JP2002287513A - Liquid developer coating method and device, developing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid developer coating method and a device therefor by which the life of a developing roller or a developing belt functioning as the developer carrier of a developing device is prolonged, and the developing device equipped with the coating device and an image forming apparatus equipped with the developing device. SOLUTION: The surface of the developing roller 402 is coated with liquid developer with which the surface of a coating roller 404 is coated via an intermediate roller 405. Thus, the rollers 402 and 404 do not directly come into contact with each other, so that the surface of the roller 402 is not worn and damaged by a recessed part 404a on the surface of the roller 404, and mechanical stress applied to the roller 402 is reduced and the life of the roller 402 is prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an application member which rotates while applying a predetermined amount of liquid developer on the surface thereof. A method and an apparatus for applying a liquid developer to be applied to the surface of a member to be applied, and an electrostatic latent image formed on an image carrier is applied to the developer carrier as the member to be applied by the applying member. The present invention relates to a developing device that visualizes an image with a liquid developer obtained, and an image forming apparatus such as a copying machine, a facsimile, and a printer using the developing device.

[0002]

2. Description of the Related Art Using a high-viscosity, high-concentration liquid developer,
2. Description of the Related Art An image forming apparatus for visualizing an electrostatic latent image formed on a surface of an image carrier is known (for example, Japanese Patent Application Laid-Open No. Hei 7-1522).
No. 54, JP-A-7-209922, JP-A-7-209922
No. 219355). In this type of image forming apparatus, first, the surface of a photoconductor as an image carrier is uniformly charged by a charging unit. Next, the surface of the photoconductor is exposed by an optical writing unit according to the image data to form an electrostatic latent image on the surface of the photoconductor. Then, the electrostatic latent image formed on the surface of the photoreceptor is developed by a developing device into a visible image.

The above-mentioned developing device is a liquid developer for applying a liquid developer stored in a storage tank to a surface of a developer carrier including a developing roller and a developing belt in a uniform thickness in a thin layer. A coating device is provided. The developer carrier is disposed in close proximity to the surface of the photoconductor. Then, in a developing region which is a portion close to the developer carrier and the photoconductor, the liquid developer applied to the surface of the developer carrier by the coating device comes into contact with the surface of the photoconductor. Thus, the electrostatic latent image on the photoconductor is visualized by the toner in the liquid developer thin layer, and a toner image is formed on the photoconductor. The liquid developer remaining on the developer carrier after passing through the developing area is removed by a cleaning member such as a blade and collected in a storage tank.

[0004] The toner image formed on the photosensitive member in this manner is transferred onto a transfer material such as transfer paper or an OHP sheet. Thereafter, the toner image is fixed on the transfer material by a fixing device, so that an image is formed on the transfer material. When the toner image is transferred to the transfer material, the toner remaining on the photoconductor is removed by a photoconductor cleaning unit.

[0005] The liquid developer is obtained by dispersing a solid consisting of a resin and a pigment in a carrier liquid which is an insulating liquid, for example, in a developing solution solvent consisting of an insulating liquid such as dimethylpolysiloxane oil. 50 to 10,000 mPa · S in which toner as visualized particles is dispersed at a high concentration
Is used. When the liquid developer comes into contact with the surface of the photoconductor, the charged toner in the liquid developer moves in the insulating liquid by electrostatic force, and the electrostatic latent image on the photoconductor is developed. I do. Therefore, as the liquid developer, the shorter the moving distance of the toner, the higher the developing efficiency. Therefore, it is desirable to form a micron-thick layer of liquid developer on the developer carrier, and contact the thinned liquid developer with the photoconductor to develop the electrostatic latent image. . This is especially true for 50-
This is more remarkable when a high-viscosity liquid developer of 10,000 mPa · S is used.

As described above, when the electrostatic latent image is developed with a thin layer of the liquid developer, the density is determined by the thickness of the thin layer. Therefore, in the developing device, it is important to form a uniform thin layer of the liquid developer on the developer carrier. Therefore, in this type of developing device, as a coating member for applying the liquid developer on the developer carrier, for example, Japanese Patent Application Laid-Open No. H11-2651
As shown in Japanese Patent Application Publication No. 22, a liquid developer coating apparatus having an application roller (anilox roller) having a regular concave portion formed on the surface is used. That is, in this coating apparatus, first, the liquid developer is carried on the surface of the coating roller. The surplus liquid developer carried on the surface of the application roller contacts the surface of the application roller to serve as an application amount regulating member that regulates the application amount of the liquid developer carried on the surface of the application roller. Is removed by a doctor blade. Thereby, the amount of the liquid developer carried on the surface of the application roller is measured. The liquid developer measured in this manner is directly transferred onto the developer carrier to form a uniform liquid developer thin layer of the liquid developer on the developer carrier of the developing device. Will be done.

[0007]

However, the above-described conventional liquid developer application device is configured to directly transfer and apply the liquid developer onto a developer carrier of the developing device by using the application roller. . For this reason, in a developing device using this coating device, the contact rotation between the coating roller and the developer carrier causes regular engraving of the surface of the coating roller to form the developer carrier. The surface is easily shaved, and the developer carrier is significantly worn and damaged.

Accordingly, a developing roller or a developing belt as a developer carrier in a developing device using this type of coating device is of low hardness which can form a predetermined developing nip by contact with the photosensitive member. That. At least the surface is made of a conductive material capable of applying a bias. At least the surface has high mechanical strength with high abrasion resistance due to rubbing with the application roller. At least the surface has high mechanical strength with high abrasion resistance due to rubbing with the cleaning blade. It should have smoothness so that the liquid developer can be uniformly applied to the photoreceptor. Such characteristics are required.

As described above, in a developing apparatus using this type of coating apparatus, the specifications required for the developing roller and the developing belt as the developer carrier are strict. Is narrow, and it is difficult to produce a highly durable developer carrier. In particular, among the above-mentioned required characteristics for the developer carrying member, the item indicated by で relates to the durability of the material of the developer carrying member, and determines the life of the developer carrying member. However, in the conventional developer carrier, for example, even when the surface of the developing roller is coated with a conductive PFA tube, the durability life thereof is about 50,000 sheets.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a liquid developer capable of extending the life of a developing roller or a developing belt as a developer carrying member of a developing device. It is an object of the present invention to provide a method and an application device for applying an agent, a developing device provided with the applying device, and an image forming apparatus provided with the developing device.

[0011]

In order to achieve the above object, an object of the present invention is to provide a method in which a predetermined amount of liquid developer is carried on a surface of a coating member and the coating member rotates. In the method of applying a liquid developer, in which the carried liquid developer is applied to the surface of a member to be coated on which the liquid developer is applied, the surface of the member to be applied is brought into contact with the surface of the member to be applied. Moves in the same direction and at the same speed as the surface of the member to be applied, and contacts the surface of the member to be coated, and the contact surface with the surface of the member to be coated moves in the opposite direction to the surface of the member to be coated. Applying the liquid developer carried on the surface of the application member to the surface of the intermediate application member, and applying the liquid developer applied to the surface of the intermediate application member to the surface of the member to be applied. It is a feature.

In the method of applying a liquid developer, for example, a predetermined amount of the liquid developer is carried on the surface of the application roller by rotating an application roller (or an application belt) as the application member. The liquid developer carried on the surface of the application roller contacts the surface of the application roller, and the contact surface with the surface of the application roller moves in the same direction and at the same speed as the surface of the application roller. It is applied to the surface of an intermediate roller (may be an intermediate belt) as a member. The liquid developer applied to the surface of the intermediate roller is applied, for example, to the surface of a developing roller or a developing belt as the member to be applied. Here, the intermediate roller is
The contact surface with the surface of the developing roller or the developing belt moves in a direction opposite to the surface of the developing roller or the developing belt. Thus, in this application method, the liquid developer carried on the surface of the application roller is applied to the developing roller and the like via the intermediate roller. Therefore, since the coating roller does not directly contact the developing roller and the like,
The wear and damage of the developing roller and the like due to the contact rotation between the coating roller and the developing roller and the like can be avoided.

According to a second aspect of the present invention, there is provided an application member which carries a predetermined amount of liquid developer on the surface and rotates, and a contact surface of the application member which is in contact with the surface of the application member and which is in contact with the surface of the application member. Moves in the same direction and at the same speed as the surface of the member to be coated, and contacts the surface of the member to be coated on which the liquid developer is applied, so that the contact surface with the surface of the member to be coated is opposite to the surface of the member to be coated. And an intermediate coating member that moves in the direction.

In this liquid developer application device, the liquid developer carried on the surface of an application roller, an application belt or the like as the application member passes through an intermediate roller or an intermediate belt as the intermediate application member. Is applied to a developing roller or the like as the member to be applied. Therefore, since the coating member does not directly contact the coating member, wear and damage of the coating member due to the contact rotation between the coating member and the coating member is avoided.

According to a third aspect of the present invention, in the liquid developer applying apparatus of the second aspect, an application roller as the application member having a concave portion having a uniform pattern formed on a surface thereof, and an abutting surface of the application roller. And a coating amount regulating member for regulating an application amount of the liquid developer carried on the surface of the application roller.

In this liquid developer applying apparatus, the liquid developer applied to the surface of the application roller is applied by the coating amount regulating member and the engraving of a uniform pattern applied to the surface of the application roller. The amount is regulated. As a result, the measured predetermined amount of the liquid developer is applied to the surface of the application roller.

According to a fourth aspect of the present invention, in the liquid developer applying apparatus according to the third aspect, the intermediate coating member also serves as the coating amount regulating member.

In this liquid developer coating apparatus, since the intermediate coating member also serves as the coating amount regulating member, it is necessary to arrange a coating amount regulating member such as a doctor blade or the like in contact with the coating member. Disappears. Accordingly, the layout around the application member can be made compact, and the size of the application device can be reduced.

According to a fifth aspect of the present invention, in the liquid developer coating apparatus of the fourth aspect, the intermediate coating member has a hardness of JI.
SA is an intermediate roller having an elastic layer of 30 degrees or more and 70 degrees or less.

In the liquid developer coating device, the intermediate coating member has the elastic layer. Thus, for example, the intermediate roller as the intermediate coating member uniformly contacts the coating roller as the coating member in the axial direction. Further, the contact pressure of the intermediate roller with respect to the application roller is maintained at a value equal to or higher than a certain value. Therefore, the intermediate roller can sufficiently exhibit the function as the coating amount regulating member.

According to a sixth aspect of the present invention, in the liquid developer applying apparatus of the fourth or fifth aspect, the intermediate coating member has a smooth layer made of a low-friction member on the surface. Things.

In this liquid developer coating device, since the intermediate coating member is provided with a lubricating layer made of a low friction member on the surface thereof, for example, the developing roller as the member to be coated and the intermediate coating member The frictional force generated at the contact portion with the intermediate roller is reduced. As a result, the load on the drive system of the developing roller and the intermediate roller and the mechanical stress applied to the intermediate roller and the developing roller are reduced, and the components of the coating apparatus have a long life.

The invention of claim 7 is the invention of claims 2, 3, 4, 5
Or the speed changing means for changing the rotation speed of the coating member and the intermediate coating member while maintaining the rotation speed of the coating member and the intermediate coating member at a constant speed. It is characterized by having.

In this liquid developer coating apparatus, the speed changing means keeps the rotation speed of the coating member and the intermediate coating member constant while maintaining the rotation speed between the coating member and the intermediate coating member. The rotation speed is changed. This allows
The application amount of the liquid developer applied to the member to be applied can be changed by the intermediate application member. Therefore, for example, by using this coating device as a coating device that applies a liquid developer to a developing roller of a developing device of an image forming apparatus, the image density of a toner image developed by the developing device can be adjusted. Will be possible.

The invention of claim 8 is the invention of claims 2, 3, 4,
In the liquid developer application device of 5, 6, or 7, the application member and the intermediate application member are driven by a single drive source.

