JPH0815999A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the adherence of ozone and nitrogen oxides on the surface of an intermediate transfer body by performing the transfer on the heat resistant film inserted between a transfer roller and an image carrier while applying the transfer bias. CONSTITUTION:The intermediate transfer body 8 of the full color image forming device is provided with the film drive roller 81 used as the transfer roller, the driven roller 82 used as the film tension roller and the film material 80 of a endless belt type winding extended round the thermal heater 83. Moreover, the intermediate transfer body 8 is provided with the felt pad 84 for cleaning in common use for feeding oil, impregnated with the releasing agent such as the silicone oil, so as to come in contact with the outer surface of the film 80. In consequence of this constitution, at the time of transferring, the evolution of the ozone and the generation of the nitrogen oxides can be reduced, these can be prevented from sticking on the film 80 with time, and the film 80 is stably held in contact with the image carrier 1 surface, therefore, the excellent transferring state can be continued.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine or a printer, and in particular, it sequentially transfers toner images of a plurality of colors from an image carrier to an intermediate transfer body and then collectively. The present invention relates to a multicolor image forming apparatus that transfers and fixes an intermediate transfer member onto a transfer material.

[0002]

2. Description of the Related Art Conventionally, the following techniques are known as techniques for transferring a multicolor toner image using an intermediate transfer member.

1) According to Japanese Patent Publication No. 49-209,
A technique is disclosed in which electrostatic transfer is performed in the primary transfer and pressure transfer is performed in the secondary transfer. This is a cloth,
When multicolor printing is performed on a flexible material having elasticity such as paper, it is an improvement of the so-called color shift in which an image shifts when transferring each color in a superimposed manner.

That is, an object of the present invention is to transfer images of respective colors to a blanket drum intermediately and transfer them at once so as to reduce color misregistration and to print high-speed multi-color images.

2) Japanese Patent Laid-Open No. 50-23234 discloses that
It is disclosed that the secondary transfer portion has a pressing / heating means. That is, when the transfer process and the fixing process are separated, Paper powder and the like adversely affect the photosensitive drum in the transfer process.

[0006] 2. The thermal efficiency during fixing is poor.

3. The image is disturbed while the transfer material carrying the toner is conveyed from the transfer unit to the fixing unit. It is an improvement of such a defect.

The object of the present invention is to transfer and fix the developed image formed on the surface of the photoconductor to the transfer material as a faithful and clear image.

3) JP-A-59-12576 discloses that
It is disclosed that primary transfer is performed by pressure and transfer and fixing are performed by secondary transfer.

This is because registration is difficult when multiple transfer is performed on the same transfer material, and the transfer material does not have sufficient force to hold the toner image to be transferred, so that the transfer material may not be transferred during the next transfer. This is an improvement of the above-mentioned drawback that the toner image is peeled off.

In this technique, since each toner image is transferred onto the intermediate transfer member, the transfer position alignment accuracy of each toner image onto the intermediate transfer member can be easily obtained, and a high quality image can always be reproduced with good reproducibility. Can be formed on the transfer material.

Further, since each toner image is further transferred to the next transfer material after the transfer of each toner image to the intermediate transfer member, the synchronization margin becomes large particularly when the transfer material is transferred, and the transfer mechanism can be simplified and reliability is improved. improves.

Further, since the intermediate transfer member has a transfer layer (especially rubber type) capable of strongly holding the transferred toner image, it has excellent transfer characteristics.

The following are known techniques for simultaneous transfer and fixing.

1) Japanese Patent Application Laid-Open No. 49-78559 discloses that
The surface energy (adhesive force), hardness, and heat quantity of the intermediate transfer member are specified.

2) JP-A-57-23975 and JP-A-59-50473 disclose an intermediate transfer layer containing an addition polymerization type silicone rubber.

The addition polymerization type silicone rubber has few unreacted parts and leached parts, so that the photosensitive layer is less contaminated, and the transfer layer is excellent in film strength and processability and a good image can be obtained.

