WO1995015515A1 - Image forming apparatus and image forming method - Google Patents

Abstract

The invention relates to a liquid developing method of an electrostatic image and a liquid developing apparatus, said liquid developing method being an image forming method of developing an electrostatic latent image produced on a photosensitive member (10) by means of toner to transfer the same to a recording medium, said method comprising a prewetting process of applying a prewetting liquid to the photosensitive member (10), a developing process of supplying a liquid developer of high concentration and high viscosity to a latent image surface of the photosensitive member (10), a primary transfer process of transferring a toner image formed on the photosensitive member (10) to an intermediate transfer belt (602), a secondary transfer process of transferring a toner image, which has been transferred to the intermediate transfer belt (602), to a recording medium conveyed onto a second transfer roller (603), and a fixing process of fixing the transferred toner image on the recording medium.

Description

 Description Image Forming Apparatus and Method Applicant filed with the Japan Patent Office as the receiving Office under the name of `` Liquid Developing Method and Liquid Developing Apparatus '' assigned to the assignee of the present application, September 30, 1994 PCT application filed on January 1, PCT / JP94 / 01541, and a PCT application filed on February 1, 1994 under the name of `` liquid developing device for electrostatic latent images '' Related to PC TZ JP94Z, the contents of which are incorporated by reference as part of this application.

 Technical field

 The present invention relates to an image forming method and an image forming method, in which an electrostatic latent image formed by a method such as electrophotography, electrostatic recording, or ionography is visualized using a liquid developer and then transferred to a recording medium. It relates to a forming apparatus.

 Background art

Conventionally, an electrostatic latent image formed on an image support is developed with charged toner, which is a visualized particle, and the toner image formed on the image support is recorded on a recording medium. There is a method of forming a monochrome or color image by transferring the image to an image. In such an image forming method, when a toner image formed on a latent image surface of an image support is transferred to a recording medium such as paper, the transfer image is charged with a charge having a polarity opposite to that of the toner. The body is brought into contact with the image support via paper, and transfer is performed using electrostatic force. In addition, in an image forming apparatus using a liquid developer, the paper is wetted with a pre-wet liquid to facilitate transfer of the toner to the paper and improve transferability. A method of treating the surface of paper is used.

 At this time, when a liquid developer was used as a developer for visualizing the electrostatic latent image, when the pressing force of the intermediate transfer member against the image support was high, the image was transferred to the intermediate transfer member. There has been a problem that the toner image is disturbed, whereby the image transferred to the recording medium may flow. Also, a large amount of the pre-wet solution must be supplied because the paper absorbs the pre-wet solution. There was a problem that the image was not clear.

 Furthermore, in the above-described liquid developing method, since the amount of the pre-treatment liquid for treating the surface of the paper varies depending on the type of paper, only a specific type of paper is used as a recording medium. There is a problem that it cannot be done. In addition, there is a problem that ozone is generated when the transfer body is charged with a charge having a polarity opposite to that of the toner by corona discharge.

High-concentration, high-viscosity liquid developer that increases adhesion to image supports and transfer media (100 to 100 Om Opas with toner dispersed at high concentration in insulating liquid) However, it is not clear how to transfer the toner image formed on the latent image surface of the image support onto a recording medium in a favorable manner. The present invention has been made based on the above circumstances, and prevents a toner image from being disturbed when a toner image formed on an image support comes into contact with an intermediate transfer member. Secondary transfer without wetting with a pre-wet solution allows the toner image formed on the image support to be transferred irrespective of the type of recording medium It is an object of the present invention to provide an image forming method and an image forming apparatus using a liquid developer having a high concentration and high viscosity.

 Disclosure of the invention

 The electrostatic latent image formed on the image support of the present invention is developed with toner, which is charged visualized particles, and the toner image formed on the image support is transferred to a recording medium. The method uses a high-viscosity liquid developer of 100 to 100 OmPas in which the toner is dispersed in a high concentration in a green-colored liquid. A toner image formed on the latent image surface of the image support, a primary transfer process of transferring the toner image formed on the latent image surface of the image support onto the intermediate transfer member, and a secondary transfer member. And a secondary transfer step of transferring a toner image on the intermediate transfer member to the recording medium by interposing a recording medium between the intermediate transfer members.

 In the image forming method of the present invention, prior to the developing step, a pleat solution, which is a dielectric liquid having releasability and chemically inactive, is coated on the image support. It may include a pre-wet process.

At least one of the image support and the intermediate transfer member is acceptable The primary transfer step may be performed by using an intermediate transfer body having an adhesive layer formed on a surface in contact with the image support, by using an adhesive force. The toner image on the image support may be transferred onto an intermediate transfer member.

 Furthermore, primary transfer or secondary transfer may be performed by electrostatic force using a conductive medium.

 Further, the toner image primarily transferred onto the intermediate transfer member by heating the secondary transfer member may be secondarily transferred to a recording medium and fixed at the same time.

 Further, the electrostatic latent image formed on the image support is developed with toner, which is charged visualized particles, and the toner image formed on the image support is transferred to a recording medium. The image forming apparatus of the present invention

 A high viscosity liquid developer of 100 to 1000 mPas in which toner is dispersed in a high concentration in an insulating liquid is applied to the latent image surface of the image support by the developer support. Developing means for supplying a toner image on the image support to form a toner image on the image support;

 Primary transfer means for transferring the toner image formed on the image support onto the intermediate transfer body,

 Secondary transfer means for transferring the toner image transferred onto the intermediate transfer member to the recording medium by pressing the secondary transfer member against the intermediate transfer member via the recording medium;

At least one of the image support and the intermediate transfer member is formed of a flexible member. I do.

 The image forming apparatus according to the present invention further includes a pre-wet means for applying a pre-jet liquid, which is a dielectric liquid having releasability and chemically inactive, on the image support, May be provided.

 Further, by heating the secondary transfer member, the toner image primarily transferred on the intermediate transfer member may be fixed simultaneously with the secondary transfer to the recording medium.

 Further, the intermediate transfer member may have an adhesive layer on the surface in contact with the image support.

 The adhesive layer may be formed of fluorosilicone rubber.

 According to the image forming method of the present invention, a high-viscosity liquid developer containing a high concentration of toner is used, and an intermediate transfer body is used in the transfer process. Therefore, a high-resolution image can be formed using various papers. Obtainable.

 According to the method of applying a splitting liquid to the image support prior to the developing step, a latent image on the image support surface is visualized by a high-viscosity liquid developer containing a high concentration of toner. When a toner image is formed by forming a toner image, toner is not attached to portions other than the latent image surface, so that the toner image becomes clear. Furthermore, when the toner image on the image support is transferred to the intermediate transfer member, the toner image is separated from the image support, so that the toner image can be easily transferred to the intermediate transfer member and the toner is transferred to the image support. Hard to remain.

In addition, by using an intermediate transfer member, Since the formed toner image is not directly transferred to the recording medium, the intermediate transfer is performed with a constant amount of the preset liquid without taking into account the surface roughness of the recording paper and the water absorption of the preset liquid. Primary transfer onto the body is possible. Furthermore, the toner image primarily transferred to the intermediate transfer body is secondarily transferred to the recording medium without using electrostatic force by using the pressing force of the secondary transfer body to the intermediate transfer body. The method does not require the surface of the recording medium to be treated by wetting the recording medium with the splitting liquid, and therefore, does not affect the surface roughness of the recording medium of the recording medium or the water absorption of the splitting liquid. Good secondary transfer is possible. Further, since the liquid developer in which the toner is dispersed at a high concentration is used, the liquid amount can be much smaller than that of a conventional liquid developer having a low concentration. When the viscosity of the liquid developer exceeds 1000 mPas, it becomes difficult to agitate the insulating liquid and the toner, and the question is how to make the liquid developer. It becomes a title. Therefore, a liquid developer of 1000 OmPas or more is not cost-effective and is not practical. On the other hand, when the temperature is less than 100 mPas, the toner concentration becomes lower and the dispersibility of the toner becomes worse, so that it is not possible to develop the developer in a thin layer. .

