JP2002040720A - Double-sided image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a double-sided image by transferring toner images to an intermediate transfer body and a transfer member irrespective of corona discharge of an electrode, and fixing the toner images transferred to the transfer member, under low temperature and under pressure. SOLUTION: Color toner images are formed through development and superimposition on a photoreceptor drum 10 by developing units 13, which respectively accommodate liquid developers in separate colors, on a photoreceptor drum 10. The color toner images are held on the photoreceptor drum 10 and the intermediate transfer belt 14 as a front image and a rear image, respectively. An image transfer area 140 is constituted between the transfer roller 14C and the photoreceptor drum 10, which is in contact therewith. The transfer roller 14C holds the rear image on the intermediate transfer belt 14, comes into contact with the inside of the intermediate transfer belt 14, incorporates a heater H, and is pressed by an elastic member S. The front image and the rear image are transferred and fixed on the upper side and the lower side, respectively, of fed recording paper P at the same time under pressure and heat.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to copying in which a charging means, an image writing means and a developing means are arranged around an image forming body to transfer and fix a toner image formed on the image forming body onto a transfer material. More particularly, the present invention relates to an image forming apparatus capable of forming an image on both sides of a transfer material via an intermediate transfer member.

[0002]

2. Description of the Related Art Conventionally, in double-sided image formation, an image on one side formed on an image forming body is transferred and fixed on a transfer material, and this is temporarily stored in a double-sided reversal feeding device and formed again. A method has been adopted in which a transfer material is fed from a two-sided reversing feed device in synchronization with an image formed on a body, and an image on the other surface is transferred and fixed onto the transfer material.

In this double-sided image forming apparatus, as described above,
The transfer of the transfer material, such as feeding to the two-sided reversing feed device or passing through the fixing device twice, is performed, so that the reliability of transfer of the transfer material is low, causing jams and wrinkles of the transfer material. .

On the other hand, JP-B-49-37538 and JP-B-54-28740, and JP-A-1-44457.
Japanese Patent Application Laid-Open Publication No. 4-214576 and the like propose a method in which a toner image is formed on both surfaces of a transfer material using an image forming body and an intermediate transfer body, and then fixed once.

Further, the present inventors have arranged a plurality of sets of toner image forming means including a charging means, an image writing means, a developing means, etc. around a photosensitive drum (image forming body), and provided on the photosensitive drum. Once the formed superimposed color toner image is once transferred onto the belt-shaped intermediate transfer member, a superimposed color toner image is formed again on the photoconductor drum, and the toner image on the photoconductor drum and the intermediate transfer member are formed. The toner image on the photosensitive drum is transferred to both sides of the transfer material conveyed by the intermediate transfer member at the same time as the toner image of the intermediate transfer member, and the toner image on the intermediate transfer member is transferred to the back surface. Japanese Patent Application Laid-Open No. 9-258 discloses an image forming apparatus and an image forming method for separating a transfer material from an intermediate transfer body, fixing a toner image on the transfer material and forming a double-sided color image after transferring the image.
No. 492 and JP-A-9-258516.

[0006]

However, since the corona discharger is used for both the transfer means and the charge removing means, ozone is generated, and the fixing means uses a high-temperature heat roller. However, there is a problem that the quality of the material deteriorates and the copy quality deteriorates. In particular, in a double-sided image forming apparatus, the number of times of transfer increases, and the problem of ozone generation during transfer cannot be ignored. Also, a toner image developed by a dry developer tends to easily cause so-called transfer omission when the transfer efficiency is low and the flatness of the transfer material is poor.

When a wet developer is used instead of a dry developer, harmful ozone and high-temperature heat can be prevented. As for the problem in the case of using a wet developer, a solution has been proposed in Japanese Patent Application Laid-Open No. 2000-105511 and others.

An object of the present invention is to provide a double-sided image forming apparatus which generates a small amount of ozone using a wet developer or the like and does not require high-temperature processing.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a double-sided image forming apparatus for transferring and fixing a toner image formed on an image forming body to both sides of a transfer material via an intermediate transfer body. The toner image is achieved by a double-sided image forming apparatus wherein the toner image is transferred and fixed to a transfer material by applying heat and pressure from both sides at the same location.

[0010]

Embodiments of the present invention will be described below. Note that the description in this column does not limit the technical scope of the claims and the meaning of terms. Further, the following assertive description in the embodiment of the present invention indicates the best mode, and does not limit the meaning or technical scope of the terms of the present invention. In the following description of the embodiment, the surface of the transfer material on the side facing the image forming body in the transfer area is called the front surface, and the other surface of the transfer material, that is, the surface of the transfer material on the side facing the intermediate transfer body is called the back surface. The image transferred to the front surface of the transfer material is called a front image, and the image transferred to the back surface of the transfer material is called a back image.