3) Japanese Patent Laid-Open No. 59-139070 discloses that primary transfer is performed by electrostatic transfer and pressure fixing is performed by secondary transfer. It is therefore an object of the present invention to provide a device which can obtain a good copy image even in plain paper copying using a low-resistance magnetic toner and in high humidity, and which can be easily made compact.

4) Japanese Patent Application Laid-Open No. 62-293270 discloses that the intermediate transfer member has a transfer layer of silicone rubber on a polyamide fiber woven fabric substrate. here,
Since polyamide fiber woven cloth is used as the base material of the intermediate transfer material, it is flexible and has good adhesion to the image carrier and the transfer material, thus improving transfer efficiency. It is said that the adhesiveness is good and the endless belt can be easily formed.

As described above, many examples of the intermediate transfer member and the example of simultaneous transfer and fixing in the case of a multicolor toner image have been proposed.

In many cases of monochromatic image forming means, an intermediate transfer member having adhesiveness and releasability is used,
There is a system in which the toner image on the photosensitive drum is once adhesively transferred onto the intermediate transfer member, and then the intermediate transfer member is fused and fixed on the transfer material. In the primary transfer portion, which is an adhesive transfer, the intermediate transfer body made of silicon rubber and the photosensitive drum are brought into pressure contact with each other, and the toner image is adhered onto the intermediate transfer body by adhesiveness. Next, in the secondary transfer portion which is the melt transfer, the heat roller and the intermediate transfer body are brought into pressure contact with each other, and the toner image is heated and melted by the heat roller via the transfer material. The melted toner penetrates into the fibers of the transfer material due to the pressure. At the same time, it is peeled off from the intermediate transfer member due to the releasing property of the intermediate transfer member.

In the case of a multicolor image forming means, it is difficult to use adhesive transfer at the primary transfer portion, so that electrostatic transfer is often used. Simultaneous transfer fixing device
The transfer efficiency of electrostatic transfer is relatively low at 80 to 90%,
It has been proposed to solve the problems that the transfer efficiency is affected by the resistance / capacitance change due to the change of the water content of the transfer material, and the scattering is caused.

Further, as a device for preventing color misregistration and color unevenness of a conventional multicolor image forming apparatus using an intermediate transfer member, for example, as described in JP-A-57-673, Some are designed to prevent meandering.

Further, as an example of succeeding in maintaining the accurate resist control required for a full color machine with each color multiplex using relatively inexpensive parts, US Pat. No. 4,65.
No. 2,115 and No. 4,788,572, which use a method of synchronizing a photosensitive belt and an intermediate transfer belt.

As a multi-color image forming apparatus using these intermediate transfer bodies, for example, a multi-transfer type copying machine, a document is CC-printed.
After being read by a D-line sensor or the like, the image signal that has been subjected to various kinds of processing and the image signal directly output from the computer are output to the laser driver, and the laser is driven and laser exposure is performed in advance. A latent image is formed on the charged photoreceptor. Next, this latent image is developed with the toner in the developing device for the first color, and then the toner image is electrostatically transferred from the photosensitive member to the intermediate transfer member in the first transfer portion.

These series of steps are sequentially repeated with, for example, yellow, magenta, cyan, and black toners to form a full-color toner image on the intermediate transfer member, and then these full-color toner images are formed at the second transfer portion. Thermally transfer from the intermediate transfer body to a transfer material (for example, paper) and fix them all at once, and the sequence of full-color image formation is completed. This transfer material is ejected out of the machine and the required full-color image formation is completed. To do.

[0027]

However, as shown in FIG. 5, in the first transfer portion R, the conventional corona discharger T is used.
When a toner image of each color is formed on the intermediate transfer member S by the transfer by the above method, the following problems occur.