 Further, since the toner image on the intermediate transfer body having a smooth surface is transferred to the recording medium by pressing, it is not necessary to infiltrate the recording medium with the pre-jet liquid in advance.

When the image support or the intermediate transfer member has flexibility, the toner image on the image support and the intermediate transfer member come into contact with each other. Since the contact pressure during the transfer can be dispersed, the toner transferred on the intermediate transfer member does not flow and the image becomes clear.

 In the case where an adhesive layer is formed on the surface of the intermediate transfer member and the toner image is transferred by the adhesive force, the transfer of the toner image from the intermediate transfer member to the recording medium is more easily performed. Also, ozone is not generated in the equipment because no electrostatic force is used.

 Furthermore, when the adhesive force changes with temperature, transfer control becomes easier. If the adhesive layer of the intermediate transfer member is made of fluorosilicone rubber, the toner is easily peeled off when heat is applied, so it is heated during the secondary transfer to remove the toner from the image support. The toner image can be clearly transferred to the recording medium.

 In addition, when the secondary transfer body is heated and the image is fixed at the same time as the transfer, a separate fixing device is not required, and the entire apparatus can be made compact. .

Incidentally, the insulating liquid of the liquid developer, the viscosity 0. 5 ~ 1 0 0 0 m P a · s, electric resistance 1 0 ^{1 2} Omega cm or more, a surface tension 2 1 ά yn / cm or less, the boiling point 1 0 0 When the temperature is not lower than ° C, a high-viscosity liquid developer having an extremely small content of an insulating liquid can be obtained. Since the liquid developer layer formed on the developer support is formed in a thin layer, the amount of insulating liquid contained in the liquid developer adhering to the latent image surface of the image support is extremely small. Therefore, the amount of insulating liquid absorbed by paper or the like at the time of transfer is extremely small, but since the viscosity is less than 100 mPas, the insulating liquid can be transferred to paper or the like. There is no particular problem of adhering. In addition, since the viscosity is 0.5 mPa · s or more, its volatility is not high enough to be regulated as a dangerous substance. Since the insulating liquid has a boiling point of 100 ° C. or higher, it hardly vaporizes, so there is no problem with the method of storing the developer, and it is not necessary to make the entire apparatus a sealed structure, and the working environment deteriorates. do not do. Since the electric resistance is at least 10 ¹² Ωcm, there is no problem of toner conductivity, and it can be used sufficiently as a developer. Since the surface tension is 21 dyn / cm or less, it has good wettability and good compatibility with the pre-wet solution.

Also, pre-c or falling edge of preparative liquid, viscosity 0. 5 ~ 5 m P a 's resistance 1 0 ¹² Ω cm or more, the boiling point 1 0 0 ~ 2 5 0 ° C, surface tension 2 1 dyn / cm or less In some cases, it is possible to obtain a splitting liquid having good releasability and good insulating properties.

Since the intermediate transfer member used in the present invention has a small absorption effect of the pre-plate solution, the amount of the pre-jet solution in the primary transfer can be small. However, when the toner image on the image support is primarily transferred to the intermediate transfer body, a small amount of the preset liquid adheres to the intermediate transfer body and is absorbed by the recording paper during the secondary transfer Therefore, it is necessary to evaporate during fixing. For this reason, the viscosity is desirably 0.5 to 5 mPa · s in order to easily evaporate. If the viscosity is 5 mPas or more, evaporation becomes difficult, and if the viscosity is 0.5 mPas or less, volatility increases and it is subject to legal regulations, which is preferable. Absent. If the boiling point is lower than 100 ° C, the amount of evaporation increases, so there is a problem with the pre-wet solution storage method, and the entire system It is necessary to use a closed structure, and it is difficult to improve the working environment. On the other hand, if the boiling point is more than 250 ° C, the paper curls during fixing and cannot be used, and the energy required for heating increases, which is not economical. If the electrical resistance is less than ^{10 12} Ωcm, the insulation is poor, and it cannot be used as a plug-in solution. The larger the electrical resistance, the better. If the surface tension is more than 21 dyn / cm, the wettability will be poor and the familiarity with liquid developers will be poor. The smaller the surface tension, the better.

 The image forming apparatus of the present invention is capable of obtaining a clear image using a liquid developer, but is compact and economical, and does not deteriorate the use environment.

 BRIEF DESCRIPTION OF THE FIGURES

 FIG. 1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment of the present invention.

 FIG. 2 is a schematic perspective view of a pre-weight device used in the image forming apparatus shown in FIG.

 FIG. 3 is a diagram for explaining the operation of the image forming apparatus shown in FIG.

 FIG. 4 is a diagram for explaining the operation of the preset device shown in FIG.

 FIG. 5 is a diagram showing the flow of the pre-outlet liquid when the pre-outlet liquid supply member is brought into contact with the photosensitive drum.

FIG. 6 is a diagram for explaining the entire development process. FIG. 7 is a diagram showing a state of the approach process. FIG. 8 is a diagram showing a state of the toner transfer process. FIG. 9 is a diagram illustrating a separation process of a non-image portion.

 FIG. 10 is a diagram showing the separation process of the image part.

 FIG. 11 is a diagram for explaining the significance of thinning the liquid developer.

 FIG. 12 is a diagram showing a state in which the developing roller and the photosensitive drum are hard-connected.

 FIG. 13 is a diagram for explaining a soft contact of the image forming apparatus according to the first embodiment.

 FIG. 14 is a schematic configuration diagram of an image forming apparatus according to a second embodiment of the present invention.

 FIG. 15 is a schematic configuration diagram of an image forming apparatus according to a third embodiment of the present invention.

 FIG. 16 is a schematic configuration diagram of an image forming apparatus according to a fourth embodiment of the present invention.

 FIG. 17 is a schematic configuration diagram of an image forming apparatus according to a fifth embodiment of the present invention.

 BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic configuration diagram of a color image forming apparatus to which the first embodiment of the present invention is applied, FIG. 2 is a schematic perspective view of a pre-wetting apparatus used in the image forming apparatus shown in FIG. 1, and FIG. FIG. 1 is a diagram for explaining the operation of the image forming apparatus shown in FIG. 1, FIG. 4 is a diagram for explaining the operation of the preset device shown in FIG. 2, and FIG. Components on photosensitive drum FIG. 1 is a view showing the flow of a pre-jet liquid when the color image forming apparatus is brought into contact with a color image forming apparatus 1 according to a first embodiment of the present invention, as shown in FIG. The photosensitive drum 10, a presetting device 20 for applying a preset liquid onto the photosensitive drum 10, a charging device 30 for charging the photosensitive drum 10, and a photosensitive drum 10. An exposure device 40 for exposing the image and a developing device 50 for developing the electrostatic latent image by supplying a toner to a portion of the photosensitive drum 10 where the electrostatic latent image is formed. A transfer device 60 that transfers and fixes the toner on the photosensitive drum 10 to predetermined paper, and a paper feeder 610 that conveys the predetermined paper to the transfer device 60; and a photosensitive drum 10. A cleaning device 70 that removes toner remaining on the top and a static eliminator 8 that removes electricity from the charged photosensitive drum 10 0 is provided.

 The charging device 30, the exposure device 40, the paper feeding device 610, the cleaning device 70, and the static eliminator 80 are based on the conventional technology used in the conventional electrophotographic printer. Can be diverted in most cases. Therefore, in the first embodiment, the description of each of the above-described devices will be omitted, and a description will be given of the plotting device 20, the developing device 50, and the transfer device 60, which are main parts of the present invention. .

