JP3521975B2 - Liquid developing device for electrostatic latent images - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to electrophotography, electrostatic recording,
The present invention relates to a liquid developing device for an electrostatic latent image that visualizes an electrostatic latent image formed by a method such as ionography using a liquid developer.

[0002]

2. Description of the Related Art Conventionally, in a liquid developing apparatus for an electrostatic latent image, a developer support having a surface coated with a liquid developer is brought into contact with an image support to thereby form a latent image on the image support. Supplying liquid developer. Here, the uniform thickness of the liquid developer supplied to the latent image surface on the image support is an important requirement for making the image density (particularly the image density in the case of solid black) uniform. . Therefore, it is necessary that the liquid developer on the developer support be applied in a uniform thickness. As a method of applying the liquid developer to the surface of the developer support with a uniform thickness, there is a method of applying the liquid developer to the developer support via a roller. In such a method, the thickness of the liquid developer on the roller is regulated by a blade or the like, so that the liquid developer can be applied thinly and evenly on the developer support.

[0003]

However, in the electrostatic latent image liquid developing apparatus using the above method, the excess liquid developer regulated by the blade or the like is moved in the width direction of the roller by the rotation of the roller. May fall from both ends of the roller. As a result, there is a problem that toner stains occur inside the apparatus. There is also a problem that excessive liquid developer adheres to the developer support to cause image noise.

[0004]

[Purpose] The present invention has been made based on the above circumstances, and a liquid developer can be applied thinly and uniformly on a developer support, and excess liquid developer adheres to the developer support. It is an object of the present invention to provide a liquid developing device for an electrostatic latent image that can prevent the occurrence of the above.

[0005]

In order to achieve the above-mentioned object, a liquid developing device for an electrostatic latent image according to the present invention as defined in claim 1 forms an electrostatic latent image formed on an image support, charged with a liquid developing method of the electrostatic latent image is developed by toner as a developing particles, a developer carrier to which the toner in the insulating liquid can carry the liquid developer dispersion, at least two
Liquid on the developer support through two rollers.
And a coating means for coating an image agent, wherein the width of the roller becomes smaller as the coating means approaches the developer support, and the liquid developer has a high concentration of toner in an insulating liquid. 100 to 10,000 mPa dispersed
s of high viscosity.
According to a second aspect of the present invention, in the liquid latent image developing apparatus of the present invention, in the first aspect of the invention, the width of the roller contacting the developer support is the width of the developer support. It is characterized by being smaller.

[0006] Liquid developing unit of an electrostatic latent image of the present invention according to claim 3, in the invention of claim 1 or 2 wherein, prior to
The coating means contacts the developer support of the roller.
The roller is at the bottom.
The electrostatic latent image liquid developing device of the present invention according to claim 4.
Is the invention according to any one of claims 1, 2 and 3.
Of the rollers farthest from the developer support.
Install a guide blade that moves the liquid developer to the center
It is characterized by that.

[0007] Liquid developing unit of an electrostatic latent image of the present invention as set forth in claim 5, in the invention of any one of claims 1, 2, 3, 4, the liquid developing device of the electrostatic latent image , The above
Dielectric liquid with releasability and chemically inert on image support
A pre-wetting means for applying a pre-wetting liquid that is
Developer disposed with a minute gap from the image support.
High concentration of toner dispersed in insulating liquid on support
Apply high-viscosity liquid developer and apply to the developer support
Formed on the liquid support layer and the image support
Image by contacting with a pre-wet liquid layer
Presently, the high-viscosity liquid developer is supplied to the latent image surface of the support.
And image forming means.

The electrostatic latent image liquid of the present invention according to claim 6
The body developing device is defined in any one of claims 1, 2, 3, 4, and 5.
In the invention described above, the insulating liquid of the liquid developer has a viscosity of 0.5 to 1000 mPa · s and an electric resistance of 10 ¹²
Ωcm or more, surface tension is 21 dyne / cm or less, and boiling point is 100 ° C. or more. A liquid developing device for an electrostatic latent image according to a seventh aspect of the present invention is
According to a sixth aspect of the invention, the liquid developer uses silicon oil as an insulating liquid.

According to an eighth aspect of the present invention, there is provided an electrostatic latent image liquid developing apparatus according to the fifth aspect , wherein the liquid developer is an electrostatic liquid. Often
The resistance is 10 ¹² Ωcm or more, the boiling point is 100 to 250 ° C.,
The surface tension is 21 dyne / cm or less.
It is something. Liquid developing unit of an electrostatic latent image of the present invention as set forth in claim 9 is the invention according to claim 8, main component
Use silicone oil as the dielectric liquid
It is characterized by that.

According to a tenth aspect of the present invention, there is provided an electrostatic latent image liquid developing device according to the first, second, third, fourth, fifth, sixth, seventh aspect.
The invention according to any one of Items 8 and 9 is characterized in that the liquid developer contains a toner having an average particle diameter of 0.1 to 5 μm at a concentration of 5 to 40%.

[0011]

A liquid developing device for an electrostatic latent image according to claim 1 is provided with a coating means for coating the liquid developer on the developer support through two or more rollers. Since the layer thickness of the developer is regulated thinly and uniformly at the contact portion with the adjacent roller, the liquid developer can be applied thinly and uniformly on the developer support, and as a result, on the image support. The liquid developer can be uniformly supplied to the latent image surface. Further, by making the width of each roller closer to the developer support, the excess liquid developer supplied to each roller is moved in the width direction of the roller by the rotation of the roller, and then both ends of the roller are moved. It can be conveyed from a section to a roller having a wider width that abuts on the roller. This allows the excess liquid developer to be moved to the roller farther from the developer support, so that the excess liquid developer may drop from both ends of the roller and adhere to the developer support, or It can be prevented from becoming dirty. In addition, Tona
Is the result of using a liquid developer in which the
Compared to conventional low-concentration liquid developers,
Can be reduced. The liquid developer has a viscosity of 100.
If the pressure exceeds 00 mPa · s, the insulating liquid and toner
Stirring becomes difficult and how to make liquid developer
Is a problem. Therefore, 10,000 mPa · s or more
Liquid developer is not realistic because it is not worth the cost.
Become On the other hand, at 100 mPa · s or less, the toner density
Becomes lower and the dispersibility of the toner becomes worse,
The developer cannot be developed in a thin layer for development. 3. The electrostatic latent image liquid developing device according to claim 2, wherein the roller supporting the developer support has a width smaller than that of the developer support, so that the developer support has flexibility. In the case of using the one formed in, the liquid developer located at both ends of the roller that abuts the developer support is prevented from protruding from the developer support and moving to the back surface of the developer support. You can