(1) Since ozone and nitrogen oxides are generated by corona discharge, they adhere to the discharge surface of the film of the intermediate transfer member over time, making it difficult to form an electric field in the transfer direction, resulting in transfer failure. appear.

(2) The contact between the surface of the photosensitive member and the film of the intermediate transfer member is unstable. That is, the pressing force of the elastic sheet for pressing the film toward the image carrier changes.

(3) The apparatus including the intermediate transfer member becomes relatively large.

Therefore, a first object of the present invention is to provide an image forming apparatus capable of preventing ozone and nitrogen oxides from adhering to the film surface of an intermediate transfer member over time.

A second object of the present invention is to provide an image forming apparatus capable of stabilizing the contact between the surface of the photoconductor and the film.

Further, a third object of the present invention is to provide an image forming apparatus capable of reducing the size of the apparatus main body including the intermediate transfer member.

[0034]

The above object can be achieved by an image forming apparatus according to the present invention. In summary, the present invention provides:
A first transfer unit that includes an image carrier on which toner images of a plurality of colors are sequentially formed, and a heat-resistant film having a highly releasable surface, and electrostatically and sequentially transfers the toner images onto the heat-resistant film, And an intermediate transfer member having a second transfer portion for collectively thermally transferring and fixing the toner images of a plurality of colors formed on the heat-resistant film onto a transfer material at the same time. The image forming apparatus is characterized in that the transfer means in the section is a transfer roller that presses the heat-resistant film between the heat-resistant film and the image carrier and applies a transfer bias.

The relative speed between the rotational speed of the image carrier and the moving speed of the heat resistant film is preferably increased or decreased by 1 to 10%.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus according to the present invention will be described below in more detail with reference to the drawings.

Embodiment 1 FIG. 1 is a block diagram showing a first embodiment of a full-color image forming apparatus to which the present invention is applied.

The photoconductor drum 1 as an image carrier is made of a photoconductor such as OPC or a-Si, and its periphery is irradiated with a pre-exposure lamp 7, a corona charger 2, and a laser beam corresponding to each color signal. A rotary developing device 5 having an exposure unit composed of a laser scanner 3, a mirror 4 and the like, and four developing devices for respectively accommodating yellow, magenta, cyan, and black toners, an intermediate transfer member 8, and a cleaning unit 6. Etc. are arranged. A pressure roller 9 is disposed above the intermediate transfer member 8 so as to be able to come into contact with and separate from the intermediate transfer member 8.

An image forming sequence of the entire image forming apparatus having the above configuration will be described. When the photosensitive drum 1 rotates in the direction of the arrow and is uniformly charged by the primary charger 2,
Image exposure is performed by the laser beam E whose pulse width is modulated according to the yellow image signal of the original, and an electrostatic latent image of the yellow image is formed on the photosensitive drum 1. The electrostatic latent image of the yellow image is developed by the yellow developing device 5Y which is previously fixed at the developing position by the rotation of the rotary developing device 5. At this time, the developing bias applied to the developing sleeve of the yellow developing device 5Y is a bias in which V _DC = 400 V is superimposed on a rectangular wave alternating voltage having an alternating voltage value V _PP of 2 KV and a frequency f of 2 KHz.

Further, the toner in the developing device consumed by the development is replenished from the toner hopper 51. This yellow image is electrostatically transferred at the first transfer portion X, which is the contact portion between the photosensitive drum 1 and the intermediate transfer member 8. Here, the intermediate transfer member 8 rotates in the direction of the arrow in synchronization with the photosensitive drum 1, and continues to rotate while holding the yellow toner image on the surface, and transfers the next color (magenta in FIG. 1). Prepare for

On the other hand, the surface of the photosensitive drum 1 is cleaned by the cleaning means 6 and then uniformly charged again by the primary charger 2 to be imagewise exposed in accordance with the next magenta image signal.

