JPH0996972A - Electrophotographic device and electrophotographic transfer method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase transfer efficiency by allowing a transfer unit to come into contact with a toner image carrier only at the time of transferring, applying a transfer bias to a transfer material and heating toner up to a temperature higher than a glass- transition temp. and lower than a melting temp., in a device for performing a transfer from the toner image carrier having a specific size to the transfer material. SOLUTION: In the device using the toner image carrier having a diameter of >=60nm or a radius of curvature of >=30mm in a transfer part or a separating part, a toner composite image is carried to the transfer material 10, the transfer unit 14 comes into contact with an intermediate transfer body 18 and a voltage is applied to a charge roller 26 from a transfer belt 24 to charge it, and transferring the toner image on the intermediate transfer body 18 to the transfer material 10 all together. Simultaneously, the transfer material 10 is electrostatically attracted to the belt 24, separated from the intermediate transfer body 18. At this time, heat energy is applied to the toner from a roller 22 through the transfer belt 24, so that the toner is heated to a temp. higher than the glass-transition temp. and lower than the melting temp. In a fixing process, the toner image is fixed on the transfer material 10 by a fixing unit 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus such as a copying machine and a printer using electrophotographic technology and an electrophotographic transfer method.

[0002]

2. Description of the Related Art In recent years, output devices such as copying machines and printers have become widespread along with the automation of offices. In particular, electrophotographic devices are widely used because of their high resolution, high image quality, and high-speed printing capability.

A corona discharger has been widely used as a transfer device in an electrophotographic apparatus. However, the corona discharger needs to apply a high voltage of several kV or more, and has a problem that ozone is generated by the discharge. for that reason,
As an alternative technique, a transfer roller method for lowering voltage and ozone-less has been put into practical use.

In a conventional electrophotographic apparatus, a toner image bearing member, such as a photoconductor or an intermediate transfer member, generally has a diameter of 60 mm or less, or a radius of curvature of 30 mm or less at a transfer portion or a separation portion. After the transfer, the so-called curvature separation was possible due to the rigidity of the transfer material without providing a separating means.

On the other hand, in a color image forming apparatus in which toner images of respective colors are superposed on an intermediate transfer member, a toner image for one image has to be formed on a toner image carrier,
The circumference length of the toner image carrier must be longer than the image length. Therefore, the diameter of the intermediate transfer member is inevitably increased, and it becomes difficult to separate the transfer material due to its rigidity. Also,
In a color image forming apparatus, since a large amount of toner adheres to the intermediate transfer body in order to superpose colors, a large transfer current is required, and the transfer material is more likely to adhere to the intermediate transfer body. It becomes more difficult.

A conventional electrophotographic apparatus will be described below. FIG. 5 is a cross-sectional view of a conventional electrophotographic apparatus, and FIG. 6 is a cross-sectional view of essential parts around the transfer device. The latent image carrier 2 is arranged on the printer body 1 so as to be rotatable. Latent image carrier 2
On the surface of selenium (Se) or organic photoconductor (OP
C) etc. are coated. The diameter of the latent image carrier 2 is about 120 mm. Reference numeral 3 denotes a charger, which uniformly charges the latent image carrier 2 using corona discharge. Reference numeral 4 denotes an exposure optical system, which turns on and off a laser controlled by information from a host computer to form a latent image carrier 2.
An electrostatic latent image corresponding to a predetermined color component is formed thereon.
Reference numeral 5 denotes a developing device, which includes black (B), yellow (Y),
Color toners, which are developers of respective colors of magenta (M) and cyan (C), are housed and sequentially arranged around the latent image carrier 2 in a removable manner. Reference numeral 6 denotes a latent image carrier cleaner that removes toner remaining on the latent image carrier 2. Reference numeral 7 denotes a static eliminator provided with a light emitting diode and the like, which removes residual image charges remaining on the latent image carrier 2 by irradiating light after the residual toner is removed. As shown in FIG. 5, the latent image carrier 2
A charging device 3, an exposure optical system 4, a developing device 5, a latent image carrier cleaner 6, and a static eliminator 7 are arranged around.

