JP2000275974A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the image forming device of a resin intermediate transfer belt system by which excellent image quality is obtained and whose life is prolonged and whose maintainability is improved by setting a belt-like intermediate transfer body as a seamless belt. SOLUTION: An electrostatic latent image on a latent image carrier is developed as a visible image, and after it is transferred to an intermediate transfer body, it is transferred to a transfer material again in this image forming device. In this case, a device possesses an intermediate transfer unit provided with a mechanism to always lay the belt-like intermediate transfer body of thin film between plural axes by the tension of 100 kg/cm2-1000 g/cm2 and to apply an electric field while directly coming into contact with the intermediate transfer body, and also the belt-like intermediate transfer body is set to be the seamless belt continuously molded with thermoplastic resin whose stress is 2 kgf/mm2-8 kgf/mm2 when it is elongated by 2% and whose thickness is 30 μm-300 μm.

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 using an electrophotographic system, and more particularly, to a method of transferring a toner image formed on a first image carrier once to an intermediate transfer belt and then to an intermediate transfer belt. The present invention relates to an electrophotographic image forming apparatus that obtains an image-formed product by performing an image forming process.

[0002]

2. Description of the Related Art An image forming apparatus using an intermediate transfer belt sequentially transfers a plurality of component color images of color image information and multicolor image information in a layered manner to form an image formed product in which a color image or a multicolor image is synthesized and reproduced. The present invention is effective as a color image forming apparatus or a multicolor image forming apparatus for outputting, or an image forming apparatus having a color image forming function or a multicolor image forming function.

FIG. 1 is a schematic diagram showing an example of an image forming apparatus using an intermediate transfer belt.

FIG. 1 shows a color image forming apparatus (copier or laser beam printer) using an electrophotographic process.

Reference numeral 1 denotes a drum-shaped electrophotographic photosensitive member (hereinafter, referred to as a photosensitive drum) as a first image carrier, which is rotated at a predetermined peripheral speed (process speed) in the direction of an arrow.

[0006] The photosensitive drum 1 rotates in the primary charging device 2 during the rotation process.
, And is uniformly charged to a predetermined polarity and potential, and then subjected to exposure 3 by image exposure means 3 (not shown). In this way, an electrostatic latent image corresponding to the first color component image (for example, a yellow color component image) of the target color image is formed.

Next, the electrostatic latent image is developed into a first color yellow component image by a first developing device (yellow color developing device 41). At this time, the second to fourth developing units, namely, the magenta developing unit 42, the cyan developing unit 43, and the black developing unit 44 are not operating and do not act on the photosensitive drum 1, so that The one-color yellow component image is not affected by the second to fourth developing units.

The intermediate transfer belt 20 is driven to rotate at the same peripheral speed as the photosensitive drum 1 in the direction of the arrow.

The first color yellow component image formed on the photosensitive drum 1 is transferred to the photosensitive drum 1 and the intermediate transfer belt 20.
In the process of passing through the nip portion, the toner image is sequentially transferred to the outer peripheral surface of the intermediate transfer belt 20 by an electric field formed by a bias applied to the intermediate transfer belt 20 from the bias power supply 29 via the roller 62. This step is called primary transfer, the roller 62 is called a primary transfer roller, and the applied bias is called a primary transfer bias.

The surface of the photosensitive drum 1 on which the transfer of the first color yellow toner image corresponding to the intermediate transfer belt 20 has been completed is cleaned by the cleaning device 13.

[0011] Similarly, a magenta toner image of the second color, a cyan toner image of the third color, and a black toner image of the fourth color are successively superimposed on the intermediate transfer belt 20 and transferred to correspond to the target color image. Thus, a combined color toner image is formed.

Next, the composite color toner image is transferred to a transfer material. This step is called secondary transfer. Numeral 63 denotes a secondary transfer roller, which is supported in parallel with the secondary transfer opposing roller 64 and is disposed on the lower surface of the intermediate transfer belt 20 so as to be separated therefrom.

A primary transfer bias for transferring a toner image from the photosensitive drum 1 to the intermediate transfer belt 20 is applied from a bias power supply 29 with a polarity opposite to that of the toner. The applied voltage is in a range of, for example, +100 V to +2 kV.

In the primary transfer process of the first to third color toner images from the photosensitive drum 1 to the intermediate transfer belt 20,
The next transfer roller 63 can be separated from the intermediate transfer belt 20.

