JPH03202882A - image forming device - Google Patents

Abstract

PURPOSE:To improve an image by supplying a developer with a developing roller, transferring an obtained toner image on a recording member, and fixing the image by using a heating roller and a pressure roller. CONSTITUTION:Electrification is applied to a photosensitive drum 1 uniformly with a main charger 2, and an electrostatic latent image is formed at an exposure position 3. Then, the static elimination of an area other than an image forming area with an eraser 4 is performed, and the latent image is developed paper 7 sent with a carrying roller 6 with a transfer charger 8. After that, the transfer paper 7 is separated from the drum 1, and is transferred on a carrying belt 9, and is fixed at a fixing device 10 with the heating roller 31 and the pressure roller 32. Then, heating and pressing are performed simultaneously, which stretches the toner image uniformly. Thereby, it is possible to cover the image with toner when fixing is performed even when a void part occurs, and to obtain a uniform toner image with high density, and to improve the image.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus using a wet developer, such as a copying machine, a facsimile machine, and a printer.

[Prior art]

In a developing device of an image forming apparatus using a liquid developer, an elastic foam base is provided around a rigid central roller such as a developing roller, a squeeze roller, a cleaning roller, etc., and the elastic foam is made of a conductive material. For example, Japanese Patent Application Laid-open No. 1983-1980 discloses the use of a roller covered with a rope.
It is known from the publication No. 111739. This method of developing by bringing the developing roller, which uses an elastic body covered with a rope, into contact with the photoreceptor does not require any other means to remove excess developer from the photoreceptor after development. It has the advantage that it can be made smaller. However, in terms of image formation,
Since the rope of the developing roller is in direct contact with the photoreceptor, the latent image in the area in contact with the rope is not developed, and when transferred, white areas without toner are scattered, resulting in abnormal images. There was a problem in creating.

In order to solve this problem, it is possible to reduce the wire diameter of the rope, but reducing the wire diameter of the rope reduces the durability of the developing roller and reduces the amount of developer that can contribute to development, that is, the wire of the rope. A problem arises in that the developer stored in the space of the door becomes insufficiently supplied, resulting in a decrease in image density.

It is also possible to weaken the contact pressure of the rope against the photoreceptor so that the developer can penetrate into the contact area between the photoreceptor and the rope, but this reduces the effectiveness of removing excess liquid, The advantage of removing excess liquid by a developer roller having an elastomer coated with a rope is reduced.

When a liquid developer is supplied to a photoreceptor by a developing roller, the developing roller is rotated in the developer to supply the developer to the developing roller, as disclosed in JP-A-54-84739 and JP-A-53-111739. This is commonly done as shown in the above publications.

In this type of developing device, the used developing solution is squeezed out and removed by a squeezing roller that is in pressure contact with the developing roller in the developing solution. However, the developing roller is originally designed to supply a small amount of developer for development, and it is necessary to efficiently remove the squeezed out used developer from around the developing roller, which causes problems such as agitation of the developer. This is a very difficult problem.

In this respect, it is more convenient to use the developing roller in the air rather than in the liquid when it comes to removing the used developer, but if the carrier liquid in the developer is not a high-boiling point solvent that is difficult to emit, the toner may dry and stick. This can easily cause trouble. If a high boiling point solvent is used to prevent the toner from drying and fixing, there is a problem in that it cannot be fixed by conventional drying and fixing methods.

[Problem to be solved by the invention]

The present invention solves the above-mentioned problems and maintains the advantages of developing using a developing roller having an elastic body covered with a rope, while also producing good results without causing white spots or toner drying and sticking. An object of the present invention is to provide an image forming apparatus that can obtain images.

[Means to solve the problem]

The present invention solves the above problems by forming an electrostatic latent image on a photoconductor by charging and image exposure, and applying a developer containing a thermally crosslinkable wet toner and a carrier liquid made of a high boiling point solvent to a rotating shaft. A toner image obtained by supplying the electrostatic latent image to the photoreceptor using a developing roller whose periphery is covered with an insulating net portion around an elastic body that is a conductive open-cell member provided on the surface and develops the electrostatic latent image. The problem has been solved by an image forming apparatus characterized in that the image forming apparatus transfers the image to a recording member and fixes the transferred recording member by a fixing device having a heating roller and a pressure roller.

