as Isopar G is used.
(Registered trademark: manufactured by Exxson) uses a low-viscosity liquid developer in which a toner is mixed at a ratio of about 1 to 2%, and a high-concentration and high-viscosity liquid developer in which the adhesion to an image support increases. Agent (100 to 100% dispersion of toner in insulating liquid)
In the case where a high-viscosity liquid developer of 10,000 mPa · s is used, it is not clear what means is suitable as a means for preventing toner from adhering to a non-image portion on the image support.

[0004]

The present invention has been made based on the above circumstances, and relates to a case where a developer layer formed on a developer support and a pre-wet liquid layer formed on an image support come into contact with each other in a development space. In addition, a liquid developing device for an electrostatic latent image capable of preventing the pre-wet liquid layer from being disturbed, and thus preventing the toner from adhering to the non-image portion on the image support and disturbing the image. It is intended to provide.

[0005]

According to a first aspect of the present invention, there is provided a liquid developing apparatus for an electrostatic latent image, comprising the steps of: charging an electrostatic latent image formed on an image support; A liquid developing device for an electrostatic latent image to be developed with toner as visualized particles, wherein a pre-wet liquid which is a chemically inactive dielectric liquid having a releasable property on the image support. A pre-wetting means for applying, a substantially cylindrical developer support formed of a conductive and flexible thin plate member, and a rotation of the developer support provided inside the developer support; A drive roller for driving; and a guide member that contacts the image support by bending the developer support by contacting both ends of the drive roller via the developer support. High concentration of toner dispersed in insulating liquid on Developing means for applying a high-viscosity liquid developer, supplying the high-viscosity liquid developer to a latent image surface of the image support by bending and contacting the developer support with the image support; It is characterized by having.

According to a second aspect of the present invention, in the liquid developing apparatus for an electrostatic latent image according to the first aspect, perforations are provided at both ends of the developer support, and both ends of the drive roller are provided at both ends. A sprocket that meshes with the perforation is provided.

According to a third aspect of the present invention, there is provided a liquid developing device for an electrostatic latent image according to the first or second aspect of the present invention, wherein a lattice-shaped groove or projection is formed on the surface of the driving roller. It is assumed that.

According to a fourth aspect of the present invention, there is provided a liquid developing device for an electrostatic latent image according to the first, second or third aspect of the present invention, wherein a contact roller is provided on both sides of the drive roller to contact the image support. And a pressure adjusting mechanism for adjusting the pressure of the developer support against the image support by changing the outer diameter of the contact roller.

According to a fifth aspect of the present invention, there is provided a liquid developing apparatus for an electrostatic latent image according to the first, second, third or fourth aspect of the present invention, wherein the liquid developer is provided between the developer support and the image support. A low impedance circuit is formed.

According to a sixth aspect of the present invention, there is provided a liquid developing apparatus for an electrostatic latent image according to the first, second, third or fourth aspect of the present invention, wherein the high viscosity liquid developer has a viscosity of 10%.
The high-viscosity liquid developer supplied to the developer support surface has a thickness of 5 to 10,000 mPa · s.
It is characterized by being regulated to 規 制 40 μm.

According to a seventh aspect of the present invention, in the liquid developing device for an electrostatic latent image according to the sixth aspect, the liquid developer has an insulating liquid having a viscosity of 0.5 to 1000 mPa.
・ S, electric resistance is more than 10 ¹² Ωcm, surface tension is 21d
yne / cm or less and a boiling point of 100 ° C. or more.

According to an eighth aspect of the present invention, there is provided a liquid developing apparatus for an electrostatic latent image according to the seventh aspect, wherein the liquid developer uses silicon oil as an insulating liquid. It is a feature.

According to a ninth aspect of the present invention, there is provided a liquid developing apparatus for an electrostatic latent image according to the sixth or seventh aspect, wherein the liquid developer has a toner having an average particle diameter of 0.1 to 5 μm. At a concentration of 5 to 40%.

According to a tenth aspect of the present invention, in the liquid developing device for an electrostatic latent image according to the sixth aspect, the prewet liquid has a viscosity of 0.5 to 5 mP.
a · s, electric resistance is 10 ¹² Ωcm or more, boiling point is 100 ~
It is characterized in that the temperature is 250 ° C. and the surface tension is 21 dyne / cm or less.

According to a eleventh aspect of the present invention, there is provided the liquid developing method for an electrostatic latent image according to the tenth aspect, wherein the pre-wet liquid contains silicone oil as a main component. Is what you do.

[0016]

In the liquid developing device for an electrostatic latent image according to the first aspect of the present invention, since the developer support is bent and brought into contact with the image support, the electrostatic latent image is formed on the developer support. The contact pressure when the developer layer and the pre-wet liquid layer formed on the image support come into contact with each other can be dispersed. Therefore, the developer layer and the pre-wet liquid layer can be brought into contact with each other while maintaining a two-layer state in the development process, and at the end of the development process, both are separated inside the pre-wet liquid layer, It is possible to prevent the pre-wet liquid layer from being disturbed, thereby preventing the toner from adhering to the non-image portion on the image support and disturbing the image. Further, since the liquid developer in which the toner is dispersed at a high concentration is used, the amount of the liquid can be much smaller than that of a conventional liquid developer having a low concentration.

The liquid developing device for an electrostatic latent image according to claim 2, wherein perforations are provided at both ends of the developer support, and sprockets meshing with the perforations are provided at both ends of the drive roller. The developer support can be stably rotated.

The liquid developing device for an electrostatic latent image according to the third aspect has the same effect as the invention according to the second aspect by forming a lattice-shaped groove or projection on the surface of the drive roller.

