JP2002287517A - Liquid developing device and liquid image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid developing device and a liquid image forming apparatus by which a high-quality image is formed by preventing fogging of images and carrier liquid is reduced. SOLUTION: In the liquid developing device having at least one developer carriers 42 to carry liquid developer with high viscosity and high concentration formed by distributing toner in carrier liquid and an application member 44 to apply the liquid developer to the developer carrier 42 and to develop a latent image formed on a latent image carrier 1 by the liquid developer carried by the developer carrier 42, it is provided with at least one removal rollers 43 provided on the downstream side in the transfer direction of the latent image carrier of the developer carrier 42 and formed by an elastic body to remove excess developer after development of the latent image carrier 1, a nip forming means 55 to form a nip between the removal roller 43 and the latent image carrier 1, a removing voltage impressing means 52 to impress voltage to the removal roller 43, a rotating and driving means to rotate and drive the removal roller 43, attaching/detaching means 50, 51 to attach/detach the latent image carrier and a cleaning means 43 to clean the removal roller 43.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid developing apparatus and a liquid image forming apparatus used in an electrophotographic dry copying machine, a printer, a facsimile, and the like. At least one developer carrying member for carrying the liquid developer, and an application member for applying the liquid developer to the developer carrying member. The present invention relates to a liquid developing device for developing a latent image formed on an image carrier and a liquid image forming device.

[0002]

2. Description of the Related Art Hitherto, in Japanese Patent Application Laid-Open No. 2000-24208, the present applicant has proposed an image forming method in which a developer carrying member having an elastic layer is brought into contact with a latent image carrying member to form a nip portion. . In this image forming method, a thin layer of a liquid developer is formed on a developer carrier, and the carrier liquid and the toner in the thin layer form the nip portion. And development is performed. On the other hand, the carrier liquid is slightly transferred to the background portion (non-image portion) on the latent image carrier passing through the nip without adhering toner. Even if the toner adheres to the background, the toner can be moved to the developer carrier side and removed while passing through the nip.

[0003]

However, in the image forming method proposed in JP-A-2000-242088, toner adheres to a background portion (non-image portion) on the latent image carrier passing through the nip portion. In some cases, the toner remains as excess toner. In this case, the excess toner may cause fogging of the image. Further, the carrier liquid adhering to the image area and the non-image area is also consumed in excess.

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and an object of the present invention is to provide a liquid developing apparatus capable of forming a high quality image by preventing image fogging and reducing a carrier liquid. An object of the present invention is to provide a liquid image forming apparatus.

[0005]

According to a first aspect of the present invention, there is provided a liquid developing apparatus comprising: at least one developer carrier for carrying a high-viscosity, high-concentration liquid developer in which toner is dispersed in a carrier liquid; An application member for applying the liquid developer to a carrier, and developing the latent image formed on the latent image carrier with the liquid developer carried on the developer carrier. At least one removal roller provided at a downstream side of the carrier in the moving direction of the latent image carrier surface and formed of an elastic body for removing excess developer after development on the latent image carrier; Nip forming means for forming a nip between a roller and the latent image carrier; removing voltage applying means for applying a voltage to the removing roller; rotating driving means for rotating the removing roller; Move the image carrier It is characterized by having a contacting / separating means and a cleaning means for cleaning the removing roller.

According to a second aspect of the present invention, there is provided a liquid developing apparatus.
Wherein the nip forming means forms the nip by means of controlling the pressing force of the removing roller against the latent image carrier.

According to a third aspect of the present invention, there is provided a liquid developing apparatus.
In the above description, the pressing force control means has a mechanism for adjusting the pressing force.

According to a fourth aspect of the present invention, there is provided a liquid developing apparatus.
Wherein the removing voltage applying means to the removing roller comprises a conductive urging member, and the urging member applies the removing voltage by contacting the removing roller.

According to a fifth aspect of the present invention, there is provided a liquid developing apparatus according to the fourth aspect.
The removal voltage applying means is provided with a conductive wear member on the contact surface with the removal roller so that the contact portion between the removal roller and the removal voltage applying means is worn.

[0010] The liquid developing apparatus according to the sixth aspect is the fourth aspect.
Wherein the removing voltage applying means for applying the removing voltage to the removing roller applies the removing voltage by contacting the core of the removing roller.

[0011] The liquid developing apparatus according to claim 7 is the first aspect of the present invention.
In the rotation driving means, a latent image carrier end gear is disposed at an end of the latent image carrier, and a removal roller end gear is provided at an end of the removal roller so as to mesh with the latent image carrier end gear. And the removing roller end gear rotationally drives the removing roller.

[0012] The liquid developing apparatus according to the eighth aspect is the seventh aspect.
Wherein the removing roller is rotationally driven such that the surface moving speed of the removing roller is substantially equal to the surface moving speed of the latent image carrier.

According to a ninth aspect of the present invention, there is provided a liquid developing apparatus according to the seventh aspect.
Wherein the one-way clutch is disposed on the removing roller end gear.

According to a tenth aspect of the present invention, in the liquid developing device of the first and second aspects, the removing roller is separated from the latent image carrier by a displacement device, and the removing roller is moved by the pressing force control means to the latent image. It is characterized in that it comes into contact with the carrier.

In a liquid developing apparatus according to an eleventh aspect, in the tenth aspect, the contacting / separating means has a cam having a displacement device, and the cam is rotated to separate the removing roller from the latent image carrier. It is characterized by the following.

According to a twelfth aspect of the present invention, in the liquid developing apparatus according to the first aspect, the removing roller is constituted by a cored bar and a laminated structure of one or more layers.

According to a thirteenth aspect of the present invention, in the liquid developing device according to the twelfth aspect, the removal roller formed of an elastic body has a volume resistance of 10 ⁹ Ωcm or less.

According to a fourteenth aspect of the present invention, in the liquid developing device according to the twelfth aspect, the hardness of the removing roller formed of an elastic material is 50 degrees or less (JIS-A).

According to a fifteenth aspect of the present invention, in the liquid developing apparatus according to the twelfth aspect, the removing roller formed of an elastic material swells in the carrier liquid of the developer and does not impregnate the carrier liquid. .

A liquid developing apparatus according to a twelfth aspect is the liquid developing apparatus according to the twelfth aspect, wherein the surface layer of the removing roller formed of an elastic body is a film layer of 100 μm or less.

A liquid developing device according to a twelfth aspect of the present invention is the liquid developing device according to the twelfth aspect, wherein the removal roller surface layer formed of an elastic body is a film layer having a volume resistance of 10 ⁹ Ωcm or less.

In the liquid developing device according to the present invention, the direction in which the toner is moved toward the image portion between the image portion of the latent image on the developer carrying member and the developer carrying member. A developing voltage applying means for applying a voltage to generate an electric field of the latent image, and an electric field in a direction of drawing excess toner floating between a background portion of the latent image and the removing roller to the removing roller toward the removing roller. And a removing voltage applying means for applying a voltage for generating an electric field that does not peel off the toner adhered to the image portion.

In a liquid developing apparatus according to a nineteenth aspect, in the liquid developing apparatus according to the eighteenth aspect, the surface moving speed of the developer carrier is:
It is characterized by being substantially equal to the latent image carrier surface moving speed.

According to a twentieth aspect of the present invention, there is provided a liquid image forming apparatus, wherein the latent image carrier, a latent image forming means for forming a latent image on the latent image carrier, and a latent image on the latent image carrier are visualized. Developing means,
Transfer means for transferring a visible image on the latent image carrier to a transfer material, wherein the developing means is
19. A liquid developing device according to claim 19, further comprising:

According to a twenty-first aspect of the present invention, in the liquid developing apparatus or the liquid image forming apparatus according to the first or twentieth aspect, the removing roller is a latent image carrier when the liquid developing apparatus or the liquid image forming apparatus is stopped. It is a feature that is separated from.