A liquid developing device for an electrostatic latent image according to claim 3.
The roller that contacts the developer support should be at the bottom.
Can facilitate the supply of the liquid developer provided on the upper side.
By using a liquid developer with a high viscosity,
The rollers from the edge to the top of the roller are unaffected.
Can be transferred to La. Furthermore, according to claim 4,
A liquid developing device for an electrostatic latent image is a roller far from the developer support.
By installing a guide guide in the
The developer can be circulated constantly, and the waste of liquid developer can be avoided.
Can be prevented.

A liquid developing device for an electrostatic latent image according to claim 5.
Is used as a developer layer and pre-wet liquid during the development process.
It is possible to make contact with the layers while maintaining the two-layer state.
Also, at the end of the development process, both
Since the developer is separated, it is possible to prevent the developer layer from being disturbed.
And the toner adheres to the non-image area on the image support.
The image can be prevented from being disturbed, and the toner
A thin layer of highly viscous liquid developer dispersed in high concentration is used.
The image is high resolution and easy to miniaturize.

A liquid developing device for an electrostatic latent image according to claim 6.
By using an insulating liquid having the above characteristics,
A high-viscosity liquid developer can be obtained. Since the liquid developer formed on the developer support is formed in a thin layer,
Since the amount of insulating liquid contained in the liquid developer layer is extremely small, the amount of insulating liquid contained in the liquid developer supplied to the latent image surface of the image support is also very small. Therefore, the amount of the insulating liquid absorbed on the paper or the like at the time of transfer is extremely small, so that the problem of the insulating liquid adhering to the paper or the like does not occur if the viscosity is 1000 mPa · s or less. However, if the viscosity is 0.5 mPa · s or less, the volatility becomes high and it is not suitable as a hazardous material. When the boiling point of the insulating liquid is 100 ° C. or less, the amount of evaporation is large, so that there is a problem in the method of storing the developer, the entire device must have a closed structure, and it is difficult to improve the working environment. . When the electric resistance is 10 ¹² Ωcm or less, the insulating property is deteriorated, and the toner has a problem of conductivity and cannot be used as a developer. Therefore, it is desirable that the electric resistance be as high as possible. Surface tension is 21 dyne / cm
When it is more than the above, the wettability becomes poor. Therefore, it is desirable that the surface tension be as low as possible. Stillness according to claim 7.
In the liquid latent image developing device, since the insulating liquid is mainly composed of silicone oil , the insulating liquid having the characteristics described in claim 6 can be obtained.

A liquid developing device for an electrostatic latent image according to claim 8.
You may use the one before Symbol properties to the dielectric liquid in the pre-wet liquid
By doing so, there is no problem in developing, transferring, and fixing the liquid.
An electrostatic latent image formed on the photoconductor after drying
Easily evaporates during fixing without disturbing the fogging and toner
Do not let the lumps of the toner adhere to the photoconductor to improve the releasability.
To prevent image stains and fogging, and to improve image resolution and fogging.
To improve Liquid development of the electrostatic latent image according to claim 9.
The device has a dielectric liquid mainly composed of silicone oil.
The dielectric having the characteristics according to claim 8
A toxic liquid can be obtained.

A liquid developing device for an electrostatic latent image according to claim 10.
Is a liquid developer with a toner having an average particle size of 0.1 to 5 μm.
By containing it at a concentration of -40%, it is possible to obtain a liquid developer in which the toner is dispersed in the insulating liquid at a high concentration. In addition, the resolution is improved in almost inverse proportion to the particle size of the toner. Usually, the toner is present as a mass of about 5 to 10 pieces on the printed paper, so that when the average particle diameter of the toner becomes 5 μm or more,
The resolution is poor. On the other hand, the average particle size of the toner is 0.1μ
When it is less than m, the physical adhesive strength becomes large and it becomes difficult to peel off the toner during transfer.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 is a schematic configuration diagram of an electrostatic latent image liquid developing device according to an embodiment of the present invention. FIG. 2 is a schematic front view of a developing device used in the electrostatic latent image liquid developing device shown in FIG. 3 is a right side view of the developing device shown in FIG. 2, and FIG.
FIG. 6 is a diagram for explaining the operation of the liquid developing device for the electrostatic latent image shown in FIG.

As shown in FIG. 1, an electrostatic latent image liquid developing apparatus 1 according to an embodiment of the present invention applies a photoconductor 10 as an image support and a prewetting liquid on the photoconductor 10. A pre-wetting device 20, a charging device 30 that charges the photoconductor 10, and an exposure device 40 that exposes an image on the photoconductor 10.
And a developing device 50 that visualizes the electrostatic latent image by supplying toner to the portion of the photoconductor 10 on which the electrostatic latent image is formed.
A transfer device 60 for transferring and fixing the toner image on the photoconductor 10 to a predetermined paper P, a cleaning device 70 for removing the toner remaining on the photoconductor 10, and a charged photoconductor (not shown). A static eliminator for static eliminating the body 10 is provided.

For the charging device 30, the exposure device 40, the cleaning device 70, and the static eliminator, the conventional technique used in the conventional electrophotographic printer can be used in most cases. Therefore, in the present embodiment, the description of each of the above devices will be omitted, and the pre-wetting device 20, the developing device 50, and the transfer device 60, which are the main parts of the present invention, will be described.