The full-color image transferred onto the intermediate transfer belt 20 is
The transfer material P is fed at a predetermined timing from the paper feed roller 11 to a contact portion between the intermediate transfer belt 20 and the secondary transfer roller 63, and the secondary transfer bias is applied from the bias power supply 28 to the secondary transfer. By being applied to the roller 63, secondary transfer is performed on the transfer material P. The transfer material P to which the toner image has been transferred is introduced into the fixing device 15 and is fixed by heating.

After the transfer of the image to the transfer material P is completed, the toner (transfer residual toner) remaining on the intermediate transfer belt is scraped off by the cleaning blade 50 and is carried to a waste toner box.

FIG. 2 is a view showing another cleaning method. After the image transfer to the transfer material P is completed, the intermediate transfer belt 2
The transfer residual toner charging member 52, which is freely separated from and attached to the photosensitive drum 1, is brought into contact with the transfer residual toner, and a bias having a polarity opposite to that of the photosensitive drum 1 is applied to the transfer residual toner. You.

The intermediate transfer belt 20 is cleaned by being electrostatically transferred onto the photosensitive drum 1 in the vicinity of the transfer residual toner and the photosensitive drum 1 and in the vicinity thereof. Finally, it is collected by the photosensitive drum cleaning device 13. At this time, by performing the primary transfer step and collecting the transfer residual toner on the photosensitive drum at the same time, the intermediate transfer belt can be cleaned without lowering the throughput. The bias applied to the transfer residual toner charging member 52 is preferably obtained by superimposing an AC component on a DC component because the cleaning performance is higher.

A color electrophotographic apparatus having an image forming apparatus using such an intermediate transfer belt is pasted or adsorbed on a transfer drum, which is a conventional technique, and an image is transferred therefrom onto a first image carrier. Color electrophotographic apparatus having an image forming apparatus, for example, JP-A-63-3019
Compared with the transfer device described in Japanese Patent Application Publication No. 60-160, there is no need for any processing and control (for example, gripping by a gripper, adsorbing, giving a curvature, etc.) to the transfer material as the second image carrier. Since the image can be transferred from the intermediate transfer belt to an envelope, postcard, label paper, etc.
From 0 g / m ² approximately thin paper up to 200 g / m ² approximately thick paper has the advantage of wide or narrow or wide, can be transferred irrespective of the length of length.

Further, as for the intermediate transfer member, the resin intermediate transfer belt having a small thickness is increasing due to the miniaturization of the apparatus and the easiness of layout, and the secondary transfer system uses a copier or a printer as described above. In consideration of the environment, a transfer roller system which generates less ozone is mainly used.

[0021]

The image forming apparatus using the resin intermediate transfer belt system has many advantages.

However, the resin intermediate transfer belt tends to have a large color shift when an image is superimposed on a rigid intermediate transfer drum, and this tends to cause a problem in image quality. Further, a plurality of shafts for stretching the belt are required, which complicates the structure and causes an increase in cost. In order to reduce the load on the resin intermediate transfer belt, a mechanism for releasing the tension applied to the intermediate transfer belt other than during image formation can be provided, but the cost problem becomes more remarkable. The most preferable in terms of cost is a configuration in which each shaft is fixed without a tension mechanism such as a spring. The resin intermediate transfer belt main body is also susceptible to discharge damage due to bending fatigue and application of various electric fields to the surface, and is deteriorated by repeated use, and is damaged or deteriorates transfer performance. Therefore, there is still room for improvement in the image forming apparatus using the resin intermediate transfer belt in terms of image quality, body cost, and maintenance.

[0023]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a high-quality, low-cost, long-life resin having a small number of replacements of the intermediate transfer unit or an improved unnecessary maintenance. An image forming apparatus of an intermediate transfer belt type is obtained, and is achieved by the following configuration.

In an image forming apparatus, an electrostatic latent image drawn on a latent image carrier is visualized with a developer, and the obtained visible image is once transferred onto an intermediate transfer member and then transferred to a transfer material. The intermediate transfer unit constantly transfers a belt-shaped intermediate transfer body of a thin film film between a plurality of axes at 100 g / cm to 1000 g / cm
stretched at a tension of cm, has a mechanism for applying an electric field in direct contact with the intermediate transfer member, the belt-shaped intermediate transfer body is stress at 2% elongation thickness in 2kgf / mm ² ~8kgf / mm ² An image forming apparatus, which is a seamless belt continuously formed of a thermoplastic resin having a thickness of 30 μm to 300 μm.