According to a twenty-second aspect of the present invention, there is provided a liquid developing apparatus, wherein at least one developer carrier for carrying a high-viscosity, high-concentration liquid developer in which toner is dispersed in a carrier liquid; And an application member for applying a developer, wherein the latent image formed on the latent image carrier is developed by the liquid developer carried on the developer carrier. At least one removing member for removing excess toner and carrier after development on the latent image carrier is provided on the downstream side of the carrier surface moving direction, and the removing members clean the surface with a roller. Means, wherein the cleaning means is a blade member, and a contact position of the removing member with the roller is not more than a vertical center position.

According to a twenty-third aspect of the present invention, in the liquid developing apparatus according to the twenty-second aspect, the cleaning blade abuts on the removing roller at a position of an angle θ with respect to the horizontal surface of the removing roller,
The cleaning blade comes into contact with the removal roller at an angle α formed by the blade and a tangential direction at the contact point of the blade, and the cleaning blade is arranged so that the angle θ is larger than the angle α.

According to a twenty-fourth aspect of the present invention, there is provided the liquid developing device according to the twenty-second aspect, wherein the hardness of the cleaning means is in accordance with JISA5.
It is characterized by being a rubber member of not less than 0 degrees and not more than 80 degrees.

A liquid developing apparatus according to a twenty-fifth aspect is characterized in that, in the twenty-second aspect, the cleaning means has a material having an elastic constant of 100 MPa or more and 5000 MPa or less.

According to a twenty-sixth aspect of the present invention, in the liquid developing apparatus according to the twenty-second aspect, the cleaning means has a hardness of JISA50.
It is characterized by comprising a blade having a configuration in which an elastic body of not less than 80 degrees and not more than 80 degrees is bonded to a thin plate of a rigidity imparting member.

A liquid developing apparatus according to a twenty-seventh aspect is characterized in that, in the twenty-second aspect, the cleaning member is subjected to an oil-repellent treatment.

A liquid developing apparatus according to a twenty-eighth aspect of the present invention is the liquid developing apparatus according to the twenty-second to twenty-seventh aspects, further comprising conveying means for moving the removed toner in the axial direction in the vicinity of the cleaning blade.

A liquid developing apparatus according to a twenty-ninth aspect is the liquid developing apparatus according to the twenty-second to twenty-eighth aspects, wherein the angle of the cleaning blade is a minus direction with respect to the vertical, and a moving member is provided near the cleaning blade. I do.

According to a thirtieth aspect of the present invention, in the liquid developing device according to the twenty-second to twenty-ninth aspects, the cleaning blade and its holding portion are electrically floating from the main body of the device, and have substantially the same potential as the developer carrier. A bias is applied so that

In the liquid developing apparatus according to the present invention, when the electric resistance of the cleaning blade material is 10 ¹² Ωcm or more, the cleaning blade and its holding portion are electrically floated from the apparatus main body. And this part is grounded.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an example of an embodiment in which the present invention is applied to an electrophotographic image forming apparatus (hereinafter, referred to as an image forming apparatus) which is a liquid image forming apparatus will be described. FIGS. 1 to 4 are schematic diagrams of the main parts of the image forming apparatus according to the present embodiment. In the image forming apparatus according to the present embodiment, a charging device 2, an exposure device 3, a developing device 4, a transfer device 5, a cleaning device 6, and the like are provided around a photosensitive drum 1 as a latent image carrier. As the material of the photosensitive drum 1, a-Si, OPC, or the like can be used. Further, as the exposure device 3, an LED, a laser scanning optical system, or the like can be used.

A case where an image is formed by reversal development in the image forming apparatus having the above configuration will be described. The photosensitive drum 1 is driven to rotate at a constant speed in the direction of the arrow at the time of copying by a driving means such as a motor (not shown). After being uniformly charged to about 600 V in the dark by a charging roller (not shown) of the charging device 2, a document light image is irradiated and formed by the exposure device 3, and an electrostatic latent image is formed on the outer peripheral surface of the photosensitive drum 1. Carried on top. Thereafter, the electrostatic latent image is developed while passing through a portion of the developing device 4. The toner image developed into the electrostatic latent image is transferred to transfer paper by the transfer device 5. After the transfer paper is separated from the photosensitive drum 1, the residual toner is removed by the cleaning device 6. After that, the residual potential is removed from the surface of the photosensitive drum 1 by an unillustrated discharging lamp to prepare for the next copy. The transfer paper onto which the toner image has been transferred passes through a fixing device (not shown) and is discharged outside the apparatus. The transfer device 5 may be, for example, a method using an electrostatic roller (for example, a transfer roller 7 and a transfer belt 8 as illustrated), a method using corona discharge, an adhesive transfer method, a thermal transfer method, and the like. Can be used. As the fixing device, for example, a thermal transfer method, a solvent fixing method, a pressure fixing method, or the like can be used.

The developer 40 used in the image forming apparatus of the present embodiment is an Is
low viscosity (1)
This is not a liquid developer having a low concentration (about 1%) but a high viscosity and a high concentration. This developer 40
The viscosity and concentration ranges are, for example, 50 cS
A material having a concentration of t to 5000 cSt 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. Further, the particle size of the toner ranges from submicron to 6 μm.
It can be selected according to the purpose up to about μm.

Next, the developing device 4 which is a feature of the present embodiment will be described. The developing device 4 mainly includes a developer storage tank 41 for storing a developer 40 therein, a developing roller 42, a sweep roller 43, a gravure roller 44 as an application unit, a gear pump 45, and a stirring roller 46, as shown in FIG. ing. The developing roller 42 and the sweep roller 43 are provided with cleaning members 47 and 48 each made of a metal blade or a rubber blade. Each of the cleaning members 47 and 48 is not limited to a blade and may be a roller type. The gravure roller 44 has a doctor blade 49.

The developing roller 42 and the sweep roller 4
3 is a layer 42 of an elastic body having conductivity on the outer peripheral surface.
a, 43a are provided. These elastic layers 42
Urethane rubber can be used as the material of a and 43a. The rubber hardness of the layers 42a and 43a of each elastic body is desirably 50 degrees or less in JIS-A hardness. The material of the layers 42a and 43a of each elastic body is not limited to urethane rubber, but may be any material that has conductivity and does not swell or dissolve in a solvent. Further, instead of providing the elastic layer on the developing roller 42 and the sweep roller 43, the elastic layer may be provided on the photosensitive drum 1 side. Further, although the photoconductor is formed of a drum here, the photoconductor may be formed of an endless belt-shaped member. The sweep roller 43 is formed by coating or a tube so that the surface thereof has a smoothness of Rz 3 μm or less.

The developing roller 42 and the sweep roller 4
When the roller 3 is brought into contact with the photosensitive drum 1 at an appropriate pressure, the elastic layers 42a and 43a of the respective rollers are elastically deformed to form a developing nip and a removing nip. In particular,
By forming the developing nip, it is possible to secure a certain developing time for the toner of the developer 40 to move and adhere to the photosensitive drum 1 by the developing electric field in the developing area. Further, by adjusting the contact pressure, it is possible to adjust the nip width, which is the size of each nip portion in the surface movement direction. Each nip width is set to be equal to or more than the product of the linear speed of each roller and the development time constant. Here, the development time constant is the time required until the development amount is saturated, and is obtained by dividing the nip width by the process speed. For example, if the nip width is 3 mm and the process speed is 300 mm / sec, the development time constant is 10 msec.