The function required of the pre-wetting device 20 of this embodiment is to apply a constant amount of the pre-wetting liquid onto the photoconductor 10 uniformly. For that purpose, a method of applying the pre-wetting liquid with a sponge-like material,
A coating method for other purposes such as a method of ejecting the pre-wetting liquid from a plurality of nozzles arranged in the width direction of the photoconductor 10 or a method of applying the pre-wetting liquid with a sponge roller can be used. The inventors of the present invention tried various methods and confirmed that the above method was possible. The most convenient and best-performing method was to use a pre-wetting liquid using BELITA (registered trademark: Kanebo Co., Ltd.). Was the method of applying. The bell eater is a continuous porous body having a three-dimensional network structure in which pores are continuous, can hold the pre-wet liquid by the volume of the pores, and when the pre-wet liquid exceeding the volume of the pores is supplied, The wetting liquid can be uniformly discharged from the surface. still,
The bell eater used in this embodiment has a substantially semi-cylindrical contact surface with the photoconductor 10.

As shown in FIGS. 2 and 3, the developing device 50 comprises a developing section 51 and a coating section 52.
The developing section 51 includes a developing belt 510 that is a developer support.
Drive rollers 512a and 512b for rotating and driving the developing belt 510 and holding a portion of the developing belt 510 in contact with the photoconductor 10, and the developing belt 51.
Scraping blade 5 for removing the liquid developer remaining at 0
14 and 514. The coating unit 52 is the developing belt 5
Application parts 52a, 52 for applying a liquid developer to the surface of
b, 52c, 52d are included.

The developing belt 510 includes a driving roller 512.
It is rotationally driven in the direction in which the photoconductor 10 is driven by a and 512b. As the developing belt 510, a flexible belt member such as a seamless nickel belt or a resin belt such as a polyimide belt is used. The developing belt 510 must be capable of applying a developing bias. Therefore, when a resin belt is used, it is necessary to reduce the electric resistance value by subjecting the surface of the belt to conductive processing or adding conductive fine particles to the material of the belt.

The coating parts 52a to 52d store and discharge the liquid developer, and a conveying roller 522a, 522b, 5 for conveying the liquid developer discharged by the bellows pump 520 to the developing belt 510.
22c and 522d, a pair of arms 524 and 524,
A pair of guide blades 528 and 528 are provided at both ends of the transport roller 522a. Liquid developer containing yellow toner is applied to the bellows pump 520a of the application section 52a, liquid developer containing magenta toner is applied to the bellows pump 520b of the application section 52b, and cyan toner is applied to the bellows pump 520c of the application section 52c. Of the liquid developer, and the bellows pump 520 of the applying portion 52d.
A liquid developer containing black toner is stored in each d.

The carrying roller 522d is a carrying roller 522c.
The transport roller 522c is configured to contact the transport roller 5
22b so that it abuts against the transport roller 522b.
Are provided so as to contact the transport rollers 522a. The carrying roller 522d is in the direction to follow the developing belt 510, and the carrying roller 522c is the carrying roller 522.
d, the transport roller 522b is driven by the transport roller 522c, and the transport roller 522c is driven by the transport roller 522c.
a rotates in the direction in which it is driven by the transport roller 522b.

As shown in FIG. 3, the widths of the carrying rollers 522a to 522d are from the carrying roller 522a to the carrying roller 5 as shown in FIG.
It becomes shorter in the order of 22d, and the conveying roller 522d is the shortest. Thereby, for example, the excess liquid developer supplied to the transport roller 522d is transferred in the width direction of the transport roller 522d by the rotation of the transport roller 522d, and then transported to both ends of the transport roller 522d to the transport roller 522c. . After that, the liquid developer transported to the transport roller 522c is transferred in the width direction of the transport roller 522c by the rotation of the transport roller 522c, and then transported to the transport roller 522b from both ends of the transport roller 522c. And
The liquid developer transported to the transport roller 522b is finally transferred to the transport roller 522b by the rotation of the transport roller 522b.
After being transferred in the width direction of b, it is transported to the transport roller 522a from both ends of the transport roller 522b. In this way, the width of the transport rollers 522 a to 522 d is set to the developing belt 510.
The closer to
The excess liquid developer supplied to b to 522d can be transported to the transport roller 522a which is the farthest from the developing belt 510. Further, since the width of the carrying roller 522d is smaller than the width of the developing belt 510, the carrying roller 522d is
It is possible to prevent the liquid developers located at both ends of the developer from protruding from the developing belt 510 and moving to the back surface of the developing belt 510. The liquid developer transported to the transport roller 522a is moved from both ends of the transport roller 522a to the central portion by a pair of guide blades 528 and 528, and then to the transport roller 522d via the transport rollers 522b and 522c. Be transported. As a result, the excess liquid developer can be constantly circulated.

The pair of arms 524 and 524 are rotatably attached to both ends of the shaft of the conveying roller 522c. In addition, the arms 524 and 524 include the transport roller 52.
Both ends of the 2d shaft are rotatably attached. The pair of arms 524 and 524 rotate about the axis of the transport roller 522c by a drive device (not shown).
As a result, the coating roller 522d is brought into contact with and separated from the developing belt 510.

The transfer device 60 includes an intermediate transfer belt 610, which is an intermediate transfer member, and a drive roller 612 a for rotating and driving the intermediate transfer belt 610 and holding a part of the intermediate transfer belt 610 so as to contact the photosensitive member 10. 612
b, 612c, and a secondary transfer roller 61 which is a secondary transfer member installed so as to be in contact with the intermediate transfer belt 610.
4 and a scraping blade 616 for removing the toner remaining on the intermediate transfer belt 610.

The intermediate transfer belt 610 includes a driving roller 61.
2a, 612b, 612c are driven to rotate in the direction in which the photoconductor 10 is driven. The secondary transfer roller 614 is pressed against the intermediate transfer belt 610 via the paper P. The fixing heater 6 for heating the paper P is provided inside the driving roller 612c.
18 is provided.

Next, the image forming material used in one embodiment of the present invention will be described. The liquid developer used in this example includes a resin that serves as a binder such as epoxy, a charge control agent that gives a predetermined charge to the toner, a color pigment, a toner that includes a dispersant that uniformly disperses the toner, and a carrier liquid. Consists of. The toner composition is basically similar to that used in conventional liquid developers, but their formulation has been modified to be compatible with silicone oils for adjusting charging characteristics and dispersibility. The smaller the average particle size of the toner is, the better the resolution is. However, the smaller the particle size is, the larger the physical adhesive force is, and the more difficult it is to remove when transferring. Therefore, in this embodiment, the average particle diameter of the toner is adjusted so that the center is around 2 to 4 μm for the purpose of improving transferability.

