JP2002258627A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of reducing the splashing of untransferred toner caused by the change of electric field and preventing electrostatic offset in a fixing stage. SOLUTION: In this image forming device where a toner image formed on a photoreceptor 1 is electrostatically transferred to a transfer paper sheet on a transfer belt 2, the transfer paper sheet is made to advance directly to a fixing roller 6 from the belt 2, and destaticizing mechanisms 9 and 10 are provided in the belt 2 and the roller 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile, and the like.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a printer, and a facsimile, a transfer sheet is transported from a transfer apparatus to a fixing apparatus while an unfixed toner image is placed on the transfer sheet. However, when transferring from the photoreceptor to the transfer paper, a large amount of electric charge is placed on the back of the transfer paper because the transfer is performed by applying a charge having the opposite polarity to the toner to the back of the transfer paper. Therefore,
Charges of different polarities are on both sides of the transfer paper. On the other hand, when the toner enters between the fixing roller and the pressure roller of the fixing device, it hits one of the rollers, so that an impact is applied to the transfer paper and the unfixed toner image may be scattered.
Further, since the unfixed toner image has electric charges, an electric suction force or a repulsive force may act between the unfixed toner image and the charged roller due to friction between the rollers. For this reason, the inside of the image forming apparatus may be contaminated by toner scattering due to the unfixed toner image on the transfer paper conveyed from the transfer apparatus to the fixing apparatus.

Accordingly, for example, Japanese Patent Application Laid-Open No. 6-230683 describes
Japanese Patent Application Laid-Open No. 8-248778 discloses an image forming apparatus which does not scatter toner in a space or disturbs an image arrangement. Japanese Patent Application Laid-Open No. 7-230220 discloses an image forming apparatus using a belt transfer system, which prevents toner scattering at the time of transfer and before and after transfer, prevents the formation of a filming layer on the belt surface, prevents contamination in the device,
2. Description of the Related Art An image forming apparatus has been proposed which prevents a heating roller and a backup roller of a fixing machine from being stained. Further, for example, Japanese Patent Application Laid-Open No. 7-64421 proposes an image forming apparatus that suppresses a thermal effect on a transfer belt by a heat fixing device and reliably conveys transfer paper to a fixing device.

[0004]

However, the belt transfer method has been generally used in recent years because the amount of generated ozone is extremely small as compared with the corona charge transfer method, and the paper can be easily transported by the belt. The toner image formed on the surface of the photoreceptor is transferred to a transfer paper on a belt, and then conveyed to a fixing device where the toner image is completely fixed by pressing and heating the roller. Since the unfixed toner immediately after the transfer is only electrostatically attached by the electric charge applied from the back surface of the transfer belt, the change in the electric field causes the image to be disturbed. That is, since unfixed toner is scattered between the transfer belt and the fixing roller, the final image quality is significantly deteriorated.

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide an image forming apparatus capable of reducing scattering of untransferred toner due to electric field change and preventing electrostatic offset in a fixing process.

[0006]

According to the first aspect of the present invention, there is provided an image forming apparatus for electrostatically transferring a toner image formed on a photoreceptor to transfer paper on a transfer belt. In the image forming apparatus, an image forming apparatus is provided in which a transfer sheet directly enters a transfer roller from a transfer belt to a fixing roller, and a charge removing mechanism is provided on the transfer belt and the fixing roller. Claim 2
The invention according to claim 1 is the image forming apparatus according to claim 1, wherein an intermediate conveyance belt is used between the transfer belt and the fixing roller. According to a third aspect of the present invention, there is provided the image forming apparatus according to the first aspect, wherein an intermediate conveyance roller is provided between the transfer belt and the fixing roller. According to a fourth aspect of the present invention, there is provided the image forming apparatus according to the second or third aspect, wherein the intermediate transport belt or the intermediate transport roller is 10 ⁸ to 10 ¹² Ωcm and is grounded.
According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, A is used as the charge removing mechanism.
An image forming apparatus using a C neutralization charger. According to a sixth aspect of the present invention, there is provided the image forming apparatus according to any one of the first to fifth aspects, wherein at least the fixing roller is provided with a charge removing mechanism.
According to a seventh aspect of the present invention, there is provided the image forming apparatus according to any one of the first to sixth aspects, wherein the charge eliminating mechanism extends over both the transfer belt and the fixing roller.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic side view showing the configuration of the image forming apparatus. The toner image formed on the photoconductor drum 1 is transferred onto a transfer sheet conveyed on a transfer belt 2. The transfer paper carrying the unfixed toner is conveyed to the fixing roller 6 by the transfer belt 2, but toner scattering occurs between the transfer belt 2 and the fixing roller 6. The transfer paper peeled off from the belt at the transfer outlet passes over the guide plates 7 and 8, but unfixed toner on the transfer paper is easily scattered at that time. Further, when the transfer sheet enters the fixing roller 6, the toner is scattered before the toner is fixed at the nip of the roller due to the charging potential of the roller surface. This phenomenon is called an electrostatic offset.