According to a fourth aspect of the present invention, there is provided the liquid developing device for electrostatic latent images, wherein a contact roller is provided on both sides of the drive roller to contact the image support, and the developing roller is formed by changing an outer diameter of the contact roller. By providing a pressure adjusting mechanism for adjusting the pressing force of the developer support to the image support, the developer layer formed on the developer support and the pre-wet liquid layer formed on the image support The contact pressure at the time of contact can be easily adjusted.

According to a fifth aspect of the present invention, in the liquid developing apparatus for an electrostatic latent image, a low impedance circuit is formed between the developer support and the image support so that the toner image on the developer support is formed. Movement to the support holder can be facilitated.

The operation of the liquid developing device for electrostatic latent images according to the sixth aspect is the same as that of the first aspect. When the viscosity of the liquid developer is 10,000 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 developer. Therefore, 1000
A liquid developer of 0 mPa · s or more becomes unsuitable in terms of cost and is not realistic. On the other hand, when the pressure is 100 mPa · s or less, the toner concentration is lowered and the dispersibility of the toner is deteriorated. The layer thickness of the liquid developer needs to be thin when the toner concentration is high and thick when the toner concentration is low. Also,
Higher viscosity requires thinner. However, if the layer thickness is 4
If the thickness is larger than 0 μm, excessive toner adhesion occurs and image noise occurs. On the other hand, when the layer thickness is less than 5 μm, unevenness occurs when a solid black image is output.

In the liquid developing apparatus for an electrostatic latent image according to the present invention, by using an insulating liquid having the above characteristics,
A high-viscosity liquid developer can be obtained. Since the liquid developer formed on the developer support is formed in a thin layer,
Since the amount of the insulating liquid contained in the liquid developer layer is extremely small, the amount of the insulating liquid contained in the liquid developer supplied to the latent image surface of the image support is also extremely small. Therefore, the amount of insulating liquid absorbed by paper or the like at the time of transfer is extremely small, and the problem of adhesion of the insulating liquid to paper or the like does not particularly occur if the viscosity is 1000 mPa · s or less. However, if the viscosity is 0.5 mPa · s or less, the volatility becomes high, and it is unsuitable because it is treated as a dangerous substance. When the insulating liquid has a boiling point of 100 ° C. or lower, the amount of evaporation increases, so there is a problem in the method of storing the developer, the entire apparatus must be sealed, and it is difficult to improve the working environment. Become. When the electric resistance is less than 10 ¹² Ωcm, the insulation property is deteriorated, and the toner has a problem of conductivity and cannot be used as a developer. Therefore, the electric resistance is desirably as high as possible. Surface tension is 21 dyne / cm
Above this, the wettability deteriorates and the familiarity with the pre-wet liquid deteriorates. Therefore, it is desirable that the surface tension be as low as possible.

In the liquid developing device for an electrostatic latent image according to the eighth aspect, the insulating liquid having silicon oil as a main component can provide the insulating liquid having the characteristics according to the seventh aspect. it can.

According to a ninth aspect of the present invention, there is provided a liquid developing device for an electrostatic latent image, wherein the liquid developer contains a toner having an average particle diameter of 0.1 to 5 μm.
When the toner is contained at a concentration of about 40%, a liquid developer in which the toner is dispersed at a high concentration in the insulating liquid can be obtained. Further, the resolution is improved substantially in inverse proportion to the size of the particle size of the toner. Normally, the toner is present as a lump of about 5 to 10 pieces on the printed paper, so if the average particle diameter of the toner is 5 μm or more,
Resolution deteriorates. On the other hand, the average particle size of the toner is 0.1 μm.
If it is less than m, the physical adhesive strength becomes large, and it becomes difficult to peel off the toner during transfer.

In the liquid developing device for an electrostatic latent image according to the tenth aspect, since the characteristics of the pre-wet liquid are as described above, it is possible to obtain a pre-wet liquid having releasability and good insulating properties. it can. Since the pre-wet liquid is absorbed by paper or the like at the time of transfer, it must be evaporated at the time of fixing. For this reason, the viscosity should be 0.5 to
5 mPa · s is desirable. If the viscosity is 5 mPa · s or more, evaporation becomes difficult, and if the viscosity is 0.5 mPa · s or less, the volatility becomes high.
If the boiling point is lower than 100 ° C., the amount of evaporation increases, so that there is a problem in the preserving method of the pre-wet liquid, so that the entire apparatus must have a closed structure and it is difficult to improve the working environment. On the other hand, if the boiling point is higher than 250 ° C., the paper is curled at the time of fixing and cannot be used, and high energy for heating is required, resulting in an increase in cost. When the electric resistance is 10 ¹² Ωcm or less, the insulating property deteriorates, and it cannot be used as a pre-wet liquid. Therefore, it is desirable that the electric resistance value be as high as possible.
When the surface tension is 21 dyne / cm or more, the wettability deteriorates, and the familiarity with the liquid developer deteriorates. Therefore, it is desirable that the surface tension be as low as possible.

In the liquid developing device for an electrostatic latent image according to the eleventh aspect, the pre-wetting liquid having silicone oil as a main component can provide the pre-wetting liquid having the characteristics according to the tenth aspect. it can.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 5, 15, 16, and 17. FIG. FIG. 1 is a schematic configuration diagram of an electrostatic latent image liquid developing device according to an 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 electrostatic latent image liquid developing device shown in FIG. 1;
4 is a view for explaining the operation of the pre-wet apparatus shown in FIG. 2, FIG. 5 is a view showing the flow of the pre-wet liquid when the pre-wet liquid supply body is brought into contact with the photoreceptor, and FIG. FIG. 16 is a schematic diagram of a developing device used in the electrostatic latent image liquid developing device shown in FIG. 1, FIG. 16 is a schematic diagram of a developing belt used in the developing device shown in FIG. 15, and FIG. It is a figure showing the method.