As shown in FIG. 2, the pre-wetting device 20 is a plate-shaped pre-jet liquid supply member 20 having substantially the same length as the image width drawn on the photosensitive drum 10. 2 and the A case 204 for storing the supply member 202, a tank 206 for storing the split liquid 220, and a pre-wet stored in the tank 206 See the pump 208 for pumping the liquid 220, the tubes 210a and 210b, and the displacement device 212.

A material having a three-dimensional network structure in which pores are continuous, for example, Verui Isuzu (registered trademark: Kanebo Corporation) is used for the split liquid supply member 202. Beruy 夕 is a continuous porous material having a three-dimensional network structure in which pores are continuous, and can hold the pre-wetting liquid 220 by the volume of the pores and exceeds the volume of the pores When the feed liquid 220 is supplied, the feed liquid 220 is uniformly distributed in a direction perpendicular to the flow direction of the feed liquid 220. Can be released. An opening 2 is formed on the surface of the case 204 facing the photosensitive drum 10 so that the bottom surface of the print liquid supply member 202 can be brought into contact with the photosensitive drum 10. 04 a is provided (see Fig. 4). The tube 210a is connected to the supply side 220a of the pipette liquid supply member 202 with the pipette liquid 220 pumped by the pump 208. Transport. A space 204 b is formed between the supply side 202 a of the split liquid supply member 202 and the case 204, and the pre-wet After the storage solution 220 is stored in this space portion 204b, it is supplied from the supply side 202a. The tube 21 Ob is used for discharging the pre-wet discharged from the discharge side 202 b of the pre-wet liquid supply member 202. The solution 222 is transported to the tank 206. When no external signal is input, the displacement device 2 1 2

4 As shown in FIG. 4 (A), when the pre-pipe liquid supply member 202 is held at a position away from the photosensitive drum 10 and an external signal is input, as shown in FIG. As shown in B), the preset liquid supply member 202 is brought into contact with the photosensitive drum 10.

 The developing device 50 includes a developing belt which is a developer support.

 5 10 and drive rollers 5 12 a and 5 12 b which rotate the developing belt 5 10 and hold a part of the developing belt 5 10 so as to contact the photosensitive drum 10. , 512c and. A developer supply device 51, and a cleaning blade (not shown) for removing the developer adhered to the developing belt 510 after development.

 The developer supply device 51 has four developing cartridges.

51 a, 51 b, 51 c, 51 d (hereinafter, also simply referred to as a developing cartridge) are fixed to the rotating shaft 509. Each developing cartridge is brought into contact with the tank 502, the discharge roller 502a provided at the discharge port of the tank 502, and the discharge roller 502a. And a coating roller 506 provided so as to be in contact with the supply roller 504. The tank 502 of the developing cartridge 51a has a liquid developer 508a containing yellow toner, and the tank 502 of the developing cartridge 51b has a tank 502. Liquid developer 508b containing magenta toner The liquid cartridge 508 containing cyan toner is placed in the tank 502 of the developing cartridge 51c and the tank 52d of the developing cartridge 51d. Liquid developer 508 d containing black toner is stored in block 502 (hereinafter, liquid developers 508 a, 508 b, 508 c, 508). d is also simply called liquid developer).

 The discharge roller 502 a conveys the liquid developer stored in the tank 502 to the supply roller 504 by rotating in the opposite direction to the rotation direction of the supply roller 504. . The supply roller 504 rotates in a direction opposite to the rotation direction of the application roller 506, and is supplied to the surface of the application roller 506 by a discharge roller 502a. Conveys liquid developer 508. The application roller 506 rotates in a direction opposite to the rotation direction of the developing belt 510, so that the liquid supplied from the supply roller 504 to the surface of the developing belt 510 is rotated. Apply developer. The reason why the supply roller 504 and the application roller 506 were used to supply the liquid developer to the developing belt 510 is that, as described later, in the first embodiment, the toner is one in the liquid developer. This is because a high-concentration dispersion was used, so that a small amount of the developer had to be applied to the surface of the developing belt 510 thinly and evenly. One or more transport rollers for transporting the liquid developer may be provided between the supply roller 504 and the application roller 506. In this case, the distribution of the developer on the developer support 510 becomes more uniform.

The supply device 51 having the above configuration rotates the rotating shaft 509. By bringing the application roller 506 of any of the developing cartridges into contact with the developing belt 510, the developing belt 510 has a liquid containing a toner of a desired color. Apply developer.

The developing belt 5 10 is rotated in the opposite direction to the rotation direction of the photosensitive drum 10 by the driving rollers 5 12 a and 5 12 b 5 12 c, so that the photosensitive drum is rotated. The liquid developer applied by the application port 506 on the surface of 10 is conveyed. As the developing belt 510, a flexible belt-shaped member such as a resin nickel belt such as a seamless nickel belt or a polyimide film belt is used. As a result, the contact pressure when the liquid developer layer formed on the current belt 510 and the pellet liquid layer formed on the photosensitive drum 10 come into contact with each other is reduced. Since it can be dispersed, the liquid developer layer formed on the developing belt 510 and the split liquid layer formed on the photosensitive drum 10 are maintained in a two-layer state. And the two can be separated inside the split liquid layer. The developing belt 510 must be capable of applying an electric developing bias. Therefore, when using a resin belt, it is necessary to add conductive fine particles to lower the electric resistance value, or to conduct conductive processing on the surface of the belt. If the belt itself has conductivity, a rubber roller having a low electric resistance is applied to the drive rollers 51 a, 51 b, and 512 c so that a developing bias can be applied. Is used. Conductive on belt surface If processing is performed, a conductor that contacts the belt surface is provided, and a developing bias is applied to this conductor.

 The transfer device 60 includes an intermediate transfer belt 602 which is an intermediate transfer member, and drive rollers 604a, 604b, and 604c for rotating the intermediate transfer belt 602. Holds a part of the intermediate transfer belt 602 so as to be in contact with the photosensitive drum 10. π —Laters 605a, 605b and abuts the intermediate transfer belt 602. The secondary transfer rollers 606 and ¾ are provided as follows.

 The intermediate transfer belt 602 is rotated in a direction opposite to the rotation direction of the photosensitive drum 10 by drive rollers 604a, 604b, 604c. For the intermediate transfer belt 602, a flexible belt-shaped member such as a resin belt such as a polyimide film belt, a PET film belt, or a rubber belt is used. Can be Thereby, the contact pressure when the toner image formed on the photosensitive drum 10 and the intermediate transfer belt 602 come into contact can be dispersed.

Here, the primary transfer and the secondary transfer are performed by electrostatic force. The transfer device 60 includes an intermediate transfer belt 602 as an intermediate transfer body that can be charged, and a corona discharger 6 that is charged with a charge having a polarity opposite to that of the toner image on the intermediate transfer belt. 07, and the rollers supporting the intermediate transfer belt are grounded via high-resistance elements. Also, a power supply device that can charge the secondary transfer roller 606 and applies a bias voltage to the secondary transfer roller. 6 0 9 is provided. The secondary transfer roller 606 rotates in contact with the intermediate transfer belt 602 when the portion of the intermediate transfer belt 602 on which the toner image has been formed comes along with the paper, When this part passes, it leaves.

 Instead of charging the intermediate transfer belt 602 with the corona discharger 607 for the primary transfer, the power supply 621 is supplied to the drive roller 604a and the holding roller 605a. The connection voltage may be configured to be applied. During the primary transfer, a bias having the opposite polarity to that of the toner is applied to the intermediate transfer member. Ground during the secondary transfer. Further, a fixing device 620 provided with a fixing roller 622 incorporating a fixing heater 624 is provided. The intermediate transfer belt 602 is made of resin such as polyimide, PET, or rubber or metal. When corona discharge is used for the primary transfer, it is necessary to ensure the electrical conductivity of the intermediate transfer belt 602, so when using a resin material for the belt, conductive particles are added to reduce the electrical resistance. Lower or apply conductive processing to the belt surface. Belt resistance is

10 ³ to 10 ¹² Ω · cm, especially 10 ⁸ to 10 '. Ω · cm is preferred. Further, arbitrary preferable is ^{1 0 6 ~ 1 0 8 Ω} · cm in the case of applying a direct bias to the roller in the primary transfer. On the intermediate transfer belt 602, a surface layer such as Teflon or silicon having a good releasability is formed. This is to reduce the physical adhesion of the toner and facilitate the transfer of the toner to the paper. Also, since the secondary transfer roller 606 applies a transfer bias voltage, it has conductivity such as metal, conductive rubber, or the like. Material is used. The surface of the secondary transfer roller 606 is provided with a fluorine coating to easily remove toner adhered to the surface and to prevent the secondary transfer roller from being stained.

