JPH0812501B2 - Color image forming method - Google Patents

Description

The present invention relates to a method for forming a color image by an electrophotographic recording method.

(Prior Art) Conventionally, when a color image is formed by using an electrophotographic recording method, the photosensitive drum and the transfer drum supporting the recording paper are both rotated multiple times to transfer the image on the photosensitive drum. It is designed to be transferred multiple times on the recording paper on the drum surface.

FIG. 8 is a schematic diagram of a color electrophotographic copying machine in which a conventional color image forming method is adopted (Japanese Patent Publication No. 63-34467; Journal of Electrostatics, Vol. 9, No. 4, P. 253-61, 1985
reference).

In the figure, the surface of the photosensitive drum 1 which rotates at a constant speed in the counterclockwise direction is charged to a predetermined polarity by the corona discharger 2.

When a document image is formed by the exposure optical system 3 on the surface of the photoconductor drum 1 holding the charge, the charge is dissipated according to the density of the image area of the document 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 4 includes at least a developing device 5 for developing yellow color, a developing device 6 for developing magenta color, and a developing device 7 for developing cyan color. Has been.

In response to this, the exposure optical system 3 is provided with color separation filters for each color of blue, green and red. The developing device 4 is provided with a developing device (not shown) for developing a black color 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 the photoconductor drum 1 using a blue color separation film, an electrostatic latent image corresponding to a yellow component having a complementary color relationship with blue is formed. And
The electrostatic latent image is visualized by the developing device 5 for developing the yellow color. The developing device 5 for developing the yellow color contains a developer consisting of yellow toner and iron powder which is a carrier, and both are agitated (stirred) to be friction-charged. The toner is charged with the opposite polarity to the charge of the electrostatic latent image. The yellow toner and the carrier are attracted to the developing roller 5a and are conveyed to the developing position near the photosensitive drum 1.

Then, similarly, green and red color separation filters are selected to develop magenta and cyan toners, and the toner images of the respective colors are transferred onto the recording paper 9 via the transfer drum 8 to form a color image. It is like this.

(Problems to be Solved by the Invention) However, in the conventional color image forming method, it is necessary to set the outer peripheral length of the transfer drum 8 longer than the recording paper 9.

For example, if the largest recordable recording paper 9 is B4 size, this longitudinal dimension is 36
It is 4 [mm]. In order for the B4 size recording paper 9 to be wound around the transfer drum 8 without overlapping, the outer diameter of the transfer drum 8 must be 116 [mm] or more.

Further, 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 having a considerably large size is required, and the color transfer machine becomes large.

Further, the mechanism from mounting the recording paper 9 on the transfer drum 8 to form a recorded image and releasing the recording image is complicated, resulting in high cost and frequent jam.

The present invention solves the above problems of the conventional color image forming method, eliminates the need for a transfer drum and a mechanism for attaching a recording sheet to the transfer drum, forming a recorded image, and releasing the image. An object of the present invention is to provide a color image forming method capable of reducing jam of recording paper by forming toner images of a plurality of colors on a film.

(Means for Solving the Problems) Therefore, in the color image forming method of the present invention, a charging step of charging the photoconductor drum, and exposing the photoconductor drum corresponding to an image signal of a predetermined color, An exposure step of forming an electrostatic latent image, and an endless transfer film that moves in close contact with the outer periphery of the photosensitive drum at a position facing the photosensitive drum via the transfer film. Further, using any one of a plurality of developing means for developing a plurality of colors arranged at a position facing the close contact position of the photosensitive drum and the transfer film, the photosensitive drum is formed. A developing step of forming a toner image of a predetermined color on the transfer film by adhering a toner of a predetermined color corresponding to the formed electrostatic latent image, and a pair of pressure contact position and release position. Pressure roll The transfer film having the toner images of a plurality of colors formed on the surface thereof is superposed on the recording paper and passed between the pair of rolls to form the toner images of the plurality of colors formed on the transfer film. A transfer / fixing step of transferring and fixing to a recording paper is provided.