In this liquid developer coating device, since the coating member and the intermediate coating member are driven by a single drive source, the peripheral speed at the contact surface between the coating member and the intermediate coating member is controlled. The difference can be eliminated. This eliminates abrasion of the contact surface between the application member and the intermediate application member due to sliding friction, and extends the life of the application member and the intermediate application member.

The ninth aspect of the present invention is the second aspect of the present invention.
In the apparatus for applying a liquid developer according to any one of 5, 6, 7 and 8, the coating member and the coating member are so arranged that the relationship between the surface speed Va of the coating member and the surface speed Vm of the intermediate coating member is Va <Vm. A driving unit for forcibly driving the intermediate coating member, and
The drive transmission means for transmitting the drive of the drive means to the coating member has a one-way rotation mechanism that allows the coating member to freely rotate in the forward direction.

In this liquid developer coating device, the driving means rotates the intermediate coating member at a higher surface speed than the coating member. The one-way rotating mechanism allows the coating member to freely rotate in the forward direction. Accordingly, in a state where the contact surface between the application member and the intermediate application member is not slipping, the application member comes into contact with the intermediate application member and is driven to rotate. Then, when slippage occurs on the contact surface between the application member and the intermediate application member, the driving member forcibly drives the application member, and the slippage on the contact surface is eliminated. Accordingly, it is possible to eliminate a variation in the application amount of the liquid developer due to the sliding of the contact surface between the application member and the intermediate application member, and a difference in the peripheral speed at the contact surface between the application member and the intermediate application member. Further, wear due to rubbing of the contact surface between the coating member and the intermediate coating member is eliminated,
The life of the coating member and the intermediate coating member is extended.

The invention according to claim 10 is the invention according to claims 2, 3, 4,
In the liquid developer applying apparatus of 5, 6, 7, 8 or 9, the position of a tangent line between the intermediate roller as the intermediate applying member and the member to be applied is set at the rotation center line of the applying roller as the applying member. And a plane including the rotation center line of the intermediate roller and an intersection line with the surface of the intermediate roller, and provided at a position including the intersection line on the upstream side in the rotation direction of the intermediate roller. It is assumed that.

In this liquid developer coating apparatus, the intermediate roller is sandwiched between the developing roller and the coating roller by the rotation of the developing roller and the coating roller. The force starts to work. Accordingly, the intermediate roller surely comes into contact with the developing roller and the application roller, and stable application of the liquid developer is performed on the developing roller.

The invention of claim 11 is the invention of claims 2, 3, 4,
5, 6, 7, 8, 9 or 10, wherein the width of the intermediate coating member is smaller than the width of the coating member.

In this liquid developer coating device, an excessive amount of the liquid developer squeezed out by the contact between the coating member and the intermediate coating member adheres to the end of the surface of the intermediate coating member. Is gone. Therefore, when a cleaning member for cleaning the surface is placed in contact with the surface of the intermediate coating member, the load on the cleaning member is reduced. Further, when an excessive amount of the liquid developer adheres to the end of the surface of the intermediate coating member, there is a problem that the liquid developer is scattered and the inside of the apparatus is contaminated or wasted, In the liquid developer coating device, such a problem is solved.

The twelfth aspect of the present invention is the second aspect of the present invention.
5, 6, 7, 8, 9, 10 or 11, wherein the width of the intermediate coating member is larger than the width of the member to be coated.

According to the eleventh aspect of the present invention, there is provided an apparatus for applying a liquid developer.
As described above, by making the width of the intermediate coating member smaller than the width of the coating member, the excess amount of the liquid developer squeezed out by the contact between the coating member and the intermediate coating member is reduced. The adhesion of the surface of the intermediate coating member to the end is avoided. However, with such a configuration, an excessive amount of the liquid developer squeezed out by the contact between the application member and the intermediate application member adheres to the end surface of the intermediate application member. Then, when an excessive amount of liquid developer attached to the end surface of the intermediate application member is applied to, for example, a developing roller as the member to be applied, which comes into contact with the intermediate application member,
The image developed by the developing roller is adversely affected.
Therefore, in the liquid developer coating device, the width of the intermediate coating member is made larger than the width of the member to be coated. Thus, an excessive amount of the liquid developer adhering to the end face of the intermediate coating member does not adhere to the end of the surface of the member to be applied. Therefore, when the member to be coated is the developing roller, the image developed by the developing roller is not adversely affected. Further, the load on the cleaning member for cleaning the surface of the developing roller is reduced. Further, the problem that the liquid developer is scattered from the developing roller and the inside of the apparatus is contaminated or wasted is eliminated.

The invention of claim 13 is the invention of claims 2, 3, 4,
In the liquid developer coating apparatus of 5, 6, 7, 8, 9, 10, 11 or 12, the adhering substance adhering to the surface of the intermediate coating member is removed by contacting the surface of the intermediate coating member. A cleaning member that performs cleaning.

In the liquid developer coating device, the cleaning member removes the deposits on the surface of the intermediate coating member. Therefore, for example, when this coating device is used as a coating device of a developing device in an image forming apparatus, after the electrostatic latent image on the image carrier is developed by the developing device, it remains on the intermediate coating member. The liquid developer whose concentration has not been adjusted is not used again for development as it is. This makes it possible to eliminate the ghost that occurs when the liquid developer whose concentration has not been adjusted is reused as it is.

According to a fourteenth aspect of the present invention, in the liquid developer coating device of the thirteenth aspect, a width of a portion of the cleaning member that contacts the surface of the intermediate coating member is larger than a width of the coating member. It is a feature.

In the liquid developer coating device, the cleaning member removes the adhered substance from the surface of the intermediate coating member more reliably. Therefore, the liquid developer of which concentration has not been adjusted remaining on the surface of the intermediate coating member is not used again for development as it is, and the concentration unevenness of the liquid developer thin layer applied on the member to be coated is prevented. Is prevented. Further, the surface of the intermediate application member is not damaged by the end of the cleaning means, and the life of the intermediate application member can be extended.

According to a fifteenth aspect of the present invention,
5, 6, 7, 8, 9, 10, 11, 12, 13, or 14
In the liquid developer applying apparatus, the surface of the applying member except for both ends of the applying member is uniformly engraved.

In this liquid developer coating device, since the non-engraving areas are provided at both ends of the coating member, the liquid developer coating area and the non-coating area are formed on the surface of the intermediate coating member. Can be formed. This makes it possible to prevent an excessive amount of the liquid developer from adhering to both ends of the surface of the member to be coated, which is in contact with the non-coating region on the surface of the intermediate coating member. Therefore,
For example, it is possible to reduce the adverse effect on the toner image on the photoconductor due to the excessive adhesion of the liquid developer to the developing roller and the increase in the load on the cleaning means of the photoconductor and the developing roller.

According to a sixteenth aspect of the present invention, in the liquid developer coating device of the fifteenth aspect, the width of the engraving applied to the surface of the coating member is smaller than the width of the intermediate coating member. Is what you do.

In this liquid developer coating device, the width of the engraving applied to the surface of the coating member is smaller than the width of the intermediate coating member. In addition, it is possible to reliably form the non-application region where the liquid developer is not applied. Accordingly, excessive application of the liquid developer to the member to be applied due to excessive adhesion of the liquid developer to the intermediate application member, and an increase in the load on the cleaning unit contacting the intermediate application member can be reduced. .

The invention of claim 17 is the invention of claim 15 or 16
Wherein the width of the engraving applied to the surface of the coating member is smaller than the width of the member to be coated.

In this liquid developer coating device, the width of the engraving applied to the surface of the coating member is smaller than the width of the member to be coated. In addition, it is possible to surely form the non-application region where the liquid developer is not applied. Thus, an excessive amount of the liquid developer can be prevented from adhering to both ends of the surface of the member to be coated. It is possible to reduce adverse effects and an increase in the load on the cleaning means for the photoconductor and the developing roller.

According to the eighteenth aspect of the present invention, the electrostatic latent image formed on the surface of the image carrier can be more easily developed than the liquid developer applied to the surface of the developer carrier which moves in contact with the surface of the image carrier. In the developing device for visualization, as a liquid developer coating device for coating the liquid developer on the surface of the developer carrier,
Claims 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
The present invention is characterized in that 12, 13, 14, 15, 16, or 17 liquid developer application devices are used.

In this developing device, the liquid developer is applied to the developer carrier, which is the member to be coated of the liquid developer applying device, by an intermediate applying member of the liquid developer applying device. Is done. Therefore, the developer carrier does not come into direct contact with the liquid developer application member, and the life of the components of the developer carrier can be extended.

According to a nineteenth aspect, in the developing device according to the eighteenth aspect, the relationship between the peripheral speed Vm of the intermediate coating member and the moving speed Vd of the surface of the developer carrier is Vd <Vm <.
2.times.Vd.

In this developing device, the peripheral speed Vm of the intermediate coating member and the moving speed Vd of the surface of the developer carrier are determined.
Is Vd <Vm <2 × Vd, image density fluctuations due to environmental fluctuations and the like are prevented, and an image with a stable density can always be developed.

According to a twentieth aspect of the present invention, there is provided an image bearing member, image forming means for forming an electrostatic latent image on the surface of the image bearing member, and a static image formed on the surface of the image bearing member by the image forming means. 20. An image forming apparatus comprising: a developing device for visualizing an electrostatic latent image with a liquid developer; wherein the developing device is used as the developing device.
Wherein the developing device is used.

In this image forming apparatus, the developing device according to claim 18 or 19 is used as a developing device for visualizing an electrostatic latent image formed on the surface of the image carrier with a liquid developer. Therefore, it is possible to prevent image density fluctuation due to environmental fluctuation or the like, and to always obtain an image having a stable density density.

According to a twenty-first aspect of the present invention, in the image forming apparatus of the twentieth aspect, a photosensitive member having a surface layer made of amorphous silicon is used as the image carrier.

In this image forming apparatus, the surface layer of the photoreceptor is formed of amorphous silicon. Thereby, the durability of the surface of the photoreceptor is improved, and stable image formation is performed.

The invention of claim 22 is the invention of claim 20 or 21
A pattern image forming means for forming a pattern image in a non-image area on the image carrier, a density detecting means for detecting an image density of the pattern image, and the pattern detected by the density detecting means. Developer application amount control means for controlling the application amount of the liquid developer applied to the surface of the developer carrier by changing the moving speed of the application member and the intermediate application member according to the image density of an image. It is characterized by having.

In this image forming apparatus, the moving speed of the coating member and the intermediate coating member is changed by the developer coating amount control means in accordance with the image density of the pattern image detected by the density detection means. . Therefore,
The liquid developer can be applied to the developer carrying member, which is a member to be coated, at an appropriate speed ratio by the intermediate coating member. That is, the amount of the liquid developer applied to the surface of the developer carrier can be controlled. This makes it possible to apply the liquid developer uniformly and with little variation to the developer carrier. Also,
The image density formed on the image carrier can be adjusted and changed according to the operator's preference.

[0055]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter, referred to as a copying machine) which is a liquid developed image forming apparatus will be described below. Figure 1
1 is a schematic configuration diagram of a copying machine according to the present embodiment. This copying machine includes a photoreceptor 1 as an image carrier, and is configured around the photoreceptor 1 by a charger 2, an exposure device 3, a developing device 4, a transfer device 5, a photoreceptor cleaning device 6, and the like. Image forming means is provided. As the material of the photoreceptor 1, a-Si, OPC, or the like can be used. The charger 2 may be in the form of a roller, a charger, or the like. Further, as the exposure apparatus 3, LE
D or a laser scanning optical system can be used.