As shown in FIG. 1, a liquid developing apparatus for an electrostatic latent image according to an embodiment of the present invention includes a photoreceptor 10 as an image support and a pre-wet liquid for applying a pre-wet liquid on the photoreceptor 10. A wet device 20, a charging device 30 for charging the photoconductor 10, an exposure device 40 for exposing an image on the photoconductor 10,
A developing device 50 that visualizes the electrostatic latent image by supplying toner to a portion of the photoconductor 10 where the electrostatic latent image is formed;
Transfer device 6 for transferring toner on photoreceptor 10 to predetermined paper
0, and a cleaning device 70 for removing toner attached to the photoconductor 10.

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

The pre-wetting device 20 of this embodiment is similar to that of FIG.
As shown in FIG. 5, a plate-shaped pre-wet liquid supply body 202 having substantially the same length as the image width drawn on the photoreceptor 10, a case 204 for storing 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 202, Belita (registered trademark: Kanebo Corporation) is used. Belle ita is a continuous porous sponge having a three-dimensional network structure in which pores are continuous, can hold the pre-wet liquid 220 only by the volume of the pores, and is supplied with the pre-wet liquid 220 that exceeds the volume of the pores. At times, the pre-wet liquid 220 can be uniformly discharged in a direction perpendicular to the flow direction of the pre-wet liquid 220. As shown in FIG. 4, the surface of the case 204 facing the photoconductor 10 is
An opening 204a is provided so as to be able to abut against zero. The tube 210 a transports the pre-wet liquid 220 pumped by the pump 208 to the supply side 202 a of the pre-wet liquid supply 202. Note that the supply side 202a of the pre-wet liquid supply body 202 and the case 204
A space portion 204b is formed between the pre-wet liquid 220 and the pre-wet liquid 220 is supplied from the supply side 202a after being stored in the space portion 204b. The tube 210 b conveys the pre-wet liquid 220 discharged from the discharge side 202 b of the pre-wet liquid supply body 202 to the tank 206.
When an external signal is not input, the displacement device 212 holds the pre-wet liquid supply body 202 at a position away from the photoconductor 10 as shown in FIG. When the input is made, 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 is a developing belt 510, which is a developer support formed of a sheet-like member into a seamless cylindrical shape, and is provided inside the developing belt 510. A driving roller 506 for rotating and driving the developing belt 510 is brought into contact with both ends of the driving roller 506 via a developing belt 510 from a position opposite to a position where the photoreceptor 10 is disposed. The space 516 between the developing belt 510 and the driving roller 506 on the side where
And a bellows pump 502 that stores the liquid developer 508 and supplies the liquid developer 508 onto the developing belt 510 on the side where the developing belt 510 and the driving roller 506 are in contact with each other. A regulating roller 512 for adjusting the layer thickness of the liquid developer 508 supplied to the developing belt 510, and a scraping blade 51 for scraping the liquid developer 508 attached to the developing belt 510.
4 is provided.

The developing belt 510 has substantially the same length as the photoconductor 10, and is formed of a conductive and flexible sheet-like member. The developing belt 510 includes
An electrical resistance value of 10 such as a material obtained by adding metal powder to polycarbonate, nylon, fluorine resin, urethane rubber, or the like, a material obtained by conducting a process on a polyimide surface, a material having a thickness of 50 μm or less made of nickel, aluminum, stainless steel, or the like.
^A material having a conductivity of ⁶ Ωcm or less is used. Further, as shown in FIG. 15, the developing belt 510 is disposed in contact with the photoconductor 10 so as to bend in the developing space, and is rotated in a direction opposite to the rotation direction of the photoconductor 10. The liquid developer 508 supplied by the bellows pump 502 is conveyed to the surface of the photoconductor 10. As shown in FIGS. 17A and 17B, the adjustment of the pressing force when the developing belt 510 is brought into contact with the photoreceptor 10 is performed.
This was performed by replacing the contact rollers 507 provided at both ends of the central shaft 506b of No. 06 with those having different diameters.

The outer diameter of the driving roller 506 is
When the developing belt 510 is formed to be smaller than the inner diameter of the photoconductor 10 and the developing belt 510 is eccentric toward the photoconductor 10, a space 516 is formed between the developing belt 510 and the driving roller 506.
The driving roller 506 is a conductive rubber roller having a low electric resistance value so that a developing bias can be applied. At both ends of the drive roller, sprockets 506a are provided, which mesh with perforations 510a provided at both ends of the developing belt 510 to stably rotate the developing belt 510 as shown in FIG. can do.

The guide member 504 has a slippery surface on the contact surface with the developing belt 510 so that the dynamic friction coefficient between the developing belt 510 and the guide member 504 is smaller than the dynamic friction coefficient between the developing belt 510 and the driving roller 506. Good Teflon coat etc. were given.

The regulating roller 512 is disposed so as to contact the developing belt 510, and rotates in a direction opposite to the rotation direction of the developing belt 510. In our experiments,
Regarding the formation of a thin layer of the liquid developer 508 on the developing belt 510, good results were obtained when the peripheral speed of the regulating roller 512 was about twice the peripheral speed of the developing belt 510. still,
An elastic member such as a rubber roller or a sponge roller is used for the regulating roller 512.

Next, the material for forming an image used in this embodiment will be described. Liquid developer 508 used in this embodiment
The toner comprises a resin serving as a binder such as epoxy, a charge control agent for giving a predetermined charge to the toner, a coloring pigment, a toner including a dispersant for uniformly dispersing the toner, and a carrier liquid. The constitution of the toner is basically the same as that used in the conventional liquid developer, but their formulations have been changed to be compatible with silicone oil in order to adjust charging characteristics and dispersibility. The smaller the average particle size of the toner is, the better the resolution is. However, if the average particle size of the toner is small, the physical adhesive force is increased, and it is difficult to remove the toner when transferring. For this reason, in the present embodiment, the average particle diameter of the toner is adjusted so that the center comes around 2 to 4 μm for the purpose of improving the transferability.

