JP2009300875A - Wet image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wet image forming apparatus capable of producing a liquid developer excellent in storage property, fixing property, developing property and transfer property in a developing device. <P>SOLUTION: The developing device 200 includes: a diluent liquid cartridge 70 storing a diluent liquid 72 comprising a carrier liquid only, which is dispersion medium; and a concentrated liquid developer cartridge 80 storing a concentrated liquid developer 82 comprising toner particles and the carrier liquid as the dispersion medium and having a higher concentration of the toner than that of a liquid developer 62. By increasing the viscosity of the dispersion medium in the concentrated liquid developer 82 in the concentrated liquid developer cartridge 80, a sedimentation rate of the toner particles is decreased to ensure storage stability. By reducing the viscosity of the dispersion medium of the diluent liquid 72 replenished from the diluent liquid cartridge 70 than the viscosity of the dispersion medium of the liquid developer 62, the viscosity of the dispersion medium in the liquid developer to be used for development is reduced since both of the dispersion media are mixed, and thereby improving fixing property and the like. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus, and more particularly to a wet image forming apparatus that forms an image using a liquid developer in which toner particles are dispersed in a carrier liquid.

  In an electrophotographic image forming apparatus, an electrostatic latent image formed on a photoreceptor is developed with toner particles, and the toner image is transferred to a recording sheet to form an image. In the case where an intermediate transfer member is provided, the toner image is temporarily transferred from the photosensitive member to the intermediate transfer member, and then transferred from the intermediate transfer member to the recording paper to form an image. Become. In the transfer process of such an image forming apparatus, an electrostatic transfer method is generally employed.

  For example, when a toner image on a photosensitive member is primarily transferred to an intermediate transfer member that is a transfer target, a voltage is applied to the intermediate transfer member disposed so as to face the photosensitive member, and the photosensitive member, the intermediate transfer member, An electric field is formed between the toner image and the toner image is electrostatically attracted to the intermediate transfer member by this electric field.

  In addition, when transferring the toner image of the intermediate transfer body to a sheet as a transfer target body, a voltage is applied from the back surface of the sheet disposed so as to face the intermediate transfer body by a transfer roller or the like, and the intermediate transfer body and the sheet An electric field is formed between the toner image and the toner image electrostatically attracted to the paper by this electric field.

  As a developer used for developing an electrostatic latent image formed on a photoreceptor, dry toner using toner particles composed of a material containing a colorant such as a pigment and a binder resin in a dry state; and toner There is a liquid developer in which particles are dispersed in an electrically insulating carrier liquid or the like.

  Since the liquid developer uses an insulating liquid as a medium, finer toner particles can be used as compared with dry toner. As a result, the liquid developer has better fine line image reproducibility, better gradation reproducibility, better color reproducibility, and better image formation at high speed than dry toner. It has the feature of being.

In this regard, various methods for generating a liquid developer have been proposed.
For example, Japanese Patent Application Laid-Open No. 2005-84419 describes a method for generating a carrier liquid in which a non-volatile solvent and a volatile solvent are mixed for the purpose of ensuring the fixability and safety of the liquid developer. ing.

  In Japanese Patent Application Laid-Open No. 2007-41027, in order to generate a liquid developer in which toner particles are stably dispersed, toner particles are composed of two types of liquids having different viscosities as carrier liquids. In which a liquid developer is produced by pulverizing and mixing with a liquid having a high viscosity.

Japanese Patent Application Laid-Open No. 9-160389 describes a method of adjusting the viscosity of the liquid developer in order to maintain the image quality at the start of development and after the start of development.
JP 2005-84419 A JP 2007-41027 A JP-A-9-160389

  On the other hand, as described above, the liquid developer comprises toner particles and a carrier liquid that is a dispersion medium for dispersing the toner particles. If the carrier liquid that is the dispersion medium has a low viscosity, the fixability is good. Sedimentation is accelerated, toner particles are aggregated, and storage stability is deteriorated.