During the developing operation, the developing roller 4
2, a thin layer of the developer 40 is formed by the gravure roller 44. At this time, the thickness of the developer 40 applied on the developing roller 42 was set such that the pigment content in the toner carried per 1 cm ^{2 of the} surface thereof was 0.1 μg or more and 2 μg or less. For this purpose, a thin layer of the developer 40 was applied to a thickness of 5 to 10 μm. The reason is that the coating thickness of the developer 40 is 1c on the surface of the developing roller 42.
The pigment content in the toner carried per m ² is 0.1
If the thickness is smaller than μg, a sufficient amount of the pigment does not move to the image portion of the latent image formed on the photosensitive drum 1, and the image density of the image portion may be reduced. If the thickness of the toner carried per 1 cm ^{2 of the} surface of the developing roller 42 is larger than 2 μg, the excess toner remaining on the background after development is increased, and the removal by the sweep roller 43 is difficult. This is because there is a risk of becoming incomplete.

The thin layer of the developer 40 formed on the surface of the developing roller 42 passes through a developing nip formed by the photosensitive drum 1 and the developing roller 42. In general, in the electrophotographic developing device 4, the surface moving speed of the developing roller is set to be higher than the surface moving speed of the photosensitive drum 1 in order to send a sufficient amount of toner to an area between the photosensitive drum 1 and the developing device 4. Is set to For this reason, since the toner has a high moving speed with respect to the surface of the photosensitive drum 1, a positional shift occurs between the toner and the latent image. A bad phenomenon appears. This phenomenon is also observed in liquid development. In the image forming apparatus according to the present embodiment, the surface of the developing roller 42 and the surface of the photosensitive drum 1 move at substantially the same speed, and the velocity vector in the tangential direction of the photosensitive drum 1 relative to the toner is changed. Since it is not provided, the above phenomenon does not occur.

The developing roller 42 includes the photosensitive drum 1
The surface potential (developing bias voltage lower than 600 V (400
V) is applied, and 5
A developing electric field is generated between the image surface and the image surface when the voltage becomes 0 V or less. FIGS. 9A and 9B show the developer 4 in the developing nip.
It is the figure which showed the state of 0 typically. In the image portion of the photosensitive drum 1, as shown in FIG. 9A, the toner 40a in the developer 40 moves to the photosensitive drum 1 by the electric field to visualize the latent image. On the other hand, in the background portion (non-image portion), as shown in FIG. 9B, the toner 40a is moved to the surface of the developing roller 42 by the electric field formed by the developing bias potential and the photosensitive drum 1 potential. The toner 40a is prevented from adhering to the portion.

However, if a part of the toner 40a in the background does not move to the surface of the developing roller 42 and remains on the photosensitive drum 1 side, it causes fogging. Therefore, the developing device 4 of the image forming apparatus according to the present embodiment is provided with the sweep roller 43 for sweeping (cleaning) the toner 40c (hereinafter referred to as “fog toner”) that causes the fog. The sweep roller 43 is disposed downstream of the developing roller 42 in the rotation direction of the photosensitive drum 1 and is pressed against the photosensitive drum 1 so as to sandwich the developed toner layer. The surface of the sweep roller 43 moves at substantially the same speed as the surface of the photosensitive drum 1. FIGS. 10A and 10B are diagrams schematically showing the state of the developer in the removal nip formed by the photosensitive drum 1 and the sweep roller 43. FIG.

The sweep roller 43 applies a toner layer surface potential (100 to 100) on the photosensitive drum 1 so as not to return the toner 40a from the developed toner layer to the sweep roller 43.
A bias voltage (250 V) close to 200 V) is applied. In the background portion, as shown in FIG. 10B, the floating fog toner 40c is moved to the sweep roller 43 by an electric field generated by the difference between the potential of the background portion of the photosensitive drum 1 and the potential due to the bias voltage. Let it. At this stage, the developer layer in the background portion is about half the thickness of the developing nip portion of the developing roller 42, and the toner density is reduced to about 20% of the density before development.
Oc is easily removed. This makes it possible to completely prevent fogging of the background. The above relationship between the potentials can be shown as follows.

That is, photoconductor potential>VB1>VB2> toner layer potential. Here, VB1 is a potential between the photosensitive drum 1 and the developing roller 42, and VB2 is a potential between the photosensitive drum 1 and the sweep roller 43.

By providing the sweep roller 43, about half of the excess carrier liquid adhering to the background on the photosensitive drum 1 during development can be removed.

Further, since the fog toner 40c can be efficiently removed by the sweep roller 43, a little fog toner 40c may remain in the developing nip between the photosensitive drum 1 and the developing roller 42, and the fog removing electric field is reduced. (Developing bias applied to developing roller 42 and photosensitive drum 1
(Potential difference from the charged potential) can be suppressed low. Therefore, the charging potential of the photosensitive drum 1 can be reduced. As a result, the durability of the photosensitive drum 1 is improved,
Various advantages such as a reduction in the load on the charging roller 2 and a reduction in the exposure power occur.

In the image forming method described in the prior art, development and removal of fog toner on the background can be performed simultaneously by the developer carrier. However, it is necessary to secure a relatively long developing time (for example, about 40 msec), and it is necessary to increase a developing nip width formed between the latent image carrier and the developer carrier. In this conventional image forming method, since the nip portion is formed by bringing the developer carrier having the elastic layer into contact with the latent image carrier, the contact pressure is increased in order to increase the development nip width. Tends to. On the other hand, in the developing device 4 of the image forming apparatus according to the present embodiment, since the sweep roller 43 is provided,
In the developing roller 42, the function of developing and the function of removing the fog toner 40c can be separated, the developing nip width can be reduced, and the contact pressure can be reduced (for example, 0.3).
kgf / mm or less). Thus, the load applied to the photosensitive drum 1, the developing roller 42, and the sweep roller 43 can be reduced, and the durability can be improved.

In the above embodiment, the case where an image is formed by reversal development has been described. However, an image can be formed by regular development. In the case of the normal development, the relationship of each potential is set as follows in the image forming apparatus having the above configuration.

That is, photoconductor potential> toner layer potential ≧ VB2>VB1> non-image portion potential. Here, VB1 is a potential between the photosensitive drum 1 and the developing roller 42, and VB2 is a potential between the photosensitive drum 1 and the sweep roller 43.

As a specific example of the potential, the photoconductor potential is 600 V, the toner layer potential is 200 to 300 V, and VB2
200 V, VB1 at 100 V, non-image part potential at 50 V
Set to.

The sweep roller 43 is connected to the photosensitive drum 10.
It has approximately the same length as the image width drawn above,
As shown in FIG. 6, a metal core 506a formed of a rigid body such as stainless steel, a sweep roller main body 506b having elasticity formed around the metal core 506a, and a surface film formed on the surface of the sweep roller main body 506b Layer 506
d. Reference numeral 506c indicates the surface of the sweep roller 43. As the elastic member forming the sweep roller main body 506b, a foam such as polystyrene, polyethylene, polyurethane, polyvinyl chloride, NBR (nitrile butylene rubber), silicon rubber,
There is a rubber member of low hardness such as urethane rubber. The sweep roller surface layer 506d is formed of a conductive member that does not swell in silicon oil which is a carrier liquid of the liquid developer 508 described later, for example, a urethane rubber material. When a removing voltage is applied from the core metal 506a of the sweep roller 43, the electric resistance value of the sweep roller 43 is a synthetic rubber-based composite in which conductive particles such as carbon black are dispersed,
It is preferable that the thickness is not more than 10 ⁹ Ωcm. The removal voltage was applied by pressing the end face of the cored bar 506a with a leaf spring such as a phosphor bronze plate and making contact with it. In particular, although a leaf spring has been described as a bias applying unit of the sweep roller 43, the present embodiment is not limited to this.