The viscosity of the liquid developer depends on the carrier liquid used,
It depends on the resin, color pigment, charge control agent, etc. and their concentrations. In this example, the viscosity is 50 to 6000 m.
An experiment was conducted by changing the Pa · s and the toner concentration within the range of 5 to 40%.

As the carrier liquid, one having a low viscosity such as dimethylpolysiloxane oil or cyclic polydimethylsiloxane oil exhibiting high electric resistance is used. Incidentally, the developing belt 510
Since the liquid developer layer formed thereon is formed in a thin layer, the carrier liquid contained in the liquid developer layer is extremely small. Therefore, the amount of carrier liquid contained in the liquid developer supplied to the latent image surface of the photoconductor 10 is also extremely small, so that the amount of carrier liquid absorbed by the paper or the like during transfer is extremely small. Therefore, the viscosity is 1000 mPas
If it is below, almost no carrier liquid remains after fixing.

According to the experiments conducted by the present inventors, when the image output experiment was conducted using DC344 of Dow Corning Co., USA having a viscosity of 2.5 mPa · s as the carrier liquid, the carrier remaining on the paper after fixing was determined. No liquid was seen. But,
Due to its high volatility, it was necessary to make the developing device a closed structure. In addition, when the image output experiment was conducted using DC345 of Dow Corning Co., USA, which has a viscosity of 6.5 mPa · s as the carrier liquid, it was fixed on paper after fixing similarly to the case where the image output experiment was conducted using DC344. No carrier liquid remained in the. However, since the volatility is high, it is necessary to make the developing device have a closed structure. Furthermore, the carrier liquid has a viscosity of 20 mPas, Shin-Etsu Silicon KF-96
When the image output experiment was carried out using -20, no carrier liquid remained on the paper after fixing. Further, since the volatility is not so high, it is not necessary to make the developing device have a closed structure. DC344, DC345 and KF-
96-20 is generally used for cosmetics and has high safety such as toxicity. There are many kinds of carrier liquids such as KF9937 manufactured by Shin-Etsu Silicon Co., Ltd., and any one may be selected as long as the electric resistance, the evaporation property, the surface tension, the safety and the like are satisfied.

Further, in an experiment conducted by the present inventors, when the surface tension is large, fogging or a lump of toner occurs on the photoreceptor 10.
21 dyne / cm experimentally
From the above, it was found that the problem of image quality is likely to occur.

The electric resistance value is preferably 10 ¹⁴ Ωcm or more because of the problem of toner charging stability. At least 10 ¹² Ωcm or more is necessary. In the description of the present embodiment, in view of these experimental results, an example using the DC345, which is low in price and easy to obtain, will be described.

The pre-wetting liquid easily evaporates during fixing without disturbing the electrostatic latent image formed on the photoconductor 10,
It is required that the fog and the lump of toner do not adhere to the photoconductor 10. As an example, DC344, DC200-0.65, -1.0,-, manufactured by Dow Corning, USA
2.0, Shin-Etsu Silicon KF96L-1, KF993
7 etc. are mentioned. Generally, it is necessary to select a highly evaporative silicone oil.

In the experiment conducted by the present inventors, the liquid was dried by development, transfer and fixing without any problem when the liquid viscosity was in the range of 0.5 to 3 mPa · s, but from 5 mPa · s to 6 m
At about Pa · s, there was a tendency that a time and a temperature were required for drying the liquid at the time of fixing. If it is 10 mPa · s, the energy required for drying becomes too large, which is not general. Further, if it is 0.5 mPa · s or less, the volatility becomes high, so that it is regarded as a hazardous material and is not suitable. In addition, the boiling point needs to be 250 ° C. or lower because of the effect of heating the paper.

The surface tension eliminates the adhesive force between the liquid developer and the photoconductor 10 and improves the releasability to prevent image stains and fogging, and also improves the resolution of image quality and fogging.
It should be as low as possible. According to experiments conducted by the present inventors, the limit is about 20 to 21 dyne / cm, and it is necessary to select one lower than this.

When the electric resistance is low, the insulating property deteriorates and electric charges are leaked. Therefore, it is necessary to use the highest possible one. Experimentally, about 10 ¹⁴ Ωcm or more is desirable. A minimum of 10 ¹² Ωcm is necessary.

Next, the operation of the electrostatic latent image developing device according to the first embodiment of the present invention will be described. First, FIG. 4 (A)
As shown in, the charging device 30 charges the photoconductor 10. Generally, a corona discharger is used for the charging device 30. Next, the image is exposed on the charged photoreceptor 10. For example, the image is exposed by a laser scanner to expose the photoreceptor 10.
To form an electrostatic latent image on the surface of. As shown in FIG. 4B, the portion of the laser scanner exposed to the light becomes conductive, so that the charge disappears, and the portion not exposed to the light remains as an electrostatic latent image which is an image of the charge.

Next, as shown in FIG. 4C, the above-mentioned pre-wetting liquid is applied onto the photoconductor 10 by the pre-wetting device 20.

Next, the electrostatic latent image is visualized by the developing device 50. Transport roller 522 by bellows pump 520
The liquid developer discharged to the contact start position between a and the transport roller 522b is regulated to have a uniform thickness by the contact portion between the adjacent transport rollers and is thinly and evenly applied to the surface of the developing belt 510. Thereby, a thin layer of the liquid developer can be formed on the developing belt 510. Developing device 50
Rotates a pair of arms 524 and 524 provided on each of the coating sections 52a to 52d to bring one of the coating sections 52a to 52d into contact with the developing belt 510.
As a result, the liquid developer containing the toner of any one of yellow, magenta, cyan, and black can be thinly and evenly applied onto the developing belt 510.
The excess liquid developer supplied onto the carrying rollers 522b to 522d is transferred in the width direction of the carrying roller by the rotation of the carrying roller, and then the carrying roller 522a farthest from the developing belt 510 from both ends of the carrying roller. Be transported to.

