JPH1115305A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device of a high speed and a low energy consumption, by which a picture of high quality can be recorded on both sides. SOLUTION: An image forming device 1, equipped with image carriers, 10a to 10d, an intermediate transferrer 14, corotron transcribers 16a to 16d, pressure rollers 17a and 17b, and tungsten halogen lamps, 18a and 18b, is provided by installing a far-infrared ray heater 15a, which heats a part of the intermediate transferrer 14 in more upstream part of a moving direction of the intermediate transfer 14 than the pressure rollers 17a and 17b, up to a higher temperature than a heating temperature of the pressure rollers 17a and 17b, by the tungsten halogen lamps 18a and 18b.

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 used for an electrophotographic printer or copier.

[0002]

2. Description of the Related Art In a conventional electrophotographic image forming apparatus, for example, an electrostatic latent image is formed on an image carrier, developed with dry toner to form a toner image, and then the toner image is recorded on a recording medium. In an image forming apparatus that obtains an image by electrostatically transferring and fixing the image, unevenness in the density of the image or scattering of the powder toner occurs, thereby deteriorating the resolution and dot reproducibility of the image. May cause problems. Such uneven density and toner scattering mainly occur during the process of electrostatically transferring a toner image on an image carrier to a recording medium.

[0003] In the electrostatic transfer system, the toner transfer efficiency increases in proportion to the strength of the electric field applied to the toner layer. Efficiency starts to decrease.
That is, the transfer efficiency shows a peak value at a certain electric field intensity. Generally, the peak value of the transfer efficiency does not reach 100%, and often remains at about 95% at the maximum.

As described above, since the transfer efficiency of the toner layer depends on the strength of the electric field, the strength of the electric field is affected by unevenness of the thickness of the toner layer, surface properties such as unevenness of a recording medium such as paper, and unevenness of electric properties. The transfer efficiency fluctuates with the fluctuation. When the toner image formed on the recording medium is monochromatic and the layer thickness is small, the strength of the electric field fluctuates mainly due to the surface properties such as unevenness of the recording medium or the unevenness of electric properties, and as a result, image unevenness occurs. I do. Similarly, when a single color toner image independently formed on an image carrier is overlaid and transferred onto a recording medium to form a color image, image unevenness is similarly caused by surface properties such as unevenness of the recording medium or uneven electrical properties. Occur. In the electrostatic transfer method, transfer efficiency is caused by a change in layer thickness between a high-layer portion formed by superimposing and transferring a plurality of toner images and a low-layer portion formed by transferring a single-color toner image. Although the difference is small, the transfer efficiency varies greatly due to surface properties such as unevenness of the recording medium or unevenness in electrical properties, and image unevenness is likely to occur.

On the other hand, a plurality of toner images independently formed on an image carrier are electrostatically primary-transferred so as to be sequentially superimposed on an intermediate transfer body having less unevenness in surface properties and electric properties. Then, in a so-called intermediate transfer type color image forming apparatus in which a multicolor toner image formed on an intermediate transfer member is secondarily transferred to a recording medium, an image with less image unevenness can be obtained because of little change in transfer efficiency. it can.

In order to uniformly transfer a toner image onto a recording medium such as paper electrostatically, it is necessary to apply a constant electric field. However, a multicolor toner image formed on an intermediate transfer member is frequently used. Indicates that three or more layers of toner images are formed,
Since a single layer toner image is not formed in a small area, it is difficult to apply a constant electric field to the toner image having such a large change in layer thickness, and the electric field strength is not uniform. Therefore, in the secondary transfer by the electrostatic transfer method,
All of the multicolor toner images formed on the intermediate transfer member may not be transferred to the recording medium but may partially remain on the intermediate transfer member. Since the amount of toner remaining on the intermediate transfer member varies depending on the thickness of the toner layer on the intermediate transfer member, the color balance of the color image obtained on the recording medium is lost, and it is difficult to obtain a desired color image. In addition, the recording medium and the intermediate transfer body do not completely adhere to each other due to the unevenness of the surface of the recording medium, and the transfer electric field is disturbed by an uneven gap generated between the two, and the Coulomb repulsion between toners. In some cases, the transfer efficiency is reduced by the force and the image quality is deteriorated.

As a solution to such a problem, Japanese Patent Publication No. 46-41679 discloses a method in which a toner image formed on an image carrier is adhesively transferred to an elastic intermediate transfer member surface, and then a heating roller is used. There is disclosed an image forming method in which a recording medium supplied between an intermediate transfer member and a heating roller is heated to melt a toner image on the intermediate transfer member and thermally transfer the toner image onto the recording medium. In addition, Japanese Patent Publication No. 64-1024,
In Japanese Patent Publication No. 64-1027, an intermediate transfer body and a recording medium, which are superposed with a toner image transferred on an endless belt-shaped intermediate transfer body therebetween, are pressed against each other with a heating roll and a pressure roll. A method of transferring and fixing a toner image on an intermediate transfer member onto a recording medium is disclosed. JP-B-57-20632, JP-B-58-36341 and JP-B-64-1023 disclose that a toner image transferred onto an endless belt-shaped intermediate transfer member is heated to a temperature higher than the melting point of the toner. Then, when the intermediate transfer body and the recording medium are pressed against each other and the toner image on the intermediate transfer body is transferred and fixed onto the recording medium, the intermediate transfer body and the recording medium are pressed against each other, and then the intermediate transfer body and the recording medium are pressed. Is circulated and moved for a long period of time, and by sufficiently transferring heat from the intermediate transfer body to the recording medium during this contact state, the toner on the intermediate transfer body is transferred and fixed to the recording medium. A method of ensuring is disclosed.

[0008] In these non-electrostatic transfer systems, there is no trouble caused by the non-uniformity of the electric field as in the above-mentioned electrostatic transfer system, so that a color image having high transfer efficiency and high sharpness is obtained. , A high-quality image with good color balance can be obtained. However, Shoko 4
No. 6-41679, Japanese Patent Publication No. 64-1024,
In the method disclosed in Japanese Patent Publication No. 64-1027, the pressure roll disposed on the back side of the recording medium is not provided with a heating means, so that the recording medium takes a large amount of heat to record the toner image. There is a problem that the toner on the side in contact with the medium is not easily fused to the recording medium, and a fixing failure is likely to occur particularly when performing image formation at high speed.

Further, Japanese Patent Publication No. 57-20632, Japanese Patent Publication No. 58-36341, and Japanese Patent Publication No. 64-10
In the method disclosed in Japanese Patent Publication No. 23, while the intermediate transfer body and the recording medium are moving in contact with each other for a long time, the intermediate transfer body and the recording medium may be displaced from each other. There is a problem that the pressing force between the intermediate transfer body and the recording medium becomes non-uniform and image disorder occurs.