1 and 2 show an image forming process and each mechanism of an embodiment of an image forming apparatus according to the present invention.
This will be described with reference to FIG. FIG. 1 is a sectional view of a color image forming apparatus showing a first embodiment of a two-sided image forming apparatus according to the present invention, and FIG. 2 is a side sectional view of the image forming body of FIG.

In FIG. 1, reference numeral 10 denotes a photosensitive drum as an image forming body; 11, a scorotron charger as charging means for each color; 12, an exposure optical system as image writing means for each color; A developing device 14 is an intermediate transfer belt which is an intermediate transfer member.

The photosensitive drum 10, which is an image forming body, has a transparent conductive layer, a, on the outer periphery of a cylindrical base formed of a transparent member such as optical glass or transparent acrylic resin.
A photosensitive layer such as an Si layer or an organic photosensitive layer (OPC), which is rotated at a linear speed of 80 to 400 mm / sec in a clockwise direction indicated by an arrow in FIG. Is done.

The photosensitive drum 10, as shown in FIG.
Flange members 10a and 1 at both ends for engaging and fixing it
The gear G integrated with the flange member 10b is supported by the bearings B1 and B2 fitted to the drum shaft 30 and is rotatably supported by the drum shaft 30 erected and fixed to the apparatus main body. When driven by meshing with the drive gear, it is rotated at a constant speed in a predetermined direction.

The means for forming a toner image on the image forming body includes:
It is composed of a scorotron charger 11 as a charging unit, an exposure optical system 12 as an image writing unit, and a developing unit 13 as a developing unit. These units constitute a set of yellow (Y), magenta (M), and cyan (C). And four sets for the image forming process of each color of black (K), Y, M, C, and Y with respect to the rotation direction of the photosensitive drum 10 indicated by an arrow in FIG.
They are arranged in the order of K.

The scorotron charger 11, which is a charging means for each color, has a control grid maintained at a predetermined potential and a discharge electrode 11a composed of, for example, a sawtooth electrode, and faces the photosensitive layer of the photosensitive drum 10. And installed
The charging operation (in the present embodiment, negative charging) is performed by corona discharge having the same polarity as that of the toner.
A uniform potential is given to 0. As the discharge electrode 11a, a wire electrode or a needle electrode may be used.

Exposure optical system 1 as image writing means for each color
2 indicates that the exposure position on the photosensitive drum 10 is the photosensitive drum 1 with respect to the scorotron charger 11 for each color described above.
It is arranged inside the photoconductor drum 10 so as to be located on the downstream side in the rotation direction of 0. As shown in FIG. 2, each exposure optical system 12 includes a plurality of LEDs (light emitting diodes) as light emitting elements of image exposure light (image writing light) arranged in the main scanning direction in parallel with the drum axis 30. Linear exposure elements 12a arranged in an array, and a light converging light transmitter (trade name: Selfoc lens array) 12b as an imaging element
And a lens holder 12c, which is attached to the holding member 20A. The exposure optical system 12 for each color writes an image on the photosensitive layer of the photosensitive drum 10 from the back surface in accordance with the image data of each color read by a separate image reading device and stored in the memory. An electrostatic latent image is formed. As the exposure element 12a, an element in which a plurality of light-emitting elements such as FL (phosphor light emission), EL (electroluminescence), and PL (plasma discharge) are arranged in an array can be used in addition to the LED. The emission wavelength of the light-emitting element for the image exposure light (image writing light) is usually high for the Y, M, and C toners.
Although a range of 0 to 900 nm is used, in this embodiment, since the image is written from the back side,
A shorter wavelength of 400 to 780 nm, which does not have sufficient transparency for the color toner, may be used. Further, since 80% or more of the image exposure light is absorbed by the photosensitive layer of the photosensitive drum 10, the influence of the reflection and absorption by the color toner on the surface of the photosensitive drum 10 can be neglected. Generally, the order of development of the color toner is preferably Y, M, C, and K from the relation of the color mixture to the toner image and the developing device 13. In FIG. 2, WA is a lead wire from a light emitting element (LED) for image exposure light.

