JP2002278296A - Device for coating liquid developer and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for coating a liquid developer which stabilizes image quality by eliminating unevenness on a surface coated with the liquid developer due to foreign matter by preventing the foreign matter from entering the part between a coating roller and a doctor blade serving as a coating amount restriction member and keeping in contact with the coating roller, and to provide an image forming device at low cost. SOLUTION: The coating device is composed of a coating roller 12 which has its surface engraved in a regular pattern and a coating amount restriction member 15 which controls a coating amount by being made to abut against the surface of the roller and forms a uniform thin layer of the liquid developer 7. The coating roller surface has engraved grooves 23 which are continuous along a single or a plurality of axis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for applying a liquid developer and an image forming apparatus using the same, such as an electrophotographic copying machine, a printer and a facsimile, and more particularly, to an engraving having a regular pattern on the surface. An image forming apparatus including an application roller for forming a uniform thin layer of a liquid developer, comprising an application roller having been processed and an application amount regulating member for controlling an application amount by being brought into contact with the surface of the roller. It is.

[0002]

2. Description of the Related Art In a liquid developing apparatus using a high-viscosity, high-concentration toner as a liquid developer, a thin layer of toner is formed on a developing roller for development. As a thin layer forming means, for example, as shown in Japanese Patent Application Laid-Open No. 11-265122, an application roller having a regular engraving on its surface is used, and an application amount regulating member is brought into contact with the application roller to form a developing roller. The liquid developer is uniformly applied to the liquid developer to form a thin layer of the liquid developer. In the above-described application mechanism, if foreign matter such as dust or paper powder mixed in the liquid developer becomes clogged between the application amount regulating member and the application roller, normal application cannot be performed at that portion. Streaks appear on the image formed by development. In addition, the tip of the coating amount regulating member is in contact with the application roller with a certain contact pressure or more, and if foreign matter is clogged once between the tip of the coating amount regulating member and the coating roller, the foreign matter is removed. It is difficult to remove with normal operation.

[0003]

Therefore, a brush-like foreign matter removing means is provided in the vicinity of the application roller, and foreign matter clogged by opening and closing the application amount regulating member is removed. However, there is a problem in that it is difficult to remove fine dust and the like with a brush, and in long-term use, the hair of the brush comes off and becomes a foreign substance. Opening and closing the contact of the coating amount regulating member in order to remove the foreign matter clogged at the tip of the coating amount regulating member complicates the device, making it difficult to reduce the size of the device and increasing the cost. There was a problem.

The present invention has been made in view of the above background, and an object of the present invention is to prevent foreign matter from entering between a coating roller and a doctor blade as a coating amount regulating member that comes into contact with the coating roller. An object of the present invention is to provide an inexpensive liquid developer application apparatus and image forming apparatus that prevent and prevent the non-uniformity of the liquid developer application surface due to foreign matter and stabilize image quality.

[0005]

According to a first aspect of the present invention, there is provided an application roller having a sculpture having a regular pattern formed on a surface thereof, and a coating amount regulating member for controlling an application amount by contacting the surface of the roller. And a coating device for forming a uniform thin layer of the liquid developer, wherein the engraved shape of the surface of the application roller is continuous in one or more axial directions.

According to a second aspect of the present invention, a foreign matter removing member is provided which comes into contact with the surface of the application roller on the upstream side of the contact position of the application amount regulating member.

According to a third aspect of the present invention, the contact position of the foreign matter removing member is vertically above the liquid surface position of the liquid developer.

According to a fourth aspect of the present invention, the foreign matter removing member is a blade.

According to a fifth aspect of the present invention, the contact pressure of the contact portion of the coating amount regulating member against the surface of the coating roller is higher than the contact pressure of the contact portion of the foreign matter removing member.

According to a seventh aspect of the present invention, an apparatus for applying a liquid developer is provided and an amorphous silicon photosensitive member is used.

According to a ninth aspect of the present invention, the engraving of the surface of the application roller is formed by rolling.