The viscosity of the liquid developer depends on the carrier liquid used,
It is determined by the resin, the coloring pigment, the charge control agent, etc. and their concentration. In this embodiment, the viscosity is 50 to 6000 m
The experiment was performed while changing the Pa.s and the toner concentration in the range of 5 to 40%.

As the carrier liquid, a liquid having a low viscosity such as dimethylpolysiloxane oil or cyclic polydimethylsiloxane oil exhibiting high electric resistance is used. The developing belt 510
Since the liquid developer layer formed thereon is formed in a thin layer, the amount of the carrier liquid contained in the liquid developer layer is extremely small. Is very small. Therefore, the amount of the carrier liquid absorbed by the paper or the like at the time of transfer becomes extremely small. If the viscosity is 1000 mPa · s or less, almost no carrier liquid remains after fixing. According to experiments performed by the present inventors, Dow Corning DC3 having a viscosity of 2.5 mPa · s was used for the carrier liquid.
When an image output experiment was performed using No.44, no carrier liquid remained on the paper after fixing. However, because of its high volatility, the developing device needs to have a closed structure.
When an image output experiment was performed using Dow Corning's DC345 having a viscosity of 6.5 mPa · s in the carrier liquid, the image was fixed on paper after fixing in the same manner as when an image output experiment was performed using DC344. No carrier liquid was found. However, because of its high volatility, the developing device needs to have a closed structure. Furthermore, the carrier liquid has a viscosity of 2
Shin-Etsu Silicon KF-96-20 with 0 mPa · s
When an image forming experiment was carried out by using, no carrier liquid remaining on the paper after fixing was observed. Further, since the volatility is not so high, there was no need to make the developing device a closed structure. DC344, DC345 and KF-96-
20 is generally used for cosmetics and has high safety such as toxicity. There are many types of carrier liquids, such as KF9937 of Shin-Etsu Silicon Co., Ltd., and any one may be selected as long as the electric resistance, evaporation characteristics, surface tension, safety, etc. are satisfied.

In experiments conducted by the inventors, fogging and toner lumps may adhere when the surface tension is large, and experimentally, if the surface tension is 21 dyne / cm or more, a problem tends to occur in image quality. Do you get it.

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

The pre-wet liquid evaporates easily during fixing without disturbing the electrostatic latent image formed on the image support,
It is required that fogging and a lump of toner do not adhere. For example, Dow Corning DC344, USA
DC200-0.65, -1.0, -2.0, and KF96L-1 and KF9937 of Shin-Etsu Silicon Co., Ltd. Generally, it is necessary to select a highly evaporable silicone oil.

In an experiment conducted by the inventors, the liquid viscosity was 0.1.
The liquid was dried by development, transfer and fixing without any problem in the range of 5 to 3 mPa · s.
At about s, there was a tendency that time and temperature were required for drying the liquid at the time of fixing. At 10 mPa · s, the energy required for drying is too large, which is not common. Also,
If the pressure is 0.5 mPa · s or less, the volatility increases.
It is not appropriate because it is treated as dangerous goods. Further, the boiling point needs to be 250 ° C. or less due to the influence of heating the paper.

The surface tension should be 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 being stained and fogged, and improve the resolution and fogging of the image quality. Good. According to our experiments, 2
The limit is about 0 to 21 dyne / cm, and it is necessary to select one lower than this.

If the electric resistance is low, the latent image charges leak and the image is blurred. Therefore, it is necessary to use one having as high an electric resistance as possible. Experimentally 10 ¹⁴
It is desirable to be about Ωcm or more. At least 10 ¹² Ωcm is required.

Next, the operation of the electrostatic latent image liquid developing apparatus according to the present embodiment will be described. First, as shown in FIG. 3A, the above-described pre-wet liquid 220 is applied onto the photoreceptor 10 by the pre-wet device 20. When an external signal is input, the pre-wetting device 20 causes the pre-wetting liquid supply body 202 to contact the photoconductor 10. A pre-wet liquid 220 is constantly circulated inside the pre-wet liquid supply 202 by a pump 208, and the pre-wet liquid 220 exceeding the volume of the pores of the bel eater as the pre-wet liquid supply 202 is shown in FIG. As described above, while being discharged from the discharge side 202b of the pre-wet liquid supply body 202 and discharged from the bottom surface of the pre-wet liquid supply body 202,
It is uniformly applied on the photoconductor 10 without damaging the photoconductor 10.

Next, as shown in FIG. 3B, the photoreceptor 10 coated with the pre-wet liquid 220 is
To charge. The charges carried by the ions pass through the pre-wet liquid 220 layer and reach the surface of the photoreceptor surface 10. Next, an image is exposed on the charged photoconductor 10. For example, the image is exposed by a laser scanner and the photosensitive member 10 is exposed.
To form an electrostatic latent image on the surface of the substrate. As shown in FIG. 3C, the portion irradiated with the light from the laser scanner becomes conductive and loses the charge, and the portion not irradiated with the light remains as an electrostatic latent image which is an image of the charge.

Next, the developing device 50 visualizes the electrostatic latent image. Developing belt 510 by bellows pump 502
The liquid developer 508 supplied above is supplied to the regulating roller 512.
Thus, the layer thickness is adjusted, and a thin layer is formed on the developing belt 510. The liquid developer layer formed on the developing belt 510 in this way is brought close to the electrostatic latent image formed on the surface of the photoconductor 10 as shown in FIG. The toner is moved onto the photoconductor 10.

Next, as shown in FIG.
The toner image on the photoconductor 10 is transferred to a predetermined paper 604 by an electrostatic force generated by a voltage applied to the transfer roller 602 of FIG.
Transfer to Although not shown in FIG. 1, FIG.
As shown in (F), the toner transferred to the paper 604 is thermally melted by the fixing heater 704 provided in the fixing roller 702 of the fixing device and is fixed on the paper. On the other hand, the liquid developer 508 remaining on the photoconductor 10 is removed by the cleaning device 70. After the photoconductor 10 is neutralized by a neutralization device (not shown), the photoconductor 10 is repeatedly used in the above-described cycle from pre-wet to neutralization.