Each developing unit 13 as a developing means contains a liquid developer composed of toner of each color of yellow (Y), magenta (M), cyan (C) and black (K) and a liquid carrier. Then, the rotation of the developing roller 13A causes the toner component in the developer to adhere to the photosensitive drum 10 side, thereby developing the latent image. As the liquid carrier, for example, isoparaffinic hydrocarbon such as Isopar (trade name) or silicon oil is used, and the developing roller 13A rotates in the same direction at a very small distance from the peripheral surface of the photosensitive drum 10. By applying a bias voltage, the toner in the carrier is electrophoresed and adheres to the latent image portion, and reversal development is performed.
A toner image is formed on the photosensitive drum 10.

In the present invention, a backside toner image is formed on the photosensitive drum 10, the backside toner image is transferred onto an intermediate transfer member by a transfer means, and a frontside toner image is formed again on the photosensitive drum. The front side toner image and the back side toner image are simultaneously transferred and fixed to both the front and back surfaces of the transfer material conveyed in synchronization.

The intermediate transfer belt 14, which is an intermediate transfer member, has a volume resistivity of 10 ⁸ to 10 ¹² Ω · cm, preferably 10 ¹⁰
In ~10 ¹¹ Ω · cm, a surface resistivity (unit: Ω / cm ²⁾ is an endless belt which is 1 to 100 times the value of the volume resistivity, for example modified polyimide, thermosetting polyimide, polyamide-imide, ethylene-tetra A conductive material is dispersed in an engineering plastic such as a fluoroethylene copolymer, polyvinylidene fluoride, or nylon alloy.
Outside the semiconductive film substrate having a thickness of 0.5 to 0.5 mm, preferably as a toner filming preventing layer having a thickness of 5 to 50 mm.
This is a seamless belt having a two-layer structure with a μm fluorine coating. As a base of the intermediate transfer belt 14,
In addition, a semiconductive rubber belt having a thickness of 0.3 to 2.0 mm in which a conductive material is dispersed in silicon rubber, urethane rubber, or the like can be used. The intermediate transfer belt 14 is
Each is stretched around a driving roller 14A, a transfer roller 14C, and a driven roller 14B, which are roller members, and is rotated at the same peripheral speed as the photosensitive drum 10 in a counterclockwise direction indicated by an arrow in FIG. The drive roller 14 </ b> A rotates by receiving drive from a drive motor (not shown), and drives and rotates the intermediate transfer belt 14. By the rotation of the intermediate transfer belt 14, the transfer roller 14C and the driven roller 14B are driven to rotate.

A transfer roller 14C, which is a transfer means, has a heater H built therein and is urged by an elastic member S, so that the intermediate transfer belt 14 is in contact with the photosensitive drum 10. It is also possible to apply a bias voltage, and the backside toner image formed on the photosensitive drum 10 is transferred to the transfer roller 14.
By applying a bias voltage having a polarity opposite to that of the toner to C, transfer is performed on the intermediate transfer belt 14. Note that when the transfer is performed by applying a pressure-bonding state without applying a bias voltage, the application of the bias voltage is omitted because of the adhesive force of the surface of the intermediate transfer belt 14 and the surface of the photosensitive drum 10 to the toner. can do. Further, by pressing and heating the transfer roller 14C with the recording paper P as a transfer material interposed therebetween, each toner image on the photosensitive drum 10 and the intermediate transfer belt 14 is simultaneously transferred to both front and back surfaces of the recording paper P. And it is fixed.

Next, the image forming process will be described. The photosensitive drum 10 is rotated clockwise as indicated by an arrow in FIG. 1 by the start of a photosensitive member drive motor (not shown) at the start of image recording, and at the same time, the yellow (Y) scorotron charger 1
The application of the potential to the photosensitive drum 10 is started by the charging operation of 1.

After the photosensitive drum 10 is applied with a potential, the Y exposure optical system 12 starts image writing with a first color signal, that is, an electric signal corresponding to the Y image data. An electrostatic latent image corresponding to the Y image of the original image is formed on the front surface.

The latent image is reversely developed by a Y developing device 13 to form a yellow (Y) toner image on the photosensitive drum 10.

Next, a potential is applied to the photosensitive drum 10 from above the Y toner image by the charging action of the magenta (M) scorotron charger 11, and the second color signal, that is, the M color signal, is applied by the M exposure optical system 12. Image writing is performed by an electric signal corresponding to the image data, and a magenta (M) toner image is formed on the yellow (Y) toner image by reversal development by the M developing unit 13. .

