JP2000010413A - Liquid development device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid development device capable of using a developer of high concentration by which the vapor of a carrier liquid of the developer is hardly diffused in the air and a developer circulating device for controlling the concentration of the developer is not necessary. SOLUTION: Nonvolatile concentration of a developer is from 10% wt. to 30% wt. and this device is provided with a drawing roller drawing up the developer, a developing roller 11 whose the surface roughness on which the developer is supplied from the drawing roller is from 8 μmRz to 25 μmRz and a film thickness control member abutting on the roller 11 and controlling the film thickness of the developer on the roller 11. The roller 11 is energized to a recording medium, the rotating direction of the roller 11 rotates in the direction opposite to the carrying direction of the recording medium and an electrostatic latent image on the recording medium is developed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used for a recording device for performing recording by performing density gradation on a pixel basis.
The present invention relates to obtaining a high-quality image by performing faithful development with fine particle toner using a liquid developer for developing an electrostatic latent image including a halftone.

[0002]

2. Description of the Related Art A conventional wet developing apparatus is disclosed in
Japanese Patent No. 334007 discloses a developing device main body formed in a liquid-tight housing shape having an upper end opened using a developer having a toner concentration of 5% to 70%, and a developing device housed inside the developing device main body. And a developing roll partially immersed in the developing solution in the developing device main body, facing the surface of the photosensitive drum, and rotationally driven in a direction opposite to the rotating direction of the photosensitive drum. ing.

Japanese Patent Application Laid-Open No. 9-185264 discloses a developer container containing a liquid developer in which charged toner particles comprising at least a colorant and a resin are dispersed in an electrically insulating liquid. A supply roller for uniformly adhering the liquid developer from the developer container to the surface of the developing roller, and a liquid toner layer in which charged toner particles are aggregated by applying an electric field to the liquid developer adhering to the surface of the developing roller. And an electric field applying unit for forming the developing roller holding the liquid toner layer in a state where the charged toner particles are aggregated, and developing the developing roller on the belt photoconductor on which the electrostatic latent image is formed. ing.

[0004]

Problems to be Solved by the Invention Japanese Patent Laid-Open No. 7-33400
In the image recording apparatus disclosed in Japanese Patent Application Laid-Open No. 7-107, the distance between the photosensitive drum, which is the electrostatic latent image carrier and the developing roller, is increased as the density of the toner is increased, in order to prevent the background from being soiled by toner other than the image portion. There is a problem that it is necessary to manage well, it is difficult to secure the accuracy and the cost is increased.

Further, in the case of Japanese Patent Application Laid-Open No. Hei 9-185264, in order to prevent the toner on the developing roller from rubbing against the belt photosensitive member at the contact portion between the belt photoreceptor and the developing roller, dirt is prevented. In addition, it is necessary to control the moving speed of the belt photoreceptor and the rotating speed of the developing roller to be equal, and it is difficult to secure the accuracy, and the cost is increased.

An object of the present invention is to solve such problems and to provide a small and high-definition liquid developing apparatus.

[0007]

In order to achieve the above object, a pre-recording medium formed by means for forming an electrostatic latent image corresponding to an image signal on a recording medium and means for guiding and conveying the recording medium In a liquid developing apparatus for developing the above electrostatic latent image with a developer in which toner particles are dispersed, a nonvolatile concentration of the developer is from 10% wt to 30% wt, and a predetermined amount of the developer is used. A developer holding portion to be held, a pumping roller that is immersed in the developer in the developer holding portion, and draws up the developer by rotating, and abuts on the pumping roller, and the developer on the pumping roller is supplied. 8μm surface roughness
A developing roller having a thickness of 25 μm Rz from Rz, and a film thickness control member that abuts on the developing roller and controls a film thickness of a developer on the developing roller, and urges the developing roller against the recording medium; At a contact position between the developing roller and the recording medium, the developing roller rotates in a direction in which a moving direction of the developing roller is opposite to a conveying direction of the recording medium, and the developer on the developing roller causes the pre-recording medium to rotate. The upper electrostatic latent image is developed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic structural view of a developing section of a liquid developing apparatus according to one embodiment of the present invention.