Next, an image forming material used in the first embodiment of the present invention will be described. The liquid developer used in the first embodiment includes a resin serving as a binder such as epoxy, a charge control agent that applies a predetermined charge to the toner, a coloring pigment, and a dispersant that uniformly disperses the toner. Consists of toner and carrier liquid. The composition of the toner is basically the same as that used in conventional liquid developers, but their formulations have been changed to be compatible with silicone oil in order to adjust charging characteristics and dispersibility. It is. The smaller the average particle diameter of the toner, the better the resolution. However, if the average particle diameter of the toner is small, the physical adhesive strength is increased, and it is difficult to remove the toner when transferring. For this reason, in the first embodiment, the average particle diameter of the toner is adjusted to be centered at about 2 to 4 zm for the purpose of improving transferability. It depends on the carrier solution, resin, coloring pigment, charge control agent, etc. used and their concentrations. In the first embodiment, an experiment was conducted by changing the viscosity from 50 to 600 mPa-s-toner concentration in the range from 5 to 40%. As the carrier liquid, a liquid having a low viscosity such as dimethylpolysiloxane oil or cyclic polysiloxane oil exhibiting high electric resistance is used. Since the liquid developer layer formed on the developing belt 5100 is formed in a thin layer, the liquid developer layer Since the amount of carrier liquid contained in the developer layer is extremely small, the amount of carrier liquid contained in the liquid developer supplied to the latent image surface of the photosensitive drum 10 is also extremely small. Therefore, the carrier liquid absorbed by paper or the like at the time of transfer is extremely small, and if the viscosity is 100 OmPa-s or less, almost no carrier liquid remains after fixing. can not see. According to experiments conducted by the present inventors, the carrier liquid has a viscosity of 2.5 mPa · s, DC344 of Dow Corning, USA, and a viscosity of 6.5 mPa · s. · When carrying out image output experiments using DC 345 from Dow Corning, Inc. of the United States, no carrier liquid remained on the paper after fixing in any case. However, because of its high volatility, it became necessary to make the developing device a closed structure. Furthermore, when an image output experiment was performed using Shin-Etsu Silicon KF-96-20, which has a carrier liquid viscosity of 20 mPa · s, it was printed on paper after fixing. No residual carrier liquid was seen. Also, since the volatility was not so high, there was no need to make the developing device a sealed structure. DC344, DC345 and KF-966-20 are generally used in cosmetics and have high toxicity and safety. There are many other types of carrier liquid, such as Shin-Etsu Silicone's KF 9937, and any of them can be used as long as the electrical resistance, evaporation characteristics, surface tension, safety, etc. are satisfied. You may choose.

Further, in experiments conducted by the inventors, fog and toner lumps may adhere when surface tension is large. Experimentally, it was found that problems were likely to occur in image quality when the surface tension was 21 dyn / cm or more.

It is the electrical resistance, toner charging stability problems there Ri, 1 0 ¹⁴ Ω cm or desired arbitrary. Minimum ¹ 0 1 ² Ω cm or more is required. In the description of the first embodiment, an example using DC345, which is inexpensive and easily available, is shown in view of the results of these experiments.

 The pre-wet solution does not disturb the electrostatic latent image formed on the image support, evaporates easily at the time of fixing, and does not adhere to the fog toner. Is required. Examples include Dow Corning's DC334,

DC200-0.65, -1.0, -2.0, KF966L-1 and KF9393 from Shin-Etsu Silicon Co., Ltd. are examples. In general, it is necessary to select highly evaporable silicone oil.

In an experiment conducted by the 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 mPas, but from 5 mPas At about 6 mPa · s, there was a tendency for time and temperature to be required for drying the liquid at the time of fixing. At 10 mPa · s, the energy required for drying is too large and is not common. In addition, if it is less than 0.5 mPa · s, the volatility becomes high, so it is not appropriate because it is subject to legal regulations as dangerous goods. Also, due to the effect of heating the paper, the boiling point must be below 250 ° C. The surface tension is preferably as low as possible in order to eliminate the adhesive force between the developer and the image support, improve the releasability, prevent image stains and fogging, and improve the resolution of image quality. According to the experiments by the present inventors, the limit is about 20 to 21 dyn / cm, and it is necessary to select one lower than this.

If the electrical resistance is low, it leaks the latent image charge and blurs the image. Therefore, it is necessary to use the highest possible one. Experimental The ¹ 0 1 ⁴ Ω cm approximately above the desired correct minimum ¹ 0 1 ² Ω cm is required.

 Next, the operation of the image forming apparatus according to the first embodiment of the present invention will be described. First, as shown in FIG. 3A, the surface of the photosensitive drum 10 is charged by the charging device 30. Generally, a corona discharger is used for the charging device 30. Next, an image is exposed on the charged photosensitive drum 10 by the exposure device 40. For example, an image is exposed by a laser scanner to form an electrostatic latent image on the surface of the photosensitive drum 10. As shown in Fig. 3 (B), the part exposed to the light from the laser and the scanner becomes conductive and loses the charge, and the part not exposed to the light is the electrostatic latent image that is the image of the charge. It remains as an image.

Next, as shown in FIG. 3 (C), the pre-jetting liquid 220 is applied to the photosensitive drum 10 by the pre-wetting device 20. When an external signal is input, the presetting device 20 brings the preset liquid supply member 202 into contact with the photosensitive drum 10. The inside of the pre-jet liquid supply member 202 is supplied with a pre-wet liquid 2 by a pump 208. 20 is constantly circulating, and as shown in FIG. 5, the split liquid 220, which is the split liquid supply member 202, exceeds the volume of the pores of Verui overnight. It is released from the discharge side 202 b of the print liquid supply member 202 and is discharged from the bottom surface of the print liquid supply member 202, damaging the photosensitive drum 10. It is evenly applied on the photosensitive drum 10.

 Next, the electrostatic latent image is visualized by the developing device 50. The liquid developer discharged from the tank 502 by the discharge roller 502 a and supplied to the supply roller 504 is conveyed to the application roller 506, and then is discharged to the developing belt 5. A thin layer is formed on the development belt 510 by being applied thinly and evenly on 10. By rotating the developing cartridge, it is possible to apply a liquid developer containing any of yellow, magenta, cyan and black toner to the developing belt 510. it can. The liquid developer layer formed on the developing belt 5100 in this manner is brought close to the electrostatic latent image formed on the surface of the photosensitive drum 10 as shown in FIG. 3 (D). Then, the charged toner is moved onto the photosensitive drum 10 by an electrostatic force to form a toner image.

 Next, the toner image formed on the photoreceptor 10 is primarily transferred to an intermediate transfer belt 602 as an intermediate transfer member by the transfer device 60. The toner image formed on photoconductor 10 is

3 As shown in (E), the toner image formed on the photoreceptor 10 and the corona discharger 607 or the voltage applied Intermediate transfer belt 60 is generated by electrostatic force generated between drive belt 604 a and transfer belt 602 charged with a charge having a polarity opposite to that of toner by holding roller 605 a. 2 Moves up and is transcribed. On the other hand, the photoreceptor 10 is cleaned by the cleaning device 70 to remove the liquid developer 508 remaining on the photoreceptor 10, and thereafter, is discharged by the discharger 80. Then, the developing cartridge 51 rotates, and the cycle from charging to static elimination as described above is repeated again, whereby yellow, magenta, cyan, and yellow are placed on the intermediate transfer belt 602. Transfers black toner images one after another. As a result, a toner image corresponding to the colorization is formed on the transfer belt 602.

