JPH02197855A - Color image forming method - Google Patents

Abstract

PURPOSE:To eliminate the need for a transfer drum, to miniaturize a device, and to reduce a cost by constituting a device in such a way that recording paper is fed in synchronization with the leading edge of each toner image, in a method for sequentially transferring and fixing each toner image, formed on a transfer film, on the same recording paper. CONSTITUTION:In a transfer and fixing process, the paper is fed from a paper feeding cassette in synchronization with the leading edge of the image of the transfer film 14 on which a yellow toner 18 is developed; the yellow toner 18 attached to the transfer film 14 is heated and melted by a heat roller 12 and transferred and fixed by a pressure roller 13. When a full toner image, from its leading edge to trailing edge, formed with yellow toner 18 is transferred and fixed, a solenoid 32 is excited. As the result, the pressure roller 13 is rotated in a direction opposite to a direction used at the time of transfer and fixing, and returned to the leading edge of the recording paper 27 in preparation for transfer and fixing for a subsequent color toner image. In such a manner, the images of magenta and cyanogen are sequentially transferred and fixed on the same recording paper 27.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of forming color images using an electrophotographic recording method.

(Prior Art) Conventionally, when forming a color image using an electrophotographic recording method, 44 photoreceptor drums and a transfer drum on which recording paper is supported are both rotated multiple times to transfer the image on the photoreceptor drum. The image is transferred onto the recording paper on the circumference of the drum multiple times in layers.

A schematic diagram of a color electrophotographic copying machine in which the above conventional color image forming method is adopted is shown in FIG.
Publication No. 467; Journal of the Society of Electrostatics, Vol. 9, No. 4, P, 2
53-61.1985).

In the figure, the surface of a photoreceptor drum l rotating at a constant speed in a counterclockwise direction is charged to a predetermined polarity by a corona discharger 2.

When an original image is formed by the exposure optical system 3 on the surface of the photoreceptor that retains an electric charge, the electric charge is dissipated according to the fi of the image area of the original image, and an electrostatic latent image is formed there. The electrostatic latent image is visualized by the developing device 4. In the case of a color copying machine, the developing device t4 includes at least a developing device 5 for yellow development and a developing device W6 for magenta development.
and a developing device 7 for cyan development.

Accordingly, the exposure optical system 3 is equipped with color separation filters for each of pull, green, and red colors. The developing device 24 is provided with a developing device for black development in order to adjust the image tone as necessary.

Development is performed for each color. That is, when a color original image is first projected onto the surface of a photoreceptor using a blue filter, an electrostatic latent image consisting of a yellow component, which is a complementary color to blue, is formed. This is visualized by a developing device 5 for yellow development. The developing device F5 for yellow development contains a developer consisting of yellow toner and iron powder as a carrier, and both are stirred and mixed and charged by W, so that the toner becomes an electrostatic latent image. The charge is reverse electrification. The toner and carrier are attracted together with the developing roller 5a and transported to a developing position close to the photosensitive drum 1.

Next, the green and red color separation filters are selected in the same way, magenta and cyan toner are developed, and the toner images of each color are transferred to the recording paper 9 via the transfer drum 8 to form a color image. It has become.

(Problems to be Solved by the Invention) However, in the conventional color image forming method described above, it is necessary to set the outer circumferential length of the transfer driver 58 to be longer than the recording paper 9.

For example, if the largest recording paper 9 that can be used for recording is 84 size, its longitudinal dimension is 3.
64 tm. In order for this B4 size recording paper 9 to be wrapped around the transfer drum 8 without overlapping,
The outer diameter of the transfer drum 8 must be 1160I11 or more.

Furthermore, if a mechanism for fixing and supporting the recording paper 9 at a fixed position around the transfer drum 8 is included, the transfer drum 8 will be considerably large in size, and the color copying machine will become large.

Furthermore, the mechanism for mounting the recording paper 9 on the transfer drum 8, forming a recorded image, and releasing it is complicated, which increases costs and increases the frequency of jams.