[Effect]

According to the present invention, a developer containing a thermally cross-linked toner and a carrier liquid made of a high-boiling solvent is supplied in the air to a developing roller made of a conductive elastic material that is an open-cell member and its surroundings covered with an insulating net. Then, the developer stored in the web part and the bubble member of the developing roller is brought into pressure contact with the photoreceptor to develop the latent image on the photoreceptor, the developed toner image is transferred to a recording member, and the transferred recording member is heated. It is fixed by heating and applying pressure with a roller.

According to the present invention, since the developer is supplied to the developing roller rotating in the air, the used developer can be efficiently squeezed out by the squeezing roller regardless of the stirring of the developer. Since a boiling point solvent is used, it is possible to prevent the toner from drying and sticking.Furthermore, since the recording material is directly heated and pressurized using a heated roller, it can be reliably fixed even with a developer using a high boiling point solvent as the carrier liquid. . At this time, even if white areas without toner occur due to the wire portions in the transferred image, the heated roller melts and spreads the toner, so that the white areas are also covered with toner and a toner image of uniform density is obtained. Furthermore, since a toner made of a thermally crosslinkable resin is used as the developer toner, even if the toner is melted by the heating roller, the toner is prevented from being offset to the heating roller.

〔Example〕

The details of the present invention will be explained based on embodiments shown in the drawings.

The wet-type electrophotographic copying machine shown in FIG. 1 has a photoreceptor drum 1 that is rotated at a constant speed in the direction of the arrow, and the photoreceptor drum 1 is uniformly charged by 2 during main charging.
At an exposure value of 13, an exposure device projects a development pattern to form an electrostatic latent image, an eraser 4 removes static electricity outside the image forming area, a wet development device 5 develops the latent image, and a sheet feeder (not shown) It is transferred to the transfer paper 7 that is left behind and is sent by the conveyance roller 6 by the transfer charging medium 8, and the transfer paper is transferred to the photoreceptor l.
The toner is separated and conveyed by a conveyor belt 9, fixed by a fixing device 10, and discharged, and then transferred to a photosensitive drum l.
The residual toner is removed by the cleaning device 11,
The residual potential is energized by the static eliminating lamp or the static eliminating charge 12 to eliminate the residual potential.

The developing device 5 includes a developing roller 13 and a squeezing roller 14 that is movable between a contact position with the developing roller 13 and a position away from the developing roller 13. The developing roller 13 is brought into pressure contact with the photoreceptor drum 1, and at the contact portion, the photoreceptor drum 1 and the developing roller 13 are rotated in the direction of the arrow at a synchronous speed in the same direction. A supply nozzle 16 serving as a liquid supply section for supplying a developer is disposed in the developer container 15 having the developer roller 13 , and the developer is supplied into the developer container 15 . Supply nozzle 16
A developer is supplied from a developer tank 19 through a conduit 17 by a supply device 18 such as a pump.

As shown in FIG. 2, the developing roller I3 has a conductive elastic body 21 formed in a cylindrical shape around a core metal 20, and the periphery of the elastic body 21 is covered with an insulating net portion 22. The elastic body 21 is formed as an open cell member, and the rope portion 22 is formed of a wire rod having a wire diameter of 50 to 150 μm so that the aperture ratio is 50% or more.

In the developing bag W15, in order to prevent the developing roller 13 from being deformed, the developing roller 13 is moved so as not to come into pressure contact with both the photoreceptor l and the aperture roller 14 except during the copying operation.
Advantageously, the positions of the squeeze rollers 14 are moved so that they are brought into pressure contact with each other during the copying operation.