In order to achieve the object of the present invention, it is preferable that the shafts around which the intermediate transfer belt is stretched be fixed so as to reduce costs due to simplification of the structure and to reduce movable parts which cause color shift. . Further, in order to reduce the color shift, it is necessary to apply a tension of 100 g / cm or more to the intermediate transfer belt to stabilize the running of the intermediate transfer belt. Preferably at least 200 g / cm, more preferably 300 g / cm
g / cm or more. However, this tension is 1000 g /
cm, the fatigue of the intermediate transfer belt due to the stress becomes severe, and the durability is reduced. Preferably 800 g /
cm or less.

The intermediate transfer belt used by being stretched over the intermediate transfer unit as described above is required to have a high tensile strength and a high durability since the state where the stress is always applied is maintained. For this purpose, the stress when the intermediate transfer belt is stretched by 2% is 2 kgf.
/ Mm ² or more, preferably 3 kgf / mm ² or more, and a thickness of 50 μm or more, sufficient durability can be obtained even when stretched over the above mechanism. This value is 2 kgf / mm ² and 5
If the thickness is less than 0 μm, relaxation of the belt due to tension, bending fatigue due to repeated use, and deterioration due to electric discharge cause slippage of the drive shaft, deterioration of color shift, and further damage to the intermediate transfer belt, resulting in insufficient durability. The stress at the time of 2% extension of the intermediate transfer belt is 10 kgf / mm ² , and the thickness is 300 mm.
If it exceeds μ, flexibility is insufficient, and problems such as an increase in driving torque and an increase in manufacturing cost occur.

If a high tensile strength is required for the intermediate transfer member, a molding method such as centrifugal molding or dipping is adopted using a thermosetting resin. However, these methods require time for molding, and it is difficult to reduce the manufacturing cost. Before molding, it is necessary to dissolve the resin or the precursor of the resin in an organic solvent or an acid. At this time, if an insoluble filler is added, it leads to poor dispersion such as settling or aggregation,
The intermediate transfer member lacks uniformity, and tends to cause a partial decrease in strength and a variation in resistance.

As a method for obtaining an intermediate transfer member which is low in cost and excellent in dispersion of the filler, continuous molding of a seamless belt with a thermoplastic resin is preferred. The manufacturing method is extrusion or inflation molding, continuously forming a mixture obtained by melting and kneading the necessary materials into a tube, and appropriately,
The intermediate transfer member is manufactured by cutting to a required length. According to this method, it is possible to reduce the cost of the intermediate transfer member because it is formed continuously, and it is also possible to uniformly disperse a filler having a large specific gravity and a large particle diameter.

As a material used for the intermediate transfer belt, thermoplastic polyimide, polyetherimide, polyetheretherketone, polyethersulfone, polysulfone, and polyarylate are preferable.

These materials can be melt-molded while having higher mechanical properties than general-purpose resins, and are suitably used for high durability and low cost, which are the objects of the present invention.

Further, the primary transfer simultaneous intermediate transfer body cleaning mechanism shown in FIG. 2 does not require a waste toner box for the intermediate transfer body, and is very effective in reducing the size of the apparatus, reducing costs, and improving maintainability. The intermediate transfer member of the present invention is also suitable for this system. This is because, since the intermediate transfer belt has excellent mechanical properties, sufficient durability can be maintained even when an AC electric field is applied from the residual toner charging member and the belt is repeatedly damaged by discharge.

As described above, according to the present invention, without providing a mechanism for releasing the tension applied to the intermediate transfer member, the tension is reduced due to relaxation even when the intermediate transfer member is always stretched between the fixed shafts. It is possible to obtain an intermediate transfer member which is hard to be broken and does not break even when used repeatedly for a long period of time, and it is possible to reduce the color shift, reduce the cost of the entire unit, and improve the maintainability. Further, it is possible to cope with the primary transfer simultaneous cleaning method.

