JP3020217B2 - Wet development type multicolor image forming method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet development type multicolor image forming method employed in a color electrophotographic copying machine, a printer and the like.

[Conventional technology]

Examples of this type of wet development type multicolor image forming method include:
The latent image on the image carrier is formed into a toner image by wet development using a developing solution composed of a liquid carrier and a toner, and the toner image is transferred onto the intermediate transfer body by repeating a plurality of times. A method is known in which a toner image is superimposed on a sheet, and then the toner image is transferred to transfer paper to obtain a multicolor image. If the amount of the liquid carrier adhering to the intermediate transfer body together with the toner image already transferred is excessive, the color becomes dirty because the toner image is transferred to the intermediate transfer body and then mixed with the superimposed toner image. Each time the toner image is transferred, the process of removing most of the liquid carrier from the intermediate transfer body after the transfer of the toner image to form an image consisting only of the toner particles is repeated. After transfer of the liquid carrier, most of the liquid carrier is removed from the intermediate transfer body, and then, before transferring the superimposed toner image on the intermediate transfer body to the transfer paper, the liquid carrier is supplied to the intermediate transfer body to perform superposition. The separated toner image is easily separated from the intermediate transfer member (see, for example, JP-A-62-289876).

[Problems to be solved by the invention]

However, according to the above configuration, the liquid carrier is supplied to the intermediate transfer body before the superimposed toner image on the intermediate transfer body is transferred to the transfer paper, so that a liquid carrier supply unit for that is required. There was a problem of coming.

The present invention has been made in view of the above-mentioned problems of the related art, and an object of the present invention is to provide a toner image transferred and superimposed on an intermediate transfer member, in which the color becomes dirty or an image becomes unclear. A wet development type multicolor image that can transfer the superimposed toner image on the intermediate transfer member to a transfer paper without blurring and without using a liquid carrier supply unit for the intermediate transfer member. It is to provide a forming method.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a multicolor toner image formed on an intermediate transfer member by repeating transfer of a toner image formed on an image carrier by wet development onto the intermediate transfer member a plurality of times. Is formed, a multi-color image forming method of a wet development method of transferring the multi-color toner image to transfer paper,
Except for the final transfer of the toner image to the intermediate transfer body, after transferring the toner image to the intermediate transfer body, most of the liquid carrier on the intermediate transfer body is removed. is there.

[Action]

According to the present invention having the above-described structure, the latent image on the image carrier is formed into a toner image by wet development using a developing solution including a liquid carrier and a toner, and the toner image is transferred onto the intermediate transfer member. Removing the majority of the liquid carrier from the intermediate transfer body, thereby forming an image consisting only of toner particles on the intermediate transfer body during the final transfer of the toner image from the image carrier to the intermediate transfer body. Repeated before, and then the final transfer of the toner image from the image carrier to the intermediate transfer body was performed, after which the liquid carrier was not removed from the intermediate transfer body, and thus the superimposed on the intermediate transfer body In a state where the toner image is easily separated from the intermediate transfer member, the toner image acts so as to transfer the superimposed toner image to transfer paper.

〔Example〕

One embodiment in which the present invention is applied to a color copying machine which is a multicolor image forming apparatus will be described with reference to FIG.

 FIG. 1 is a schematic configuration diagram of a color copying machine.

First, the drum 1 rotates the photoreceptor surface 11 clockwise and passes through the charging station A. At the charging station A, the corona discharger 2 charges the surface of the photoconductor 11 to a relatively high uniform potential.

After the surface of the photoconductor 11 is charged to a substantially uniform potential, the drum 1 rotates the charged portion of the surface of the photoconductor 11 to the exposure station B. At the exposure station B, a light image of the document is projected onto a charged portion of the surface of the photoconductor 11. At the exposure station B, an exposure device including a document illumination lamp (not shown) and a movable lens device 3 is installed. The original 31 is placed on a flat original placing table 32 with its face down. The document illumination lamp scans the document 31 while moving in synchronization with the movable lens device 3, and reflected light from the document 31 is projected on the surface of the photoconductor 11 through the filter mechanism 33. The monochromatic light image thus formed irradiates the charged portion of the surface of the photoconductor 11 and selectively discharges the electric charge. As a result, an electrostatic latent image corresponding to the monochromatic color of the document 31 is recorded. You. The electrostatic latent image may be recorded by using a laser device or an ion graphic device instead of the above exposure device.

