JP2001249547A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrostatic latent image carrier with which a high- definition image is formed. SOLUTION: The developing device 5 has an electrostatic latent image carrier 2 formed with an electrostatic latent image thereon and having a contact angle with water in 20 deg.C and 50% RH of a 50-100 degree and surface average roughness of 0.01-2.0 μm, a liquid coloration medium carrier 7 which is disposed closely to the electrostatic latent image carrier 2 and deposites a liquid coloration medium L1 on the electrostatic latent image carrier 2 to develop the electrostatic latent image, a voltage applying means 26 for applying bias voltage between the liquid coloration medium carrier 7 and the electrostatic latent image carrier 2, and a transfer roller 8 for transferring a toner image formed on the electrostatic latent image carrier 2 in a paper sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used for an image forming apparatus such as an electrophotographic apparatus, and more particularly to a wet developing device for developing an electrostatic latent image with a liquid coloring medium.

[0002]

2. Description of the Related Art Developing devices employed in image forming apparatuses such as copying machines utilizing electrophotography are roughly classified into dry developing devices and wet developing devices. Among them, a liquid coloring medium used in a wet developing device is a dispersion of charged granular toner in a carrier liquid. For example, such a liquid coloring medium is formed on the surface of an electrostatic latent image carrier such as a photosensitive drum. When a liquid coloring medium is supplied, the toner is electrophoresed, adheres to the electrostatic latent image, and is visualized.

For example, a liquid coloring medium in which a toner composed of carbon black coated with a resin is dispersed in a carrier liquid composed of an aliphatic hydrocarbon such as “IsoparG” (trade name, manufactured by Exxon Corporation) is used as an electrostatic latent image. The liquid coloring medium is supplied between the surface of the electrostatic latent image carrier on which is formed and the counter electrode arranged at a uniform interval on the surface to bring the liquid coloring medium into contact with the surface of the electrostatic latent image carrier, and the carrier liquid The electrostatic latent image is developed by utilizing the electrophoresis phenomenon of charged toner in the inside.

In a wet developing apparatus using a liquid coloring medium,
There is an advantage that high resolution can be obtained due to the fineness of the toner particles and the like as compared with the dry developing device.

This liquid coloring medium is called a two-component liquid coloring medium because a carrier liquid is used for charging and moving the toner.

In a wet developing apparatus using such a two-component liquid coloring medium, the liquid coloring medium contacts not only the electrostatic latent image but also the non-latent image portion, and thus adheres to the electrostatic latent image carrier. The amount of the liquid coloring medium taken out is increased. For this reason, it is necessary to provide a means for removing excess liquid coloring medium on the surface of the electrostatic latent image carrier.

Further, since the liquid coloring medium comes into contact with the non-latent image portion, toner adheres to the non-latent image portion due to the action of residual charges in the non-latent image portion, and the image is soiled. is there.

Further, when the toner on the electrostatic latent image carrier is transferred to a transfer material to obtain a final image, the liquid adhering to the electrostatic latent image carrier regardless of the latent image portion and the non-latent image portion is obtained. Since the coloring medium is transferred to the transfer material, the transfer material immediately after the transfer of the toner image is in a wet state with the liquid coloring medium.

Therefore, it is necessary to evaporate the solvent at the time of fixing, for example, before the transfer material is discharged out of the apparatus.

The amount of heat for evaporating the solvent not only occupies most of the amount of heat used in the image forming apparatus, but also around the image forming apparatus, the vapor concentration of the organic liquid evaporated by drying increases, and the amount of heat used increases. May cause discomfort to the person.

As a wet developing apparatus for solving the above problems, there is one disclosed in Japanese Patent Application Laid-Open No. 55-143565. This uses a liquid coloring medium in which a coloring material is dispersed or dissolved in a liquid, and a non-contact protruding development at a gap between the liquid coloring medium on the liquid coloring medium carrier and the electrostatic latent image carrier, that is, a developing gap. Alternatively, jumping development is performed. Hereinafter, such a developing method is referred to as a non-contact wet developing method.

The liquid coloring medium used in the non-contact wet developing system is such that the entire liquid behaves as a toner without the color material moving in the liquid, and corresponds to the carrier liquid in the two-component liquid coloring medium. For this reason, it is called a one-component liquid coloring medium.