Further, the elastic material having conductivity often increases in hardness due to dispersion of conductive particles such as carbon black, and a desired resistance value may not be obtained for the elastic material in some cases. In this case, the sweep roller surface layer 506d is formed, and it is desirable that the volume resistance value is 10 ⁹ Ωcm or less.
The electrode may be directly contacted from the surface of the third electrode. The sweep bias was applied by pressing against the surface of the sweep roller 43 with a leaf spring such as a phosphor bronze plate and making contact therewith. As the sweep bias applying means, a cleaning blade formed of a conductive material may be used. In particular, although a leaf spring has been described as the bias applying means of the sweep roller, the present embodiment is not limited to this.

The method of forming the surface layer 506d on the surface of the sweep roller body 506b includes, for example, a method of coating the surface of the sweep roller body 506b with a synthetic rubber-based composite in which conductive particles such as carbon black are dispersed. There is a method in which the sweep roller body 506b is covered with a heat-shrinkable tube having conductivity, and heat is applied to the heat-shrinkable tube to cause heat shrinkage. Alternatively, the sweep roller body 506b may be formed inside the surface layer 506d by injecting an elastic material into the inside of a tube having conductivity or foaming the injected elastic material. As the conductive tube, polyimide, polycarbonate,
A resin tube such as nylon or a metal tube such as nickel is used. As the heat-shrinkable tube having conductivity, a resin tube such as PFA or PTFE is used. Particularly, in order to prevent the developer from adhering to the sweep roller, the PFA or P having a volume resistance of about 10 ⁶ Ωcm is used.
The TFE tube performed well. Further, by forming the surface layer 506d on the sweep roller 43,
The increase in hardness due to impregnation of the elastic material with the carrier liquid and addition of the conductive additive could be suppressed. These tubes are preferably seamless so-called endless tubes. Note that the sweep roller body 506b may be formed of an elastic member such as urethane rubber that does not swell in silicone oil.
It is not necessary to form the surface layer 506d on the surface of b. However, in order to be able to apply an electric developing bias to the sweep roller 43, the sweep roller body 506b
The surface of the roller is conductively processed or the sweep roller body 506b
It is necessary to make the electric resistance value a desired value by adding conductive fine particles to the elastic member forming the above.

The sweep roller 43 is disposed so as to contact the photosensitive drum 1.
, That is, in the direction following the photosensitive drum 1. In the sweep roller 43, a nip width T is formed in the developing region by elastic deformation caused by a pressing force of the sweep roller 43 on the photosensitive drum 1. Note that the hardness of the sweep roller 43 is 50
Degree JIS-A or less, 30 degree JIS
Good results were obtained below -A. Hardness is 50 degrees JIS-
If it is more than A, it is too hard, so that an optimal nip and pressing force cannot be realized to make the liquid developer layer on the sweep roller 43 come into contact with the image on the photosensitive drum 1 while maintaining the image. As will be described later, in order to obtain a desired nip, the hardness of the sweep roller is determined by the diameter of the photosensitive drum 1 and the diameter of the sweep roller. It is necessary to install the sweep roller so as to form a minute gap or interval between the sweep roller and the photosensitive drum 1. For this reason, installation of the sweep roller becomes difficult. The nip width T generated by the elastic deformation of the sweep roller is set in relation to a development time constant defined by an electric circuit including a capacitance and a resistance component formed by the developing roller, the developer layer, and the photosensitive drum 1. You. The adjustment of the pressing force of the sweep roller against the photosensitive drum 1 is performed by disposing the contact rollers 507 in contact with the photosensitive drum 1 on both sides of the sweep roller 43, and using the contact rollers 507 having different outer diameters. Performed by replacing. When the elastic material of the sweep roller 43 is solid, the film tube on the surface is 100 μm
If it is larger than 100, the elasticity cannot be obtained.
It is necessary to be less than μm. Further, when the outer diameter of the sweep roller 43 was 24φ, a good effect was obtained with a 70 μm film layer. In addition, as shown in FIG. 7, it is good also as a structure without a contact roller. FIG. 8 shows a state in which the sweep roller 43 is pressed against the photosensitive drum 1 in that case.

When the elastic material of the sweep roller 43 is a foam, the average pore diameter is desirably 300 μm or less. If the film tube has a thickness of 10 μm or less, pores appear in the image. ~ 70 μm
Is preferred.

The developing roller 42 and the sweep roller 4
When the roller 3 is brought into contact with the photosensitive drum 1 at an appropriate pressure, the elastic layers 42a and 43a of the respective rollers are elastically deformed to form a developing nip and a removing nip. In particular,
By forming the developing nip, it is possible to secure a certain developing time for the toner of the developer 40 to move and adhere to the photosensitive drum 1 by the developing electric field in the developing area. Further, by adjusting the contact pressure, it is possible to adjust the nip width, which is the size of each nip portion in the surface movement direction. Each nip width is set to be equal to or more than the product of the linear speed of each roller and the development time constant. Here, the development time constant is the time required until the development amount is saturated, and is obtained by dividing the nip width by the process speed. For example, if the nip width is 3 mm and the process speed is 300 mm / sec, the development time constant is 10 msec.

The developing roller 42 and the sweep roller 4
3 is a layer 42 of an elastic body having conductivity on the outer peripheral surface.
a, 43a are provided. These elastic layers 42
Urethane rubber can be used as the material of a and 43a. The rubber hardness of the layers 42a and 43a of each elastic body is desirably 50 degrees or less in JIS-A hardness. The material of the layers 42a and 43a of each elastic body is not limited to urethane rubber, but may be any material that has conductivity and does not swell or dissolve in a solvent. Further, instead of providing the elastic layer on the developing roller 42 and the sweep roller 43, the elastic layer may be provided on the photosensitive drum 1 side. Further, the photoconductor may be constituted by an endless belt-shaped member. The sweep roller 43 is formed by coating or a tube so that the surface thereof has a smoothness of Rz 3 μm or less.

As shown in the figure, a sweep roller unit includes a removing roller (hereinafter, a sweep roller), a cleaning blade, a removed developer passage, a removed developer conveying screw, and a sweep roller voltage application electrode. In the sweep roller unit, a sweep roller and a cleaning blade are integrally formed by a holding member, and the holding member is further provided with a removed developer passage and a removed developer conveying screw. A driving gear is disposed at the end of the sweep roller core.

In the developing device of the present invention, the electrostatic latent image formed on the photosensitive drum 1 is developed with the thin developer layer formed on the developing roller 42, and the excess fog toner and carrier liquid are collected. . The undeveloped developer remaining without developing the thin developer layer on the developing roller 42 during the developing process is collected by a cleaning blade 47 or the like, and excess fog toner and carrier liquid on the photosensitive drum 1 are removed by the sweep roller 43.
The developer is collected by a cleaning blade, and the collected developer is collected by a not-shown conveying means such as a screw. Further, an image on the photosensitive drum 1 to be described later is transferred to a transfer member or a recording member, and the developer remaining on the photosensitive drum 1 without being transferred is also collected and collected. The collected developer is subjected to a recycling process (not shown), and is used again as a developer in the developing process. Regarding the reuse of the developer, the reusable developer differs depending on the monochrome image forming apparatus, the full-color image forming apparatus, and the apparatus configuration. In this embodiment, an example is described, and the present invention is not limited to this.

As the reuse process, density adjustment, re-dispersion of toner particles, and the like are performed.

As shown in FIG. 5C, the electrode 52 of the sweep voltage has an electrode member 53 made of abradable copper material on the end face of the metal core 506a and disposed on a leaf spring 54 as an urging member. It was composed of electrodes 52. Since the wearable copper material is provided for the electrode 52 on the leaf spring 54, the core metal 506a is provided.
The contact between the electrode 52 and the electrode 52 was not affected by the contamination of the metal core 506a, and stable contact was made possible, and the sweep voltage functioned stably.