 Next, the transfer device 60 secondarily transfers the toner image corresponding to the color formed on the intermediate transfer belt 602 to paper as a recording medium. The toner image corresponding to the color formed on the intermediate transfer belt 602 is applied to the secondary transfer roller 606 by a power supply device as shown in FIG. 3 (F). The electric field generated by the applied bias voltage causes the paper to be conveyed by the paper feeder 610 and fed onto the paper fed between the intermediate transfer belt 602 and the secondary transfer roller 606. It moves and is transcribed. The transferred toner is thermally melted and fixed by the fixing heater 624 provided in the fixing roller 622 of the fixing device 620. This makes it possible to form a color image on paper.

6 to 10 show the developing process of the first embodiment of the present invention. Fig. 6 is a diagram for explaining the whole development process, Fig. 7 is a diagram showing the approach process, and Fig. 8 is a diagram showing the toner transfer process. FIG. 9 is a diagram illustrating a separation process of a non-image portion, and FIG. 10 is a diagram illustrating a separation process of an image portion. Unlike the conventional developing process, the developing process of the first embodiment includes, as shown in FIG. 6, an approaching process in which the developing belt approaches the photosensitive drum and the liquid developer approaches the photosensitive drum surface. The liquid developer layer and the pre-wet liquid layer are soft-contacted and the toner moves.The toner moving process and the toner that separates from the photosensitive drum and adheres to the developing belt It is considered to be composed of three processes, namely, the separation process in which the toner is separated from the toner on the photosensitive drum.o

 In the approaching process, as shown in FIG. 7, the developing belt 510 is formed of a flexible belt-shaped member as shown in FIG. 7, so that the developing belt 510 and the photosensitive drum 10 are connected to each other. A minute gap, that is, an interval d, is formed between the liquid developer and the high-viscosity liquid developer composed of the carrier liquid and the toner, and the print liquid are soft-contacted. As a result, the pre-wet liquid having a low viscosity is slightly extruded back and forth, so that no pre-wet liquid pool is generated and O

In the toner transfer process, as shown in FIG. 8, in the image area, the toner is mainly cooled by the electric field formed between the charge on the photosensitive drum 10 and the developing belt 5 10. It moves to the latent image surface by passing through the pre-wet liquid layer due to the force of the liquid. on the other hand, The toner in the non-image area is basically an unnecessary toner photosensitive drum 10 because the surface of the photosensitive drum 10 and the liquid developer layer are separated by a split liquid layer. No sticking to the surface occurs.

 In the separation process, the liquid developer basically remains on the developing belt 510 in the non-image area as shown in FIG. At the interface between the pre-wet liquid layer and the liquid developer layer, when the two layers separate, a part of the low-viscosity pre-wet liquid layer transfers to the liquid developer layer and separates. Therefore, the separation point between the two layers is considered to be inside the prewetting liquid layer. On the other hand, in the image area, the toner moved to the surface of the photosensitive drum 10 pushes the pre-wet liquid layer as shown in FIG. Located on a layer and separates within that layer. A part of the carrier liquid and a part of the pre-wet liquid form a layer on the developing belt 510 after the toner has moved.

FIG. 11 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 liquid developer has a high viscosity, so it may move from the developing belt 510 to the surface of the photosensitive drum 10 by electrostatic force. The toner group forms a cluster without breaking the viscosity of the toner located around the toner group, and moves to the surface of the photosensitive drum 10, so that excessive toner adhesion occurs. Image noise occurs. In order to suppress the occurrence of this cluster, the liquid developer layer thickness must be sufficiently developed. It must be kept to the minimum value possible.

 FIG. 12 is a diagram showing a state in which the developing roller and the photosensitive drum, which are the developing support, are hard contacted.

FIG. 3 is a diagram for explaining a soft contact of the first embodiment. As described above, in the developing process of the first embodiment, the function relating to image formation of the pre-wet liquid layer is important. Therefore, an important requirement in the development process is to maintain the state of the two layers, ie, the pre-liquid layer and the liquid developer layer. If the developing roller and the photosensitive drum are hard-contacted as shown in FIG. 12, the two-layer state cannot be maintained, so in the first embodiment, as shown in FIG. 13, By using the developing belt 510 made of a flexible belt-like member as a developer support, the pre-dipped liquid layer on the photosensitive drum 10 and the developing belt When the liquid developer layer on the top of the photosensitive drum 10 comes into contact, a small gap d is formed between the surface of the photosensitive drum 10 on which the electrostatic latent image is formed and the developing belt 5 10. To be formed.

Next, the optimization of the layer thickness of the liquid developer layer, the layer thickness of the briunit liquid layer, and the developing gap will be described. The thickness of the liquid developer layer needs to be thinner when the viscosity of the liquid developer is 50 mPas or more, especially when it is 500 mPas or more. Ideally, the thickness is a little thicker than the layer thickness that satisfies the amount of toner development required during development (that is, the density when solid black is produced). This is because when using a liquid developer with high viscosity, it is electrostatically selected during development. This is because excess toner is attracted to the photosensitive drum and moved onto the photosensitive drum due to the viscosity of the liquid, causing abnormal toner attachment and image contamination. In experiments conducted by the inventors, a good image was obtained with a liquid developer having a high toner concentration at a layer thickness of about 5 μm to 40 μm at a low toner concentration. 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 about 8 to 20 / m.

 There is an optimum value for the thickness of the split liquid layer depending on the viscosity and surface tension of the selected split liquid. If it is too thin, the high-viscosity liquid developer will adhere irregularly on the photosensitive drum, causing image stains. As the amount of pre-wetting liquid is increased, the image stain is improved and the optimum value is confirmed. As the amount is further increased, the charge of the latent image flows, resulting in a reduction in sharpness and resolution, and a toner flow during development, which also tends to blur the image. In the experiment using DC344, good results were obtained with a thickness of 30 ^ 111 or less, especially 20/11 or less. For less viscous materials, good results can be obtained with thinner and thicker materials. However, for high viscosities, the optimal values tend to be narrower.

The narrower the gap between the photosensitive drum and the developing belt, the better the resolution and the uniformity of the density of the solid part in the image quality are the same as the conventional developing method. The high-viscosity liquid developer used in the first embodiment has a strong cohesive force between toners, Unlike a body developer, the phenomenon that toner released from a developer support or carrier particles by a mechanical shock or electrostatic force is not used for development does not occur. That is, development is not performed with an air layer interposed between the liquid developer layer and the photosensitive drum. Therefore, the developing belt and the liquid developer layer, the liquid developer layer and the pre-jet liquid layer, and the pre-wet liquid layer and the photosensitive drum are in contact with each other. Is required. Therefore, the developing gap d must be smaller than the thickness of the liquid developer layer and the pre-wet liquid layer, but not so as to disturb each layer. In the first embodiment, the distance is set between 8 μm and 50 m according to the difference in the viscosity of the liquid developer and the toner concentration.

Table 1 shows the results of image extraction and experiments performed under the above conditions. From these results, the optimum range of the viscosity of the developer and the pre-wet solution for the developing method of the first embodiment is from 100 mPa · s to 600 mPa · s for the developer. It was found that the pre-wet solution was between 0.5 mPa · s and 5 mPa · s. The image quality varies depending on the thickness of the liquid developer layer on the developing belt, the thickness of the pre-wet liquid layer, the image gap, etc. Even after optimization, the tendency was generally as shown in Table 1, and it was confirmed that the optimal region of the liquid developer was within the range shown in Table 1. The silicone oil used for the pre-wetting solution was DC 200 series manufactured by Dakogung Co., Ltd., and the carrier fluid for the developing solution was used for the silicone oil. DC 345 was used.