  On the contrary, when the viscosity of the carrier liquid which is a dispersion medium is increased, the sedimentation rate of the toner particles is decreased and the storage property is improved, but the fixing property is deteriorated. In addition, when the viscosity of the carrier liquid, which is a dispersion medium, is high, the moving speed of the toner when an electric field is applied is slowed, and developability and transferability are also deteriorated.

  Accordingly, in the liquid developer, storage property, fixing property, developability, and transfer property are in a trade-off relationship.

  In general, in a wet image forming apparatus, a concentrated liquid developer for replenishing toner particles and a diluting liquid for replenishing a carrier liquid as a dispersion medium are used to generate a liquid developer used in the apparatus. And are provided.

  At this point, the concentrated liquid developer or diluent is stored in the cartridge and can be detached from the apparatus main body. When the concentrated liquid developer or diluent in the apparatus runs out, the cartridge is replaced with a new cartridge.

  The concentrated liquid developer is generally stored in a cartridge outside the apparatus, and a stirring mechanism or the like for stirring toner particles is usually not provided. Therefore, in the concentrated liquid developer, it is necessary to improve the storage property in the cartridge for replenishment, but it is also necessary to consider the storage property, the fixing property, the developing property, and the transfer property. In any case, this point is not described.

  The present invention has been made to solve the above-described problems, and in a developing device, a liquid developer excellent in storage property, fixing property, developability, and transferability can be generated. An object is to provide a wet image forming apparatus.

  The wet image forming apparatus according to the present invention forms a toner image on an image carrier using a liquid developer in which toner is dispersed in a carrier liquid and transfers the toner image on the image carrier to a transfer target. An image forming apparatus, a developing tank storing a liquid developer used for development, a concentrated liquid developer in which concentrated toner is dispersed in a carrier liquid, and a dilution of only a carrier liquid for diluting the concentrated liquid developer And an adjusting unit for mixing the liquid and supplying the liquid developer to the developing tank. The viscosity of the carrier liquid of the concentrated liquid developer is higher than the viscosity of the carrier liquid of the diluted liquid.

  Preferably, the viscosity of the carrier liquid of the diluent is lower than the viscosity of the carrier liquid of the liquid developer used for development.

  Preferably, the adjustment unit mixes the concentrated liquid developer and a first diluent having a viscosity lower than that of the carrier liquid of the concentrated liquid developer to generate an intermediate concentrated liquid developer; A second mixing unit that generates a liquid developer used for development by mixing the carrier liquid of the intermediate concentrated liquid developer generated in one mixing unit with the second diluent having only the carrier liquid having the same viscosity. .

  In the wet image forming apparatus according to the present invention, the adjustment unit mixes the concentrated liquid developer having a high carrier liquid viscosity with the diluent having a low carrier liquid viscosity to generate a liquid developer. Therefore, by using a concentrated liquid developer having a high viscosity of the carrier liquid, the settling speed of the toner particles is slowed, storage stability is ensured, and the viscosity of the carrier liquid of the generated liquid developer is reduced, Fixability, developability and transferability can be ensured.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are also the same.

(Embodiment 1)
FIG. 1 is a schematic configuration diagram illustrating an example of a wet image forming apparatus according to the first embodiment of the present invention.

  Referring to FIG. 1, the wet type image forming apparatus according to the first embodiment of the present invention is provided with a photoconductor 20 that is a drum-shaped image carrier, and the periphery of photoconductor 20 has a rotational direction indicated by an arrow. A developing device 200, a pressure roller 10, a cleaning blade 22, an eraser lamp 24, a charging device 26, and an exposure device 28 are arranged in order.

  The surface of the photoreceptor 20 is uniformly charged to a predetermined surface potential by the charging device 26. Thereafter, image information is exposed by the exposure device 28 to form an electrostatic latent image on the surface of the photoreceptor 20. Next, the electrostatic latent image on the photoconductor 20 is developed with a liquid developer containing toner particles and a carrier liquid by the developing device 200, and a toner image is formed on the surface of the photoconductor 20. At this time, not only toner particles but also a carrier liquid as a dispersion medium adheres to the surface of the photoconductor 20.