In addition to these methods, Japanese Patent Publication No. 3-6375
No. 6, Japanese Patent Publication No. 3-63757, and Japanese Patent Publication No. 3-63758 disclose that an intermediate transfer body carrying a toner image and a recording medium are pressed by a pair of pressure rolls on the intermediate transfer body. In an image forming apparatus that transfers and fixes a toner image on a recording medium, a transfer fixing device that preheats the recording medium upstream of the transfer fixing area is provided separately from the pair of pressure rolls to enable high-speed fixing. A method is disclosed. Of the transfer fixing methods using the preheating heater disclosed in these three publications, Japanese Patent Publication No. 3-637
In the method disclosed in Japanese Patent Application Publication No. 56-56, a toner image on an intermediate transfer body is heated to a temperature lower than the melting temperature of the toner, and a pressing roll heated to a temperature higher than the melting temperature of the toner is pressed against the intermediate transfer body. The toner image is transferred and fixed to the recording medium by feeding the recording medium heated to a temperature higher than the melting temperature of the toner into the recording medium. In addition, the method disclosed in Japanese Patent Publication No. 3-63757 discloses
Unlike the method disclosed in Japanese Patent Publication No. 3-63756, the toner image on the intermediate transfer member is heated to a temperature lower than the melting temperature of the toner, and the pressing roll heated to a temperature lower than the melting temperature of the toner is transferred to the intermediate transfer member. Then, a recording medium heated to a temperature equal to or higher than the melting temperature of the toner is sent to the pressure contact portion to transfer and fix the toner image on the recording medium. Further, the method disclosed in Japanese Patent Publication No. 3-63758 is different from the method disclosed in Japanese Patent Publication No. 3-63756 and the method disclosed in Japanese Patent Publication No. 3-63757 in that the toner image on the intermediate transfer member is formed by toner. By heating to a temperature lower than the melting temperature, pressing the press roll heated to a temperature higher than the melting temperature of the toner against the intermediate transfer member, and feeding the recording medium heated to a temperature lower than the melting temperature of the toner into the pressed portion This is a method of transferring and fixing a toner image to a recording medium.

In the transfer fixing method using the preheating heater disclosed in these three publications, it is possible to suppress excessive heating of the pressure roll, so that the thermal efficiency can be improved, and There is an advantage that it is possible to prevent the occurrence of defective fixing due to the offset phenomenon or the like caused by the heating.

[0012]

Incidentally, image forming apparatuses such as copiers and printers are often required to have a function of recording images on both sides of a recording medium. It is necessary to configure the image forming apparatus so that an image can be recorded on the second surface after the image formation.

However, Japanese Patent Publication No. 3-63756, Japanese Patent Publication No. 3-63757, and Japanese Patent Publication No. 3-6375.
When double-sided recording is performed by an image forming apparatus employing the transfer and fixing method disclosed in Japanese Patent Application Laid-Open No. 8-208, the following problem may occur. That is, in the method disclosed in Japanese Patent Publication No. 3-63756 and Japanese Patent Publication No. 3-63758, the pressing roll that is pressed against the intermediate transfer member is heated to a temperature equal to or higher than the melting temperature of the toner. After performing image recording on one side, when the recording medium is reversed and image recording is performed on the second side, the toner of the image recorded on the first side is re-melted by the heat of the pressing roll, deteriorating the image quality May cause Further, in the method disclosed in Japanese Patent Publication No. 3-63757, the recording medium is heated by the preheating heater to a temperature higher than the toner melting temperature. When image recording is performed on the second surface by reversing the above, the toner of the image recorded on the first surface may be heated from the back side by the preheating heater and re-melted, thereby deteriorating the image quality.

Therefore, any of the transfer fixing methods using the preheating heater disclosed in the above three publications is not suitable for an image forming apparatus that performs double-sided recording. In the transfer fixing method using the preheating heater, when paper is used as a recording medium, the paper heated by the preheating heater undulates with heat, and a jam occurs at the pressure roll nip. There is. In addition, since the water contained in the paper is vaporized at the stage of the preheating, there is a problem that the thermal efficiency is reduced.

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide a high-speed, low-energy image forming apparatus capable of recording high-quality images on both sides.

[0016]

In order to achieve the above object, an image forming apparatus according to the present invention comprises an image carrier on which a toner image is formed, and moves while approaching or in contact with the image carrier.
An intermediate transfer member on which the toner image formed on the image carrier is transferred, transfer means for transferring the toner image formed on the image carrier onto the intermediate transfer member, and a toner image transferred by the transfer means A predetermined recording medium is superimposed on the intermediate transfer body with the toner image on the intermediate transfer body interposed therebetween, and pressure is applied with the superimposed intermediate transfer body, toner image, and recording medium interposed therebetween. In an image forming apparatus including a pair of pressing members and a pressing member heating unit that heats the pressing members, a portion of the intermediate transfer member upstream of the pressing member in the moving direction of the intermediate transfer member. And an intermediate transfer member heating means for heating the heating member to a temperature higher than the heating temperature of the pressing member by the pressing member heating means.

[0017]

Embodiments of the present invention will be described below. FIG. 1 is a schematic configuration diagram of a first embodiment of the image forming apparatus of the present invention. This image forming apparatus 1 is an application of the present invention to a color copying machine capable of recording an image on both sides of a recording medium by a simultaneous transfer and fixing method using an intermediate transfer member.

In the image forming apparatus 1 shown in FIG. 1, electrostatic latent images corresponding to respective colors of black, yellow, magenta and cyan are formed on the surface, and image carriers 10a and 10b which rotate in the direction of arrow A respectively. , 10c, 10d, primary chargers 12a, 12b, 12c, 12d for uniformly charging these image carriers 10a, 10b, 10c, 10d, and exposure light corresponding to the image of each color on the surface of each image carrier. And an optical scanning device 13 that forms an electrostatic latent image on each image carrier by irradiating the electrostatic latent images formed on the image carriers 10a, 10b, 10c, and 10d with the above-described color toners. Developing device 11 for forming toner images corresponding to each of the above colors
a, 11b, 11c, 11d, a belt-shaped intermediate transfer member 14 circulating in the direction of arrow B to which the toner image formed on each image carrier is transferred, and an intermediate transfer member for transferring the toner image on each image carrier. Corotron transfer devices 16a, 16b, 16c, and 16d for electrostatically transferring the toner images so as to be superimposed on each other, and in a predetermined heating / pressing region T2, the toner images of the respective colors that are superimposed and transferred on the intermediate transfer body 14 are interposed therebetween. A pair of pressure rolls 17a, 17b for pressing the intermediate transfer body 14 on the recording medium P so as to sandwich the intermediate transfer body 14, and a halogen lamp for heating the pressure rolls 17a, 17b disposed in the pressure rolls 17a, 17b from the inside. 18a, 18b, pressure rolls 17a, 1
7b and a support roll 19 for supporting the intermediate transfer body 14
a, 19b, 19c, and 19d, a far-infrared heater 15a for heating the intermediate transfer member 14 disposed upstream of the heating and pressing region T2, and the intermediate transfer member 1 after passing through the heating and pressing region T2.
A cooling device 20 for cooling the toner image sandwiched between the recording medium P and the recording medium P, and a tray 21 for storing the recording medium P are provided.

The image forming apparatus 1 has two operation modes, a double-sided recording mode for recording an image on both sides of a recording medium and a single-sided recording mode for recording an image on only one side of the recording medium. Is provided with a recording medium reversing device 30 which is used when the double-sided recording mode is set. The recording medium reversing device 30 includes transport direction switches 31 and 3
2. Recording medium reversing unit 33 and recording medium transport roll 3
4, 35a, 35b, 35c, 35d, 35e, etc. In this image forming apparatus 1, at the start of image formation,
The operation mode is set to either the double-sided recording mode or the single-sided recording mode based on a control signal included in an image signal input to the image forming apparatus 1 or based on an operation of an operator of the image forming apparatus 1. Recording medium reversing device 3
The operation of 0 will be described later.