Next, the liquid developer layer formed on the developing belt 510 is brought close to the electrostatic latent image formed on the surface of the photoconductor 10 as shown in FIG. As a result, the charged toner is moved onto the photoconductor 10. As a result, a toner image is formed on the photoconductor 10.

Next, as shown in FIG. 4E, the toner image formed on the developing belt 510 is primarily transferred onto the intermediate transfer belt 610 by the transfer device 60. On the other hand, the photoconductor 10 has the liquid developer remaining on the photoconductor 10 removed by the cleaning device 70, and then the charge removed by a charge removal device (not shown).

Next, by rotating a pair of arms 524 and 524 provided on each of the coating sections 52a to 52d, the coating sections 52a to 52d contacting the developing belt 510 are switched. Then, by repeating the cycle from the charging to the discharging again, the yellow, magenta, cyan, and black toner images are transferred one after another onto the intermediate transfer belt 610. As a result, a toner image corresponding to colorization is formed on the intermediate transfer belt 610.

Next, as shown in FIG. 4 (F), the toner image corresponding to colorization formed on the intermediate transfer belt 610 by the transfer device 60 is secondarily transferred onto the paper P which is a recording medium and fixed at the same time. To do. The toner image corresponding to the color formed on the intermediate transfer belt 610 is printed on the paper P by the pressing force of the secondary transfer roller 614 which is in contact with the intermediate transfer belt 610 to the intermediate transfer belt 610 and the heat of the fixing heater 618. And is secondarily transferred, and at the same time is thermally fused and fixed. Thereby, a color image can be formed on the paper P. The intermediate transfer belt 610 is thereafter cleaned by a scraping blade 616 that comes in contact with and separates from the intermediate transfer belt 610.

5 to 9 are views for explaining the developing process of one embodiment of the present invention in detail, FIG. 5 is a diagram for explaining the whole developing process, and FIG. 6 is a state of the approaching process. FIG. 7 is a diagram showing a state of toner movement process, and FIG.
FIG. 9 is a diagram showing how the non-image portion is separated, and FIG. 9 is a diagram showing how the image portion is separated. Unlike the conventional developing process, in the developing process of the present embodiment, the developing belt 510 approaches the photoconductor 10 and the liquid developer approaches the surface of the photoconductor 10, as shown in FIG. The toner moving process in which the developer layer and the pre-wet liquid layer are in soft contact to move the toner, and the developing belt 510 is separated from the photoconductor 10 and adheres to the developing belt 510.
It is considered to be composed of three processes, that is, a separation process in which the toner adheres to 0 and a separation process.

In the approaching process, since the developing belt 510 is made of a flexible belt member, as shown in FIG. 6, the liquid developer layer on the developing belt 510 and the photosensitive member 1 are made.
The contact pressure at the time of contact with the pre-wet layer above 0 is dispersed, and the high-viscosity liquid developer consisting of the carrier liquid and the toner is soft-contacted with the pre-wet liquid. As a result, the pre-wet liquid having a low viscosity is slightly pushed back and forth, and a liquid pool of the pre-wet liquid is generated.

During the toner movement process, as shown in FIG. 7, in the image portion, the toner on the developing belt 510 is mainly caused by the Coulomb force due to the electric field formed between the charges on the photoconductor 10 and the developing belt 510. It passes through the pre-wet liquid layer and moves to the latent image surface. On the other hand, in the non-image portion, the toner on the developing belt 510 has the surface of the photoconductor 10 and the liquid developer layer separated by the pre-wet liquid layer.
It does not move to the surface of the photoconductor 10.

In the separation process, in the non-image part, as shown in FIG.
As shown in, the liquid developer remains on the developing belt 510. 2 at the interface between the pre-wet liquid layer and the liquid developer layer
When the two layers are separated, a part of the pre-wet liquid layer having a low viscosity is transferred to the liquid developer layer and separated. Therefore,
The separation point of the two layers is considered to be inside the pre-wet liquid layer. On the other hand, in the image portion, as shown in FIG. 9, the toner that has moved to the surface of the photoconductor 10 pushes away the pre-wet liquid layer, so that the pre-wet liquid layer is located on the toner layer, and both are in the pre-wet liquid layer. Separate inside. On the developing belt 510, a part of the carrier liquid remaining after the toner is moved and a part of the pre-wetting liquid form a layer.

FIG. 10 is a diagram for explaining the significance of thinning the liquid developer. If the liquid developer layer applied on the developing belt 510 is too thick, the viscosity of the liquid developer is high, so that the electrostatic force can cause the developing belt 510 to move to the photoreceptor 1.
The toner group that is about to move to the surface of 0 forms a cluster without breaking the viscosity of the toner located around it and moves to the surface of the photoconductor 10. For this reason, the toner excessively moves, the toner image formed on the photoconductor 10 is disturbed, and image noise occurs. In order to suppress the generation of these clusters, it is necessary to control the layer thickness of the liquid developer layer to a minimum value that allows sufficient development.

FIG. 11 is a view showing a state in which the developing roller formed of a rigid body which is a developing support and the photoconductor 10 are in hard contact, and FIG. 12 is a diagram for explaining the soft contact of this embodiment. Is. As described above, the function of the pre-wet liquid layer for image formation is important in the developing process of this embodiment. Therefore, the important requirements in the development process are the prewetting liquid layer and the liquid developer layer.
It is to maintain the state of layers. As shown in FIG. 11, when the developing roller and the photoconductor are in hard contact with each other, the two-layer state cannot be maintained. Therefore, in this embodiment, as shown in FIG. By using the developing belt 510 including the belt member having the prewetting liquid layer, the prewetting liquid layer on the photoconductor 10 and the liquid developer layer on the developing belt 510 are dispersed by the contact pressure being dispersed. The two layers of the liquid developer layer and the liquid developer layer are maintained.

