JPH0816000A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the re-transfer on the first transferring part and to obtain an excellent image by successively performing thermal fixing tentatively for the toner image transferred to the first transferring part of the intermediate transfer body on a heat resistant film when the toner image passes the second transferring part, transferring altogether and simultaneously fixing on the recording paper. CONSTITUTION:The yellow toner image is formed by developing the electrostatic latent image of the yellow image on the photoreceptor drum 1. The yellow toner image is electrostatically transferred on the film 80 in the first transferring part X. The yellow toner image on the film 80 is tentatively fixed at the time of passing the upside of the heating body 83. Similarly, the respective toner image of magenta, cyan and black is successively fixed tentatively on the film 80. The transfer paper P contained in the paper feeding unit 100 is transported to the second transferring part Y of the intermediate transfer part by the paper feeding roller 101. In the second transferring part Y, the toner visual images of four colors formed on the intermediate transferring part are transferred and fixed on the transfer paper P by the heating body 83 and the pressure roller 9.

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 during the transfer of the transfer material carrying the toner from the transfer portion to the fixing portion. 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. The object of the invention is to provide an apparatus which can obtain a good copy image on a plain paper copy using a low-resistance magnetic toner and also at high humidity, and 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 unit for the first color, and then the toner image is electrostatically transferred from the photosensitive member to the intermediate transfer member in the primary transfer portion. For example, yellow, magenta,
The cyan and black toners are sequentially repeated to form a full-color toner image on the intermediate transfer body, and then these full-color toner images are thermally transferred from the intermediate transfer body to a transfer material (for example, paper) in the second transfer portion. Then, the sequence of full color image formation is completed, the transfer material is discharged outside the apparatus, and the required full color image formation is completed.

[0026]

However, a toner image of each color is formed on the intermediate transfer member, and then the secondary transfer unit thermally thermally fixes the intermediate transfer member and the transfer material on the transfer material at the same time. When it is formed, the following problems occur.

(1) In the primary transfer portion on the intermediate transfer body, when the toner images sequentially formed on the photosensitive body are sequentially transferred, the toner image transferred on the previous (one cycle before) transfer body is exposed again. The so-called re-transfer which is transferred onto the body occurs, and a toner image having a faster transfer order has a smaller amount than the proper toner amount transferred at the initial stage and also deteriorates the image quality.

(2) The allowable transfer range for preventing the above retransfer is narrow.

Therefore, a main object of the present invention is to provide an image forming apparatus capable of preventing the occurrence of retransfer at the primary transfer portion of the intermediate transfer member.

Another object of the present invention is to provide an image forming apparatus capable of widening a transfer allowable range capable of preventing occurrence of retransfer and capable of stable image output.

[0031]

The above object can be achieved by an image forming apparatus according to the present invention. In summary, the present invention provides:
A primary transfer portion 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 that electrostatically and sequentially transfers toner images onto the heat-resistant film; An intermediate unit having a secondary transfer unit for thermally transferring and fixing the toner images of a plurality of colors formed on the heat-resistant film to the transfer material all at once from the heat-resistant film by a heating means disposed on the back surface of the heat-resistant film. In an image forming apparatus having a transfer member, a toner image transferred at a primary transfer portion is sequentially thermally presumed on the heat-resistant film when passing through a secondary transfer portion, and then collectively transferred and fixed to a transfer material. And an image forming apparatus.

Here, until the final color toner is transferred to the heat-resistant film in the primary transfer portion, the pressure roller that faces the heating means with the heat-resistant film sandwiched in the secondary transfer portion is It is preferably separated from the film.

The temperature of the heating means at the time of hypothetical wear is
The temperature is preferably equal to or lower than the temperature at the time of batch transfer and simultaneous fixing.

Further, it is preferable that the temperature of the heating means at the time of hypothetical attachment is sequentially raised each time the toner image of each color changes.

Further, it is preferable that the final toner image of the toner images sequentially transferred at the primary transfer portion is also assumedly attached and then collectively transferred and fixed at the same time.

[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. Further, a pressure roller 9 is disposed above and above the intermediate transfer member 8 so as to be able to contact and separate.

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 primary 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

Here, when the front end of the yellow toner image on the film 80 passes over the heating body 83 as a heating means, the heating body 8 is heated.
3 is previously controlled to a heater set temperature described later. This tentatively deposits the yellow toner image on film 80 onto the film.