The corotron transfer units 16a, 16b, 16c and 16d in this embodiment correspond to the transfer means according to the present invention, and include the pressure rolls 17a and 17b.
Corresponds to the pressing member according to the present invention, the halogen lamps 18a and 18b correspond to the pressing member heating means according to the present invention, and the far infrared heater 15a corresponds to the intermediate transfer member according to the present invention. It corresponds to a heating means.

The image carriers 10a, 10 in this embodiment
As b, 10c, and 10d, Se, a-Si, a-S
Inorganic photoconductors such as iC and CdS, and various organic photoconductors can be used. As the toner, a toner composed of a thermoplastic binder containing a dye such as black, yellow, magenta, and cyan can be used.

The intermediate transfer member 14 has a two-layer structure including a base layer and a surface layer. As the base layer, a polyimide film having a thickness of 70 μm to which carbon black is added is used. The volume resistivity of the base layer is adjusted to 10 ¹⁰ Ω · cm by adjusting the amount of carbon black added so that the toner image on the image carrier is electrostatically transferred to the intermediate transfer member without image disturbance. Is set to As the base layer, a high heat-resistant sheet having a thickness of 10 to 300 μm, for example, a polymer sheet of polyester, polyethylene terephthalate, polyethersulfone, polyetherketone, polysulfone, polyimide, polyimideamide, polyamide, or the like may be used. Good. As the surface layer, when performing simultaneous transfer and fixing from the intermediate transfer member 14 to the recording medium P, a rubber hardness is set to improve the adhesion between the intermediate transfer member 14 and the recording medium P with the toner image interposed therebetween. A silicone copolymer having a thickness of 40 degrees and a thickness of 50 μm is used. The silicone copolymer has elasticity and its surface is sticky to the toner at room temperature. This is the most suitable layer material. The volume resistivity of the surface layer is set to 10 ¹⁴ Ω · cm so that the toner image on the image carrier is electrostatically transferred to the intermediate transfer member without image disturbance. As the surface layer, a resin having a high releasability having a thickness of 1 to 100 μm, for example, a tetrafluoroethylene-perfluoroalkylvinyl ether copolymer, polytetrafluoroethylene, or the like may be used.

As the pressure rolls 17a and 17b, those having a heat-resistant elastic layer such as silicone rubber on a metal roll can be used. In the present embodiment, the pressure roll 1
7a, a 50 mm hardness silicone rubber was coated on an aluminum hollow roll with a thickness of 0.5 mm to form an outer diameter of 50 m.
As the pressure roll 17b, an aluminum hollow roll coated with silicone rubber having a hardness of 50 degrees and having a thickness of 3.0 mm and having an outer diameter of 50 mm is used. The nip pressure by the pressure rolls 17a and 17b is set to 5.5 × 10 ⁵ Pa. The nip width is approximately 6 mm.

The pressing member is the above-described pressing roll 17.
a, 17b is not limited to only the configuration,
Any configuration may be used as long as it can uniformly pressurize the intermediate transfer member 14 and the recording medium P without causing lifting or displacement. For example, a configuration in which one pressure roll and one fixing pad are combined, or a set of fixing pads may be used.

In this embodiment, the pressure rolls 17a, 17
The halogen lamps 18a and 18b are arranged as heat sources inside b. However, the heat source of the pressing member is not limited to the halogen lamp, and any other heating means may be used. As the intermediate transfer body heating means, a far infrared heater 1
5a is used. The far-infrared heater 15a is arranged upstream of the heating / pressurizing region T2, and heats the surface of the intermediate transfer member 14 on which the toner image is formed by radiant heat in a non-contact manner. By using a non-contact heater as the intermediate transfer body heating means in this way, the toner image can be formed without applying a load to the movement of the intermediate transfer body 14 and without mechanically disturbing the toner image. It can be fused and fused. Further, since the surface of the intermediate transfer member 14 on which the toner image is formed can be directly heated by radiant heat, the fusion and fusion of the toner can be ensured, and the toner image can be transferred and fixed at high speed without causing an offset phenomenon. Can be. In particular, in the case of a color image forming apparatus, it is preferable to use a far-infrared heater in order to avoid the occurrence of heating unevenness due to the difference in the light absorption characteristics of each color toner.

Next, an image forming process by the image forming apparatus 1 of the present embodiment will be described with reference to FIG. In the present embodiment, a toner having a melting temperature of 115 ° C. is used, the intermediate transfer body 14 is circulated at a moving speed of 160 mm / s, and 40 high-speed images are formed on A4 size recording paper per minute. Note that the toner melting temperature in the present embodiment is a flow tester CFT- manufactured by Shimadzu Corporation.
The value measured by Model 500 is used as a reference. That is, after 1.5 g of toner is molded by a pressure molding machine,
The molded toner is put into a flow tester CFT-500, and the load is 98 N (10 kgf) and the nozzle diameter is 0.5 m.
m, the nozzle length is 1 mm, the toner is extruded from the nozzle while the temperature is raised from 60 ° C. to 150 ° C. at a rate of 5 ° C./min, and the outflow amount of the toner is measured at every 3 ° C., and the apparent viscosity η ′ (poise) ) And apparent viscosity η ′ is 10
^The temperature at which the temperature becomes ⁴ poise is defined as the toner melting temperature.

As recording paper, J paper manufactured by Fuji Xerox Co., Ltd. is used. First, the primary charger 12
a, the surface of the image carrier 10a is uniformly charged, and then the exposure light corresponding to the black image is irradiated by the optical scanning device 13 to form an electrostatic latent image corresponding to the black image on the image carrier 10a. After that, the black developing device 11a develops black, and a black toner image is formed on the image carrier 10a. The black toner image is conveyed to the primary transfer position T1 of the image carrier 10a where the image carrier 10a is in contact with the intermediate transfer belt 14 by the rotation of the image carrier 10a, and the primary transfer position T1 of the image carrier 10a.
Is primary-electrostatically transferred onto the intermediate transfer belt 14 by the corotron transfer unit 16a. On the other hand, yellow, magenta and cyan toner images are formed on the image carriers 10b and 10b.
c, 10d are sequentially formed, and the toner images of each color are electrostatically and primarily transferred onto the intermediate transfer belt 14 sequentially by the corotron transfer units 16b, 16c, 16d, and the multicolor toner image is transferred onto the intermediate transfer transfer belt 14. Is formed.

The multicolor toner image formed on the intermediate transfer belt 14 is a far-infrared heater 15a disposed on the upstream side in the moving direction B of the intermediate transfer belt 14 with respect to the heating and pressing area T2.
Is heated. The heating temperature of the intermediate transfer body 14 by the far-infrared heater 15a is about 165 ° C. This temperature was measured by measuring the surface temperature of the intermediate transfer member 14 at the position of the pressure roll 17b on the toner image carrying surface side.

The recording medium P sent from the tray 21 is supplied to the heating and pressing area T2 at the timing when the multicolor toner image carried on the intermediate transfer belt 14 reaches the heating and pressing area T2. . The pressure rolls 17a and 17b press against each other as the recording medium P is fed to form a nip. Intermediate transfer belt 14, multicolor toner image,
The recording medium P is heated and pressurized in the heating and pressurizing region T2. The pressure roll 17a is a halogen lamp 1
8a, the temperature is controlled to 120 ° C.
The temperature b is controlled to 100 ° C. by the halogen lamp 18b. The multi-color toner image is heated and softened and melted by the pressure rolls 17a and 17b, penetrates into the recording medium P, and then is aggregated and solidified to perform transfer fixing.