Viscosity of pre-wet liquid (mPas)

(mPa-s) Toner concentration 0.65 1.5 3.0 5.0 10

 (X)

50 Image density tends to be low,

 Dispersion stability of toner slightly deteriorates

100 10 Slightly lower concentration

 Residual on paper Residual on paper

500 20 Evaporation of oil

1000 22 is slow. Is practical both in density and resolution

 Practically too slow Good image quality is obtained.

 2000 25 limit. You.

3000 30

6000 40

In the image forming apparatus thus configured, the toner image attached to the surface of the image support 10 and charged to a predetermined polarity is pulled by the electrostatic force of the charge on the surface of the intermediate transfer belt 62. Then, primary transfer is performed on the surface of the intermediate transfer belt. On the other hand, the paper as the recording medium is conveyed by the paper feeder 610 and is sandwiched between the intermediate transfer belt 602 and the secondary transfer roller 606. Here, the toner image on the intermediate transfer belt moves to the paper by the electrostatic force of the secondary transfer roller and is secondary-transferred. The recording paper with the toner image attached thereto is sent to the fixing device 62 and the transferred toner is thermally melted by the fixing heater 62 provided in the fixing roller 62 so that the toner is fused onto the recording paper. Establish. Thus, a color image can be formed on paper.

 Conventional liquid developers are generally used as carrier liquids.

Isopar G (registered trademark: manufactured by Exon) is used. Since the resistance value of Isopar is not as high as that of silicon oil, when the toner concentration is increased, that is, when the distance between the particles is reduced, the chargeability of the toner is deteriorated. Therefore, in the case of Isopar, the toner concentration is limited. On the other hand, since the silicon oil used in the first embodiment has a sufficiently large resistance value, the toner concentration can be increased. In general, in the case of Isopar, the toner is in a good dispersion state, and therefore, even when the toner concentration is 1 to 2%, the toner particles repel each other, so that the toner is uniformly dispersed. On the other hand, when the concentration of toner is 1 to 2%, silicone oil does not disperse well and precipitates soon. However, when the toner concentration is 5 to 40%, the toner is densely packed and stably dispersed. For this reason, in the first embodiment, a high-viscosity liquid developer in which the toner is dispersed at a high density is used. As a result, the amount of the developing solution can be significantly reduced as compared with the conventional low-concentration liquid developer, and the size of the apparatus can be reduced. Furthermore, since the liquid developer of the first embodiment is a high-viscosity liquid, it is easier to store and handle than the conventional low-viscosity liquid developer and powder developer.

 As described above, Isopar, which has been used in conventional liquid developers, has a high volatility and emits a foul odor, so that not only the working environment is deteriorated, but also pollution is caused. In contrast, the silicone oil used in the first embodiment is a safe liquid and odorless, as is clear from the fact that it is used for cosmetics. According to the first embodiment, however, the working environment can be improved and there is no problem of pollution.

 In the first embodiment, the developing device using the developing belt 510 made of a flexible belt-like member for the developer support has been described as the developing device. The developing device is not limited to this, and the developing device may use a developing roller formed of a conductive member such as a metal on a developer support. However, the liquid developer layer formed on the developing roller and the pre-wet liquid layer formed on the photosensitive drum are brought into contact with each other while maintaining a two-layer state, and both are brought into contact with the pre-jet liquid. A flexible belt-like member or an elastic roller is used for the image support to separate the layers inside the layer, or the developing roller is a small gap between the developing roller and the photosensitive drum. It must be arranged so as to form d.

Next, a second embodiment of the present invention will be described with reference to FIGS. explain. FIG. 14 is a schematic configuration diagram of an image forming apparatus to which the transfer method according to the second embodiment of the present invention is applied. In the image forming apparatus shown in FIG. 14, those having the same functions as those of the first embodiment are given the same reference numerals or corresponding reference numerals, and the detailed description thereof will be omitted. .

 An image forming apparatus 2 according to a second embodiment of the present invention is different from that of the first embodiment in that, as shown in FIG. 14, a photosensitive belt 1 is used instead of a photosensitive drum 10 serving as an image support. 2 is held by the drive rollers 122a, 122b, 122c and rotated, and the transfer device 64 is used instead of the transfer device 60. is there.

As the base material of the photosensitive belt 12, a flexible belt-shaped member such as a resin nickel belt such as a seamless nickel belt or a polyimide film belt is used. This makes it possible to disperse the contact pressure when the toner image formed on the photosensitive belt 12 and the intermediate transfer member come into contact with each other. The difference from the transfer device 60 of the embodiment is that an intermediate transfer drum 642 is used in place of the intermediate transfer belt 602 as an intermediate transfer member. The intermediate transfer drum 642 is provided so as to be in contact with the photosensitive belt 12, and rotates in a direction opposite to the rotation direction of the photosensitive belt 12. In addition, a voltage can be applied to the intermediate transfer drum 642 by a DC power supply. The toner on the photosensitive belt 12 is moved onto the intermediate transfer drum 642 by the electrostatic force generated by the voltage application. The transfer device 64 configured as described above primarily transfers the toner image formed on the photosensitive belt 12 onto the intermediate transfer drum 642 by electrostatic force on the surface of the intermediate transfer drum 642. The yellow, magenta cyan, and black toner images are successively superimposed and transferred onto the intermediate transfer drum 642, so that the toner images are integrated on the intermediate transfer drum 642. After forming the corresponding toner image, the toner image corresponding to this coloration is conveyed by the paper feeder 6110 and is transferred between the intermediate transfer drum 642 and the secondary transfer roller 63. The image is secondarily transferred to a sheet of recording medium fed in between, and is further fixed by a fixing device 62. The other operations of the electrostatic latent image liquid developing device according to the second embodiment are the same as those of the first embodiment, and thus detailed description thereof will be omitted.

 According to the second embodiment of the present invention, since the photosensitive belt 12 composed of a flexible member is used for the image support, the photosensitive belt 12 is formed on the latent image surface of the photosensitive belt 12. Since the contact pressure when the toner image thus formed contacts the intermediate transfer drum 642 can be dispersed, the toner image is not disturbed as in the first embodiment. Primary transfer to 6 4 2 is possible. Other effects are the same as those of the first embodiment.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 15 is a schematic configuration diagram of an image forming apparatus according to a third embodiment of the present invention. Note that the image forming apparatus of the third embodiment has the same functions as those of the first embodiment. Are given the same reference numerals or corresponding reference numerals, and their detailed description is omitted.

 The image forming apparatus 3 of the third embodiment is different from that of the first embodiment in that a photosensitive belt 12 used in the apparatus of the second embodiment is used instead of the photosensitive drum 10 as an image support. This is, as in the second embodiment, held by the driving rollers 122a, 122b, 122c and rotated and driven. The other operations of the image liquid developing device are the same as those of the first embodiment, and thus the detailed description thereof is omitted.

 According to the third embodiment of the present invention, the photosensitive belt 12 composed of a flexible belt-shaped member is used for the image support, and further, the intermediate belt has a flexible belt. By using the intermediate transfer belt 602 made of a shape-like member, the toner image formed on the latent image surface of the photosensitive belt 12 and the intermediate transfer belt 602 are formed. Since the contact pressure at the time of contact can be further dispersed, the toner image can be transferred to the intermediate transfer belt 602 without disturbing the toner image. Other effects are the same as those of the first embodiment.

Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 16 is a schematic configuration diagram of an image forming apparatus according to a fourth embodiment of the present invention. In the image forming apparatus of the fourth embodiment, those having the same functions as those of the first embodiment are denoted by the same reference numerals or corresponding reference numerals, and a detailed description thereof will be omitted. . Here, a release layer is formed on the surface of the intermediate transfer belt 62. As a result, the toner on the photosensitive drum 10 is moved onto the intermediate transfer belt 602 by the electrostatic force. The belt configuration and surface properties are as described above.