The rotary developing device 5 rotates while the electrostatic latent image is formed on the photosensitive drum 1 in accordance with the image signal of magenta by the above-mentioned image exposure, so that the magenta developing device 5M is fixed at the developing position and predetermined. Magenta development of.

Subsequently, the above-described process is carried out for the cyan color and the black color, respectively, and the transfer of the four colors to the intermediate transfer member is completed or during the transfer of the final color black, the paper feeding unit 100 The paper P as a transfer material accommodated in the paper is fed by the paper feed roller 101 and conveyed to the second transfer portion Y of the intermediate transfer body via the registration rollers 102 and 103 and the paper feed guide 104.

Here, the visible toner images of four colors formed on the intermediate transfer member are heated by the heating member 83 disposed in the intermediate transfer member 8.
Pressure roller 9 which is brought into contact with the heat of the paper P and the conveyance of the paper P
Is transferred and fixed on the paper by and the discharge rollers 105, 10
The sheet is discharged onto the discharge tray 107 through 6 and the full-color image formation on the paper is completed.

After that, the heat-resistant film 8 of the intermediate transfer member
The toner resin remaining on the surface 0 is cleaned by bringing the intermediate transfer member cleaning means 84, such as a felt pad, into contact with the toner resin to prepare for the next step.

Next, the intermediate transfer member 8 used in the image forming apparatus will be described with reference to FIG.

FIG. 2 is a schematic diagram of an intermediate transfer member having an endless bell type film material.

The intermediate transfer member 8 is a film driving roller 81 which also functions as a transfer roller, a driven roller 82 which also functions as a film tension roller, and a heating member (thermal heater) 8.
3 is provided with an endless belt type thin film heat resistant film material (hereinafter referred to as a film) 80 stretched around.

The drive roller 81, the driven roller 82, and the heating body 83 are arranged substantially parallel to the rotation axis of the photosensitive drum 1. Instead of using the transfer roller 81 as the driving roller, the driven roller 82 may be used as the driving roller. Both ends of each of the drive roller 81 and the driven roller 82 are rotatably supported by bearings by bearing members (not shown). The heating body 83 is a fixing member fixedly supported by a stationary member (not shown). The driving roller 81 is rotationally driven in the clockwise direction in the drawing by a driving system (not shown), whereby the film 80 is given a conveying force by the frictional force between the outer peripheral surface of the driving roller 81 and the inner surface of the film, and the inner surface of the film is heated. While sliding on the heating surface of 83, the drive roller 81, the driven roller 82, and the heating member 83 are moved between the three members in the clockwise direction of the arrow in the drawing, and the transfer speed of the transfer paper P as the material to be heated (in this embodiment). Is rotated at the same peripheral speed of 50 mm / sec).

Since the driving roller 81 of this embodiment also serves as a transfer roller, a cored bar made of a conductive rigid material such as metal is coated with polyurethane, EPDM (ethylene propylene dimethyl rubber), polyisoprene, butadiene-styrene copolymer. Rubber elasticity of polybutadiene, isobutylene-isoprene copolymer, butadiene-acrylonitrile copolymer, ethylene-propylene copolymer, chlorosulfonated polyethylene, acrylic ester copolymer, organic polysiloxane, vinylidene fluoride copolymer, etc. Volume resistance RV is achieved by dispersing conductive particles such as carbon in the member.
Of 10 ⁵ to 10 ¹⁰ Ωcm and Asker C hardness of ^{10 to} 6
It is composed of an elastic layer formed of, for example, a foaming or rubber elastic body adjusted to 5 degrees, preferably 20 to 50 degrees.

In this embodiment, the driving roller 81 places importance on heat resistance and disperses conductive particles in a heat-resistant rubber elastic body such as silicone rubber to obtain a volume resistance of 10 ⁷ to 10 ⁹ Ω.
cm, Asker C hardness 40 to 50 degrees, outer diameter 30 mm,
It is a 7 mm thick silicone rubber single layer.