After the exposure, the drum 1 rotates the monochromatic electrostatic latent image recorded on the surface of the photoconductor 11 to the developing station C. The developing station C is provided with three individual developing units 41, 42, 43. Each of the developing units 41, 42, and 43 includes a developing roller configured to carry the liquid developer and make contact with the electrostatic latent image recorded on the surface of the photoconductor 11. The developer includes a liquid carrier such as Isopar (trade name) and toner particles dispersed in the liquid carrier.
Usually, the toner particles are preferably made of a dyed resin. The basic difference between the developing units 41, 42, 43 is that toner particles of different colors are contained therein. For example, the developing unit 41 contains yellow toner particles, the developing unit 42 contains magenta toner particles, and the developing unit 43 contains cyan toner particles. Each of the developing units 41, 42, and 43 operates sequentially to attach a developer containing toner particles having a color complementary to the color-separated light image to the electrostatic latent image. That is, the electrostatic latent image formed from the light image having passed through the green filter is developed with a developer containing magenta toner particles, and similarly, the electrostatic latent image formed from the blue and red light images is Yellow toner particles,
It is developed with a developer containing cyan toner particles. In the color copying machine of the present embodiment, the above three developing units 41, 4
In addition to 2,43, a developing unit 44 containing a developer containing black toner particles is also provided for making a black and white copy. The developed electrostatic latent image is carried to the transfer station D by the drum 1.

In the transfer station D, the toner image is transferred together with the liquid carrier to the intermediate belt 5 which is an intermediate transfer member by the action of static electricity. The intermediate belt 5 is formed of a porous material and is stretched around spaced rollers 51, 52, 53, 54. The intermediate belt 5 rotates in synchronization with the drum 1 and the exposure device so that a plurality of toner images are transferred to the same area of the intermediate belt 5. in this way,
A plurality of toner images can be transferred to the intermediate belt 5 in a state where they are superimposed and aligned. In order to attract the plurality of toner images to the intermediate belt 5 in an overlapping state, the corona discharger 55 scatters ions on the back surface of the intermediate belt 5. Alternatively, an electrically biased roller can be placed adjacent behind the intermediate belt 5 to attract the developed image to the belt. Intermediate belt 5
Rotates counterclockwise and passes around rollers 51,52,53,54. Roller 52 is porous and vacuum device
Connected to 56. When the toner image on the intermediate belt 5 passes over the roller 52, the liquid carrier is sucked from the image area, the solid / liquid ratio of the toner image increases, and the toner particles are attracted to the surface of the intermediate belt 5. Then, since a part of the toner image is buried in the surface of the intermediate belt 5, the next toner image is transferred onto the transferred toner image in an aligned state without disturbing the transferred toner image on the intermediate belt 5. Can be done. When the first toner image on the intermediate belt 5 returns to the transfer station D, the corona discharger 55
The next developed toner image is superimposed on the first toner image from the surface of the photoreceptor 11 to the intermediate belt 5 and attracted in an aligned state. When the first toner image transferred with the second toner image superimposed and aligned again passes over the roller 52, the applied vacuum is applied to the liquid carrier which has been transferred to the intermediate belt together with the second toner image. At the same time, the toner particles of the second toner image are attracted to the surface of the intermediate belt 5, and a part thereof is buried in the intermediate belt 5. When the first toner image transferred in the state where the second toner images on the intermediate belt 5 are superimposed and aligned returns to the transfer station D again, the corona discharger 55 scatters ions on the back surface of the intermediate belt 5 and finally Of the developed third toner image (when a full-color image is obtained by three-color superposition) is superimposed on the first toner image as a final transfer of the toner image from the surface of the photoconductor 11 to the intermediate belt 5. Attract in a consistent state. When the first toner image on the intermediate belt 5 in the state where the second and third toner images are superimposed and aligned passes over the roller 52 again, the operation of the vacuum device 56 is stopped and the third toner image is stopped. The first and second toner images are moistened by the liquid carrier transferred together with the toner images, so that the first and second toner images are easily separated from the intermediate belt 5.