Then, prior to the transfer / fixing step, the pair of rolls are placed at a release position, and a series of steps of the charging step, the exposing step and the developing step are repeatedly performed corresponding to each color in advance to obtain the transfer film. Toners of the respective colors are sequentially deposited on the toner images to form a plurality of toner images, and at least the toner images other than the toner image formed last among the toner images of the plurality of colors are formed on the transfer film. Each time a toner image of each color is sequentially formed, it is heated and melted by a heating unit to be fixed on the transfer film, and after the final toner image is formed on the transfer film, the transfer / fixing step is used. The transfer film having the toner images of a plurality of colors on the surface and the recording paper are sandwiched by the pair of rolls placed at the pressure contact position, and passed between the rolls. By, for fixing and transferring the toner images on the recording paper.

(Operation) According to the present invention, as described above, in the color image forming method, the charging step of charging the photoconductor drum, and the exposure of the photoconductor drum in correspondence with the image signal of a predetermined color An exposure step of forming a latent image and a position on the endless transfer film that moves in close contact with the outer periphery of the photosensitive drum, at a position facing the photosensitive drum via the transfer film, and Corresponding to an electrostatic latent image formed on the photoconductor drum by using any one of a plurality of color developing means arranged at a position facing the close contact position of the photoconductor drum and the transfer film. And a toner of a predetermined color is attached to form a toner image of a predetermined color on the transfer film.

Further, a pair of rolls which can take two positions of a pressure contact position and a release position are placed at the pressure contact position, and the transfer film having the toner images of a plurality of colors formed on the surface thereof and the recording paper are overlapped with each other, and the space between the pair of rolls is placed. And a transfer / fixing step of transferring the toner images of a plurality of colors formed on the transfer film onto the recording paper and fixing the toner images.

In this case, the photosensitive drum is charged in the charging step, and the photosensitive drum is exposed in the exposure step in correspondence with the image signal of a predetermined color to form an electrostatic latent image.

Further, the endless transfer film is moved in close contact with the outer periphery of the photoconductor drum partially, at a position facing the photoconductor drum via the transfer film, and
A plurality of developing means for developing a plurality of colors for developing a plurality of colors are arranged at a position facing a position where the photoconductor drum and the transfer film are in close contact with each other. Then, in the developing step, a toner of a predetermined color is adhered onto the transfer film corresponding to the electrostatic latent image formed on the photosensitive drum by using any one of the developing means to form a toner image.

Further, in the transfer / fixing step, the pair of rolls are placed at a pressure contact position, the transfer film having a plurality of color toner images formed on the surface thereof and the recording paper are overlapped and passed between the pair of rolls, The toner images of a plurality of colors formed on the transfer film are transferred and fixed on a recording paper.

Then, prior to the transfer / fixing step, the pair of rolls are placed at the release position, and the series of steps of the charging step, the exposing step and the developing step are repeatedly performed corresponding to each color in advance to obtain the transfer film. Toners of the respective colors are sequentially deposited on the toner images to form a plurality of toner images, and at least the toner images other than the toner image formed last among the toner images of the plurality of colors are formed on the transfer film. Each time a toner image of each color is sequentially formed, it is heated and melted by a heating unit to be fixed on the transfer film and fixed on the transfer film, and after the final toner image is formed on the transfer film, the transfer / transfer While sandwiching the transfer film having a plurality of color toner images on the surface and the recording paper by the pair of rolls placed at the pressure contact position using a fixing step. By passing between the rolls, for fixing and transferring the toner images on the recording paper.

In this case, each color toner is subjected in advance to a charging step, an exposure step and a developing step to sequentially form toner images of each color on the transfer film (however, among the toner images, at least the toner formed last is formed). The toner images other than the images are once (once) heated and melted and fixed on the transfer film), and then all the toner images are transferred and fixed on the recording paper.

Therefore, after all the toner images of a plurality of color toners are formed on the transfer film, they are transferred and fixed on the recording paper, so that each time the toner images of each color are formed. There is no need to feed or feed recording paper.

(Example) Hereinafter, the Example of this invention is described in detail, referring drawings.