Reference numeral 8 denotes an intermediate transfer member, which is arranged so as to contact the left side of the latent image carrier 2. The intermediate transfer body 8 has the same diameter as the latent image carrier 2. An intermediate transfer member cleaner 9 is disposed on the intermediate transfer member 8. 11 is a paper cassette, 12 is a paper feed roller, and the printer body 1
It is located underneath. 13 is a registration roller, 14
Is a transfer device, 15 is a separator, 16 is a conveyance guide, 17 is a fixing device, and 18 is a conveyance roller, and they are arranged on the left side of the intermediate transfer body 8. A paper discharge tray 19 is arranged above the printer body 1. The transfer device 14 is the transfer roller 2
0, and is apart from the intermediate transfer body 8 except during transfer.

The operation of the electrophotographic apparatus configured as described above will be described below. First, as a charging step, a corona discharge is performed in the charger 3 connected to the high-voltage power supply to uniformly charge the surface of the latent image carrier 2. next,
In the exposure step, the latent image carrier 2 is rotated in the direction of arrow A by a driving device to uniformly charge the surface of the latent image carrier 2 with a predetermined color of a plurality of color components, for example, black (B).
When an exposure light beam such as a laser beam corresponding to the image is irradiated, the irradiated part on the latent image carrier 2 loses its electric charge.
A latent image is formed. Next, as a developing step, the black developing device 5a containing a black developer contributing to the development is brought into contact with the latent image carrier 2 by a color selection signal from the host computer to develop the black toner. The developing device 5a for black having completed the development is moved again from the contact position with the latent image carrier 2 to the separation position. During development of the black developing device 5a, the other developing devices 5b, 5c and 5d are separated from the latent image carrier 2.

Next, for example, when the color of cyan (C) is selected, the developing device 5c for cyan is brought into contact with the latent image carrier 2 to start the development of cyan toner. The toner image formed on the latent image carrier 2 is sequentially transferred to the intermediate transfer member 8 for each color. Thereafter, the residual toner remaining on the latent image carrier 2 without being transferred is used as a cleaning process for the latent image carrier. The residual toner on the latent image carrier 2 is removed by the cleaner 6, and further, as a charge removing step, the residual electrostatic latent image on the latent image carrier 2 is removed by the charge remover 7, and the image forming step of one toner is completed. . In the case of a copier or printer using four colors, the above image forming process is sequentially repeated four times to form a toner composite image in which four color B, C, M, and Y toner images are superimposed on the intermediate transfer member 8. I do.

The toner composite image thus formed is subjected to a transfer bias of 750 on the transfer roller 20 as a transfer step.
The transfer material 10 is collectively transferred to the transfer material 10 by applying V. At this time, the transfer material 10 is charged and comes into close contact with the intermediate transfer body 8. Since the intermediate transfer member 8 has a diameter of 60 mm or more, the charged transfer material 1
0 cannot be curvature separated. Therefore, as a separation step, an AC bias of 14 kV is applied to the corona discharger wire of the separator 15.
The transfer material 10 is separated from the intermediate transfer member 8 by applying the voltage. Next, the transfer material 10 passes through the conveyance guide 16 and passes through the fixing device 1.
7. Next, as a fixing step, the toner image is fixed on the transfer material 10 by the fixing device 17, and then discharged onto the discharge tray 19.

[0011]

As described above, in a color image forming apparatus in which toner images of respective colors are superposed on an intermediate transfer member, a toner image for one image must be formed on the latent image carrier. However, it must be longer than the circumference of the latent image carrier. Therefore, the diameter of the intermediate transfer member is inevitably increased, and it becomes difficult to separate the transfer material due to its rigidity. Further, in the color image forming apparatus, since a large amount of toner adheres to the intermediate transfer body in order to superpose the colors, a large transfer current is required, and the transfer material is more easily attached to the intermediate transfer body. Separation becomes more difficult.

Therefore, in an electrophotographic apparatus using a toner image carrier having a diameter of 60 mm or more, or a radius of curvature of 30 mm or more at a transfer portion or a separation portion, an AC bias by corona discharge is generally used to separate the transfer material. However, there is a problem in that transfer efficiency is deteriorated due to toner scattering and reverse transfer to the toner image carrier.