The developer holding section 85 holds a predetermined amount of the developer 16 in which charged toner particles are dispersed.

The pumping roller 101 is immersed in the developer 16 in the developer holding section 85, and rotates during development,
The developer is held in a film shape on the periphery.

The developing roller 11 includes a pumping roller 101
To the pump roller 1 with a predetermined pressing force.
The developer on the circumference of No. 01 is transferred, and the developer is held in a film shape on the circumference.

The developing blade 12 is pressed against the developing roller 11 with a predetermined pressing force, and regulates the thickness of the developer on the periphery of the developing roller 11.

In this embodiment, the surface of the developing roller 11 is
Fine irregularities are formed so as to have a predetermined surface roughness by the surface treatment so that the developer can be sufficiently supplied.
The adjustment of the gap between the developing roller 11 and the developing blade 12 is not shown, but can be defined by providing a mechanism for adjusting the support of the developing blade 12 manually or automatically.

The amount of developer supplied to the pumping roller 101 depends on the amount of the developing roller 1 after passing through the developing blade 12.
It is necessary to supply more than the amount of the developer supplied on one circumference. Therefore, the pressing force between the drawing roller 101 and the developing roller 11, the surface roughness of the drawing roller 101, the peripheral speed difference between the drawing roller 101 and the developing roller 11, and the material of each roller may be selected so as to satisfy this condition.
When the developer whose density has changed after development remains on the developing roller, the efficiency of replacement with the developer supplied to the developing roller by the pumping roller 101 is less than 100%. Considering this, it is necessary to increase the developer supply amount of the pumping roller 101. However, the replacement efficiency can be improved by scraping off the residual developer on the developing roller 11 after development by a scraping blade (not shown).

The recording medium 1 is formed on its surface with an electrostatic latent image corresponding to image data to be recorded by an electrostatic latent image forming means (composed of the recording head 5 and the back electrode 28 shown in FIG. 3). Things.

The developing back electrode 29 is pressed with a predetermined pressing force corresponding to the developing area in the longitudinal direction of the developing roller 11, and is formed of an elastic member so that the contact with the developing roller 11 is stabilized. .

The recording medium 1 is transported by guide means 4 for guiding and transporting.
(See FIG. 3), the developing roller 11 and the developing rear electrode 2
9 is inserted.

At the time of development, the developing roller 11
Is held around the circumference, and the charged toner particles in the developer 12 adhere to the recording medium 1 corresponding to the electrostatic latent image on the recording medium 1 to form a developed image 33.

At this time, the developing roller 11 and the developing back electrode 2
During the period 9, a bias is applied by the developing bias power supply 30 so that the charged toner particles in the developer 16 move toward the developing roller 11, so that the toner particles do not adhere to the non-image area and no fog occurs. Like that.

That is, in the non-image area, the toner particles do not adhere due to the developing bias, but the solvent 32 in the developer adheres due to the surface tension with the recording medium 1. Here, the solvent 32 adhered to the non-image area is vaporized thereafter, leaving no state.

Here, the developing bias can be changed according to the image, and the configuration of the developing bias section of the present embodiment does not limit the present invention.

In the present embodiment, a transport path is formed so that the recording medium 1 is wound around the developing roller 11 at a predetermined winding angle before and after the developing section where the developing roller 11 and the developing back electrode 29 are in contact. The paper guides 40a and 40b are arranged as described above.

When the recording medium 1 is wound around the developing roller 11 at a predetermined angle, the developing area is enlarged. As a result, the developing speed is improved, the margin for the change in the contact state in the developing section is widened, and uneven development can be reduced.

By connecting and integrating the paper guides 40a and 40b, the number of parts of the apparatus can be reduced and the conveyance path of the recording medium 1 can be simplified.
The conveyance of the recording medium 1 can be further stabilized.