FIGS. 6 to 10 are views 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 the approaching process. 8, FIG. 8 is a diagram showing a state of a toner moving process, FIG. 9 is a diagram showing a process of separating a non-image portion, and FIG. 10 is a diagram showing a process of separating an image portion. Unlike the conventional developing process, the developing process of the present embodiment includes, as shown in FIG. 6, an approaching process in which the developing belt approaches the photoreceptor and the liquid developer approaches the photoreceptor surface. A toner moving process in which the toner moves by the soft contact of the pre-wet liquid layer, and a separation process in which the developing belt separates from the photoreceptor and is separated into toner adhering to the developing belt and toner adhering to the photoreceptor. It is thought that it consists of three processes.

In the approaching process, the space 516 is formed between the developing belt 510 and the driving roller 506, and as shown in FIG.
When the developing belt 510 is brought into contact with the pre-wetting liquid, the high-viscosity liquid developer composed of the carrier liquid and the toner and the pre-wetting liquid are softly contacted. As a result, the pre-wet liquid having a low viscosity is slightly pushed back and forth, and a pool of the pre-wet liquid is generated.

In the toner movement process, as shown in FIG. 8, in the image area, the toner forms a pre-wet liquid layer mainly by Coulomb force due to an electric field formed between the charge on the photosensitive member 10 and the developing belt 510. It passes and moves to the latent image plane. On the other hand, the toner in the non-image area is basically
Is separated from the liquid developer layer by the pre-wet liquid layer, so that unnecessary toner does not adhere to the surface of the photoconductor 10.

In the separation process, in the non-image part, FIG.
The liquid developer basically remains on the developing belt 510 as shown in FIG. When the two layers are separated at the interface between the pre-wet liquid layer and the liquid developer layer, 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 photoreceptor 10 displaces the pre-wet liquid layer, so that the pre-wet liquid layer is located above the toner layer and separates within the layer. On the developing belt 510, a part of the carrier liquid and a part of the pre-wetting liquid remaining after the toner moves form a layer. The pre-wet liquid remaining on the photoreceptor 10 facilitates movement of the toner due to electrostatic force in a 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 belt 510 is too thick, the liquid developer 508
Is high, the toner group moving from the developing belt 510 to the surface of the photoconductor 10 by electrostatic force forms a cluster without breaking the viscosity of the toner around the toner group. , The toner adheres excessively, and image noise occurs. In order to suppress the generation of such clusters, it is necessary to reduce the thickness of the liquid developer layer to a minimum value sufficient for development.

FIG. 12 is a view showing a state in which the developer support and the photosensitive member are brought into hard contact, and FIG. 13 is a view for explaining the soft contact of this embodiment.
As described above, in the developing process of the present embodiment, the function of the pre-wet liquid layer for image formation is important. Therefore, an important requirement in the development process is to maintain a two-layer state of a pre-wet liquid layer and a liquid developer layer. When a hard contact is made between the developer support and the photoreceptor as shown in FIG. 12, a two-layer state cannot be maintained. Therefore, in this embodiment, as shown in FIG. And a space 516 between the developing belt 510 and the driving roller 506 at least on the side where the developing belt 510 faces the photoreceptor 10 by the guide member 504.
Is formed so that the developing belt 510 is
, Causing the developing belt 510 to bend, so that a minute gap d is formed between the surface of the photoconductor 10 on which the electrostatic latent image is formed and the developing belt 510.

Next, optimization of the thickness of the toner layer, the thickness of the pre-wet liquid layer and the development gap will be described. The thickness of the toner layer needs to be reduced when the viscosity of the liquid developer is 50 to 100 mPa · s or more, particularly when the viscosity is 500 mPa · s or more. Ideally, the layer thickness is a little thicker than the layer thickness that satisfies the toner development amount required at the time of development (that is, the density when solid black is produced). This is because, when a liquid developer having a high viscosity is used, during development, the toner selected electrostatically moves onto the photoreceptor due to the extra toner due to the viscosity of the liquid. This causes image stains. In experiments conducted by the inventors, it was found that a developer having a high toner concentration was 5 μm to 40 μm having a low toner concentration.
A good image was obtained with a layer thickness of about m. When a developer having a toner concentration of 20 to 30% is used, the toner layer thickness becomes 2
Good image quality was obtained at about 0 μm.

The 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 adheres irregularly on the photoreceptor, causing image stains. As the amount of pre-wet liquid is increased, the image stain is improved,
The optimal value is confirmed. When the amount is further increased, the charge of the latent image flows, causing a decrease in sharpness and resolution, and a toner flow during development, which also tends to blur the image. D
In experiments using C344, good results were obtained with a thickness of 5 to 30 μm. With respect to a material having a lower viscosity than this, good results can be obtained with a smaller thickness or a larger thickness. However, for high viscosity ones, the optimum values tend to be narrower.

The narrower the gap between the photosensitive member 10 and the developing belt 510 is, that is, the smaller the gap between the photosensitive member 10 and the developing belt 5 is.
As in the case of the conventional developing method, it is better to form a low impedance circuit between the developing device 10 and the image forming device to improve the resolution and the uniformity of the density of the solid portion in image quality. In the high-viscosity liquid developer used in the present embodiment, the cohesive force between toners is strong, and toner released from a developer support or carrier particles by mechanical shock or electrostatic force, like powder developer, is used for development. There is no phenomenon used. That is, development is not performed if an air layer is interposed between the developer layer and the photoconductor. Therefore, it is essential that the developing belt 510 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 10. Therefore, the development gap d is equal to the developer layer,
The dimensions must be smaller than the thickness of the pre-wet liquid layer and do not disturb each layer. In this embodiment, the developing gap d is set to 2 in accordance with the difference between the viscosity of the developer and the toner concentration.
The pressure of the developing belt 510 against the photoconductor 10 is set so as to be 0 μm to 50 μm.
10, a low impedance circuit is formed.