A case where an image is formed by reversal development using the copying machine having the above configuration will be described. In FIG.
The photoreceptor 1 is driven to rotate in a direction indicated by an arrow at a constant speed during image formation by a driving unit such as a motor (not shown). Then, first, the surface of the photoconductor 1 is uniformly charged in the dark by the charger 2. Next, the exposure device 3 irradiates and forms a light image of the original on the surface of the photoconductor 1. As a result, an electrostatic latent image is formed on the surface of the photoconductor 1. Thereafter, when the electrostatic latent image passes through the development area A, the electrostatic latent image is visualized (developed) by the developing device 4, and a toner image is formed on the surface of the photoconductor 1. You. The toner image is transferred to the transfer device 5 in the transfer area B.
Is primarily transferred onto an intermediate transfer member (belt) 502 of the transfer device 5 by a transfer bias applied through the transfer roller 501 of the transfer device 5. The toner image primarily transferred onto the intermediate transfer body 502 is secondarily transferred onto a transfer material such as copy paper or an OHP sheet by a secondary transfer unit (not shown) in a secondary transfer area (not shown). Then, the transfer material on which the toner image has been secondarily transferred is fixed to the toner image by a fixing device (not shown), and then discharged out of the apparatus as a copy print.

On the other hand, after the primary transfer, the residual potential remaining on the photosensitive member 1 is removed by the charge removing lamp 7.
After the primary transfer, the residual toner remaining on the photoreceptor 1 is removed by the photoreceptor cleaning device 6 to prepare for the next image formation. In addition, as the transfer device 5, for example, a method using corona discharge, an adhesive transfer method, a thermal transfer method, or the like other than the method using the illustrated electrostatic roller 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.

In the copying machine according to the present embodiment, as a developer for developing the electrostatic latent image on the photoreceptor 1, low viscosity using Isopar (Exxon ™), which is conventionally and generally used, is used as a carrier. (About 1 cSt), low-concentration (about 1%) liquid developer, but high-viscosity, high-concentration liquid developer is used. As the range of the viscosity and the concentration of the developer, for example, the viscosity is 50 to 10000 mPa ·
It is preferable to use S having a concentration of 5% to 40%. As the carrier liquid, those having high insulation properties such as silicone oil, normal paraffin, IsoparM (Exxon trademark), vegetable oil, and mineral oil can be used. Further, as the liquid developer, according to the purpose,
A volatile or non-volatile substance can be selected and used. Further, the particle diameter of the toner of the liquid developer 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 copying machine according to the present embodiment will be described. This developing device 4
As shown in FIG. 1, a developing roller 402 rotatably disposed in a developer storage tank 401 for storing a liquid developer D therein, and a sweep roller 403 rotatably disposed in a casing 410. It has. Further, the developing device 4 includes the developing roller 402 as a member to be coated.
Is provided with an application device for applying the liquid developer D to the liquid developer. The coating device includes an application roller 404 having a uniform engraving pattern on the surface as an application member, an intermediate roller 405 as an intermediate application member for applying the liquid developer D to the developing roller 402, and a liquid developer D. It mainly comprises a stirring / transport screw 406 as a stirring / transporting means. The developing roller 402 and the sweep roller 403 have cleaning members 407 and 40 made of a metal blade or a rubber blade, respectively.
8 are provided. The cleaning members 407, 4
08 may be a roller type instead of a blade type.

In the coating apparatus, the intermediate roller 405 contacts the surface of the coating roller 404 to remove excess liquid developer on the surface, and
4 also serves as a doctor roller for regulating the amount of developer carried on the surface. And this intermediate roller 4
The liquid developer applied to the application roller 404 and measured by a doctor blade 409 serving as an application amount regulating member is transferred to the surface of the application roller 05.

As shown in FIG. 2, the intermediate roller 405 is provided with an elastic layer 405b made of an elastic material on an outer peripheral surface of a cored bar 405a, and a lubricating layer 405c on an outer peripheral surface of the elastic layer 405b. The configuration is provided. As a material of the elastic layer 405b of the intermediate roller 405,
Urethane rubber can be used. The elastic layer 4
The material of 05b is not limited to the urethane rubber, and may be any material that does not swell or dissolve in the carrier liquid or developer.

On the other hand, as shown in FIG. 3, the developing roller 402 and the sweep roller 403 are
Elastic layers 402b and 40 made of an elastic material on the outer peripheral surface
3b, and conductive layers 402c and 403c are provided on the outer peripheral surfaces of the elastic layers 402b and 403b. Thus, urethane rubber can be used as a material of the elastic layers 402b and 403b. The developing roller 402 and the sweep roller 403 are
In order to efficiently form a development nip and a removal nip with the photoconductor 1, the elastic layer 402b,
The rubber hardness of 403b is desirably 50 degrees or less in JIS-A hardness.

The materials of the elastic layers 402b and 403b of the developing roller 402 and the sweep roller 403 are as follows.
The material is not limited to the urethane rubber, and may be any material that does not swell or dissolve in the carrier liquid or developer. Further, the developing roller 402 and the sweep roller 40
3 is a material whose surface is conductive and does not swell or dissolve in the carrier liquid / developer. The material of each of the elastic layers 402b and 403b as long as it has elasticity is not limited by the above-described conductivity and swelling and dissolving. Here, when each of the elastic layers 402b and 403b is an insulator, the developing bias voltage and the sweep bias voltage are applied to the developing roller 502 and the sweep roller 5 respectively.
It is necessary to apply the voltage not from each of the cores 502a and 503a, but from their surfaces.

Another method for efficiently forming a developing nip and a removing nip between the developing roller 402 and the sweep roller 403 and the photosensitive member 1 is as follows. An elastic layer may be formed on the photoconductor 1 side. Further, as another method for giving elasticity to the photoconductor 1 side, the photoconductor 1 may be configured by an endless belt member. The developing roller 402 and the sweep roller 403 are coated or coated with a tube so that their surfaces have a smoothness of Rz 3 μm or less.

In FIG. 1, when the developing roller 402 and the sweep roller 403 are brought into contact with the photoreceptor 1 at an appropriate pressure, respectively, the elastic layers 502b and 503b of the developing roller 402 and the sweep roller 403 become elastic. As a result, a development nip and a removal nip are formed between the photoconductor 1 and the photoconductor 1. In particular, by forming the developing nip, a certain developing time is ensured for the toner in the liquid developer to move and adhere to the photoconductor 1 by the developing electric field in the developing area A. become. Further, the developing roller 402 and the sweep roller 403 and the photosensitive member 1
By adjusting the contact pressure with the nip, it is possible to adjust the nip width, which is the width of each nip in the surface movement direction. These nip widths are set to be larger than the product of the linear velocity of the developing roller 402 and the sweep roller 403 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, the required minimum nip width is 3 mm and the process speed is 300 mm / s
If ec, the development time constant is 10 msec.

During the operation of the developing device 4, a thin developer layer composed of a liquid developer is formed on the surface of the developing roller 402 by the application roller 404 of the application device and the intermediate roller 405. At this time, the thickness of the liquid developer applied on the developing roller 402 was set such that the pigment content in the toner carried per 1 cm ² of the surface of the developing roller 402 was 3 μg or more and 60 μg or less. . Therefore, 3 to 3
A thin layer of developer having a thickness of 10 μm was applied. The reason for this is that if the thickness of the liquid developer applied to the surface of the developing roller 402 is such that the pigment content in the toner carried per 1 cm ^{2 of the} developing roller surface is smaller than 3 μg, it is not sufficient. This is because the amount of the pigment does not move to the image area formed on the photoreceptor 1, and the image density of the image area may be reduced. Further, the developing roller 402
In the case where the pigment content in the toner carried per 1 cm ² of the surface of the photosensitive member 1 is larger than 60 μg, the background portion of the photosensitive member 1 after developing the electrostatic latent image formed on the photosensitive member 1 This is because there is a possibility that the excess toner remaining in the cleaning roller 403 will increase, and the removal of the excess toner by the sweep roller 403 will be incomplete.

When the developer thin layer formed on the surface of the developing roller 402 passes through the developing nip formed by the photosensitive member 1 and the developing roller 402, the developer thin layer Contact Thereby, the toner in the developer thin layer moves to the electrostatic latent image (image portion) formed on the surface of the photoreceptor 1, and the electrostatic latent image is developed.
That is, in the image portion of the photoreceptor 1, the toner moves to the photoreceptor 1 side, and in the background portion (non-image portion) of the photoreceptor 1,
The toner is moved to the surface of the developing roller 402 by the electric field formed by the developing bias potential and the photoconductor potential, so that the toner does not adhere to the background portion of the photoconductor 1.

Here, if a part of the toner adhering to the background portion of the photosensitive member 1 does not move to the surface of the developing roller 402 and remains on the photosensitive member 1, the toner formed on the photosensitive member 1 becomes an image. Fog occurs. The sweep roller 403 is provided to sweep (clean) toner that causes fogging of the image (hereinafter, referred to as “fogging toner”). The sweep roller 403 is, as shown in FIG.
The toner image (developer layer) developed on the photoreceptor 1 by the developing roller 402 is provided at a position downstream of the photoreceptor 02 so as to be pressed against the photoreceptor 1. Then, the surface of the sweep roller 403 moves in contact with the surface of the photoconductor 1 at a substantially constant speed, so that the fog toner on the background of the photoconductor 1 is removed.

The residual toner remaining on the surface of the developing roller 402 after the development of the electrostatic latent image is removed from the cleaning member 407 made of a blade to prevent ghost.
To be removed. Here, the residual toner remaining on the surface of the developing roller 402 is, for example, as shown in FIG.
The toner may be removed by the surface of the intermediate roller 405 that rotates in contact with the surface of the developing roller 402 in the opposite direction. 4, the residual toner removed from the surface of the developing roller 402 by the intermediate roller 405 adheres to the surface of the intermediate roller 405. The residual toner adhering to the surface of the intermediate roller 405 is removed by a cleaning member 41 including a blade disposed in contact with the intermediate roller 405.
1 removes from the surface of the intermediate roller 405. In addition, the liquid developer removed by the sweep roller 403 is removed by the cleaning member 408 including a blade in order to maintain the sweep (cleaning) performance of the sweep roller 403.

In this way, the rollers 402, 4
The liquid developer removed from 03, 404, and 405 is collected in a temporary storage section 412 provided adjacent to the developer storage tank 401. The liquid developer collected in the temporary storage unit 412 is transferred by the transfer screw 413.
The developer is sent to a density adjusting section (not shown), and the developer density is adjusted in the density adjusting section.
Returned to 1 and reused. In the temporary storage unit 412,
A stirrer 413, a concentration detector (not shown), a liquid amount detector (not shown), and the like are provided.
2, the concentration and the amount of the liquid developer collected in the liquid developer 2 are detected. On the basis of this detection result, replenishment of a new liquid developer and replenishment of a carrier are performed in the concentration adjusting section, and the concentration of the collected liquid developer is adjusted to be uniform.
Here, the supply amount of the liquid developer into the developer storage tank 401 is set to be slightly larger than the consumption amount of the liquid developer. Thereby, the developer storage tank 4
The liquid developer overflowing from 01 is returned into the temporary storage section 412. Thus, the liquid developer is always circulated.

In the developing device having the above-described structure, the density of the image formed on the photosensitive member 1 is
It is determined by the thickness of the liquid developer (developer thin layer) applied to the surface of the developing roller 402. Therefore, in the developing device according to the present embodiment, as the application roller 404 of the application device, for example, an anilox roller having a concave portion 404a having a uniform pattern formed on its surface as shown in FIG. 5 is used. . Since such anilox rollers are used for gravure printing, they are also called gravure rollers. The shape of the concave portion 404a on the surface of the application roller 404 is, for example, a diagonal line type as shown in FIG. 6A, a pyramid type as shown in FIG. 6B, or a lattice type as shown in FIG. And so on. In the coating apparatus according to the present embodiment, the coating roller 404 in which the diagonal recess 404a is formed is used for reasons such as good transferability. Thus, the application roller 404
By using the anilox roller as described above, the excess amount of the liquid developer carried on the surface thereof is squeezed and dropped at a contact portion with the intermediate roller 405 also serving as the coating amount regulating member, whereby the coating roller A predetermined amount of the liquid developer accurately measured by the concave portion 404a is carried on the surface of the 404.

