JP2001337530A - Liquid development electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce fogging on an image by lowering the viscosity of pre-wet liquid while using the same pre-wet liquid as the carrier liquid of liquid toner by taking the recycling of the liquid toner into consideration. SOLUTION: This liquid development electrophotographic device is provided with a developing device which uses the liquid toner as liquid developer and by which a toner image is formed by sticking the toner particles of the liquid toner to an image supporting body in accordance with an electric field generated with the image supporting body and a pre-wetting device to apply a pre-wet layer to the surface of the image supporting body at a position before the developing device. The pre-wetting device is constituted of a means to heat and supply the pre-wet liquid and a pre-wet liquid applying roller to apply the film of heated pre-wet liquid to the surface of the image supporting body while it abuts on the image supporting body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid developing electrophotographic apparatus using a high-viscosity, high-concentration liquid toner. The present invention relates to a liquid-developed electrophotographic apparatus which can be applied to a liquid.

[0002]

2. Description of the Related Art In an electrophotographic apparatus in which an electrostatic latent image is formed on a photosensitive member (photosensitive drum), toner is adhered to the image, and the image is transferred to paper and fixed, a dry type using powder toner is widely used. Used.

However, the powder toner has a problem that the toner is scattered, and the toner particles have a particle size of 7 to 10 μm.
There is a problem that the resolution is poor due to the large value of m.

Therefore, when high resolution is required, a wet type using a liquid toner is used. Liquid toner has toner particles as small as about 1 μm,
Due to the large charge amount, disturbance of the toner image hardly occurs,
This is because high resolution can be realized.

In a conventional wet-type electrophotographic apparatus, a low-viscosity liquid toner in which a toner is mixed with an organic solvent at a ratio of 1 to 2% is used as a developing solution. However, such a developer uses an organic solvent that is harmful to the human body and uses a large amount of the organic solvent because of its low toner concentration, which has a serious problem of causing environmental problems.

Against this background, the invention of a liquid developing type electrophotographic apparatus using a high-viscosity, high-concentration developer constituted by dispersing a high-concentration toner in silicone oil or the like has been proposed. (For example, see JP-A-11-65)
287). The use of this liquid toner has the advantage that the problem of harm to the human body does not occur and the high toner concentration eliminates the need to use a large amount of developer.

When a non-volatile, high-viscosity, high-concentration liquid toner is used, the high-viscosity toner is used to prevent the high-viscosity toner from adhering to the non-exposed portion of the electrostatic latent image formed on the photosensitive member. Before applying the toner, a pre-wetting process of applying a pre-wetting liquid such as silicone oil to the photoconductor is performed.

According to the pre-wet layer applied by this pre-wet treatment, it is possible to reduce the adhesion of toner to the unexposed portion of the photoreceptor, that is, to reduce the fog on the image. The lower the viscosity, the greater the effect.

However, considering the recycling of liquid toner, it is desirable to use the same carrier liquid and pre-wet liquid for the liquid toner. It is not possible to select a liquid having an optimum viscosity only from the viewpoint of a pre-wet liquid without considering the characteristics as a carrier liquid.

In addition, when the pre-wet liquid is applied after exposing the photoreceptor, the electrostatic latent image formed on the photoreceptor is disturbed to deteriorate the image. There was a point. In addition, electrophotographic devices
In addition to the mechanism for exposing the photoreceptor, a mechanism for discharging the photoreceptor and a mechanism for charging the photoreceptor are required, and there has been a problem that the configuration is complicated and large.

[0011]

SUMMARY OF THE INVENTION Therefore, the present invention reduces the viscosity of the pre-wet liquid while using the same pre-wet liquid as the carrier liquid of the liquid toner in consideration of recycling of the liquid toner. The aim is to reduce fog on the image.

Further, according to the present invention, after exposing the photoreceptor,
It is an object of the present invention to obtain a good image quality without disturbing a latent image by adopting a configuration of applying a pre-wet liquid, and to simplify a configuration of a photoconductor charge eliminating mechanism and a photoconductor charging mechanism.