Here, an image forming apparatus using a non-contact wet developing system will be described below.

In a non-contact wet developing type image forming apparatus,
An electrostatic latent image carrier on which an electrostatic latent image is formed is rotatably supported by the apparatus main body. On the outer periphery of the electrostatic latent image carrier, a charger for uniformly charging the electrostatic latent image carrier, an exposure optical system for forming an electrostatic latent image on the electrostatic latent image carrier, and an electrostatic latent image are provided. A wet developing device for developing a visible image, a cleaning device for removing a coloring medium remaining on the outer surface of the electrostatic latent image carrier,
Static eliminators for removing the electrostatic latent image charge remaining on the electrostatic latent image carrier are sequentially arranged along the rotation direction of the electrostatic latent image carrier.

Inside the developing device, there is a liquid tank containing a liquid coloring medium, and the liquid coloring medium carrying the liquid coloring medium is supplied to the outer surface of the electrostatic latent image carrier to visualize the electrostatic latent image. body,
A sponge-like foaming roller for supplying a liquid coloring medium, which absorbs the liquid coloring medium in the liquid tank and supplies it to the liquid coloring medium carrier, is provided. The liquid tank is connected with a carrier liquid cartridge for supplying a carrier liquid for dispersing the toner and a concentrated liquid coloring medium cartridge for supplying a concentrated liquid coloring medium.

The cleaning device includes a cleaning foam roller that is in pressure contact with the electrostatic latent image carrier, and a resilient cleaning blade for the electrostatic latent image carrier that is also in pressure contact with the electrostatic latent image carrier. A cleaning liquid cartridge and a waste liquid treatment tank are connected to the cleaning device.

On the side of the image forming apparatus, a paper cassette containing paper is provided. A transfer roller for transferring the toner image on the electrostatic latent image carrier to a sheet is disposed at a position facing the developing surface of the electrostatic latent image carrier. A transfer material separating device that separates the paper from the electrostatic latent image carrier and a fixing device that fixes the toner image on the paper are sequentially arranged behind the transfer roller in the transport direction.

Next, the operation of the image forming apparatus thus configured will be described.

When image formation is started, the surface of the electrostatic latent image carrier is uniformly charged, and an electrostatic latent image is formed on such an electrostatic latent image carrier by an exposure optical system. And
The liquid coloring medium is supplied to the surface of the liquid coloring medium carrier by rotating the liquid coloring medium supply foam roller partially immersed in the liquid tank.

The liquid coloring medium supplied to the liquid coloring medium carrier is adjusted to a predetermined thickness by rotating the liquid coloring medium regulating member. Since a developing gap is formed between the liquid coloring medium film formed on the surface of the liquid coloring medium carrier and the surface of the electrostatic latent image carrier, the electric charge forming the electrostatic latent image is transferred to the developing unit. Upon arrival, the electric field of the electric charge causes the liquid coloring medium film to bulge or jump toward the electric charge and adhere to the electrostatic latent image carrier, whereby the electrostatic latent image is developed.

As a result, the electrostatic latent image formed on the electrostatic latent image carrier is visualized and transferred to a sheet by a transfer roller. Thereafter, the sheet is separated from the electrostatic latent image carrier by the transfer material separating device and transported to the fixing device, where the toner image is fixed.

The residual coloring medium remaining on the electrostatic latent image carrier is removed by a cleaning device, and the residual electrostatic latent image on the electrostatic latent image carrier is removed by a static eliminator.

[0023]

Here, in order to form a high quality image with a non-contact type wet developing device, a liquid colored medium is formed on a latent electrostatic image bearing member by a toner image in accordance with an electrostatic latent image. It is necessary to transfer the toner image on the electrostatic latent image carrier to a sheet with high efficiency.

Accordingly, it is an object of the present invention to provide a developing device having an electrostatic latent image carrier capable of forming a high quality image.

[0025]

In order to solve this problem, a developing device of the present invention has a contact angle with water at 20 ° C. and 50% RH of not less than 50 degrees and not more than 100 degrees;
An electrostatic latent image carrier having an average surface roughness of not less than 0.01 μm and not more than 2.0 μm to form an electrostatic latent image; A liquid coloring medium carrier for adhering a liquid coloring medium on the image carrier to visualize the electrostatic latent image, and a voltage for applying a bias voltage between the liquid coloring medium carrier and the electrostatic latent image carrier The configuration includes an application unit and a transfer roller that transfers a toner image formed on an electrostatic latent image carrier to a sheet.