Table 1 shows the results of an image extraction experiment performed under the above conditions. From these results, the optimum range of the viscosity of the developer and the pre-wet liquid for the developing method of this embodiment is from 100 mPa · s to 6000 mPa · s.
s, pre-wet liquid is 0.5mPa · s to 5mPa · s
s. Regarding image quality,
It changes depending on the thickness of the liquid developer layer on the developing belt, the thickness of the pre-wet liquid layer, the development gap, and the like. However, even if the various developing conditions are optimized, there is a tendency generally as shown in Table 1, It was confirmed that the optimal region of the liquid developer was within the range shown in Table 1. In addition, DC200 series manufactured by Dow Corning was used for the silicon oil of the pre-wet liquid, and DC345 manufactured by the company was used for the carrier liquid of the developer.
Was used.

[0060]

[Table 1]

According to the embodiment of the present invention, the guide member 50 is formed by using a cylindrical developing belt 510 made of a conductive and flexible sheet-like member as a developer support.
4, at least on the side where the developing belt 510 contacts the photoconductor 10,
6, the developing belt 510 is brought into contact with the photosensitive member 10 such that a space 516 is formed between the developing belt 6 and the developing belt 510, thereby causing the developing belt 510 to bend. The contact pressure when the agent layer contacts the pre-wet liquid layer formed on the photoreceptor 10 can be dispersed. Therefore, the developer layer and the pre-wet liquid layer can be brought into contact with each other while maintaining a two-layer state in the development process, and both can be separated inside the pre-wet layer at the end of the development process. This can prevent the pre-wet liquid layer from being disturbed, thereby preventing the toner from adhering to the non-image portion on the image support and disturbing the image.

Further, since the driving roller 506 for driving the rotation of the developing belt 510 is disposed inside the developing belt 510, the structure is simpler and the size can be easily reduced as compared with the conventional electrostatic latent image liquid developing apparatus. .

Further, according to this embodiment, the developing belt 5
10 are provided with perforations 510a at both ends, and perforations 510b are provided at both ends of the drive roller 506.
By providing the sprocket 506a that meshes with
The developing belt 510 can be rotated stably.

In addition, according to the present embodiment, the pressing force of the developing belt 510 against the photosensitive member 10 can be adjusted by the contact roller 507, so that the developer layer formed on the developer support can be adjusted. The contact pressure when the pre-wet liquid layer formed on the image support comes into contact can be easily optimized.

According to the present embodiment, the developing belt 51
Since a low impedance circuit is formed between the photoconductor 10 and the photoconductor 10, the movement of the toner on the developing belt 510 to the photoconductor 10 can be facilitated.

According to this embodiment, the use of silicone oil as the carrier liquid for the liquid developer has the following advantages over the conventional one.

Conventional liquid developers generally use IsoparG (registered trademark: manufactured by Exxson) as a carrier liquid.
Since the resistance value of Isopar is not as high as that of silicone oil, when the toner concentration is increased, that is, when the distance between the particles is reduced, the chargeability of the toner is deteriorated. Therefore, Isop
In the case of ar, the toner density has a limit. On the contrary,
The silicone oil used in the present embodiment has a sufficiently large resistance value, so that the toner density can be increased. Also,
Generally, in the case of Isopar, the dispersion state of the toner is good, and therefore, even if the toner concentration is 1 to 2%, the toner repels each other, so that the toner is uniformly dispersed. On the other hand, silicon oil has a toner concentration of 1-2%,
Dispersibility is not good, and precipitates soon. However, when the toner concentration is 5 to 40%, the toner is densely packed and stably dispersed. For this reason, in this embodiment, a high-viscosity liquid developer in which toner is dispersed at a 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 size of the apparatus can be reduced. Further, since the liquid developer of this embodiment is a high-viscosity liquid, storage and handling are easier than conventional low-viscosity liquid developers and powder developers.

Isopar used in the conventional liquid developer is as follows:
As mentioned above, it is highly volatile and emits a foul odor,
There was a problem of not only worsening the working environment but also causing pollution. On the other hand, the silicone oil used in this embodiment is a safe liquid and odorless, as is clear from the fact that it is used for cosmetics. The environment can be improved and no pollution problems occur.

It should be noted that the present invention is not limited to the present embodiment, and various modifications are possible within the scope of the invention. For example, in this embodiment, perforations 510a are provided at both ends of the developing belt 510, and the driving roller 5
In the above description, the sprocket 506a meshing with the perforations 510b is provided at both ends of the drive roller 06, but instead of providing the perforations and sprockets, as shown in FIG. May be used. Even in this case, the developing belt 510 can be stably rotated.

Further, in this embodiment, the bellows pump 502 has been described as a means for supplying the liquid developer 508 to the developing belt 510. However, the present invention is not limited to this. A developer supplied to the developing belt 510 by pumping a liquid developer stored in a tank using a double gear pump, or a developer supplied to the developing belt 510 by pumping a liquid developer stored in a tank using a roller. Is also good.

Further, in this embodiment, the developing belt 510
Although the case where the regulating roller 512 is used to adjust the layer thickness of the liquid developer 508 applied thereon to form a thin layer has been described, the present invention is not limited to this. For example, FIG. A regulating blade 5 made of chlorosilicone rubber, fluorine rubber, or the like as shown in a developing device 54 shown in FIG.
The thin layer may be formed by adjusting the layer thickness of the liquid developer 508 applied on the developing belt 510 by using the layer 42. In the experiments performed by the present inventors, the contacting method between the regulating blade 542 and the developing belt 512 is designed such that the regulating blade 542 contacts the trailing direction and the tip of the regulating blade 542 is lifted from the contact surface between the regulating blade 542 and the developing belt 510. By doing so, it was possible to form a stable developer thin layer. The regulating blade 542 used had a rubber hardness of 70 degrees.