  Then, the toner image formed on the surface of the photoconductor 20 is conveyed to a transfer portion that is a portion facing the pressure roller 10. In the transfer portion, the transfer target 100 is conveyed in the direction of the arrow, and the toner particles on the photosensitive member 20 are transferred to the transfer target 100 by the force of the voltage having the opposite polarity to the toner particles applied to the pressure roller 10. Is done. The transferred object 100 onto which the toner particles are transferred is conveyed to a fixing unit (not shown) and the toner image is fixed.

  On the other hand, a cleaning blade 22 is provided on the photoconductor 20 after passing through the transfer portion, and collects transfer residual toner particles and a dispersion medium remaining on the photoconductor 20. The photoreceptor 20 from which the toner particles and the dispersion medium have been recovered is exposed by the eraser lamp 24, and the latent image potential is cancelled. By repeating these steps, images are printed one after another.

  Here, the liquid developer includes, as main components, an insulating liquid that is a carrier liquid, toner particles that develop an electrostatic latent image, and a dispersant that disperses the toner particles.

  The carrier liquid can be used without particular limitation as long as it is generally used for an electrophotographic liquid developer. Among these, a non-volatile liquid is preferable. Examples of the non-volatile liquid include silicon oil, mineral oil, paraffin oil, and mineral oil.

  The toner particles can be used without any particular limitation as long as they are generally used for electrophotographic liquid developers. As the toner binder resin, for example, a thermoplastic resin such as polystyrene resin, styrene acrylic resin, acrylic resin, polyester resin, epoxy resin, polyamide resin, polyimide resin, or polyurethane resin can be used. It is also possible to use a mixture of a plurality of these resins. Also, commercially available pigments and dyes used for coloring the toner can be used. For example, carbon black, bengara, titanium oxide, silica, phthalocyanine blue, phthalocyanine green, sky blue, benzidine yellow, lake red D, etc. can be used as the pigment. Solvent red 27, acid blue 9, or the like can be used as the dye.

  As a method for preparing the liquid developer, it can be prepared based on a commonly used technique. For example, the binder resin and the pigment are melt-kneaded using a pressure kneader, a roller mill or the like at a predetermined blending ratio and uniformly dispersed, and the obtained dispersion is finely pulverized by, for example, a jet mill. By classifying the obtained fine powder with, for example, an air classifier, a colored toner having a desired particle diameter can be obtained. The obtained toner particles are mixed with an insulating liquid as a carrier liquid at a predetermined blending ratio. This mixture can be uniformly dispersed by a dispersing means such as a ball mill to obtain a liquid developer.

Next, the configuration of the developing device 200 will be described.
The developing device 200 is provided with a developing roller 30, and a part of the developing roller 30 is immersed in the liquid developer 42 in the storage tank 40.

  Stored in the storage tank 40 is a liquid developer 42 composed of toner particles composed of a colorant and a resin and a carrier liquid in which the particles are dispersed. In addition, since the carrier liquid that is a dispersion medium has poor fixability when the viscosity exceeds 10 mPa · s, the viscosity of the carrier liquid that is the dispersion medium of the liquid developer 42 in the storage tank 40 is 10 mPa · s or less. Is desirable.

  As the developing roller 30 rotates, the liquid developer 42 is pumped up. The developing roller 30 is provided with a regulating blade 35 for regulating the liquid developer 42 to a constant thickness, and the thickness of the pumped liquid developer 42 is constant. Further, the toner particles of the liquid developer 42 are charged by a charging device 32 such as a corona charger.

FIG. 2 is a diagram for explaining the state of the liquid developer before development, the development portion, and after separation.
Referring to FIG. 2, before development, the liquid developer 42 that is regulated to a constant thickness as shown in FIG. 2A is used as a toner between the photosensitive member 20 after the toner particles are charged. It is carried to the developing unit for forming an image and brought into contact with the photoreceptor 20.

  An electrostatic latent image having the same polarity as the toner particles is formed on the surface of the photosensitive member 20 conveyed to the developing unit, and the potential of the image portion is low and the potential of the non-image portion is high.