In this embodiment, a conductive layer is formed on the side of the recording medium 1 opposite to the side on which the latent image is formed, that is, on the side in contact with the paper guide. By applying a developing bias from a developing bias power supply 30 between the paper guide in which the paper guides 40a and 40b are integrated and the developing roller 11, fogging is prevented even in a configuration in which the developing back electrode 29 of the developing unit is not pressed. can do.

Next, the relationship between the surface roughness of the developing roller and the printing condition will be described with reference to FIGS. In the present embodiment, as described above, the surface of the developing roller 11 has fine irregularities formed by surface treatment.

As described above, when a thin film of the developer 16 is formed on the developing roller 11, the developing blade 12 pressed against the developing roller 11 with a predetermined pressing force and the unevenness of the surface of the developing roller 11 cause The flow of the developer is regulated to control the thickness of the developer. Further, when performing development, a gap between the recording medium 1 pressed against the developing roller 11 with a predetermined pressing force by the development back electrode 29 is formed.
It can be ensured by unevenness on the surface of the developing roller 11.

When the surface roughness of the developing roller 11 is small,
As shown in FIG. 2, the developer thin film formed on the developing roller 11 becomes thinner, and supplies a developer necessary to obtain a sufficient density (for example, a reflection density of 1.3 or more). Things become difficult. On the other hand, when the surface roughness difference of the developing roller 11 is large, the film thickness of the developer thin film formed on the developing roller 11 becomes large, so that fogging due to toner adhesion in a non-image portion is easily caused. To prevent this,
The necessary developing bias, that is, the voltage of the developing bias power supply 30 applied between the developing roller 11 and the developing back electrode 29 increases, and the width of the latent image potential that can be effectively used for image formation decreases. Therefore, there is an appropriate value for the surface roughness of the developing roller 11. Furthermore, in the case of the same surface roughness, the damage to the recording medium 1 is less when the tip shape of the unevenness is smooth than when the tip shape is sharp, and a better image can be obtained.

Table 1 shows the relationship between the surface roughness and the printing condition obtained by the inventors through experiments.

[0031]

[Table 1]

As the developing roller, a SUS304 roller having a diameter of 20 mm was used, and the surface was subjected to sand blasting with glass beads, and the surface roughness was controlled according to the processing conditions. As a result, it was confirmed that by setting the surface roughness to 8 to 25 μm Rz, there was no fog in the non-image portion and there was an area where the image density could be secured.

Here, the surface roughness of the developing roller was measured using a stylus type surface roughness measuring instrument SV-9524 (manufactured by Mitutoyo) with a reference length of 0.8.
After measuring the roughness curve of mm, the surface roughness was calculated according to the definition of the ten-point average roughness Rz of JIS B 0601-1994, and evaluated by the average value of any three points on the developing roller 11.

The thickness of the developer thin film formed on the surface of the developing roller having a surface roughness capable of ensuring image density without fogging in the non-image area was 5 to 20 μm.

The recording medium 1 of this embodiment has a surface roughness of 10
300 seconds (the surface roughness of paper or the like is measured according to JISP 8119). It is clear that if the surface roughness of the recording medium 1 is higher than this, unevenness occurs in the image portion and the non-image portion.

If the developing roller 11 is made of a material into which the developer penetrates into the inside of the roller from the surface, for example, a sponge or the like which is a porous elastic member, the material constituting the roller deteriorates due to the developer penetrating into the inside of the roller. The properties of the developing roller may be impaired due to the solidification of the developing solution that has permeated into the developing roller. Therefore, it is desirable to use a material that does not allow the developer to permeate from the surface of the roller to the inside. Although stainless steel is shown in this embodiment, the developing roller can be made of aluminum, hard plastic, or the like.

FIG. 4 shows the relationship between the contact pressing force and the fog density on a developing roller having a surface roughness of 10 μm.

It can be seen that by setting the force with which the developing roller is pressed against the recording paper at 200 mg / mm or less, development without fogging in the non-image area can be performed.