Thus, the liquid colored medium is visualized as a toner image on the electrostatic latent image carrier in accordance with the electrostatic latent image, and is transferred to paper with high efficiency, thereby forming a high quality image. Becomes possible.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention has a contact angle with water at 20 ° C. and 50% RH of 100%.
The electrostatic latent image carrier, on which an electrostatic latent image is formed, is disposed in close proximity to the electrostatic latent image carrier, and a liquid coloring medium is adhered onto the electrostatic latent image carrier to form a static image. A liquid coloring medium carrier for visualizing the electrostatic latent image; a voltage applying means for applying a bias voltage between the liquid coloring medium carrier and the electrostatic latent image carrier; And a transfer roller for transferring the formed toner image onto a sheet. The liquid coloring medium is visualized as a toner image according to the electrostatic latent image on the electrostatic latent image carrier, and is transferred to the sheet with high efficiency. This has the effect that a high quality image can be formed.

According to a second aspect of the present invention, in the first aspect of the present invention, the electrostatic latent image carrier is maintained at 20 ° C., 5 ° C.
A developing device having a contact angle with water at 0% RH of 50 degrees or more, and has an effect that a toner image on an electrostatic latent image carrier can be transferred onto a sheet with high efficiency.

According to a third aspect of the present invention, there is provided a developing device according to the first or second aspect, wherein the surface average roughness of the electrostatic latent image carrier is 0.01 μm or more and 2.0 μm or less. This is an apparatus and has an effect that a toner image on an electrostatic latent image carrier can be transferred to a sheet with high efficiency.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. In these drawings, the same members are denoted by the same reference numerals, and duplicate description is omitted.

FIG. 1 is a sectional view showing an image forming apparatus using a developing device according to an embodiment of the present invention, and FIG.
FIG. 4 is a cross-sectional view illustrating a developing device in the image forming apparatus of FIG.

In FIG. 1, an electrostatic latent image carrier 2 on which an electrostatic latent image is formed is rotatably supported by an image forming apparatus 1. An organic photoconductor (OP) is provided on the surface of the electrostatic latent image carrier 2.
C), an amorphous silicon (a-Si) -based or selenium (Se) -based photosensitive receiving layer is applied. In the present embodiment, the electrostatic latent image carrier 2 has a drum shape, but may have a belt shape.

Here, the temperature of the electrostatic latent image carrier 2 is set to 20.degree.
The contact angle with water at% RH is 50 degrees or more and 100%.
Degrees or less.

This is because if the contact angle between the electrostatic latent image carrier 2 and water exceeds 100 degrees, the wettability of the liquid coloring medium L1 on the electrostatic latent image carrier 2 decreases, so that the electrostatic latent image This is because the electrophoresis of the liquid coloring medium L1 in accordance with the above is hindered, making it difficult to visualize the toner image as a toner image, and lowering the developing resolution.

On the other hand, if the contact angle between the electrostatic latent image carrier 2 and water is less than 50 degrees, the liquid coloring medium L on the electrostatic latent image carrier 2
This is because, since the wettability of the toner image 1 becomes high, it is difficult to transfer the toner image on the electrostatic latent image carrier 2 onto the sheet with high efficiency, and the printing resolution is reduced.

The average surface roughness of the electrostatic latent image carrier 2 is not less than 0.01 μm and not more than 2.0 μm.

This is because, when the surface average roughness of the electrostatic latent image carrier 2 exceeds 2.0 μm, the adhesion between the electrostatic latent image carrier 2 and the paper 16a as the transfer material is reduced, This is because it is difficult to transfer the toner image on the electro-latent image carrier 2 onto paper with high efficiency, and the printing resolution is reduced.

On the other hand, if the surface average roughness of the electrostatic latent image carrier 2 is less than 0.01 μm, it is difficult to maintain the processing accuracy of the electrostatic latent image carrier 2, so that the surface average roughness becomes non-uniform and toner This is because transferability becomes unstable.