A potential between the image portion potential and the non-image portion potential is applied to the developing roller 30.
In the developing portion, as shown in FIG. 2B, the toner particles in the image portion move to the surface of the photoreceptor 20 and the toner particles in the non-image portion move to the surface of the developing roller 30 due to the potential difference.

  Thereafter, as shown in FIG. 2C, the photosensitive member 20 and the developing roller 30 are separated, so that the liquid developer 42 is divided into the photosensitive member 20 and the developing roller 30, respectively.

  The toner particles and the dispersion medium adhere to the image portion on the photoconductor 20 and only the dispersion medium adheres to the non-image portion and is consumed.

  On the other hand, only the dispersion medium exists at a location corresponding to the image portion of the photoconductor 20 on the developing roller 30, and toner particles and the dispersion medium exist at a location corresponding to the non-image portion.

  A cleaning blade 34 is provided on the developing roller 30 after the development, and the toner particles and the dispersion medium after the development are cleaned and collected in the collection tank 50.

  The recovery liquid containing the toner particles and the dispersion medium recovered in the recovery tank 50 is supplied to the adjustment tank 60 via the pump 91.

  Since the toner concentration of the liquid developer that has passed through the developing unit is different from the original concentration, the adjustment tank 60 is provided with means (not shown) for detecting the toner concentration.

  As a means for detecting the toner density, an optical means may be used, or a means for obtaining from the torque when the liquid developer 62 is stirred may be used.

  The adjustment tank 60 is provided with means for detecting the amount of the liquid developer 62 and means for stirring the liquid developer 62.

  The liquid developer 62 adjusted in the adjustment tank 60 is supplied to the storage tank 40 via the pump 93.

  Further, the developing device 200 includes a diluent cartridge 70 that stores the diluent 72 only from a carrier liquid that is a dispersion medium, and a concentrated liquid that includes toner particles and a carrier liquid that is a dispersion medium, and has a higher toner concentration than the liquid developer 62. A concentrated liquid developer cartridge 80 for storing the developer 82 is provided.

  These cartridges can be removed from the apparatus main body, and are provided so that the cartridges can be replaced when the diluent 72 and the concentrated liquid developer 82 are used up. These cartridges become respective storage containers until they are set in the apparatus.

  It is conceivable that the concentrated liquid developer 82 is stored for a long period of time before being set in the apparatus. At this time, the toner particles may settle and the toner particles may aggregate. In order to prevent toner particles from aggregating, it is effective to increase the viscosity of the carrier liquid as a dispersion medium, and specifically, it is preferably 15 mPa · s or more. That is, the viscosity of the carrier liquid that is the dispersion medium of the concentrated liquid developer 82 is preferably 15 mPa · s or more.

  By increasing the viscosity of the dispersion medium of the concentrated liquid developer 82 in the concentrated liquid developer cartridge 80, the sedimentation rate of the toner particles is decreased, and storage stability can be ensured.

  When the liquid developer 42 is consumed by printing, the toner concentration of the liquid developer 62 and the amount of the liquid developer are detected in the adjustment tank 60, and the concentrated liquid developer 82 supplied from the concentrated liquid developer cartridge 80 The diluent 72 supplied from the diluent cartridge 70 is replenished.

  In the case of the wet development method, since the toner particles and the dispersion medium are consumed in the image portion and the dispersion medium is consumed in the non-image portion as described above, the consumption amount of the dispersion medium is large.

Specifically, when an image in which the toner concentration of the liquid developer 42 is 25 wt (weight)% and the ratio of the image portion (printing portion) to the entire image area is 20% is printed, the toner particles per m ² are 0.00. 3 g and 1.8 g of the dispersion medium are consumed. As a result, the toner concentration of the liquid developer 42 collected from the developing roller 30 increases to 31 wt%.

  In order to compensate for the consumed amount, 0.8 g of concentrated liquid developer 82 (toner particles 0.3 g, dispersion medium 0.5 g) from the concentrated liquid developer cartridge 80 having a toner concentration of 40 wt% and the diluted liquid from the diluent cartridge 70 are used. Of 1.3g.