FIG. 3 shows an example of a schematic configuration of the liquid developing apparatus of the present invention. The recording paper 1 is put into the hopper 2 and a recording start command is waited. In response to a recording start command output from the recording device control unit 23, the paper feed roller 3 rotates to start separation and feeding of the recording paper 1. Then, the recording paper 1 is conveyed with high precision by a paper feed roller 4 that holds only both ends. The recording head 5 installed on the upstream side of the paper feed roller 4 in the recording paper conveyance direction and facing the back electrode 28 with the recording paper interposed therebetween has the recording paper 1 sandwiched by the paper feed roller 4 and is shown in the drawing. When the recording start position is reached, recording of the first color electrostatic latent image is started.

For example, the recording start position is immediately after the leading edge of the recording paper 1 is nipped by the paper feed roller 4. This positioning can be performed based on the amount of paper fed from an optical reflective sensor (not shown) or by providing an optical reflective sensor near the recording head 5. The recording head 5 is an ion flow head as described later.

Until the recording paper 1 is nipped by the paper feed roller 4, the recording head 5 or the back electrode 28 is retracted away from the recording paper 1, so that the recording paper 1 is hardly affected by dirt. are doing. Further, at the time of recording the electrostatic latent image, the recording head 5 or the back electrode 28 is moved between the recording head 5 and the back electrode 2 by a gap holding mechanism (not shown).
The gap 8 is moved until a predetermined value is reached, and the gap between the recording head 5 and the recording paper 1 is defined.

When the recording paper 1 is nipped by the paper feed roller 4, the recording paper 1 is released from the paper feed roller 3.
The transport load may be reduced.

When the recording head 5 starts recording an electrostatic latent image on the recording paper 1, for example, when recording from yellow,
The developing unit housing 21 is rotated and stopped to a position where the yellow developing roller 52 faces the developing back electrode 29, that is, a developing position, and yellow developing is started. Alternatively, the developing rear electrode 29 disposed at the developing position is moved to define the gap between the developing roller and the recording paper 1 and yellow development is started. In the present embodiment, the gap between the developing roller and the recording paper 1 at the time of development is brought into contact with a light force, and it is not necessary to adjust the gap in the developing section.
The developing back electrode 29 is made of a soft elastic member, so that the influence of the change in the pressing force due to the error of the moving amount of the developing back electrode 29 is reduced.

When the recording paper 1 on which the electrostatic latent image has been formed by the recording head 5 is conveyed to the developing section, the developing unit housing 21 is rotated by 45 degrees in the drawing, or the developing back electrode 29 is turned on. By retracting in the middle right direction, the recording paper 1
Are not in contact with the development back electrode 29 or the development roller 52. As a result, it is possible to prevent recording paper conveyance failure due to buckling of the recording paper 1 that occurs when the recording paper 1 is inserted into the contact position between the developing back electrode 29 and the developing roller.

As shown in the figure, the developing unit housing 21 can perform magenta (M) development, cyan (C) development, and black (K) development in addition to yellow (Y) development. Each developing roller and the like are provided. In the following description, each color is represented by Y, M, C, and K.

In the present invention, the developing back electrode 29 is a conductive member, and applies an electric field in the direction in which the toner in the developing section moves in the direction of the developing roller 52 to prevent fogging of the toner on the non-image area. are doing. In addition, the amount of the carrier liquid remaining on the recording paper after the development is reduced by setting the rotation direction of the developing roller to be opposite to the conveying direction of the recording paper 1.
This reduces the scattering of the carrier liquid into the atmosphere and realizes a simple configuration that does not require a squeeze roller.

As the recording paper 1 is transported, formation of a latent image on the recording paper 1 and development thereof are performed. The recording paper 1 is further conveyed, and is heated and dried by, for example, a sheet heater 8 as a heating unit, so that the toner image on the recording paper 1 is fixed.

Thereafter, the developing unit housing 21 is rotated to separate the Y developing roller from the developing section, and the guide roller 7 provided after the recording paper 1 has passed through the sheet heater 8 and the paper feed roller 4 are rotated in the reverse direction. The recording paper 1 is conveyed to a position where formation of a second-color electrostatic latent image is started. At this time, the developing roller for the second color, for example, M, is positioned in the developing section.