FIG. 2 is a schematic side view showing the structure of an image forming apparatus provided with a charge eliminating mechanism between a transfer belt and a fixing roller. The transfer paper on which the unfixed toner is placed is directly conveyed from the transfer belt 2 to the fixing roller 6, and a static elimination mechanism 10 (here, a static elimination charger is taken as an example) is provided to prevent electrostatic offset of the fixing roller 6. Is the feature. Another static elimination mechanism 9 (here, a static elimination charger as an example) provided at the transfer outlet functions to peel the transfer paper from the belt. Thereby, the transfer belt 2
And the fixing roller 6 can be eliminated.

FIG. 3 is a schematic side view showing the configuration of an image forming apparatus provided with an intermediate conveyance belt. FIG. 4 is a schematic side view illustrating a configuration of an image forming apparatus provided with an intermediate conveyance roller. For toner scattering, it is advantageous that the intermediate conveyance belt and the intermediate conveyance roller have medium resistance conductivity and are electrically grounded. ¹⁰ is a medium resistance at this time ^{8-10 1 2}
Ωcm. At this time, a static elimination mechanism 10 is provided to prevent electrostatic offset of the fixing roller 6.

FIG. 5 is a schematic side view showing the structure of an image forming apparatus provided with a charge removing mechanism near the fixing roller. As described above, the static elimination mechanism 10 provided on the surface of the fixing roller 6 can prevent electrostatic offset. Since the charge removal mechanism 9 at the transfer outlet is provided for facilitating the peeling of the transfer paper, the transfer may be performed when a device for facilitating the peeling of the transfer paper is reduced, for example, by providing a peeling claw on the transfer belt 2. The discharge mechanism 9 at the exit becomes unnecessary.

FIG. 6 is a schematic side view showing the structure of an image forming apparatus provided with one charge eliminating mechanism between the transfer belt and the fixing roller. The static elimination of both the fixing roller 6 and the transfer outlet may be performed by one static elimination charger.

[0012]

As described above, in the image forming apparatus of the present invention, the scattering of unfixed toner on the transfer paper can be suppressed, and the final image quality can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic side view illustrating a configuration of an image forming apparatus.

FIG. 2 is a schematic side view illustrating a configuration of an image forming apparatus provided with a charge removing mechanism between a transfer belt and a fixing roller.

FIG. 3 is a schematic side view illustrating a configuration of an image forming apparatus provided with an intermediate conveyance belt.

FIG. 4 is a schematic side view illustrating a configuration of an image forming apparatus provided with an intermediate conveyance roller.

FIG. 5 is a schematic side view illustrating a configuration of an image forming apparatus provided with a charge removing mechanism near a fixing roller.

FIG. 6 is a schematic side view showing a configuration of an image forming apparatus provided with one electricity removing mechanism between a transfer belt and a fixing roller.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photosensitive drum 2 transfer belt 3 drive roller 4 driven roller 5 bias roller 6 fixing roller 7 fixing entrance guide plate 8 transfer exit guide plate 9 static elimination charger on transfer belt surface 10 static elimination charger on transfer roller surface 11 intermediate transport belt 12 drive roller 13 driven roller 14 intermediate transport roller 15 static elimination charger

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/20 102 G03G 15/20 102

Claims (7)

[Claims] 1. An image forming apparatus for electrostatically transferring a toner image formed on a photoreceptor onto a transfer sheet on a transfer belt, wherein the transfer sheet directly enters the fixing roller from the transfer belt, and the transfer belt and the fixing device are fixed. An image forming apparatus, wherein a roller is provided with a charge removing mechanism. 2. The image forming apparatus according to claim 1, wherein an intermediate conveyance belt is used between the transfer belt and the fixing roller. 3. The image forming apparatus according to claim 1, wherein an intermediate conveyance roller is used between the transfer belt and the fixing roller. 4. The image forming apparatus according to claim 2, wherein the intermediate transport belt or the intermediate transport roller has a width of 10 ⁸ to 10 ^12.
An image forming apparatus, which is Ωcm and grounded. 5. The image forming apparatus according to claim 1, wherein an AC charge removing device is used as the charge removing mechanism. 6. The image forming apparatus according to claim 1, wherein at least a fixing roller is provided with a charge removing mechanism. 7. The image forming apparatus according to claim 1, wherein the charge eliminating mechanism extends over both the transfer belt and the fixing roller.