In this embodiment, the pre-wet liquid 220 is used as the pre-wet
02, the present invention is not limited to this, and the pre-wet apparatus supplies the pre-wet liquid to the pre-wet liquid supply only during pre-wet. Is also good.

FIG. 14 is a view showing a modification of the pre-wetting device used in the liquid developing device for an electrostatic latent image in this embodiment. The pre-wet device 80 shown in FIG. 14 stores a plate-shaped pre-wet liquid supply 802 having a length substantially equal to the image width drawn on the photoconductor 10 and a supply side 802a of the pre-wet liquid supply 802. Case 804,
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;
And a displacement device (not shown).

The tube 810 conveys the pre-wet liquid 220 pumped by the pump 808 to the supply side 802 a of the pre-wet liquid supply 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
After 0 is stored in this space, it is supplied from the supply side 802a. When no external signal is input, the displacement device holds the pre-wet liquid supply body 802 at a position away from the photoconductor 10 as shown in FIG.
When a signal from the outside is input, as shown in FIG.
Contact. When a signal from the outside is input, the pre-wet device 80 starts the pre-wet liquid 2 by the pump 208.
20 is supplied to the pre-wet liquid supply unit 802 and the discharge side 80 of the pre-wet liquid supply unit 802 is
2b is brought into contact with the photoconductor 10. Beruita which is a pre-wet liquid supply body 802 (registered trademark: Kanebo Corporation)
The pre-wet liquid 220 that exceeds the volume of the pores is discharged from the discharge side 802b of the pre-wet liquid supply body 802,
It is applied on the photoconductor 10. Thereby, the pre-wet liquid can be applied with a uniform thickness without damaging the surface of the photoreceptor.

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

Further, in the present embodiment, a description has been given of a case in which a continuous porous sponge Berita (trade name: Kanebo Co., Ltd.) is used as the pre-wet liquid supply body, but the present invention is not limited to this. Instead, as long as a predetermined amount of the pre-wet liquid can be applied to the surface of the photoreceptor, a sponge other than the continuous porous sponge, for example, a rubber roller may be used. Further, the shape is not limited to a plate shape, and may be, for example, a roll shape.

Further, in this embodiment, the case where an organic photoreceptor is used as the image support has been described. However, the present invention is not limited to this, and the image support may be any of various photoreceptors used in the Carlson method. Alternatively, an electrostatic recording paper such as an electrostatic plotter may be used in which an insulator layer is formed on a conductor for directly forming an electrostatic latent image such as ionography.

The present invention is not limited to this embodiment. If the pre-wet liquid layer is formed and the layer thickness of the developer is 5 to 40 μm, the viscosity of the high-viscosity developer becomes 1
It may be 0000 mPa · s. Currently, 600
It is considered that a high-viscosity developer of 0 mPa · s or more makes it difficult to stir the carrier liquid and the toner.
It may be 0 mPa · s or more. The viscosity is 10,000 mPa.
Anything beyond s becomes impractical.

[0079]

As described above, according to the first aspect of the present invention, with the above-described structure, the developer layer formed on the developer support and the pre-form formed on the image support are formed. Since the contact pressure at the time of contact with the wet liquid layer can be dispersed, the developer layer and the pre-wet liquid layer can be contacted while maintaining a two-layer state in the development process, and the development process is completed. Sometimes, the two are separated inside the pre-wet liquid layer, so that the pre-wet liquid layer can be prevented from being disturbed, and therefore, it is possible to prevent the toner from adhering to the non-image portion on the image support and disturb the image. By using a high-viscosity liquid developer in which toner is dispersed at a high concentration, a high-resolution, easily miniaturized, and low-pollution electrostatic latent image liquid can be used. Provide developing device It is possible.

According to the second aspect of the present invention, as described above, perforations are provided at both ends of the developer support, and sprockets meshing with the perforations are provided at both ends of the drive roller. In addition to the effects of the invention described in Item 1, it is possible to provide a liquid developing device for an electrostatic latent image that can rotate the developer support stably.

According to the third aspect of the present invention, as described above, since the grooves or projections in a lattice pattern are formed on the surface of the drive roller, the electrostatic effect having the same effect as the second aspect of the present invention is obtained. A latent image liquid developing device can be provided.

As described above, according to the fourth aspect of the present invention, the application roller is provided on both sides of the drive roller and in contact with the image support, and the outer diameter of the application roller is changed to thereby achieve the development. By providing a pressure adjusting mechanism for adjusting the pressing force of the developer support to the image support, the developer layer formed on the developer support and the pre-wet liquid layer formed on the image support A liquid developing device for an electrostatic latent image can be provided which can easily adjust the contact pressure at the time of contact.

According to the fifth aspect of the present invention, as described above, a low impedance circuit is formed between the developer support and the image support, so that the toner image on the developer support is formed. It is possible to provide a liquid developing device for an electrostatic latent image that can be easily moved to a support holder.

According to the sixth aspect of the present invention, as described above, with the above configuration, it is possible to provide a liquid developing device for an electrostatic latent image having the same effect as the first aspect of the present invention. Can be.

As described above, according to the seventh aspect of the present invention, by adopting the above configuration, in addition to the effect of the first aspect of the present invention, the liquid developer and the pre-wet liquid are well adapted. A liquid developing device for an electrostatic latent image can be provided.

As described above, according to the eighth aspect of the present invention, by adopting the above-described structure, in addition to the effect of the sixth aspect of the invention, it is possible to reduce pollution and improve the working environment. It is possible to provide a liquid developing device for an electrostatic latent image that can be formed.