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

In the figure, reference numeral 11 denotes a photosensitive drum such as a selenium photosensitive member having a photosensitive layer provided on a conductive support, a negative charging type organic photosensitive member, a positive charging type organic photosensitive member, or the like. Reference numeral 12 is a heating roll, 13 is a pressure roll, and 35 is a rolling roll. An endless transfer film 14 is wound between the photoconductor drum 11, the heating roll 12 and the rolling roll 35. The heat generating roll 12 is composed of a metal hollow member having a halogen lamp built therein, a metal member provided with a heat generating element, or the like. Further, the pressure roll 13 has a surface made of silicone rubber for ensuring heat resistance, and is a transfer film 14 which is supported by the heating roll 12 so as to be conveyable via a pressure means and a pressure release means (not shown). Is pressed against or released. The pressure roll 13 is designed to have a nip width required for the fixing process at the time of pressure contact.

Further, 15 is a corona discharger for charging, which is arranged so as to face the photoconductor drum 11. As charging means,
Besides, a brush charger or the like can be used.

Reference numeral 16 denotes an exposure position, which is disposed so as to face the photoconductor drum 11 and forms an electrostatic latent image on the photoconductor drum 11. As the exposure device 16, a combination of a light source such as a laser or an LED array and an imaging optical system is used.

Reference numerals 17, 19, and 21 denote developing devices for developing yellow (Y), magenta (M), and cyan (C) colors, respectively. Each of the developing devices 17, 19, 21 has a developer carrier 17a, 19a, 21a, respectively, and the developer carrier 17a, 19a, 21a.
Yellow, magenta and cyan toners 18, 20,
22 is adsorbed, conveyed to the developing position, and developed according to the electrostatic latent image. As the developing device, any of a two-component magnetic brush developing device, a one-component magnetic brush developing device, a one-component non-magnetic developing device and the like can be used. Each of the toners 18, 20, 22 used here has a heat fixing property.

Further, a fixing cleaner 23 is provided so as to face the heat generating roll 12 through the transfer film 14 and the pressure contact position and the release position of the transfer film 14 can be selected. It is arranged. Then, a charge eliminating lamp 25 is arranged so as to face the photoconductor drum 11 immediately after being separated from the developed transfer film 14.

On the other hand, the recording paper 27 includes the paper feed cassette 26 and the paper feed roll 12.
8. Paper is fed through a transport system including a paper feed roll 129 and a paper discharge roll 30.

Fig. 2 is a state diagram during color image formation, and Fig. 3 is a transfer and
It is a state diagram at the time of fixing.

In the figure, a frame 28 supporting the heat generating roll 12,
A frame 29 that supports the pressure roll 13 and a fulcrum 30 are rotatably supported. Then, by the elastic force of the spring 31 arranged on each of the frames 28 and 29, the heat generating roll 12
The pressure roll 13 and the fixing cleaner 23 are brought into pressure contact with the transfer film 14 which is supported so as to be conveyed.

Reference numeral 32 is a solenoid, and the movable shaft 33 is reciprocated by the operation of the solenoid 32, and the frame 29 connected to the movable shaft 33 is rotated to press and release the pressure roll 13. .

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

As described above, in the state of forming the color image, the solenoid 32 is excited and the pressure roll 13 is released from the transfer film 14 and the heat roll 12 as shown in FIG. And in this state,
The photoconductor drum 11 (FIG. 1) and the heat-generating roll 12 are rotated at a constant peripheral speed in the direction of the arrow shown by the drive means (not shown). As a result, the transfer film 14 is moved in the direction of the arrow shown in the figure by the frictional force between the photoconductor drum 11 and the heat roller 12. Incidentally, 27 is a recording paper.

The image forming process will be described with reference to FIGS.

FIG. 4 is a diagram showing an image forming process of cyan toner,
FIG. 4 (a) is a diagram showing a first charging process, FIG. 4 (b) is a diagram showing a first exposure process, FIG. 4 (c) is a diagram showing a developing process, and FIG. 4 (d) is a diagram. It is a figure which shows a welding process. Further, FIG. 5 is a diagram showing an image forming process of magenta toner, FIG. 5 (a) is a diagram showing a second charging process, FIG. 5 (b) is a diagram showing a second exposure process, and FIG. FIG. 5C is a diagram showing a developing process, and FIG. 5D is a diagram showing a welding process. 6 is a diagram showing an image forming process of yellow toner, and FIG. 6 (a) is a third diagram.
FIG. 6B is a diagram showing a charging process, FIG. 6B is a diagram showing a third exposure process, FIG. 6C is a diagram showing a developing process, and FIG. 7 is a diagram showing a transfer / fixing process.