The liquid developer accurately measured and carried on the surface of the application roller 404 composed of the anilox roller is transferred to the surface of the developing roller 402 via the intermediate roller 405. On the developing roller 402, a uniform thin layer made of a predetermined amount of liquid developer is formed. Here, the intermediate roller 405 rotates so as to be equal to the peripheral speed of the application roller 404 and move in the same direction at the contact portion with the application roller 404, and at the contact portion with the developing roller 402. The developing roller 402 rotates in a reverse direction opposite to the rotating direction.
Thus, a thin layer of the liquid developer having a uniform thickness is formed on the surface of the developing roller 402.

That is, the thin layer of the liquid developer immediately after the transfer from the application roller 404 to the intermediate roller 405 has a shape in which the pattern of the concave portion 404a on the surface of the application roller 404 is directly transferred. Therefore, at a contact portion between the intermediate roller 405 and the developing roller 402, the intermediate roller 405 is rotated in a reverse direction opposite to the rotation direction of the developing roller 402. As a result, due to the linear velocity difference between the intermediate roller 405 and the developing roller 402, the developer thin layer transferred to the surface of the developing roller 402 is stretched so as to be even, and is uniformly spread on the surface of the developing roller 402. A developer thin film having an appropriate thickness is formed.

The application roller 404 having a concave portion 404a formed on the surface thereof, such as the anilox roller, is brought into direct contact with the developing roller 402, and the liquid developer applied on the surface of the application roller 404 is removed. When the coating is performed on the surface of the developing roller 402, the surface of the developing roller 402 is worn by being rubbed by the concave portion 404 a on the surface of the applying roller 404. And will be damaged. That is, in the case of such a configuration, the developing roller 402
The surface of the application roller 404 and the surface of the application roller 404 move in directions different from each other, so that the surface of the application roller 404 always comes into contact with the concave portion 404a of the surface of the application roller 404 with a large linear velocity difference.
As a result, the surface of the developing roller 402 is damaged by the friction due to the difference in linear speed. Therefore, in the coating apparatus having such a configuration, there is a problem that the life of the developing roller 402 is significantly shortened.

On the other hand, in the coating apparatus according to the present embodiment, as described above, the liquid developer applied to the surface of the application roller 404 is applied to the developing roller 402 via the intermediate roller 405. It is configured to be applied to a surface. As a result, the developing roller 402 and the application roller 404 do not come into direct contact with each other, and the surface of the development roller 402 is
04a eliminates wear and tear. The intermediate roller 405 contacts the developing roller 402 while rotating in the reverse direction. However, since the surface of the intermediate roller 405 has no irregularities, the surface of the developing roller 402 may not be damaged. Absent. Therefore,
In the coating apparatus according to the present embodiment, the developing roller 402
The mechanical stress applied to the developing roller 402 is reduced, and the life of the developing roller 402 can be extended.

The intermediate roller 405 of the coating apparatus according to the present embodiment is in contact with the coating roller 404. Therefore, there is no peripheral speed difference at the contact portion with the application roller 404. Therefore, the mechanical stress applied to the intermediate roller 405 from the application roller 404 is small, and the surface of the intermediate roller 405 is not worn or damaged by the concave portion 404a on the surface of the application roller 404.

As described above, the application roller 404 composed of the anilox roller is used, and the application amount regulating member is brought into contact with the application roller 404 to apply the liquid developer carried on the surface of the application roller 404. In an application device configured to measure the amount, generally, as the application amount regulating member,
Doctor blade 40 such as a coating device according to the present embodiment
9 or a doctor roller. Here, the doctor blade 409 is used as a coating amount regulating member.
In the case of a coating device using a varnish, since the configuration is relatively simple, it is suitable for downsizing the coating device. However, in this case, the contact portion of the doctor blade 409 with the application roller 404 is likely to be worn. In addition, the doctor blade 4
There is a problem in that foreign matter mixed in the liquid developer is clogged between the surface of the application roller 404 and the surface of the application roller 404, causing uneven application of the thin developer layer applied to the surface of the application roller 404.

On the other hand, as the coating amount regulating member,
In the case of the coating device using the doctor roller, the doctor roller has less wear and the clogging of foreign matter mixed in the liquid developer is less, which is advantageous compared to the case where the doctor blade is used. Become. However, when a doctor roller is used as the application amount regulating member, there is a problem that the application apparatus itself becomes large.

Therefore, in the coating apparatus according to the present embodiment, the intermediate roller 405 may be configured to also serve as the doctor roller. That is, the surface of the intermediate roller 405 is brought into contact with the surface of the application roller 404 at a pressure sufficient to measure and apply an appropriate amount of liquid developer to the surface of the application roller 404. Thus, the intermediate roller 405 can function as the doctor roller.

FIG. 4 shows an example of a copying machine equipped with a coating device having a configuration in which the intermediate roller 405 also serves as the doctor roller. In the coating apparatus of this copying machine, the doctor blade 409 of the coating apparatus shown in FIG. 1 is not required. In the coating apparatus shown in FIG. 4, the space for disposing the doctor blade 409 which is no longer needed is used, and the foreign matter removing blade 414 is disposed in this space. The purpose of this foreign matter removing blade 414 is to remove foreign matter in the liquid developer adhering to the surface of the application roller 404. It is in contact with the surface of the roller 404.

Therefore, in this coating apparatus, the foreign matter mixed in the liquid developer is removed by the foreign matter removing blade 41.
4 and the surface of the application roller 404 are not clogged, and the surface of the application roller 404 is uniformly coated with the liquid developer. The foreign matter is leveled at the nip between the intermediate roller 405 and the application roller 404, which are arranged downstream of the foreign matter removal blade 414 in the rotation direction of the application roller 404, and the influence thereof is eliminated. Is done. In this way, by providing the intermediate roller 405 with the function as the doctor roller, it is possible to provide a small coating apparatus with less coating unevenness.

In the coating apparatus shown in FIG. 4, the cleaning member 4
07 (see FIG. 1), the cleaning member 411 is arranged in contact with the intermediate roller 405.
Thereby, the developing roller 4 after the development of the electrostatic latent image is formed.
The residual developer remaining on the surface of the intermediate roller 405 moves to the surface of the intermediate roller 405 which comes into contact with the developing roller 402, and is cleaned. Then, the residual developer that has moved to the surface of the intermediate roller 405 is removed from the surface of the intermediate roller 405 by the cleaning member 411 disposed in contact with the intermediate roller 405. As described above, by eliminating the cleaning member 407 in contact with the developing roller 402, the surface of the developing roller 402 is not worn or damaged by the rubbing of the cleaning member 407, and the life of the developing roller 402 can be extended. .

It is desirable that the surface of the intermediate roller 405 be uniformly contacted with the surface of the coating roller 404 along the rotation axis direction of the coating roller 404. Therefore, the intermediate roller 405 needs to have the elastic layer 405b as described above. In order for the intermediate roller 405 to have the function as the application amount regulating member, the intermediate roller 405
However, it is necessary to contact the application roller 404 with a certain pressure or more. That is, in the coating apparatus according to the present embodiment, the amount of the liquid developer applied to the coating roller 404 is determined by the volume of the concave portion 403a of the coating roller 404. Accordingly, if the contact pressure of the intermediate roller 405 as the coating amount regulating member with respect to the coating roller 404 is insufficient, the concave portion 404a of the coating roller 404
In some cases, the liquid developer may pass between the other surface and the surface of the intermediate roller 405.

Therefore, as described above, when the contact pressure of the intermediate roller 405 with respect to the coating roller 404 is insufficient, the amount of the liquid developer applied to the coating roller 404 is reduced. The application amount is not determined by the volume of the concave portion 404a of the 404, and an image having an appropriate density cannot be formed. The amount of the liquid developer passing between the surface of the application roller 404 other than the concave portion 404a and the surface of the intermediate roller 405 depends on the linear velocity of the intermediate roller 405 and the application roller 404, the viscosity of the liquid developer, and the like. It also changes by. For example, the higher the viscosity of the liquid developer, the more noticeable the passage of the liquid developer. Therefore, for example, when the viscosity of the liquid developer changes due to a change in the temperature of the image forming environment, the amount of the liquid developer applied to the application roller 404 varies, and becomes unstable.

Therefore, in the coating apparatus according to the present embodiment, the contact pressure of the intermediate roller 405 with respect to the coating roller 404 is set to 0.2 MPa, and the contact pressure of the intermediate roller 405 with respect to the coating roller 404 is sufficiently increased. The intermediate roller 405 is provided with a function as a regulating member (doctor roller) for efficiently regulating the amount of the developer applied to the application roller 404.

It is desirable that the application roller 404 and the intermediate roller 405 are ideally rollers having a perfect circular cross section and no rotational fluctuation. However, the mechanical accuracy of such rollers is limited. Therefore, in the intermediate roller 405 in the coating apparatus of the present embodiment, the above-described rotational runout is absorbed by the elastic layer 405b (see FIG. 2), and the outer peripheral surface of the intermediate roller 405 is brought into contact with the outer peripheral surface of the coating roller 404. The contact is always stable.

The rubber hardness of the elastic layer 405b of the intermediate roller 405 is desirably 70 degrees or less in JIS-A hardness. That is, the elastic layer 4 of the intermediate roller 405
If the rubber hardness of 05b is greater than 70 degrees, it is difficult to make the surface of the intermediate roller 405 uniformly contact the surface of the application roller 404. Here, if the surface of the intermediate roller 405 is forcibly brought into contact with the surface of the application roller 404, the energy required for deformation of the elastic layer 405b increases, so the core metal of the intermediate roller 405 that receives this load 405a must be thicker and stronger than necessary. The intermediate roller 4
In the case where the rubber hardness of the elastic layer 405b of No. 05 is as low as 30 degrees or less, it is difficult to obtain the contact pressure necessary for giving the intermediate roller 405 a function as the coating amount regulating member, The elastic layer 405 of the intermediate roller 405
b needs to be greatly deformed.
There is a problem that the life of the 05 is shortened.

Therefore, in the coating apparatus according to the present embodiment, the rubber hardness of the elastic layer 405b of the intermediate roller 405 is set to 40 degrees in JIS-A hardness. As the elastic layer 405b of the intermediate roller 405, a rubber material such as the urethane rubber can be used. However, since this kind of rubber material generally has a large friction coefficient, an extremely large frictional resistance is generated at a contact portion between the elastic layer 405b and the developing roller 402 as the member to be coated. Such frictional resistance not only increases the load on the drive system of the intermediate roller 405 and the developing roller 402 but also increases the load on the intermediate roller 405 and the developing roller 4.
02 is significantly reduced.

Therefore, in the coating apparatus according to the present embodiment, as shown in FIG. 2, a lubricating layer 405c made of a low friction member is provided on the surface of the intermediate roller 405. The lubricating layer 405c is made of, for example, PTFE, PFA,
A fluororesin such as PVDF or PVF is applied to the elastic layer 40.
5b, or by coating a tube made of these resins. Specifically, as the intermediate roller 405, the elastic layer 405b
The outer peripheral surface of which was covered with a 50 μm-thick PFA tube. Similarly, the developing roller 402 used was one covered with a conductive PFA tube having a thickness of 50 μm.

A continuous copy test was performed using the copying machine shown in FIG. 4 using the liquid developer coating apparatus having the above-described configuration. As a result, even when the copying of 200,000 sheets of plain paper was completed, the machine described above was used. No image deterioration due to the damage of the developing roller 402 caused by mechanical stress was found, and it was found that sufficient durability quality was obtained. In addition, by using a photoreceptor whose surface is formed of amorphous silicon (a-Si) as the photoreceptor 1 of the copying machine, the photoreceptor 1 exhibits mechanical strength superior to that of an organic photoreceptor (OPC). Its life could be extended.

