JP2001092270A - Electrostatic printing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate scattering of toner due to peeling discharge caused in the case of peeling paper from a transfer roller or the paper from an intermediate transfer belt in an electrostatic printing device. SOLUTION: The toner on the paper is welded before peeling discharge is caused between the paper and a transfer body (transfer roll, intermediate transfer belt or the like). For example, a paper 3 is wound around another rotating roller 8, so as to bring the paper surface where the toner 2 exists into contact with the roller 8 before the paper 3 is peeled from the transfer roller 6, and the toner is fixed by the time the paper is peeled from the roller 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic printing apparatus using an electrophotographic system, such as a copying machine and a printer, and more particularly to a technique for transferring and fixing a toner image.

[0002]

2. Description of the Related Art The electrophotographic system is one of the most well-known developing systems used for copying machines and printers. In a transfer section in a series of processes of the electrophotographic system, means using an electrostatic transfer system such as a corotron transfer system or a roller transfer system is mainly used.

However, when the electrostatic transfer method is used, a peeling discharge may be generated when the photosensitive member is peeled off from the paper or when the transfer roller is peeled off from the paper. When the peeling discharge occurs, the toner is scattered and the image quality is deteriorated. Such a phenomenon also occurs when the intermediate transfer member and the sheet are separated.

As a countermeasure against toner scattering due to peeling discharge, as shown in FIG. 2, immediately after the paper 3 separates from the photoreceptor 1, the paper 3 is brought into contact with a grounded paper transport guide 5, or as shown in FIG. The point at which the paper 3 and the transfer roller 6 are separated from each other is provided by applying a charge having a polarity opposite to that of the toner 2 by the corotron 7. However, these methods have limitations, and toner scattering exists to a small extent due to peeling discharge.

In Japanese Patent Laid-Open No. Hei 10-288899, two transfer rollers are used, one for pressure transfer, and the other for electrostatic transfer. By reducing the transfer electric field, toner scattering due to separation discharge between the paper and the transfer roller is less likely to occur. However, this method is also disclosed in
As stated in JP-A-88899, the only effect is that toner scattering due to peeling discharge hardly occurs.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is, in particular, to prevent toner from being scattered due to separation discharge generated when a transfer roller and a sheet are separated. The separation discharge that occurs when the sheet is separated is not limited to the separation between the transfer roller and the sheet, but also occurs when the sheet is separated from the intermediate transfer body (belt) on which the toner is primarily transferred and held. It is. An object of the present invention is to establish a technology that can cope with these problems.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic electrostatic printing apparatus which comprises the following steps: (1) fusing toner to a sheet before a transfer member such as a transfer roller or an intermediate transfer belt is separated from the sheet; Or (2) before the transfer body and the paper are separated, the paper is wound around a roller that rotates at the same speed as the paper, and a mechanism is provided to fuse the toner until the paper is peeled from the roller. it can.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram of an electrostatic printing apparatus according to a first embodiment of the present invention.

In this embodiment, the photosensitive member 1 is charged by the charger 21.
Is charged to a predetermined potential. Thereafter, an electrostatic latent image is formed on the photoconductor 1 by the exposure light source 11 based on the image information,
The developing device 12 develops the toner 2 on the photoconductor 1.
The toner 2 held on the photoconductor 1 is transferred onto the paper 3 by a transfer roller 6 to which a voltage having a polarity opposite to that of the toner is applied.

As shown in FIG. 4, the transfer roller 6 has a structure in which a conductive elastic body 15 is provided around a metal core 14 and the periphery thereof is covered with a heat-resistant tube 16. The roller hardness is 30 ° to 70 ° Asuka C, the volume resistivity is 10 ⁴ to 10 ⁸ Ωcm, and the roller is driven by the paper.

The conductive elastic body 15 is made of a rubber such as urethane, silicon, ethylene propylene diene rubber (EPDM) or a foam. Tube 16 is made of fluororesin, polyimide resin (PI), polyphenylene sulfide resin (PPS), polyetheretherketone resin (PEE)
K) and the like, the main component of which is a resin whose continuous use temperature exceeds 150 ° C.

In this embodiment, as a measure against the peeling discharge between the transfer roller 6 and the sheet 3, the method (2) of the solution means to be solved by the above invention is adopted.