As a result, it is possible to replenish the consumed toner particles and the dispersion medium.
Next, each dispersion medium is considered.

  The dispersion medium includes a dispersion medium for the liquid developer 62, a dispersion medium for the concentrated liquid developer 82, and a dispersion medium for the diluent 72.

  As described above, the dispersion medium of the liquid developer 42 used for development is preferably 10 mPa · s or less from the viewpoint of fixability, and the dispersion medium of the concentrated liquid developer 82 is preferably 15 mPa · s or more from the viewpoint of storage. In consideration of storability, when a high-viscosity dispersion medium for the concentrated liquid developer 82 is used and the liquid developer 62 in the adjustment tank 60 is replenished, the viscosity of the dispersion medium in the liquid developer 62 increases and fixing. May be worse.

  Therefore, in the system according to the first embodiment of the present invention, the viscosity of the dispersion medium of the diluent 72 supplied from the diluent cartridge 70 is set lower than the viscosity of the dispersion medium of the liquid developer 62.

  As described above, in the wet development method, only the concentrated liquid developer 82 is rarely replenished, and the diluent 72 is also replenished. Therefore, even if a highly viscous dispersion medium is used for the concentrated liquid developer 82, the diluent 72 is used. If a low-viscosity dispersion medium is used, it is possible to mix the dispersion mediums and reduce the viscosity.

  FIG. 3 is a diagram illustrating a change in viscosity when a high-viscosity dispersion medium and a low-viscosity dispersion medium are mixed.

  In FIG. 3, Moresco White P70 (manufactured by Matsumura Oil Research Co., Ltd., viscosity 15 mPa · s) as a dispersion medium of the concentrated liquid developer 82 and IPS2028 (manufactured by Idemitsu Kosan Co., Ltd.) as a dispersion medium of the diluent 72 Viscosity change when mixing with a viscosity of 2.3 mPa · s.

  As a specific example, IPS2028 (manufactured by Idemitsu Kosan Co., Ltd., viscosity 2.3 mPa · s) as a dispersion medium for the diluent 72, and Moresco White P40 (manufactured by Matsumura Oil Research Co., Ltd.) as a dispersion medium for the liquid developer 62, Viscosity: 4.5 mPa · s), using Moresco White P70 (manufactured by Matsumura Oil Research Co., Ltd., viscosity: 15 mPa · s) as a dispersion medium for the concentrated liquid developer 82, An image with a ratio of 20% was printed 1000 sheets while supplying the concentrated liquid developer 82 and the diluent 72.

At that time, the viscosity of the dispersion medium of the liquid developer 42 was 5 mPa · s.
Further, although the liquid developer 62 using Moresco White P40 as a dispersion medium is used, a liquid developer obtained by diluting the concentrated liquid developer 82 with the diluent 72 can also be used.

  The viscosity of the dispersion medium according to the embodiment of the present invention was measured in an environment at room temperature of 25 degrees using VISCOMATE (MODEL VM-10A) manufactured by CBC Materials.

  The dispersion medium of the liquid developer 42 after printing 1,000 sheets was centrifuged at 15000 rpm for 10 minutes with a centrifugal separator H-9R (manufactured by KOKUSAN) to separate only the dispersion medium, and then the viscosity was measured.

  Therefore, even when the liquid developer is repeatedly used, the viscosity of the dispersion medium of the liquid developer does not increase greatly, and by using a dispersion medium having a high viscosity as the dispersion medium of the concentrated liquid developer 82, Fixability can be improved by reducing the viscosity of the dispersion medium of the liquid developer used for development while improving storage.

  Further, by lowering the viscosity of the dispersant of the liquid developer 42 in the storage tank 40 (for example, 10 mPa · s or less), the moving speed of the toner particles with respect to the electric field can be increased, and the developability and transferability can be improved. is there. In addition, handling of the liquid developer in the apparatus such as liquid feeding by a pump or the like is facilitated.