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

In the first exposure process of FIG. 4B, the exposure device 16 (FIG. 1) irradiates the photosensitive drum 11 with light corresponding to the cyan image signal to form an electrostatic latent image.

The transfer film 14 is brought into close contact with the surface of the photoconductor drum 11 between the exposure process and the development process.

Subsequently, in the developing process of FIG. 4 (c), the lines of electric force associated with the electrostatic latent image formed on the photoconductor drum 11 are generated between the developer carrying member 21a and the transfer film 14. It occurs through 14. Therefore, the developer carrier 21
The charged cyan toner 22 on a is transferred to the transfer film 14
Adheres to

After the above process, the toner image formed on the transfer film 14 adheres to the transfer film 14 with a weak electrostatic force.

Next, in the fusing process of FIG. 4 (d), when the transfer film 14 on which the toner image of the cyan toner 22 is formed reaches the contact portion with the heat generating roll 12, the heat of the heat generating roll 12 causes the cyan toner The toner 22 is heated and melted. By this heating and melting, the cyan toner 22 is fixed on the transfer film 14 with a force stronger than the electrostatic force.

Thus, the cyan color image forming process is completed. Then, in order to remove the static electricity remaining on the transfer film 14 before moving to the image forming process of the next magenta color, the static elimination brush 24 is arranged so as to contact the transfer film 14, by the static elimination brush 24. The transfer film 14 is neutralized so that it can be used repeatedly.

On the other hand, when the developing process is completed, the photosensitive drum
11 is separated from the transfer film 14 and is irradiated by a static elimination lamp 25 arranged so as to face the photoconductor drum 11, the antistatic charge remaining on the photoconductor drum 11 is neutralized, and the process returns to the charging process again and is repeatedly used. It

As described above, after the toner image of the cyan toner 22 is melted by heating, as shown in FIG. 5, the second charging process (FIG. 5A) is performed, and the second charging process is performed in response to the magenta image signal. The toner image of magenta toner 20 is developed on the transfer film 14 on which the toner image of cyan toner 22 has been formed through the exposure process (FIG. 5 (b)) and the development process (FIG. 5 (c)). To be done. Here, the cyan toner 22
Is adhered onto the transfer film 14, so that it does not enter the developing device 19.

Next, in the welding process of FIG. 5D, the toner image of the cyan toner 22 is heated and melted as described above,
Further, when the transfer film 14 on which the toner image of the magenta toner 20 is formed reaches the contact portion with the heating roller 12, the heat of the heating roller 12 heats and melts the magenta toner 22. At this time, the magenta toner 20 is fixed on the transfer film 14 with a force stronger than the electrostatic force.

Then, after the toner images of the cyan toner 22 and the magenta toner 20 are heated and melted, as shown in FIG. 6, the third charging process (FIG. 6A) and the third exposure process (FIG. 6). (B)) and developing process (Fig. 6 (c))
After that, the toner image of the yellow toner 18 is developed on the transfer film 14 on which the toner images of the cyan toner 22 and the magenta toner 20 are formed.

Next, in the transfer / fixing process of FIG. 7, the transfer film 14 on which the toner images of the cyan toner 22 and the magenta toner 20 are heated and melted and the toner image of the yellow toner 18 is further formed as described above. It is moved to the pressure contact portion of the heat generating roll 12.

At this time, as shown in FIG. 3, the solenoid 32 is no longer excited, the tension force of the spring 31 rotates the frame 29, and the pressure roller 13 and the fixing cleaner 23 are pressed against the heat roller 12. To be

On the other hand, the recording paper 27 is fed by the paper feed roll 128 in synchronization with the front end of the toner image on the transfer film 14, and is fed by the paper feed roll 129 between the heat generation roll 12 and the pressure roll 13. Then, the toner image on the transfer film 14 is heated and melted by the heat roller 12, and the melted toners 18, 20, 22 permeate between the fibers of the recording paper 27 by the pressure of the pressure roller 13, and are transferred and fixed. To form a color image.

Note that the transfer film after the transfer to the recording paper 27 is completed
A small amount of toner 18, 20, 22 may remain on the surface 14 of the toner, which is wiped off by pressing the fixing cleaner 23 against the transfer film 14.