In the final transfer station E, the corona discharger 7 scatters ions on the back surface of the transfer paper 6 sent from a paper feeding device (not shown) to transfer the toner particles of the overlapped toner image to the transfer paper 6. After the toner particles of the overlapped toner image have been transferred from the intermediate belt 5 to the transfer paper 6, the intermediate belt 5 carries the liquid carrier to the transfer station D again. At this point, the polarity of the power source that excites the corona discharger 55 is reversed, and ions of the opposite polarity are scattered from the corona discharger 55 onto the back surface of the intermediate belt 5 and remain on the intermediate belt 5. The toner particles are repelled from the intermediate belt 5 to the surface of the photoconductor 11 of the drum 1 via the liquid carrier, and the liquid carrier is also attached to the surface of the photoconductor 11. This drum 1
The liquid carrier adhered to the surface of the photoconductor 11
11 The residual toner particles can be easily cleaned from the surface.

The liquid carrier and residual toner particles adhering to the surface of the photoreceptor 11 are removed from the surface of the photoreceptor 11 by a resilient and flexible blade 8 installed at the cleaning station F. In the cleaning device disposed at the cleaning station F, the liquid carrier is supplied to the surface of the photoreceptor 11 by the intermediate belt 5 as described above.
It is not necessary to provide a means for supplying the developing solution to the surface of the photoconductor 11. However, if the supply of the liquid carrier from the intermediate belt 5 to the surface of the photoconductor 11 is insufficient for cleaning, a cleaning station is required. A means for supplying a developing solution to the surface of the photoconductor 11 of F may be provided. Thereafter, a voltage is applied to the neutralizing lamp 9 to discharge all residual charges on the surface of the photoconductor 11 in preparation for the next successive image forming cycle.

After the toner particles of the overlapped toner image are transferred to the transfer paper 6 at the final transfer station E, the transfer paper 6 is conveyed to a fixing station (not shown), where the toner particles are transferred to the transfer paper 6 in the form of an image. Permanently settles. Thereafter, the sheet is discharged as a full-color copy on a discharge tray (not shown) outside the apparatus.

In the above embodiment, the intermediate belt 5 as an intermediate transfer member is used.
Has a releasability, the toner particles can be easily separated from the intermediate belt 5 in a state where the liquid carrier is present.
The transfer of the toner particles to the transfer paper 6 at the final transfer station E becomes good, and the toner particles remain on the intermediate belt 5 without being transferred to the transfer paper 6, and the residual toner particles are transferred to the surface of the photoconductor 11 Thus, it is possible to prevent the surface of the photoconductor 11 from being soiled and to mix with the toner particles of the toner image transferred to the intermediate belt 5 to disturb the toner image. As a method of giving the intermediate transfer member a releasability, a release material may be applied to the surface of the intermediate transfer member, or the intermediate transfer member itself may be formed of a release material. For example, the surface of the intermediate belt 5 is coated with a 1% silicone heptane solution and dried to give a releasability of 0.04 g / m ² , or the surface of the intermediate belt 5 is coated with a thermosetting fluorine-based coating agent. The contact angle of the carrier liquid with respect to the surface of the intermediate belt 5 is set to 60 to 90 degrees. X-70, a product name of Shin-Etsu Chemical Co., Ltd.
-029B, 3 parts by weight of a catalyst (trade name: DF-29, manufactured by Shin-Etsu Chemical Co., Ltd.) was added to 100 parts by weight of the catalyst, and FR Thinner or F-113 Freon (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) )
The solution was adjusted to a treatment concentration of 5%, and cured at 100 ° C. for 1 hour to form a coating layer of 1 to 2 μm on the surface of the intermediate transfer member. With a contact angle of 62 degrees and a contact angle of silicon oil of 117 degrees, a very good water and oil repellency was obtained. When the intermediate transfer body itself is formed of a release material, a release porous material, for example, a porous sheet made of ethylene tetrafluoride polymer, a trade name of Polykin paper PA10L manufactured by Daikin Industries, Ltd.
Etc. can be used.