The present invention solves the above-mentioned problems and transfers and fixes the developed toner image onto the recording paper using thermal energy, thereby pressing a roll against the surface of the recording paper onto which the toner image has been transferred. It is an object of the present invention to provide a color image forming method that makes it possible to easily transport a recording paper back and forth after transfer and fixing, and to reduce jams of the recording paper.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a charging step for charging a photoreceptor drum, an exposure step for exposing the photoreceptor drum, and a part of the photoreceptor drum that is in close contact with the photoreceptor drum. The development process consists of a developing process in which toner is attached to a moving transfer film to form a toner image, and a transfer/fixing process in which the toner image on the transfer film is transferred and fixed onto recording paper.

Then, a charging process, an exposure process, and a developing process are performed on the toners of a plurality of colors to form a toner image on the transfer film.

The toner images formed on the transfer film are sequentially transferred and fixed onto the same recording paper, and the recording paper is fed in synchronization with the starting edge of each toner image.

In the transfer/fixing process described above, the transfer film and the recording paper may be moved between two rolls that take two positions, pressure contact and release. In that case, during pressure contact, the toner image on the transfer film is transferred to the recording paper. When the recording paper is released, the recording paper is returned to the starting edge, and the toner images of each color are transferred and fixed onto the recording paper.

Further, the toner is a heat fixing toner or a pressure fixing toner.

Further, in the exposure step, a transfer film that is transparent to the wavelength of the light source may be used, and the exposure may be performed from above the transfer film that moves closely to the photoreceptor drum.

(Function) According to the present invention, the charging process for toners of a plurality of colors,
A toner image is formed on the transfer film by performing the exposure process and the development process, and each toner image is sequentially transferred and fixed onto the same recording paper, and at that time, the recording paper is synchronized with the starting edge of each toner image. Since the paper is fed repeatedly, a color image can be easily obtained by repeating each of the above steps.

Furthermore, since the transfer and fixing are performed simultaneously, it is possible to press the roll against the surface of the recording paper onto which the toner image has been transferred, and the recording paper can be easily transported back and forth after the transfer and fixation.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a conceptual diagram of the color image forming method of the present invention.

In the figure, reference numeral 11 denotes a photoreceptor drum such as a selenium photoreceptor, a negatively charged organic photoreceptor, a positively charged organic photoreceptor, etc., which has a photosensitive layer on a conductive support.

12 is a heating roll, 13 is a pressure roll, and a transfer film 14 is placed between the photosensitive drum 11 and the heating roll 12. The heating roll 12 is made of a metal hollow member with a built-in halogen lamp, or a metal surface with a heating element, and the pressure roll 13 has a silicone surface to ensure heat resistance. It is made of rubber, and the transfer film 14 is pressed against or released from the heating roll 12 via a pressure means and a pressure release means (not shown). The pressure roll 13 is configured to form a nip width as large as necessary for the fixing process during pressure contact.

Further, 15 is a corona discharger as a charging means, and is provided facing the photosensitive drum 11. In addition to this, a brush charger or the like can be used as the charging means.

Reference numeral 16 denotes an exposure device, which is disposed opposite to the transfer film 14 that moves closely to the photoreceptor drum 11, and forms an electrostatic latent image on the photoreceptor drum 11.

As the exposure device 16, any combination of a light source such as a laser or an LEII array and an imaging optical system, or an optical system commonly used in copying machines can be used.

17, 19.21 are developing devices for yellow (Y), magenta (M) and cyan (C), respectively. Each developing device 17, 19, 21 is provided facing the transfer film 14 that moves in close contact with the photoreceptor drum 11.

Then, developer carriers 17a, t9a, 2, respectively.
1a, and the developer carriers 17a, 19a,
Yellow (Y), magenta (M), and cyan (C) toners 18, 20, and 22 are attracted onto the toner 21a and conveyed to develop an electrostatic latent image. As the developing device, any one of a two-component magnetic brush developing device, a -component magnetic brush developing device, a -component non-magnetic developing device, etc. is used. be able to.

Further, on the heating roll 12, a fixing cleaner 23 is provided so as to be in pressure contact with the transfer film 14, and a static elimination brush 24 is provided so as to be in contact with the transfer film 14. Furthermore, a static elimination lamp 2 is provided so as to face the portion of the photosensitive drum 11 immediately after being separated from the transfer film 14 after development.
5 is a provision.