 In the secondary transfer step, the heating roller 603 is immersed in the intermediate transfer belt 602, contacts the intermediate transfer belt, and rotates in the same direction. The heating roller 603 has a heater 625 for heating the intermediate transfer belt 602 and heating the toner on the belt. The toner on the intermediate transfer belt is melted by the heating roller 603, and the paper is fed by the secondary transfer roller 606 rotating in the opposite direction to the rotation direction of the intermediate transfer belt 602. The sheet is pressed by the intermediate transfer belt 6102 via the paper conveyed by the apparatus 6101. Further, a fixing heater 623 for heating the roller may be provided inside the secondary transfer roller 606. A nitrogen lamp is used for the berth. The surface of the secondary transfer roller 606 is provided with a fluorine coating. This improves the releasability of the toner from the toner. By means of the following, the toner adhered to the secondary transfer roller 606 is easily removed, and the contamination of the secondary transfer roller 606 is prevented. This is to prevent it.

 Since the intermediate transfer belt 602 receives heat, a material having heat resistance, such as a polyimide film, is used.

According to the fourth embodiment of the present invention, The toner image is primarily transferred onto the intermediate transfer belt 602 using electrostatic force, and then the toner image primarily transferred onto the intermediate transfer belt 602 is intermediately transferred by the secondary transfer roller 606. The secondary transfer onto the paper is performed by using the pressing force to the belt 602 and the heat from the fixing heater 625, and at the same time, the fixing is performed. This eliminates the need to wet the paper with a pre-wetting solution to treat the surface of the paper in order to improve the transferability. Therefore, the toner image formed on the photosensitive drum 10 can be removed. It can be transferred to paper without being affected by the surface roughness of the paper or the water absorption of the split solution. In addition, since the heating roller is in contact with the inside of the intermediate transfer belt, it is possible to effectively melt the toner. Here, the heating element is a halogen lamp, but a ceramic heater may be used to increase the heating rate of the heating element.

 Further, according to the fourth embodiment, the intermediate transfer belt 60 2 formed of a flexible belt-shaped member is used for the intermediate transfer body, so that the latent image on the photosensitive drum 10 is used. Since the contact pressure when the toner image formed on the surface and the intermediate transfer belt 602 come into contact can be dispersed, the toner image transferred onto the intermediate transfer belt 602 can be dispersed. Disturbance can be prevented.

Further, according to the fourth embodiment, by heating the secondary transfer roller 603, the toner image primarily transferred on the intermediate transfer belt 602 is secondarily transferred to paper. At the same time, it is melted and fixed on paper, so the transfer device and the fixing device are integrated. Therefore, the size of the device can be reduced.

 Further, the contact pressure when the toner image formed on the latent image surface comes into contact with the intermediate transfer belt 602 can be further dispersed, so that the intermediate transfer belt is not disturbed without disturbing the toner image. Can be transferred to Belt 602. Other effects are the same as those of the first embodiment.

 Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 17 is a schematic configuration diagram of an image forming apparatus according to a fifth embodiment of the present invention. In the image forming apparatus of the fifth embodiment, those having the same functions as those of the first embodiment are given the same reference numerals or corresponding reference numerals, and the detailed description is omitted. .

 Here, an adhesive diagram is formed on the surface of the intermediate transfer belt 602.

 A drying device 630 for drying the toner image formed on the surface of the photosensitive drum between the developing device 1 and the transfer device 60 on the periphery of the photosensitive drum 10 is provided. If the surface of the photoreceptor is wet during the primary transfer, transfer cannot be performed due to the adhesive force.However, if the toner image on the photosensitive drum is dried by the More effective primary transfer becomes possible.

As a result, the toner on the photosensitive drum 10 is moved onto the intermediate transfer belt 602 by the physical adhesion to the intermediate transfer belt 602 instead of the electrostatic force. The adhesive layer of the intermediate transfer belt 602 is made of a rubber material such as natural rubber, urethane rubber, styrene-butadiene rubber, silicone rubber, fluorine-containing silicon rubber, or fluorine rubber. It is formed by Silicon rubber includes methyl silicone rubber, methyl phenyl silicone rubber, methyl vinyl silicone rubber, methyl phenol vinyl silicone rubber, and fluoro silicone rubber. These are KE-42, KE12, KE-44, KE-130, KE-180, FE-123 (all manufactured by Shin-Etsu Chemical Co., Ltd.) It is commercially available as. In particular, fluorosilicone rubber is a suitable material for secondary transfer by heating the recording medium because the releasability from the toner increases as the temperature rises. . Since fluorosilicone does not swell in silicone oil, it is also suitable when silicone oil is used as an insulating liquid of a liquid developer.

 Examples of the fluorine-containing silicone rubber include 1,1,1-triphenylene propylmethylsiloxane rubber.

It is marketed as SilasticLS (manufactured by Dow Corning). Fluoro rubber includes vinylidene fluoride—6 propene rubber, vinylidene fluoride monochloride—3—fluorocarbon rubber, etc., and these are Daiel G—5. 01, Daiel G-701 (both manufactured by Daikin Industries, Ltd.).

The fifth embodiment is different from the fourth embodiment in that the first transfer does not use electrostatic force, and an adhesive layer is provided on the surface of the intermediate transfer belt. There is no difference in the method and apparatus of the secondary transfer, as the transfer is performed by the adhesive force.

 According to the fifth embodiment of the present invention, the toner image formed on the photosensitive drum 10 is transferred to the intermediate transfer belt 60 by utilizing the adhesive force of the adhesive layer on the surface of the intermediate transfer belt 62. The toner image primary-transferred onto the intermediate transfer belt 602 and then transferred onto the intermediate transfer belt 602 is pressed by the secondary transfer roller 606 onto the intermediate transfer belt 62 and the fixing heater 62 Uses heat from step 3 for secondary transfer onto paper and fixing at the same time. As a result, the toner image formed on the photosensitive drum 10 can be transferred onto paper without using electrostatic force. There is no need to treat the paper surface by wetting it with the setting solution, and therefore, the toner image formed on the photosensitive drum 10 is affected by the surface roughness of the paper and the water absorption of the pre-wetting solution. It can be transferred to paper without receiving it. Also, since it is not necessary to charge the intermediate transfer belt 602 by corona discharge, no ozone is generated during transfer.

 Other functions and effects are the same as those described in the fourth embodiment.

It should be noted that the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the invention. For example, in each of the above-described embodiments, the pre-wetting device is used as a pre-wetting device by using a pre-wetting solution supply member 202 on the surface of the photosensitive drum 10. Explain what applies 2 220 However, the present invention is not limited to this, and the preset device can apply a predetermined amount of the preset liquid uniformly to the surface of the photosensitive drum. Anything is fine. For example, the coating may be performed by discharging the pre-jet liquid from a plurality of nozzles arranged in the axial direction, or may be performed by using a sponge roller or the like.

 Further, in each of the above-described embodiments, the supply device having the four developing power one-triggers has been described, but the present invention is not limited to this. The supply device may be provided with one, two or three developing cartridges for applying a liquid developer of a desired color onto a developer support.

 Further, in each of the above embodiments, the image is exposed on the charged image support by the exposure device 40, and thereafter, the image is exposed on the image support by the preset device 20. A description has been given of the case in which the pleat liquid 220 is applied, but the present invention is not limited to this, and the pre-wetting device 20 applies the image on the image support. It may be a method in which the split solution 220 is applied, and thereafter, the image is exposed on the charged image support by the exposure device 40.

Further, in each of the above embodiments, the case where the organic photosensitizer was used as the image support was described. However, the present invention is not limited to this, and the image support was obtained by the Carlson method. Even if an insulator layer is formed on a conductor that directly forms an electrostatic latent image, such as various photoreceptors to be used or ionography, etc. Good.