The recording medium P moves toward the support roll 19c while keeping the toner image in close contact with the intermediate transfer belt 14, and is cooled by the cooling device 20 during the movement. In this process, the toner image is coagulated and solidified, and a strong adhesive force with the recording medium P is generated. The adhesion strength of the toner image to the recording medium P gradually becomes stronger than the adhesion strength to the intermediate transfer belt 14, and the toner image is gradually fixed on the recording medium P.
Thereafter, the recording medium P reaches the portion of the support roll 19c having a small curvature, and is separated from the intermediate transfer belt 14 together with the toner image by the stiffness of the recording medium itself. The surface of the toner image transferred and fixed to the recording medium P follows the surface of the intermediate transfer member 14 and is smoothed to have a high gloss.

Thus, the recording medium P on which the image is recorded on the first surface of the recording medium P and which is separated from the support roll 19c is
Two types of operations are performed according to the operation mode set at the start of image formation. That is, when the single-sided recording mode is set, the transport direction of the recording medium P is switched to the direction toward the recording medium discharge port 36 by the transport direction switching member 31 so that the recording medium on which the image is recorded on the first surface is set. P is discharged from the recording medium discharge port 36 to the outside of the apparatus.

On the other hand, when the double-sided recording mode is set, the transport direction of the recording medium P is switched by the transport direction switching member 31 to the direction toward the recording medium reversing section 33, so that the image is displayed on the first surface of the recording medium. Is recorded on the recording medium P by the recording medium transport roll 34.
3 is carried. Next, the recording medium P is conveyed in the reverse direction by the recording medium conveyance roll 35a, and the conveyance direction switch 32
The transport direction is switched to the direction facing the recording medium transport roll 35b by the, and the recording medium transport rolls 35b, 35c, 3
By 5d and 35e, it is conveyed to the heating and pressurizing area T2. In the heating and pressurizing region T2, transfer and fixing of the toner image to the second surface of the recording medium P are performed. After the recording medium P on which the images are recorded on both sides is cooled by the cooling device 20, the recording medium P reaches the portion of the support roll 19c, and the recording medium P
From the sheet together with the toner image. Here, the transport direction switch 31 changes the transport direction of the recording medium P to the recording medium outlet 3.
6, the recording medium P is discharged from the recording medium discharge port 36 to the outside of the apparatus.

When the double-sided recording mode is set,
In this way, an image is sequentially recorded on the first surface and the second surface of the recording medium, but if the temperature of the intermediate transfer body during image recording on the second surface is not properly controlled, an offset phenomenon may occur or an image may be generated. Disturbance may occur. In the simultaneous transfer and fixing method, the toner image is heated to fuse the toners constituting the image and all the toner on the intermediate transfer body is transferred to the recording medium. If the fusion is incomplete, the transfer and fixing failure, that is, the so-called offset phenomenon is likely to occur. If the toner image is heated too much and the toner is heated excessively, the toner may flow and cause image disturbance. In particular, when the toner is excessively heated in the vicinity of the press-contact portion between the intermediate transfer body and the recording medium and the vicinity thereof, surface irregularities of the recording medium such as paper may cause
In a portion where the adhesion between the recording medium and the intermediate transfer member is poor, the toner may flow by capillary flow, which may cause deterioration in image quality.

Therefore, in the image forming apparatus 1 of the present embodiment, the pressure rolls 17a and 17b of the intermediate transfer body 14
The portions of the intermediate transfer member 14 on the upstream side in the moving direction of the intermediate transfer member 14 are pressurized by rolls 17a, 17 by halogen lamps 18a, 18b.
b, a far-infrared heater 15a for heating the intermediate transfer member 14 to a temperature higher than the heating temperature of the intermediate transfer member 14 before being pressed against the recording medium P.
Is heated to a temperature higher than the heating temperature of the pressure rolls 17a and 17b. This facilitates the melting of the toner image on the intermediate transfer member 14 after being pressed against the recording medium P, and the fused toner can be fused to the recording medium P.

Further, by setting the heating temperature of the pressure rolls 17a, 17b by the halogen lamps 18a, 18b lower than the temperature of the intermediate transfer body 14 before pressing, the image on the second side in the double-sided recording mode is set. It is possible to prevent the toner image from being melted and fluidized on the back side (the image has already been recorded by the image formation on the first side) in the formation, thereby avoiding deterioration in image quality. Further, since the halogen lamps 18a and 18b are also appropriately heated in the heating and pressurizing region T2, it is possible to prevent the recording medium P from taking a large amount of heat of the toner image and causing an offset phenomenon.

Further, in the image forming apparatus 1 of the present embodiment, the far infrared heater 15a is
a, 18b, the toner is heated to a temperature higher than the heating temperature of the pressure rolls 17a, 17b. Therefore, even if the pressure contact time between the intermediate transfer body 14 and the recording medium P in the heating / pressing area T2 is shortened, the toner Since the image can be sufficiently fused and fused and the image can be transferred and fixed without causing an offset phenomenon, the intermediate transfer member 14 and the recording medium P
It is also possible to prevent the occurrence of image deviation due to deviation and image disturbance due to uneven pressing force. By these operations, the image forming apparatus 1 of the present embodiment can form a high-quality image at high speed without causing image disturbance on both sides of the recording medium even in the double-sided recording mode.

In the present embodiment, as described above, the mode in which the far-infrared heater 15a heats the intermediate transfer body 14 to a temperature equal to or higher than the melting temperature of the toner is described. The temperature at which the body 14 is heated is not necessarily limited to such a temperature, and may be lower than the melting temperature of the toner. However, by heating the intermediate transfer body 14 to a temperature higher than the melting temperature of the toner, the following advantages can be obtained. Therefore, it is preferable to heat the intermediate transfer body 14 to a temperature higher than the melting temperature of the toner. Even if the intermediate transfer member 14 is heated, the toner image on the intermediate transfer member
It does not reach the same temperature as 4. In particular, in the case of a multicolor toner image composed of a plurality of layers, even if the intermediate transfer member 14 is heated to the melting temperature of the toner, the air existing between the toner particles hinders heat transfer, so that it takes a long time for the toner to melt and fuse. It takes time. Therefore, in the image forming apparatus 1 of the present embodiment,
Before the intermediate transfer member 14 is pressed against the recording medium P, the intermediate transfer member 14
Is heated to a temperature higher than the melting temperature of the toner by the far-infrared heater 15a, thereby giving a large temperature gradient between the intermediate transfer member 14 and the toner image thereon. Since the heat transfer is quickly performed and the toner image on the intermediate transfer body 14 can be reliably melted and fused before the pressure contact with the recording medium P, the transfer and fixing can be performed at high speed without causing an offset phenomenon.

In the present embodiment, as described above, the halogen lamps 18a and 18b are
In this embodiment, at least the heating temperature of the pressure roller 17b on the recording medium P side of the recording medium P is kept at a temperature lower than the melting temperature of the toner. Is not necessarily limited to such a temperature, and may be a temperature higher than the melting temperature of the toner. However, since the following advantages can be obtained by keeping at least the heating temperature of the pressure roll 17b on the recording medium P side below the melting temperature of the toner, it is preferable to keep the temperature below the melting temperature of the toner. That is, with this configuration, the toner image sandwiched between the intermediate transfer body 14 and the recording medium P is not excessively heated, and the back surface of the recording medium P is not heated to a temperature higher than the toner melting temperature. Even when image recording is performed on both sides of the recording medium P, image disturbance due to toner flow does not occur. Furthermore, by heating the toner image to an appropriate temperature equal to or lower than the melting temperature of the toner, it is possible to prevent the offset phenomenon from being caused by a large amount of heat of the toner image being taken by the recording medium P. Can be.