According to the same process, the cyan (C) toner image corresponding to the third color signal is further superimposed by the cyan (C) scorotron charger 11, the exposure optical system 12 of C, and the developing device 13 of C. The black (K) toner image corresponding to the fourth color signal is sequentially superimposed thereon by a black (K) scorotron charger 11, a K exposure optical system 12, and a K developing device 13. A superposed color toner image of four colors of yellow (Y), magenta (M), cyan (C) and black (K) is formed on the peripheral surface within one rotation of the photosensitive drum 10. .

These Y, M, C and K exposure optical systems 12
Image writing on the photosensitive layer of the photosensitive drum 10 is performed from the inside of the drum through the above-described translucent substrate. Therefore, the writing of the images corresponding to the second, third and fourth color signals is performed without any influence from the previously formed toner image, and is equivalent to the image corresponding to the first color signal. Can be formed.

In the transfer area 140, the superimposed color toner image serving as the back surface image formed on the photosensitive drum 10 as the image forming body by the image forming process is formed.
By applying a bias voltage having a polarity opposite to that of the toner to the transfer roller 14C, the toner image is collectively transferred onto the intermediate transfer belt 14, which is an intermediate transfer member.

After the superimposed color toner image serving as the back surface image is formed on the intermediate transfer belt 14a as described above, the front surface image is continuously formed on the photosensitive drum 10 in the same manner as the above color image forming process. Is formed (FIG. 3). At this time, the image data is changed so that the front surface image formed on the photosensitive drum 10 is a mirror image of the rear surface image formed on the photosensitive drum 10.

With the formation of a surface image on the photosensitive drum 10, a recording paper P as a transfer material is carried out from a paper feed cassette 15 as a transfer material storage means by an operation of a carry-out roller 16, and is sent out by a carry roller 17. The toner image is conveyed to a timing roller 18 serving as a transfer material feeding unit. The driving of the timing roller 18 causes the color toner image of the front surface image formed on the photosensitive drum 10 and the back surface carried on the intermediate transfer belt 14. The image is fed to the transfer area 140 in synchronization with the color toner image.

The recording paper P is sandwiched between the peripheral surfaces of the photosensitive drum 10 and the intermediate transfer belt 14 in the transfer area 140 and is heated by the heater H of the transfer roller 14C and pressurized by the elastic member S. Has a photosensitive drum 1
The color toner image of the front surface image on the zero peripheral surface and the color toner of the back surface image on the peripheral surface of the intermediate transfer belt 14 are simultaneously transferred and fixed on the lower surface.

The intermediate transfer belt 14 is different from a drum-shaped transfer body in that it has a large degree of freedom in installation space, which is advantageous for compactness of the apparatus. Is fixed by the transfer roller 14C, the separation from the belt surface after the fixing is easy, and the sheet advances straight in the horizontal direction without fail and is discharged to the tray 20 via the discharge roller 19.

As described above, the double-sided image forming apparatus of the present invention described with reference to the first embodiment has high image quality because the toner image visualized by the liquid developer is efficiently transferred by pressing. In addition, since the fixing is performed at a relatively low temperature, the paper quality of the transfer material is not impaired, and ozone generated by corona discharge of the transfer unit in the double-sided image forming apparatus and excessive heat exhausted from the fixing unit that performs high-temperature heat fixing are used. It has excellent advantages such as no action required.

(Embodiment 1) The first embodiment of the double-sided image forming apparatus of the present invention has already been described with reference to FIGS. Next, a second embodiment will be described with reference to a sectional view shown in FIG. In the first embodiment, the photosensitive drum 1
0, a back toner image is formed on the intermediate transfer belt, and then a front toner image is formed on the same photosensitive drum 10, and the front toner image and the back toner image are simultaneously transferred to the front and back surfaces of the recording paper P. Although the fixing is performed, the second embodiment is a tandem-type double-sided image forming apparatus including two image forming members, that is, a photosensitive drum 10A and a photosensitive drum 10B.
Since the photosensitive drum 10 in the first embodiment and the photosensitive drums 10A and 10B in the second embodiment perform charging, image exposure, and development with exactly the same configuration to form a color toner image, Detailed description is omitted. Members having the same function are denoted by the same reference numerals.

In forming an image, the intermediate transfer belt 1
A color toner image on the back surface of the document is formed on the peripheral surface of the photoconductor drum 10A located on the upstream side of the conveyance of No. 4. On the other hand, the color toner image on the surface of the original is
0B, respectively. The tandem-type double-sided image forming apparatus can form the toner images on the front and back sides of the original partially in a partially overlapping manner, so that the copying time can be greatly reduced as compared with the double-sided image forming apparatus of the first embodiment. There is.