Next, another embodiment of the present invention will be described with reference to FIG.

FIG. 2 is a schematic configuration diagram of the color copying machine of the present embodiment.

The difference between the color copying machine of the present embodiment and the above embodiment is that
The rollers 51 and 54 are arranged near the surface of the photoconductor 11, and the intermediate belt 5 and the surface of the photoconductor 11 are brought into surface contact to increase the contact area. The other points are the same as those in the above embodiment.

According to this embodiment, since the contact area between the surface of the photoconductor 11 and the intermediate belt 5 at the transfer station D is larger than that of the above embodiment, the transfer of the toner image on the surface of the photoconductor 11 to the intermediate belt 5 can be performed. Can be performed well. After the toner particles have been transferred to the transfer paper 6 at the final transfer station E, the intermediate belt 5 to which the liquid carrier has adhered comes into contact with the photoconductor 11 again, and the liquid carrier on the intermediate belt 5 is transferred to the photoconductor 11 side. In this case, since the contact area between the surface of the photoconductor 11 and the intermediate belt 5 is large, more liquid carrier can be adhered to the surface of the photoconductor 11. In particular, when the supply of the developing solution to the surface of the photoconductor 11 by the developing unit is stopped at the end of the full-color development, the final transfer station E
Since the developer is hardly attached to the surface of the photoconductor 11 where the intermediate belt 5 to which the toner particles are transferred to the transfer paper 6 and the liquid carrier is adhered comes into contact with the Applying a large number of liquid carriers is advantageous for cleaning at the cleaning station F.

In each of the above embodiments, the roller 52 disposed on the back surface of the intermediate belt 5 is connected to the vacuum device 56 in order to remove the liquid carrier from the intermediate belt 5 as the intermediate transfer member. In addition, a liquid carrier removing device such as a heating device and a blowing device may be arranged on the surface side of the intermediate belt 5.

When the liquid carrier is removed from the front side of the intermediate belt 5 instead of sucking and removing the liquid carrier from the back side of the intermediate belt 5 via the intermediate belt 5 which is an intermediate transfer member, the intermediate belt is formed of a non-porous material. You may.

Further, the intermediate transfer member is not limited to a belt shape, and may be a roller shape.

〔The invention's effect〕

As described above, according to the present invention, until the final transfer of the toner image from the image carrier to the intermediate transfer body, the toner image is transferred onto the intermediate transfer body, and then the size of the liquid carrier from the intermediate transfer body is increased. By removing the part, an image consisting only of toner particles is formed on the intermediate transfer body, so that the toner image transferred and superimposed on the intermediate transfer body may become dirty or blurred. On the other hand, after the final transfer of the toner image from the image bearing member to the intermediate transfer member, the liquid carrier is not removed from the intermediate transfer member, so that the superimposed toner image on the intermediate transfer member is intermediately transferred. Since it is easy to separate from the transfer member, it is possible to transfer the superimposed toner image on the intermediate transfer member to the transfer member without using a liquid carrier supply unit for the intermediate transfer member. Effect A.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a color copying machine according to one embodiment of the present invention, and FIG. 2 is a schematic configuration diagram of a color copying machine according to another embodiment. 11 photoreceptor, 41, 42, 43, 44 developing unit, 5
Intermediate belt, 56: Vacuum device, 6: Transfer paper

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-62-289876 (JP, A) JP-A-63-264776 (JP, A) JP-A-2-44371 (JP, A)

Claims (2)

(57) [Claims] 1. A method of forming a multicolor toner image on an intermediate transfer member by repeating the transfer of a toner image formed on an image carrier by wet development onto an intermediate transfer member a plurality of times. In a multicolor image forming method of a wet development method of transferring a color toner image to transfer paper, except for the final transfer of the toner image to the intermediate transfer body, after the transfer of the toner image to the intermediate transfer body, A wet development type multicolor image forming method, wherein most of the liquid carrier on the intermediate transfer member is removed. 2. The multicolor image forming method according to claim 1, wherein said image bearing member and said intermediate transfer member are brought into surface contact with each other.