That is, the sheet 3 onto which the toner 2 of the photoreceptor 1 has been transferred is wound around another roller 8 before the toner 3 is separated from the transfer roller 6. Roller 8
Is a heat roller that has a heat source 9 inside, is heated to the extent that the surface can fuse toner, and is driven by paper. The toner 2 is fused to the paper 3 by the heat roller 8.

After fusing the toner, the toner is transferred to the opposing roller 10.
Is fixed at the nip portion. Here, the outermost layer of the opposing roller is made of silicone rubber having a hardness of 40 ° to 50 ° as Asker C. As a substitute material of the silicone rubber, a fluorine resin, a polyimide resin (PI), a polyphenylene sulfide resin (PPS), a polyetheretherketone resin (PEEK), and the like can be considered.

In the configuration of the present embodiment, regarding the separation portion between the sheet 3 and the photosensitive member 1, the toner on the sheet 2 is attracted to the transfer roller 6, and the scattering of the toner in this portion is within an allowable range. Was. Further, at the separation portion between the sheet 3 and the transfer roller 6, the surface on which the toner 2 is held is in contact with the heat roller 8, so that the toner does not scatter. At the separation portion between the paper 3 and the heat roller 8, the toner 2 is already fixed on the paper 3, so that the toner does not scatter. The toner adhered to the heat roll 8 is cleaned (wiped) by the felt cleaner 22.

With the above configuration, the paper 3 onto which the toner 2 has been transferred is transferred to the heat roller 8 and the opposing roller 1 after the toner 2 is transferred.
0 until toner 2 is fixed on paper 3
The surface is the transfer roller 6, the heat roller 8, or the opposing roller 10.
And good image quality without toner scattering can be obtained. In this configuration, the opposing roller 10
It may be equipped with a heat source.

FIG. 5 relates to a second embodiment of the present invention.
This is a configuration in which the positions of the heat roller 8 and the opposing roller 10 shown in the first embodiment are interchanged.

Also in this embodiment, before the transfer roller 6 and the paper 3 are separated, the paper surface on which the toner 2 is transferred is wound around a roller 10 rotating at the same speed as the paper, and the paper is separated from the roller 10. By this time, the toner is fused (fixed) by the heat roller 8.

In this configuration, the paper contact time with the heat roll 8 is short, and the heating is performed from the surface (back surface) where there is no toner 2. Therefore, compared to the configuration shown in FIG. It is not suitable for high-speed machines because it is short and inefficient. As a countermeasure, a belt nip type fixing device as shown in the embodiment (third embodiment) of FIG. 6 is proposed.

By using a belt nip type fixing device, the fixing nip width can be increased. In FIG. 6, reference numeral 17 denotes a fixing belt made of a polyimide resin;
Reference numeral 8 denotes a support roller, which has a configuration in which the heat roller 8 is used as the support roller at the outlet of the paper 3, and can achieve image quality without fixing failure and toner scattering.

FIG. 7 relates to a fourth embodiment of the present invention. This embodiment relates to a technique for preventing toner scattering due to a discharge discharge between the intermediate transfer belt 20 and the sheet 3, and in particular, the above-mentioned invention is solved. Means (1) is adopted.

The intermediate transfer belt 20 temporarily transfers and holds the toner 2 visualized on the photoreceptor 1 onto the belt 20 before transferring the toner 2 onto the paper 3 by the transfer roll 6. The intermediate transfer belt 20 is made of, for example, a resin mainly composed of polyimide having excellent heat resistance, and is formed so as to have a volume resistivity of 10 ⁴ to 10 ¹⁵ Ωcm by containing carbon black.

The toner 2 held on the intermediate transfer belt 20 is transferred onto the paper 3 by the transfer roller 6 and the opposing roller 19 to which a voltage having a polarity opposite to that of the toner 2 is applied, and is transferred by the heating roller 8 and the opposing roller 10. After being fixed on the paper 3, the paper 3 is separated from the intermediate transfer belt 20. That is, since the toner 2 is fused to the sheet before the intermediate transfer belt 20 and the sheet 3 are separated, the toner is not scattered due to separation discharge when the intermediate transfer belt 20 and the sheet 3 are separated. Further, in this configuration, the positions of the opposing roller 10 and the heat roller 8 may be replaced, and a configuration in which a heat source is also mounted on the opposing roller 10 may be used. Further, the transfer mechanism may be a corotron transfer method.