The sweep roller unit is provided with a contact / separation mechanism in order to prevent the sweep roller 43 from being permanently deformed. The contact / separation mechanism brings the sweep roller 43 into contact with / separates from the photosensitive drum 1 by rotating the sweep roller unit with the contact / separation cam 50 as shown. Contact cam 5
0 (position indicated by a solid line in FIG. 1, FIG. 2
Position indicated by broken line. ), The sweep roller 43 and the photosensitive drum 1 come into contact with each other at a desired nip, which will be described later. Moves the follower cam follower 51 to the sweep roller 43
Are pushed out in a direction to separate the photosensitive drum 1 from the sweep roller 43. The sweep roller unit applies a force to press the spring 55 in a direction in which the sweep roller 43 contacts the photosensitive drum 1. The contact / separation cam 50 uses a photo sensor as shown in the drawing, and a position detectable filler corresponding to the positions A and B of the contact / separation cam 50 is provided. Operated by a roller contact / separation motor. Although the top view shows only one end, a contact / separation cam and a contact / separation cam follower are arranged on the rotation shaft of the contact / separation cam on the other side as well.

The image forming apparatus of this embodiment maintains the state of the above-mentioned contact / separation cam position B when no print job is generated, in the idling state, when the power is turned off, and the like. Was prevented.

The photosensitive drum 1 and the sweep roller 4
The nip 3 can perform displacement control to press the sweep roller 43,
When an error occurs in the positional relationship between the photosensitive drum 1 and the photosensitive drum 1, the nip change is large, and the sweep roller 43 and the photosensitive drum 1
Requires high precision. However, in the present embodiment, the nip was formed by controlling the pressing force, whereby a stable nip independent of the processing accuracy of the component could be formed. Specifically, the sweep roller unit is provided with a biasing unit using a spring, and a constant pressure is constantly applied to the photosensitive drum 1. In addition, non-uniform nips due to errors in the assembly of the parts may cause the desired nip to be formed by rotating the adjustment screw and changing the spring length. Therefore,
In this embodiment, the sweep roller 43 can form a uniform nip in the longitudinal direction of the sweep roller by controlling the pressing force on the photosensitive drum 1.

In this embodiment, in order to drive the sweep roller 43 at the same speed as the circumferential speed of the photosensitive drum 1, a gear 51 is provided at the end of the photosensitive drum 1. The gear was similarly arranged at a position corresponding to. In order to prevent image unevenness corresponding to the number of gear teeth perpendicular to the image output direction, an image having no unevenness could be obtained by using a gear having an oblique field shape.

Although this embodiment is not suitable for miniaturization, this embodiment has been described in particular with the method of applying a driving force from the photosensitive drum 1 to the sweep roller 43. However, a motor for independently driving the sweep roller 43 is provided. No problem.

In the embodiment of the present invention, a driving force is applied from the photosensitive drum 1 to the sweep roller 43 via a gear. Further, both gears 51 are designed such that the sweep roller 43 and the photosensitive drum 1 rotate 1: 1. But,
The sweep roller 43 is pressed to form a nip,
It is deformed. Therefore, although the angular velocity of the surface of the photosensitive drum 1 and the angular velocity of the sweep roller 43 are rotated at 1: 1, the surface velocity of the photosensitive drum 1 and the sweep roller 43 are rotated.
There is a difference in the surface velocities. That is, since the sweep roller 43 is deformed and rotated, the actual surface speed of the sweep roller 43 is slightly higher than the surface speed of the photosensitive drum 1. Therefore, in order to match the difference between the surface speed of the photosensitive drum 1 and the surface speed of the sweep roller 43 with the surface speed of the photosensitive drum 1, a one-way clutch is provided in the gear portion of the sweep roller 43, and When the surface speed is high, the surface slips to match the surface speed of the photosensitive drum 1. That is, a one-way clutch that slides in the rotation direction of the sweep roller is provided. By introducing the one-way clutch, especially when the developer was not attached on the photosensitive drum 1, the sweep roller rotated particularly well and stably.

FIG. 11 is an enlarged view of the cleaning section according to the present invention. This figure shows the relationship between both the developing roller 42 and the sweep roller 43 and the respective cleaning blades. Here, the sweep roller 43 will be described as a representative.

Since the developer used in this embodiment has the above-mentioned high concentration and high viscosity, when the developer on the removing roller is collected by the cleaning blade 48, the fluidity of the toner is poor.
It was difficult to easily develop, collect, and reuse.

Thus, the angle α between the tangent to the removal roller and the blade affects the cleaning performance. The smaller the angle α is, the better the cleaning performance is. In particular, about 10 to 30 degrees is appropriate for obtaining sufficient cleaning properties.

In order to recover the developer removed by the cleaning blade 48 by free fall, the relationship of the contact position (the angle θ shown in the drawing) becomes even more important. In order to reduce the accumulation of the developer on the tip of the cleaning blade 48, the contact condition of the blade 48 with the removing roller has a great effect. In order to collect the developer using gravity, it is preferable that the removing roller be located in the third and fourth quadrants. Therefore, the larger the angle θ of the illustrated contact position is, the more advantageous it is. If this angle is 90 degrees or more, the thickness of the blade itself hardly affects. Further, it is desirable that the angle θ is arranged to be larger than the angle α. However, it is very difficult to contact the blade 48 at such a position.

Further, since the cleaning blade 48 has a thickness, the developer accumulates depending on the thickness of the contact portion. Therefore, if the thickness of the blade 48 can maintain the overall rigidity of the blade 48,
The thinner, the better. In this embodiment, when the blade 48 is formed of a highly rigid member such as a metal or a resin, the thickness is 1 mm or less, preferably 0.15 mm.

As shown in FIG. 11B, by chamfering the edge of the back surface of the contact portion, the overall rigidity of the blade 48 is sufficiently maintained, and the amount of liquid developer pooled at the tip of the blade 48 is reduced. Reducing.

Further, an example was shown in which the edge of the tip was chamfered to reduce the thickness of the tip of the blade 48. However, as shown in FIGS. Can also.

By the way, the metal blade has sufficient rigidity even if it is thin, and it is possible to obtain a contact pressure necessary for cleaning. However, such a metallic blade has a problem that the roller surface is damaged. Therefore, in claim 23 of the present invention, the cleaning is performed by the blade 48 of the resin member. The resin member has an elastic constant of 10 times or more as compared with an elastic constant of 2 to 10 MPa of a normal rubber material, and sufficient rigidity can be obtained even when the thickness is reduced to half or less. If the free length is the same, the bending stiffness of the plate is proportional to the cube of its thickness and proportional to the elastic constant, so if the thickness is reduced by half, the elastic constant is increased by eight times. Bending rigidity can be obtained. For example, if a resin member having an elastic constant of 300 MPa is used, sufficient rigidity can be obtained with a thickness of 1 mm. Further, the resin member has a lower hardness than metal, and is less likely to damage the surface of the removing roller.

With a resin blade, it is difficult to reduce the angle R at the cleaning edge in processing, and the cleaning performance is inferior to that of a rubber blade. Then, the thin rubber blade 58 is replaced with the metallic thin plate 57.
Adhering to the substrate realizes higher cleaning performance. FIG. 13 shows an embodiment in which a rubber blade having a thickness of 1 mm is bonded to a 0.15 mm SUS plate. The removal roller can be cleaned without damaging the surface of the removing roller by the rubber, and the contact pressure required for cleaning can be generated by the metal plate. Also, there is no need to create rigidity to obtain the contact pressure with the rubber blade itself,
The thickness of the entire blade can be reduced to about 1 mm.