In addition, as shown in FIG.
Of the 0 and 22, the last developed yellow toner 18 is
It is designed to be directly transferred and fixed to the recording paper 27 without being heated and melted and fixed to the transfer film 14, but this is once heated and melted like the other toners 20 and 22 to be transferred to the transfer film 14. Alternatively, the recording paper 27 may be fixed and then transferred and fixed to the recording paper 27.

By the way, the transfer film 14 is heated by the heat-generating roll 12 in the transfer / fixing process to rise to a temperature of around 160 [° C.]. Therefore, it is necessary to have heat resistance and also to have a certain degree of insulation.
Considering these, it is desirable to use a film made of a material such as polyester, polyimide, polyetherimide, polyethersulfone, or polyetherketone.

In the above embodiment, a film obtained by coating polyimide with Teflon (trade name) is used in consideration of the transfer rate of transfer / presentation. As a result, the transfer rate at the time of transfer / fixing becomes about 100%, the load on the fixing cleaner 23 is reduced, and the life of the fixing cleaner 23 can be extended. Further, the thickness of the transfer film 14 is preferably 200 [μm] or less in consideration of the lines of electric force generated during development, and is [μm] or more in consideration of tensile strength and its handling property. Is desirable.

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made based on the spirit of the present invention, and they are not excluded from the scope of the present invention.

(Effects of the Invention) As described in detail above, according to the present invention, in the color image forming method, the charging step of charging the photoconductor drum and the photoconductor drum are made to correspond to the image signal of a predetermined color. An exposure step of exposing and forming an electrostatic latent image, and an endless transfer film that moves in close contact with the outer periphery of the photosensitive drum, and faces the photosensitive drum via the transfer film. The photosensitive member is arranged by using any one of a plurality of developing means for developing a plurality of colors arranged at a position facing the close contact position between the photosensitive drum and the transfer film. A developing step of adhering a toner of a predetermined color and a toner of a predetermined color corresponding to the electrostatic latent image formed on the drum to form a toner image of the predetermined color on the transfer film. Prepare

Further, a pair of rolls which can take a pressure contact position, a release position, and a release position 2 position are placed at the pressure contact position, and the copy film on which toner images of a plurality of colors are formed and the recording paper are overlapped with each other to form the pair of rolls. A transfer / fixing step of transferring the toner images of a plurality of colors formed on the transfer film onto the recording paper and fixing the toner images.

Then, prior to the transfer / fixing step, the pair of rolls are placed at a release position, and a series of steps of the charging step, the exposing step and the phenomenon step are repeatedly performed corresponding to each color in advance to obtain the transfer film. A toner image of a plurality of colors is formed by sequentially depositing toners of respective colors on top of each other, and at least each toner image of the toner images of the plurality of colors other than the final toner image is formed on the transfer film. Each time a toner image of each color is sequentially formed, it is heated and melted by a heating unit to be fixed on the transfer film, and after the final toner image is formed on the transfer film, the transfer / fixing step is used. The transfer film having the toner images of a plurality of colors on the surface and the recording paper are sandwiched by the pair of rolls placed at the pressure contact position, and passed between the rolls. By, for fixing and transferring the toner images on the recording paper.

In this case, each color toner is subjected in advance to a charging step, an exposure step and a developing step to sequentially form a toner image of each color on the transfer film (provided that at least the last toner image among the toner images is formed. The toner images other than the toner image are once heated and melted and fixed on the transfer film), and then all the toner images are transferred and fixed on the recording paper.

Therefore, the following effects can be obtained.

(1) Since the transfer process and the fixing process can be performed simultaneously, not only is the transfer drum unnecessary in the conventional color image forming method, but also recording paper is mounted on the transfer drum for recording. A mechanism for forming an image and releasing the recording paper is not required, and the color image forming apparatus can be downsized and the cost can be reduced.

Further, it becomes possible to dispose the photoconductor drum, the exposure device, the corona discharger, the static elimination lamp, etc. inside the disposition position of the endless transfer film, which also makes it possible to downsize the color image forming apparatus. it can.

Furthermore, since the recording paper can be easily transported, the frequency of occurrence of jam can be reduced.

(2) It was necessary in the conventional color image forming method. Since the cleaning process of the photoconductor drum is unnecessary,
Not only can the color image forming apparatus be downsized, but the cost can be reduced.