According to a tenth aspect of the present invention, a hardened film is formed on the surface of the application roller by forming an engraving pattern by rolling and then performing a surface treatment.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an example of an embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter, referred to as a copying machine) which is an image forming apparatus for liquid development will be described. Figure 1
3 is a schematic configuration diagram of a developing unit of the copying machine according to the present embodiment. In the copying machine according to the present embodiment, a charging device 2, an exposure device 3, a developing device 4, a transfer roller 5, and a cleaning device 6 are disposed around a photoreceptor 1 as a latent image carrier. As the material of the photoreceptor, a-Si, OPC or the like can be used. As the charging device, a form of a roller or a charger can be used. As the exposure device, an LED or a laser scanning optical system can be used. .

A case where an image is formed by reversal development in the copying machine having the above configuration will be described. The photoreceptor is driven to rotate in a direction indicated by an arrow at a constant speed during copying by a driving means such as a motor (not shown). After being uniformly charged in the dark by the charging charger of the charging device 2, the exposure device 3 irradiates and forms an original light image to form an electrostatic latent image on the outer peripheral surface of the photoconductor 1. Thereafter, the electrostatic latent image is developed while passing through the developing device 4. The developed toner image is transferred by a transfer section including the transfer belt 25, and then transferred to a transfer sheet at a portion (not shown). The transfer sheet passes through a fixing device (not shown) and is discharged outside the apparatus. .

After the transfer, the residual potential of the photoreceptor 1 is removed by a discharging lamp (not shown), and the residual toner is removed by the cleaning device 6 to prepare for the next image formation. As the transfer device, for example, a method using an electrostatic roller, a method using a corona discharge, an adhesive transfer method, a thermal transfer method, or the like can be used. Further, as the fixing device, for example, a thermal transfer method, a solvent fixing, a UV fixing, a pressure fixing and the like can be used.

The developer 7 used in the copying machine of the present embodiment
Is a conventional and commercially available Isopa
r (Exxon ™) as a carrier with low viscosity (1 cSt)
Liquid developer having a high viscosity and a high concentration, not a liquid developer having a low concentration (about 1%). The range of the viscosity and the concentration of the liquid developer 7 is, for example, 50 to 1000.
A material having a concentration of 0 mPa · s and a concentration of 5% to 40% is used. As the carrier liquid, a liquid having a high insulating property such as silicone oil, normal paraffin, IsoparM (Exxon trademark), vegetable oil, or mineral oil is used. Volatility and non-volatility can be selected according to the purpose. The particle size of the toner can be selected from submicron to about 6 μm according to the purpose.

Next, the developing device 4 which is a characteristic part of the present embodiment will be described. As shown in FIG. 1, the developing device 4 includes a developer storage tank 8 for storing a liquid developer 7 therein, a developing roller 9, a sweeper 11, and a coating means. Coating roller 1 with
2. It is mainly composed of the stirring screw 13. A cleaning member 14 made of a metal blade or a rubber blade is provided on each of the developing roller 9 and the sweeper 11.
a and 14b are provided. Each cleaning member 14a,
14b is not limited to the blade and may be a roller type. Further, the application roller 12 is provided with a doctor blade 15 as an application amount regulating blade.

The developing roller and the sweeper 11
Is provided with an elastic layer having conductivity on the outer peripheral surface. Urethane rubber can be used as the material of these elastic layers. The rubber hardness of each elastic layer is preferably 50 degrees or less in JIS-A hardness. The material of each elastic layer is not limited to urethane rubber, but may be any material that has conductivity and does not swell or dissolve in the liquid developer 7. Further, the surfaces of the developing roller 9 and the swivel roller 11 are made of a material which has conductivity and does not swell or dissolve in the liquid developer 7, and the inner layer is in contact with the liquid developer 7. If it is a configuration that does not, as the inner layer, the material of the layer of each elastic body, without restriction of the above conductivity and swelling and dissolution,
What is necessary is just to have elasticity. At this time, the developing bias voltage and the sweep bias voltage need to be applied not from the axis of the developing roller 9 and the sweeper 11 but from the surface.

The layer of the elastic material is formed by a developing roller 9 and a sweeper.
Instead of the structure provided on the photosensitive member 1
It may be a configuration provided on the side. Further, the photoconductor 1 may be constituted by an endless belt-shaped member. The developing roller 9 and the sweeper 11 are formed by coating or a tube so that their surfaces have a smoothness of Rz 3 μm or less.