A charger 3 for uniformly charging the electrostatic latent image carrier 2 using corona discharge is provided on the outer periphery of the electrostatic latent image carrier 2, and a laser is turned on / off by information from a host computer. An exposure optical system 4 for forming an electrostatic latent image on the electrostatic latent image carrier 2; the toner in the liquid coloring medium L1 contributing to development is transferred to the electrostatic latent image to make the electrostatic latent image visible A cleaning device 13 including a wet developing device 5 for developing an image, a light emitting diode, etc., for removing toner remaining on the outer peripheral surface of the electrostatic latent image carrier 2, and an electrostatic latent image carrier after removing residual toner Static eliminators 11 for removing the electrostatic latent image charges remaining on the electrostatic latent image carrier 2 by light irradiation are sequentially arranged along the rotation direction of the electrostatic latent image carrier 2.

As shown in FIG. 2, a liquid tank 12 is formed inside a housing 5a of the developing device 5, and a liquid coloring medium L1 is stored therein.

Further, the liquid coloring medium L1 is supplied to the outer peripheral surface of the electrostatic latent image carrier 2 to make the electrostatic latent image formed on the electrostatic latent image carrier 2 visible as a toner image. The body 7 is provided so as to protrude a part of the outer peripheral surface.

Further, a sponge-like foaming roller 6 for supplying a liquid coloring medium which absorbs the liquid coloring medium L1 in the liquid tank 12 and supplies it to the liquid coloring medium carrier 7 is pressed against the liquid coloring medium carrier 7 by pressing. Are located.

Then, a liquid coloring medium regulating member 21 for regulating the film thickness of the liquid coloring medium L1 supplied to the surface of the liquid coloring medium carrier 7 forms a uniform gap in the liquid coloring medium carrier 7 above the housing 5a. It is placed close to holding.

A liquid coloring medium regulating member cleaning blade 22 is provided in pressure contact with the surface of the liquid coloring medium regulating member 21. Thereby, the liquid coloring medium regulating member 2
The liquid coloring medium L1 attached to the housing 1 is removed and dropped and collected into the liquid tank 12, and the housing 5 cooperates with the liquid coloring medium carrier 7 and the liquid coloring medium regulating member 21.
The liquid coloring medium L1 housed in a is shut off from the outside air. Therefore, the phenomenon that the carrier liquid in which the toner is dispersed evaporates and the concentration of the liquid coloring medium increases can be prevented.

The developing device 5 is provided with voltage applying means 26 for applying a bias voltage between the liquid coloring medium carrier 7 and the electrostatic latent image carrier 2.

The liquid coloring medium L1 is made of, for example, Iso.
For example, 1E + 12 composed of an aliphatic hydrocarbon such as parG
It is composed of a carrier liquid having a high specific resistance of Ω · cm or more and a toner composed of, for example, carbon black coated with a resin and positively charged and dispersed in the carrier liquid.

As shown in FIG. 1, the liquid tank 12 is connected to a carrier liquid cartridge 14 for supplying a carrier liquid for dispersing toner and a concentrated liquid coloring medium cartridge 15 for supplying a concentrated liquid coloring medium.

The cleaning device 13 is composed of a sponge-like cleaning foam roller 9 that is in pressure contact with the electrostatic latent image carrier 2 and an elastic body such as rubber. A latent image carrier cleaning blade 10 is provided. The cleaning device 13 is connected with a cleaning liquid cartridge 19 for replenishing a cleaning liquid using a carrier liquid for cleaning the electrostatic latent image carrier 2 and a waste liquid processing tank 20 for collecting waste liquid.

On the side of the image forming apparatus 1, there is provided a paper cassette 16 containing paper 16a as a material to be transferred. A transfer roller 8 for transferring the toner image formed on the electrostatic latent image carrier 2 to the sheet 16a is provided at a position facing the developing surface of the electrostatic latent image carrier 2 with the sheet 16a interposed therebetween. Are located.

Further, behind the transfer roller 8 in the conveying direction, a transfer material separating device 17 for removing electricity from the paper 16a by corona discharge and separating it from the electrostatic latent image carrier 2, and a transfer material separating device 17 A fixing device 18 for fixing the toner image transferred to the paper 16a separated from the electrostatic latent image carrier 2 by the above-mentioned is sequentially arranged. And paper 1
The toner image is fixed to 6 a by the pressure and heat when passing through the inside of the fixing device 18.