According to the ninth aspect of the present invention, as described above, in addition to the above-described effects, the electrostatic latent image liquid developing apparatus that can easily peel off the toner during transfer is provided. Can be provided.

As described above, according to the tenth aspect of the present invention, by adopting the above-described configuration, in addition to the above-described effects, the electrostatic latent image capable of improving the releasability at the time of transfer is provided. Can be provided.

As described above, according to the eleventh aspect of the present invention, in addition to the above-mentioned effects, in addition to the above-described effects, the electrostatic latent can further reduce pollution and improve the working environment. An image liquid developing device can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a liquid developing device for an electrostatic latent image according to an 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 view for explaining the operation of the electrostatic latent image liquid developing device shown in FIG. 1;

FIG. 4 is a view for explaining the operation of the pre-wet apparatus shown in FIG. 2;

FIG. 5 is a diagram illustrating a flow of a pre-wet liquid when a pre-wet liquid supply body is brought into contact with a photoconductor.

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

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

FIG. 8 is a diagram illustrating a state of a toner moving process.

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

FIG. 10 is a diagram showing a separation process of an image part.

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

FIG. 12 is a diagram illustrating a state in which a developing roller and a photoconductor are brought into hard contact with each other.

FIG. 13 is a view for explaining soft contact of the electrostatic latent image liquid developing device according to the present embodiment.

FIG. 14 is a diagram illustrating a modified example of the pre-wet device used in the electrostatic latent image liquid developing device of the present embodiment.

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

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

FIG. 17 is a diagram illustrating a method of abutting a photosensitive member and a developing belt of a liquid developing device for an electrostatic latent image according to the present exemplary embodiment.

18 is a diagram illustrating a surface shape of a modified example of the drive roller used in the developing device illustrated in FIG.

FIG. 19 is a view showing a modification of the developing device used in the electrostatic latent image liquid developing device shown in FIG. 1;

[Explanation of symbols]

 Reference Signs List 10 photoreceptor 20, 80 pre-wet device 30 charging device 40 exposure device 50, 54 developing device 60 transfer device 70 cleaning device 202, 802 pre-wet liquid supply 204, 804 case 206, 806 tank 208, 808 pump 210a, 210b, 810 Tube 212 Displacement device 220 Pre-wet liquid 302 Corona discharger 502 Bellows pump 504 Guide member 506 Drive roller 506a Sprocket 506b Center shaft 507 Applied roller 508 Liquid developer 510 Development belt 510a Perforation 512 Regulation roller 514 Scraping blade 516 Space 542 regulating blade 602 transfer roller 604 paper 702 fixing roller 704 fixing heater

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tsutomu Sasaki 2-6-3 Otemachi, Chiyoda-ku, Tokyo Nippon Steel Corporation (56) References JP-A-51-36953 (JP, A) Kaihei 6-75469 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 15/10

Claims (11)

(57) [Claims] 1. An electrostatic latent image formed on an image support,
What is claimed is: 1. A liquid developing device for an electrostatic latent image which is developed with toner as charged visualized particles, wherein said pre-wet liquid is a chemically inert dielectric liquid having releasability on said image support. A pre-wet means for applying a developer, a substantially cylindrical developer support formed of a conductive and flexible thin plate-like member, and the developer support provided inside the developer support. A driving roller that is driven to rotate;
A guide member that contacts the image support by bending the developer support by contacting both ends of the drive roller via the developer support, and insulates the developer support on the developer support. A high-viscosity liquid developer in which a toner is dispersed at a high concentration in a ionic liquid is applied, and the developer support is bent to contact the image support to contact the latent image surface of the image support. And a developing means for supplying a high-viscosity liquid developer. 2. A liquid developing device for an electrostatic latent image according to claim 1, wherein perforations are provided at both ends of said developer support, and sprockets meshing with said perforations are provided at both ends of said driving roller. apparatus. 3. A liquid developing device for an electrostatic latent image according to claim 1, wherein grooves or projections in a lattice pattern are formed on the surface of said drive roller. 4. An adhering roller for contacting the image support on both sides of the drive roller, and by changing the outer diameter of the adhering roller, the pressing force of the developer support on the image support is reduced. 4. A liquid developing device for an electrostatic latent image according to claim 1, further comprising a pressure adjusting mechanism for adjusting. 5. A liquid developing device for an electrostatic latent image according to claim 1, wherein a low impedance circuit is formed between said developer support and said image support. apparatus. 6. The high-viscosity liquid developer having a viscosity of 100 to 10000 mPa · s is used, and the thickness of the high-viscosity liquid developer supplied to the surface of the developer support is regulated to 5 to 40 μm. 6. The electrostatic latent image liquid developing device according to claim 1, wherein the electrostatic latent image is formed. 7. The liquid developer according to claim 1, wherein the viscosity of the insulating liquid is 0.5 to 1000 mPa · s, and the electric resistance is 10 ¹² Ωcm.
As described above, the surface tension is 21 dyne / cm or less, and the boiling point is 10
The liquid developing device for an electrostatic latent image according to claim 6, wherein the temperature is 0 ° C or more. 8. The liquid developing device for an electrostatic latent image according to claim 7, wherein said liquid developer uses silicon oil as an insulating liquid. 9. The liquid developer has an average particle diameter of 0.1 to 5
9. The electrostatic latent image liquid developing apparatus according to claim 6, wherein the liquid developer contains a toner of μm in a concentration of 5 to 40%. 10. The pre-wet liquid has a viscosity of 0.5.
The electrostatic latent image according to claim 6, wherein the electrostatic latent image has an electric resistance of 10 ¹² Ωcm or more, a boiling point of 100 to 250 ° C, and a surface tension of 21 dyne / cm or less. Liquid developing device. 11. The pre-wetting liquid according to claim 1, wherein the pre-wetting liquid contains silicone oil as a main component.
0. A liquid developing device for an electrostatic latent image according to 0.