On the other hand, pinch rolls 26a and 26b are disposed on the pressure roll 13, sandwiching the pressure contact portion with the heating roll 12, and are brought into pressure contact with the pressure roll 13 by means not shown.

The recording paper 27 is fed while being wound around the pressure roll 13 as shown in the figure.

Next, FIGS. 2 and 3 show state diagrams of the transfer/fixing section.

FIG. 2 is a diagram showing the state during transfer and fixing, and FIG. 3 is a diagram showing the state when the recording paper is returned.

In the figure, a frame 28 that supports the heating roll 12 and a frame 29 that supports the pressure roll 13 are rotatably supported at a fulcrum 30. The pressure roll 13 is brought into pressure contact with the heating roll 12 by the elastic force of the spring 31 disposed between the frames 28 and 29.

Note that 32 is a solenoid, and the operation of the solenoid 32 causes the movable shaft 33 to reciprocate, and the frame 29 connected to the movable shaft 33 rotates to press and release the pressure roll 13. .

Next, the operation of the color image forming method having the above configuration will be explained.

The photosensitive drum 11 and the pressure roll 12 are rotated at a constant circumferential speed in the direction of the arrow shown in the drawing by a driving means (not shown). As a result, the transfer film 14 is transferred to the photoreceptor drum 1.
1 and the heat generating roll 12, it is moved in the direction of the arrow shown in the figure.

The image forming process will be explained using FIGS. 4 to 6.

FIG. 4 is a diagram showing the image forming process of yellow toner.
Figure 4(a) is a diagram showing the first charging process, Figure 4(b)
) is a diagram showing the first exposure process, FIG. 4(c) is a diagram showing the developing process, and FIG. 4(d) is a diagram showing the transfer/fixing process. Further, FIG. 5 is a diagram showing the magenta toner image forming process, FIG. 5(a) is a diagram showing the second charging process, FIG. 5(b) is a diagram showing the second n-light process, and FIG. c) is a diagram showing the development process, Figure 5(d)
FIG. 2 is a diagram showing a transfer/fixing process. In addition, FIG. 6 is a diagram showing the image forming process of cyan toner, and FIG.
) shows the third charging process, FIG. 6(b) shows the third exposure process, FIG. 6(c) shows the developing process, and FIG. 6(d) shows the transfer/fixing process. FIG.

In the first charging process shown in FIG. 4(a), the surface of the photosensitive drum 11 is directly and uniformly charged by the corona discharger 15. The figure shows an example in which a selenium-based photoreceptor is used, and when a high voltage is applied to the corona discharger 15, the surface is charged with positive polarity.

Between the above charging process and the subsequent exposure process, the transfer film 14 is brought into close contact with the surface of the photoreceptor drum 11.

In the subsequent 1n-th light process shown in FIG. 4(b), the exposure device 16 irradiates the photosensitive drum 11 with light corresponding to the yellow image signal to form an electrostatic latent image.

Subsequently, in the developing process shown in FIG. 4(C), lines of electric force are generated between the developer carrier 17a and the transfer film 14 due to the electrostatic latent image formed on the photoreceptor drum 11. and penetrate the transfer film 14. Therefore, the yellow toner 18 charged on the developer carrier 17a adheres to the transfer film 14.

After the above process, the toner image formed on the transfer film 14 is transferred to the transfer film 14 by a weak electrostatic force.
It is attached to.

Next, in the transfer/fixing process shown in FIG. 4(d),
In synchronization with the starting edge of the image on the transfer film 14 on which the yellow toner 18 has been developed, the recording paper 27 is fed from a paper feed cassette (not shown) and conveyed to the pinch roll 26.
a, 26b and is wound around the pressure roll 13. During transfer and fixing in FIG. 2, the solenoid 32 is de-energized, and the pressure roll 13 is brought into pressure contact with the heating roll 12 by the tension of the spring 31, thereby sandwiching the transfer film 14 and the recording paper 27.

At this time, the yellow toner 18 adhering to the transfer film 14 is heated and melted by the heating roll I2. Then, the molten yellow toner 18 penetrates between the fibers of the recording paper 27 under pressure and is transferred and fixed.