Next, the layer thickness of the liquid developer layer on the developing belt 510 and the layer thickness of the pre-wet liquid layer on the photoconductor 10 will be described. The layer thickness of the liquid developer layer on the developing belt 510 needs to be thin when the viscosity of the liquid developer is 50 to 100 mPa · s or more, particularly 500 mPa · s or more. Ideally, it should be slightly thicker than the layer thickness that satisfies the toner development amount (that is, the density when solid black is produced) required at the time of development. This is because when a high-viscosity liquid developer is used, the electrostatically selected toner moves to the photoconductor 10 along with the extra toner due to the viscosity of the liquid during development.
This is because the toner image formed on the image surface 0 is disturbed.
In an experiment conducted by the inventors, a good image was obtained with a layer thickness of about 5 μm for a liquid developer having a high toner concentration and with a layer thickness of about 40 μm for a liquid developer having a low toner concentration. In particular, when a liquid developer having a toner concentration of 20 to 30% was used, good image quality was obtained when the layer thickness of the liquid developer was 8 to 20 μm.

The layer thickness of the pre-wet liquid layer on the photoconductor 10 has an optimum value depending on the viscosity and surface tension of the selected pre-wet liquid. If it is too thin, the development belt 51
The toner on 0 moves irregularly on the photoconductor 10 and disturbs the toner image formed on the photoconductor 10. As the amount of the pre-wet liquid is increased, the disorder of the toner image is improved, and the optimum value is confirmed. When the amount is further increased, the toner on the photoconductor 10 flows and the toner image on the photoconductor 10 tends to be blurred. In the experiment using DC344, good results were obtained at a thickness of 30 μm or less, particularly 20 μm or less. For those with lower viscosity,
From this result, good results can be obtained even if the thickness is thin or thick.
However, for high viscosity ones, the optimum value tends to have a narrow range.

As a result of conducting an image development experiment under the above-mentioned conditions, the optimum range of the liquid developer and the viscosity of the pre-wet liquid for the electrostatic latent image developing apparatus of this embodiment is 100 mPa. s to 6000 mPa · s, and the pre-wet liquid was found to be between 0.5 mPa · s and 5 mPa · s. The silicone oil of the pre-wet liquid is DC200 series manufactured by Dow Corning, and the carrier liquid of the developing liquid is DC345 of the same company.
Was used.

According to this embodiment, the transport rollers 522a ...
By providing the application portions 52a to 52d for applying the liquid developer on the developing belt 510 via the 522d, the layer thickness of the liquid developer on each of the transport rollers 522a to 522d is the contact portion between the adjacent transport rollers. The liquid developer can be thinly and uniformly applied on the developing belt 510, and thus the liquid developer can be uniformly supplied to the latent image surface on the photoconductor 10. .

Further, according to this embodiment, the transport roller 52
As the width of 2a to 522d is closer to the developing belt 510,
By making it smaller, the transport rollers 522b to 522d
Excess liquid developer supplied to, after being moved in the width direction of each conveying roller by the rotation of the conveying roller, is conveyed to the conveying roller having a larger width from abutting each conveying roller from both ends of each conveying roller, Finally, it can be transported to the transport roller 522a. As a result, it is possible to prevent the excess liquid developer from falling from both ends of the carrying roller, and thus it is possible to prevent the inside of the apparatus from being soiled with the toner. In addition, it is possible to prevent the excess liquid developer from adhering to the developing belt 510 and causing image contamination.
Further, it is possible to prevent the liquid developer on the developing belt 510 from being mixed with each other.

Further, according to this embodiment, the transport roller 5
By making the width of 22d smaller than the width of the developing belt 510, the liquid developers located at both ends of the conveying roller 522d protrude from the developing belt 510 and the developing belt 51.
It can be prevented from moving to the back surface of 0 and adhering. As a result, the liquid developer adheres to the drive rollers 512a and 512b and the developing belt 510 slips,
Further, it is possible to prevent the liquid developer adhering to the back surface of the developing belt 510 from solidifying and causing a running problem.

Furthermore, according to the present embodiment, since silicon oil is used as the carrier liquid for the liquid developer,
It has the following advantages over conventional ones.

Conventional liquid developers generally use IsoparG (registered trademark: manufactured by Exxon) as a carrier liquid.
Since this Isopar has a resistance value not as high as that of silicone oil, when the toner concentration is increased, that is, when the distance between particles is reduced, the chargeability of the toner is deteriorated. Therefore, Isop
In the case of ar, the toner density is limited. On the contrary,
Since the silicone oil used in this embodiment has a sufficiently large resistance value, the toner concentration can be increased. Also,
Generally, in the case of Isopar, the toner is well dispersed, and therefore even if the toner concentration is 1 to 2%, the toners repel each other, so that the toner is uniformly dispersed. On the other hand, silicone oil has a toner concentration of 1 to 2%,
The dispersibility is not good and it will precipitate soon. However, when the toner concentration is set to 5 to 40%, the toner is densely packed and stably dispersed. Therefore, in this embodiment, a high-viscosity liquid developer in which toner is dispersed at high density is used. As a result, the amount of the developer can be significantly reduced as compared with the conventional low-concentration liquid developer, and the device can be downsized. Furthermore, since the liquid developer of this embodiment is a high-viscosity liquid, it is easier to store and handle than the conventional low-viscosity liquid developer or powder developer.

Isopar used in the conventional liquid developer is
As mentioned above, it is highly volatile and emits a foul odor,
There is a problem that it not only deteriorates the work environment but also causes pollution. On the other hand, the silicone oil used in this example is a safe liquid and is odorless, as is clear from the fact that it is used for cosmetics. The environment can be improved and pollution problems do not occur.

The present invention is not limited to the above embodiments, but various modifications can be made within the scope of the gist thereof.
For example, in the above-described embodiment, the application section is described in which the liquid developer is applied onto the developing belt 510 via the transport rollers 522a to 522d, but the present invention is not limited to this. The application unit may be one that applies the liquid developer onto the developing belt 510 via at least two rollers.

Further, in the above embodiment, the application portion 52a for applying the liquid developer containing the yellow toner to the developing belt 510 and the application portion 52b for applying the liquid developer containing the magenta toner to the developing belt 510. , The coating portion 52c for coating the developing belt 510 with the liquid developer containing cyan toner and the coating portion 52d for coating the developing belt 510 with the liquid developer containing black toner have been described. Is not limited to this. It suffices that at least one coating section for coating the liquid developer containing the toner of the desired color on the developing belt 510 is provided as necessary.