Further, as described above, the intermediate transfer belt of the present invention can be mixed with various additives as needed, as long as the performance of the present invention is not impaired. For example, conductive materials such as carbon black, graphite, carbon fiber, metal powder, conductive metal oxides, organic metal oxides, organic metal salts, and conductive polymers for adjusting the resistance. Further, a resin powder or an inorganic powder may be mixed to prevent the toner from adhering. Further, multilayering may be performed by coating with various materials. In particular, a fluorine-based or silicone-based material is often used for the surface layer depending on the purpose, but this is not necessarily the case.

The intermediate transfer belt has been described above.
The belt of the present invention can provide good results when used for a transfer / conveying belt or a base layer of a photosensitive belt.

Next, the physical property measuring method of the present invention will be described.

The tension of the intermediate transfer belt is measured by a load cell incorporated in one of the intermediate transfer belt tension shafts of the image forming apparatus for performing a print test. A partial schematic is shown in FIG.
A load cell 8 reads the stress in the direction of the arrow 10 minutes after the intermediate transfer belt is laid over the apparatus, and divides the stress by the width of the intermediate transfer belt to calculate the tension per 1 cm width of the intermediate transfer belt.

The thickness of the intermediate transfer belt is an average value of 10 points measured with a micrometer at 10 arbitrary points.

For the measurement of stress at 2% elongation, three rectangular test pieces having a width of 20 mm and a length of 100 mm are cut out from the intermediate transfer belt. At this time, the longitudinal direction of the test piece is set to be the circumferential direction of the intermediate transfer belt. Next, the film thickness near the center of each test piece is measured at five points with a micrometer, and the average of the three points excluding the maximum and minimum is defined as the film thickness of the sample. The cross-sectional area is calculated by multiplying the film thickness by 20 mm in width of the test piece.

As a stress measuring device, a tensile tester, Tensilon RTC-1250A manufactured by Orientec Co., Ltd. was used. The test length was 20 mm, the test speed was 2 mm / min, and the continuous measurement was performed from 0 to 5% elongation. Record the stress. This operation is performed for three test pieces, and the value at the time of 2% extension is averaged. The value obtained by dividing the measured value by the above-mentioned test piece cross-sectional area is the stress at the time of 2% elongation, and the unit is kgf / mm ² .

[0040]

The present invention will be described below in detail with reference to examples.

Example 1 Preparation of Intermediate Transfer Belt The following materials were melt-kneaded with a twin-screw extruder to prepare material pellets.

Polysulfone 100 parts by weight Conductive carbon black 15 parts by weight The resulting material pellets are extruded to a diameter of 150 m.
m, and immediately after extrusion, cooled and cut to a length of 270 mm to produce a seamless belt by continuous molding. Both sides of the back of this belt have a width of 10 mm and a thickness of 3
An intermediate transfer belt of Example 1 was prepared by attaching a rubber sheet for preventing meandering of mm.

This intermediate transfer belt has a thickness of 180 μm and a thickness of 2 μm.
% Elongation stress was 4.0 kgf / mm ² . The intermediate transfer belt was stretched around the electrophotographic apparatus shown in FIG. The tension at this time was 400 g / cm.

The image forming conditions are shown below.

As the toner, a non-magnetic one-component negatively chargeable toner was used for all four colors.

Photoconductor: OPC photosensitive drum First color primary transfer bias = +100 V Second color primary transfer bias = +650 V Third color primary transfer bias = +750 V Fourth color primary transfer bias = +750 V Secondary transfer current = 12 μA (constant current control) Transfer residual toner charging member is DC The component and the AC component were superimposed and applied.

When a full color image print test was performed using this apparatus, a good image without color shift was obtained. Thereafter, continuous color printing of 20,000 sheets was performed by this apparatus, and color misregistration was confirmed. As a result, good results were obtained without much difference from the initial state. Further, it was confirmed that there was no problem such as cutting or breakage of the intermediate transfer belt, and that the belt had sufficient durability.

Example 2 The following materials were melt-kneaded with a twin-screw extruder to produce material pellets.

Polyetherimide 100 parts by weight Conductive carbon black 16 parts by weight Using this material pellet, an intermediate transfer belt was produced in the same manner as in Example 1. However, the conditions for extrusion and cooling are not the same. (The same applies to the following examples and comparative examples.) The thickness of this intermediate transfer belt was 121 μm, and the stress when stretched by 2% was 4.8 kgf / mm ² .