[0013]

A liquid developing electrophotographic apparatus according to the present invention uses a liquid toner as a liquid developing solution and supplies the liquid toner in contact with an image support on which an electrostatic latent image is formed. A developing device for forming a toner image by adhering toner particles of liquid toner to the image support in accordance with an electric field generated between the image support and the image supporting device; A pre-wet device for applying a pre-wet layer to the surface of the body. This pre-wet apparatus comprises a means for heating and supplying a pre-wet liquid, a pre-wet liquid applying roller for abutting the image support and applying a film of the heated pre-wet liquid to the surface of the image support. Consists of

Further, the pre-wetting apparatus of the liquid developing electrophotographic apparatus of the present invention is arranged such that the film of the supplied pre-wet liquid is brought into contact with the image support at a position before the exposure in the direction of the process to expose the image support. And a pre-wet liquid applying roller for applying the liquid to the surface of the pre-wet. A high-voltage DC voltage and an AC bias voltage are applied to the pre-wet liquid application roller together to charge the image support, and the charged image support is exposed based on image data.

Further, the pre-wetting apparatus of the liquid developing electrophotographic apparatus of the present invention is arranged such that a film of the supplied pre-wet liquid is brought into contact with the image support at a position before the exposure in the process traveling direction to contact the image support. And a pre-wet liquid applying roller for applying the liquid to the surface of the pre-wet. An AC bias voltage is applied to the pre-wet liquid application roller to remove charges from the image support. Then, the image support is charged, and the charged image support is exposed based on the image data.

Further, the pre-wetting device of the liquid developing electrophotographic apparatus according to the present invention comprises: a blade support having a plurality of through slits or through holes;
And a blade mounted to extend further from the tip. The pre-wet liquid is thinly and uniformly applied onto the image support by flowing the pre-wet liquid from the upper surface of the blade to the image support surface from a plurality of through slits or through holes provided in the blade support.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail according to embodiments. FIG. 1 is a diagram illustrating a liquid developing type electrophotographic apparatus embodying the present invention.

First, the overall outline of the liquid developing electrophotographic apparatus will be described with reference to FIG. A developing unit is provided at the bottom of the apparatus, an intermediate transfer unit is provided thereon, and a transfer fixing unit is provided at the top of the apparatus. Since the illustrated apparatus is provided with the transfer fixing unit that generates a large amount of heat at the top of the apparatus, heat can be efficiently discharged from the apparatus. Further, since the developing section for handling the liquid toner is provided at the lowermost portion of the apparatus, even if the liquid toner leaks, the printing medium is hardly stained.

The developing section includes yellow / magenta / cyan /
It is provided in association with black. Photosensitive drums (photosensitive members) 11 to 14 are provided, respectively, and a charger for charging the photosensitive drums 11 to 14 to about 700 V is provided (not shown). Exposure indicated by an arrow is performed by charging the charged photosensitive drums 11 to 14 based on image data, for example, 7 times.
This is performed using laser light having a wavelength of 80 nm. As a result, an electrostatic latent image is formed on the photosensitive drums 11 to 14 in which the potential of the exposed portion is about 100 V. Further, a static eliminator (not shown) is provided to eliminate residual potential on the photosensitive drums 11 to 14.

The developing roller is biased to a predetermined voltage such as about 400 V to 600 V, and the photosensitive drums 11 to 1 are biased.
4, the positively charged toner is supplied to the photosensitive drums 11 to 14. As a result, toner is adhered to the exposed portions on the photosensitive drums 11 to 14 charged to about 100 V, and the electrostatic latent images on the photosensitive drums 11 to 14 are developed to form images. The toner supply roller includes one or a plurality of rollers for each color toner, and has a toner viscosity of 400 to 4000 mPa · S and a carrier viscosity of 20 to 500 cSt, preferably 100 cSt.
Is conveyed while being spread thinly from the toner pool to apply the liquid toner on the developing roller with a predetermined layer thickness (for example, 4 to 10 μm).