The recording paper 1 corresponding to the image signal of the second color
For example, recording of an M electrostatic latent image on the Y image is started in the same manner as in the first color. Further, magenta development is performed in the same manner as the first color Y development. Thereafter, recording of the third and fourth colors is performed in the same manner, and a full-color image is formed.

Here, the recording head 5 for forming an electrostatic latent image on the recording paper 1 controls the amount of passage of ions generated from an ion source (not shown) to control the electrostatic latent image according to image information. This is an ion flow head that forms an image on a recording medium. This head may be a multi-stylus head that selectively applies a voltage to a large number of needle electrodes to form an electrostatic latent image on a recording medium. If the recording medium is made of a photoreceptor, the recording head 5 can use a laser generator used in a conventional laser beam printer, an LED printer, or the like.
An ED array can be used.

FIG. 5 is a schematic structural view of a developing section of a liquid developing apparatus according to another embodiment of the present invention.

The developer holding section 85 holds a predetermined amount of the developer 16 in which the charged toner particles are dispersed.

The cylindrical developing belt 19 is driven to rotate by belt driving rollers 102a and 102b in contact with each other. One end of the developing belt 19 is immersed in the developer 16 in the developer holding portion 85 together with the driving roller 102b, and rotates during development to hold the developer in a film shape on the periphery.

The developing blade 12 includes a driving roller 102a.
Is pressed against the developing belt 19 with a predetermined pressing force, and regulates the film thickness of the developer on the periphery of the developing belt 19.

In the present embodiment, fine irregularities are formed on the surface of the developing belt 19 by surface treatment so as to have a predetermined surface roughness, and the gap with the developing blade 12 is defined by a simple system. be able to. Further, the belt driving roller 102a is moved so that the developing belt 19 becomes slack.
And 102b are arranged so that the slack side of the developing belt 19 contacts the recording medium 1.

In this embodiment, since the conveyance path of the recording medium is formed substantially linearly and the development area can be widened, the development speed can be improved while ensuring the reliability of paper conveyance. In addition, it is possible to widen a margin for a change in the contact state in the developing unit and reduce unevenness in development.

As described in the previous embodiment, the replacement efficiency can be improved by bringing the scraping blade into contact with the developing roller 11 after development to scrape off the residual developer on the developing roller.

FIG. 6 is a schematic structural view of a developing section of a liquid developing apparatus according to a further embodiment of the present invention.

This embodiment is different from the embodiment shown in FIG.
The belt driving roller 102c is added so as to be inscribed in the developing belt 19. With this configuration, the development region can be formed more stably.

The contact between the recording medium 1 and the developing belt 19 can be further stabilized by forming the developing back electrode 29 by a roller and pressing it between the belt driving rollers 102a and 102c with a predetermined pressing force.

In the case where ordinary recording paper 1 which is not a dedicated recording paper is used, as shown in FIG. 7, the recording head 5 temporarily supports the image data on the dielectric belt 25 on which an electrostatic latent image can be formed. An electrostatic latent image is formed and developed with each color developing roller. By performing this process four times, for example, a color image is formed on the dielectric belt 25. afterwards,
The recording paper 1 is separated and conveyed by the paper feed roller 3, and the color image is transferred by the transfer roller 24 having a built-in heating unit.

Here, the selection of the developing device is performed by the developing device swing cam 107 moving the developing device 100 in the right-hand direction in the figure to press the developing rollers of each color against the dielectric belt 25 with a predetermined pressing force. The pressing force for pressing the dielectric belt 25 of the developing roller is equal to the plurality of belt guide rollers 3.
4 is defined by the tension of the dielectric belt 25 caused by the pressing force with a predetermined pressing force against the dielectric belt 25. The conveying force of the dielectric belt 25 is given by the frictional force of the belt guide roller 34.