FIG. 8 relates to a fifth embodiment of the present invention, which employs a technique of fusing toner to the paper 3 before the paper 3 and the transfer roller 6 are separated. .

That is, as shown in FIG. 8, after the paper 3 is separated from the photoreceptor 1, before the transfer roller 6 and the paper 3 are separated, a flash fixing device 23 is provided to fuse the toner 2 to the paper 3. Adopted a technique that would In the flash fixing, it is not necessary to completely fix the toner 2 on the paper 3, and it is only necessary to prevent toner scattering. Thereafter, the paper 3 is transported to the fixing device and is completely fixed, so that good image quality without toner scattering can be obtained. By providing a buffer 24 in the paper path for absorbing the speed difference between the fixing roll and the paper speed, the fixing roll does not need to be driven by the paper.

The present invention is particularly effective in a high-speed printer using continuous paper.

[0028]

As described above, according to the present invention, it is possible to prevent toner scattering due to peeling discharge between a transfer member of an electrostatic printing apparatus and a sheet, thereby improving image quality.

[Brief description of the drawings]

FIG. 1 is a configuration diagram according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of a transfer unit of a conventional electrostatic printing apparatus using a corotron transfer method.

FIG. 3 is a schematic diagram of a transfer unit of a conventional electrostatic printing apparatus using a roller transfer method.

FIG. 4 is a sectional view of a transfer roller.

FIG. 5 is a configuration diagram of an electrostatic printing apparatus according to a second embodiment of the present invention.

FIG. 6 is a configuration diagram of an electrostatic printing apparatus according to a third embodiment of the present invention.

FIG. 7 is a configuration diagram of an electrostatic printing apparatus according to a fourth embodiment of the present invention.

FIG. 8 is a configuration diagram of an electrostatic printing apparatus according to a fifth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photoconductor, 2 ... Toner, 3 ... Paper, 4 ... Corotron transfer device, 5 ... Paper conveyance guide, 6 ... Transfer roller, 7 ... Corotron charger, 8 ... Heat roller, 9 ... Heat source, 10 ... Opposing roller, 11 exposure source, 12 developing machine, 13 cleaning brush, 14 metal core, 15 conductive elastic body, 16 heat resistant tube, 17 fixing belt, 18 support roller,
19: opposing roller, 20: intermediate transfer belt, 21: charging device, 22: felt cleaner, 23: flash fixing device, 24: buffer.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H032 AA05 BA07 BA19 BA21 BA23 BA30 2H033 AA10 BA12 BB04 BB30 BB37 BC08

Claims (5)

[Claims] 1. A charged photoconductor is exposed to light based on image information to form an electrostatic latent image on the surface of the photoconductor, and the latent image is visualized with toner. An electrostatic printing apparatus for transferring to a sheet by a transfer method, comprising: a mechanism for fusing toner to the sheet before the sheet is separated from a transfer member such as a transfer roller and an intermediate transfer belt. apparatus. 2. A method according to claim 1, wherein the charged photoreceptor is exposed to light based on image information to form an electrostatic latent image on the surface of the photoreceptor, visualize the latent image with toner, and apply the developed toner to a roller. In an electrostatic printing apparatus that transfers to a sheet by a transfer method, before a transfer member such as a transfer roller or an intermediate transfer belt and the sheet are separated from each other, the sheet is wound around another roller that rotates at the same speed as the sheet. An electrostatic printing apparatus comprising a mechanism for fusing toner before paper is peeled off. 3. Another roller for winding the sheet before the transfer body and the sheet are separated from each other is driven by the sheet, and has another roller that comes into contact with the roller. The electrostatic printing apparatus according to claim 1, wherein at least one of the electrostatic printing apparatuses has a heat source therein. 4. The electrostatic printing apparatus according to claim 1, wherein the transfer member is a transfer roller, and the outermost horn layer is mainly composed of a resin whose continuous use temperature exceeds 150 ° C. 5. A mechanism for fusing toner on a sheet is a heat source for flash fixing located downstream of a section where the sheet and the photosensitive member are separated and upstream of a section where the transfer member and the sheet are separated. Item 3. The electrostatic printing device according to Item 1 or 2.