Intermediate transfer roller 1 as first intermediate transfer member
5 are biased to about -800 V, and each photosensitive drum 1
Photosensitive drums 11 to 14 according to an electric field between the photosensitive drums 11 to 14
The toner attached to is transferred. This intermediate transfer roller 1
5 firstly transfers, for example, yellow toner attached to the first photosensitive drum 11, subsequently transfers, for example, magenta toner attached to the second photosensitive drum 12, For example, cyan toner attached to the three photosensitive drums 13 is transferred, and finally, the fourth photosensitive drum 1 is transferred.
For example, the black toner attached to the toner image 4 is transferred. Thus, the first to fourth photosensitive drums 11 to 1
The four-color toner image developed on the intermediate transfer roller 1 is sequentially rotated by rotating the intermediate transfer roller 15 four times.
5 to form a color image. The cleaning blade comes in contact with the intermediate transfer roller at an appropriate timing to remove the toner and the pre-wet liquid remaining thereon.

Thereafter, the four-color image is electrostatically transferred onto the intermediate transfer belt 16 having a belt structure as a second intermediate transfer member, and is transferred after the carrier liquid is removed in the carrier removing section. The toner image is heated and melted at a contact portion with the print medium, and is melt-transferred to the print medium.
The image formed by the liquid toner on the intermediate transfer belt 16 contains a carrier liquid.
This carrier oil is removed.

As in the present invention, 400 to 4000 mPa
When a liquid toner developer having a high viscosity such as S is used, the toner adheres to the non-exposed portion of the photosensitive drum in order to improve image quality such as preventing toner fogging during development. A configuration is adopted in which a pre-wet layer is applied to the surface of the photosensitive drum at a position in front of the developing device in order to prevent the pre-wet layer from being released, and the developing roller does not break the pre-wet layer. A configuration is adopted in which the photosensitive drum is brought into contact with the contact pressure of about the same level.

As described above, the pre-wet liquid is an insulating oil which is applied uniformly and in a thin layer on the photosensitive drum, but the same liquid as the carrier agent used for the liquid toner is used. Is desirably applied to the surface of the photosensitive drum in a thickness of 4 to 5 μm.

FIG. 2 is a diagram showing a first example of a configuration in which a pre-wet liquid is applied on a photoreceptor. The pre-wet liquid is supplied from a reservoir 33 with a heater to the pre-wet liquid application roller 30 via supply rollers 32 and 31, and from there, is uniformly coated on the photoreceptor 10 in a thin layer. Is done.

At this time, the pre-wet liquid is heated at any position before being applied to the photoreceptor 10. This is, as shown, a pre-wet liquid reservoir 33.
And a heater for heating.
By keeping the temperature warm.

Alternatively, a heater may be provided inside the pre-wet liquid application roller 30 so that the pre-wet liquid is applied to the photoreceptor 10 while being heated on the surface of the pre-wet liquid application roller 30. it can.

The following table shows the relationship between the temperature and the kinematic viscosity of dimethyl silicone oil. According to this table, when the temperature was changed from 0 ° C. to 100 ° C. for each of the three types of nominal viscosities of 20, 50 and 100 cs, the apparent viscosity greatly decreased as the temperature increased. I have.

As described above, by heating the pre-wet liquid, while using the same toner carrier liquid, only the viscosity of the pre-wet liquid is reduced to improve the image quality by reducing the fog of the developed image. be able to.

[0030] In the drawing, as described above, the developing roller 40 forms a thin layer of liquid toner conveyed while extending thinly from a toner reservoir (not shown) via the applicator rollers 42 and 41, and then, The toner layer on the developing roller is supplied onto the photoreceptor 10 while maintaining the two-layer structure of the pre-wet liquid film on the photoreceptor 10. Then, according to the electric field between the developing roller 40 and the photoconductor 10, the toner particles that are positively charged are supplied to the photoconductor 10, thereby performing the development.

FIG. 3 is a view showing a second example of a configuration in which a pre-wet liquid is applied onto a photoreceptor. In the illustrated example, the static elimination device neutralizes the photoconductor 10 and the charging device charges the photoconductor 10. At a subsequent position, a pre-wet device is provided at a position before exposure in the process direction.