The color toner image formed on the back surface of the original formed on the photosensitive drum 10A is applied to the transfer roller 14D pressed against the photosensitive drum 10A with the intermediate transfer belt 14 therebetween by applying a bias voltage having a polarity opposite to that of the toner. Alternatively, the transfer of the color toner image on the back surface is started on the intermediate transfer belt 14 by utilizing the difference in temperature and the difference in adhesive strength, and the document is placed on the photosensitive drum 10B slightly later than the original on the photosensitive drum 10B according to a preset time. The formation of the color toner image on the surface is started.

At the same time, the recording paper P is unloaded from the paper feed cassette 15 by the operation of the unloading roller 16, temporarily stopped at the timing roller 18 via the transport roller 17, and waits. The recording paper P is fed to the transfer area 140 on the intermediate transfer belt 14 at a timing such that the leading edge of the toner image matches the leading edge of the recording paper P.

In the image transfer area 140, the photosensitive drum 10B is pressed by the transfer roller 14C and transferred and fixed by heating in the same manner as in the first embodiment.
The recording paper P sandwiched between the intermediate transfer belt 14 and the intermediate transfer belt 14 records a color toner image on both front and back surfaces, and is discharged to a tray 20 via a discharge roller 19.

(Embodiment 2) FIG. 4 is a sectional view showing a third embodiment of the double-sided image forming apparatus of the present invention. The difference of the present embodiment from the first embodiment is that
The intermediate transfer belts 14a and 14b are provided, and the front and back color toner images formed on the photosensitive drum 10 are transferred and held on the intermediate transfer belts 14a and 14b, respectively, so that the color images on the intermediate transfer belts 14a and 14b are transferred. The toner image is transferred and fixed on the front and back of the recording paper P at once.
Formation of the Color Toner Image of Example 3 and Transfer and Transfer of the Image
The fixing process is performed as follows.

In forming an image, first, a color toner image of the back side image is formed on the photosensitive drum 10 based on the data of the back side image. The color toner image on the back surface of the document formed on the photosensitive drum 10 is transferred to the upper intermediate transfer belt by applying a bias voltage having a polarity opposite to that of the toner to the transfer roller 14D pressing the photosensitive drum 10 from behind the intermediate transfer belt 14a. The color toner image on the back surface of the upper intermediate transfer belt 14a is transferred to a transfer roller 14C provided in the lower intermediate transfer belt 14b by applying a bias voltage having a polarity opposite to that of the toner. The image is transferred onto the intermediate transfer belt 14b and temporarily held. The transfer of the toner on the upper intermediate transfer belt 14a to the lower intermediate transfer belt 14b is performed by applying the adhesive force between the toner on the intermediate transfer belt 14b and the toner in addition to the application of the bias voltage. When the value is larger than that, the transfer of the toner image is performed. Further, the temperature T ₂ of the lower intermediate transfer belt 14 b is
The toner image can also be transferred from the intermediate transfer belt 14a to the intermediate transfer belt 14b by setting T ₂ <T ₁ with respect to the temperature T _{1 of} a. The above transfer means may be used in combination for transfer.

Next, a color toner image on the front surface of the document is formed on the photosensitive drum 10 at a preset time, and the position is synchronized with the color toner image on the back surface of the intermediate transfer belt 14b. The color toner image on the upper surface is transferred onto the intermediate transfer belt 14a by applying a bias voltage having a polarity opposite to that of the toner to the transfer roller 14D.

At the same time, the recording paper P is carried out of the paper feed cassette 15 and transferred via the timing roller 18 so as to synchronize the positions with the respective color toner images on the front surface on the intermediate transfer belt 14a and the back surface on the intermediate transfer belt 14b. Paper is fed to the area 140.

In the transfer area 140, the recording paper P is sandwiched between the respective peripheral surfaces of the intermediate transfer belts 14a and 14b, and is heated by the heaters H of the upper and lower transfer rollers 14C and applied to the lower transfer roller 14C by the elastic member S. Due to the pressure, the color toner image of the front surface image of the peripheral surface of the intermediate transfer belt 14a is simultaneously transferred and fixed on the upper surface, while the color toner image of the rear surface image of the peripheral surface of the intermediate transfer belt 14b is transferred and fixed on the lower surface.