In this type of coating apparatus,
As described above, the application amount of the liquid developer to the developing roller 402 is determined by the cell volume (cell volume capacity per unit area) of the concave portion 404 a formed on the surface of the application roller 404 and the application amount of the liquid developer. It is determined by the dislocation rate of the liquid developer to the developing roller 402. Therefore, in the copying machine according to the present embodiment, in order to obtain a toner image having a target image density on the photoreceptor 1, an anilox roller having an appropriate cell volume is selected, and the intermediate roller 405 is pressed with a sufficient pressure. The contact is made so that the application amount of the liquid developer to the developing roller 402 does not change.

Therefore, the transfer rate of the liquid developer from the coating roller 404 to the developing roller 402 shows a substantially constant value if the physical properties of the liquid developer are determined. However, when the viscosity or the like of the liquid developer changes due to a change in environmental temperature or the like, the above-described transition rate changes. For this reason,
When the dislocation rate changes due to environmental conditions or the like, when the electrostatic latent image formed on the photoconductor 1 is developed under the same developing conditions as the developing conditions before the change, the image of the developed toner image is obtained. The density will change.

Further, when the image density is controlled by controlling the developing electric field, there is no problem when the developing electric field is increased to output a high-density image. When an image is output, fine non-uniform unevenness occurs in the liquid developer layer after development. That is, since the behavior of the solid content of the liquid developer cannot be controlled under a low electric field, when the surface of the photosensitive member 1 and the surface of the developing roller 402 separate and the liquid developer separates, each surface becomes solid. These traces are attracted to each other, and the traces of the inquiries become fine non-uniform unevenness and remain in the liquid developer layer after development. As shown in the graph of FIG.
If the development rate is not 90% or more, it becomes conspicuous. For this reason, there is a limit in the density adjustment by such a developing electric field, and there is a problem that it is impossible to cope with a large change in the coating amount such that the developing rate exceeds 10%.

Further, the amount of liquid developer required to obtain a toner image having an appropriate density varies depending on the smoothness of a toner image transfer surface of a transfer material onto which the toner image is transferred. For example, compared to a transfer material having a toner image transfer surface having a high degree of smoothness such as coated paper, plain paper having a low smoothness of the toner image transfer surface has an extra amount for filling the unevenness of the toner image transfer surface. There is a problem that a liquid developer is required.

In order to solve such a problem, the driving system of the coating roller 404 and the intermediate roller 405 of the coating apparatus according to the present embodiment includes the coating roller 404 and the intermediate roller 405 rotating at the same speed. A speed changing unit 415 for changing the rotation speed of the application roller 404 and the intermediate roller 405 while maintaining the relationship is provided (see FIG. 9). That is, in this coating apparatus, the relative movement speed between the surface of the intermediate roller 405 and the surface of the developing roller 402 is changed by changing the rotation speed of the coating roller 404 and the intermediate roller 405 by the speed changing unit 415. Can be changed. Here, the application amount of the liquid developer applied onto the developing roller 402 by the intermediate roller 405 is proportional to the roller speed ratio between the developing roller 402 and the intermediate roller 405 as shown in the graph of FIG. And change almost linearly. Therefore, in this coating apparatus, the speed changing means 415 changes the rotation speeds of the coating roller 404 and the intermediate roller 405 to change the roller speed ratio between the developing roller 402 and the intermediate roller 405. The developing roller 40
2 can adjust the amount of the liquid developer to be applied.

The drive system of the application roller 404 and the intermediate roller 405 is, for example, as shown in FIG.
6, the application roller 404 and the intermediate roller 405
Is a motor 4 such as a servo motor or a stepping motor.
17. The motor 417 is accompanied by a driver 418. This driver 41
8 is a controller 4 according to the characteristics of the motor 417.
19 receives a frequency signal and an A / D signal generated by
The motor 417 can be rotated at a rotation speed according to the D signal. Then, the operation unit 420 and the control board 421
The controller 419 issues an appropriate signal in response to a request from the controller 404 to control the rotation speeds of the intermediate roller 405 and the application roller 404. Thus, the linear velocity ratio of the intermediate roller 405 and the application roller 404 to the development roller 402 is changed, and the application amount of the liquid developer applied on the development roller 402 is adjusted.

The amount of liquid developer applied onto the developing roller 402 can be controlled by changing the peripheral speed of the intermediate roller 405 with respect to the developing roller 402. However, if only the peripheral speed of the intermediate roller 405 is changed, a peripheral speed difference occurs between the application roller 404 and the intermediate roller 405. When such a peripheral speed difference occurs, the surface of the intermediate roller 405 is damaged by the concave portion 404a on the surface of the application roller 404, and the life of the intermediate roller is shortened. Therefore, the intermediate roller 405 and the application roller 404 are unlikely to generate a peripheral speed difference as much as possible at the contact portion between them.
Desirable for the lifetime of

Therefore, in the coating apparatus according to the present embodiment,
With the peripheral speed between the application roller 404 and the intermediate roller 405 kept constant, the speed ratio between the developing roller 402 and the intermediate roller 405 is changed to change the developing roller 4.
The application amount of the liquid developer to the liquid developer 02 is controlled. In this case, it is desirable that the application roller 404 and the intermediate roller 405 be driven by a single drive source. That is, when the application roller 404 and the intermediate roller 405 are driven by separate driving sources, respectively,
It is difficult to match the peripheral speeds of the intermediate roller 405 and the intermediate roller 405, and there is a possibility that a slight speed difference may occur between the application roller 404 and the intermediate roller 405.

As described above, with the peripheral speed of the coating roller 404 and the intermediate roller 405 kept constant,
FIG. 10 shows an example of a drive mechanism for driving the application roller 404 and the intermediate roller 405 by a single drive source. The drive mechanism shown in FIG. 10 is driven by a single motor 417.
The intermediate roller 405 is configured to be rotationally driven in a direction indicated by an arrow via a drive transmission unit 416. In FIG. 10, when the intermediate roller 405 is driven to rotate, the application roller 404 is driven to rotate in the direction of the arrow by the frictional force generated at the contact portion between the intermediate roller 405 and the application roller 404. Thus, the intermediate roller 405 and the application roller 404 are driven without generating a speed difference between the application roller 404 and the intermediate roller 405.

Here, the application roller 404 and the intermediate roller 4
In order to eliminate the peripheral speed difference generated between the application roller 405 and the intermediate roller 405, the application roller 404 is driven, and the intermediate roller 405 is moved in the direction of the arrow by the frictional force generated at the contact portion between the application roller 404 and the intermediate roller 405. The drive mechanism may be configured to be driven to rotate. However, the intermediate roller 405
It is in contact with the developing roller 402 as a member to be coated with the liquid developer, and its surface is in contact with the surface of the developing roller 402 so as to move in a reverse direction (reverse direction). . For this reason, in the drive mechanism that drives the intermediate roller 405 to be driven by the drive rotation of the application roller 404, the load torque applied to the intermediate roller 405 by the reverse rotation of the developing roller 402 causes the intermediate roller 405 to rotate. The rotation becomes unstable. On the other hand, in the drive mechanism shown in FIG.
Without being affected by the rotational load of the intermediate roller 4
Since the intermediate roller 405 and the application roller 404 are driven by the driven rotation of the drive roller 05, the intermediate roller 405 and the application roller 404 are driven stably.

The liquid developer is composed of, for example, a high-concentration toner in which the toner as visualized particles is dispersed in a developing solution solvent composed of an insulating liquid such as dimethylpolysiloxane oil as described above. Have been. For this reason,
When the application roller 404 is rotated by the rotation of the intermediate roller 405 in a state where the liquid developer is applied to the surface of the application roller 404, the liquid developer functions as a lubricant, and There is a risk that the roller 404 may slip. In particular, when the intermediate roller 405 is driven and rotated at high speed, the slippage of the application roller causes
There is a high possibility that the amount of liquid developer applied to the intermediate roller 405 becomes unstable.

FIG. 11 shows the intermediate roller 405 as described above.
Of the application roller 404 and the intermediate roller 4
5 shows an example of a drive mechanism for driving the drive mechanism 05 with a single drive source. In this drive mechanism, not only the intermediate roller 405 but also the application roller 404 are forcibly driven by the drive transmission means 416 by the motor 417. However, the peripheral speed of the application roller 404 is set to be slightly lower than the peripheral speed of the intermediate roller 405. Specifically, the application roller 404 is driven at a peripheral speed that is delayed by about 2 to 5% with respect to the peripheral speed of the intermediate roller 405. In addition, a one-way clutch 423 as a one-way rotation mechanism that allows free rotation of the application roller 404 in the forward direction is provided in the drive system of the application roller 404 of the drive transmission unit 416. That is, the one-way clutch 423 transmits the rotation of the motor 417 in the direction of the arrow in FIG. 11 and forcibly drives the application roller 404 by the drive transmission unit 416.
The rotation of the motor 417 is not transmitted to the application roller 404 in the direction opposite to the direction of the arrow.

Therefore, in FIG.
7 rotates, first, the drive roller 416 forcibly drives the intermediate roller 405 in the direction of the arrow.
Then, when the application roller 404 does not slip, the driving force of the motor 417 is not transmitted to the application roller 404, and the application roller 404 is moved to the intermediate position as in the case of the drive mechanism shown in FIG. The roller 405 is driven and rotated at a constant speed by the rotation of the roller 405. That is, when the application roller 404 does not slip, the application roller 404 is not forcibly driven and the one-way clutch 42 is not driven.
By the action of No. 3, the idle rotation is performed, and the intermediate roller 405 is rotated. Therefore, in this state, the driving force for the application roller 404 does not act as a brake for the application roller 404.

On the other hand, when the application roller 404 is slipping, the application roller 404 is not driven to rotate by the intermediate roller 405, and
16, the forcible drive is performed in the direction of the arrow at a peripheral speed slightly lower than the peripheral speed of the intermediate roller 405. Therefore, in this driving mechanism, there is no variation in the amount of liquid developer applied due to the sliding of the application roller 404. The intermediate roller 40
The difference in peripheral speed between the roller 5 and the application roller 404 can also be reduced, and damage to the surface of the intermediate roller 405 due to the difference in peripheral speed can be eliminated.

By the way, in general, in a pair of rollers configured to move in the same direction on their contact surfaces, the amount of liquid passing between the rollers and the amount of liquid after the liquid has passed, Since the splitting ratio of the liquid on the rollers changes depending on the peripheral speed of each roller, the geometric shape of the peripheral surface, the material constant, the viscosity of the liquid, and the like, it is difficult to control the amount of liquid applied to each roller. That is, with such a pair of rollers,
It is known that when the applied liquid splits on each roller, a problem occurs that the applied liquid splits unevenly in a ring shape along the circumferential direction of each roller.

Therefore, in a developing device in which a thin layer of liquid developer is formed on the developing roller 402 as a developer carrying member by using the above-described liquid developer applying device, the intermediate roller 405 of the applying device is used. It is desirable to drive the developing roller 402 such that the direction of movement on the contact surface is opposite. Thus, the intermediate roller 405 is connected to the developing roller 40.
By driving such that the moving direction on the contact surface is opposite to the direction of 2, the above-described problem can be solved.

However, in the coating apparatus according to the present embodiment, an anilox roller having a concave portion 404a formed on the surface is used as the coating roller 404. Therefore, the liquid developer layer applied (transferred) from the application roller 404 onto the intermediate roller 405 has the pattern of the concave portion 404a. Therefore, if the peripheral speed Vm of the intermediate roller 405 and the peripheral speed Vd of the developing roller 402 are equal to each other (Vm ≦ Vd), the pattern-shaped developer layer of the concave portion 404a becomes inconsistent with the intermediate roller 405. Developing roller 402
The transfer is directly performed on the developing roller 402 at a scale corresponding to the speed ratio of the developer, and a thin developer layer having a uniform layer thickness cannot be formed on the developing roller 402.