The pre-wetting device includes a pre-wet liquid application roller 30 that contacts the photoreceptor 10 to apply a supplied pre-wet liquid film to the surface of the photoreceptor, and pre-wet liquid from a reservoir (not shown). Rollers 31 and 32 for supplying the liquid application roller 30 are provided.
As described above, by adopting a configuration in which the pre-wet liquid is applied before exposing the photoreceptor 10, good image quality can be obtained without disturbing the latent image.

FIG. 4 is a view showing a third example of a configuration in which a pre-wet liquid is applied onto a photoreceptor. In the illustrated example, a static eliminator for neutralizing the photoconductor 10 is provided, but a single charging device is not provided. Thereafter, a pre-wet device is provided at a position before exposure in the process direction.

The pre-wetting device is similar to the above-described example.
It has a pre-wet liquid application function of applying the supplied pre-wet liquid film to the surface of the photoreceptor. In the illustrated example, in addition to this function, it has a photoreceptor charging function. That is, the high-pressure D
The C voltage and the AC bias voltage are applied together, so that the photoconductor can be charged.

FIG. 5 is a diagram showing a fourth example of a configuration in which a pre-wet liquid is applied onto a photoreceptor. In the illustrated example, a charging device for charging the photoconductor 10 is provided, but a single static elimination device is not provided.

A pre-wet device is provided at a position before exposure in the process direction and further at a position before charging. The pre-wet apparatus has a pre-wet liquid application function of applying a film of the supplied pre-wet liquid to the surface of the photoconductor similarly to the above-described example. And has a photoconductor neutralization function. That is, a high-frequency AC bias voltage is applied to the pre-wet liquid application roller 30, whereby the photosensitive member can be neutralized.

FIG. 6 is a diagram showing a fifth example of a configuration in which a pre-wet liquid is applied onto a photoreceptor. In the illustrated example, the pre-wet liquid application roller 30 is formed of a rubber roller having fine mesh-like irregularities on its surface, that is, a patterned roller, for example, an anilox type rubber roller made by Asahi Roller. A blade is provided on the rubber roller for scraping off excess pre-wet liquid. By using such a roller, it becomes possible to supply a pre-wet liquid having a uniform and stable layer thickness onto the photoreceptor 10.

FIG. 7 is a diagram showing a sixth example of a configuration in which a pre-wet liquid is applied on a photoreceptor. In the illustrated example, the pre-wet liquid application roller 30 is constituted by a rubber roller having a smooth surface, and the pre-wet liquid supply roller 31 which is in contact with the rubber roller is a conductive roller having mesh-like fine irregularities on the surface. , For example, an anilox type metal roller.
Further, another supply roller 32 is provided on the conductive roller.
And a blade for scraping off excess pre-wet liquid. By using such a roller, it is possible to supply a prewetting liquid having a uniform and stable layer thickness onto the photoreceptor 10.

By grounding the conductive roller 31, it is possible to prevent surface charging of the pre-wet liquid supply roller and to eliminate static electricity.

FIG. 8 is a view showing a seventh example of a configuration in which a pre-wet liquid is applied on a photoreceptor. As shown,
A blade support is provided, and a blade is attached to a lower surface of the blade support so as to further extend from a tip end thereof. The blade is a plate-shaped spring having a width substantially equal to the width of the developing roller and having a small spring constant, and can be made of, for example, urethane. As shown, the blade is brought into contact with the rotating photoreceptor 10 such that the applied pre-wet liquid is separated from the tip of the blade.

The blade support has substantially the same width as the blade and therefore the photoreceptor 10, and has a plurality of slits or holes arranged in the width direction. The slit or hole penetrates the photoreceptor 10 in a circumferential direction so as to supply a pre-wet liquid, and the pre-wet liquid can be supplied to the surface of the photoreceptor 10 through the slit or hole. FIG. 9 shows FIG.
FIG. 3 is a view illustrating only the blade support shown in FIG. When a slit is provided as shown in the figure, the pre-wet liquid flows out of the reservoir through the slit and is supplied to the surface of the blade opposite to the surface facing the photoreceptor, from which it is supplied to the photoreceptor along the blade surface. Is done. With such a configuration, the pre-wet liquid poured onto the blade can be thinly and uniformly applied onto the photoreceptor by the blade.