The present invention is to solve the above-mentioned problems, and in an electrophotographic apparatus using a toner image carrier having a diameter of 60 mm or more or a radius of curvature of 30 mm or more at a transfer portion or a separation portion, toner scattering. It is an object of the present invention to provide an electrophotographic apparatus and an electrophotographic transfer method, in which transfer efficiency does not deteriorate due to reverse transfer to a toner image carrier.

[0014]

To achieve this object, the electrophotographic apparatus of the present invention uses a toner image having a diameter of 60 m.
An electrophotographic apparatus for transferring from a toner image carrier having a curvature radius of 30 mm or more at a transfer portion or a separation portion to a transfer material, wherein the transfer device contacts the toner image carrier only at the time of transfer. A transfer material is conveyed between the transfer material and a toner image carrier, and a transfer bias is applied when the toner image is transferred to the transfer material, and at the same time, the toner is heated above the glass transition temperature and below the melting temperature.

Further, the latent image carrier, process means such as charging, exposure, development, transfer, cleaning and charge removal disposed around the latent image carrier and the latent image carrier are brought into contact with each other to form a toner image. The diameter held at one end is 60 mm or more, or the radius of curvature at the transfer part or separation part is 30 mm
The intermediate transfer member serving as the toner image carrier described above, a transfer device that conveys a transfer material between the intermediate transfer member and the toner image, and a transfer device that transfers the toner image to the transfer material. An electrophotographic apparatus comprising a separator for separating from an image carrier surface and a fixing device for fixing the toner image onto a transfer material, wherein the transfer device contacts the intermediate transfer member only during transfer. The transfer material is conveyed between the intermediate transfer body and the transfer material, and a transfer bias is applied when the toner image is transferred to the transfer material, and at the same time, the toner is heated above the glass transition temperature and below the melting temperature.

[0016]

The present invention has a diameter of 60 mm due to the above construction.
In the above, or in the electrophotographic apparatus using the toner image carrier having a radius of curvature of 30 mm or more in the transfer portion or the separation portion, the transfer efficiency does not deteriorate due to toner scattering and reverse transfer to the toner image carrier.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an electrophotographic apparatus according to the first embodiment of the present invention, and FIG. 2 is a sectional view of a main part around the transfer device.

Reference numeral 2 is a latent image carrier, which is rotatably arranged on the printer body 1. The surface of the latent image carrier 2 is coated with a photosensitive receiving layer such as selenium (Se) or organic photoconductor (OPC). In addition, the latent image carrier 2
Has a diameter of about 120 mm. Reference numeral 3 denotes a charger, which uniformly charges the latent image carrier 2 using corona discharge. An exposure optical system 4 turns on / off a laser controlled by information from a host computer to form an electrostatic latent image corresponding to a predetermined color component on the latent image carrier 2. Reference numeral 5 denotes a developing device, which stores color toners that are developers of each color of black (B), yellow (Y), magenta (M), and cyan (C), and can be sequentially detached around the latent image carrier 2. It is located in. Reference numeral 6 denotes a latent image carrier cleaner that removes toner remaining on the latent image carrier 2. Reference numeral 7 denotes a static eliminator provided with a light emitting diode and the like, which removes residual image charges remaining on the latent image carrier 2 by irradiating light after the residual toner is removed. Similar to FIG. 5, a charging device 3, an exposure optical system 4, a developing device 5, a latent image carrier cleaner 6, and a charge eliminator 7 are arranged around the latent image carrier 2.

Reference numeral 8 denotes an intermediate transfer member, which is arranged so as to contact the left side of the latent image carrier 2. The intermediate transfer body 8 has the same diameter as the latent image carrier 2. An intermediate transfer member cleaner 9 is disposed on the intermediate transfer member 8. 11 is a paper cassette, 12 is a paper feed roller, and the printer body 1
It is located underneath. 13 is a registration roller, 14
Is a transfer device, 15 is a separator, 16 is a conveyance guide, 17 is a fixing device, and 18 is a conveyance roller, and they are arranged on the left side of the intermediate transfer body 8. A paper discharge tray 19 is arranged above the printer body 1. The transfer device 14 is a transfer roller having a heat source 21, and is separated from the intermediate transfer body 8 except during transfer.