When the developing roller and the swirler 11 are brought into contact with the photosensitive member 1 at appropriate pressures,
The elastic layer of each roller is elastically deformed to form a developing nip 17 and a removing nip 16. In particular, by forming the developing nip 17, it is possible to secure a certain developing time for the toner of the liquid developer 7 to move and adhere to the photoconductor 1 by the developing electric field in the developing area. Also,
By adjusting the contact pressure, the nip width, which is the width of each nip in the surface movement direction, can be adjusted. Each nip width is set to be equal to or larger than the product of the linear speed of each roller and the development time constant. Here, the development time constant is a time required until the development amount is saturated, and is obtained by dividing a required minimum nip width by a process speed. For example, if the required minimum nip width is 3 mm and the process speed is 300 mm / sec,
The development time constant is 10 msec.

During the developing operation, a thin layer of the liquid developer 7 is formed on the developing roller by the application roller 12. At this time, the thickness of the liquid developer 7 applied on the developing roller 9 was set so that the content of the pigment in the toner carried per 1 cm ^{2 of the} surface was 3 μg or more and 60 μg or less. To this end, a thin layer of liquid developer 7
It was applied to a thickness of 10 to 10 μm. The reason for this is
When the coating thickness of the liquid developer 7 is such that the pigment content in the toner carried per 1 cm ^{2 of the} surface of the developing roller is less than 3 μg, a sufficient amount of the pigment is sufficient for the photosensitive member 1.
This is because there is a possibility that the image density of the image portion is reduced without moving to the image portion of the latent image formed thereon. Further, if the pigment content in the toner carried per 1 cm ^{2 on the} surface of the developing roller is more than 60 μg, the excess toner remaining on the background after development increases, and the removal by the sweep roller is incomplete. This is because there is a possibility of becoming.

The thin layer of the liquid developer 7 formed on the developing roller surface forms a latent image on the photosensitive member 1 when passing through a developing nip 17 formed by the photosensitive member 1 and the developing roller 9. Developed accordingly. That is, in the image portion, the toner moves to the photoconductor 1, and in the background portion (non-image portion), the electric field formed by the developing bias potential and the photoconductor potential causes
The toner is moved to the surface of the developing roller 9 so that the toner does not adhere to the background. However, if a part of the toner in the background does not move to the surface of the developing roller 9 and remains on the photosensitive member 1, it causes fogging. Therefore, the developing device 4 of the copying machine according to the present embodiment is provided with the sweep roller for sweeping (cleaning) the toner causing the fogging (hereinafter, referred to as “fogging toner”). The swivel roller 11 is disposed downstream of the developing roller 9 in the rotation direction of the photosensitive member 1 and is pressed against the photosensitive member 1 so as to sandwich the developed toner layer.
The surface of the swirler 11 removes fog toner on the background while moving at substantially the same speed as the surface of the photoreceptor 1.

In the liquid developing apparatus that performs the above operation, the density of the image is determined by the thickness of the liquid developer 7 applied on the developing roller 9 as a developer carrier. That is, if there is a streak on the surface of the developing roller 9 where the liquid developer is applied, the streak appears on the image as it is.

If a foreign substance enters the contact portion between the doctor blade 15 and the application roller 12, a streak is generated on the application surface, so that a streak appears on the image, and the image quality is significantly impaired. If the liquid developer 7 can be circulated in a complete closed system,
Although there is no foreign matter, it is not possible to form a closed system because it needs to contact the photoconductor 1 in the developing section. However, it is important to make the open portion as small as possible in order to prevent foreign substances from entering the liquid developer 7 as much as possible. Therefore, in the embodiment of the present invention, the developing unit 4
The shape of the unit A and the sweep unit 11A are devised so that there is no opening other than the part necessary for functioning as contact with the photoconductor 1.

The coating roller 12 used in the present invention is a roller having an engraved surface, and an engraved groove 23 having a pattern as shown in FIG. 2 is formed on the surface of the coating roller. The excess amount of the liquid developer 7 attached to the developer is scraped off by a doctor blade 15 serving as a measuring means, and is accurately measured by an engraving groove 23. This is transferred onto a developing roller 9 to transfer the liquid developer 7 to the developing roller 9. A uniform thin layer is formed. The engraving groove 23 formed on the surface of the application roller 12 has a spiral shape, and has a continuous shape in the axial direction of the application roller 12.