[0042]

According to the present invention, in consideration of the recycling of the liquid toner, the same prewetting liquid as the liquid toner carrier liquid is used, and the viscosity of the prewetting liquid is reduced to reduce the fog on the image. be able to.

Further, according to the present invention, after exposing the photoreceptor,
By adopting a configuration in which a pre-wet liquid is applied, good image quality can be obtained without disturbing the latent image, and the configuration of the photoconductor charge eliminating mechanism and the photoconductor charging mechanism can be simplified.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a liquid development type electrophotographic apparatus embodying the present invention.

FIG. 2 is a diagram illustrating a first example of a configuration in which a pre-wet liquid is applied onto a photoreceptor.

FIG. 3 is a diagram illustrating a second example of a configuration in which a pre-wet liquid is applied on a photoreceptor.

FIG. 4 is a diagram showing a third example of a configuration in which a pre-wet liquid is applied on a photoreceptor.

FIG. 5 is a diagram showing a fourth example of a configuration in which a pre-wet liquid is applied on a photoreceptor.

FIG. 6 is a diagram illustrating a fifth example of a configuration in which a pre-wet liquid is applied onto a photoreceptor.

FIG. 7 is a view showing a sixth example of a configuration in which a pre-wet liquid is applied onto a photoreceptor.

FIG. 8 is a view showing a seventh example of a configuration in which a pre-wet liquid is applied onto a photoreceptor.

FIG. 9 is a view illustrating only the blade support shown in FIG. 8 by taking it out;

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 photosensitive drum (photosensitive member) 11 first photosensitive drum 12 second photosensitive drum 13 third photosensitive drum 14 fourth photosensitive drum 15 intermediate transfer roller 16 intermediate transfer belt 18 heat roller 19 pressure roller 30 pre-wet liquid Coating roller 31 Supply roller 32 Supply roller 33 Reservoir with heater 40 Developing roller 41 Applicator roller 42 Applicator roller

Continuing from the front page (72) Inventor Shigenori Uesugi 98, Unoki-nu, Unoki-cho, Kawakita-gun, Ishikawa Pref. (72) Inventor Satoru Hongo 98, Unoki-nu, Unoki-cho, Kawakita-gun, Ishikawa PFU Co., Ltd. (72) Inventor Genji Ichikawa 98, Unoki-cho, Unoki-cho, Hebei-gun, Ishikawa 2 PFU-Co., Ltd. (72) Masataka Takahata 98, Unoki-nu, Unoki-cho, Kawakita-gun, Ishikawa 2 PFU Co., Ltd. (72) Inventor Shigeharu Okano 98 Unoki Nu, Unoki-cho, Kawakita-gun, Ishikawa Prefecture 2 Pfu Co., Ltd. (72) Yasukaichi Takeda 98 Uno Unu, Unoki-cho, Kawakita-gun, Ishikawa Prefecture (72) Inventor Tadashi Nishikawa 98 Unouki-nu, Unoki-cho, Kawakita-gun, Ishikawa Pref. 2 Inventor Satoshi Miyamoto Satoshi Miyamoto 98 Uno-nu, Unoki-cho, Kawakita-gun, Ishikawa No.2 PF Yu Co., Ltd. -Inside (72) Inventor Kazushi Terashima 98 Unoki-nu, Unoki-cho, Kawakita-gun, Ishikawa Pref. Inside PFU Co., Ltd. Inside PFU (72) Inventor Hironaga Honkawa 98 Unoki-nu, Unoki-cho, Hebei-gun, Ishikawa Prefecture 2 Pfu Co., Ltd. 2 F-term in PF Corporation (reference) 2H035 AA15 AA24 AB02 2H074 AA03 AA07 BB08 BB50 BB61 CC28 3J103 AA02 AA66 BA03 BA46 FA18 FA30 GA02 GA52 HA03 HA20 HA53 4F040 AA05 AB20 BA12 CB06 DB09