Therefore, in this coating apparatus, the peripheral speed Vm of the intermediate roller 405 is set to be higher than the peripheral speed Vd of the developing roller 402 (Vm> Vd), and
It is necessary to evenly spread the developer layer having the pattern shape of the concave portion 404a transferred to the above. The application amount of the liquid developer applied on the developing roller 402 changes almost linearly according to the speed ratio of Vm / Vd as shown in FIG.
When Vm> 2 × Vd, the transfer of the thin developer layer to the developing roller 402 becomes unstable, and the variation in the amount of application becomes large, which is not practically preferable.

Therefore, in a developing device using such a coating device, the peripheral speed Vm of the intermediate roller 405 is set to
With respect to the peripheral speed Vd of the developing roller 402, Vd <Vm <
The range is 2 × Vd or less. As a result, the pattern-shaped developer layer of the concave portion 404 a transferred to the developing roller 402 is spread evenly by the intermediate roller 405, and a thin developer layer having a uniform thickness is formed on the developing roller 402. Can be formed. Further, the transfer of the thin developer layer to the developing roller 402 is stabilized, and the variation in the application amount of the liquid developer applied on the developing roller 402 is eliminated.

As described above, in the developing device according to the present embodiment, the intermediate roller 405 of the application device contacts the application roller 404 in the forward direction and the application roller 404 in the reverse direction. It is spinning. Therefore, in this developing device, the coating roller 404 and the developing roller 402
Thus, the intermediate roller 405 is nipped and rotated. Accordingly, the application roller 404 and the development roller 402
In contrast, the intermediate roller 405 is located at a position downstream of the line connecting the rotation center of the coating roller 404 and the rotation center of the developing roller 402 in the rotation direction of the coating roller 404 and the developing roller 402. When in contact, the rotation of the application roller 404 and the development roller 402 exerts a force on the intermediate roller 405 to push it out from between the application roller 404 and the development roller 402. Therefore, in such a configuration, the intermediate roller 40
The contact between the developing roller 402 and the application roller 404 and the developing roller 402 becomes unstable, and there is a possibility that the liquid developer cannot be stably applied to the developing roller 402.

Therefore, in the developing device according to the present embodiment, as shown in FIG. 12, the rotation center of the coating roller 404 and the rotation center of the The intermediate roller 405 is configured to contact at a position upstream of the application roller 404 and the developing roller 402 in the rotation direction with respect to the line connecting the. That is, the position of the tangent line between the intermediate roller 405 and the developing roller 404 is defined by a plane including the rotation center line of the application roller 404 and the rotation center line of the intermediate roller 405,
It is provided at a position including the intersection line on the upstream side in the rotation direction of the intermediate roller 405 with respect to the intersection line with the surface of the intermediate roller 405. As a result, the rotation of the application roller 404 and the development roller 402 causes a force acting on the intermediate roller 405 to pinch the intermediate roller 405 between the application roller 404 and the development roller 402. Therefore, in this developing device, the intermediate roller 405 and the coating roller 4
Thus, the contact between the developing roller 402 and the developing roller 402 is stabilized, and the liquid developer can be stably applied to the developing roller 402.

By using the coating apparatus having the above-described configuration, for example, the temperature in the image forming apparatus changes, the viscosity of the liquid developer changes, and the liquid from the coating roller 404 to the intermediate roller 405 changes. When the transfer rate of the developer changes, the application amount itself of the liquid developer to the developing roller 402 changes, and when the application amount itself changes, or when the concentration of the liquid developer changes, It is possible to control such that the image density is kept constant by adjusting the application amount. In order to perform such control, it is necessary to detect a change in image density. As a detecting means for detecting a change in the image density, it is common practice to optically measure the image density using a sensor for detecting an optical signal.

Further, it is desirable that the portion where the image density is detected by the above-described sensor be a final image forming step as much as possible for the purpose of keeping the image quality constant. However, it is difficult to form a pattern image for image density detection on transfer paper after the transfer of the toner image, which is the final image forming step. Therefore, generally, the intermediate transfer member 502 or the photosensitive member 1
The pattern image is formed in the non-image area, and the image density of the pattern image is detected by the sensor (see FIG. 1). In this way, the image density that changes due to various factors is detected, and the developing roller 4 is changed according to the image density.
By controlling the amount of the liquid developer to be applied to the liquid crystal 02, the image quality can be made constant.

Here, if the only purpose is to keep the applied amount of the liquid developer on the developing roller 402 constant, the concentration of the developer applied on the developing roller 402 may be detected. Maintaining the image density of the toner image at a constant level includes factors such as development conditions and transfer conditions of the toner image. It is more effective to detect the image density with a density sensor.

FIG. 13 shows an example of a coating apparatus configured to keep the image density of the toner image constant using such a density sensor 424. In this coating apparatus, a non-image of the intermediate transfer member 502 or the photosensitive member 1 is detected by a density sensor 424 including a reflected light type optical sensor or the like disposed close to the intermediate transfer member 502 or the photosensitive member 1. The image density of the pattern image formed in the area is detected. This allows the operator to operate the operation unit 4
In addition to the image density information input at 20, the image density information detected by the density sensor 424 is transmitted to the control board 4.
21. In the control board 421, the operation unit 42
By comparing the image density information input at 0 with the image density information detected by the density sensor 424, it is determined whether to increase or decrease the amount of liquid developer applied to the developing roller 402. Then, the motor 4 of the coating device is
The rotation speed of the motor 417 is controlled by sending a signal to the controller 419 and the driver 418. Here, the image density information input by the operation unit 420 and the image density information detected by the density sensor 424 are compared to determine whether to increase or decrease the application amount of the liquid developer to the developing roller 402. However, this determination is made by storing appropriate density information set in advance in the storage device 42.
2, the density information stored in the storage device 422 may be compared with the image density information detected by the density sensor 424.

In the copying machine shown in FIGS. 1 and 4,
One developing device 4 is provided around the photoreceptor 1, and four developing devices are provided around the photoreceptor 1, and liquid developers of four colors of yellow, magenta, cyan, and black are provided. , A full-color image can be obtained by sequentially forming four color toner images on the photoreceptor 1 by each developing device. In this case, the properties of the liquid developers of the respective colors, for example, physical properties such as viscosity with respect to a temperature change, are different for the liquid developers of the respective colors. Therefore, in such a color copying machine, it is desirable to independently control the application amount of the liquid developer of each color applied to the developing roller of each developing device. Although an example of four full colors has been described here, the number of colors of an image can be variously set, such as two or five.

As described above, the application roller 40
By incorporating a liquid developer application device having a speed adjusting function of the intermediate roller 4 and the intermediate roller 405 into the image forming apparatus, it is possible to suppress fluctuations in the image density of the toner image and stabilize the image quality. Image formation can be performed with an optimal amount of liquid developer applied according to the type of transfer paper. Specifically, the operator inputs the type of transfer paper to be used on the operation unit 420, or determines the paper type of the transfer paper in the designated paper feed cassette. Then, according to the paper type, the control board 421 determines the number of rotations of the motor 417 for obtaining the optimum application amount for each paper type stored in the storage device 422 in advance. A signal corresponding to the determined rotation speed of the motor 417 is sent to the controller 419 and the driver 418 to control the rotation speed of the motor 417. As a result, a thin layer of the liquid developer having an optimum application amount according to the type of the transfer paper is formed on the developing roller 402.

The operating section 420 is provided with a function of selecting an image density according to the operator's preference. It is also possible to form it on the roller 402. As a result, in the color copying machine, it is possible to change the color tone of the color image according to the operator's preference without changing the image data itself.

On the other hand, in the coating apparatus according to the present embodiment, as shown in FIG. 14, the width of the coating roller 404 is formed larger than the width of the intermediate roller 405. That is, the surfaces of both ends of the application roller 404 are
05 so as not to be in contact with the surface. If this relationship is reversed as shown in FIGS. 15 (a) and (b),
Excess liquid developer squeezed out from between the application roller 404 and the intermediate roller 405 adheres to the intermediate roller 405. Then, the surplus liquid developer attached to the intermediate roller 405 is transmitted to the developing roller 402. As a result, the surplus liquid developer adheres to the photoreceptor 1, the transfer belt 502, and finally to the transfer paper, so that the image quality is reduced or the liquid developer is wasted.

Therefore, as shown in FIG. 14, by making the width of the application roller 404 larger than the width of the intermediate roller 405, the excess portion squeezed out from between the application roller 404 and the intermediate roller 405 is obtained. Liquid developer,
Since it adheres to the application roller 404 side, the intermediate roller 405
Only an appropriate amount of liquid developer that has passed through the contact portion between the application roller 404 and the intermediate roller 405 adheres to the upper portion. Therefore, extra liquid developer is prevented from adhering to the roller on the downstream side in the moving direction of the liquid developer, and it is possible to prevent deterioration of image quality and wasteful consumption of the liquid developer due to the extra liquid developer. Also, the intermediate roller 405 is
Since the elastic layer 405b is provided, the surface of the intermediate roller 405 is not damaged at the end of the application roller 404 made of a metal roller, and the life is prolonged.

In the developing device using the coating device, a thin layer of the liquid developer is formed on the developing roller 402 by the intermediate roller 405. When the width of 402 is large, the end of intermediate roller 405 contacts the surface of developing roller 402 as shown in FIG. Intermediate roller 405
A small amount of liquid developer squeezed out at the contact portion with the application roller 404 adheres to the side surface of the developing roller 402, and this is transferred to the developing roller 402.

The excess amount of the liquid developer adhering to the developing roller 402 as described above is spread in the axial direction at the contact portion with the photosensitive member 1. The liquid developer in the excessively applied area spread in a band shape cannot be controlled by the developing electric field, and adheres to the photoreceptor 1 side, causing fogging in a non-image area and density unevenness in an image area. And the image quality is significantly reduced. In order to prevent this, it is desirable that the width of the developing roller 402 be larger than the width of the photoconductor 1 so that the surface of the end of the developing roller 402 does not contact the photoconductor 1. However, in such a configuration, the developing roller 402 having the elastic layer 402b comes into contact with the end of the photoconductor 1 made of a highly rigid material,
The surface of the developing roller 402 is damaged.

Further, it is difficult to uniformly charge the entire area of the photosensitive member 1 in the width direction. Usually, there are uncharged or insufficiently charged regions at both ends of the photosensitive member 1.
In such a copying machine, the charged area and the effective image area are determined in consideration of this. On the other hand, if the developing roller 402 comes into contact with such a region where the charge is not sufficient, the liquid developer on the developing roller 402 adheres to the photosensitive member 1 without being controlled by the developing electric field. Therefore, the width of the developing roller 402 needs to be set shorter than the effective charging area on the photoconductor 1 and longer than the effective image area. In order to solve the above-described problems, in this coating apparatus, the length of the intermediate roller 405 is made longer than that of the developing roller 402 as shown in FIG.
In this manner, the liquid developer adhering to the side surface of the intermediate roller 405 can be prevented from adhering to the developing roller 402.

By the way, as described above, in the developing device in which a thin layer of the liquid developer is formed on the developing roller 402 and the electrostatic latent image on the photosensitive member 1 is developed, In many cases, unused liquid developer that has not contributed to the development remains. This unused liquid developer has a changed solid content concentration. That is, the solid portion of the liquid developer in the image portion corresponding to the electrostatic latent image adheres to the photoreceptor 1 and only the carrier portion remains on the developing roller 402. The liquid developer in the non-image area is
A part of the carrier adheres to the photoreceptor 1 side, and the solid content of the carrier substantially remains on the developing roller 1, leaving a high-concentration liquid developer.
When the liquid developer for the next development is applied to the developing roller 402 and developed while the liquid developer at the time of the previous development remains on the developing roller 402, the developing roller 402 A density difference occurs in the thin layer of the liquid developer applied on the substrate, and ghost of the image at the time of the previous development occurs.