For this reason, the foreign matter mixed in the contact portion between the doctor blade 15 and the application roller 12 moves in the axial direction along the spiral groove shape by the rotation of the application roller 12, and exits from this contact portion. Can go. However, in the application roller 12 which is not continuous in a groove shape in the axial direction, the foreign matter cannot move at the discontinuous portion, and the foreign matter is not removed from the contact portion with the doctor blade, and once enters. Since the contaminants cannot come out, continuous streak defects in the sub-scanning direction occur on the image. As described above, by using the groove-shaped application roller 12 of the present invention, the foreign matter that has entered once can be automatically removed, so that the image defect can be made temporary.

At this time, as the angle of the engraving groove 23 with respect to the contact surface of the doctor blade is smaller, the moving speed in the axial direction becomes faster, so that the foreign matter can be removed from the image area in a short time (FIG. 3). However, the resistance to the movement is increased by that amount, and it becomes difficult to move. Therefore,
In the present invention, the groove-shaped coating roller 12 having an angle of 45 degrees is used.

As the application amount regulating member of the application roller 12, a doctor roller 15A for pressing a roller having an elastic layer on its surface can be used instead of the doctor blade 15 described in this embodiment (FIG. 4). in this case,
In order to make the contact with the coating roller 12 in the axial direction as uniform as possible, it is preferable to use a rubber layer of JIS-A 70 degrees or less as the elastic layer. When the doctor roller is used, the doctor roller 15A is used while rotating or rotating in the opposite direction (reverse direction) with respect to the application roller 12, so that a foreign matter is clogged like the doctor blade 15 so that a stripe-shaped coating defect is generated. Less to make. In either case, it is possible to control the amount of application by the rotation speed, but in this case, a mechanism for controlling the rotation speed is required, and there is a problem that the apparatus becomes complicated.
In particular, when rotating in the opposite direction with respect to the application roller 12, a cleaning member for the doctor roller 15A is required, so that the incorporation of foreign matter here becomes a new problem.

If foreign matter enters between the application roller 12 and the doctor blade 15 from the outside, streaks will occur even temporarily. Therefore, in a second aspect of the present invention, a foreign matter removing member 24 is provided on the upstream side of the doctor blade 15 with respect to the rotation direction of the coating roller surface, for removing foreign matter mixed in the liquid developer. Immediately before the doctor blade 15, the foreign matter removing member 24 is
, The foreign matter mixed between the doctor blade 15 and the application roller 12 can be more reliably removed (FIG. 1). Further, the contact position of the foreign matter removing member 24 with the application roller 12 is set at the liquid surface position 10 of the liquid developer 7 in the application device of the liquid developer 7.
By setting the position higher than the vertical direction, foreign matter can be prevented from newly entering the surface of the application roller 12 after contact with the foreign matter removing member 24, and the foreign matter can be more reliably prevented from being mixed. In claim 4, a blade member is used as such a foreign matter removing member 24. As the foreign matter removing member 24 other than the blade member, for example, a brush-like one can be considered. However, the performance of removing foreign matter from the surface of the application roller is inferior. In addition, for example, a sponge member or the like can be considered as the foreign matter removing member 24. However, when the sponge member comes into contact with the application roller 12, its surface is deformed and enters the groove of the application roller 12 to remove the liquid developer 7. There is a risk that it will.

By using the foreign matter removing member 24 as in this embodiment, the foreign matter can be surely prevented from being mixed in, and further, the liquid developer 7 in the groove of the application roller 12 is not excessively removed. . When foreign matter mixed in the liquid developer adheres to the surface of the application roller 12, the foreign matter is prevented from moving by the foreign matter removing member 24, and the foreign matter is axially moved by the spiral engraving groove 23 on the surface of the application roller. Move and be removed. During this time, spots on the coating surface are temporarily generated on the coating roller 12, but the unevenness is leveled out at the contact portion between the doctor blade 15 and the coating roller 12, and becomes almost inconspicuous on the developing roller 9. The generation of streaks on the image due to foreign matter in the agent can be prevented.