The operation of the electrophotographic apparatus configured as described above will be described below. First, as a charging step, a corona discharge is performed in the charger 3 connected to the high-voltage power supply to uniformly charge the surface of the latent image carrier 2. Next, as an exposure step, the latent image carrier 2 is rotated in the direction of arrow A by a driving device, and a predetermined color of a plurality of color components, for example, black (B) is applied to the surface of the uniformly charged latent image carrier 2. When an exposure light beam such as a laser beam corresponding to the image is irradiated, the irradiated portion on the latent image carrier 2 loses its charge, and a latent image is formed. Next, as a developing step, the black developing device 5a containing a black developer contributing to the development is brought into contact with the latent image carrier 2 by a color selection signal from the host computer to develop the black toner.
The developing device 5a for black having completed the development is moved again from the contact position with the latent image carrier 2 to the separation position. During development of the black developing device 5a, other developing devices 5b, 5c, 5
d is separated from the latent image carrier 2. Next, for example, when the color of cyan (C) is selected, the cyan developing device 5d is brought into contact with the latent image carrier 2 to start the development of cyan toner.
The toner image formed on the latent image carrier 2 is sequentially transferred to the intermediate transfer member 8 for each color. Thereafter, the residual toner remaining on the latent image carrier 2 without being transferred is used as a cleaning process for the latent image carrier. The residual toner on the latent image carrier 2 is removed by the cleaner 6, and further, as a charge removing step, the residual electrostatic latent image on the latent image carrier 2 is removed by the charge remover 7, and the image forming step of one toner is completed. . In the case of a copying machine or printer using four colors, the above-mentioned image forming process is sequentially repeated four times, and four colors B, C, M and Y are formed on the intermediate transfer body 8.
A toner composite image is formed by superimposing the toner images of.

The toner composite image thus formed is transferred in a batch to the transfer material 10 by applying a transfer bias of 750 V to the transfer device 14 having the heat source 21 as a transfer step, and at the same time, thermal energy is applied from the transfer roller 21. The toner is heated above the glass transition temperature and below the melting temperature. Next, as a separation step, an AC bias of 14 kV was applied to the wire of the corona discharger of the separator 15 to apply the intermediate transfer member 8
The transfer material 10 is separated from. Next, the transfer material 10 passes through the transport guide 16 and is transported to the fixing device 17. next,
As a fixing step, the toner image is transferred onto the transfer material 1 by the fixing device 17.
It is fixed at 0, and then discharged to the discharge tray 19.

As described above, according to the electrophotographic apparatus of the first embodiment of the present invention, since the toner is fixed to the transfer material by applying heat to the toner at the same time as the transfer, the AC bias is applied to the transfer material. Even if the toner is separated from the intermediate transfer member, the transfer efficiency does not deteriorate due to the scattering of the toner and the reverse transfer to the image carrier. The reason why the toner is not heated above the melting temperature is to prevent the intermediate transfer member from being overheated so that the transfer efficiency from the latent image carrier is deteriorated, and the toner is transferred to the intermediate transfer member to deteriorate the image. This is to prevent this. Also, the reason for not heating below the glass transition temperature is
This is because the toner is not fixed on the transfer material. Moreover, since the intermediate transfer member is contacted only during transfer, heat does not affect the intermediate transfer member.

Next, a second embodiment of the present invention will be described. FIG. 3 is a cross-sectional view of the main part around the transfer device of the electrophotographic apparatus in the second embodiment of the present invention. The sectional view of the electrophotographic apparatus in the second embodiment is the same as that in FIG. 1 except for the transfer and separator. Reference numeral 2 denotes a latent image carrier, which is arranged on the printer body 1 so as to be rotatable. The surface of the latent image carrier 2 is coated with a photosensitive receiving layer such as selenium (Se) or organic photoconductor (OPC). The diameter of the latent image carrier 2 is about 120 mm. Reference numeral 3 denotes a charger, which uniformly charges the latent image carrier 2 using corona discharge. An exposure optical system 4 turns on / off a laser controlled by information from a host computer to form an electrostatic latent image corresponding to a predetermined color component on the latent image carrier 2. Reference numeral 5 denotes a developing device, which stores color toners that are developers of each color of black (B), yellow (Y), magenta (M), and cyan (C), and can be sequentially detached around the latent image carrier 2. It is located in. Reference numeral 6 denotes a latent image carrier cleaner that removes toner remaining on the latent image carrier 2. Reference numeral 7 denotes a static eliminator provided with a light emitting diode and the like, which removes residual image charges remaining on the latent image carrier 2 by irradiating light after the residual toner is removed. As shown in FIG. 5, a charging device 3, an exposure optical system 4, a developing device 5, a latent image carrier cleaner 6, and a charge eliminator 7 are arranged around the latent image carrier 2.