The high-viscosity liquid developer used in the apparatus of the present invention generally has a thixotropic property, and the viscosity increases with the passage of time. It is necessary to exert force. Due to such a property, the viscosity increases while flowing along the blade surface, and the liquid developer cannot move due to gravity only due to its own weight, and there is a problem that the liquid developer adheres to the back surface of the blade.
If it adheres onto the blade and does not flow, a wasteful space and a liquid developer are required there, which hinders downsizing of the apparatus and running costs. Therefore, in claim 27 of the present invention, this portion of the cleaning blade is subjected to an oil-repellent treatment to reduce the physical adhesion of the liquid developer to the blade surface, thereby preventing the liquid developer from adhering. In this apparatus, a fluorine-based coating agent is used as an oil repellent. Generally, such a fluorine-based coating agent needs to be heated to 100 ° C. or more and adhere to the uncoated surface, and it is difficult to treat the resin member. Can be processed.

Further, with the configuration of the removing roller and the cleaning blade 48, the toner and the carrier accumulated on the blade at the contact portion are removed by the blade 48, and then the blade 48 is removed.
(The solid content is generally high and the viscosity is high.) However, the moving member applies a shearing force to the vicinity of the deposited toner to prevent the toner from being deposited.

Therefore, in this embodiment, surplus fog toner and carrier on the photosensitive drum 1 are removed by a removing roller, and the toner and developer are collected by a cleaning blade, and the collected toner moves as it is. Therefore, a shearing force is positively applied to the removed developer by a conveying means such as a screw to convey the developer to a developer adjusting means (not shown). Since the removed developer cannot be reused (recycled) in the developing device as it is because the solid content concentration has changed or the dispersion state has changed, the removed developer is transferred to a portion having a developer adjusting means to adjust the developer. Is used again in the developing step as a developer.

The cleaning blade is biased so that the cleaning blade and the holding member are electrically floated from the main body so as to have the same potential as the removal bias. By doing so, stable bias application becomes possible, and problems due to discharge to other parts can be prevented.

When the member constituting the cleaning blade is a resistor having a resistance of 10 ¹² Ωcm or more,
Although cleaning with a blade is possible, at this time, there is a problem that the cleaning blade is charged by friction. Therefore, the bias potential applied to the removing roller may be affected by the frictional charging.
In addition, even if it is not directly affected, there are also safety problems such as electric noise being generated by discharging the triboelectrically charged electric charges to other portions, and discharging to an operator. The cleaning blade is in contact with the removal roller to prevent the bias from leaking.
It is necessary to electrically float the main body including the holding member and to ground the main body.

[0085]

According to the present invention described above, the following effects can be obtained.

According to the present invention, in the conventional method of simultaneously performing the development and the removal of the excess toner in the background portion by the developer carrier, the latent image carrier and the developer carrier are required to secure a relatively long development time. The size (hereinafter, referred to as “development nip width”) of the nip portion formed in the direction of movement of the developer carrier surface is increased. In particular, in the case where at least one of the latent image carrier and the developer carrier has elasticity and the developer carrier is brought into contact with the latent image carrier to form a nip portion, the developing nip is preferably used. The contact pressure tends to increase in order to increase the width. In the liquid developing device according to the second aspect, since the removal roller is provided, it is not necessary to completely remove the excess toner by the developer carrier, and the development time can be further shortened. The development nip width can be made smaller. Thereby, the contact pressure of the developer carrier with respect to the latent image carrier can be further reduced. Further, by forming the nip portion by bringing the removing roller into contact with the latent image carrier, more time can be secured for removing the surplus toner with the removing roller, and the surplus toner can be more reliably removed. We were able to.

According to the first to eighteenth aspects of the present invention, the removal roller can reliably remove excess toner remaining on the latent image carrier after development, so that image fogging can be prevented. There is an excellent effect that a high quality image can be formed. In addition, since the removal roller is provided, it is not necessary to completely remove the excess toner from the developer carrier, so that the charging potential of the latent image carrier can be reduced. This also has an excellent effect that the durability of each roller can be improved. In addition, the removal roller can remove a part of the surplus carrier on the latent image carrier after the development, and has an excellent effect that the consumption of the carrier can be reduced.

In the liquid developing device according to the first aspect, the latent image formed on the latent image carrier is developed by the liquid developer carried on the developer carrier. After this development,
Even when the toner adheres to a background portion (non-image portion) on the latent image carrier and surplus toner remains, the surplus toner and the carrier liquid can be removed by the removal roller. Thereby, fogging of the image due to the excess toner can be prevented, and consumption of the carrier liquid can be reduced.

According to a second aspect of the present invention, in the liquid developing apparatus of the first aspect, the nip forming means forms a nip by means of a pressing force control means for applying pressure to the latent image carrier of the removing roller. Fluctuation could be prevented.

In the pressing force control means of the liquid developing apparatus according to the third aspect, the pressing force can be adjusted and the nip can be adjusted.

The liquid developing apparatus according to claim 4, wherein the removing voltage applying means to the removing roller comprises a conductive urging member, and the urging member applies the removing voltage when the urging member comes into contact with the removing roller. Was completed.

In the removing voltage applying means of the liquid developing apparatus according to the fifth aspect, the removing voltage applying means has a conductive surface on a contact surface with the removing roller so that a contact portion between the removing roller and the removing voltage applying means is always worn. By providing the wear member, it was possible to prevent poor contact caused by dirt on the contact surface.

In the removing voltage applying means of the liquid developing apparatus according to the present invention, the removing voltage applying means to the removing roller applies the removing voltage by contacting the core of the removing roller, thereby stably removing the removing voltage. Could be applied.

9. The liquid developing device according to claim 7, wherein said rotating means is provided with a latent image carrier end gear at an end of the latent image carrier, and an end of said removing roller is engaged with said latent image carrier end gear. The removal roller end gear was arranged in the section, and the removal roller could be rotated.

According to the eighth aspect of the present invention, an image with less image unevenness can be obtained by making the surface moving speed of the developer carrier substantially equal to the surface moving speed of the latent image carrier.

In one embodiment of the present invention, a one-way clutch is provided at the end gear of the removing roller to reduce the surface moving speed of the developer carrier and the surface moving speed of the latent image carrier. The speed difference was corrected, and image unevenness was prevented.

In the liquid developing device according to the tenth aspect, when the removing roller is separated from the latent image carrier by the displacement device, the contact roller is brought into contact with the latent image carrier by the pressing force control means. I was able to release.

According to the eleventh aspect of the present invention, in the liquid developing device, the contacting / separating means is a displacement device, and the removing device can be separated from the latent image carrier by rotating the cam with the displacement device having a cam shape.

In the liquid developing device according to the twelfth aspect, since the removing roller formed of the elastic body is constituted by a cored bar and a laminated structure of one or more layers, desired elasticity and electric resistance can be realized. Was.

In the liquid developing apparatus according to the thirteenth aspect, the removal roller formed of the elastic body has a volume resistance of 109 Ωcm.
By doing so, it was possible to apply a sweep voltage favorably, and it was possible to prevent an abnormal image without leaking the sweep voltage.

According to a fourteenth aspect of the present invention, the hardness of the removing roller formed of the elastic body is 50 degrees (JIS-JIS).
A) The following configuration prevented the occurrence of image deletion.

In the liquid developing apparatus according to the fifteenth aspect, the removal roller made of the elastic body can prevent the removal roller from being deteriorated without swelling or impregnating the carrier liquid of the developer.

In the liquid developing apparatus according to the present invention, the removal roller surface layer formed of the elastic body is a film layer having a thickness of 100 μm or less, thereby obtaining desired elasticity and preventing the removal roller from being deteriorated. Was prevented from adhering.