When the toner image formed by the yellow toner 18 is transferred and fixed to the end of the image, the solenoid 32 is energized (
(FIG. 3), as a result, the movable shaft 33 is attracted, the frame 29 rotates about the fulcrum 30, and the pressure roll 13 is released from the heating roll 12. Subsequently, the pressure roll 13 is rotated in the opposite direction to that during transfer and fixing, and returned to the starting edge of the recording paper 27 in preparation for transferring and fixing the toner image of the next color.

Note that a small amount of yellow toner 18 may remain on the transfer film 14 after the transfer to the recording paper 27 is completed, but this is removed by the fixing cleaner 2 on the heating roll 12.
It can be wiped off by pressing 3.

Further, a static eliminating brush 24 for removing static electricity on the transfer film 14 is provided so as to come into contact with the transfer film 14. In this way, the transfer film 14 is cleaned,
Static electricity is removed and it can be used repeatedly.

On the other hand, when the development process is completed, the photoreceptor drum 1
1 separates from the transfer film 14 and is irradiated by a discharge lamp 25 provided facing the photoconductor drum 11 to eliminate residual static charge on the photoconductor drum 11, and returns to the charging process to be used repeatedly.

When the transfer and fixing of the yellow toner 18 is completed as described above, the second charging process (
FIG. 5(a)), the second n-light process performed in response to the magenta image signal (FIG. 5(b)), the development process (
Through the transfer and fixing processes shown in FIG. 5(C)) and FIG. 5(d), a toner image of magenta toner 20 is developed on the recording paper 27 to which the toner image of yellow toner 18 has been transferred and fixed.

After the toner images of the yellow toner 18 and the magenta toner 20 are transferred and fixed, the third charging process (FIG. 6(a)) and the third n light process (
Recording paper on which toner images of yellow toner 1B and magenta toner 20 have been formed through the development process (FIG. 6(C)) and transfer/fixing process (FIG. 6(d)) The toner image of the cyan toner 22 is transferred and fixed onto the toner 27 to form a color image.

Note that yellow toner 18. In addition to the magenta toner 22 and the cyan toner 22, a black toner may be used if necessary.

By the way, the transfer film 14 is heated to 160'C by the heating roll 13 in the transfer/fixing process.
The temperature rises to around. Therefore, it is necessary to have heat resistance, as well as a certain degree of insulation and transparency to the emission wavelength in the exposure process. Considering these, it is desirable to use a film made of a material such as polyester, polyimide, polyetherimide, polyether sulfone, or polyether ether ketone.

In the above embodiments, a polyimide film coated with Teflon is used in consideration of the transfer rate during transfer and fixing. As a result, the transfer rate is approximately 100%,
The burden on the fixing cleaner 23 is reduced, and its lifespan can be extended. Further, the thickness of the transfer film 14 is desirably 200 .mu.m or less in consideration of electric lines of force generated during development, and desirably 10 .mu.m or more in consideration of tensile strength and ease of handling.

Furthermore, in the above embodiments, a case has been described in which a heat fixing toner is used, but a pressure fixing toner such as a microcapsule toner that can be fixed with a minute pressure can be used.

In addition, in the exposure process, a transfer film that is transparent to the wavelength of the light source is used, and the exposure is performed from above the transfer film that moves closely to the photoreceptor drum, but the photoreceptor drum is directly exposed. After performing this, the transfer film may be brought into close contact with the photoreceptor drum before the development process. In this case, the transfer film does not need to have a property of being transparent to the wavelength of the light source. .

Note that the present invention is not limited to the above embodiments,
Various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

(Effects of the Invention) As described above in detail, according to the image forming method of the present invention, a toner image is formed on a transfer film by performing each of the charging step, exposure step, and development step for toners of a plurality of colors. Each toner image is sequentially transferred and fixed onto the same recording paper, and the recording paper is fed in synchronization with the starting edge of each toner image, so the following effects can be achieved. can be played.

(1) Since transfer and fixing are performed simultaneously, it is possible to press the roll against the surface of the recording paper onto which the toner image has been transferred, and it is possible to transport the recording paper back and forth after transfer and fixation with a simple mechanism. become able to.