Further, in the above-mentioned embodiment, the developing belt 510 composed of a flexible belt member is used as the developer support, but the present invention is not limited to this. . The developer support may be an elastic roller formed of an elastic body, a rigid roller formed of a conductive member such as metal, or the like. However, when a rigid roller is used as the developer support, since the rigid roller and the image support are brought into contact with each other without crushing the liquid developer layer formed on the rigid roller, the belt having flexibility to the image support. It is necessary to use an image support belt composed of members, or when a rigid roller and an image support are brought into contact with each other, a minute gap, that is, a gap is formed therebetween.

Further, in the above embodiment, the case where the organic photoconductor 10 is used as the image support has been described, but the present invention is not limited to this. The image support is
Various photoconductors used in the Carlson method, those in which an insulating layer is formed on a conductor that directly forms an electrostatic latent image such as ionography, and electrostatic recording paper such as an electrostatic plotter may be used.

Further, in the above embodiment, as a transfer device, the toner image formed on the photoconductor 10 is primarily transferred onto the intermediate transfer belt 610 which is an intermediate transfer member, and then primary transferred onto the intermediate transfer belt 610. Although the image is formed on the paper P by secondarily transferring the formed toner image onto the paper P, the present invention is not limited to this, and the transfer device is not limited to the image support. Any toner can be used as long as it can transfer the toner image formed on the recording medium. For example, in a monochrome liquid developing device, the toner image formed on the image support may be directly transferred onto a recording medium without primary transfer onto the intermediate transfer member.

In the above embodiment, the image was exposed on the image support charged by the exposure device 40, and then the pre-wet liquid was applied on the image support by the pre-wetting device 20. However, the present invention is not limited to this, and the application of the pre-wetting liquid may be performed before the developing step. In addition, the pre-wet liquid contains silicone oil as a main component if the viscosity is 0.5 to 5 mPa · s, the electric resistance is 10 ¹² Ωcm or more, the boiling point is 100 to 250 ° C., and the surface tension is 21 dyne / cm or less. It does not have to be a thing. Further, when the surface of the image support is coated with a material having releasability, a pre-wetting step is not particularly required.

The present invention is not limited to the above embodiment, and the viscosity of the highly viscous developer may be 10,000 mPa · s as long as the layer thickness of the liquid developer is about 5 to 40 μm. . At present, a developer with a high viscosity of 6000 mPa · s or more is difficult to agitate between the carrier liquid and the toner, so it is thought to be costly. However, if it becomes available at a low cost, it will be even at 6000 mPa · s or more. Good. If the viscosity exceeds 10,000 mPa · s, it becomes unrealistic. Further, the carrier liquid of the liquid developer is not limited to silicone oil.

[0068]

As described above, according to the first aspect of the present invention, by providing the application means for applying the liquid developer on the developer support through the two or more rollers, each roller is provided. Since the layer thickness of the liquid developer can be regulated thinly and uniformly at the abutting portion with the adjacent roller, the liquid developer can be thinly and uniformly applied on the developer support. The liquid developer can be uniformly supplied to the latent image surface on the support, and the width of each roller is made smaller toward the developer support so that the excess liquid development supplied to each roller can be achieved. The agent can be conveyed from both ends of each roller to a roller having a wider width that abuts the roller, and finally can be moved to the roller farthest from the developer support, so that the excess liquid developer can be transferred to the roller. From falling from both ends of the It is possible to prevent the excess liquid developer from dropping from both ends of the roller and adhering to the developer support, thereby preventing image noise from occurring. Especially in the electrostatic latent image liquid developing device equipped with rollers corresponding to each color,
It is possible to provide a liquid developing device for an electrostatic latent image capable of preventing the liquid developer on the developing support from being mixed with each other. Furthermore, a highly viscous liquid in which toner is dispersed in high concentration
By developing the developer in a thin layer for development, high resolution and small
An electrostatic latent image that can be easily modeled and has low pollution
A liquid developing device can be provided.

According to the second aspect of the invention, the width of the roller contacting the developer support is made smaller than the width of the developer support, so that the developer support is formed of a flexible belt member. It is possible to prevent the liquid developer located at both ends of the roller that is in contact with the developer support from protruding from the developer support and moving to the back surface of the developer support when the above-mentioned developer is used. , As a result, the liquid developer adheres to the drive roller that rotationally drives the developer support, causing the developer support to slip, or the liquid developer adhering to the back surface of the developer support solidifying to cause a running problem. It is possible to provide a liquid developing device for an electrostatic latent image that can prevent the occurrence of

A liquid developing device for an electrostatic latent image according to claim 4.
Smoothly supplies the liquid developer to the developer support.
Claim of the inside of the device of liquid developer from the end
The electrostatic latent image liquid developing device described in No. 4 is located far from the developer support.
By installing a guide guide on the roller,
Liquid developer can be constantly circulated, liquid developer
It is possible to prevent waste.

A liquid developing device for an electrostatic latent image according to claim 5.
Is used as a developer layer and pre-wet liquid during the development process.
It is possible to make contact with the layers while maintaining the two-layer state.
Also, at the end of the development process, both
Since the developer is separated, it is possible to prevent the developer layer from being disturbed.
And the toner adheres to the non-image area on the image support.
The image can be prevented from being disturbed, and the toner
A thin layer of highly viscous liquid developer dispersed in high concentration is used.
The image is high resolution and easy to miniaturize.

According to the invention of claim 6, by virtue of the above-mentioned constitution, in addition to the effect of the invention of claim 3, there is provided a liquid developing device for an electrostatic latent image having good wettability of the liquid developer. Can be provided.

According to the invention described in claim 7, by virtue of the above-mentioned constitution, in addition to the effect of the invention described in claim 3, there is little pollution and the electrostatic latent image capable of improving the working environment is provided. It is possible to provide the liquid developing device.