Claims (9)

[Claims] 1. An electric field generated between a liquid developer and a liquid developer by supplying the liquid toner in contact with the image support on which an electrostatic latent image is to be formed and the image support. And a pre-wet device for applying a pre-wet layer to the surface of the image support at a position in front of the developing device by adhering toner particles of liquid toner to the image support in accordance with In the liquid developing electrophotographic apparatus provided, the pre-wet apparatus comprises a means for heating and supplying the pre-wet liquid, and a film of the heated pre-wet liquid being brought into contact with the image support and being heated on the surface of the image support. And a pre-wet liquid applying roller for applying the liquid. 2. The liquid developing electrophotographic apparatus according to claim 1, wherein said pre-wet liquid application roller comprises a heat roller. 3. The liquid developing electrophotographic apparatus according to claim 1, wherein the heating of the pre-wet liquid is performed by providing a heater in a pre-wet liquid reserve tank kept warm. 4. An electric field generated between a liquid toner as a liquid developer and a liquid toner supplied on the image support on which an electrostatic latent image is formed by supplying the liquid toner. And a pre-wet device for applying a pre-wet layer to the surface of the image support at a position in front of the developing device by adhering toner particles of liquid toner to the image support in accordance with In the liquid developing electrophotographic apparatus provided, the pre-wet apparatus abuts on the image support at a position before exposure in the process progress direction, and applies the supplied film of the pre-wet liquid to the surface of the image support. A means for applying a high-voltage DC voltage and an AC bias voltage to the pre-wet liquid applying roller in combination with the pre-wet liquid applying roller to charge the image support; Liquid developing electrophotographic apparatus which comprises and a exposing means for on the basis of exposure. 5. An electric field generated between a liquid developer and a liquid developing solution by supplying the liquid toner in contact with an image support on which an electrostatic latent image is to be formed, and the liquid support. And a pre-wet device for applying a pre-wet layer to the surface of the image support at a position in front of the developing device by adhering toner particles of liquid toner to the image support in accordance with In the liquid developing electrophotographic apparatus provided, the pre-wet apparatus abuts on the image support at a position before exposure in the process progress direction, and applies the supplied film of the pre-wet liquid to the surface of the image support. A means for applying an AC bias voltage to the pre-wet liquid applying roller to remove electricity from the image support; a means for charging the image support; and a method for forming the charged image support. A liquid developing electrophotographic apparatus comprising: an exposure unit configured to perform exposure based on image data. 6. The pre-wet liquid applying roller comprises a rubber roller having fine mesh-like irregularities on its surface,
6. The liquid developing electrophotographic apparatus according to claim 1, further comprising a blade for scraping off excess pre-wet liquid on said rubber roller. 7. The pre-wet liquid applying roller is in contact with the pre-wet liquid applying roller, and a pre-wet liquid supply roller provided with fine mesh-like irregularities on its surface, and scrapes excess pre-wet liquid on the supply roller. The liquid developing electrophotographic apparatus according to claim 1, further comprising a blade for removing the liquid. 8. The liquid developing electrophotographic apparatus according to claim 7, wherein the pre-wet liquid supply roller comprises a grounded conductive roller. 9. An electric field generated between a liquid developer as a liquid developer, a liquid toner supplied to the image support on which an electrostatic latent image is to be formed, and the liquid toner supplied to the image support. And a pre-wet device for applying a pre-wet layer to the surface of the image support at a position in front of the developing device by adhering toner particles of liquid toner to the image support in accordance with In the liquid developing electrophotographic apparatus provided, the pre-wet apparatus includes a blade support having a plurality of through slits or through holes arranged in parallel, and a blade attached to a lower surface of the blade support so as to further extend from a tip thereof. The pre-wet liquid is supplied to the image support surface by flowing the pre-wet liquid from the upper surface of the blade to the image support surface through a plurality of through slits or through holes provided in the blade support. Thinly on the body, and uniform liquid developing electrophotographic apparatus for coating.