The operation of the thus configured image forming apparatus will be described below.

When image formation is started, first, as a charging step, corona discharge is performed by a charger 3 connected to a high-voltage power supply, and the surface of the electrostatic latent image carrier 2 is uniformly charged. Next, in the exposure step, the laser of the exposure optical system 4 is turned on / off by information sent from the host computer, and the charge on the surface of the electrostatic latent image carrier 2 rotated in the circumferential direction is partially eliminated. As a result, an electrostatic latent image is formed.

In the subsequent development step, the liquid tank 12
The liquid coloring medium L1 is supplied to the surface of the liquid coloring medium carrier 7 by rotating the liquid coloring medium supplying foam roller 6 partially immersed in the liquid coloring medium L1. The liquid coloring medium L1 supplied to the liquid coloring medium carrier 7 is adjusted to a predetermined thickness by rotating the liquid coloring medium regulating member 21.

The paper 16a is conveyed from the paper cassette 16 to the transfer roller 8. Then, the development of the toner image on the electrostatic latent image carrier 2 is completed, and the paper 16 a is transferred to the transfer roller 8.
The transfer roller 8 comes into contact with the electrostatic latent image carrier 2 at substantially the same time when the transfer roller 8 is conveyed. Then, by applying a predetermined level of transfer bias, the toner image on the electrostatic latent image carrier 2 is transferred to the sheet 16a.

Here, since the paper 16 a is a dielectric, it is charged by high voltage and is electrostatically attracted to the electrostatic latent image carrier 2. Therefore, almost at the same time as the paper 16a is conveyed to the transfer roller 8, corona discharge is performed by the transfer material separation device 17 by an AC bias, and the paper 16a is discharged. When the sheet 16a is completely discharged, the electrostatic attraction force between the sheet 16a and the electrostatic latent image carrier 2 decreases, and the sheet 16a is separated from the electrostatic latent image carrier 2 by stiffness and its own weight. .

The separated paper 16a is conveyed to the fixing device 18, where the toner image is fixed, and the image formation is completed.

On the other hand, the toner remaining on the electrostatic latent image carrier 2 without being transferred to the paper 16 a is
Removed by That is, the cleaning liquid supplied from the cleaning liquid cartridge 19 is diffused to the cleaning foam roller 9, and the cleaning foam roller 9 and the cleaning blade 1 for the electrostatic latent image carrier are dispersed.
0 cleaning. Further, the electrostatic latent image carrier 2
Is removed by the charge remover 11. As a result, the electrostatic latent image carrier 2 enters a standby state for forming a new image.

As described above, according to the developing device of the present embodiment, the liquid colored medium is visualized as a toner image on the electrostatic latent image carrier in accordance with the electrostatic latent image, and is transferred to the sheet with high efficiency. As a result, a high-quality image can be formed.

[0059]

As described above, according to the present invention, the liquid colored medium is visualized as a toner image on the electrostatic latent image carrier in accordance with the electrostatic latent image and is transferred onto the paper with high efficiency. Therefore, an effective effect that a high quality image can be formed can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an image forming apparatus using a developing device according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a developing device in the image forming apparatus of FIG. 1;

[Explanation of symbols]

 2 electrostatic latent image carrier 5 developing device 7 liquid colored medium carrier 8 transfer roller 26 voltage applying means L1 liquid colored medium

Claims (3)

[Claims] 1. An electrostatic latent image carrier having a contact angle with water at 20 ° C. and 50% RH of 100 ° or less, on which an electrostatic latent image is formed, and A liquid coloring medium carrier, which is disposed in close proximity and adheres a liquid coloring medium on the electrostatic latent image carrier to visualize the electrostatic latent image; a liquid coloring medium carrier and the electrostatic latent image carrier A developing device comprising: voltage applying means for applying a bias voltage to a body; and a transfer roller for transferring a toner image formed on the electrostatic latent image carrier to a sheet. 2. The image forming apparatus according to claim 1, wherein said electrostatic latent image carrier is at 20.degree.
2. The developing device according to claim 1, wherein a contact angle of H with water is 50 degrees or more. 3. The electrostatic latent image bearing member has an average surface roughness of 0.5.
3. The developing device according to claim 1, wherein the thickness is not less than 01 [mu] m and not more than 2.0 [mu] m.