The liquid developing apparatus according to claim 17, wherein the removal roller surface layer formed of the elastic material has a volume resistance of 1
The invention according to claim 18, wherein the film layer having a thickness of 09 Ωcm or less can prevent a desired electric resistance value, deterioration of the removal roller, and adhesion of toner.
Alternatively, in the liquid developing device of 2, the voltage is applied to the developer carrier so as to generate an electric field between the image portion of the latent image and the developer carrier in a direction to move the toner toward the image portion. A developing voltage applying unit, and an electric field in a direction of pulling excess toner floating between the background portion of the latent image and the removal roller on the removal roller toward the removal roller,
Excess toner can be collected by providing a removing voltage applying unit that applies a voltage that generates an electric field that does not peel off the toner attached to the image portion.

In the liquid developing apparatus according to the eighteenth aspect, the toner is moved to the image portion side by the developing voltage applying means to develop the image portion. And
By the removal voltage applying means, the toner adhered to the image portion was not peeled off, but the excess toner floating on the background portion could be moved to the removal roller side and removed.

In general, in an electrophotographic developing device, the surface moving speed of the developer carrier is changed to the surface moving speed of the latent image carrier in order to send a sufficient amount of toner to an area opposite to the latent image carrier. It is set faster than that. For this reason, since the toner has a high moving speed with respect to the surface of the latent image carrier, a positional shift occurs between the toner and the latent image, and as a result, the leading end of the toner is blurred, or the balance between the vertical and horizontal lines is lost. A bad phenomenon appears. This phenomenon is also observed in liquid development. In the liquid developing device according to the nineteenth aspect, the surface of the developer carrier and the surface of the latent image carrier move at a substantially constant speed, and the speed of the latent image carrier in the tangential direction relative to the toner. Since no vector is provided, the above phenomenon did not occur.

According to a twentieth aspect of the present invention, there is provided a latent image carrier, a latent image forming means for forming a latent image on the latent image carrier, and a developing means for visualizing the latent image on the latent image carrier. And a transfer means for transferring a visible image on the latent image carrier to a transfer material, wherein the liquid developing device according to claim 1 is used as the developing means. Is what you do.

In the liquid image forming apparatus according to the twentieth aspect,
Since the excess developer on the latent image carrier after development is removed by the removal roller, the excess developer can be more reliably removed, and a high-quality image can be formed by preventing image fogging. Was completed.

In the liquid image forming apparatus according to the present invention, when the liquid developing device or the liquid image forming device is stopped, the removing roller is separated from the latent image carrier, thereby preventing permanent distortion of the removing roller. did it.

According to the twenty-second to twenty-ninth aspects of the present invention, the removal member can reliably remove excess toner remaining on the latent image carrier after development and carry the carrier, so that image fog can be reduced. Thus, a high-quality image can be formed while preventing the toner from being removed, and an excellent effect of collecting an extra carrier can be obtained. Further, since the removal member is provided, it is not necessary to completely remove the excess toner from the developer carrier, so that the charging potential of the latent image carrier can be reduced. This also has an excellent effect that the durability of each roller can be improved.

Further, there is an excellent effect that a part of the surplus carrier on the latent image carrier after the development can be removed by the removing member, and the consumption of the carrier can be reduced. In the wet developing device according to the first aspect,
A cleaning unit for cleaning the surface of the removing roller is provided to collect excess toner and carrier liquid.
At the time of recovery, if the contact position of the blade was high, toner adhered to the tip of the blade and did not flow down, but it could flow down by attaching the blade at least below the center position.

According to a twenty-third aspect of the present invention, in the liquid developing apparatus of the twenty-second aspect, the angle θ of the contact position of the cleaning blade with the removing roller is larger than the angle α formed by the tangential direction at the contact point of the blade and the blade. , The amount of toner remaining at the tip of the blade was reduced.

According to a twenty-fourth aspect of the present invention, in the liquid developing device of the twenty-second aspect, the hardness of the rubber member (for example, urethane) which is excellent in cleaning property and does not damage the surface of the removing roller for removing the excess toner is JISA. 50 degrees or more 80
Use below degree. Furthermore, by making the thickness of the tip portion thinner than the other portions, the cleaning property of the removing roller was excellent, and the toner at the tip portion of the blade did not stay, so that the blade could flow down smoothly.

According to a twenty-fifth aspect of the present invention, in the liquid developing apparatus of the twenty-second aspect, a sufficient rigidity can be obtained even when the liquid developing apparatus is thin by using a resin blade having higher rigidity than a rubber member. And excellent cleaning performance could be secured.

According to a twenty-sixth aspect of the present invention, in the liquid developing apparatus according to the twenty-second to twenty-fifth aspects, a rubber member that does not damage the surface of the developer support is replaced with a metal plate that can obtain a sufficient rigidity even if it is thin. Sufficient cleaning performance was secured by the adhered cleaning blade.

According to a twenty-seventh aspect of the present invention, in the liquid developing apparatus of the twenty-second to twenty-sixth aspects, the physical adhesion of the liquid developer to the blade surface is reduced by subjecting the back side of the cleaning blade to oil repellent treatment. As a result, the adhesion of the liquid developer could be prevented.

According to a twenty-eighth aspect of the present invention, in the liquid developing device of the twenty-second to twenty-seventh aspects, the recycling is facilitated by having a conveying means for moving the removed toner in the axial direction in the vicinity of the cleaning blade. .

According to a twenty-ninth aspect of the present invention, in the liquid developing device of the twenty-second to twenty-eighth aspects, the angle of the cleaning blade is in a minus direction with respect to the vertical and the moving blade is provided near the cleaning blade so that the cleaning blade stays on the blade. The toner could be collected without fail.

According to a thirtieth aspect of the present invention, in the liquid developing device according to the twenty-second to twenty-ninth aspects, a stable developing bias is applied by eliminating the influence of charging due to friction between a removing roller for removing excess toner and a cleaning member. Can be. In addition, the discharge due to the charged electric charge was eliminated, and the generation of electrical noise was prevented.

According to the invention of claim 31, in the liquid developing apparatus of claims 22 to 29, it is possible to eliminate the influence of electrification due to friction between the removing roller and the cleaning member and to apply a stable developing bias. In addition, the discharge due to the charged electric charge was eliminated, and the generation of electrical noise was prevented.

[Brief description of the drawings]

FIG. 1 is a sectional front view of a liquid image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional front view showing a main part of the apparatus shown in FIG. 1 in another state.

FIG. 3 is a plan view of the device shown in FIGS.

FIG. 4 is a bottom view of the device shown in FIGS.

FIG. 5 is an explanatory view of a sweep roller of the apparatus shown in FIGS.

FIG. 6 is an explanatory diagram showing a state in which a sweep roller is pressed against a photosensitive member by an abutting roller of the apparatus shown in FIGS.

FIG. 7 is an explanatory view showing a modified example of the sweep roller according to the present invention.

FIG. 8 is an explanatory diagram showing a state in which a sweep roller of the modification shown in FIG. 7 is pressed against a photosensitive member.

FIG. 9 is an explanatory diagram illustrating a state of a developer in a removal nip formed by a photoconductor and a developing roller.

FIG. 10 is an explanatory diagram illustrating a state of a developer in a removal nip formed by a photoconductor and a sweep roller.

FIG. 11 is an explanatory diagram of a cleaning unit of the apparatus shown in FIGS.

FIG. 12 is an explanatory view showing a modified example of the cleaning blade according to the present invention.