As a comparative example, the far infrared heater 15
a, the heating temperature of the pressure roll 17a by the halogen lamp 18a is set to 165.
When the temperature was controlled at 100 ° C. and the heating temperature of the pressure roll 17b by the halogen lamp 18b was controlled at 100 ° C., image formation was poor. Further, the temperature of the intermediate transfer body 14 by the far infrared heater 15a is set to 110 ° C.
By controlling the heating temperature of the pressure roll 17a by the halogen lamp 18a to 165 ° C. and the heating temperature of the pressure roll 17b by the halogen lamp 18b to 120 ° C., image recording was performed on both sides of the recording medium P. The image on the back side (the surface formed by forming the first image) during image recording on the surface was disturbed, and remarkable deterioration in image quality was observed.

Next, a second embodiment will be described.
FIG. 2 is a schematic configuration diagram of a second embodiment of the image forming apparatus of the present invention. The image forming apparatus 2 illustrated in FIG. 2 does not include the non-contact type far-infrared heater 15a included in the image forming apparatus 1 illustrated in FIG.
As the intermediate transfer member heating means, there is provided a contact heating member 15b for heating the intermediate transfer member 14 while contacting the back surface of the intermediate transfer member 14 opposite to the surface carrying the toner image. The components other than the intermediate transfer member heating means are the same as those of the image forming apparatus 1 shown in FIG.

Unlike the far-infrared heater 15a in the image forming apparatus 1 shown in FIG. 1, the contact-type heating member 15b comes into contact with the back surface of the intermediate transfer body 14 opposite to the surface carrying the toner image. And the intermediate transfer member 14 by heat conduction
Heat. The toner image is heated indirectly via the intermediate transfer member 14. As the contact-type heating member 15b, a member formed by attaching a silicone rubber heater to an aluminum plate curved in accordance with the shape of the movement path of the intermediate transfer body 14 is used. The surface of the contact-type heating member 15b on which the silicone rubber heater is not attached is placed on the intermediate transfer member 1.
4 so as to be in contact therewith. The contact time between the intermediate transfer member 14 and the contact-type heating member 15b can be freely set by adjusting the length of the contact-type heating member 15b in the moving direction of the intermediate transfer member 14 and the moving speed of the intermediate transfer member 14. By making the contact time sufficient, the intermediate transfer member 14
Can be transferred and fixed without defects such as image disturbance and image omission even when the image is circulated at high speed, and a high-quality image can be obtained.

The contact-type heating member 15b is not limited to the above-described one using the silicone rubber heater and the aluminum plate, but may have any configuration as long as it can uniformly heat the intermediate transfer member 14. Further, the contact-type heating member 15b may be constituted by a single member, or may be constituted by combining a plurality of members. With the image forming apparatus 2 configured as above, the toner is used at a melting temperature of 115 ° C., the moving speed of the intermediate transfer member is set to 160 mm / s, and the heating temperature of the intermediate transfer member 14 by the contact-type heating member 15b is set to approximately 165 ° C. Next, an image forming result when an image is formed on A4 size recording paper at a speed of 40 sheets per minute will be described. The heating temperature of the intermediate transfer member 14 by the contact type heating member 15b was measured on the toner image bearing surface side of the intermediate transfer member 14 closest to the pressing roll 17a of the contact type heating member 15b. The heating temperature of the pressure roll 17a by the halogen lamp 18a is controlled to 120 ° C., and the heating temperature of the pressure roll 17b by the halogen lamp 18b is 100 ° C.
C., an image was formed on the first surface of the recording medium P, and an image was also formed on the second surface of the recording medium P. The image thus obtained has high image quality without image disturbance in both the double-sided recording mode and the single-sided recording mode.

As described above, in the present embodiment, the intermediate transfer member 14 serves as an intermediate transfer member heating means while being in contact with the back surface of the intermediate transfer member 14 opposite to the surface carrying the toner image.
Is provided with the contact-type heating member 15b for heating
Since the heating time required to sufficiently raise the temperature of the intermediate transfer member 14 can be set independently of the heating in the heating and pressurizing region T2, the degree of freedom in designing the image forming apparatus increases, and the image forming apparatus It is possible to flexibly cope with miniaturization and high-speed operation. The heating time of the intermediate transfer member by the contact-type heating member 15b may be a time sufficient for the intermediate transfer member 14 to be heated to the toner melting temperature or higher. It is desirable to secure a sufficient heating time so that the temperature distribution in the thickness direction of the substrate becomes uniform. The heating time varies depending on the material of the toner, the material and thickness of the intermediate transfer body 14, and the specification of the contact heating member 15b, but it is specifically preferable that the heating time is 0.3 seconds or more.

Next, a third embodiment will be described.
FIG. 3 is a schematic configuration diagram of a third embodiment of the image forming apparatus of the present invention. The image forming apparatus 3 shown in FIG. 3 includes a heat exchanger 22 in addition to the contact-type heating member 15b as an intermediate transfer body heating unit provided in the image forming apparatus 2 shown in FIG. . The heat exchanger 22 contacts the back surface of the intermediate transfer member 14 and absorbs heat from the intermediate transfer member 14 on the downstream side in the moving direction of the intermediate transfer member 14 with respect to the pressure rolls 17a and 17b. Pressure roll 17
A heat radiating portion 24 that contacts the back surface of the intermediate transfer member 14 and supplies heat to the intermediate transfer member 14, and a portion between the heat absorbing portion 23 and the heat radiating portion 24 upstream of the intermediate transfer member 14 in the moving direction of the intermediate transfer member 14 a and 17 b And a heat transfer section 25 for transferring heat. In the present embodiment, a heat pipe is used as the heat transfer unit 25. This image forming apparatus 3 is configured similarly to the image forming apparatus 2 shown in FIG. 2 except that the heat exchanger 22 is provided.

By providing the heat exchanger 22, in the present embodiment, the high-temperature heat-absorbing section 23 and the low-temperature radiating section 24
The intermediate transfer member 14 can be heated at the heat radiating portion 24 without providing a heat source. For the heat absorbing portion 23 and the heat radiating portion 24, a member having good heat conductivity, for example, an aluminum block is used. As the heat transfer unit 25, a heat pipe is used in the present embodiment. However, the heat transfer unit 25 is not limited to the heat pipe, and may use a metal body having good heat conductivity, a contacting or rotating metal belt, or the like. You may. However, using a heat pipe has the advantage that the heat transfer speed inside the heat pipe is as high as the speed of sound, and the heat transfer section can be made compact. It is possible to obtain a simple image forming apparatus. In the present embodiment, in order to further improve the heat transfer efficiency of the heat pipe, the heat pipe is covered with a heat insulating material for heat insulation.

The image forming apparatus 3 having the above-mentioned structure uses a toner having a melting temperature of 115 ° C. and a glass transition temperature of 60 ° C., the moving speed of the intermediate transfer member is set to 160 mm / s, and the intermediate transfer member 14 by the contact heating member 15b is used. The image forming result in the case where an image is formed at a speed of 40 sheets per minute on A4 size recording paper at a heating temperature of about 165 ° C. will be described below. The heating temperature of the intermediate transfer member 14 by the contact type heating member 15b was measured on the toner image bearing surface side of the intermediate transfer member 14 closest to the pressing roll 17a of the contact type heating member 15b. The heating temperature of the pressure roll 17a by the halogen lamp 18a is controlled to 120 ° C., and the heating temperature of the pressure roll 17b by the halogen lamp 18b is 100 ° C.
C., an image was formed on the first surface of the recording medium P, and an image was also formed on the second surface of the recording medium P. The image thus obtained has high image quality without image disturbance in both the double-sided recording mode and the single-sided recording mode.