The tension of the intermediate transfer belt was set to 500 g / c.
When the same print test was conducted by assembling the apparatus shown in FIG. 1 adjusted to m, good results were obtained without any problem both in the initial stage and after the endurance. Table 1 shows the results.

(Example 3) The following materials were melt-kneaded with a twin-screw extruder to produce material pellets.

Polyetheretherketone 100 parts by weight Conductive carbon black 16.5 parts by weight An intermediate transfer belt was prepared in the same manner as in Example 1 using the material pellets. The thickness of the intermediate transfer belt is 1
55 μm, and the stress at 2% elongation is 4.3 kgf / m
m ² .

The tension of the intermediate transfer belt is set to 800 g / c.
When the same print test was conducted by assembling in the same apparatus as in Example 1 adjusted to m, good results were obtained without any problem both in the initial stage and after the endurance. Table 1 shows the results.

Example 4 The following materials were melt-kneaded with a twin-screw extruder to produce material pellets.

Polyether sulfone 100 parts by weight Conductive carbon black 6 parts by weight An intermediate transfer belt was prepared in the same manner as in Example 1 using the material pellets. The thickness of the intermediate transfer belt is 2
02 μm, and the stress at 2% elongation is 3.8 kgf / m
m ² .

The tension of the intermediate transfer belt is set to 120 g / c.
When the same print test was conducted by assembling in the same apparatus as in Example 1 adjusted to m, no problem was found at the initial stage, but a slight color shift was observed after the endurance. Table 1 shows the results.

(Example 5) The following materials were melt-kneaded with a twin-screw extruder to produce material pellets.

100 parts by weight of polyarylate 7 parts by weight of conductive carbon black Using this material pellet, an intermediate transfer belt was prepared in the same manner as in Example 1. The thickness of the intermediate transfer belt 26
7 μm, and the stress at the time of 2% elongation is 3.2 kgf / mm.
^{Was 2} .

The tension of the intermediate transfer belt was set to 550 g / c.
When the same print test was conducted by assembling in the same apparatus as in Example 1 adjusted to m, good results were obtained without any problem both in the initial stage and after the endurance. Table 1 shows the results.

(Example 6) The following materials were melt-kneaded with a twin-screw extruder to produce material pellets.

Polyetherimide 100 parts by weight Conductive carbon black 3 parts by weight Using this material pellet, an intermediate transfer belt was formed by inflation molding. The thickness of this intermediate transfer belt 8
The stress at the time of 2% elongation is 5.0 kgf / mm.
^{Was 2} .

The tension of the intermediate transfer belt is set to 400 g / c.
When the same print test was conducted by assembling in the same apparatus as in Example 1 adjusted to m, good results were obtained without any problem both in the initial stage and after the endurance. Table 1 shows the results.

(Example 7) Using the material pellets of Example 1, an intermediate transfer belt having a reduced thickness was prepared by adjusting a mold during extrusion molding. The thickness of the intermediate transfer belt is 68 μm, and the stress at 2% elongation is 4.0.
kgf / mm ² .

The tension of the intermediate transfer belt was set to 300 g / c.
When the same print test was conducted by assembling in the same apparatus as in Example 1 adjusted to m, good results were obtained without any problem both in the initial stage and after the endurance. Table 1 shows the results.

[0065]

[Table 1]

Comparative Example 1 The following materials were melt-kneaded with a twin-screw extruder to produce material pellets.

100 parts by weight of FEP 6 parts by weight of conductive carbon black Using this material pellet, an intermediate transfer belt was produced in the same manner as in Example 1. However, the conditions for extrusion and cooling are not the same. The thickness of the intermediate transfer belt is 169 μm.
m and the stress at 2% elongation was 0.5 kgf / cm.

When this intermediate transfer member was assembled in the same apparatus as in Example 1 and a similar print test was performed, a slight color shift was recognized from the initial image, and the intermediate transfer belt was relaxed around 10,000 sheets of durability. A drop in tension resulted in slippage of the drive shaft and significant color shift. Table 2 shows the results.

(Comparative Example 2) A print test similar to that of Example 1 was performed using the intermediate transfer member of Example 1 and adjusting the distance between the axes of the apparatus to a tension of 50 g / cm. A slight color shift was recognized, and after the endurance, the color shift was particularly remarkable, and it was judged that it was not practical. Table 2 shows the results.