Thus, in such a developing device,
The liquid developer used during the previous development is applied to the developing roller 402.
After removal from above, it is necessary to newly apply a liquid developer for developing the next electrostatic latent image and develop the next electrostatic latent image. As a method of removing the liquid developer used at the time of such previous development from the developing roller 402,
In general, for example, a method of cleaning the surface of the developing roller 402 by contacting a rubber or a blade obtained by bonding rubber and metal to the surface of the developing roller 402 is used.

Here, as described above, in the developing device according to the present embodiment, the intermediate roller 405 of the coating device is
The developing roller 402 is configured to contact the surface of the developing roller 402 so as to move in the opposite direction at the contact portion.
Therefore, in this developing device, the intermediate roller 40
5, the surface of the developing roller 402 can be cleaned, so that it is not necessary to arrange a new cleaning member in contact with the developing roller 402. As a result, the surface of the developing roller 402 is prevented from being damaged by being rubbed by the cleaning member, and the load at the time of driving the developing roller 402 is reduced.

On the other hand, after transferring the liquid developer applied on the intermediate roller 405 onto the developing roller 402,
When the untransferred liquid developer remaining on the intermediate roller 405 is left as it is, the untransferred liquid developer passes through the nip with the developing roller 402 and the developing roller 402
Again, causing the ghost. Therefore, in the developing device according to the present embodiment, as shown in FIG. 4, the cleaning member 411 is disposed in contact with the intermediate roller 405, and
The liquid developer remaining on the surface 5 is removed.
Specifically, a liquid blade remaining on the intermediate roller 405 is removed using a rubber blade as the cleaning member 411. This cleaning member 41
The liquid developer removed in step 1 is temporarily collected in the temporary storage unit 412 without being mixed with the liquid developer whose concentration has been adjusted in the developer storage tank 401 described above. Carried to
After the concentration is readjusted, the developer storage tank 401
Will be returned within. By providing the cleaning member 411 on the intermediate roller 405 in this manner, the developing roller 4
02 can be removed via the intermediate roller 405, and the occurrence of the ghost can be prevented.

The axial width of the cleaning member 411 disposed in contact with the intermediate roller 405 is as shown in FIG.
As shown in (a) and (b), it is desirable to make the width longer than the width of the developing roller 402 so that all the liquid developer remaining on the developing roller 402 after the development can be removed. . This is because the density of the liquid developer remaining on the developing roller 402 is unadjusted as described above, and if the liquid developer is reused as it is for development, image defects such as density unevenness may occur. It is. When the blade is used as the cleaning member 411, if the width of the blade is smaller than the width of the intermediate roller 405, stress concentration occurs on the surface of the intermediate roller 405 where the edge of the blade contacts. As a result, there is a high possibility that the surface of the intermediate roller 405 will be damaged. Therefore, in this case, it is desirable that the width of the cleaning member 411 be longer than the width of the intermediate roller 405 (FIG. 1).
7). Thus, by regulating the width of the cleaning member 411 of the intermediate roller 405, the unused liquid developer on the developing roller 402 is not used for development without adjusting the concentration.

In the above-described coating apparatus, as described above, as the coating roller 404, an anilox roller having a uniform pattern of concave portions 404a formed on the entire circumferential surface is used. By accurately measuring the amount of application, uniform application of the liquid developer to the application roller 404 is performed. However, as the application roller 404, it is also possible to use a roller having a smooth surface without the concave portion 404ad. Such a roller having a smooth surface is applied to the application roller 4.
When the roller 404 is used, the pressure at the contact portion with the intermediate roller 405, the geometric shape of the rollers 404, 405, the longitudinal elastic constant of the rollers 404, 405, the viscosity of the liquid developer, , 405 determines the amount of liquid developer passing between the rollers 404, 405, and the amount of liquid developer applied to the rollers 404, 405 according to the speed ratio of the rollers 404, 405. Is determined.

However, the contact pressure between the application roller 404 and the intermediate roller 405 should be made uniform in their axial directions due to problems such as mechanical dimensional accuracy and uniformity of material constants. Have difficulty. Therefore, the application amount of the liquid developer applied to the intermediate roller 405 from the application roller 404 varies due to the variation in the contact pressure between the application roller 404 and the intermediate roller 405.

On the other hand, in the coating apparatus according to the present embodiment, since the anilox roller is used as the coating roller 404, the liquid developing agent applied to the coating roller 404 is determined by the volume of the concave portion 404a. The application amount of the agent can be accurately measured. Here, high dimensional accuracy is required for the concave portion 404a on the surface of the application roller 404. Therefore, the concave portion 404a on the surface of the application roller 404 is manufactured by rolling. This rolling process can reproduce the shape of the die almost exactly,
It has the feature that it is work hardened by plastic deformation of the surface, and is superior to cutting. However, it is difficult to process a material having a high hardness, for example, a material having a hardness of 200 HV or more. Therefore, when processing requiring surface hardness is performed, hardness is increased by performing surface treatment such as hard chrome plating after rolling.

When the concave portion 404a is formed on the entire circumferential surface of the application roller 404, the liquid developer is applied on the entire surface of the intermediate roller.
Therefore, when the liquid developer applied on the intermediate roller 405 is applied on the developing roller 402, the width of the developing roller 402 is smaller than the width of the intermediate roller 405, as shown in FIG. Is also short, so that FIG.
As shown in FIG. 8, the surplus liquid developer that has been pushed outward in the axial direction by the contact pressure between the rollers 402 and 405 adheres to the end surface of the developing roller 402 in a small amount. The liquid developer adhered to the end surface of the developing roller 402 adheres to the photoconductor when the photoconductor 1 comes into contact with the liquid developer. Therefore, the liquid developer is transferred to the intermediate transfer member 502 and transferred to transfer paper. This increases the load on the cleaning unit. Here, as described above, the liquid developer is prevented from adhering to the intermediate transfer member 502 by setting the widths of the developing roller 402, the photosensitive member 1, the intermediate transfer member 502, and the like. However, there is a problem that the increase in the load on the photoconductor cleaning device 6 of the photoconductor 1 cannot be eliminated.

Therefore, in order to solve such a problem, in the coating apparatus according to the present embodiment, as shown in FIG. 19, the coating roller 404 does not have the concave portions 404a formed at both ends of the roller. Engraving area 404b
And an anilox roller having the recess 404a formed only on the entire circumferential surface at the center of the roller.
By using the application roller 404 having such a configuration, the liquid developer is hardly transferred to a portion of the intermediate roller 405 opposite to the non-engraving area 404b at both ends of the application roller 404. Then, the intermediate roller 405
A predetermined amount of the liquid developer is transferred only to the upper portion of the application roller 404 facing the application region where the central concave portion 404a is formed, and the application region is formed on the intermediate roller 405.

Here, as shown in FIG. 19, the width of the intermediate roller 405 is
By configuring the intermediate roller 404 to be longer than the width (application area) of the portion where a is formed, it is possible to form an area where the liquid developer is not applied on both ends of the surface of the intermediate roller 404. Further, the width of the developing roller 402 is made longer than the coating area which is the width of the concave portion 404a of the coating roller 404, and the end of the surface of the developing roller 402 is
By making contact with the non-coating areas at both ends of the intermediate roller 405, it is possible to eliminate the adhesion of the liquid developer to the end face of the developing roller 402 as described with reference to FIG. At this time, the concave portion 4 corresponding to the application region
The width of 04a needs to be set wider than the effective image area on the photoconductor 1. Further, the width of the effective charging area of the photoconductor 1 needs to be set to be slightly wider than this coating area. That is, if the width of the effective charging area is set too large, the surface of the developing roller 402 on which the liquid developer is not applied comes into contact with the surface of the photoconductor 1, and the developing electric field formed in the developing unit A May be unstable.

By using the liquid developer application device having such a configuration as an application device of an image forming apparatus, the application roller 404 and the intermediate roller 40 of the application apparatus can be used.
5 can prevent the liquid developer from being excessively applied at the contact portion and adhered to the end face. Thereby, stable image quality can be maintained, and the load on the cleaning unit of the photosensitive member 1 and the intermediate transfer member 502 can be reduced. Further, it is possible to prevent the inside of the apparatus from being contaminated due to the scattering of the excessively applied liquid developer, and to prevent unnecessary consumption of the liquid developer.

[0136]

According to the first to eighteenth aspects of the invention, it is possible to reduce the mechanical stress applied to the developing roller from the liquid developer applying device, and to prolong the life of the developing roller. Has an effect.

In particular, according to the third aspect of the present invention, the amount of the liquid developer can be accurately measured by the application roller and the application amount regulating member in contact with the application roller, so that a uniform amount of the application can be stably performed. Has an excellent effect.

According to the fourth aspect of the present invention, since the intermediate roller is also used as the coating amount regulating member, the design around the coating roller can be made compact, and the size of the liquid developer coating device can be reduced. Has an effect.

According to the fifth aspect of the present invention, the intermediate roller is provided with an elastic layer having an appropriate hardness so that the intermediate roller is uniformly brought into contact with the application roller in the axial direction and the maximum contact pressure is reduced. There is an excellent effect that it is possible to achieve both the holding at a certain value or more, and the intermediate roller can exhibit a sufficient function as a coating amount regulating member.

According to the sixth aspect of the present invention, the provision of the lubricating layer of the low friction member on the surface of the intermediate roller can reduce the frictional force generated at the contact portion with the developing roller as the member to be coated. Therefore, there is an excellent effect that the load on the drive system can be reduced, and at the same time, the mechanical stress applied to the intermediate roller and the developing roller can be reduced, and the life of parts can be extended.

According to the seventh to tenth aspects of the present invention,
By being able to adjust and change the speed of the intermediate roller with respect to the developing roller, the amount of application on the developing roller can be changed,
By using this coating apparatus in an image forming apparatus, there is an excellent effect that the image density can be adjusted and changed.

In particular, according to the invention of claim 8, in the liquid developer application device, the peripheral speed difference at the contact surface between the application roller and the intermediate roller that comes into contact with the application roller can be eliminated, thereby extending the life of the intermediate roller. There is an excellent effect that you can.

According to the ninth aspect of the present invention, in the liquid developer coating apparatus, the amount of application caused by slippage between the application roller and the intermediate roller that comes into contact with the application roller and the contact surface when no slippage occurs. Since the difference in the peripheral speed can be eliminated, there is an excellent effect that the fluctuation of the application amount is eliminated and the life of the intermediate roller can be extended at the same time.

According to the tenth aspect of the present invention, in the coating apparatus including the coating roller and the intermediate roller, the intermediate roller comes into contact with the developing roller as the member to be coated at an appropriate position, thereby providing a stable configuration. There is an excellent effect that coating can be performed.

According to the eleventh aspect of the present invention, the excessive amount of the liquid developer squeezed out at the contact portion with the application roller does not adhere to the surface end of the intermediate roller, and is transmitted further downstream to the cleaning. There is an excellent effect that it is possible to prevent the burden on the means from being increased, to prevent the inside of the machine from being scattered, and to prevent the liquid developer from being wasted.

According to the twelfth aspect of the present invention, the liquid developer adhering to the end surface of the intermediate roller can be prevented from adhering to the surface of the developing roller, so that such excess liquid developer adheres to the photosensitive member. This has an excellent effect that it can be prevented from affecting the image.

According to the thirteenth aspect of the present invention, it is possible to prevent the undeveloped liquid developer remaining on the developer carrier after the development from being used again for development as it is, and to prevent the occurrence of ghost. Has an effect.

According to the fourteenth aspect of the present invention, it is possible to prevent the liquid developer whose concentration has not been adjusted and which remains on the developer carrier after the development from being used again for development as it is, and to prevent the occurrence of density unevenness. Further, there is an excellent effect that the surface of the intermediate roller can be prevented from being damaged at the end of the cleaning means and the life of the roller can be extended.