Transfer roller 24 heated immediately before transfer
Presses the dielectric drum 25 at the first timing when the recording paper 1 is interposed between the dielectric drum 25 and the transfer roller 24. When the recording paper 1 is heated and pressed against the image surface, the image is transferred to the recording paper 1.

The transferred recording paper 1 is discharged out of the apparatus.

Ink remaining on the dielectric belt 25 without being transferred to the recording paper 1 is removed by the belt cleaner 3.
5 to prevent disturbing the next color image. Further, a uniform charger 36 is provided on the downstream side of the belt cleaner 35 to which AC is applied to generate positive and negative bipolar ions, thereby eliminating the influence of the previous color electrostatic latent image. Here, by applying a bias to the voltage applied to the uniform charging device 36 so that the dielectric belt 25 is charged to the same polarity as the charging polarity of the toner particles after passing through the uniform charging device 36, the fogging of the non-image portion is performed. Can be prevented.

Here, a system in which four-color images are superposedly formed on the dielectric belt 25 and then transferred to the recording paper 1 has been described. However, the recording paper 1 is reciprocated four times to form a latent image for each color. A full-color image can be similarly formed on the recording paper 1 by performing development, transfer, and cleaning. However, in this case, it is necessary to pay attention to the paper feeding accuracy of the recording paper transport system in order to maintain the color registration accuracy on the recording paper 1.

In this embodiment, the configuration using the dielectric belt has been described, but the configuration in which the electrostatic latent image is formed on the dielectric drum can be similarly realized.

FIG. 8 is a schematic structural view of a liquid developing apparatus according to another embodiment of the present invention.

In the present embodiment, the toner image formed on the dielectric belt 25 is transferred onto the transfer drum 37. It is to be transferred. In this method, a transfer drum 37 and a drum cleaner 38 for cleaning the transfer drum 37 are newly required. However, in order to clean the dielectric belt 25 for each color, mixing of the previous color to the developing device is performed. It is suitable for obtaining a high-quality image without disturbing food or a previously developed toner image. In addition, 4
Since the full-color image of the color is transferred onto the recording paper 1 at a time, the colors can be superimposed on the recording paper 1 with high accuracy.

[0070]

According to the present invention, a high-concentration developer in which the vapor of the carrier liquid of the developer is hardly scattered into the atmosphere and a circulation device for the developer for controlling the concentration of the developer is unnecessary. The liquid developing device which can be used can be constituted by a simple system.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a developing unit of a liquid developing device according to an embodiment of the present invention.

FIG. 2 shows a relationship between a developing roller surface roughness and an ink film thickness on the developing roller.

FIG. 3 is a schematic configuration diagram of a liquid developing device of the present invention.

FIG. 4 shows a relationship between a developing roller contact pressing force and a fog density.

FIG. 5 is a schematic configuration diagram of a developing unit of a liquid developing device according to another embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of a developing unit of a liquid developing apparatus according to another embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of a liquid developing device according to an embodiment of the present invention.

FIG. 8 is a schematic configuration diagram of a liquid developing device according to an embodiment of the present invention.

[Explanation of Signs] 1 ... recording paper, 2 ... cartridge, 3 ... paper feed roller, 4 ...
Paper feed roller, 5 ... recording head, 6 ... paper guide, 7 ...
Guide roller, 8: sheet heater, 9: paper feed roller A,
Reference Signs List 10: buffer guide, 11: developing roller, 12: developing blade, 13: blade fixing plate, 14: scraping blade, 15: cover, 16: developer, 17: developer cartridge, 18: cleaner, 19: developing belt , 20
... Rotating shaft, 21 ... Developing unit housing, 22 ... Housing, 23
... Recording device controller, 24 ... Transfer roller, 25 ... Dielectric belt, 26 ... Guide roller, 27 ... Emery roller, 28
... Back electrode, 29 ... Development back electrode, 30 ... Development bias power supply, 31 ... Ground, 32 ... Developer carrier liquid, 33 ... Developed image, 34 ... Belt guide roller, 35 ... Belt cleaner, 36 ... Charger, 37 ... Transfer drum, 38: drum cleaner, 40: paper guide.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Junichi Matsuno 502, Kachimachi, Tsuchiura-shi, Ibaraki Pref. Machinery Research Laboratories, Hitachi, Ltd. Hitachi, Ltd.Electrical Equipment Division (72) Inventor Mitsuzu Suzuki 1-1-1, Higashitagacho, Hitachi City, Ibaraki Prefecture F-Term, Hitachi Electric Corporation Electric Equipment Division 2H074 AA03 AA07 BB31 BB61