Reference numeral 8 denotes an intermediate transfer member, which is arranged so as to contact the left side of the latent image carrier 2. The intermediate transfer body 8 has the same diameter as the latent image carrier 2. An intermediate transfer member cleaner 9 is disposed on the intermediate transfer member 8. 11 is a paper cassette, 12 is a paper feed roller, and the printer body 1
It is located underneath. 13 is a registration roller, 14
Is a transfer device, 17 is a fixing device, and 18 is a conveying roller, which are arranged on the left side of the intermediate transfer member 8. A paper discharge tray 19 is arranged above the printer body 1. In the transfer device 14, a transfer belt 24 is wound around a roller 22 having a heat source and a rotating roller 23, and the intermediate transfer member 8 in the transfer belt 24 is wound.
A transfer charger 25 that charges the transfer belt 24 is disposed on the side facing the. The transfer device 14 is apart from the intermediate transfer member 8 except during transfer.

The operation of the electrophotographic apparatus of the second embodiment constructed as above will be described below. 4 colors B are formed on the intermediate transfer member 8 through the same steps as in the first embodiment.
A toner composite image is formed by superimposing C, M, and Y toner images. In the transfer step, the toner composite image formed in this manner is conveyed to the transfer material 10, and the transfer device 14 contacts the intermediate transfer member 8 to apply 4 kV from the back surface of the transfer belt 24 to the wire of the transfer charger. By applying a voltage to perform corona discharge and charging the transfer belt 24, the toner images on the intermediate transfer body 8 are collectively transferred to the transfer material 10, and at the same time, the transfer material 1 is transferred.
Since 0 is electrostatically attracted to the transfer belt 24 by electrostatic polarization, the transfer material 10 is separated from the intermediate transfer body 8. At this time, heat energy is applied to the toner from the roller 22 having a heat source through the transfer belt 24 to heat the toner above the glass transition temperature and below the melting temperature. Next, the transfer material 10 passes over the transfer belt 24 and is conveyed to the fixing device 17. Next, as a fixing step, the toner image is fixed on the transfer material 10 by the fixing device 17, and then discharged onto the discharge tray 19.

As described above, according to the electrophotographic apparatus of the second embodiment of the present invention, since the toner is fixed to the transfer material by applying heat to the toner at the same time as the transfer, the transfer material is separated from the intermediate transfer body. There is no deterioration of transfer efficiency due to toner scattering or reverse transfer to the toner image carrier due to electric discharge generated when the transfer material is separated from the transfer belt.

The reason why the toner is not heated above the melting temperature is that the intermediate transfer member is prevented from being overheated and the transfer efficiency of the latent image carrier is prevented from being deteriorated, and the toner is transferred to the intermediate transfer member to form an image. This is to prevent the deterioration of. Also, the reason for not heating below the glass transition temperature is
This is because the toner is not fixed on the transfer material. Moreover, since the intermediate transfer member is contacted only during transfer, heat does not affect the intermediate transfer member. Further, the transport guide can be omitted, and a high voltage power source such as a separator based on AC bias is not required.

Next, a third embodiment of the present invention will be described. FIG. 4 is a cross-sectional view of the main part around the transfer device of the electrophotographic apparatus in the third embodiment of the present invention. The sectional view of the electrophotographic apparatus in the third embodiment is the same as that in FIG. Reference numeral 2 denotes a latent image carrier, which is arranged on the printer body 1 so as to be rotatable. The surface of the latent image carrier 2 is coated with a photosensitive receiving layer such as selenium (Se) or organic photoconductor (OPC). The diameter of the latent image carrier 2 is about 120 mm. Reference numeral 3 denotes a charger, which uniformly charges the latent image carrier 2 using corona discharge. An exposure optical system 4 turns on / off a laser controlled by information from a host computer to form an electrostatic latent image corresponding to a predetermined color component on the latent image carrier 2. A developing device 5 stores color toners that are developers of black (B), yellow (Y), magenta (M), and cyan (C), and can be sequentially detached around the latent image carrier 2. It is located in. Reference numeral 6 denotes a latent image carrier cleaner that removes toner remaining on the latent image carrier 2. Reference numeral 7 denotes a static eliminator provided with a light emitting diode and the like, which removes residual image charges remaining on the latent image carrier 2 by irradiating light after the residual toner is removed. As shown in FIG. 5, a charging device 3, an exposure optical system 4, a developing device 5, a latent image carrier cleaner 6, and a charge eliminator 7 are arranged around the latent image carrier 2.