According to the fifteenth aspect, by using the application roller having the non-engraved areas at both ends, the application area and the non-application area on the intermediate roller can be provided.
The non-applied area eliminates the excessive amount of application on both ends of the application surface on the developing roller, thereby affecting the image on the photoreceptor due to such excess liquid developer and increasing the load on the cleaning means. There is an excellent effect that such a problem can be reduced.

According to the sixteenth aspect of the present invention, by using an application roller having a non-engraving region at both ends, adjusting the length of the intermediate roller so that the end portion abuts the non-engraving region. In addition, there is an excellent effect that non-application regions can be provided on both ends of the application region on the intermediate roller.

According to the seventeenth aspect, by using the application roller having the non-engraved areas at both ends, the application area and the non-application area on the intermediate roller can be provided.
Further, by adjusting the length of the developing roller, which is a developer carrying member, so that the end of the developing roller is in contact with the non-coating area of the intermediate roller, the amount of coating that can be formed on both ends of the coating surface on the developing roller There is an excellent effect that excess portions can be eliminated.

According to the eighteenth aspect, the second aspect,
3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 1
The developing device having the liquid developer applying device of 3, 14, 15, 16 or 17 has an excellent effect that the life of the developing roller as a key part can be extended.

According to the nineteenth aspect, there is an excellent effect that image density fluctuations due to environmental fluctuations and the like can be prevented, and an image having a stable density can always be developed.

According to the twentieth aspect of the present invention, the image forming apparatus provided with the developing device according to the eighteenth or nineteenth aspect can extend the life of the developing roller which is a key part. In addition, it is possible to prevent image density fluctuations due to environmental fluctuations, to obtain an image with a stable density density at all times, and to adjust and change the image density according to the operator's preference. is there.

According to the twenty-first aspect, there is an excellent effect that a stable image can be obtained with a highly durable apparatus by an image forming apparatus provided with a photosensitive member having amorphous silicon as a surface layer.

According to the twenty-second aspect of the present invention, the coating device including the coating roller and the intermediate roller applies the coating to the developing roller as the member to be coated at an appropriate speed ratio, so that the coating can be performed uniformly and with little variation. There is an excellent effect that it can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a main part of a copying machine according to an embodiment.

FIG. 2 is a schematic sectional view showing a configuration of an intermediate roller of a coating device used in a developing device of the copying machine.

FIG. 3 is a schematic sectional view showing a configuration of a developing roller and a sweep roller of the developing device.

FIG. 4 is a schematic configuration diagram showing another configuration example of the copying machine.

FIG. 5 is a front view of an anilox roller serving as the application roller having a uniform pattern of concave portions formed on the surface.

FIGS. 6A, 6B, and 6C are enlarged perspective views showing examples of the shape of a concave portion formed on the surface of an application roller of the application device.

FIG. 7 is a graph showing a relationship between a developing electric field and a developing rate of the developing device.

FIG. 8 is a graph showing a relationship between a roller speed ratio between a developing roller of the developing device and an intermediate roller of the coating device, and an application amount of a liquid developer applied on the developing roller.

FIG. 9 is a schematic configuration diagram illustrating an example of a drive mechanism that drives the application roller and the intermediate roller by a single drive source while maintaining the peripheral speed of the application roller and the intermediate roller at a constant speed.

FIG. 10 is a schematic configuration diagram illustrating an example of a drive mechanism that drives the intermediate roller by a single drive source to rotate the application roller in a driven manner.

FIG. 11 is a schematic configuration diagram illustrating an example of a drive mechanism that eliminates slippage of the intermediate roller and drives the application roller and the intermediate roller by a single drive source.

FIG. 12 is a schematic configuration diagram showing an arrangement position of the intermediate roller with respect to the developing roller and the application roller.

FIG. 13 is a schematic configuration diagram illustrating an example of a coating apparatus configured to maintain a constant image density of a toner image using a density sensor.

FIG. 14 is a schematic configuration diagram showing a relationship among respective widths of the coating roller, the intermediate roller, the developing roller, and the photosensitive member.

FIGS. 15A and 15B are schematic configuration diagrams illustrating a relationship between a width of the application roller and a width of the intermediate roller.

FIG. 16 is a schematic configuration diagram for explaining a relationship among respective widths of the coating roller, the intermediate roller, the developing roller, and the photosensitive member.

FIGS. 17A and 17B are schematic configuration diagrams illustrating a relationship among respective widths of the coating roller, the intermediate roller, the developing roller, and the cleaning blade.

FIG. 18 is a schematic configuration diagram illustrating a relationship among respective widths of the intermediate roller, the developing roller, and the photoconductor.

FIG. 19 is a schematic configuration diagram showing a relationship between each width of the coating roller, the intermediate roller, the developing roller, and the photosensitive member and a width of a concave portion of the coating roller.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charger 3 Exposure device 4 Developing device 5 Transfer device 6 Photoconductor cleaning device 7 Static elimination lamp 401 Developer storage tank 402 Developing roller 402a Developing roller core metal 402b Developing roller elastic layer 402c Developing roller conductive layer 403 Sweep roller 403a Sweep roller core 403b Sweep roller elastic layer 403c Sweep roller conductive layer 404 Coating roller 404a Concavity formed on the surface of coating roller 404b Non-engraved area at end of coating roller 405 Intermediate roller 405a Intermediate roller 405a Core metal 405b Elastic layer of intermediate roller 405c Slip layer of intermediate roller 406 Stirring / conveying screw 407, 408, 411 Cleaning member 409 Doctor blade 410 Casing 412 Temporary storage unit 413 Transport screw 414 Foreign matter removing blade 415 Speed changing unit 416 Drive transmitting unit 417 Motor 418 Driver 419 Controller 420 Operating unit 421 Control board 422 Storage unit 423 One-way clutch 424 Density sensor 501 Transfer roller 502 Intermediate transfer body D Liquid developer

Claims (22)

[Claims] 1. A member to be coated on which a liquid developer carried on a surface of a coating member is applied by using a rotating coating member carrying a predetermined amount of liquid developer on the surface. A method of applying a liquid developer applied to the surface of the application member, wherein the contact surface with the surface of the application member moves in the same direction and at the same speed as the surface of the application member in contact with the surface of the application member; Liquid development carried on the surface of the coating member, on the surface of the intermediate coating member, the surface of which is in contact with the surface of the member to be coated and moves in the opposite direction to the surface of the member to be coated. And applying the liquid developer applied to the surface of the intermediate application member to the surface of the member to be applied. 2. A coating member which rotates while carrying a predetermined amount of liquid developer on a surface thereof, wherein a contact surface of the coating member which is in contact with the surface of the coating member is in the same direction as the surface of the coating member. And moving at a constant speed, and in contact with the surface of the member to be coated on which the liquid developer is applied, and the contact surface with the surface of the member to be coated moves in the opposite direction to the surface of the member to be coated. An application device for a liquid developer, comprising: an application member. 3. A coating apparatus for a liquid developer according to claim 2, wherein said coating roller as said coating member having a concave portion of a uniform pattern formed on a surface thereof, said coating roller being in contact with a surface of said coating roller. An application amount regulating member for regulating an application amount of the liquid developer carried on the surface. 4. The liquid developer coating device according to claim 3, wherein the intermediate coating member also serves as the coating amount regulating member. 5. The liquid developer coating device according to claim 4, wherein the intermediate coating member has a hardness of at least 30 degrees according to JIS-A.
An application device for a liquid developer, which is an intermediate roller having an elastic layer of 0 ° or less. 6. The liquid developer coating device according to claim 4, wherein the intermediate coating member has a smooth layer made of a low friction member on a surface thereof. apparatus. 7. The liquid developer coating device according to claim 2, wherein the rotation speed of the coating member and the intermediate coating member is maintained at a constant speed. And a speed changing means for changing a rotation speed of the liquid developer and the intermediate coating member. 8. The liquid developer application device according to claim 2, wherein the application member and the intermediate application member are driven by a single drive source. Liquid developer coating device. 9. The liquid developer coating device according to claim 2, wherein the relationship between the surface speed Va of the coating member and the surface speed Vm of the intermediate coating member is determined. , Va <Vm, a driving unit for forcibly driving the coating member and the intermediate coating member, and a drive transmission unit for transmitting the drive of the driving unit to the coating member. A one-way rotation mechanism that allows free rotation of the liquid developer in the forward direction. 10. The liquid developer applying device according to claim 2, 3, 4, 5, 6, 7, 8 or 9, wherein a position of a tangent line between said intermediate roller as said intermediate applying member and said member to be applied is provided. However, a plane including the rotation center line of the application roller as the coating member and the rotation center line of the intermediate roller, and the intersection line with the surface of the intermediate roller as a boundary, the upstream of the intermediate roller in the rotation direction of the intermediate roller An application device for a liquid developer, which is provided at a position including an intersection line. 11. The method of claim 2, 3, 4, 5, 6, 7, 8, 9.
Alternatively, in the liquid developer applying device, the width of the intermediate applying member is smaller than the width of the applying member. 12. The method of claim 2, 3, 4, 5, 6, 7, 8,
9. The liquid developer application device according to 9, 10, or 11, wherein the width of the intermediate application member is larger than the width of the member to be applied. 13. The method of claim 2, 3, 4, 5, 6, 7, 8,
The liquid developer application device of 9, 10, 11 or 12, further comprising a cleaning member that abuts on the surface of the intermediate application member and removes a substance attached to the surface of the intermediate application member. An apparatus for applying a liquid developer, comprising: 14. A liquid developer applying apparatus according to claim 13, wherein a width of a portion of said cleaning member which abuts on a surface of said intermediate applying member is larger than a width of said applying member. Agent application device. 15. The method of claim 2, 3, 4, 5, 6, 7, 8,
The liquid developer application apparatus according to any one of 9, 10, 11, 12, 13 and 14, wherein a uniform engraving is applied to a surface of the application member except for both end portions of the application member. Developer application device. 16. The liquid developer coating device according to claim 15, wherein the width of the engraving applied to the surface of the coating member is smaller than the width of the intermediate coating member. Coating device. 17. The liquid developer applying apparatus according to claim 15, wherein the width of the engraving applied to the surface of the applying member is smaller than the width of the member to be applied. Agent application device. 18. An electrostatic latent image formed on a surface of an image bearing member,
A developing device for visualizing an image from a liquid developer applied to a surface of a developer carrier moving in contact with a surface of the image carrier, wherein a liquid for applying the liquid developer to a surface of the developer carrier is provided. Claims 2, 3, 4, 5, as a developer coating device.
6, 7, 8, 9, 10, 11, 12, 13, 14, 1
A developing device using the liquid developer application device of 5, 16, or 17. 19. The developing device according to claim 18, wherein a relationship between a peripheral speed Vm of said intermediate coating member and a moving speed Vd of a surface of said developer carrier is Vd <Vm <2 × Vd. Characteristic developing device. 20. An image bearing member, image forming means for forming an electrostatic latent image on the surface of the image bearing member, and an electrostatic latent image formed on the surface of the image bearing member by the image forming means. An image forming apparatus comprising: a developing device that visualizes an image with a developer; wherein the developing device according to claim 18 is used as the developing device. 21. The image forming apparatus according to claim 20, wherein a photoconductor having a surface layer made of amorphous silicon is used as said image carrier. 22. The image forming apparatus according to claim 20, wherein a pattern image forming means for forming a pattern image in a non-image area on the image carrier, and a density detecting means for detecting an image density of the pattern image. Changing the moving speed of the coating member and the intermediate coating member in accordance with the image density of the pattern image detected by the density detecting means to thereby adjust the amount of the liquid developer applied to the surface of the developer carrier. An image forming apparatus, comprising: a developer application amount control unit that controls the amount of developer applied.