 Further, the present invention is not limited to the above-described embodiments, and the present invention is not limited to the case where the pre-out liquid layer is formed and the layer thickness of the liquid developer is 5 to 40 μm. The viscosity of the high-viscosity developer may be up to 1000 mPas. At present, a high-viscosity developer with a viscosity of 600 mPas or more is considered to be difficult to agitate the carrier liquid and the toner. If it becomes available, it may be 600 mPas or more. If the viscosity exceeds 1000 mPas, it becomes impractical.

Industrial applicability

As described above, according to the present invention, a toner image formed on an image support by a liquid developer containing a high concentration of toner is transferred onto a recording medium by using electrostatic force, so that high efficiency is achieved. A resolution image can be obtained. In addition, it is not necessary to wet the recording medium with a pre-wetting solution to treat the surface of the recording medium in order to improve the transferability. The toner image formed on the image support can be satisfactorily transferred onto the recording medium regardless of the water absorption of the jet liquid. Secondary transfer of the toner image primary-transferred onto the intermediate transfer member onto the recording medium using the pressing force of the second transfer member on the intermediate transfer member and the heating of the intermediate transfer member and the secondary transfer member At the same time, the fixing is performed at the same time, so that the transfer device and the fixing device can be integrated, so that the size of the device can be reduced. Like this, the book According to the present invention, it is possible to provide an image forming method which can be easily reduced in size, can reduce pollution, and can obtain a precise image.

 Further, according to one aspect of the present invention, at least one of the image support and the intermediate transfer member is formed of a flexible member, so that the image support and the intermediate transfer member are formed on the latent image surface of the image support. Since the contact pressure when the toner image formed on the intermediate transfer member comes into contact with the toner image can be dispersed, it is possible to prevent the toner image transferred on the intermediate transfer member from being disturbed. Accordingly, it is possible to provide an image forming method capable of preventing an image transferred on a recording medium from being disturbed.

 Further, according to another aspect of the present invention, the adhesive layer on the surface of the intermediate transfer body is formed of fluorosilicone rubber, and the fluorosilicone rubber is heated. Since the releasability from the toner is improved, it is possible to provide an image forming method capable of satisfactorily secondary-transferring the toner image primarily transferred on the intermediate transfer member onto a recording medium. You.

 According to still another aspect of the present invention, since the properties of the developer are predetermined, it is possible to provide an image forming method in which a liquid developer and a pre-wet solution are well compatible. it can.

 According to another aspect of the present invention, there is provided an image forming method in which silicone oil is used as an insulating liquid of a liquid developing agent, thereby reducing pollution and improving the working environment. Can be provided.

According to still another aspect of the present invention, there is provided a toner comprising: Since the thickness is 0.1 to 5 μm, it is possible to provide an image forming method in which the toner is easily removed at the time of transfer.

 According to another aspect of the present invention, it is possible to provide an image forming method capable of improving the releasability at the time of transfer since the preset liquid has a predetermined property. You.

 According to still another aspect of the present invention, since the pre-wetting liquid contains silicone oil as a main component, an image forming method capable of further reducing pollution and improving a working environment. Can be provided.

Claims

The scope of the claims 1. The electrostatic latent image formed on the image support is developed by toner, which is a charged visualization particle, and the toner image formed on the image support is recorded on a recording medium. An image forming method to be transferred,  A high-viscosity liquid developer of 100 to 1000 mPas in which toner is dispersed in a high concentration in an insulating liquid is applied to a latent image of the image support by a developer support. A developing step of forming a toner image on the image support by supplying the toner to the surface;  A primary transfer step of transferring the toner image formed on the image support onto an intermediate transfer body,  A secondary transfer step of transferring the toner image transferred on the intermediate transfer body to the recording medium by pressing the secondary transfer body against the intermediate transfer body via a recording medium. Characteristic image forming method.  2. Further, prior to the developing step, a pre-wet is applied on the image support with a pre-release solution which is a chemically inactive dielectric liquid having releasability. The image forming method according to claim 1, further comprising the steps of:  3. The image forming method according to claim 1, wherein at least one of the image support and the intermediate transfer member is formed of a flexible member. 4. The primary transfer step uses an intermediate transfer member having an adhesive layer formed on a surface that comes into contact with the image support. 2. The image forming method according to claim 1, wherein the toner image on the image support is transferred onto the intermediate transfer member by a force.  5. The image forming method according to claim 4, wherein the adhesive layer is formed of fluorosilicone rubber.  6. The image forming method according to claim 1, wherein the transfer in the primary transfer step and the secondary transfer step is performed using an electrostatic force.  7. In the primary transfer step, the toner image on the image support is transferred onto the intermediate transfer member by using the conductive intermediate transfer member to take on the polarity opposite to the polarity of the toner image. The image forming method according to claim 6, wherein  8. In the secondary transfer step, the toner image on the intermediate transfer member is transferred to the recording medium by using a conductive secondary transfer roller to have a polarity opposite to that of the toner image. The image forming method according to claim 6, wherein the image is transferred.  9. In the secondary transfer step, the toner image primary-transferred onto the intermediate transfer body is secondarily transferred to the recording medium by heating the secondary transfer body, and is simultaneously fixed. The image forming method according to claim 1, wherein the image forming method is performed.  10. The image forming method according to claim 1, wherein the intermediate transfer member has a surface layer having good releasability. 1 1. The liquid developer has an insulating liquid having a viscosity of 0.5. ~ 1 0 0 O m P a · s, electric resistance 1 0 ¹² Ω cm or more, surface tension is 2 1 dyn X cm or less, wherein the boiling point is characterized and this Ru der 1 0 0 ° C or higher The image forming method according to any one of Items 1 to 10.  12. The image forming method according to claim 11, wherein the liquid developer uses silicone oil as an insulating liquid.  13. The image forming apparatus according to claim 1, wherein the liquid developer contains a toner having an average particle diameter of 0.1 to 5 zm at a concentration of 5 to 40%. Method. 14. The pre-© We Tsu DOO solution viscosity 0. 5~ 5 m P a · s, electric resistance 1 0 ¹² Ω cm or more, a boiling point of 1 0 0 ~ 2 5 0 ° C, a surface tension of 2 14. The image forming method according to claim 1, wherein the value is 1 dyn / cm or less.  15. The image forming method according to claim 14, wherein the pre-plating liquid contains silicone oil as a main component.  16. The electrostatic latent image formed on the image support is developed with toner, which is charged visualized particles, and the toner image formed on the image support is transferred to a recording medium. Liquid developing device, A high-viscosity liquid developer of 100 to 100 mPa, s in which toner is dispersed at a high concentration in an insulating liquid is used as a developer. Developing means for supplying a latent image surface of the image support by a support to form a toner image on the image support;  Primary transfer means for transferring the toner image formed on the image support onto an intermediate transfer member,  Secondary transfer means for transferring a toner image transferred onto the intermediate transfer member to the recording medium with a recording medium interposed between the secondary transfer member and the intermediate transfer member,  An image forming apparatus, wherein at least one of the image support and the intermediate transfer member is formed of a flexible member.  17. It is preferable that the image support further include a preset unit for applying a splitting solution, which is a dielectric liquid having releasability and being chemically inactive. The image forming apparatus according to claim 16, wherein:  1 8. The secondary transfer means, by heating the secondary transfer body, secondary-transfers the toner image primary-transferred onto the intermediate transfer body onto the recording medium at the same time as fixing. The image forming apparatus according to claim 16 or 17, wherein the image forming apparatus is configured to perform the following.  18. The image forming apparatus according to claim 16, wherein the intermediate transfer member is charged and transfers a toner image by electrostatic force. 20. The image forming apparatus according to claim 16, wherein the intermediate transfer member has an adhesive layer on a surface in contact with the image support. 21. The image forming apparatus according to claim 20, wherein said adhesive layer is formed of fluorosilicone rubber.