If the blade is brought into contact with the engraved coating roller 12 in a state where the liquid is sufficiently supplied, the amount of liquid adhering to the coating roller surface after the blade abutment is determined by The contact pressure slightly changes depending on the contact pressure, and the higher the pressure, the smaller the amount of adhesion. At a certain contact pressure or more, it becomes almost equal to the volume of the groove (FIG. 5).
Therefore, the doctor blade 1 which is a coating amount regulating blade
In No. 5, it is attached so that the contact pressure becomes higher than this value. On the other hand, the foreign matter removing blade, which is the foreign matter removing member 24, is brought into contact with the contact pressure so as to have a contact pressure equal to or less than this value. Can be made more than by the volume. In this way, a sufficient amount of the liquid developer 7 can be supplied to the doctor blade 15, and the amount of liquid developer adhering after passing through the doctor blade can be made uniform. Conversely, if the contact pressure of the foreign matter removing blade is higher, the amount of application is regulated by the passage of the foreign matter removing blade. The toner cannot be leveled by the doctor blade 15 and is directly transferred onto the developing roller 9.

The material of the foreign matter removing member 24 is rubber,
Resin and metal are conceivable, but the rubber member is not suitable because it enters the groove of the application roller 12 due to minute deformation at the contact portion. In the embodiment of the present invention, a PET blade having a thickness of 0.6 mm is used as the foreign matter removing member 24, and a steel blade having a thickness of 0.15 mm is used as the doctor blade 15. Function,
A uniform application surface of the liquid developer 7 is formed on the developing roller 9 without unevenness of the application amount due to the inclusion of foreign matter.

As described above, a high-quality image without streaks could be obtained by the liquid developer developing device and the image forming device provided with the coating device for forming a uniform thin layer of the liquid developer 7. .

The coating roller 12 used in the present invention needs to have a uniform pattern of engraved grooves 23 on its surface in order to form an accurate amount of the liquid developer 7 on the coating roller 12. . As a method of processing such a groove, there is a manufacturing method by cutting, etching, or the like. However, in order to form a more uniform pattern, a manufacturing method by rolling is desirable. In the cutting process, high-precision processing is performed over the entire peripheral surface of the application roller 12, so that processing time is required and processing cost is high. When a chemical reaction such as etching is used, it is difficult to make the depths of the grooves uniform. On the other hand, in rolling, it is easy to transfer the same shape once an accurate hob is made, and in the case of mass production, it can be manufactured at a lower cost than cutting. is there.

In the case of rolling, it is desirable to use a soft material in order to increase the production efficiency, and if steel, low carbon steel such as S25C, SUS XM7, an aluminum alloy or the like is suitable. However, since these materials have low surface hardness and are worn by contact with the doctor blade 15 and the like, a surface treatment is performed after rolling to form a cured film. Examples of the surface treatment method include hard chrome plating and anodic oxidation of an aluminum alloy. As described above, by the manufacturing method in which the cured film is formed by performing the surface treatment after the rolling, it is possible to manufacture the application roller 12 having sufficient durability and an accurate groove shape at a low cost. In the developing device and the image forming apparatus using the application device for the liquid developer 7 using the simple application roller 12, the cost of the machine can be suppressed and the durability can be improved.

The application roller 12 of the present embodiment has a life of 150K or more by using a roller having a Vickers hardness of 700 Hv obtained by rolling the engraved groove 23 in S25C and then subjecting the surface to hard chrome plating. I have.

Further, by using the photosensitive member 1 whose surface is formed of amorphous silicon (a-Si),
It exhibits better mechanical strength than an organic photoreceptor (OPC) and can prolong its life.

[0038]

According to the first aspect of the present invention, foreign matter that has entered between the application roller and the doctor blade, which is an application amount regulating member that comes into contact with the application roller, is caused by the rotation of the application roller.
The surface is moved in the axial direction by the groove having a continuous shape, and foreign matter which causes unevenness of the application surface can be removed. According to such a liquid developer application device, it is possible to prevent defects such as streak formation on a continuous image due to mixing of foreign matter.

According to the second aspect of the present invention, a foreign matter removing member abutting on the application roller is provided in front of the application roller and a doctor blade which is an application amount regulating member abutting on the application roller. It is possible to prevent foreign matter from entering between them, and it is possible to prevent unevenness of the application surface due to foreign matter from entering. According to such a liquid developer application device, it is possible to prevent defects such as streaks on an image due to the incorporation of foreign matter.