Claims (6)

[Claims] 1. A means for forming an electrostatic latent image corresponding to an image signal on a recording medium, a means for guiding and conveying the recording medium, and a developer in which toner particles are dispersed in the electrostatic latent image on the preceding recording medium A liquid developing device having a developer concentration of 10% wt to 30% wt; a developer holding unit for holding a predetermined amount of the developer; A drawing roller immersed in a developer and pumping up the developer; and a developing roller having a surface roughness of 8 μmRz to 25 μmRz in contact with the drawing roller and supplying the developer on the drawing roller, and the developing roller. A liquid developing device for developing an electrostatic latent image on a pre-recording medium with the above developer. 2. A means for forming an electrostatic latent image corresponding to an image signal on a recording medium, means for guiding and conveying the recording medium, and a developer in which toner particles are dispersed in the electrostatic latent image on the preceding recording medium A non-volatile concentration of the developer from 10% wt to 30% wt; a developer holding unit for holding a predetermined amount of the developer; and a developer immersed in the developer in the developer holding unit. A pumping roller for pumping up the developer, a developing roller in contact with the pumping roller, and having a surface roughness of 8 μmRz to 25 μmRz to which the developer on the pumping roller is supplied; and a developing roller in contact with the developing roller. A film thickness control member for controlling the film thickness of the developer on the roller, biasing the developing roller against the recording medium, and moving the developing roller at a contact position between the developing roller and the recording medium. Is the recording medium A liquid developing device that rotates in a direction opposite to the conveying direction of the developing roller and develops the electrostatic latent image on the previous recording medium with the developer on the developing roller. 3. The liquid developing device according to claim 1, wherein a conductive member is provided at a position facing the developing roller with the recording medium interposed therebetween, and a conductive member is provided between the developing roller and the conductive member. A liquid developing device, wherein an electric field in a direction in which the toner particles move toward the developing roller is applied therebetween. 4. The liquid developing device according to claim 1, wherein a conveying direction of the recording medium is regulated such that the recording medium has a predetermined winding angle and urges the developing roller. A liquid developing device, comprising: 5. The liquid developing apparatus according to claim 1, wherein the recording medium is uniformly formed to have the same polarity as the toner particles before forming an electrostatic latent image on the recording medium. A liquid developing device characterized by being charged. 6. An electrostatic latent image on a previous recording medium formed by means for forming an electrostatic latent image corresponding to an image signal on a recording medium and means for guiding and conveying the recording medium, wherein toner particles are dispersed. A developer having a nonvolatile content of 10% wt to 30% wt, a developer holding unit for holding a predetermined amount of the developer, and a developer in the developer holding unit. A developing roller, which is immersed in a developer and pumps up the developer, abuts against the developing roller, abuts against the developing roller, and a developing belt having a surface roughness of 8 μmRz to 25 μmRz to which the developer on the pumping roller is supplied; A film thickness controlling member for controlling the film thickness of the developer on the developing belt; and a contact portion between the pumping roller of the developing belt and the film thickness controlling member, which is in contact with the developing belt and conveys the developing belt. Outside A transport roller having a length shorter than an inner circumferential length of the developing belt, and having a predetermined contact width in a transport direction of the transport belt at a position where the developing belt is not in contact with the transport roller; The conveying roller rotates in a direction in which a moving direction of the developing belt is in a direction opposite to a conveying direction of the recording medium at a contact position between the developing belt and the recording medium. A liquid developing device for developing an electrostatic latent image on a pre-recording medium.