JPH0728337A - Transfer device - Google Patents

Abstract

PURPOSE:To provide a transfer device which stabilizes a transferred image and prevents paper from being wrapped round a photoreceptor. CONSTITUTION:The device is composed of a shield case 11 where an opening 10, opposite the photoreceptor 1 on which a toner image is formed, is made on one side and a corona discharging body 12 is provided inside; a nonconductive paper-guide 13 extending from the inside of the opening 10 of the shield case 11 to a fixing unit 9; a plurality of ribs 14 projecting from one side of the paper guide 13, on the side of the photoreceptor 1; and a metal plate 15 which is made of a material having thickness smaller than the length of the ribs 14, is disposed between the ribs, and is given potential whose polarity is different from that given to the paper 7 by the corona discharging body 12. A transferred toner image is stabilized by peeling the paper 7 off the photoreceptor 1 by means of the metal plate 15, and separating the paper 7 from the metal plate 15 by means of the ribs 14, thereby maintaining the potential of the paper 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer device for transferring a toner image formed on the outer periphery of a photoconductor to a sheet.

[0002]

2. Description of the Related Art First, FIG. 3 shows a conventional example. Reference numeral 1 is a photoconductor. A charger 2, an exposure unit (not shown), a developing unit 3, a transfer unit 4, and a cleaning unit 5 are arranged on the outer periphery of the photoconductor 1. Photoconductor 1 and transfer device 4
A paper conveyance path 6 passing between the paper and paper is provided with a conveyance roller 8 for conveying the paper 7 and a fixing device 9. Transfer device 4
Has a shield case 11 in which an opening 10 facing the photoconductor 1 is formed, and a corona discharge wire 12 which is a corona discharge body stretched inside the shield case 11, and the opening of the shield case 11 is formed. The section 10 is provided with a sheet guide 13 made of synthetic resin and extending from the inside of the opening 10 toward the fixing device 9.

Next, the operation will be described by taking the case of regular development as an example. When a positive voltage is applied to the charger 2, a positive potential is applied to the outer circumference of the photoconductor 1. Then, by partially exposing the charged portion of the photoconductor 1 by the exposing portion, the unexposed portion remains as an electrostatic latent image having a positive potential. The toner charged to a negative potential is attracted from the developing device 3 to an electrostatic latent image having a positive potential. That is,
A toner image is formed on the photoconductor 1.

On the other hand, when the paper 7 is fed by the conveying roller 8 in synchronization with the rotational movement of the photoconductor 1 and a positive potential is applied to the paper 7 from the corona discharge wire 12 of the transfer unit 4, the photoconductor 1 is moved. The negatively charged toner image is attracted to the paper 7 having a positive potential. That is, the toner image on the photoconductor 1 is transferred to the paper 7. The sheet 7 is conveyed to the fixing device 9 and fixed. In this case, the paper guide 13 has a function of preventing the leading end of the paper 7 from entering the inside of the shield case 11 of the transfer device 4 and guiding it to the fixing device 9 side. If the potential applied to the paper 7 escapes to the other via the paper guide 13, the toner transferred on the paper 7 becomes unstable and moves, so that the paper guide 13 directly supporting the paper 7 is made of a non-conductive material such as synthetic resin. It is made of a flexible material. The residual toner remaining on the outer periphery of the photoconductor 1 after the transfer is wiped by the blade 5a of the cleaning unit 5.

[0005]

Since the negative toner image on the photoconductor 1 and the paper 7 to which the positive potential is applied are attracted to each other, the paper 7 is wound around the photoconductor 1 and a jam occurs. There is a risk.

[0006]

SUMMARY OF THE INVENTION According to the present invention, there is provided a shield case in which an opening facing a photoconductor on which a toner image is formed is formed on one surface and a corona discharge body is provided therein, and the opening of the shield case. A non-conductive paper guide extending from the inside of the portion to the fixing device side, a plurality of ribs projecting from one surface of the paper guide on the photoconductor side, and a material thinner than the height of these ribs. And a metal plate which is disposed between the ribs and which is provided with a potential having a polarity different from that of the potential applied to the paper from the corona discharge body.