According to the third aspect of the present invention, the contact position of the foreign matter removing member is vertically higher than the liquid surface position of the liquid developer so that the coating after passing the foreign matter removing member and before contacting the coating amount regulating member. Foreign matter newly entering the roller surface can be eliminated, foreign matter can be more reliably prevented from entering between the doctor blade and the application roller, and nonuniformity of the application surface due to foreign matter entering can be prevented. According to such a liquid developer application device, it is possible to prevent defects such as streaks on an image due to the incorporation of foreign matter.

According to the fourth aspect of the present invention, by using a blade as the foreign matter removing member, the foreign matter can be more reliably removed and the foreign matter can be prevented from entering between the doctor blade and the application roller. In addition, it is possible to prevent non-uniformity of the application surface due to entry of foreign matter. According to such a liquid developer application device, it is possible to prevent defects such as streaks on an image due to the incorporation of foreign matter.

According to the fifth aspect of the present invention, the function of restricting the amount of liquid developer adhered to the blade, which is the foreign matter removing member, is suppressed, so that the performance of the doctor blade, which is the subsequent amount regulating member, is sufficiently exhibited. The unevenness generated by the foreign matter removing blade can be smoothed to form a uniform coating surface. According to such a liquid developer application device, it is possible to prevent defects such as streak formation on an image due to contamination of foreign matter.

According to the sixth aspect of the present invention, according to the liquid developing apparatus using the coating apparatus which prevents the coating surface from becoming non-uniform due to the inclusion of foreign matter, a high-quality image free from image defects such as streaks can be stably obtained. Can be obtained.

According to the seventh aspect of the present invention, a stable image can be obtained with a highly durable apparatus by using a liquid developing apparatus having a photosensitive member having amorphous silicon as a surface layer.

According to the ninth aspect of the present invention, the engraving on the surface of the cloth roller is manufactured by rolling, so that a high-accuracy application roller can be manufactured stably at low cost.

According to the tenth aspect of the present invention, after forming an engraving groove on a roller surface made of a relatively soft material by rolling and then forming a hardened film by surface treatment, coating can be performed at low cost and with high durability. Rollers can be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a developing unit of a copying machine according to an embodiment.

FIG. 2 is a diagram showing the shape of an engraving groove on the surface of an application roller.

FIG. 3 is a diagram showing the relationship between the angle of the engraving groove of the application roller with respect to the contact surface with the doctor blade and the moving speed of the foreign matter in the axial direction.

FIG. 4 is a view showing another embodiment of the doctor blade.

FIG. 5 shows a contact pressure of a blade contacting an application roller,
FIG. 5 is a diagram illustrating a relationship with the amount of liquid developer adhering to an application roller.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 4 Developing device 7 Liquid developer 9 Developing roller 10 Liquid surface position 11 Sweep roller 12 Application roller 13 Stirring screw 14 Cleaning member 15 Doctor blade 16 Nip 17 Nip 23 Engraving groove 24 Foreign material removing member 25 Transfer belt

Claims (10)

[Claims] A uniform thin layer of a liquid developer comprising an application roller having an engraved surface having a regular pattern formed on its surface and an application amount regulating member for controlling the application amount by contacting the roller surface. A coating device for forming a liquid developer, wherein the engraving shape of the surface of the coating roller is continuous in one or more axial directions. 2. The liquid developer applying device according to claim 1, further comprising a foreign matter removing member that comes into contact with the surface of the applying roller upstream of a contact position of the application amount regulating member. Developer application device. 3. A liquid developer applying apparatus according to claim 2, wherein the contact position of said foreign matter removing member is vertically above the liquid surface position of said liquid developer. Coating device. 4. A liquid developer applying apparatus according to claim 2, wherein said foreign matter removing member is a blade. 5. A liquid developer applying apparatus according to claim 2, wherein a contact pressure of a contact portion of said coating amount regulating member against a surface of said coating roller is adjusted by a contact pressure of said foreign matter removing member. An apparatus for applying a liquid developer, wherein the application pressure is higher than a contact pressure at a contact portion. 6. A liquid developing device comprising the liquid developer applying device according to claim 1. Description: 7. A liquid developing device comprising the liquid developer coating device according to claim 1 and using an amorphous silicon photoreceptor. 8. An image forming apparatus comprising the liquid developing device according to claim 6. 9. A method according to claim 1, wherein the engraving of the surface of the applying roller is formed by rolling. 10. A method according to claim 9, wherein an engraved pattern is formed on said coating roller surface by rolling, and then a cured film is formed by surface treatment.