The contact pressure of the drive roller 81 with the photosensitive drum 1 is 10 when the film 80 is sandwiched between the two.
The pressure is applied at gf to 2 kgf, preferably 0.3 gf to 1 kgf.

A bias of 1 to 2 kV is applied from the transfer bias power source 85 to the core of the drive roller 81, which is the transfer roller. This bias gradually increases according to the order of toner stacking, and is 1 kV for the first color, 1.5 kV for the second color, 2 kV for the third color, and 2.5 kV for the fourth color.
And

When there is only a single color, the voltage is 1 kV as in the first color. These transfer biases are controlled by a constant voltage or a constant current. Further, although only DC is used as the transfer bias in this embodiment, an AC component may be superimposed.

Further, the intermediate transfer member 8 is provided with a felt pad 84 for cleaning and oil supply impregnated with a release material such as silicone oil so as to come into contact with the outer surface of the film 80.

The heating element 83 is a low heat capacity linear heating element having a longitudinal direction in the axial direction of the film 80 (direction orthogonal to the rotational movement direction of the film, hereinafter referred to as film width direction).

The heating element 83 includes a heater substrate 83a, an energization heating element layer 83b formed in a strip shape or a linear shape along the longitudinal direction at a substantially central portion of the upper surface of the substrate, and the energization heating element layer 83b. Heat-resistant glass 83c, which is a surface protection layer in which the upper surface of the substrate including the substrate is covered with a thickness of about 10 μm, and the substrate 83a.
The temperature detecting element 83d provided on the lower surface of the substrate, the heater support 83e for adiabatically supporting the substrate, and the like.

The heater substrate 83a is a member having heat resistance, insulation, and low heat capacity, and as an example, the thickness is 1 mm and the width is 5 to 1.
An alumina substrate having a length of 0 mm and a length of 310 mm can be used.

The heating element layer 83b is a coating layer made of an electric resistance material such as Ag / Pd (silver palladium) .Ta ₂ N and having a thickness of 10 μm and a width of 1 to 3 mm formed by screen printing or the like.

The temperature detecting element 83d is made of, for example, a resistance thermometer having a low heat capacity such as a Pt film coated on the lower surface of the substrate by screen printing or the like, and a silicone-based adhesive having good thermal conductivity at the substantially central portion of the lower surface of the substrate. It is an adhered low heat capacity NTC thermistor or the like.

The heater support 83e heat-insulates and supports the heating element components 83a to 83d with respect to the fixing device and the entire copying apparatus, and has heat insulating properties, high heat resistance, and rigidity, such as polyphenylene sulfide and polyamide imide. , A high heat resistant resin such as polyimide, polyetheretherketone, and liquid crystal polymer, or a composite material of these resins and ceramics, metal, glass, or the like.

When the heating element layer 83b is energized, heat is generated and the temperature of the heater substrate 83a rises. The temperature of the heater substrate 83a is detected by the temperature detecting element 83d and fed back to a control circuit (not shown) to control the energization of the heating element layer 83b so that the temperature of the heating element 83 reaches a predetermined fixing temperature (for example, 180 ° C.). ) Is controlled.

The temperature of these heating members is controlled so that the paper P, which is the transfer material, reaches a predetermined temperature immediately before passing through the second transfer portion Y, and immediately after passing, the energization is stopped to raise the temperature of the intermediate transfer member and the surroundings. To prevent.

Here, the energization is, for example, a pulsed waveform with a cycle of 20 ms of 100 V DC, and a pulse according to a desired temperature and energy release amount controlled by the temperature measuring element 83d is given by changing its pulse width. In general, the pulse width is 0.5 to 5 ms. Alternatively, AC100V
Then, the energization power is controlled by controlling the energizing phase angle by the energization control circuit (not shown) including the triac according to the heater substrate detection temperature of the temperature detecting element 83d.