[0007]

Since different potentials are applied to the metal plate and the paper, the paper can be sucked by the metal plate and quickly separated from the photoconductor. In addition, since the paper supported by the ribs does not contact the metal plate, it is possible to avoid the state in which the electric potential applied to the paper for transfer escapes to the other, so that the toner image transferred on the paper is prevented. Can be stabilized.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. The same parts as those described with reference to FIG. The opening 10 of the shield case 11 of the transfer device 4 is provided with a paper guide 13 made of synthetic resin and extending from the inside of the opening 10 toward the fixing device 9. A plurality of ribs 14 are formed on one surface of the paper guide 13 facing the photoconductor 1.
A metal plate 15 is provided between them.

As shown in FIG. 2, the shape of the rib 14 is long in the direction orthogonal to the axis of the photoconductor 1, and the arrangement direction is along the axis of the photoconductor 1. The thickness of the metal plate 15 between the ribs 14 is thinner than the height of the ribs 14. The metal plate 15 is grounded to a metal support member such as a chassis (not shown).

In such a structure, as described in the description of FIG. 3, the potential of the toner image on the photosensitive member 1 is negative, the potential given to the paper 7 from the transfer unit 4 is positive, and the metal plate 15 grounded. Is given a negative potential. As a result, the toner image on the photoconductor 1 is transferred to the paper 7 by the transfer device 4,
Since different potentials are applied to the metal plate 15 and the paper 7, the paper 7 can be sucked by the metal plate 15 and quickly separated from the photoconductor 1. Further, since the paper 7 supported by the ribs 14 does not come into contact with the metal plate 15, it is possible to avoid a state in which the potential applied to the paper 7 for transfer escapes to the other, whereby the transfer on the paper 7 is prevented. The formed toner image can be stabilized, and the stable state can be maintained and fixed.

In the above embodiment, the regular development is described as an example, but consider the case of reversal development. In this case, the photoreceptor 1 charged with a positive potential is partially exposed,
Since a negative electrostatic latent image is formed on the exposed portion, the toner charged to a positive potential is attracted to the electrostatic latent image. In this case, the electric potential given to the paper 7 from the transfer device 4 is negative. Therefore, by applying a positive potential to the metal plate 15, it is possible to achieve the same purpose as in the above embodiment.

[0012]

As described above, the present invention provides the shield case with a non-conductive paper guide having a plurality of ribs,
A metal plate made of a material thinner than the rib is placed between the ribs, and the metal plate is applied with an electric potential having a polarity different from that applied to the paper from the corona discharger. It is possible to prevent the occurrence of jam by sucking it with a plate and quickly peeling it from the photoconductor, and since the paper supported by the rib does not contact the metal plate, it was given to the paper for transfer. It is possible to avoid a state in which the electric potential escapes to the other, which makes it possible to stabilize the toner image transferred onto the sheet until the time of fixing and improve the image quality.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing a relationship between a shield case and a paper guide.

FIG. 3 is a vertical sectional side view showing a conventional example.

[Explanation of symbols]

 1 Photoconductor 7 Paper 9 Fixer 10 Opening 11 Shield Case 12 Corona Discharger 13 Paper Guide 14 Rib 15 Metal Plate

Claims (1)

[Claims] 1. A shield case in which an opening facing a photoconductor on which a toner image is formed is formed on one surface and a corona discharge body is provided inside, and from the inside of the opening of the shield case to the fixing device side. And a plurality of ribs protruding from one surface of the paper guide on the side of the photoconductor, and a non-conductive paper guide that is extended between the ribs and is disposed between the ribs. And a metal plate to which a potential having a polarity different from that of the potential applied to the paper from the corona discharger is applied.