(Comparative Example 3) Using the intermediate transfer belt of Example 7, adjusting the center of the apparatus to adjust the tension to 1100 g / cm
When a print test was conducted, there was no problem in the initial stage, but after about 20,000 sheets after the endurance, the intermediate transfer belt was cracked, and it was judged that there was a problem in the durability. Table 2 shows the results.

[0071]

[Table 2]

[0072]

According to the present invention as described above,
Visualize the electrostatic latent image drawn on the latent image carrier with a developer,
The image forming apparatus that once transfers the obtained visible image onto the intermediate transfer body and then further transfers the image onto a transfer material is a belt-like intermediate transfer body of a thin film between a plurality of shafts.
An intermediate transfer unit having a mechanism for applying an electric field by directly contacting the intermediate transfer member with a tension of ~ 1000 g / cm;
gf / mm ² -8 kgf / mm ² and thickness 30 μm-30
It is characterized by being a seamless belt continuously formed of a 0 μm thermoplastic resin. With this configuration, high image quality,
An image forming apparatus of a resin intermediate transfer belt type which is low cost, has a long service life, and has improved maintainability can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a color image output device using an intermediate transfer belt.

FIG. 2 is a schematic diagram of a color image output apparatus using an intermediate transfer body electric field cleaning device.

FIG. 3 is a schematic diagram of an intermediate transfer belt tension measuring device.

[Explanation of symbols]

 Reference Signs List 1 photosensitive drum 2 primary charger 3 image exposure means 10 transfer material guide 11 paper feed roller 13 photosensitive drum cleaning device 15 fixing device 20 intermediate transfer belt 26 bias power supply 28 bias power supply 29 bias power supply 41 yellow developing device 42 magenta color Developing device 43 Cyan developing device 44 Black developing device 52 Transfer remaining toner charging member 62 Primary transfer roller 63 Secondary transfer roller 64 Secondary transfer facing roller 65 Intermediate transfer belt support roller 66 Intermediate transfer belt support roller (drive roller) 80 load cell P transfer material

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tsunetori Ashina 3- 30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Minoru Shimojo 3- 30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Atsushi Tanaka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Takashi Kusaba 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. F-term (reference) 2H032 AA05 AA15 BA09 BA23 BA30 CA04

Claims (8)

[Claims] An image forming apparatus for developing an electrostatic latent image drawn on a latent image carrier with a developer, transferring an obtained visible image to an intermediate transfer member once, and further transferring it to a transfer material. , An intermediate transfer unit having a mechanism in which a belt-like intermediate transfer body of a thin film is constantly stretched between a plurality of shafts at a tension of 100 g / cm to 1000 g / cm, and an electric field is applied by directly contacting the intermediate transfer body. Wherein the belt-shaped intermediate transfer member has a stress at the time of elongation of 2% of 2 kg.
f / mm ² -8 kgf / mm ² and thickness 30 μm-30
An image forming apparatus, which is a seamless belt continuously formed of a 0 μm thermoplastic resin. 2. The image forming apparatus according to claim 1, wherein the intermediate transfer body contains at least one of thermoplastic polyimide, polyetherimide, polyetheretherketone, polyethersulfone, polysulfone, and polyarylate. . 3. The image forming apparatus according to claim 1, wherein the electric field applied to the intermediate transfer member includes at least an AC electric field. 4. As a means for removing the developer remaining on the intermediate transfer member after transferring the image to the transfer material, a charge is applied to the residual developer by a charging member in contact with the intermediate transfer member,
The image forming apparatus according to any one of claims 1 to 3, further comprising a mechanism for removing a residual developer using an electric field at a collection site. 5. The image forming apparatus according to claim 4, wherein the removal of the residual developer from the intermediate transfer member and the transfer of the visible image formed on the photosensitive member are simultaneously performed. 6. The stress of the intermediate transfer member at the time of 2% elongation is 3%.
kgf / mm ² ~7kgf / mm ² or more in a claim 1
6. The image forming apparatus according to claim 5. 7. The belt according to claim 1, wherein the tension for stretching the intermediate transfer member is 300 g / cm to 800 g / cm.
7. The image forming apparatus according to claim 6. 8. The image forming apparatus according to claim 1, wherein a shaft on which the belt-shaped intermediate transfer member is stretched is fixed.