In the image forming process of this embodiment, the temperature of the intermediate transfer body 14 immediately after passing through the heat absorbing section 23 of the heat exchanger 22 is about 80 ° C. As a comparative example, heat exchanger 2
When the temperature of the intermediate transfer member 14 at the same portion without 2 was measured, it was about 110 ° C. Intermediate transfer member 1
If the temperature of the image transfer member 4 is too high, the image carrier may be thermally degraded, or the high heat of the intermediate transfer member 14 may cause the image carrier 10a, 10a.
0b, 10c, 10d, the developing units 11a, 11b,
The temperature of the intermediate transfer body 14 needs to be lower than the glass transition temperature of the toner, because the temperature may be transmitted to the toner 11c and 11d and cause the toner to cause blocking. Therefore, in the present embodiment, the cooling device 20 and the support rolls 19c, 19c
The intermediate transfer member 14 is cooled to about 50 ° C. by d.

In the present embodiment, the temperature immediately after the intermediate transfer body 14 cooled to about 50 ° C. has passed through the heat radiating section 24 of the heat exchanger 22 is about 75 ° C. At this time, the power consumption required for transferring and fixing the toner image onto the recording medium P in image formation, that is, the power supplied to the contact heating member 15b and the halogen lamps 18a and 18b was measured. Power consumption is about 13
In contrast to 00W, the power consumption when the heat exchanger 22 is provided is about 1050W, and the power consumption is reduced by about 250W. Thus, by providing the heat exchanger 22, the residual heat is recovered and reused, and the image formation can be performed with low power consumption.

Next, a fourth embodiment will be described.
FIG. 4 is a schematic configuration diagram of a fourth embodiment of the image forming apparatus of the present invention. The image forming apparatus 4 shown in FIG. 4 includes heat absorbing sections 23a, 23b, 23c,..., And heat radiating sections 24a, 24b, similarly to the heat exchanger 22 provided in the image forming apparatus 3 shown in FIG. , 24c,... And heat transfer section 2
, A plurality of sets of heat exchangers 22a, 22b, 22c,... Comprising 5a, 25b, 25c,.
This image forming apparatus 4 has the same configuration as the image forming apparatus 3 shown in FIG. 3 except that a plurality of sets of heat exchangers 22a, 22b, 22c,.

The plural sets of heat exchangers 22a, 22b, 2
In this embodiment, the temperature of the heat radiating portion 24a on the most upstream side in the moving direction of the intermediate transfer member 14 is lowest in the plurality of heat radiating portions, and the temperature sequentially increases toward the downstream side. ing. On the other hand, among the plurality of heat absorbing portions, the heat absorbing portion on the most upstream side in the moving direction of the intermediate transfer member 14 has the highest temperature, and the temperature sequentially decreases toward the downstream side, and the heat absorbing portion 23a on the most downstream side has the lowest temperature. Therefore, each of the heat exchangers 22a, 22b, 22c,... Can efficiently exchange heat.

Using the toner having a melting temperature of 115 ° C. and a glass transition temperature of 60 ° C., the moving speed of the intermediate transfer member is set to 160 mm / s, and the intermediate transfer member 14 is driven by the contact heating member 15b. The image forming result in the case where an image is formed at a speed of 40 sheets per minute on A4 size recording paper at a heating temperature of about 165 ° C. will be described below. The heating temperature of the intermediate transfer member 14 by the contact type heating member 15b was measured on the toner image bearing surface side of the intermediate transfer member 14 closest to the pressing roll 17a of the contact type heating member 15b. The heating temperature of the pressure roll 17a by the halogen lamp 18a is controlled to 120 ° C., and the heating temperature of the pressure roll 17b by the halogen lamp 18b is 100 ° C.
C., an image was formed on the first surface of the recording medium P, and an image was also formed on the second surface of the recording medium P. The image thus obtained has high image quality without image disturbance in both the double-sided recording mode and the single-sided recording mode.

In the image forming process of this embodiment, the temperature of the intermediate transfer body 14 immediately after passing through the heat absorption section 23a on the most downstream side in the moving direction of the intermediate transfer body 14 among the plurality of heat absorption sections is about 70 ° C. As a comparative example, the heat exchangers 22a, 22
When the temperature of the intermediate transfer member 14 at the same site without 2b, 22c,... Was measured, it was about 110 ° C. If the temperature of the intermediate transfer member 14 becomes too high, the high heat of the intermediate transfer member 14 causes the image carriers 10a, 10b, 10c, 1
The temperature of the intermediate transfer body 14 needs to be lower than the glass transition temperature of the toner because the toner may be transmitted to the developing devices 11a, 11b, 11c, and 11d via 0d and blocking may occur. Therefore, in the present embodiment, the intermediate transfer body 14 is cooled to approximately 50 ° C. by the cooling device 20 and the support rolls 19c and 19d.

In the present embodiment, the temperature immediately after the intermediate transfer member 14 cooled to approximately 50 ° C. has passed through the heat radiation portion on the downstream side in the moving direction of the intermediate transfer member 14 among the plurality of heat radiation portions is approximately 85 ° C. It is. At this time, power consumption required for transferring and fixing the toner image onto the recording medium P in the image formation, that is, the contact heating member 15b and the halogen lamp 18
As a result of measuring the power supplied to the heat exchangers 22a, 22b, 22c,..., the power consumption without the heat exchangers 22a, 22b, 22c,.
Power consumption in the presence of 22b, 22c,... Is about 950 W, and power consumption is reduced by about 350 W.

As described above, the plurality of heat exchangers 22a, 22
, 22c,...
4 is gradually heated by a plurality of heat radiating portions and gradually cooled by a plurality of heat absorbing portions, so that the heating and cooling of the intermediate transfer member are efficiently performed, and therefore, the residual heat is sufficiently recovered and reused. High-speed image formation can be performed with power consumption.

Next, a fifth embodiment will be described.
FIG. 5 is a schematic configuration diagram of a fifth embodiment of the image forming apparatus of the present invention. In the image forming apparatus 5 shown in FIG. 5, the intermediate transfer body heater 15b is located on the downstream side in the moving direction of the intermediate transfer body 14 from the position where the heat radiators 24a, 24b, 24c,. Transfer member 1 than the installation position of
4, supports the intermediate transfer member 14 by rotating while being in contact with the back surface of the intermediate transfer member 14,
A support roll 26 having a halogen lamp 27 therein is provided. This image forming apparatus 5 except that a support roll 26 having a halogen lamp 27 therein is provided.
Has the same configuration as the image forming apparatus 4 shown in FIG.

Since the support roll 26 having the halogen lamp 27 is provided, the support roll 26 can be appropriately heated from the inside, so that high-speed and reliable transfer and fixing can be performed. The intermediate transfer member 14 includes a contact-type heating member 15b and a plurality of heat exchangers 22a and 22a that are in contact with the surface of the intermediate transfer member 14 opposite to the toner image bearing surface.
.. circulate while sliding on the heat radiating portions and the heat absorbing portions b, 22c,..., and receive strong frictional resistance due to the sliding. In particular, where the curvature of the intermediate transfer member 14 is large,
The normal reaction of the belt tension to the sliding surface increases, and the frictional force increases, so that a large load is applied to the driving of the intermediate transfer member 14. Thus, by supporting a portion of the intermediate transfer member 14 having a large curvature by rolling friction, the driving load of the intermediate transfer member 14 can be greatly reduced, and as a result, the belt can be driven with high accuracy.