A developer is supplied from the supply nozzle 16 while the developing roller 13 is in pressure contact with the photoreceptor l and the aperture roller 14. Transport to 1. At that time, developing roller 1
The amount of the developer above 3 is regulated to the necessary minimum by the blade 23, and at the same time it is made uniform. The developer remaining on the photoreceptor 1 after development has a reduced toner concentration and cannot be used as it is for the next development, so it is squeezed out by the squeezing roller 14. The developer squeezed out from the developer roller 13 is collected from the developer container 15 into the developer tank 19 by a collection vibrator 24, and the toner concentration is adjusted and then supplied to the developer container 15 by the supply device 18 again. A developing bias voltage is applied to the developing roller 13 in order to prevent background stains on copies.

During development on the photoreceptor 1, the developer is pushed out by the volume change in the portion of the developing roller 13 that is in pressure contact, and a liquid pool is formed on the rear side in the rotational direction, and the developer in the pool and the developing roller 13 are pushed out. Development is performed using the developer in the portion that is in contact with the photoreceptor 1. On the front side in the rotational direction of the developing roller 13, the deformed portion of the developing roller 13 returns to its original state, so the developer is sucked up by the volume change at that time, and the excess developed developer on the photoreceptor l is transferred to the surface of the photoreceptor. remove from The removed developer is collected in the developer tank 19.

The transfer paper 7 onto which the developed image of the photoreceptor 1 has been transferred by corona transfer is fixed by a heating roller 31 and a pressure roller 32 in a fixing device 10.

In the fixing device 10, a fixing roller 31 and a pressure roller 32 are arranged so as to be in pressure contact with each other across a paper passing path for the transfer paper 7 carrying unfixed toner.

A cam surface of a pressure cam 34 is pressed against the shaft portion of the pressure roller 32 based on the biasing force of a spring 35, so that a predetermined pressure force is applied to the pressure roller 32. It has become. Further, the outer layer of the pressure roller 32 is formed of a silicone rubber layer, and both of the rollers 31
A predetermined nip width is formed between the transfer paper and the toner 32 to buy time for applying heat to the transfer paper and toner for fixing.

The fixing roller 31 is formed by coating the surface of a hard roller with fluororesin, and inside it,
Heater 33 as a 100v, 750W fixing heat source
is built-in. This heater 33 is equipped with a thermistor 36 and a temperature fuse 37, which are installed outside the fixing roller 32, and the temperature is controlled by these. Further, a fixing claw 38 and a coated felt 39 are arranged on the outer peripheral surface of the fixing roller 31 so as to be in contact therewith.

The transfer paper 7 is fed so that its toner image transfer surface comes into contact with the fixing roller 31 side, so that the toner image transfer surface of the transfer paper is brought into contact with the heater 33 side, which is the fixing heat source. The sides are in direct contact.

The developer in the developing device 5F5 contains the following thermally crosslinkable toner.

First, as resin, ■ 50 parts by weight of ST (styrene), 40 parts by weight of MMA (methyl methacrylate), and 10 parts by weight of DVB (divinylbenzene).
Contains parts by weight: ■ ST (styrene) is 60! If part, containing 35 parts by weight of MA (methyl acrylate), 5 parts by weight of DVB (divinylbenzene), ■ 75 parts by weight of ST (styrene), 20 parts by weight of n-BA, DVS (divinylbenzene) Pigments containing 5 parts by weight are used, while pigments such as Mocal L, Printex v1 Raven #4o1 #30, #
20, Mitsubishi #44, etc. are used.

Using such materials, resin
Kneaded in a normal kneader at a mixing ratio of 80 to 90 parts by weight,
The mixture is kneaded three times with a heated roller (100°C) and coarsely ground with a ball mill, etc. to a powder of 0.1 to 2.
Flushing carbon of 0μ is obtained. When 100 parts by weight of the flushing carbon and 5001 parts by weight of Isoper H as a dispersant are dispersed in a ball mill for 20 hours, a concrete toner with a solid content of 20% having toner particles of 0.3 to 5 μm is produced. is obtained.