In the heating element 83, the heat capacity of the heater substrate 83a, the heating element layer 83b, the surface protective layer 83c, and the temperature detecting element 83d is small, and this is insulated by the support element 83e. The temperature reaches a temperature at which the toner layer on the film 80 and the transfer paper P can be fixed in a short time (quick start property), and there is no need for standby temperature control in which the heating body 83 is previously energized to generate heat, and energy can be saved. At the same time, it is possible to prevent internal temperature rise of the intermediate transfer body 8 and the photosensitive drums 1 and the like around the intermediate transfer body 8.

The film 80 is not limited to an endless belt, but is an endless long film wound with a roller, and has an intermediate structure in which it is run at a predetermined speed from the feeding shaft to the winding shaft via a heating body. It can also be a transfer body.

The pressure roller 9 has a highly releasable skin layer such as PFA or PTFE formed on a heat-resistant rubber elastic body such as silicone rubber, like a pressure roller in a general fixing device. Then, the film 80 is brought into contact with and separated from the heating surface of the heating body 83 by sandwiching the film 80.

The timing of this contact / separation is such that after the toner image of the fourth color (black in this case) is formed on the film 80 in the first transfer portion X, immediately before passing through the second transfer portion Y or when the paper P serving as the transfer material is fed. Immediately before being fed by the paper roller 101 and conveyed to the second transfer portion Y of the intermediate transfer body via the registration rollers 102 and 103 and the paper feed guide 104, a contact force of, for example, 2 to 20 kgf, preferably 4 to 8 kgf. The film 80 is sandwiched between the heating element 83 and the upper surface of the heating element 83, and the film 80 is rotated in the forward direction along with the rotational speed of the film 80 at substantially the same speed as the film speed.

Next, the layer structure of the film 80 will be described with reference to FIG. The film 80 is composed of a base layer (base film) 80a and a high release layer 80b having a heat resistance of, for example, 5 μm. The base layer 80a is a heat-resistant resin, for example, polyester, PET (polyethylene terephthalate), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, PTFE (polytetrafluoroethylene), polyphenylene sulfide, polyamide imide, polyimide, polyether. It is made of a highly heat-resistant resin such as ketone or liquid crystal polymer, a metal sheet such as aluminum or nickel, or a composite material of these and ceramics, metal, glass or the like.

Further, as the high release layer 80b, for example, the same fluororesin or fluororubber such as PET or PTFE as the above-mentioned base layer, silicone resin or silicone rubber is used.

Further, as a more preferable film structure, these heat resistant sheets have a low resistance layer, and the volume resistance RV equivalent to that of the driving roller 81 is 10 ^5.
It is to be about 10 ¹⁰ Ωcm.

These films 80 have a total thickness of 100 μm or less, preferably 40 μm or less. In this embodiment, the base layer (base film) 8 of the film 80 is used.
0a is a polyimide film having a thickness of 20 μm, and high release layer 80b is 5 μ having a low resistance due to carbon dispersion.
An m-thick PFA layer is applied.

In the present embodiment, the photosensitive member has been described as a drum type member, but it goes without saying that if a belt type photosensitive member is adopted, the contact state between the photosensitive member and the intermediate transfer member will be more effective. Yes.

In this embodiment, the semiconductor laser is used as the latent image forming means, but the invention is not limited to this, and the latent image forming means may be a digital latent image forming means such as an LED, a liquid crystal, or ionography, and a reader. It is also effective in so-called analog latent image forming means for directly forming an image signal as light on the photoconductor without using such image reading means.

Further, although the full-color image forming apparatus including the developing system of four colors is described in this embodiment, it is needless to say that the present invention can be applied to a single-color or plural-color image forming apparatus.

As described above, in this configuration, ozone and nitrogen oxides can be reduced, so that they can be prevented from adhering to these films over time, and the contact between the surface of the image bearing member and the film is stable. The continuous transfer state can be maintained. Also,
The device including the intermediate transfer member can be downsized and simplified.