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 and subjected to image exposure according to the next magenta image signal.

The rotary developing device 5 rotates while the electrostatic latent image is formed on the photosensitive drum 1 according to 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 is performed and the image is transferred onto the film 80 at the primary transfer portion.

At this time, since the previously transferred yellow toner image is assumedly attached on the film, it is not retransferred, and the magenta toner image is transferred with good efficiency, and then the secondary transfer portion Y is transferred. At the time of passing over the heating body 83, it is assumedly attached onto the film.

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 P, which is the transfer material accommodated in, is fed by the paper feed roller 101 and conveyed to the secondary transfer portion Y of the intermediate transfer body via the registration rollers 102, 103 and the paper feed guide 104.

Here, the visible toner images of the four colors formed on the intermediate transfer member are heated by the heating member 83 disposed inside 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 this, 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 body 8 is a film drive roller 81 which also serves as a transfer roller, a driven roller 82 which also serves as a film tension roller, and a heating body (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 core metal made of a conductive rigid material such as metal is used, and polyurethane, EPDM (ethylene propylene dimethyl rubber), polyisoprene, butadiene-styrene copolymer are used. 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 rubber elastic body having heat resistance such as silicone rubber to have 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 them.
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 equipped with a felt pad 84 for cleaning and oil supply impregnated with a release material such as silicone oil so as to abut on the outer surface of the film 80.

The heating element 83 is a low heat capacity linear heating element whose longitudinal direction is 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, 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 (at the time of assumed fixing and The temperature is controlled to 180 ° C. during the secondary transfer.

The temperature control of these heating members is carried out at a predetermined temperature immediately before the leading edge of each toner image on the intermediate transfer member is passed during hypothetical attachment, and immediately before the paper P serving as the transfer material is passed through the secondary transfer portion Y during secondary transfer. Is controlled so that the current is stopped immediately after passing, and the temperature rise of the intermediate transfer body and its surroundings is prevented.

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 measuring 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 it.

The film 80 is not limited to the endless belt shape, but is a long film having an end wound with a roller, and is an intermediate film of a structure in which the film is run from the pay-out shaft to the take-up shaft at a predetermined speed 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 the 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 primary transfer portion X, immediately before passing through the secondary transfer portion Y or the paper P which is the transfer material is fed. Immediately before being fed by the roller 101 and conveyed to the secondary 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 is applied. The film 80 is pressed against the upper surface of the heating body 83 while being pinched, and the film 80 rotates and moves in the forward direction at the same speed as the film speed as the film 80 rotates.

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.

Since the film 80 is particularly excellent in releasability as in this constitution, the transfer efficiency to the transfer material in the secondary transfer is close to 100%.

In the present embodiment, the photosensitive member has been described as a drum, but it is needless to say that if a photosensitive member having a belt shape is applied, the photosensitive member and the intermediate transfer member can be more effectively contacted. Yes.

In this embodiment, the semiconductor laser is used as the latent image forming means. However, the present invention is not limited to this, and 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 an image forming apparatus of a single color or a plurality of colors.

As described above, in this configuration, since retransfer does not occur, a good full color image can be reproduced.
Further, it is possible to widen the permissible transfer range in which retransfer can be prevented. Further, since retransfer can be prevented without adding additional means, the apparatus including the intermediate transfer member can be downsized and simplified.

Second Embodiment In the first embodiment, the temperature of the heating body 83 at the time of assumed attachment and at the time of the secondary transfer (at the time of simultaneous batch transfer and fixing) is set to the same temperature as 180 ° C., but in the present embodiment, it is assumed Heated body 83 when worn
Is lower than the temperature at the time of secondary transfer. Here, the temperature of the heating body 83 at the time of assumed attachment is 150 ° C., and the temperature of the heating body 83 at the time of secondary transfer is 180 ° C.

Here, the temperature of the heating body gradually rises from 150 ° C. to 180 ° C. during the primary transfer of the final color (black), but if it can be maintained at the predetermined 180 ° C. during the secondary transfer, there is no particular problem in image quality.

In this embodiment, the process speed is 50 m.
Although it is set to m / sec, if it takes time to reach a predetermined temperature (becomes from 150 ° C. to 180 ° C.) due to a higher speed system, before the final color, for example, during the primary transfer of the cyan toner, It is also possible to start the temperature rise.