A liquid developing device for an electrostatic latent image according to claim 8.
For the pre-wetting liquid, use the dielectric liquid with the above characteristics.
By doing so, there is no problem in developing, transferring, and fixing the liquid.
An electrostatic latent image formed on the photoconductor after drying
Easily evaporates during fixing without disturbing the fogging and toner
Do not let the lumps of the toner adhere to the photoconductor to improve the releasability.
To prevent image stains and fogging, and to improve image resolution and fogging.
To improve

[0075] The liquid developing device for an electrostatic latent image according to claim 9.
Is a dielectric liquid whose main component is silicone oil.
Due to this, a dielectric liquid having the characteristics of claim 8.
You can get the body.

According to the tenth aspect of the invention, by virtue of the above-mentioned constitution, in addition to the effect of the fourth aspect of the invention, the electrostatic latent image liquid developing device in which the toner is easily peeled off at the time of transfer Can be provided.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a liquid developing device for an electrostatic latent image that is an embodiment of the present invention.

FIG. 2 is a schematic front view of a developing device used in the electrostatic latent image liquid developing device shown in FIG.

FIG. 3 is a right side view of the developing device shown in FIG.

FIG. 4 is a diagram for explaining the operation of the electrostatic latent image liquid developing device shown in FIG. 1.

FIG. 5 is a diagram for explaining the entire developing process.

FIG. 6 is a diagram for explaining a state of an approaching process.

FIG. 7 is a diagram illustrating a state of a toner movement process.

FIG. 8 is a diagram for explaining a separation process of a non-image portion.

FIG. 9 is a diagram for explaining a process of separating an image portion.

FIG. 10 is a diagram for explaining the significance of thinning the liquid developer.

FIG. 11 is a diagram showing a state in which a developing roller and a photoconductor are in hard contact.

FIG. 12 is a diagram for explaining soft contacts of the electrostatic latent image liquid developing apparatus according to the present embodiment.

[Explanation of symbols]

10 Photoreceptor 20 Pre-wet device 30 Charging device 40 Exposure device 50 Developing device 51 Developing part 52 Coating part 52a, 52b, 52c, 52d Coating part 60 Transfer device 70 Cleaning device 510 Developing belt 512a, 512b, 612a, 612b, 612c
Drive rollers 514, 616 Scraping blades 520a, 520b, 520c, 520d Bellows pumps 522a, 522b, 522c, 522d Conveying roller 524 Arm 528 Guide blade 614 Secondary transfer roller 618 Heater

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yasushi Hasegawa 2-6-3 Otemachi, Chiyoda-ku, Tokyo Within Nippon Steel Corporation (72) Inventor Tsutomu Sasaki 2-6-Otemachi, Chiyoda-ku, Tokyo No. 3 within Nippon Steel Corporation (56) Reference JP 54-73036 (JP, A) JP 53-57039 (JP, A) JP 51-6733 (JP, A) JP 51-130232 (JP, A) JP-A-6-222678 (JP, A) JP-A-4-156486 (JP, A) JP-A-4-43070 (JP, A) JP-A-3-43749 (JP, A) Actual development Sho 54-174341 (JP, U) Japanese Patent Sho 51-17049 (JP, B2) Special Table 4-507464 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) ) G03G 13/10 G03G 15/10

Claims (10)

(57) [Claims] 1. An electrostatic latent image formed on an image support,
A liquid developing method for an electrostatic latent image, which is developed with toner that is charged developing particles, comprising a developer support carrying a liquid developer in which toner is dispersed in an insulating liquid, and at least two rollers. On the developer support through
Coating means for coating the liquid developer on the surface of the liquid developer, and the coating means rolls as the coating means approaches the developer support.
The width of the roller becomes smaller, and the liquid developer is insulated.
100 to 100 in which toner is dispersed in a high concentration in an ionic liquid
Characterized by high viscosity of 00 mPa · s
Liquid developing device for electrostatic latent image. 2. The liquid developing device for an electrostatic latent image according to claim 1, wherein a width of a roller of the rollers that is in contact with the developer support is smaller than a width of the developer support. 3. The developing unit of the roller is the developing unit.
Characterized in that the roller contacting the agent support is at the bottom
The liquid developing device for an electrostatic latent image according to claim 1 or 2. 4. The developer support of the roller is most suitable for the developer support.
Guide blade that moves the liquid developer to the center of the roller that is farthest away
4. Arrangement according to any one of claims 1, 2 and 3, characterized in that
4. A liquid developing device for an electrostatic latent image as described in 1. 5. The liquid developing device for the electrostatic latent image comprises:
Dielectric liquid with releasability and chemically inert on image support
A pre-wetting means for applying a pre-wetting liquid that is
Developer disposed with a minute gap from the image support.
High concentration of toner dispersed in insulating liquid on support
Apply high-viscosity liquid developer and apply to the developer support
Formed on the liquid support layer and the image support
Image by contacting with a pre-wet liquid layer
Presently, the high-viscosity liquid developer is supplied to the latent image surface of the support.
With image means Claims 1, 2, 3, characterized in that
4. The electrostatic latent image liquid developing device according to any one of 4 above. 6. The liquid developer has an insulating liquid having a viscosity of 0.5 to 1000 mPa · s and an electric resistance of 10 ¹² Ω.
cm or more, the surface tension is 21 dyne / cm or less, and the boiling point is 100 ° C. or more .
The liquid developing device for an electrostatic latent image according to any one of 3, 4, and 5 . 7. The liquid developing device for an electrostatic latent image according to claim 6, wherein the liquid developer uses silicon oil as an insulating liquid. 8. The liquid developer is a viscosity of the dielectric liquid.
Is 0.5 to 5 mPa · s, and electric resistance is 10 ¹² Ωcm or less
Above, boiling point is 100 ~ 250 ℃, surface tension is 21 dyne
/ Cm or less, claim 5,6,7
A liquid developing device for an electrostatic latent image according to any one of claims. 9. The liquid developer contains silicon as a main component.
Oil is used as the dielectric liquid.
The liquid developing device for an electrostatic latent image according to claim 8. 10. The liquid developer has an average particle size of 0.1.
5. A toner containing 5 to 40 .mu.m at a concentration of 5 to 40% .
8. A liquid developing device for an electrostatic latent image according to any one of 8 and 9.