In addition to the above lecithin, as the polarity control agent, -C1
A large number of polymers such as vinyl chloride, vinyl chloride, vinyl acetate copolymer, and chlorinated rubber can be employed. The conctners created in this way are Isopar H1 Isopar V
1 silicone oil KFs8 (methyl phenyl diaxane) to form a developer solution. - For example, for 50 g of the above toner, 10 wt% of the carrier liquid as a high boiling point solvent is added to Isopar H.
It is also possible to use a developer solution prepared by mixing Isopar V or silicone oil KF-58 (methyl phenyl siloxane) (manufactured by Shin-Etsu Silicon Co., Ltd.) to a concentration of 11.

Since the developer uses a toner made of thermally crosslinkable 41 resin, there is no offset to the heating roller 31 during heat fixing, and the toner is directly heated and melted by the heating roller 31, and at the same time it is pressed by a pressure roller. As a result, the toner image can be uniformly stretched. Therefore, even if the rope of the developer roller 13 comes into direct contact with the copying process and the toner does not adhere to the white areas, the toner is stretched out and the white areas can also be covered with toner, so that the toner is uniform. A toner image with high density can be obtained.

The residual developer on the photoreceptor drum 1 after the transfer is removed by a cleaning device 11. The cleaning device fll has a cleaning roller 25 and a cleaning blade 26 arranged so as to be in contact with the photoreceptor drum l, and a liquid supply section 2 formed at the upper end of the cleaning container 11a.
a cleaning liquid supply section as 7;
The cleaning liquid supplied from 7 is supplied to a cleaning roller 25, for example, a foam roller. The cleaning roller 25 collects residual toner from the photoreceptor drum 1, and the cleaning liquid containing the collected toner is squeezed by a squeezing roller 28 disposed in contact with the cleaning roller 25, and the liquid receiver formed at the bottom of the cleaning container 11a is squeezed out. It will be collected at 30.

The liquid receiver part 30 has a liquid discharge port, and discharges the collected cleaning liquid to the product tank 19. If the liquid supplied from the liquid supply section 27 is directly supplied to the cleaning roller 25, it will not cover the entire length of the cleaning roller 25, so a liquid diffusion vi29 is provided.

〔effect〕

According to the present invention, since the developer has a toner made of a thermally crosslinkable resin and a high boiling point solvent as a carrier liquid,
Even in fixing using a heating pressure roller, it is possible to prevent the toner from being offset to the heating roller, and therefore the toner can be directly heated and melted.

As a result, the toner image can be uniformly stretched by applying pressure at the same time as heating, and even if there is a white area where toner does not adhere due to contact with the mesh part of the developing roller, it can be covered with toner during fixing. It was possible to obtain a toner image that was uniform and had high density.

Since a high boiling point solvent is mixed as the carrier liquid in the developing solution, it is possible to prevent the dry toner on the developing roller from solidifying, and there is no need to provide a large developing tank to prevent the developing roller from drying. It is now possible to separate the developing tank. This has made it possible to arrange multiple developing units around the photoreceptor drum, and the device layout has become more versatile.

[Brief explanation of drawings]

FIG. 1 is an overall schematic explanatory diagram of an image forming apparatus according to the present invention;
FIG. 2 is a partially cutaway perspective view of the developing roller. ■...Photoconductor 2...Main charging 3.
...Exposure value 15...Developing device 7...Recording member (transfer paper) 8...Transfer charger

Claims (1)

[Claims] (1) An electrostatic latent image is formed on the photoreceptor by charging and image exposure, and a developer containing a thermally crosslinkable wet toner and a carrier liquid made of a high boiling point solvent is applied to the surface of the rotating shaft. The electrostatic latent image is developed by supplying the electrostatic latent image to the photoreceptor using a developing roller whose periphery is covered with an insulating net portion around an elastic body that is an open cell member, and the obtained toner image is transferred to a recording member, An image forming apparatus characterized in that a transferred recording member is fixed by a fixing device having a heating roller and a pressure roller.