  In addition, the carrier liquid that is a dispersant during heating is frequently evaporated and penetrated into the paper that is a transfer target, so that the fixability can be improved.

(Embodiment 2)
FIG. 4 is a diagram illustrating a configuration of developing device 210 according to the second embodiment of the present invention.

  Referring to FIG. 4, developing device 210 according to the second embodiment of the present invention replaces concentrated liquid developer cartridge 80 with concentrated liquid developer tank 80 #, as compared with developing device 200, and dilution liquid 97. The difference is that a diluent cartridge 95 for replenishing the liquid and a concentrated liquid developer cartridge 90 for replenishing the concentrated liquid developer 92 are further provided. Since the other points are the same, detailed description thereof will not be repeated.

  When the concentrated liquid developer 82 stored in the concentrated liquid developer tank 80 # runs out, the concentrated liquid developer cartridge 90 is replaced and the concentrated liquid developer 92 is replenished.

  Therefore, the concentrated liquid developer 92 in the concentrated liquid developer cartridge 90 is stored outside the apparatus, and it is necessary to increase the viscosity of the dispersion medium of the concentrated liquid developer 92 in order to ensure storability.

  In this example, as an example, the viscosity of the dispersion medium of the liquid developer 62, the dispersion medium of the diluent 72 of the diluent cartridge 70, and the dispersion medium of the concentrated liquid developer 82 of the concentrated liquid developer tank 80 # are all the same. .

  For the above reasons, the dispersion medium of the concentrated liquid developer 92 of the concentrated liquid developer cartridge 90 is set higher than the viscosity of the dispersion medium of the liquid developer 62, the dispersion medium of the diluent 72, and the dispersion medium of the concentrated liquid developer 82.

  The viscosity of the dispersion medium of the diluent 97 of the diluent cartridge 95 is set lower than the viscosity of the dispersion medium of the liquid developer 62, the dispersion medium of the diluent 72, and the dispersion medium of the concentrated liquid developer 82.

  When the concentrated liquid developer 82 runs out, the concentrated liquid developer 92 is added from the concentrated liquid developer cartridge 90 to the concentrated liquid developer tank 80 #. At this time, the diluent 97 from the diluent cartridge 95 is also added to the concentrated liquid developer tank 80 #, and the viscosity of the concentrated liquid developer 82 is lowered to a predetermined value.

The predetermined value is set to the same value as the viscosity of the dispersion medium of the diluent 72.
In this way, the viscosity of the dispersion medium of the liquid developer 62, the dispersion medium of the diluent 72, and the dispersion medium of the concentrated liquid developer 82 can be made the same, and the concentrated liquid developer 82 and the diluent 72 can be made the same. Even if the liquid is replenished, the viscosity of the dispersion medium of the liquid developer 62 is stable without change, and the storage stability of the concentrated liquid developer 92 in the concentrated liquid developer cartridge 90 can be satisfied while satisfying the fixing property. It becomes.

  As a specific example, IPS2028 (manufactured by Idemitsu Kosan Co., Ltd., viscosity 2.3 mPa · s) and Moresco White P70 (( (Made by Matsumura Oil Research Co., Ltd., viscosity 15 mPa · s) mixed at 1: 4.

  The concentrated liquid developer 92 in the concentrated liquid developer cartridge 90 has a toner concentration of 45 wt%, and its dispersion medium is Moresco White P70 (viscosity 15 mPa · s).

  IPS 2028 (made by Idemitsu Kosan Co., Ltd., viscosity 2.3 mPa · s) and Moresco White P70 (made by Matsumura Oil Research Co., Ltd., viscosity 15 mPa · s) so that the diluent 72 also has a viscosity of 8 mPa · s. What was mixed 1: 4 is used.

  Diluent 97 uses IPS2028 (Idemitsu Kosan Co., Ltd., viscosity 2.3 mPa · s).

  The diluent 97 is added to the concentrated liquid developer 92 and diluted so that the toner concentration of the concentrated liquid developer 82 is 40 wt%. By doing so, the viscosity of the dispersion medium of the concentrated liquid developer 82 becomes 8 mPa · s.