The energizing method and the like in this embodiment are the same as those in the first embodiment.

As described above, by setting the temperature of the heating means at the time of hypothetical attachment to be equal to or lower than the temperature at the time of batch transfer and fixing at the same time, the degree of temperature rise in the apparatus can be suppressed further.

As in the first embodiment, a good full color image can be reproduced because retransfer does not occur.

Embodiment 3 In this embodiment, the temperature of the heating means at the time of hypothetical fixing is increased in the order of the toner of the primary transfer. For example, the hypothetical adhesion temperature of the first yellow toner image is 150.degree. The assumed adhesion temperature of the second magenta toner image is 160 ° C., the assumed adhesion temperature of the third cyan toner image is 170 ° C., the black toner image of the final color is primarily transferred, and 180 ° C. before reaching the secondary transfer portion. As a result, the batch transfer simultaneous fixing is ended.

The energization method in this embodiment is the same as that in the first embodiment.

By adopting this structure, not only re-transfer but also the temperature rise in the machine can be relatively suppressed, and the temperature of the heating body is gradually raised, so that the overshoot of the heating body temperature with respect to the set temperature can be reduced.

Embodiment 4 In this embodiment, after the black toner image, which is the final toner image of the toner images sequentially transferred in the primary transfer portion, is presumed on the film, it is simultaneously transferred onto the transfer paper at the same time. Thus, the difference in the melting state between the final color black toner image that is fixed on the transfer paper without being hypothesized and the other three colors that are fixed on the transfer paper after hypothetical fixing is reduced.

The energization method in this embodiment is the same as that in the first embodiment.

As a result, not only retransfer, but also the quality as a full-color image could be improved.

[0092]

As is apparent from the above description, in the image forming apparatus according to the present invention, the toner image transferred at the primary transfer portion of the intermediate transfer member is sequentially thermally transferred onto the heat resistant film when passing through the secondary transfer portion. By assuming and wearing and then simultaneously fixing to the transfer material by batch transfer, it is possible to prevent the occurrence of retransfer at the primary transfer portion and obtain a good image. In addition, the permissible range of transfer that can prevent the occurrence of retransfer can be widened, and stable image output can be performed.

Since retransfer can be prevented without adding additional means, the apparatus including the intermediate transfer member can be downsized and simplified.

[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 an intermediate transfer member used in the image forming apparatus of FIG.

FIG. 3 is an enlarged view of a film used in the intermediate transfer body of FIG.

[Explanation of symbols]

 1 Photoreceptor Drum (Image Carrier) 8 Intermediate Transfer Body 9 Pressure Roller 80 Heat Resistant Film 81 Drive Roller (Transfer Roller) 82 Driven Roller 83 Heater X Primary Transfer Part Y Secondary Transfer Part

Claims (5)

[Claims] 1. A primary device including 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, on which toner images are electrostatically sequentially superposed and transferred. Secondary transfer in which the toner images of a plurality of colors formed on the transfer portion and the heat-resistant film are thermally transferred and fixed from the heat-resistant film to the transfer material all at once by the heating means arranged on the back surface of the heat-resistant film. In an image forming apparatus having an intermediate transfer member, the toner image transferred by the primary transfer unit is thermally presumed on the heat-resistant film sequentially when passing through the secondary transfer unit, and then collectively transferred to a transfer material. An image forming apparatus characterized by simultaneous transfer and fixing. 2. The heat-resistant film includes a pressure roller that faces the heating means with the heat-resistant film sandwiched in the secondary transfer portion until just before the final color toner is transferred to the heat-resistant film in the primary transfer portion. The image forming apparatus according to claim 1, wherein the image forming apparatus is separated from the image forming apparatus. 3. The image forming apparatus according to claim 1, wherein the temperature of the heating unit at the time of assumed attachment is equal to or lower than the temperature at the simultaneous transfer and fixing. 4. The image forming apparatus according to claim 1, wherein the temperature of the heating means at the time of hypothetical attachment is sequentially raised each time a toner image of each color changes. 5. The image forming apparatus according to claim 1, wherein the final toner image of the toner images sequentially transferred at the primary transfer portion is also postulated and simultaneously fixed at a batch transfer. .