Note that other heating means other than the halogen lamp may be used as the heat source inside the support roll 26. With the image forming apparatus 5 configured as described above, the melting temperature 115
Using a toner having a glass transition temperature of 60 ° C. and a moving speed of the intermediate transfer member of 160 mm / s.
The image forming result when the image forming is performed at a speed of 40 sheets per minute on A4 size recording paper at a heating temperature of the intermediate transfer body 14 of about 165 ° C. by b will be described below. The heating temperature of the intermediate transfer member 14 by the contact type heating member 15b was measured on the toner image bearing surface side of the intermediate transfer member 14 closest to the pressing roll 17a of the contact type heating member 15b. The heating temperature of the pressure roll 17a by the halogen lamp 18a is controlled to 120 ° C., and the heating temperature of the pressure roll 17b by the halogen lamp 18b is controlled to 100 ° C. to form an image on the first surface of the recording medium P. An image was also formed on the second surface of the recording medium P. The image thus obtained has high image quality without image disturbance in both the double-sided recording mode and the single-sided recording mode.

In the image forming process of this embodiment, the temperature of the intermediate transfer body 14 immediately after passing through the heat absorption section 23a on the most downstream side in the moving direction of the intermediate transfer body 14 among the plurality of heat absorption sections is about 70 ° C. As a comparative example, the heat exchangers 22a, 22
When the temperature of the intermediate transfer member 14 at the same site without 2b, 22c,... Was measured, it was about 110 ° C. If the temperature of the intermediate transfer member 14 becomes too high, the high heat of the intermediate transfer member 14 causes the image carriers 10a, 10b, 10c, 1
The temperature of the intermediate transfer body 14 needs to be lower than the glass transition temperature of the toner because the toner may be transmitted to the developing devices 11a, 11b, 11c, and 11d via 0d and blocking may occur. Therefore, in the present embodiment, the intermediate transfer body 14 is cooled to approximately 50 ° C. by the cooling device 20 and the support rolls 19c and 19d.

In the present embodiment, the temperature immediately after the intermediate transfer member 14 cooled to approximately 50 ° C. has passed through the heat radiation portion on the most downstream side in the moving direction of the intermediate transfer member 14 among the plurality of heat radiation portions is approximately 85 ° C. It is. Here, the halogen lamp 27
When the support roll 26 is heated to 85 ° C. and the case where the heating by the halogen lamp 27 is not performed is compared, the temperature of the intermediate transfer body 14 after passing through the support roll 27 when the support roll 26 is not heated by the internal heat source is compared. Is a few degrees lower than when heated with a halogen lamp 27,
Become strong.

Heat radiators 24a, 24b, 24 of the heat exchanger
When the intermediate transfer member 14 heated by the contact-type heating member 15b is in contact with a member having a temperature lower than the temperature of the intermediate transfer member 14, heat is taken away and energy is lost. Therefore, the heat radiating portions 24a, 24
, 24c,... to the pressure rolls 17a, 17b,
6 is heated to a temperature close to the temperature of the heat radiating portion of the heat exchanger disposed on the upstream side, thereby avoiding the occurrence of heat energy loss. The support roll 26
Is heated to a temperature close to the temperature of the heat radiating portion of the heat exchanger, almost no heat exchange occurs between the support roll 26 and the intermediate transfer body 14, so that the support roll 2
The loss of energy for heating 6 is almost negligible.

As a result of measuring the power consumption required for transferring and fixing the toner image to the recording medium P in this embodiment, that is, the power supplied to the contact heating member 15b, the halogen lamps 18a and 18b, and the halogen lamp 27, The power is about 950 W, and the same result as in the fourth embodiment can be obtained. Thus, the halogen lamp 27
, The intermediate transfer member 14 can be driven accurately with almost the same power consumption, and high-speed, high-quality image formation can be performed.

Next, a sixth embodiment will be described.
FIG. 6 is a schematic configuration diagram of a sixth embodiment of the image forming apparatus of the present invention. The image forming apparatus 6 shown in FIG. 6 is different from the image forming apparatus 5 shown in FIG. 5 in that the positions of the heat radiating portions 24a, 24b, 24c,. Heat insulating members 28a and 28b that cover the intermediate transfer body 14 that blocks heat radiation from the surface of the intermediate transfer body 14 are added to the regions up to the installation positions of 23b, 23c,. In the present embodiment, the heat insulating members 28a, 28b are divided into two parts, and the heat radiating parts 24a, 24b, 24
The heat absorbing portions 23a, 23b, 23
are provided over the entire area up to the installation position of c,..., but may be provided only in a partial area instead of the entire area. This image forming apparatus 6 is the same as the image forming apparatus 5 shown in FIG. 5 except that the heat insulating members 28a and 28b are provided.
It has the same configuration as

By providing the heat insulating members 28a and 28b, loss of heat energy due to heat radiation from the high-temperature intermediate transfer body 1 can be reduced. Heat insulating members 28a,
Glass wool having heat resistance can be used as 28b. Further, the heat insulating members 28a and 28b
Since a high effect can be obtained by arranging the intermediate transfer member 14 close to the intermediate transfer member 14, the distance between the heat insulating members 28a and 28b and the intermediate transfer member 14 is desirably several mm or less. In the present embodiment, 2 m from the surface of the intermediate transfer body 14
Insulation members 28a, 28 using glass wool at the position of m
b is arranged. The halogen lamps 18a, 18
It is preferable to arrange a heat insulating member also around the pressure rolls 17a and 17b heated by b.

Using the toner having a melting temperature of 115.degree. C. and a glass transition temperature of 60.degree. C., the moving speed of the intermediate transfer member is set to 160 mm / s, and the intermediate transfer member 14 is driven by the contact heating member 15b. The image forming result in the case where an image is formed at a speed of 40 sheets per minute on A4 size recording paper at a heating temperature of about 165 ° C. will be described below. The heating temperature of the intermediate transfer member 14 by the contact type heating member 15b was measured on the toner image bearing surface side of the intermediate transfer member 14 closest to the pressing roll 17a of the contact type heating member 15b. The heating temperature of the pressure roll 17a by the halogen lamp 18a is controlled to 120 ° C., and the heating temperature of the pressure roll 17b by the halogen lamp 18b is 100 ° C.
C., an image was formed on the first surface of the recording medium P, and an image was also formed on the second surface of the recording medium P. The image thus obtained has high image quality without image disturbance in both the double-sided recording mode and the single-sided recording mode.

In the image forming process of this embodiment, the temperature of the intermediate transfer body 14 immediately after passing through the heat absorption section 23a on the most downstream side in the moving direction of the intermediate transfer body 14 among the plurality of heat absorption sections is about 70 ° C. As a comparative example, the heat exchangers 22a, 22
When the temperature of the intermediate transfer member 14 at the same site without 2b, 22c,... Was measured, it was about 110 ° C. If the temperature of the intermediate transfer member 14 becomes too high, the high heat of the intermediate transfer member 14 causes the image carriers 10a, 10b, 10c, 1
The temperature of the intermediate transfer body 14 needs to be lower than the glass transition temperature of the toner because the toner may be transmitted to the developing devices 11a, 11b, 11c, and 11d via 0d and blocking may occur. Therefore, in the present embodiment, the intermediate transfer body 14 is cooled to approximately 50 ° C. by the cooling device 20 and the support rolls 19c and 19d.