Therefore, not only can the apparatus be downsized and costs can be reduced, but also the recording paper can be easily conveyed, so that the frequency of occurrence of jams can be reduced.

(2) Since the cleaning process for powder toner remaining on the photosensitive drum can be omitted, the device can be further downsized and costs can be reduced.

(3) Since the cleaning process can be eliminated, toner scattering inside and outside the device can be reduced.

(4) Since it is no longer necessary to dispose of toner after cleaning, contamination of the operator's body and clothes with toner can be removed and maintenance work can be reduced.

(5) Conventionally, contact NW on the photoreceptor drum in the developing process and cleaning process! This increases the lifespan of the photoreceptor drum.

(6) Image disturbances associated with conventional electrostatic transfer processes can be prevented.

(7) It also becomes possible to transfer onto rough paper surfaces such as bond paper, which was difficult in conventional electrostatic transfer processes.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of the color image forming method of the present invention, Fig. 2 is a state diagram during transfer and fixing, Fig. 3 is a state diagram when the recording paper is returned, and Fig. 4 is a diagram showing the yellow toner image forming process. 4(a) is a diagram showing the first charging process, FIG. 4(b) is a diagram showing the 18th light process, FIG. 4(c) is a diagram showing the developing process, and FIG. d) is a diagram showing the transfer/fixing process, FIG. 5 is a diagram showing the magenta toner image forming process, FIG. 5(a) is a diagram showing the second charging process, and FIG. 5(b) is a diagram showing the second exposure. Figure 5 shows the process (
c) is a diagram showing the development process, FIG. 5(d) is a diagram showing the transfer/fixing process, FIG. 6 is a diagram showing the cyan toner image forming process, and FIG. 6(a) is a diagram showing the third charging process. 6(b) is a diagram showing the third exposure process, FIG. 6(c) is a diagram showing the developing process, FIG. 6(d) is a diagram showing the transfer/fixing process, and FIG. 7 is a diagram showing the third exposure process. 1 is a schematic diagram of a color electrophotographic copying machine that employs a conventional color image forming method. 1.11... Photosensitive drum, 2.15... Corona discharger, 4, 5. 6. 7.1? , 19.21...
-Developing device, 9.27... Recording paper, 12... Heat generating roll, 13... Pressure roll, 14... Transfer film, 18... Yellow toner, 20... Magenta toner, 22 ... Cyan Toner Patent Applicant Oki Electric Industry Co., Ltd. Agent Patent Attorney Kawai 1 (1 other person) The present invention exists. 1st generation 1st drum record 1 zone time state diagram Figure 3 Figure 5 Figure 6 The conventional method of forming a color frame is the feather harvesting:! False color electrophotographic copy, Isono's Hakushou EZ Figure 7

Claims (5)

[Claims] (1) (a) A charging step of charging the photoreceptor drum, and (
b) an exposure step of exposing the photoreceptor drum; (c) a development step of forming a toner image by depositing toner on a transfer film that partially moves in close contact with the photoreceptor drum; and (d) a transfer film. It consists of a transfer/fixing process in which the above toner image is transferred to recording paper and fixed, and (e) toner images of multiple colors are subjected to the charging process, exposure process, and development process to form a toner image on the transfer film. (f) sequentially transferring and fixing each of the above toner images onto the same recording paper, and (c) the recording paper being fed in synchronization with the starting edge of each toner image. Method. (2) In the above transfer/fixing process, the transfer film and recording paper move between two rolls that take two positions, pressure contact and release, and at the time of pressure contact, the toner image on the transfer film is transferred and fixed to the recording paper. 2. The color image forming method according to claim 1, wherein the recording paper is returned to the starting edge upon release, and the toner images of each color are transferred and fixed onto the recording paper. (3) The color image forming method according to claim 1 or 2, wherein the toner is a heat fixing toner. (4) The color image forming method according to claim 1 or 2, wherein the toner is a pressure fixing toner. (5) In the exposure step, a transfer film that is transparent to the wavelength of the light source is used, and the exposure is carried out from above the transfer film that moves in close contact with the photoreceptor drum.
The color image forming method according to any one of the above.