FIG. 13 is an explanatory view showing another modification of the cleaning blade according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Photoconductor drum 4 ... Developing device 40 ... Liquid developer 42 ... Developing roller 43 ... Removal roller 44 ... Coating member 48 ... Cleaning member 50 ... Cam 51 ... Cam follower

Continued on the front page (72) Inventor Mie Yoshino 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Noriyasu Takeuchi 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Toru Nakano 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Yusuke 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (Reference) 2H073 AA03 AA05 AA09 AA10 BA02 BA11 BA13 BA25 BA43 CA35 2H074 AA03 AA04 AA09 BB16 BB22 BB44 BB58 BB60 CC21 CC28 CC32 DD05 DD07 3J103 AA02 AA13 AA21 AA51 FA18 GA02 GA57 GA58 HA60 HA12 HA20

Claims (31)

[Claims] At least one developer carrier for carrying a high-viscosity, high-concentration liquid developer in which toner is dispersed in a carrier liquid, and an application member for applying the liquid developer to the developer carrier are provided. A liquid developing device for developing a latent image formed on the latent image carrier with the liquid developer carried by the developer carrier, wherein the latent image carrier surface movement direction downstream of the developer carrier And at least one removing roller formed of an elastic body for removing excess developer after development on the latent image carrier, forming a nip between the removing roller and the latent image carrier. A nip forming unit, a removing voltage applying unit that applies a voltage to the removing roller, a rotation driving unit that rotationally drives the removing roller, a contacting / separating unit that contacts and separates the removing roller and the latent image carrier, Clean the above removal roller And a cleaning unit for cleaning. 2. A liquid developing apparatus according to claim 1, wherein said nip forming means forms the nip by means of a pressing force control means for applying a pressure of said removing roller to said latent image carrier. 3. The liquid developing device according to claim 2, wherein the pressing force control means has a mechanism for adjusting the pressing force. 4. The liquid developing device according to claim 1, wherein the removing voltage applying means to the removing roller is constituted by a conductive urging member, and the urging member applies the removing voltage by contacting the removing roller. A liquid developing device comprising: 5. The liquid developing apparatus according to claim 4, wherein the removing voltage applying means has a conductive wear member on a contact surface with the removing roller so that a contact portion between the removing roller and the removing voltage applying means is always worn. A liquid developing device, comprising: 6. The liquid developing apparatus according to claim 4, wherein the removing voltage applying means for applying a removing voltage to the removing roller applies the removing voltage by contacting a core of the removing roller. 7. The liquid developing device according to claim 1, wherein the rotation drive means is provided with a latent image carrier end gear at an end of the latent image carrier, and is removed so as to mesh with the latent image carrier end gear. A liquid developing device, wherein a removing roller end gear is disposed at a roller end, and the removing roller end gear drives the removing roller to rotate. 8. The liquid developing device according to claim 7, wherein the rotational drive means causes the surface moving speed of the removing roller to be:
A liquid developing device, which is driven to rotate so as to be substantially equal to the surface moving speed of the latent image carrier. 9. The liquid developing device according to claim 7, wherein the rotation driving means includes a one-way clutch disposed on a removal roller end gear. 10. The liquid developing device according to claim 1, wherein the contacting / separating means is configured such that the removing roller is separated from the latent image carrier by a displacement device, and the removing roller contacts the latent image carrier by a pressing force control means. A liquid developing device comprising: 11. The liquid developing device according to claim 10, wherein the contacting / separating means has a cam as a displacement device, and the cam is rotated to separate the removing roller from the latent image carrier. Developing device. 12. The liquid developing device according to claim 1, wherein the removing roller is constituted by a cored bar and one or more laminated structures. 13. The liquid developing device according to claim 12, wherein the removing roller formed of an elastic body has a volume resistance of 10 ⁹ Ω.
cm or less. 14. The liquid developing device according to claim 12, wherein the hardness of the removing roller formed of an elastic body is 50 degrees (JIS).
-A) A liquid developing device characterized by the following. 15. The liquid developing device according to claim 12, wherein the removing roller formed of an elastic body swells in the carrier liquid of the developer and does not impregnate the carrier liquid. 16. The liquid developing apparatus according to claim 12, wherein the surface layer of the removing roller formed of an elastic body is a film layer of 100 μm or less. 17. The liquid developing device according to claim 12, wherein a volume resistance value of the removal roller surface layer formed of an elastic body is 1
A liquid developing device comprising a film layer having a thickness of not more than 0 ⁹ Ωcm. 18. The liquid developing device according to claim 1, wherein a voltage is generated between the image portion of the latent image on the developer carrier and an electric field in a direction for moving the toner toward the image portion side between the developer carrier and the developer. And an electric field in a direction of drawing excess toner floating between the background portion of the latent image and the removal roller on the removal roller toward the removal roller, and And a removing voltage applying means for applying a voltage that generates an electric field that does not peel off the toner attached to the portion. 19. The liquid developing device according to claim 1, wherein a surface moving speed of the developer carrier is substantially equal to the surface moving speed of the latent image carrier. 20. A latent image carrier, a latent image forming means for forming a latent image on the latent image carrier, a developing means for developing a latent image on the latent image carrier, and a latent image carrier 20. A liquid image forming apparatus comprising: a transfer unit for transferring a visible image on a body to a transfer material, wherein the developing unit is any one of claims 1 to 19.
A liquid image forming apparatus, comprising the liquid developing device according to any one of the preceding claims. 21. The liquid image forming apparatus according to claim 1, wherein the removing roller is separated from the latent image carrier when the liquid developing device or the liquid image forming device is stopped. Apparatus or liquid image forming apparatus. 22. At least one developer carrier for carrying a high-viscosity, high-concentration liquid developer in which toner is dispersed in a carrier liquid, and an application member for applying the liquid developer to the developer carrier. A liquid developing device for developing a latent image formed on the latent image carrier with the liquid developer carried on the developer carrier, wherein the developer carrier has a downstream surface moving direction of the latent image carrier. At least one removing member for removing the excess toner and carrier after development on the latent image carrier is provided on the side, and the removing member is provided with cleaning means for cleaning the surface with a roller, The liquid developing device, wherein the means is a blade member, and a contact position of the removing member with the roller is equal to or less than a vertical center position. 23. The liquid developing device according to claim 22, wherein
The cleaning blade contacts the removal roller at a position of an angle θ that forms a horizontal plane with the removal roller, and the cleaning blade contacts the removal roller at an angle α formed by the blade and a tangential direction at a contact point of the blade and the angle θ A liquid developing device, wherein the liquid developing device is arranged to be larger than the angle α. 24. The liquid developing device according to claim 22, wherein
A liquid developing device, wherein the hardness of the cleaning means is a rubber member having a hardness of 50 to 80 degrees according to JISA. 25. The liquid developing device according to claim 22, wherein
Cleaning means that the elastic constant of the material is 100 MPa or more, 50
A liquid developing device having a pressure of 00 MPa or less. 26. The liquid developing device according to claim 22, wherein
A liquid developing apparatus, wherein the cleaning means includes a blade having a configuration in which an elastic body having a hardness of 50 to 80 degrees is adhered to a thin plate of a rigidity providing member. 27. The liquid developing device according to claim 22, wherein
A liquid developing device, wherein a cleaning member is subjected to an oil-repellent treatment. 28. The liquid developing device according to claim 22, further comprising a transporting means for moving the removed toner in an axial direction in a vicinity of the cleaning blade. Liquid developing device. 29. The liquid developing device according to claim 22, wherein the angle of the cleaning blade is in a minus direction with respect to the vertical, and a moving member is provided near the cleaning blade. Liquid developing device. 30. The liquid developing device according to claim 22, wherein the cleaning blade and a holding portion thereof are electrically floating from the apparatus main body,
In addition, a bias is applied so that the potential is substantially the same as that of the developer carrier. 31. The liquid developing device according to claim 22, wherein when the electric resistance of the material of the cleaning blade is 10 ¹² Ωcm or more, the cleaning blade and its holding portion are electrically connected to the apparatus main body. A liquid developing device, wherein the liquid developing device is floating and this portion is grounded.