Reference numeral 8 denotes an intermediate transfer member, which is arranged so as to contact the left side of the latent image carrier 2. The intermediate transfer body 8 has the same diameter as the latent image carrier 2. An intermediate transfer member cleaner 9 is disposed on the intermediate transfer member 8. 11 is a paper cassette, 12 is a paper feed roller, and the printer body 1
It is located underneath. 13 is a registration roller, 14
Is a transfer device, 17 is a fixing device, and 18 is a conveying roller, which are arranged on the left side of the intermediate transfer member 8. A paper discharge tray 19 is arranged above the printer body 1. In the transfer device 14, a transfer belt 24 is wound around a roller 22 having a heat source 21 and a rotating roller 23, and a charging roller that contacts the transfer belt 24 and applies a voltage to the side of the transfer belt 24 facing the intermediate transfer body 8. 26 are arranged. The transfer device 14 is separated from the intermediate transfer body 8 except during transfer.

The operation of the electrophotographic apparatus of the third embodiment constructed as described above will be described below. After the same steps as those in the first embodiment, four colors B,
A toner composite image is formed by superimposing C, M, and Y toner images. In the transfer process, the toner composite image formed in this manner is conveyed to the transfer material 10, the transfer device 14 contacts the intermediate transfer member 8, and a voltage of 4 kV is applied to the charging roller from the back surface of the transfer belt 24. Then, by charging the transfer belt 24, the toner images on the intermediate transfer body 8 are collectively transferred to the transfer material 10, and at the same time, the transfer material 10 is electrostatically attracted to the transfer belt 24 by electrostatic polarization. Is the intermediate transfer member 8
Separated from. At this time, the roller 2 having a heat source
Heat energy from 2 is applied to the toner through the transfer belt 24 to heat the toner above the glass transition temperature and below the melting temperature. Next, the transfer material 10 is transferred onto the transfer belt 24.
After passing over, it is conveyed to the fixing device 17. Next, as a fixing step, the toner image is fixed on the transfer material 10 by the fixing device 17, and then discharged onto the discharge tray 19.

As described above, according to the electrophotographic apparatus of the third embodiment of the present invention, since the toner is fixed to the transfer material by applying heat to the toner at the same time as the transfer, the transfer material is separated from the intermediate transfer body. Also, there is no deterioration of transfer efficiency due to toner scattering or reverse transfer to the image carrier due to electric discharge generated when the transfer material is separated from the transfer belt.

The reason why the toner is not heated above the melting temperature is to prevent the intermediate transfer member from being overheated and the transfer efficiency from being deteriorated from the latent image carrier and to prevent the toner from being transferred to the intermediate transfer member. This is to prevent the deterioration of. Also, the reason for not heating below the glass transition temperature is
This is because the toner is not fixed on the transfer material. Further, in the third embodiment as well, the intermediate transfer member is brought into contact only during transfer, so that heat does not affect the intermediate transfer member. Further, the transport guide can be omitted, and a high voltage power source such as a separator based on AC bias is not required. Moreover, since there is no corona discharger, ozone is not generated.

[0033]

As described above, the present invention has a diameter of 60 mm.
In the above, or in the electrophotographic apparatus using the toner image carrier having a radius of curvature of 30 mm or more in the transfer portion or the separation portion, the transfer efficiency does not deteriorate due to toner scattering and reverse transfer to the toner image carrier. Therefore, since the latent image on the latent image carrier is basically not destroyed, the same clear toner image can be formed on the transfer material by developing the latent image with good reproducibility. Therefore, a highly reliable electrophotographic device can be realized.