In the transfer of the color toner image to the recording paper P, the transfer of the toner image is performed efficiently due to the adhesive force of the recording paper which is larger than the toner adhering portion to the toner and the temperature difference with respect to the transfer roller 14C. Nothing to do. When the transfer of the back side color toner image to the lower intermediate transfer belt 14b is performed by using the temperature difference between the upper and lower belts, the transfer of the heater H of the lower transfer roller 14C to the recording paper P is performed. temperature T ₁ of the heater H of the temperature T ₂ is the upper transfer roller 14C equivalent (T ₁
= T ₂ ).

The temperature of the built-in heater H of each of the transfer rollers 14C is relatively low (50 to 80 ° C.), and furthermore, as is clear from the drawing, the heater H is set apart from the peripheral surface of the photosensitive drum 10. Therefore, the deterioration of the characteristics of the photoreceptor due to the high heat is prevented, and the performance of the photoreceptor is maintained, so that a high quality toner image is always formed.

(Embodiment 3) The process of image transfer and fixing by the double-sided image forming apparatus of Embodiment 4 will be described with reference to FIG.

The double-sided image forming apparatus shown in this embodiment uses a belt-shaped photoreceptor as an image forming body, and transfers images on the front and back of a document formed on the belt directly onto a transfer material via an intermediate transfer body. This is a fixing type double-sided image forming apparatus.

The flexible photoreceptor belt 110 is stretched between a driving roller 110A and a driven roller 110B, and is conveyed and rotated clockwise by the power transmitted to the driving roller 110A. The image forming units including the exposure optical system 12 and the developing device 13 are arranged in the order of yellow (Y), magenta (M), cyan (C), and black (K) from the upstream side of the belt.

The color toner images on the back and front sides of the document formed on the photosensitive belt 110 by the respective image forming units are transferred and fixed in exactly the same manner as in the double-sided image forming apparatus of the first embodiment described above. Are recorded on the upper and lower surfaces of the recording paper P, respectively.

Since the belt-shaped photoconductor can take a free form different from the drum-shaped photoconductor, the radius of curvature of the photoconductor belt 110 in the transfer area 140 can be set small, and the recording after transfer and fixing is completed. Separated conveyance of paper can be ensured. Further, as shown in the figure, the layout of the apparatus can be freely adjusted such that the floor area occupied by the apparatus is small when the image forming surface is in the vertical position, or the apparatus is short in height in the horizontal position.

[0051]

According to the present invention, there is provided a double-sided image forming apparatus capable of recording a high-quality image by efficient transfer and fixing without generating ozone or high heat according to the first aspect. According to the second aspect, the apparatus can be made compact, the third aspect speeds up image recording, the fourth aspect maintains the characteristics of the image forming member, and the fifth aspect allows the apparatus to be freely configured. This realizes a double-sided image forming apparatus capable of performing the following.

[Brief description of the drawings]

FIG. 1 is a sectional configuration diagram of a double-sided image forming apparatus using a belt-shaped intermediate transfer member.

FIG. 2 is a side sectional view of the image forming body.

FIG. 3 is a cross-sectional configuration diagram of a double-sided image forming apparatus using a plurality of image forming bodies.

FIG. 4 is a sectional configuration diagram of a double-sided image forming apparatus using a plurality of intermediate transfer members.

FIG. 5 is a cross-sectional configuration diagram of a double-sided image forming apparatus using a belt-shaped image forming body.

[Explanation of symbols]

 Reference Signs List 10 photoconductor drum 11 scorotron charger 12 exposure optical system 13 developing device 13A developing roller 14, 14a, 14b intermediate transfer belt 14A drive roller 14C, 14D transfer roller 15 paper feed cassette 18 timing roller 19 paper discharge roller 20 tray 21 manual feed Paper board 22 Manual feed roller 110 Photoreceptor belt 140 (Image) transfer area H Heater S Elastic member P Recording paper

Claims (5)

[Claims] 1. A double-sided image forming apparatus for transferring and fixing a toner image formed on an image forming body to both front and back surfaces of a transfer material via an intermediate transfer body, wherein the toner images on both front and back sides are located at the same location from both sides. A double-sided image forming apparatus wherein the image is transferred and fixed on a transfer material by heating and pressing. 2. The double-sided image forming apparatus according to claim 1, wherein the intermediate transfer member is a belt-shaped intermediate transfer member. 3. The double-sided image forming apparatus according to claim 1, wherein the image forming body is a plurality of image forming bodies. 4. The double-sided image forming apparatus according to claim 1, wherein both of the toner images on both the front and back sides are temporarily transferred to an intermediate transfer member. 5. The double-sided image forming apparatus according to claim 1, wherein the image forming body is a belt-shaped image forming body.