Embodiment 2 In Embodiment 1, the intermediate transfer member 8 rotates in the direction of the arrow in synchronization with the photosensitive drum 1 (the film 80 driven by the drive roller 81 rotates at the same speed as the photosensitive drum 1). However, the present embodiment is characterized by preventing the transfer omission by increasing or decreasing the relative speed of the drive roller 81 with respect to the photosensitive drum 1.

This transfer omission means that the central portion of the toner image forming a character or line image cannot be transferred and the photosensitive drum 1
This is a phenomenon that remains above, and tends to worsen as the contact pressure between the photosensitive drum 1 and the drive roller 81 via the film 80 increases.

This can be prevented by generating the displacement stress on the toner image by changing the relative speed between the photosensitive drum 1 and the film 80 as in this embodiment.

In the present embodiment, this photosensitive drum 1
And the relative speed of the film 80 is 1 to 10%, preferably 2
This problem was solved by increasing or decreasing by about 5%.

Further, the image blemishes and blemishes that occur at this time can be corrected and eliminated by previously bleaching and bleaching the latent image during latent image formation.

Also in this configuration, not only the above-mentioned problems can be solved but also image defects such as transfer defects can be prevented.

Embodiment 3 In this configuration, as shown in FIG. 4, the discharge roller 1 of Embodiment 1
It is characterized in that the arrangement of 05 and 106 is omitted, the driven roller 82 is arranged instead of the arrangement position of the discharge rollers 105 and 106, and the film 80 is further extended. This is a simplified configuration of the transport means.

As a result, there is a period in which the toner image on the transfer material that is heated and melted in the second transfer portion is sufficiently cooled, and the transfer material is easily separated from the film 80.

Also in this structure, not only the problems as described above can be solved, but also the transfer material can be easily separated from the film, and the transfer material transport structure can be simplified.

[0086]

As is apparent from the above description, in the image forming apparatus according to the present invention, the transfer means in the first transfer section presses the heat-resistant film between the image carrier and the transfer bias. Since the transfer roller can reduce the generation of ozone and nitrogen oxides, it is possible to prevent the adhesion of these to the heat-resistant film over time, prevent the transfer failure, and obtain a good image. Further, since the contact between the surface of the image carrier and the film is stable, a good transfer state can be continued. Furthermore, the size and simplification of the device including the intermediate transfer member can be achieved.

[Brief description of drawings]

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

FIG. 2 is an enlarged view of a main part showing an intermediate transfer member used in the image forming apparatus of FIG.

3 is a configuration diagram of a heat-resistant film used in the intermediate transfer member of FIG.

FIG. 4 is a schematic configuration diagram showing another embodiment of the image forming apparatus according to the present invention.

FIG. 5 is a schematic configuration diagram of an intermediate transfer member used in a conventional image forming apparatus.

[Explanation of symbols]

 1 Photoreceptor Drum (Image Bearing Body) 8 Intermediate Transfer Body 9 Pressure Roller 80 Heat Resistant Film 81 Drive Roller (Transfer Roller) 82 Driven Roller 83 Heating Body X First Transfer Section Y Second Transfer Section

Claims (2)

[Claims] 1. A method comprising: an image carrier on which toner images of a plurality of colors are sequentially formed; and a heat-resistant film having a highly releasable surface, wherein the toner images are electrostatically sequentially superposed and transferred onto the heat-resistant film. An image forming apparatus having one transfer part and an intermediate transfer member having a second transfer part for collectively thermally transferring and fixing the toner images of a plurality of colors formed on the heat-resistant film onto a transfer material. The image forming apparatus is characterized in that the transfer means in the first transfer portion is a transfer roller which presses the heat resistant film between the heat resistant film and the image carrier and to which a transfer bias is applied. 2. The image forming apparatus according to claim 1, wherein the relative speed between the rotational speed of the image carrier and the moving speed of the heat resistant film is increased or decreased by 1 to 10%.