  The viscosity of the dispersion medium of the concentrated liquid developer 92 is determined by the toner concentration of the concentrated liquid developer 92 in the concentrated liquid developer cartridge 90, the toner concentration of the concentrated liquid developer tank 80 #, and the viscosity of the dispersion medium of the diluent 97. I can do it. At that time, other than the above can be applied as long as the viscosity of the dispersion medium is 15 mPa · s or more.

  As in the system according to the second embodiment of the present invention, the concentrated liquid developer 92 in the concentrated liquid developer cartridge 90 to be replenished is more dispersed than the concentrated liquid developer 82 replenished to the liquid developer 62 in the apparatus. By increasing the viscosity, it is possible to improve storage properties.

  Further, the concentrated liquid developer 92 in the concentrated liquid developer cartridge 90 to be replenished is diluted with a low-viscosity diluent 97 in the apparatus to generate a concentrated liquid developer 82, and the concentrated liquid developer 82 in the apparatus is also produced. By making the dispersion medium viscosity equal to the dispersion medium viscosity of the liquid developer 62 and the diluent 72, the viscosity of the dispersion medium of the liquid developer 62 does not change when the concentrated liquid developer 82 is replenished. It is possible to make it.

  In the second embodiment, the dispersion medium of the diluent 72 has the same viscosity as the dispersion medium of the liquid developer 62. However, the dispersion medium of the diluent 72 is dispersed in the liquid developer 62. It is also possible to use one having a lower viscosity than the medium. For example, the same one as the diluent 97 may be used.

  Although the viscosity of the dispersion medium of the liquid developer 62 is lowered by replenishing the diluent 72, there is no problem even if the viscosity of the dispersion medium of the liquid developer 62 is lowered.

  In the above-described embodiment, the example of direct transfer from the photoconductor 20 to the paper to be transferred has been described. However, it is naturally possible to apply the transfer to a configuration using an intermediate transfer body.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a schematic configuration diagram illustrating an example of a wet image forming apparatus according to an embodiment of the present invention. It is a figure explaining the state of the liquid developer before image development, after a development part, and after separation. It is a figure explaining the change of a viscosity when a high-viscosity dispersion medium and a low-viscosity dispersion medium are mixed. It is a figure explaining the structure of the image development apparatus 210 according to Embodiment 2 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Pressure roller, 20 Photoconductor, 22 Cleaning blade, 24 Eraser lamp, 26, 32 Charging device, 28 Exposure device, 30 Developing roller, 34 Cleaning blade, 35 Control blade, 40 Storage tank, 50 Collection tank, 60 Adjustment tank 70,95 Diluent cartridge, 80,90 Concentrated liquid developer cartridge, 91,93 Pump.

Claims (3)

A wet image forming apparatus that forms a toner image on an image carrier using a liquid developer in which toner is dispersed in a carrier liquid, and transfers the toner image on the image carrier to a transfer target,
A developing tank in which the liquid developer used for development is stored;
Mixing a concentrated liquid developer in which concentrated toner is dispersed in a carrier liquid and a diluent of only a carrier liquid for diluting the concentrated liquid developer, and supplying the liquid developer to the developer tank An adjustment unit,
The wet-type image forming apparatus, wherein the carrier liquid of the concentrated liquid developer has a viscosity higher than that of the carrier liquid of the diluent.   The wet image forming apparatus according to claim 1, wherein a viscosity of the carrier liquid of the dilution liquid is lower than a viscosity of a carrier liquid of a liquid developer used for the development. The adjustment unit is
A first mixing unit that mixes the concentrated liquid developer with a first diluent having a lower viscosity than a carrier liquid of the concentrated liquid developer to generate an intermediate concentrated liquid developer;
A second mixture for producing the liquid developer used for the development by mixing the carrier liquid of the intermediate concentrated liquid developer generated in the first mixing unit and the second diluent having only the carrier liquid having the same viscosity. The wet image forming apparatus according to claim 1, further comprising:

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