(3) It was necessary in the conventional color image forming method. Since the cleaning process of the photoconductor drum is unnecessary,
It is possible to reduce toner scattering in and out of the color image forming apparatus.

(4) It was necessary in the conventional color image forming method. Since it is not necessary to discard the toner after the photoconductor drum cleaning process, the operator's body, clothes, etc. are not contaminated by the toner, and the maintenance work can be simplified.

(5) Since there is no contact friction on the photoconductor drum that was present in the developing process and cleaning process of the conventional color image forming method, the life of the photoconductor drum can be extended.

(6) It is possible to prevent the image from being disturbed in the electrostatic transfer process of the conventional color image forming method.

(7) Transfer to a rough paper surface such as bond paper, which has been difficult in the electrostatic transfer process of the conventional color image forming method, becomes possible.

(8) Since no pressing operation is required in the process of melting the toner image developed on the transfer film, offset to a pressing member such as a pressing roll does not occur. Therefore, it is not necessary to remove the toner, the maintenance of the pressing member is facilitated, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a color image forming method of the present invention, FIG. 2 is a state diagram during color image formation, FIG. 3 is a state diagram during transfer / fixing, and FIG. 4 is a cyan toner image formation process. FIG. 4A shows the first charging process, and FIG.
FIG. 4B shows the first exposure process, FIG. 4C shows the developing process, FIG. 4D shows the welding process, and FIG. 5 shows the image forming process of magenta toner. FIG. 5 (a) is a diagram showing a second charging process, FIG. 5 (b) is a diagram showing a second exposure process, and FIG. 5 (c).
Shows a developing process, FIG. 5 (d) shows a welding process, FIG. 6 shows a yellow toner image format process, and FIG. 6 (a) shows a third charging process. FIG. 6B is a diagram showing the third exposure process, and FIG. 6C.
Is a diagram showing a developing process, FIG. 7 is a diagram showing a transfer / fixing process, and FIG. 8 is a schematic diagram of a color electrophotographic copying machine in which a conventional color image forming method is adopted. 1, 11 ... Photosensitive drum. 2,15 ... Corona discharger, 4,
5,6,7,17,19,21 …… Developing device, 9,27 …… Recording paper, 12 …… Heating roll, 13 …… Pressure roll, 14 …… Transfer film, 18,20,22 …… toner.

Claims (2)

[Claims] 1. A charging step of (a) charging a photosensitive drum, and (b) an exposing step of exposing the photosensitive drum in accordance with an image signal of a predetermined color to form an electrostatic latent image. (C) On the endless transfer film that moves in close contact with the outer periphery of the photosensitive drum, at a position facing the photosensitive drum through the transfer film, and between the photosensitive drum and the photosensitive drum. Corresponding to the electrostatic latent image formed on the photoconductor drum by using any one of a plurality of developing means for developing a plurality of colors arranged at a position facing the close contact position with the transfer film Then, a developing step of adhering a toner of a predetermined color to form a toner image of a predetermined color on the transfer film, and (d) a pair of rolls which can take two positions of a pressure contact position and a release position are pressed against each other. The toner image of multiple colors on the surface. And a transfer / fixing step of transferring the toner images of a plurality of colors formed on the transfer film to the recording paper and fixing the transferred transfer film and the recording paper, which are overlapped with each other, through the pair of rolls. (E) Prior to the transfer / fixing step, the pair of rolls are placed in the release position, and the series of steps of the charging step, the exposing step and the developing step are repeatedly performed corresponding to each color in advance, Toners of respective colors are sequentially deposited on the transfer film to form toner images of a plurality of colors, and (f) at least each toner image other than the last toner image of the plurality of toner images is Each time a toner image of each color is sequentially formed on the transfer film, it is heated and melted by a heating unit to be fixed on the transfer film, and (g) the final toner image is the transfer film. After being formed on the recording medium, the transfer film and the recording paper, which have toner images of a plurality of colors on their surfaces, are sandwiched by the pair of rolls placed at the pressure contact position by the transfer / fixing process. A color image forming method, wherein each of the toner images is transferred and fixed on the recording paper by passing between the rolls. 2. The color image forming method according to claim 1, wherein the heating means is one of the pair of rolls and is a heat-generating roll which is constantly brought into contact with the back surface of the transfer film.