Further, in the conventional electrophotographic apparatus, when the process speed is increased for high-speed printing, it is necessary to further increase the applied voltage when separating the transfer material from the toner image carrier, so that the toner is scattered. The transfer efficiency by reverse transfer to the toner image carrier is further deteriorated, but in the present invention, since the scattering of toner and the deterioration of transfer efficiency due to reverse transfer to the toner image carrier do not occur, electrophotographic apparatuses for high-speed printing are also applicable. Can be realized.

[Brief description of drawings]

FIG. 1 is a sectional view of an electrophotographic apparatus according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of essential parts around a transfer device of an electrophotographic apparatus in a first embodiment of the present invention.

FIG. 3 is a cross-sectional view of essential parts around a transfer device of an electrophotographic apparatus according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view of a main portion around a transfer device of an electrophotographic apparatus according to a third embodiment of the present invention.

FIG. 5 is a sectional view of a conventional electrophotographic apparatus.

FIG. 6 is a sectional view of a main part around a transfer device of a conventional electrophotographic apparatus.

[Explanation of symbols]

 1 Printer Main Body 2 Latent Image Carrier 3 Charging Device 4 Exposure Optical System 5 Developer 6 Latent Image Carrier Cleaner 7 Electrifier 8 Intermediate Transfer Body 9 Intermediate Transfer Body Cleaner 10 Transfer Material 11 Paper Cassette 12 Paper Feed Roller 13 Resist Roller 14 Transfer device 15 Separator 16 Conveying guide 17 Fixing device 18 Conveying roller 19 Paper ejection tray 20 Transfer roller 21 Heat source 22 Roller with heat source 23 Rotating roller 24 Transfer belt 25 Transfer charger 26 Charging roller

Claims (7)

[Claims] 1. An electrophotographic apparatus for transferring a toner image onto a transfer material from a toner image carrier having a diameter of 60 mm or more or a radius of curvature of 30 mm or more at a transfer portion or a separation portion, wherein a transfer device is used only during transfer. The transfer material is brought into contact with the toner image carrier and the transfer material is conveyed to and from the toner image carrier, and a transfer bias is applied when the toner image is transferred to the transfer material, and at the same time, the toner is higher than the glass transition temperature, An electrophotographic apparatus characterized by being heated below the melting temperature. 2. A latent image carrier, process means such as charging, exposure, development, transfer, cleaning and charge removal arranged around the latent image carrier, and a toner image contacting the latent image carrier. The intermediate transfer member serving as a toner image carrier having a diameter of 60 mm or more for holding one end or a curvature radius of 30 mm or more at a transfer portion or a separation portion, and a transfer material is conveyed between the intermediate transfer member and the transfer material. An electrophotographic apparatus including a transfer device for transferring the toner image, a separator for separating the transfer material on which the toner image is transferred from the surface of the latent image carrier, and a fixing device for fixing the transfer material on which the toner image is transferred. An apparatus, in which the transfer device contacts the intermediate transfer member only during transfer, conveys a transfer material to and from the intermediate transfer member, and applies a transfer bias when transferring the toner image to the transfer material. And at the same time Electrophotographic apparatus characterized by heating the toner above the glass transition temperature, and lower than the melting temperature. 3. The electrophotographic apparatus according to claim 2, wherein the transfer device is a roller-shaped rotating body and has a heat source. 4. The electrophotographic apparatus according to claim 2, wherein the transfer device is a belt-shaped rotating body and has a heat source. 5. The electronic device according to claim 4, wherein the transfer device has a belt wound around a roller having a heat source and a rotating roller, and a charging device is arranged on the surface of the belt facing the intermediate transfer member. Photographic equipment. 6. The transfer device has a belt wound around a roller having a heat source and a rotating roller, and a roller for applying a voltage is arranged on the side of the belt facing the intermediate transfer member so as to be in contact with the belt. The electrophotographic apparatus according to claim 4, which is characterized in that. 7. A transfer device is in contact with a toner image carrier that carries a toner image only during transfer, conveys a transfer material between the transfer device and the toner image carrier, and transfers the toner image onto the transfer material. A method for transferring electrophotography, which comprises applying a bias and simultaneously heating the toner above a glass transition temperature and below a melting temperature.