In this embodiment, the temperature immediately after the intermediate transfer member 14 cooled to approximately 50 ° C. has passed through the heat radiation portion on the most downstream side in the moving direction of the intermediate transfer member 14 among the plurality of heat radiation portions is approximately 90 ° C. It is. Thereafter, the support roll 26 is heated to 90 ° C. by the halogen lamp 27. At this time, power consumption required for transferring and fixing the toner image onto the recording medium P in image formation, that is, the contact-type heating member 15b,
As a result of measuring the power supplied to the halogen lamps 18a, 18b and the halogen lamp 27, the heat exchanger 22
a, 22b, 22c,... and heat insulating members 28a, 2
The power consumption without 8b is about 1300 W, while the power consumption with heat exchangers 22a, 22b, 22c,... And heat insulating members 28a and 28b is about 900W, and the power consumption is reduced by about 400W. Is done.

As described above, since the heat insulating members 28a and 28b are provided, heat radiation from the surface of the intermediate transfer member 14 in a high temperature state is prevented, so that loss of heat energy can be suppressed, and the heat insulating members 28a and 28b can be suppressed. Since the reflected radiant heat from 28b can be reused for heating the toner, high-speed transfer fixing with low energy consumption becomes possible. Note that the heat insulating members 28a and 28b block heat radiation from the surface of the intermediate transfer member 14 and that the heat exchanger 22 contacts the surface of the intermediate transfer member 14 opposite to the toner image bearing surface.
Radiator 24, contact-type heating member 15b, pressure roll 17
The effect can be further enhanced by covering the periphery of a, 17b, and the like with a heat insulating material and blocking heat radiation from the back surface of the intermediate transfer body.

[0068]

As described above, according to the image forming apparatus of the present invention, the image forming apparatus of the simultaneous transfer and fixing type using the intermediate transfer member is provided with the intermediate transfer member rather than the pressing member of the intermediate transfer member. The intermediate transfer body heating means for heating the portion on the upstream side in the moving direction of the pressing member to a temperature higher than the heating temperature of the pressing member by the pressing member heating means enables high quality images to be recorded on both sides. It is possible to easily realize a high-speed and low-energy consumption image forming apparatus.

[Brief description of the drawings]

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

FIG. 2 is a schematic configuration diagram of a second embodiment of the image forming apparatus of the present invention.

FIG. 3 is a schematic configuration diagram of a third embodiment of the image forming apparatus of the present invention.

FIG. 4 is a schematic configuration diagram of a fourth embodiment of the image forming apparatus of the present invention.

FIG. 5 is a schematic configuration diagram of a fifth embodiment of the image forming apparatus of the present invention.

FIG. 6 is a schematic configuration diagram of a sixth embodiment of the image forming apparatus of the present invention.

[Explanation of symbols]

1, 2, 3, 4, 5, 6 Image Forming Apparatus 10a, 10b, 10c, 10d Image Carrier 11a, 11b, 11c, 11d Developing Unit 12a, 12b, 12c, 12d Primary Charger 13 Optical Scanning Device 14 Intermediate Transfer Body 15a Far-infrared heater 15b Contact-type heating member 16a, 16b, 16c, 16d Corotron transfer unit 17a, 17b Pressure roll 18a, 18b Halogen lamp 19a, 19b, 19c, 19d Support roll 20 Cooling device 21 Tray 22, 22a, 22b, 22c,... Heat exchangers 23, 23a, 23b, 23c,... Heat absorbing portions 24, 24a, 24b, 24c,... Heat dissipating portions 25, 25a, 25b, 25c,. Reference Signs 26 Support roll 27 Halogen lamp 28a, 28b Heat insulating member 30 Recording medium reversing device 31, 32 Transport Direction switching device 33 recording medium reversing section 34,35a, 35b, 35c, 35d, 35e recording medium transport roll 36 recording medium outlet

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takayuki Yamashita 430 Border, Nakaicho, Ashigarakami-gun, Kanagawa Green Tech Nakai Inside Fuji Xerox Co., Ltd.

Claims (11)

[Claims] An image transfer member on which a toner image is formed; an intermediate transfer member which moves while approaching or in contact with the image carrier to transfer a toner image formed on the image carrier; Transfer means for transferring the toner image formed on the image carrier onto the intermediate transfer member; and interposing the toner image on the intermediate transfer member between the transfer member and the intermediate transfer member on which the toner image has been transferred. A pair of pressure members for pressing a predetermined recording medium on top of each other so as to sandwich the intermediate transfer member, the toner image, and the recording medium, and a heating member for heating the pressure member Means, wherein a portion of the intermediate transfer body on the upstream side in the moving direction of the intermediate transfer member with respect to the pressing member is controlled by a heating temperature of the pressing member by the pressing member heating unit. The intermediate transfer body heating means Image forming apparatus, characterized in that the. 2. An image forming apparatus according to claim 1, wherein said intermediate transfer body heating means heats said intermediate transfer body to a temperature higher than a melting temperature of toner. 3. The pressure member heating means for keeping a heating temperature of at least a pressure member on the recording medium side of the pair of pressure members at a temperature lower than a melting temperature of toner. The image forming apparatus according to claim 1. 4. The image forming apparatus according to claim 1, wherein said intermediate transfer body heating means heats said intermediate transfer body from a position distant from said intermediate transfer body. 5. The intermediate transfer body is formed in an endless belt shape, and the intermediate transfer body heating means carries a toner image of the intermediate transfer body transferred from the image carrier. 2. The image forming apparatus according to claim 1, further comprising a heating member for heating the intermediate transfer body while being in contact with a back surface opposite to the front surface. 6. A heat absorbing portion that contacts a back surface of the intermediate transfer member and absorbs heat from the intermediate transfer member at a position downstream of the pressure member in the moving direction of the intermediate transfer member; A heat dissipating portion that contacts the back surface of the intermediate transfer member and supplies heat to the intermediate transfer member on the upstream side in the moving direction of the intermediate transfer member, and a heat transfer portion that performs heat transfer between the heat absorbing portion and the heat dissipating portion. The image forming apparatus according to claim 5, further comprising a heat exchanger comprising: 7. The image forming apparatus according to claim 6, wherein the heat exchanger includes a plurality of sets of the heat absorbing section, the heat radiating section, and the heat transfer section. 8. The image forming apparatus according to claim 6, wherein the heat transfer section is a heat pipe. 9. An intermediate transfer body moving direction downstream of an installation position of the heat radiating unit and a heating member constituting the intermediate transfer body heating unit at an upstream side of a movement direction of the intermediate transfer body. 7. The image forming apparatus according to claim 6, further comprising a support roll that supports the intermediate transfer member by rotating while contacting the back surface of the intermediate transfer member. 10. The support roll according to claim 9, wherein a heat source is provided inside the support roll.
The image forming apparatus as described in the above. 11. A heat radiation from a surface of the intermediate transfer body is blocked in an entire area or a partial area from an installation position of the heat radiation section to an installation position of the heat absorption section along a movement path of the intermediate transfer body. 7. An image forming apparatus according to claim 6, further comprising a heat insulating member for covering said intermediate transfer member.